FINAL REPORT - Stakeholders - Ofcom

Ofcom Contract AY4620 

Assessment of the technical, regulatory and socioeconomic 

constraints and feasibility of the 

implementation of more spectrally efficient 

radiocommunications techniques and technology within 

the aeronautical and maritime communities 

FINAL REPORT 

Aeronautical & Maritime Radiocommunications Services 

15 June 2004 

Web: http://www.icc-uk.com 

Email: info@icc-uk.com 

Web: http://www.connogue.com 

Email: info@connogue.com 

Web: http://www.helios-tech.co.uk 

Email: mike.shorthose@helios-tech.co.uk 

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Table of Contents 

1 Executive Summary.......................................................................................................... 8 

1.1 Overview 8 

1.2 Summary of recommendations 12 

1.2.1 Aeronautical Radiodetermination........................................................................12 

1.2.2 Maritime Radiodetermination ..............................................................................15 

1.2.3 Aeronautical Radiocommunications....................................................................15 

1.2.4 Maritime Radiocommunications..........................................................................17 

1.2.5 Licensing.............................................................................................................19 

1.2.6 General ...............................................................................................................19 

2 Introduction to Report.................................................................................................... 21 

2.1 Background 21 

2.2 Scope 23 

2.3 Purpose 23 

2.4 The International Organisations Involved 23 

2.4.1 The Aviation Community.....................................................................................23 

2.4.2 The Maritime Community....................................................................................27 

2.5 Spectrum Pricing Issues 28 

2.6 Disclaimer 29 

3 Aeronautical Radio Determination................................................................................ 30 

3.1 Introduction 30 

3.2 Ground Based Primary Radar 30 

3.2.1 Primary Radar Frequency Allocations ................................................................30 

3.2.2 Primary Radar Technology .................................................................................34 

3.2.3 Operational Requirements ..................................................................................40 

3.2.4 Regulatory and Standardisation Issues ..............................................................43 

3.2.5 Possible Improvements to Existing Technology .................................................45 

3.2.6 Replacement Technologies (In Band and Other)................................................51 

3.2.7 Allocation Sharing ...............................................................................................52 

3.2.8 Possible Overall Spectral Efficiency Improvements............................................55 

3.2.9 Socio Economic Issues.......................................................................................57 

3.2.10 Primary Radar Recommendations......................................................................60 

3.3 Secondary Radar (L-Band Secondary ATC) 62 

3.3.1 Introduction .........................................................................................................62 

3.3.2 Frequency Allocations (International & National)................................................62 

3.3.3 Technology Description ......................................................................................63 


3.3.5 Regulatory and Standardisation Issues ..............................................................68 

3.3.6 Possible Improvements to existing technology ...................................................71 

3.3.7 Possible New Technologies (in-band) ................................................................73 

3.3.8 Replacement Technologies (radio, other or none)..............................................76 

3.3.9 Allocation Sharing Opportunities.........................................................................82 

3.3.10 Possible Overall Spectrum Efficiency Improvements .........................................82 

3.3.11 Conclusions and recommendations....................................................................84 

3.4 Aeronautical Radio-Navigation Services (ARNS) 85 

3.4.1 Introduction .........................................................................................................85 

3.4.2 Frequency Allocations.........................................................................................86 

3.4.3 Technology Descriptions.....................................................................................89 


3.4.5 Regulatory and Standardisation Issues ............................................................103 

3.4.6 Possible Improvements to existing technology .................................................107 

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3.4.7 Possible New Technologies (in-band) ..............................................................109 

3.4.8 Replacement Technologies (radio, other or none)............................................110 

3.4.9 Allocation Sharing Opportunities.......................................................................111 

3.4.10 Summary Of Possible Overall Spectral Efficiency Improvements.....................113 

3.4.11 Conclusions and Recommendations ................................................................115 

3.4.12 Note on Mobile Navigation Aids – Radar Altimeters .........................................121 

3.4.13 Note on Mobile Navigation Aids – Airborne Radar ...........................................122 

4 Maritime Radiodetermination ...................................................................................... 124 


4.1.1 Background.......................................................................................................124 

4.1.2 Frequency Allocations.......................................................................................125 

4.2 Ground Based 126 

4.2.1 MSR (Maritime Surveillance Radar) .................................................................126 

4.2.2 RACONs ...........................................................................................................131 

4.2.3 SHF 14 GHz Ship Berthing ...............................................................................133 

4.3 Shipborne 135 

4.3.1 MSR (Maritime Surveillance Radar) .................................................................135 

4.3.2 SHF 9 GHz SARTs ...........................................................................................136 

4.3.3 Radar Target Enhancers (RTEs) ......................................................................138 

4.4 Conclusions and Recommendations 139 

5 Aeronautical Communications.................................................................................... 145 


5.2 Frequency Allocations (International & National) 146 

5.2.1 HF Communications (R) and (OR)....................................................................146 

5.2.2 VHF Communications(R) and (OR) ..................................................................146 

5.2.3 UHF Communications (NATO 230 – 380 MHz) ................................................147 

5.2.4 UHF Communications > 862 MHz – Public Correspondence ...........................147 

5.2.5 1.5/1.6 GHz – Satellite ......................................................................................147 

5.3 Current technology description 148 

5.3.1 DSB/AM (analogue) voice.................................................................................148 

5.3.2 HF voice............................................................................................................148 

5.3.3 Current data link technology .............................................................................149 


5.3.5 UHF Communications > 862 MHz – Public Correspondence ...........................152 

5.4 Operational requirements 152 

5.4.1 Overview of operational requirements ..............................................................152 

5.4.2 Role of HF and HFDL in supporting the operational requirements ...................152 

5.4.3 Role of VHF analogue communications in supporting the operational 

requirements....................................................................................................................153 

5.4.4 Relationship between airspace capacity and VHF spectrum requirements......153 

5.4.5 AMSS................................................................................................................154 

5.5 Regulatory and Standardisation Issues 154 

5.5.1 HF Communications (R) and (OR)....................................................................154 

5.5.2 VHF Communications Analogue and Digital (R) and (OR) ...............................154 

5.5.3 Extension of VHF band .....................................................................................154 

5.6 Possible Improvements to existing technology 155 

5.6.1 VHF voice: 8.33 kHz channelisation .................................................................155 

5.6.2 Movement of HF voice services to HFDL .........................................................156 

5.6.3 Movement of HFDL to Satcom..........................................................................156 

5.6.4 VHF datalink: upgrade of ACARS to VDL Mode 2 and initial transfer of ATIS and 

controller pilot dialogue....................................................................................................156 

5.6.5 VHF voice: reducing long term spectrum requirements for voice .....................159 


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5.7 Possible New Technologies (in-band) 160 

5.7.1 Emerging technologies .....................................................................................160 

5.7.2 VHF Communications Digital Links...................................................................161 

5.7.3 Possible use of Mode S SSR as a data link......................................................165 

5.8 Replacement Technologies (radio, other or none) 166 

5.8.1 Introduction .......................................................................................................166 

5.8.2 Establishment of new satellite services ............................................................166 

5.8.3 Broadband systems ..........................................................................................170 

5.9 Allocation Sharing Opportunities 171 

5.9.1 Gatelink.............................................................................................................171 

5.9.2 Transfer to commercial data links .....................................................................173 

5.9.3 Other sharing issues for further consideration ..................................................178 

5.10 Possible Overall Spectrum Efficiency Improvements 178 

5.11 Conclusions and Recommendations 180 

5.11.1 Introduction .......................................................................................................180 

5.11.2 Socio-economic issues (general)......................................................................180 

5.11.3 Short term measures ........................................................................................184 

5.11.4 Medium term measures ....................................................................................186 

5.11.5 Long term measures .........................................................................................189 

6 Maritime Communications........................................................................................... 191 


6.2 Short Range Devices 192 

6.2.1 Frequency and socio-economic considerations................................................192 

6.3 LF DGPS 194 

6.3.1 Frequency Allocations (international)................................................................194 

6.3.2 Technology Description ....................................................................................195 

6.3.3 Operational Requirements ................................................................................195 

6.3.4 Regulatory and Standardisation issues ............................................................196 

6.3.5 Possible Improvements to Existing Technology ...............................................197 



6.3.8 Allocation Sharing issues..................................................................................198 

6.3.9 Possible Overall Spectrum Efficiency Improvements .......................................198 

6.4 GMDSS in the United Kingdom 203 

6.4.1 UK Search and Rescue (SAR) at HF and MF...................................................205 

6.5 MF and HF Communications Services, Techniques and Technologies 205 

6.5.1 Automation and Adaptive Techniques ..............................................................205 

6.5.2 E-mail and Data Services .................................................................................207 

6.5.3 NVIS (Near Vertical Incidence Sky-wave) Propagation Techniques ................209 

6.6 MF - Communications 210 

6.6.1 Frequency Allocations (international, Region 1) ...............................................210 









6.6.10 Socio-Economic Issues.....................................................................................215 

6.7 HF Communications 217 




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6.7.9 Socio-Economic Issues.....................................................................................223 

6.8 VHF – Communications (International) 223 










6.8.10 Re-arranging the Frequency Spectrum of Appendix 18 to the Radio Regulations 

and Releasing Part of it for Other Applications................................................................228 

6.8.11 Socio-economic Issues .....................................................................................229 

6.9 VHF – Communications (Private) 230 

6.10 VHF - AIS (Automatic Identification System) 231 






6.10.6 Allocation Sharing Issues..................................................................................233 


6.11 EPIRBs (121.5 MHz / 243 MHz / 406.1 MHz) 234 





6.12 UHF – On Board Communications 235 

6.12.1 Frequency Allocations (international and national) ...........................................235 







6.12.8 Socio economic factors.....................................................................................236 

6.13 UHF Communications (GSM and IMT-2000) 237 

6.14 Maritime Satellite Communications in the 1.5/1.6 GHz Band and above 238 





6.14.5 Possible Improvements to Existing Technology, Possible New Technology (inband) 

239 

6.14.6 The ESV issue ..................................................................................................239 

6.15 Maritime Communications Spectral Efficiency 240 

6.16 The Global Maritime Distress and Safety System (GMDSS) and the International 

Convention for the Safety of Life at Sea (SOLAS Convention) 240 

6.17 Compliance of Maritime Equipment with EU Directives 241 

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6.17.1 Marine Equipment Directive..............................................................................241 

6.18 R&TTE Directive 242 

6.19 Conclusions 242 

7 Licensing ....................................................................................................................... 244 

7.1 General 244 

7.1.1 Structure of the Chapter....................................................................................246 

7.1.2 Acknowledgements...........................................................................................246 

7.2 Summary of European and National spectrum management regimes 246 

7.2.1 European Regulatory Framework .....................................................................246 

7.2.2 National Regulatory Regimes ...........................................................................249 

7.2.3 Public availability of information relating to fees and charges ..........................253 

7.2.4 Legislative basis of licensing, fees and charges in European Member States .258 

7.2.5 Change of Control Rules relating to radio spectrum licences ...........................261 

7.2.6 Relationship between Licensing, Fees and Charges........................................262 

7.2.7 Purpose of Administrative Fees and Spectrum Charges ..................................263 

7.2.8 Approaches to setting Administrative Fees.......................................................264 

7.2.9 Approaches to setting Spectrum Fees..............................................................265 

7.2.10 Approaches to setting Spectrum Charges ........................................................265 

7.2.11 ITU Notification .................................................................................................269 

7.3 Fees and Charges Information Provided 269 

7.3.1 Background.......................................................................................................269 

7.3.2 Fees and Charges Overview ............................................................................269 

7.4 Future Plans 288 

7.5 Identified Pricing Trends 288 

8 Summary of Report’s Conclusions and Recommendations .................................... 290 

8.1 Aeronautical Radiodetermination 290 

8.1.1 Primary radar ....................................................................................................290 

8.1.2 Secondary radar ...............................................................................................291 

8.1.3 Aeronautical Radio-Navigation Services...........................................................291 

8.2 Maritime Radiodetermination 291 

8.3 Aeronautical Radiocommunications 292 

8.4 Maritime Radiocommunications 292 

8.5 Licensing 293 

8.6 General Issues and Recommendation 294 

8.6.1 Standards and the European Regulatory Framework.......................................294 

8.6.2 The Market........................................................................................................295 

8.6.3 A Voluntary Approach .......................................................................................296 

8.6.4 Other AIP Issues...............................................................................................297 

ANNEX 1 Glossary of Terms................................................................................................. 298 

ANNEX 2 Mandatory Standards ........................................................................................... 307 

Annex 2-1 Aeronautical Radiodetermination Standards 307 

Annex 2-2 Maritime Radiodetermination Standards (SOLAS & Marine Equipment 

Directive) 317 

Annex 2-3 Aeronautical Communications Standards 318 

Annex 2-4 Maritime Communications Standards (SOLAS & Marine Equipment 

Directive) 321 

ANNEX 3 Harmonised Standards (R&TTE Directive) and Interface Requirements ......... 324 

Annex 3-1 Maritime Radiodetermination Standards 324 

Annex 3-2 Maritime Communications Equipment Standards outside the SOLAS 

Convention and the Marine Equipment Directive 325 

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ANNEX 4 List of pertinent ITU Recommendations for Maritime Services........................ 329 

ANNEX 5 Structure of the 4, 6 and 8 MHz HF Maritime Bands .......................................... 331 

ANNEX 6 Concerning AIS Carriage Requirements............................................................. 334 

ANNEX 7 References............................................................................................................. 336 

Annex 7-1 Aeronautical Radiodetermination References – Chapter 3 336 

Annex 7-2 Maritime Radiodetermination References – Chapter 4 338 

Annex 7-3 Aeronautical Communications References – Chapter 5 339 

Annex 7-4 Maritime Communications References – Chapter 6 344 

ANNEX 8 Countries in Receipt of Questionnaire................................................................ 345 

ANNEX 9 The Questionnaire................................................................................................. 346 

Prepared by: Approved by: 

Richard Womersley 

Mike Shorthose 

John McIntyre 

David Court 

Eberhard George 

Ben Stanley 

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1 Executive Summary 

1.1 Overview 

In these early years of the new millennium and as mobility becomes a progressively more 

valued commodity, it is clear that the radio spectrum is becoming increasingly important 

to society: an importance, which embraces both economic and social aspects. It is 

equally well recognised that the radio spectrum is a limited and finite resource and that 

the benefits which it affords society can only be realised, to their full potential, if the use of 

radio spectrum is carefully managed. 

The management techniques required, to ensure the effective use of the radio spectrum, 

are a function of the propagation characteristics of the part of the spectrum (band) under 

consideration, the demand for spectrum in that band and the use or uses to which it is 

being put. Thus, different management techniques need to be deployed in different 

bands to ensure that each can be used to its full potential. 

The demand for radio spectrum is ever increasing as more applications which require the 

use of spectrum are developed. This demand has been, to a large extent, successfully 

balanced by increasingly sophisticated spectrum management techniques, as well as 

improvements in the spectral efficiency of the technologies deployed. However, as radio 

spectrum is a finite resource, we are approaching the point where traditional spectrum 

management techniques, even taking into account developments in technology, are no 

longer able to guarantee access to the spectrum to those services which are requesting it 

and this in turn is leading, in some bands, to congestion and spectrum shortages. 

In the UK, it is the role of the Office of Communications (Ofcom) to manage the radio 

spectrum and with the above in mind, Ofcom has commissioned a study to assess the 

technical, regulatory and socio-economic constraints and feasibility of implementing more 

spectrally efficient radio communications techniques within the bands used by the 

aeronautical and maritime communities. These communities have, up until recently, been 

considered sacrosanct with respect to their spectrum use due, largely, to the international 

nature of the communities and thus the difficulties associated with taking significant 

measures at a national level, and the serious issues concerning the potential impact on 

safety of life. Professor Martin Cave in his 2002 ‘Review of Radio Spectrum Management’ 

in the United Kingdom reconsidered these aspects and indicated that a review of the 

situation for these users should be undertaken. 

Following an open competitive tender process, a contract (reference number AY4620) 

was awarded to a team consisting of InterConnect Communications Ltd, Connogue Ltd 

and Helios Technologies, to carry out the above study. This document is the final report 

prepared under the study and has been compiled as an input to Ofcom’s spectrum review 

process. Issues relating to Maritime and Aeronautical operations and safety are beyond 

the scope of this report as is their impact on spectrum requirements, for which normal 

consultation would take place. 

Professor Martin Cave in his review of radio spectrum management in the United 

Kingdom recommended that the Government should, wherever technically and 

operationally feasible, facilitate greater flexibility in the use of a given frequency band. 

This recommendation is generally pertinent since if by a combination of regulatory and 

technical processes it is possible to improve spectrum efficiency in any frequency band, 

congestion may be alleviated, more users accommodated or spectrum could be 

transferred to other users or alternative applications. However, there is not much flexibility 

for an administration to deviate from the rules agreed internationally. This has to be taken 

into account when considering possibilities to increase the efficiency of frequency usage. 

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It is against such socio-economic issues that the feasibility of introducing more spectrally 

efficient technologies must be considered. It will also be necessary to gauge the 

possibility and likelihood of whether significant changes to the status-quo are likely to 

occur within the various regional and international organisations. 

In both maritime and aeronautical industries, finding a way forward is limited by the 

difficulty of obtaining widespread fleet equipage for any particular solution. Furthermore, 

equipment costs tend to dominate any implementation strategy and spectrum 

considerations are given little consideration. The Consultant considers it important that 

Ofcom work to ensure that future solutions are spectrum efficient. Given the very long 

lead times for implementation, it is important now to ensure that correct implementation 

paths are chosen. 

Radiodetermination is a generic term for radionavigation and radiolocation and includes 

radar, navigational aids and systems such as ILS, VOR, radio altimeters etc. 

Concerning aeronautical radio determination, evolution in the following areas is 

highlighted: 

• Ground based primary radar, which provides non-co-operative surveillance of 

aircraft; 

• Secondary radar, which relies on cooperation from the target in the form of 

equipage with a suitable transponder; 

• Aeronautical Radio-Navigation Services. 

Concerning maritime radio determination, evolution in the following areas is highlighted: 

• Ground based systems; 

• Shipborne systems. 

Though opportunities for improving the spectral efficiency of the radar and associated 

technologies used for maritime radiodetermination are limited, there are potential 

modifications to spectrum use which could make overall more efficient use of spectrum. 

Improvements to existing technologies, replacement technologies, allocation sharing, 

spectral efficiency improvements and socio economic issues are discussed for both 

aeronautical and maritime areas, as listed above. 

Concerning aeronautical radiocommunications, evolution is driven by two key factors: 

• The saturation of the VHF radiocommunications band and 

• A steadily rising demand for ATS services and a potentially very large increase in 

demand for non-ATS services. 

Concerning maritime radiocommunications, the key issues are: 

• Maritime safety requirements are dominated by the internationally agreed 

GMDSS, SOLAS Convention and the Marine Equipment Directive, 

• MF and HF (especially public correspondence) requirements are declining in the 

developed world, 

• VHF public correspondence is also declining; however a number of important 

operational and safety functions are identified for the Appendix 18 (to the Radio 

Regulations) frequencies and on frequencies contiguous to Appendix 18, used in 

the UK for maritime business radio. 

• GSM is providing most maritime public correspondence traffic in the European 

maritime area. 

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Alternative uses might eventually be identified for redundant MF and HF spectrum, priority 

candidates would be improved maritime data services, digital broadcasting and defence 

applications. The Consultant is of the opinion that it may be beneficial to launch a 

European Spectrum Review covering the LF to HF bands to ascertain future requirements 

and develop a strategy which takes account of new technology, the development of 

regional markets and ensures the effective use of spectrum. The VHF bands might be 

rationalised taking advantage of redundant public correspondence channels and efficient 

spectrum saving techniques adopted to make maximum use of the remaining channels 

whilst providing backwards compatibility for the more important safety and operational 

functions. This would be subject to studies to determine actual requirements for public 

correspondence in order to ensure that premature release of spectrum does not 

compromise an important requirement. Spectrum released in all bands might be available 

for reallocation to other UK radiocommunication services, subject to any international 

constraints. 

The Consultant has identified an issue concerning GSM and IMT-2000 used to provide in 

many cases unplanned maritime public correspondence services as a result of service 

area overspill into surrounding maritime areas. Whilst 900 MHz systems appear to 

provide adequate coverage and has hastened the decline of planned public 

correspondence services, it is unlikely that IMT-2000 operating in the 2 GHz and 2.5 GHz 

bands will be suitable for maritime applications due to increased propagation losses. It 

appears necessary to determine the requirement for public correspondence in coastal 

waters in conjunction with a study to ascertain the actual use of spectrum in the 

international and UK CSR bands. 

The Report also addresses licensing and associated fees and charges. A particular 

requirement was to obtain licensing information from at least 30 prominent countries in 

order to provide a benchmark for future UK activities in this area. 

Questionnaires were sent to a number of key administrations around the World 

requesting detailed information on their approach to licensing and the application of 

appropriate fees and charges for radiocommunication systems used by the aeronautical 

and maritime communities. 

Unfortunately only a limited number of detailed responses were received in the time 

available, however this information was supplemented by publicly available material and 

updating material collected some 2 years earlier. 

In general Administrative Incentive Pricing (AIP) is not applied widely to aeronautical and 

maritime services. The only country where AIP seems to have been widely implemented 

is Australia. However even then Australia differentiates for aeronautical and maritime 

applications between those licensees who require an assignment and those that do not. 

Some countries e.g. the US and Canada where aircraft and small vessels that do not 

generally travel outside their national borders and are not subject to mandatory carriage 

requirements are exempted from licensing. In the case of Canada and the US there is 

also a bilateral agreement with respect to the free movement of ‘small’ vessels and 

aircraft between the two countries. A study could be conducted in the United Kingdom, 

possibly involving other British Isles administrations, addressing whether such an 

approach would benefit UK aviation and maritime industries. Such considerations might 

be restricted to the use of VHF aviation and maritime frequencies and on-board 

navigation apparatus. 

With respect to radiodetermination stations, mobile apparatus is often incorporated into 

the aircraft or ships licence at no extra charge. In the case of land radiodetermination 

stations the cost of licensing varies between zero as a result of minimal licensing 

requirements, for example if the systems are operated by governmental organisations, 

and a relatively high value such as found in Australia where the AIP regime has 

introduced bandwidth and operational frequency factors into the pricing equation. 

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There appear to be no clear patterns from the data collected; even an assumption that 

fees are generally intended to cover costs cannot be justified from the spread of values 

obtained. In principle, the Consultant is of the opinion that AIP should ideally be applied to 

all radiocommunication services in order to encourage the efficient and effective use of 

spectrum. However in view of the international aspects of these systems including safety 

and operational considerations as well as single market and European issues an 

innovative approach would be required to achieve such a development in Europe. 

In the case of the aeronautical and maritime sectors and maximising the spectrum 

resource available to them, the key issues would seem to be safety, market issues, the 

European regulatory framework, treaty obligations, standards, the introduction of new 

technology and last but not least the possible use of incentive pricing to realise spectrum 

efficiency gains within the sectors. 

A study of the issues involved has led the Consultant to suggest a voluntary process for 

consideration by the concerned parties, in this case Ofcom, the MCA, CAA and other 

stakeholders. The concept needs to be constructed in such a way that all parties feel they 

are gaining from the situation. A voluntary UK certification approach is suggested in 

parallel with the introduction of AIP to the aeronautical and maritime communities. The 

current UK interface requirement would be maintained but extended to include the 

voluntary category of equipment (for the R&TTE Directive) or a licence condition which 

met more strenuous spectral efficiency targets, thus attracting significant fees/charges 

discounts. Industry would have the benefit of developing a new generation of equipment 

with a subsequent increase in sales and likely mandatory carriage requirements in the 

future. Ofcom may gain spectrum but will need to promote the voluntary approach within 

Europe as a first step towards the formal revision of a standard and/or the issue of a 

Commission mandate to the standards bodies. 

Note that a number of general assumptions have been made in this report regarding the 

costs for new or upgraded equipment: 

• For aeronautical costs, the value of aircraft downtime in not considered since, in 

common with most other cost benefit assessments carried out in the community, 

it is assumed that new or upgraded equipment is provided during routine 

maintenance. However, it is acknowledged that in some cases additional 

downtime may be necessary although detailed consideration of this is beyond 

the scope of the current work. 

• Aeronautical costs for airborne equipment include the cost of the “service 

bulletin”, which provides all the procedures and documentation changes 

necessary to effect a certifiable equipment upgrade, but not “re-certification 

costs” which are negligible in comparison. 

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1.2 Summary of recommendations 

1.2.1 Aeronautical Radiodetermination 

1.2.1.1 Ground Based Primary Radar 

The recommendations arising from consideration of the primary radar technical, 

regulatory and socio-economic constraints have been grouped into the following 

categories: 

• Specific measures to release spectrum; 

• General improvements of spectral characteristics of primary radar; 

• Band sharing. 

The recommendations take into account the following key issues: 

• Spectrum planning must take account of the continuing operational requirement 

for primary radar for en route, approach/TMA and airport surface detection. No 

fundamental changes have been identified in the operational requirement which 

would reduce spectrum requirements. 

• Technology choice is driven primarily by the need to satisfy the operational 

requirement. 

• Spectrum planning will need to take into account some increase in potential 

demand for civil ATC primary radar services, particularly for approach/TMA 

facilities and surface movement radar. This is expected to grow in line with the 

general expansion in air transport and may be further influenced by security 

requirements. 

• There may be a requirement for reduced false alarm rates which needs to be 

taken into consideration in the determination of radar protection criteria and band 

sharing opportunities. 

It is not clear that there is any viable technology to replace primary radar – certainly not in 

the short term. In the absence of suitable alternative technologies, pricing would not 

provide any incentive to move away from primary radar. 

It should be noted that a number of the specific recommendations have already been 

implemented or planned by service providers. In particular, the use of solid state systems 

with pulse compression is becoming more widely adopted. 

Specific Measures to Release Spectrum 

Recommendation 3.1: Ofcom in association with the CAA may wish to consider whether 

it is feasible to replace the UHF Primary radars in Channel 36 in favour of S band or L 

band equipment. It is necessary to review the review the operational requirement for 

these systems and the appropriate timescale for replacement with the relevant operating 

authorities. It could be implemented as part of the normal equipment replacement cycle. 

Recommendation 3.2: The possibility of moving surface movement radars currently in 

Ku Band to X band should be considered thereby releasing Ku band for other 

applications. The cost of this is estimated at around £9m (project costs). The amount of 

spectrum released needs to be confirmed with the MoD. It could be implemented as part 

of the normal equipment replacement cycle. 

Recommendation 3.3: In the longer term, alternative systems with the potential to 

release spectrum should be further evaluated and developed. 

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General Improvements to the Spectral Characteristics of Primary Radar 

Recommendation 3.4: A long term policy to replace magnetron transmitters should be 

adopted. Such improvements could be instigated by CAA and Ofcom under the terms of 

the licensing agreement. The cost of replacing magnetron systems is estimated at £66m 

(S band and X band approach radars) and could be implemented under the normal 

replacement cycle. Increases in spectral efficiency are likely to be offset by increasing 

demand for radar services. 

Recommendation 3.5: In the short term, consideration should be given to equipping 

magnetron transmitters with low pass filters to meet the current emission mask. This 

approach may be necessary where the systems concerned have a long life expectancy. 

Costs are in the range £20k to £100k per installation. 

Recommendation 3.6: The current unwanted emission mask should be adopted as the 

medium term goal for primary radar systems. 

Recommendation 3.7: Pulse compression should be the technology of choice for future 

primary radar systems for both operational requirement and spectrum reasons. 

Recommendation 3.8: Solid state transmitters should be adopted for future systems 

given the ability to control pulse rise and fall times to minimise the out of band emissions 

and the single channel fail soft capability to minimise frequency requirements. This 

approach is also preferred for operational requirement reasons. 

Band Sharing 

Recommendation 3.9: More visibility of spectrum used by the military in the L and S 

bands may assist the delivery of improved spectrum efficiency. Ofcom should consider an 

initiative in this area. 

Recommendation 3.10: The overriding recommendation in the area of band sharing is 

for the development of a methodology which can assess the feasibility of band sharing. 

This would lead to a more strategic approach to the identification of band sharing 

opportunities. These developments should be carried out by a group representing all 

interested parties. 

Recommendation 3.11: Studies into the use of a statistical approach to band sharing 

opportunities should be continued and extended to include full consideration of 

operational and technical requirements of radar services. 

Recommendation 3.12: The use of 3D radars in ATC applications should be considered 

for long term R and D. Studies into the cost and benefits, operational validation and 

methods of funding should be reviewed. 

Recommendation 3.13: Increased standardisation of primary radar characteristics 

should be considered as a means for improving spectral efficiency and increasing 

compatibility with potential band sharing services. Improved spectrum utilisation 

characteristics should be a standardisation objective. Standardisation could be carried out 

by industry bodies such as EUROCAE for technical standards or by EUROCONTROL for 

operational standards. Global aspects would require the involvement of ICAO. It is 

considered that increased standardisation would achieve operational benefits as well as 

spectrum utilisation benefits. 

Recommendation 3.14: Band sharing should only be contemplated in a fully regulated 

environment. 

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1.2.1.2 Secondary radar 

The key developments which influence use of the 1030/1090 MHz frequencies are: 

• The transfer to Mode S from current SSR. As well as a number of operational 

benefits, this provides a reduction in the level of interference and makes it 

possible to maintain SSR services as traffic grows. 

• The implementation of ADS-B services via 1090 extended squitter, which whilst 

offering potential operational benefits, will increase the use of the 1090 MHz 

spectrum and possibly saturate. 

Recommendations 3.15 to 3.17 below apply to the efficient use by SSR of the 1030/1090 

MHz frequencies 

Recommendation 3.15: Ofcom should satisfy themselves that the CAA has taken the 

appropriate steps to ensure that the tailoring of SSR Pulse Repetition Frequencies 

conforms to ICAO recommendations. 

Recommendation 3.16: The implementation of Mode S SSR in the UK should be 

encouraged (allowing selective addressing and potentially fewer replies) coupled with the 

implementation of measures to encourage equipage and the appropriate implementation 

of controller tools which use the resulting data. 

Recommendation 3.17: Mode S Extended Squitter implementation – Ofcom should work 

with the CAA in ensuring that data downlinked from the aircraft is not superfluous to 

requirements. In particular this means reviewing the need for the regular broadcast of 

DAPs. 

The next two recommendations apply to the introduction of new services on the 1090 

MHz frequency. 

Recommendation 3.18: The 1090MHz channel will be severely constrained in the 

medium term. A review of the future use of this band should be carried out. The review 

should ensure that any new applications meet clearly defined operational requirements; if 

not, studies should be performed to assess the potential benefit against the cost to an 

already saturated channel. The studies should also assess the timescales over which the 

applications will remain effective given that increased traffic will further saturate the 

channel. Crucially, it should be ensured that the introduction of new applications does not 

impact on existing safety of life applications such as SSR and ACAS. 

Recommendation 3.19: Ofcom should work with the CAA to evaluate other technologies 

for ADS-B and ensure that spectrum efficient solutions are developed and implemented. 

The final recommendation applies to extension of the use of the 1030 MHz frequency. 

Recommendation 3.20: The possibility of further utilising 1030MHz (for example, for TIS- 

B) should be encouraged and studied. 

1.2.1.3 Aeronautical Radio-Navigation Services 

Recommendation 3.21: Ofcom should work with the CAA to ensure the timely 

decommissioning of non-operationally required radio navigation aids, in particular, NDBs 

and VORs. The following caveats apply: 

• The requirements of General Aviation and the Military for NDBs and VORs in the 

UK must be urgently addressed; 

• The impact of an RNAV only environment should be assessed, particularly from 

a safety and security viewpoint. 

Page 14

Recommendation 3.22: Ofcom should recommend to the CAA that a feasibility study be 

carried out into the potential for rationalising the DME spectrum to avoid the requirement 

for more spectrum elsewhere in the future. In practice, this would entail: 

• Looking at long-term allocations for DME, in light of the proposed DME/DME 

infrastructure, and the proposed implementation of the GNSS L5/E5 band (1164- 

1215MHz); 

• The feasibility and practical implications of the de-pairing of VOR, DME and ILS 

frequencies should be investigated, to allow better spectrum planning in the Lband; 

• The feasibility and practical implications of de-tripling of ILS/MLS/DME should be 

investigated, to free up spectrum for more efficient allocations; 

• Ofcom should work in conjunction with the CAA to ensure that studies are 

undertaken into the possible effects of UAT (ADS-B datalink) on DME 

frequencies. 

1.2.2 Maritime Radiodetermination 

Recommendation 4.1: The 5 GHz band is little used by (commercial) maritime radar in 

and around the UK. It is already shared with PMSE and HiperLAN. Further sharing of this 

spectrum with other suitably compatible services should be investigated. 

Recommendation 4.2: Consider a reduction in the allocations to maritime radar at 3, 5 

and 9 GHz. Such a reduction would require a study into congestion levels in the three 

bands. 

Recommendation 4.3: Introduce additional sharing, in particular with PMSE in the 3 and 

9 GHz maritime bands. 

Recommendation 4.4: A survey into the usage of ship-berthing radar should be 

conducted and a suitable allocation (if available and required) made available to enable 

them to be licensed. The potential for these (or indeed any other) unlicensed devices, to 

cause interference to legitimate spectrum users needs to be controlled and Ofcom should 

consider undertaking a market surveillance exercise to determine the size and nature of 

the problem. 

1.2.3 Aeronautical Radiocommunications 

1.2.3.1 Short term measures 

Recommendation 5.1: An urgent first measure is to promote the migration to 8.33 kHz 

spacing in the VHF band. This measure will alleviate the immediate shortage of VHF 

spectrum and facilitate the establishment of digital services. 

Implementation for high level sectors is limited by ground infrastructure limitations which 

NATS is addressing although no solution is currently apparent for air traffic sectors which 

cover a wide geographic area. For low level implementation, the barrier is GA equipage 

and an investigation of possible means to stimulate GA equipage should be carried out. 

Ofcom should work with the CAA to encourage the implementation of 8.33 kHz spacing 

including accelerating the necessary changes to the NATS infrastructure and considering 

the issue of, and a possible means of stimulating, GA equipage. 

Page 15

1.2.3.2 Medium term measures 

Medium term measures include: 

• encouraging the aeronautical community to bring demand for new voice 

channels under control through the introduction of more efficient air traffic control 

concepts such that the demand begins to level off; 

• transferring existing ACARS data to VDL Mode 2; 

• freeing up VHF spectrum by decommissioning VORs. 

The control of demand requires NATS to employ strategies to provide additional airspace 

capacity that rely on techniques other than systemisation. In the next 4 years, NATS will 

have implemented much of its Mode S programme. This in turn provides the data 

necessary to implement some initial controller tools with a resultant increase in capacity. 

In the longer term, concepts based on a greater delegation to the pilot offer the potential 

to provide much greater airspace capacity without the need to introduce more sectors. 

Planning for such a concept is needed now. However no specific recommendation for 

Ofcom is made on this issue since it is seen as primarily an issue for the aeronautical 

community only. 

Recommendation 5.2: The introduction of VDL2 provides an opportunity to transfer 

existing ACARS traffic with a resultant increase in spectrum efficiency by a factor of 10. 

ATIS services should also be transferred making possible the re-allocation of some of the 

spectrum. The introduction of VDL2 also provides an opportunity to introduce some 

controller-pilot dialogue services, which are unlikely to result in a decrease of voice 

channels but provide a means of preparing for a wholescale transfer in the longer term. 

Where parts of the VHF band are to be used for AOC and commercial services in 

general, Ofcom should consider administrative incentive pricing to encourage efficient 

usage. 

Recommendation 5.3: It is proposed that new VDL services will occupy the spectrum 

between 136 and 137 MHz (i.e. that spectrum newly assigned to aeronautical 

communications). However this spectrum is already in use for analogue services which 

will have to be found new frequencies below 136 MHz. One of the problems with the band 

136 to 137 MHz revolves around industrial, scientific and medical (ISM) heating 

machines. Such machines operate at frequencies around 13 and 27 MHz at very high 

powers for the purposes of drying (biscuits and paint commonly). Whilst these devices are 

not intended to radiate, the high powers involved mean that even small amounts of 

harmonic distortion can produce signals at higher frequencies that can cause interference 

to other services. Unfortunately the 10th harmonic of the 13 MHz band and the 5th 

harmonic of the 27 MHz band fall into the aeronautical communications band. This 

causes particular concerns for airborne receivers which have a very large radio line-ofsight. 

It was common practise, prior to the opening of 136 – 137 MHz for aeronautical 

communications, that these devices, if found to be radiating excessively on harmonic 

frequencies, were re-tuned such that the harmonics fell above 136 MHz and hence 

outside the aeronautical bands. This now means, however, that there are a large number 

of interfering carriers present on frequencies between 136 and 137 MHz. It will take 

further work by the relevant national administrations to clear these bands further so that 

they are suitable for the introduction of digital services (to which they cause greater 

problems than for analogue services). A first stage in the movement to data is to use 

136MHz+ for initial data services – Ofcom should work with the CAA to ensure that this 

part of the spectrum is used efficiently and that sources of interference are removed as 

soon as is practical. 

Recommendation 5.4: The decommissioning of VOR navaids will provide additional 

VHF spectrum for communications. It is important to take action to agree timescales 

Page 16

internationally for decommissioning and to assist NATS in varying the terms of its licence 

if required to remove barriers to decommissioning. Assistance may be required to GA 

users if the VOR network is decommissioned. Ofcom should work with the CAA to 

encourage the decommissioning of VOR navaids and re-use of the spectrum for 

communication purposes. (Note that this is also covered in recommendation 3.21) 

1.2.3.3 Long term measures 

Recommendation 5.5: It is important to determine a strategy for the long term transfer to 

data. This includes establishing plans for: 

• technology choice 

• clearing out of VHF spectrum 

Ofcom to work with CAA to ensure plans are put in place for a) the movement of voice to 

data and b) the gradual clearout and re-utilisation of the VHF spectrum 

Recommendation 5.6: Ofcom, working with the CAA, should ensure that solutions 

considered for future data link technology are beneficial when viewed in terms of 

spectrum utilisation and that no longer utilised spectrum is freed up where possible. There 

is consensus that aviation requires a new data link for future needs from 2012/2015+. The 

long term technology choice needs to consider: 

• the potential for low cost satellite based services, possibly shared with 

commercial uses 

• the potential for an optimised system utilising the VHF spectrum. 

The satellite route offers the possibility of sharing services with commercial users 

providing a possible route to lower cost. It seems preferable that aviation should avoid 

implementing a bespoke system. 

Use of a VHF system has the advantage of using spectrum dedicated solely to aviation 

use and providing a terrestrial system under the control of the aeronautical industry. The 

introduction of a new system will require a concerted effort to clear out existing use of the 

band. 

In all likelihood a dual strategy will be pursued with new systems operating both in the 

VHF and L bands. Ofcom needs to ensure that its own views on spectrum utilisation feed 

directly into the planning process in order that spectrum efficient solutions emerge. 

Recommendation 5.7: Ofcom should also investigate the possibility of applying in cooperation 

with the Ministry of Defence, the principles of recommendation 5.1 to the airground-air 

bands in the range 230 – 380 MHz, with a view to initiating a reduction in airground-air 

bands, ideally within NATO, Europe or as a minimum within the UK. 

1.2.4 Maritime Radiocommunications 

Recommendation 6.1: If a frequency solution for Short Range Devices (SRDs) 

based on globally available ISM bands does not meet all maritime requirements, the next 

best alternative would be to harmonise solutions capable of being implemented on a 

regional basis. In this regard it may be appropriate to specifically identify SRD bands 

appropriate for maritime applications in CEPT Recommendation T/R 70-03. It is 

recommended that such a course of action might be considered by the UK in WG FM of 

CEPT ECC (See Section 6.2). 

Recommendation 6.2: Section 6.3 and sections 6.5, 6.6 and 6.7 have indicated a 

possibility for new technology or change of use within the foreseeable future. However 

either option would benefit from a European market and harmonised frequency bands to 

ease co-ordination difficulties and provide economies of scale for industry. It is therefore 

Page 17

ecommended that the UK lobby for a CEPT DSI process for the band 30 kHz to 30 MHz 

within the CEPT ECC and the European Commission’s Radio Policy Committee, as well 

as introducing relevant technical, operational, economic and regulatory issues contained 

in this Report into the committee structure and decision making processes of the relevant 

international bodies. The overall objective should be to continue to promote innovation in 

the spectrum management process at the international level. (See Sections 6.3, 6.5, 6.6 

and 6.7). 

Recommendation 6.3: Very little use is made of the MF telegraphy band. Narrowband 

direct printing has not replaced Morse telegraphy as was expected to happen. 

Except on 490 and 518 kHz, and on 500 kHz which despite full implementation of the 

GMDSS has maintained a certain safety and distress function in some areas of the world, 

there is little traffic in the band 415-526.5 kHz. It is therefore recommended that an in 

depth and careful review of this band should be initiated with a view to allocate a 

significant part of it for other applications. This could be part a European overall spectrum 

review (DSI) covering LF, MF and HF spectrum, see Recommendation 6.2 (See also 

Section 6.6). 

Recommendation 6.4: Subject to the results of public consultation and any 

European DSI process (see Recommendation 6.2) it is recommended that new digital 

systems in the 2 MHz MF band should be considered on a national and non-interference 

basis taking account of the need to maintain interoperability with ships from foreign 

countries (See Sections 6.6). 

Recommendation 6.5: Adaptive systems have been successfully introduced in the 

fixed service in the HF bands. They would likewise offer great advantages to the maritime 

mobile service in the MF (see section 6.6.6) and HF bands. The implementation of 

adaptive systems on frequencies detailed in Appendix 17 to the Radio Regulations is 

permitted for initial testing through note p to the table in Part A of the Appendix. 

Frequencies from outside the maritime bands could of course be added to the group of 

frequencies used. It is understood that the final introduction of this new technology into 

the maritime mobile service requires further in-depth studies and the adoption of 

appropriate technical and regulatory provisions. It is therefore recommended, that 

regulatory pre-conditions are developed for the implementation of such adaptive 

techniques along the lines described above (See Section 6.7). 

Recommendation 6.6: In the HF bands, there is a rapidly growing need for digital 

technologies. Appendix 17 to the Radio Regulations, allows for initial testing and the 

possible future introduction within the maritime service of new digital technologies. The 

ITU-R is already conducting studies to improve the efficient use of these maritime bands. 

It is recommended that every effort is made to support these studies and refrain from 

implementing national solutions that might not be compatible with the outcome of these 

studies. With regard to SSB telephony, it is believed premature to advocate a changeover 

to digital techniques. In the longer term a transition to digital techniques, perhaps 

similar to those envisaged for digital HF broadcasting, may be considered (See Section 

6.7). 

Recommendation 6.7: It is recommended that an in depth study of all UK 

applications within the bands 156.0 – 158.5 MHz and 160.6 – 163.1 MHz ( including 

Appendix 18 (to the Radio Regulations) international maritime channels as well as Coast 

Station Radio private UK maritime channels) should be considered. The goal would be to 

determine: 

� The future VHF spectrum requirements of the UK maritime industry with a view to 

rationalisation of the current spectrum taking account recent changes in the 

industry and the introduction of new technologies. 

Page 18

� The study should further ascertain current and future maritime public 

correspondence needs and ascertain whether a combination of GSM/IMT-2000 

and satellite communications is likely to satisfy communications requirements in 

British waters. 

� Such a study would need to take account of the need to: 

o Ensure 25 kHz fitted ships would be able to operate as intended for an 

agreed period; 

o Ensure 161.975 and 162.025 MHz are maintained for AIS; 

o Seek to achieve a reduction in the number of two-frequency channels for 

port operations and ship movement. 

(See Sections 6.8, 6.9 and 6.10). 

Recommendation 6.8: Use of 12.5 kHz technology on all ten UHF on-board 

channels is recommended in order to minimise possible interference (See Section 6.12). 

Recommendation 6.9: The GSM system at 900 MHz is increasingly used by the 

maritime community as a substitute for maritime VHF public correspondence. IMT-2000 is 

now being implemented. In the long term, it will likely replace GSM 900. In order to 

maintain the obvious advantages of public mobile telecommunication systems for the 

maritime community, it will be of particular importance that IMT-2000 in coastal areas 

should be available in the 900 MHz band. This is because the 2 GHz band, whilst 

particularly suited for areas on land with high traffic densities and thus small cells, will 

have an off shore range that is inadequate for serving the maritime community effectively. 

It is therefore recommended that frequencies at 900 MHz should be made available for 

the implementation of IMT-2000 in coastal areas; when GSM is planned for 

decommission (See Section 6.13). 

1.2.5 Licensing 

Recommendation 7.1: 

In view of the trend to deregulate licensing in some countries in the GA sector and 

domestic maritime non-SOLAS sector, it is recommended that a study should be 

conducted in the United Kingdom, possibly involving other British Isles administrations, of 

whether such an approach would benefit the UK aviation and maritime industries. Such a 

development might be restricted to the use of VHF aviation and maritime frequencies and 

on-board navigation apparatus. The introduction of a class licence for such applications 

could also be linked to AIP i.e. the use of spectrally efficient wireless telegraphy 

apparatus would meet the terms of the class licence, whilst continued use of ‘old’ 

equipment would continue to attract fees. However the need to record MMSI details 

would have to be addressed. See also section 6.6.10. Although it is envisaged such a 

scheme could be limited to vessels registered by the flagging territories of the British Isles 

(two sovereign countries and three Crown dependencies), such a scheme might in future 

be proposed for extension to the European Union or CEPT. However the difficulties of 

attempting this are recognised. (see section 7.5) 

1.2.6 General 


Ofcom is invited to consider the establishment of a voluntary regime to develop a UK 

certification process to stimulate the development of spectrally efficient techniques which 

may lead to improved spectrum occupancy and efficiencies. Such a process would need 

the support of both user and manufacturing communities. In addition it could be promoted 

as a European process as a means to signify when a particular standard or standards 

Page 19

could be considered for revision. It is believed that such a process could benefit from the 

introduction of AIP to provide incentives to users to purchase new equipment. 

(see section 8.6.3) 

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2 Introduction to Report 

In these early years of the new millennium and as mobility becomes a progressively more 

valued commodity, it is clear that the radio spectrum is becoming increasingly important 

to society: an importance, which embraces both economic and social aspects. It is 

equally well recognised that the radio spectrum is a limited and finite resource and that 

the benefits which it affords society can only be realised, to their full potential, if the use of 

radio spectrum is carefully managed. 

The management techniques required, to ensure the effective use of the radio spectrum, 

are a function of the propagation characteristics of the part of the spectrum (band) under 

consideration, the demand for spectrum in that band and the use or uses to which it is 

being put. Thus, different management techniques need to be deployed in different 

bands to ensure that each can be used to its full potential. 

The demand for radio spectrum is ever increasing as more applications which require the 

use of spectrum are developed. This demand has been, to a large extent, successfully 

balanced by increasingly sophisticated spectrum management techniques, as well as 

improvements in the spectral efficiency of the technologies deployed. However, as radio 

spectrum is a finite resource, we are approaching the point where traditional spectrum 

management techniques, even taking into account developments in technology, are no 

longer able to guarantee access to the spectrum to those services which are requesting it 

and this in turn is leading, in some bands, to congestion and spectrum shortages. 

In the UK, it is the role of the Office of Communications (Ofcom) to manage the radio 

spectrum and with the above in mind, Ofcom has commissioned a study to assess the 

technical, regulatory and socio-economic constraints and feasibility of implementing more 

spectrally efficient radio communications techniques within the bands used by the 

aeronautical and maritime communities. These communities have, up until recently, been 

considered sacrosanct with respect to their spectrum use due, largely, to the international 

nature of the communities and thus the difficulties associated with taking significant 

measures at a national level, and the serious issues concerning the potential impact on 

safety of life. Professor Martin Cave in his 2002 ‘Review of Radio Spectrum Management’ 

in the United Kingdom reconsidered these aspects and indicated that a review of the 

situation for these users should be undertaken. 

Following an open competitive tender process, a contract (reference number AY4620) 

was awarded to a team consisting of InterConnect Communications Ltd, Connogue Ltd 

and Helios Technologies, to carry out the above study. This document is the final report 

prepared under the study. 

In support of the review of aeronautical and maritime radiodetermination and 

radiocommunications issues, a number of important countries were contacted during the 

study, with a view to collating information concerning their pricing regimes, which might 

act as a benchmark for future UK policy and strategy in this area. This report documents 

the authors’ views and recommendations on these matters. 

2.1 Background 

Ofcom has indicated that together with the CAA and MCA, a consideration of how 

administrative incentive pricing could be implemented for civil radar, including 

navigational aids needs to be addressed as well as determining suitable time scales for 

introduction. 

A starting assumption has been that fixed radionavigation stations may provide greater 

scope for more efficient spectrum use and possibly better frequency re-use than for 

mobile operation. The trade off between bandwidth and operational requirements is 

Page 21

addressed as well as any technological advances that may impact the balance between 

these two factors. 

Ofcom has indicated that where there is congestion and where UK based aeronautical or 

maritime users have alternatives concerning the technology choice for their on-board 

systems, then Ofcom, working with the CAA and MCA, should consider applying 

differential licence fees to encourage moves to more spectrally efficient equipment, thus 

easing congestion over time whilst taking account of the value of spectrum as an input 

cost. 

The pricing regime for Coast Station Radio UK (CSR (UK)) licences is based on 

frequencies which are not internationally harmonised and are permitted for use within 

territorial waters only. It is necessary to consider the possibilities of permitting the 

introduction of narrow-band technologies (e.g. 12.5 kHz/ 10 kHz/ 6.25 kHz/ 5 kHz) or 

even digital technology. Furthermore, issues will need to be addressed such as migration, 

parallel working, transitional arrangements and compatibility with existing systems. 

Consideration will also have to be given to those CSR licences that are based on 

internationally harmonised frequencies. Licensing and pricing issues are addressed in 

Chapter 7 of this Report. 

The study addresses the extent of possible interference on moored vessels to determine 

whether the additional 4 UHF maritime channels (making a total of 10) are likely to 

significantly increase spectrum re-use. If the results are favourable consideration could 

then be given to reviewing the pricing regime in this area to give an incentive for moving 

to 12.5 kHz channel spacing. 

The slow take up of using 8.33 kHz channels (instead of 25 kHz) for aeronautical VHF 

communications above FL 250 (approx. 25,000 ft) is investigated in order to ascertain the 

possible increased exploitation of the available spectral resource, especially given the 

high degree of congestion in this band. The practical implications and the consideration of 

technical issues such as Doppler shift and the present method of using frequency offsets 

need to be considered. 

The authors wish to record their appreciation for the assistance provided by NRA 

representatives in providing detailed information, the Civil Aviation Authority (CAA), the 

Maritime Coastguard Agency (MCA) and other key stakeholders (e.g. Port Authorities, 

National Air Traffic Services (NATS) etc.) to ensure that equipment carriage 

requirements, technical standards and Interface Requirements were taken into account. 

Completed questionnaires were gratefully received from Hong Kong, Turkey and the 

United Kingdom. In addition thanks go to those NRAs/administrations, who although not 

completing the questionnaire, provided detailed information in correspondence sent to the 

Consultant. 

The legacy regulator, the Radiocommunications Agency (RA) has completed the first part 

of a review of the pricing models that underpin the current Administrative Incentive Pricing 

(AIP) regime. This has determined an economically robust, logical and practical 

methodology for setting administrative prices for radio spectrum. The RA has begun to 

apply this set of guiding principles and theoretical perspective in order to make 

recommendations to set licence prices in broad use categories and to calculate their 

values in representative cases in each major area of radio application. This study is 

intended to provide the necessary input parameters to that review, providing information 

on the technical, regulatory and socio-economic constraints to implementing more 

spectrally efficient techniques and technologies in the maritime and aeronautical services, 

including the scope for use of different bands. 

In 2001 Connogue Limited participated in a study on administrative and frequency fees 

related to the licensing of networks involving the use of frequencies. This was focussed 

on the situation prevailing for public telecommunications networks within the European 

Union. This study builds on this work, extending considerations to aeronautical and 

Page 22

maritime radiodetermination and radiocommunication services in the European Union as 

well as in other prominent countries around the globe. The results of these studies will 

likely be used for benchmarking processes for a future UK licensing regime concerning 

such services. 

2.2 Scope 

This document has been compiled as an input to Ofcom's spectrum review process. 

Issues relating to Maritime and Aeronautical operations and safety are beyond the scope 

of this report as is their impact on spectrum requirements, for which, normal consultation 

would take place. 

The document addresses maritime and aeronautical radiodetermination systems as well 

as maritime and aeronautical radiocommunications systems. Technical, regulatory and 

socio-economic issues are considered in depth. Radiodetermination is a generic term for 

radionavigation and radiolocation and includes radar, navigational aids and systems such 

as ILS, VOR, radio altimeters etc. The document also addresses some defence usage of 

aeronautical radiocommunications since without dedicated spectral resources military 

aircraft would have to be included within civil systems for air traffic control purposes. 

Public telecommunications systems such as GSM and IMT-2000 are also considered. 

Although dedicated intra community (aeronautical/maritime) public correspondence 

services have failed commercially, the requirement for passenger telecommunications 

remains and to some extent is covered by land systems. 

The document also addresses the licensing situation in a number of prominent countries 

concerning maritime and aeronautical radiodetermination systems as well as maritime 

and aeronautical radiocommunications systems. This is likely to be used for 

benchmarking purposes. 

2.3 Purpose 

The purpose of this Report is to: 

1. Determine the technical, regulatory and socio-economic constraints and feasibility 

of introducing bandwidth efficient radars for both on-board and land-based 

maritime and aeronautical applications; 

2. Determine the technical, regulatory and socio-economic constraints and feasibility 

of introducing more spectrally efficient radiocommunications techniques and 

technologies within the aeronautical and maritime communities and 

3. Evaluate the aeronautical and maritime licensing structures and pricing details of 

30 relevant prominent administrations in order to provide an international licensing 

regime benchmark. 

The Report also takes account of any relevant EC, CAA, IMO, ICAO, IEC, ITU, ETSI, 

CENELEC, EUROCAE and/or EUROCONTROL technical and regulatory requirements 

and standards. 

2.4 The International Organisations Involved 

2.4.1 The Aviation Community 

This section describes the processes for the regulation of the radio equipment carried by 

civil aircraft. It identifies and highlights, in particular, the essential role of the agreements 

made in the International Telecommunication Union as they affect the radio systems 

carried by aircraft for air navigation. In this examination, it separates the two distinctive 

and complementary areas of regulation, the first for telecommunications, and the second 

Page 23

for aviation safety. Compliance with both is necessary before any international flight can 

be undertaken. It shows that the constituent parts of these regulatory processes have 

some functions arrived at through the process of international agreements, which are then 

incorporated into national regulations, and others (particularly the development of 

performance standards) which are developed by voluntary agreement between all 

interested parties and then adopted by national law as the basis of the regulation. 

Modern aircraft are equipped with many radio systems operating in a possible seventeen 

different frequency bands ranging from 9 kHz to 15 GHz. Approximately half of the 

systems have both transmit and receive functions, and the remainder are receive only. 

Three are for primary communications purposes, and up to twelve are for radio navigation 

functions, including three which have integral and complementary data links. In the 

course of a flight, an aircraft may traverse territory other than that of its State of registry 

and must therefore be regulated within a systematic framework of internationally agreed 

rules. These must ensure that the flight is safe for passengers and crew, and free from 

risk of damage to persons and property on the ground. As a part of this regulatory 

process, the radio installations must conform to agreed performance standards, must 

operate in correct frequency bands, must be licensed by appropriate authorities, and be 

operated by authorised personnel. 

The regulatory framework to ensure these requirements have, as their basis, two quite 

separate international agreements, which are implemented at the national level by two 

sets of national regulatory bodies. An outline description of the organisational elements of 

this framework is given below. 

Telecommunications regulation 

ITU World Radiocommunication Conferences agree the allocation of radio frequency 

bands to be used for aeronautical communications and radio navigation which are then 

incorporated in Chapter II, Frequencies, of the Radio Regulations. In this chapter, Article 

5, Frequency Allocations, contains the frequency allocation limits, the geographical scope 

and the status of the allocation, the sharing with other services, and any special 

conditions applying. Chapter VIII, Aeronautical Services of the Radio Regulations, deals 

with licensing, inspection, infringements, interference and related matters for aeronautical 

radio stations. The basic technical parameters for frequency stability, permitted levels of 

spurious emissions, and other spectrum use parameters, are agreed by ITU-R and 

embodied in ITU-R Recommendations which then may be incorporated by reference in 

the main body of the Regulations. Taken together, these form a body of regulations for 

use by national telecommunications authorities to control ground and airborne radio 

stations in regard to their basic transmit and receive functioning and their use. The use of 

radio in an aircraft when outside its state of registry must conform to these basic licensing 

conditions. 

Aviation regulation 

The safety aspects of the operation of civil aircraft are governed by the terms of the ICAO 

Convention on International Civil Aviation (Dot 7300). In the context of the carriage and 

operation of radio, Article 30 of the Convention states that “aircraft of each contracting 

State may, in or over the territory of other contracting States, carry radio transmitting 

apparatus only if a licence to install and operate such apparatus has been issued by the 

appropriate authorities of the State in which the aircraft is registered”. The Convention 

does not define the national body to exercise the function, which is normally that body 

with responsibility for telecommunications. Article 31 requires also that all of the radio 

equipment on board shall be covered by a certificate of airworthiness, invariably issued by 

the authority with responsibility for aviation safety. Article 37 calls for the adoption of 

International Standards and Recommended Practices (SARPs) dealing with, inter alia, 

communications and navigation aids. SARPs normally address all interface parameters, 

including radio frequency (RF), performance, coding, etc., to ensure worldwide 

Page 24

interoperability. These provisions form the major part of the international framework for 

aviation safety in regard to the radio systems carried by aircraft. It should be noted that 

ICAO SARPs are only agreed for systems which are standardized on a worldwide basis, 

and hence do not include such self-contained systems as radio altimeters, airborne 

weather radar, etc., carried as a mandatory requirement by many aircraft, and which also 

meet the proscribed certificate of airworthiness requirements. 

National regulations 

The respective national authorities, for telecommunications and for aviation in the State of 

registry of an aircraft, are responsible for ensuring compliance with the international 

agreements within their competence and jurisdiction. It is common for the 

telecommunications licence to be issued by that authority only when the aviation safety 

requirements have been approved and a Certificate of Airworthiness has been granted by 

the aviation authorities. The total authorization thus embodies the permission to transmit 

and receive radio signals (the telecommunications part), and the certification that the 

systems are satisfactory for the navigation of the aircraft (the air safety part). Aircraft are 

frequently transferred from one country to another, on delivery after manufacture, or by 

wet or dry lease during their life. The country of acceptance may agree to transfer the 

Certificate of Airworthiness with the aircraft as a practical means of compliance with 

international agreements. This latter procedure is recognized in Article 33 of the ICAO 

Convention and in Article 18 of the Radio Regulations. 

Regulations 

The process of airworthiness approval of the radio in aircraft includes requiring the 

assurance of the correct functioning of the equipment after its installation in the aircraft, 

which includes its performance as a working communications or radionavigation system, 

as well as its compatibility with other on-board radio and electronic systems. Prior to its 

installation, the equipment must have received approval under a Technical Standard 

Order (TSO) issued by a responsible body, such as the Federal Aviation Administration 

(FAA) in the United States, or the Joint Aviation Authorities (JAA) in Europe. 

A TSO defines the performance and environmental requirements for the airborne radio 

system concerned and is traditionally based on the Minimum Operational Performance 

Specifications (MOPS) developed in voluntary bodies, such as RTCA in the United States 

and the EUROCAE in Europe, This voluntary collaborative process, in which all of the 

interested parties (administrators, radio system manufacturers, aircraft constructors, 

airlines, etc.) participate, has the advantage of facilitating the achievement of 

performance parameters which are realistic and which can be manufactured at economic 

cost levels. 

Standardization of aircraft wiring and physical details (form and fit) is further carried out 

through the Aeronautical Radio, Inc. (ARINC) Characteristic, a document developed by 

the International Airlines Electronic and Engineering Committee (AEEC), for which ARINC 

provides the Secretarial service. The ARINC characteristic includes also all of the 

performance requirements, sometimes enhanced over that of the TSO, and is the 

generally used specification for the procurement of radio for commercial aircraft. 

The processes of airworthiness for most aviation radio recognize that some 

environmental and performance requirements can be relaxed for aircraft used only for 

private or pleasure purposes, outside the airspace used by commercial aviation and on 

short flights. The telecommunications requirements remain the same as those for 

commercial aircraft. 

Airworthiness requirements for radio not used for navigation or air traffic needs, e.g. 

passenger telephones, are usually limited to an assurance that it is not a safety hazard 

and does not, in any way, affect the correct functioning of the other radio and electronic 

systems carried for safety purposes. 

Page 25

The above describes the main regulatory features which apply to the use of radio in 

aircraft. They are characterized by: 

a) the requirement to observe two sets of international treaty obligations, ITU and ICAO; 

b) the participation of two national regulatory bodies, one for telecommunications aspects 

and one for air safety approval requirements; and 

c) a voluntary collaborative process for the preparation of performance specifications. 

In Europe, two other bodies are relevant to the setting of standards for aviation: 

• EUROCONTROL, which as well as taking a central role in the development of 

new technologies and air traffic management concepts produces equipment and 

application standards for use within the aviation community. 

• ETSI which through its technical committee, TG25, produces European Norms 

for ground equipment. 

The Single European Sky regulations, which have now been adopted, will provide the 

necessary legislative framework to drive Europe towards a more unified ATM system and 

provides the European Commission with the powers to stimulate the establishment of an 

ATM system roadmap and to ensure its effectiveness. 

The regulations cover ATM safety, the organisation and management of airspace, the 

integration of military requirements, the standardisation of systems and operations, the 

provision of air traffic services and on the human (air traffic controllers) aspects of Single 

Sky. 

The Single European Sky is a legislative framework, ultimately to support the sustainable 

growth in aviation by increasing ATM capacity, safety and efficiency. The regulations 

consist of: 

• Regulation of the European Parliament and of the Council laying down the 

framework for the creation of a Single European Sky, setting 

• a list of the high-level principles that must be followed in the creation of a Single 

Sky; 

• a definition of the work of the proposed Single Sky Committee; 

• a means of coordinating relations with non-Community countries; 

• supervision, monitoring, performance review and impact assessment 

mechanisms; 

• the provision of safeguards; and a 

• legislative financial statement. 

• Regulation on the provision of air navigation services in the Single European 

Sky, setting out a draft authorisation system, compliance review mechanism and 

revised payment arrangements for the provision of air navigation services within 

the Community. 

• Regulation on the organisation and use of airspace in the Single European Sky, 

setting out a mechanism to establish a single coherent Community airspace with 

common design, planning and management procedures. This includes the 

creation of a single new European Upper Flight Information Region (FIR) above 

28500 feet, to be followed within three years by the creation of a single FIR in the 

lower airspace. The Upper FIR would include a number of "functional" blocks of 

airspace designed to maximise system efficiency rather than as at present be 

restricted to national boundaries. 

Page 26

• Regulation on the interoperability of the European ATM network, setting out a 

draft regulation designed to achieve interoperability between the Community's air 

navigation service providers and the creation of an internal market in equipment, 

systems and associated services. This includes the establishment of European 

technical ATM standards in co-operation with EUROCAE and, where relevant, 

with EUROCONTROL. 

The regulations are compatible with, for example, ICAO, ECAC and EUROCONTROL 

standards. They build on these already established frameworks by providing the 

conditions for seamless integration of ATM in member States. Also, many aspects of the 

regulations give legal strength to already familiar concepts. Good examples are the 

Flexible Use of Airspace, or new standards such as the EUROCONTROL Safety 

Regulatory Requirements (ESARRs); which are very close to existing practices within 

some EU states. 

2.4.2 The Maritime Community 

When referring to regulatory, standardisation or other international considerations a 

number of international bodies are involved in the maritime scene. The key regulatory 

provisions are addressed in section 4sections 6.16, 6.17 and 46.18 below. This section is 

designed to provide the reader with a brief overview of the key bodies mentioned in the 

following paragraphs. 

At the regulatory level the key body in Europe is the European Union and a number of 

Directives, Decisions and other instruments are addressed in the following text, notably 

the Marine Equipment Directive and the Radio and Telecommunications Terminal 

Equipment Directive. 

Two United Nations specialised agencies play a major role in maritime activities. The 

Safety of Life at Sea (SOLAS) Convention of the International Maritime Organisation 

(IMO) obliges contracting states to ensure that relevant ships carry safety related 

equipment on board. The Global Maritime Distress and Safety System (GMDSS), an 

integral part of the SOLAS Convention, utilises radiocommunications to provide a 

homogeneous global emergency system for distress communications and the 

dissemination of safety information. Radio frequencies and associated technical matters 

are the responsibility of the International Telecommunication Union (ITU) via its 

Convention, Constitution and Radio Regulations as well as Recommendations and other 

instruments of its three specialist sectors i.e. Radiocommunications, Telecommunications 

Standardisation and Development. 

The regional regulatory telecommunication organisation for Europe is the European 

Conference of Postal and Telecommunications administrations (CEPT). This body works 

with the European Union in a co-operative manner with respect to electronic 

communications. Of particular relevance to this study is CEPT’s work on licensing, 

frequency management (including a common European frequency table), spectrum 

engineering and preparing the European position for ITU World Radio Conferences. 

CEPT also has an agreement with ETSI, the European Telecommunications Standards 

Institute concerning parameters within standards that may impact spectrum utilisation. 

ETSI together with CENELEC (European Committee for Electrotechnical Standardization) 

and CEN (European Committee for Standardization) make up the trio of European 

standardisation bodies, which can be mandated by the European Commission to produce 

harmonised standards which can provide a presumption of conformity with the essential 

requirements of ‘new approach’ Directives (e.g. inter alia the EMC and R&TTE 

Directives). These bodies also produce other voluntary technical standards. 

ETSI also co-operates with IEC (see below) and CENELEC concerning maritime and 

electromagnetic compatibility (EMC) issues respectively. In very simplistic terms ETSI can 

Page 27

e considered as the European version of the ITU telecommunications standardisation 

(and parts of the radiocommunications) sector whilst CENELEC has a close relationship 

with the IEC and its CISPR committee dealing with EMC. 

The International Association of Marine Aids to Navigation and Lighthouse Authorities 

(IALA) has established a number of committees which may produce recommendations. 

Of relevance to this study are: 

• Automatic Identification System (AIS): concentrating, on the introduction of AIS 

shore stations; 

• Aids to Navigation Management (ANM): concentrating on management issues 

experienced by members; 

• Radionavigation (RNAV): concentrating on both terrestrial and satellite systems 

such as GNSS and radar aids to navigation; 

• Vessel Traffic Services (VTS): concentrating on all issues surrounding VTS 

Technical committee No. 80 of the International Electrotechnical Commission (IEC) deals 

with maritime navigation and radiocommunication equipment and systems. It prepares 

standards for maritime navigation and radiocommunication equipment and systems 

making use of electrotechnical, electronic, electroacoustic, electro-optical and data 

processing techniques. 

The Radio Technical Commission for Maritime Services (RTCM) is an international nonprofit 

scientific, professional and educational organisation. RTCM members are 

organisations that are both non-government and government. Although started in 1947 as 

a U.S. government advisory committee, RTCM is now an independent organisation 

supported by its members from all over the world. Special Committees provide a forum in 

which government and non-government members work together to develop technical 

standards and consensus recommendations in regard to issues of particular concern. 

2.5 Spectrum Pricing Issues 

In addressing socio economic issues some consideration is necessary on Administrative 

Incentive Pricing. A number of ways of estimating the marginal value or opportunity cost 

of spectrum have been suggested including: 

• revenue of the organisations using the spectrum resource; 

• profitability of the spectrum using activity; 

• cost of the next best alternative (radio or non-radio) technology, alternative 

service or alternative frequency bands. 

However the first bullet indicates nothing about the value of the use of spectrum. For the 

purposes of this study the cost of the next best alternative has been used. 

Spectrum prices can be set through various selling mechanisms however the purpose of 

an administratively determined pricing system is to influence spectrum users so that: 

their applications for spectrum access would reflect the value they place on their 

spectrum use; 

applicants would consider alternative means of communication, not necessarily 

requiring access to the radio spectrum, and avoid use of the most congested 

frequencies; 

existing users would examine their spectrum needs and shed surplus spectrum; 

Page 28

new entrants and new technologies would have a greater chance of gaining access to 

the spectrum. 

It is then necessary to consider the alternative actions a user can adopt if denied access 

to a given frequency band. The possible actions vary across applications, but include: 

• using an alternative service (e.g. public communications rather than self provided 

communications); 

• using alternative un-congested frequency bands - these alternative frequencies 

must be in some way less attractive (in cost of exploitation and other terms) than 

the frequencies in question, otherwise they would already be used; 

• using an alternative technology (e.g. narrower bandwidth technology) which 

allows more efficient use of spectrum currently occupied by the user; 

• not using spectrum, and thereby either incurring higher costs or reducing profits. 

The additional "cost" of these alternatives, over and above the cost of using the spectrum 

in question, gives the spectrum its value. It is this additional cost that gives the marginal 

value of spectrum. 

Note that a number of general assumptions have been made in this report regarding the 

costs for new or upgraded equipment: 

• For aeronautical costs, the value of aircraft downtime in not considered since, in 

common with most other cost benefit assessments carried out in the community, 

it is assumed that new or upgraded equipment is provided during routine 

maintenance. However, it is acknowledged that in some cases additional 

downtime may be necessary although detailed consideration of this is beyond 

the scope of the current work. 

• Aeronautical costs for airborne equipment include the cost of the “service 

bulletin”, which provides all the procedures and documentation changes 

necessary to effect a certifiable equipment upgrade, but not “re-certification 

costs” which are negligible in comparison. 

2.6 Disclaimer 

Whilst every effort has been made to ensure the accuracy of the information contained in 

this report, the authors can not accept any responsibility for actions or decisions that may 

be taken as a result of the information herein. 

The opinions expressed in this Report are those of the authors and do not necessarily 

reflect the views of Ofcom, nor does Ofcom accept responsibility for the accuracy of the 

information contained herein. 

Page 29

3 Aeronautical Radio Determination 

3.1 Introduction 

In the aeronautical area, members of the study team have had meetings with UK CAA 

(DAP) and NATS. Informal responses have been received from the radar suppliers 

Thales and Raytheon. 

3.2 Ground Based Primary Radar 

Ground based primary radar is a long established tool for air traffic control services which 

has the basic virtue of providing non – co-operative surveillance of aircraft. The joint civil 

military nature of air traffic services in the UK is such that primary radar services are 

available to both parties for a range of operational requirements. Primary radar is 

expensive to provide and utilises substantial amounts of spectrum; however it continues 

to provide an essential service. 

3.2.1 Primary Radar Frequency Allocations 

3.2.1.1 Scope 

This section illustrates the current frequency usage profile in the UHF, L, S, X and Ku 

frequency bands for civil radar installations in the United Kingdom. 

3.2.1.2 UHF Band - 590-598 MHz 

The frequency band 590-598 MHz (TV channel 36) is allocated to DAP /MoD for 

aeronautical radio navigation. Two frequencies have been assigned by DAP for radars 

operating in this band. (Radars in this band occupy a necessary bandwidth (-20dB) of 1.8 

MHz). 

3.2.1.3 L-Band - 1215 MHz to 1365MHz 

The frequencies 1215 MHz to 1350MHz are used by DAP (Directorate of Airspace Policy) 

for primary radar subject to co-ordination with the MoD (in practice civil primary radar is 

limited to above 1243 MHz). The frequencies 1350 to 1365MHz may also be used by 

DAP subject to co-ordination with DTI. There are 34 ATC L-band assigned civil radar 

frequencies, 4 of which are reused (12%). Note that most radars require more than one 

frequency assignment, for example, due to multipulse working or frequency diversity 

operation. The band is also heavily used by the military (for radiolocation and GPS-L2), 

earth exploration satellites (space-to-earth) and the amateur radio service on a secondary 

basis. Civil radar frequencies and illustrative (20dB) bandwidths are listed in increasing 

order in Table 3-1 below. The highlighted entries indicate the reused frequencies. 

Page 30

Foperating MHz B-20dB MHz Foperating MHz B-20dB MHz 

1254.23 11/12.3 1305.00 3.9 

1255.00 16.7 1306.00 4.4 

1257.23 11 1312.00 Bandwidth not known 

1260.00 4.3 1317.23 11/12.3 

1260.23 4.3 1320.23 11 

1265.00 3.9 1321.00 16.7 

1266.00 4.4 1323.23 11 

1266.23 11 1325.00 4.3 

1269.77 6.8/6.3 1326.23 11 

1272.77 6.3 1332.77 6.3/6.3 

1275.77 6.3 1335.00 4.4 

1279.00 4.3 1335.77 6.3 

1281.77 6.3 1336.00 4.4 

1284.00 16.7 1338.77 6.3 

1285.00 4.4 1341.77 6.3 

1286.00 4.4 1345.00 4.3 

1288.00 Bandwidth not known 1349.00 16.7 

Table 3-1: L-Band ATC frequency assignments and -20dB Bandwidths 

Note: - In the case of multipulse radar services, the frequency allocations to the short and 

long pulses may be transposed but the overall bandwidth requirements are unaffected. 

3.2.1.4 S-Band - 2700MHz to 3100MHz 

The frequencies 2700MHz to 3100MHz are used by DAP/MoD for primary radar. This 

band is heavily used by the military and sharing with maritime users takes place above 

2900 MHz. There are 55 S-Band civil ATC radar frequency assignments in the U.K. 12 of 

these frequencies (22%) are reused. Civil radar frequencies and illustrative necessary 

bandwidths are listed in increasing order in Table 3-2.The reused frequencies are 

highlighted. 

Page 31


2710.00 7.0 2860.00 6.4 

2719.50 6.4 2865.00 4.0 

2720.00 6.4 2870.00 7.0 

2720.50 2.4 2881.00 6.4 

2721.00 9 2882.00 9.1 

2730.00 4.0/7.0 2885.00 10/7.0/7.0/10 

2735.00 7.0 2886.00 6.4 

2740.00 7.0/8.0 2890.00 7.0 

2744.50 4.4 2891.00 7.0 

2745.50 2.4 2895.00 6.4/6.4/10 

2749.00 1.6 2900.00 6.4 

2752.00 6.4 2908.00 10 

2760.00 10/10 2910.00 6.4 

2765.00 10/10/10 2915.00 6.4/6.4 

2770.00 1.6 2920.00 10 

2775.00 6.4/10 2933.00 6.4 

2784.50 4.4 2940.00 7.0 

2785.50 2.4 2950.00 10 

2800.00 10 2975.00 6.4/6.4 

2809.50 4.4 3000.00 6.4 

2810.50 2.4 3014.00 7.0 

2815.00 10 3016.00 7.0 

2833.00 10 3025.00 6.4 

2838.33 10 3030.00 6.4/6.4 

2840.00 6.4/5.7 3040.00 6.4 

2845.00 6.4 3050.00 6.4 

2850.00 6.4/5.7 3085.00 6.4 

2855.00 7.7 

Table 3-2: S-Band ATC frequency assignments and -20dB Bandwidths 

Note: - In the case of multipulse radar services, the frequency allocations to the short and 

long pulses may be transposed but the overall bandwidth requirements are unaffected. 

3.2.1.5 X-band - 9000MHz to 9200MHz and 9300MHz to 9500 MHz 

The frequencies 9000MHz to 9200MHz and 9300MHz to 9500 MHz are used by 

DAP/MoD for primary radar. There are 12 civil X-Band ATC radars operating in the U.K. 5 

of the 9 frequencies (56%) are reused. The frequencies and the approximate bandwidths 

are provided in Table 3-3. The reused frequencies are highlighted. 

Page 32


9170.00 73 9410.00 21/46/73/73/73 

9320.00 32/32 9460.00 32/32 

9345.00 25/46 9438.00 73 

9405.00 25/46 9450.00 55 

9425.00 73 

Table 3-3: X-Band ATC (PSR) frequency assignments in the UK 

Note that some radars in this band have selectable pulse width. Bandwidth is based on 

the shortest pulse width. 

3.2.1.6 Ku-band - 15.63GHz to 16.60GHz 

The frequencies 15.63GHz to 16.60MHz are used by DAP/MoD for primary radar. There 

are three frequencies assigned for ASDE equipment operating at three locations. All three 

frequencies are allocated to each of the three sites. As noted later, ASDE equipment has 

a very short range such that frequency reuse should be always possible. The bandwidth 

for all three systems is calculated at 73MHz. 

1 15650.00 

2 15800.00 

3 16400.00 

Table 3-4: Ku-Band ATC (PSR) frequency assignments in the U.K. 

3.2.1.7 Radar Sites and Ranges 

The relative location of the L-band radars currently in operation in the U.K. is illustrated in 

the Figure 3-1 below. The range for each station pair is recorded in Table 3-5. 

TIREE 

LOWTHER 

HILL 

CLEE HILL 

BURRINGTON 

HEATHROW 

PERWINNES 

HILL 

GREAT DUN 

FELL 

CLAXBY 

DEBDEN 

GATWICK 

PEASE 

POTTAGE 

Page 33

L Band 

Burrington 

Figure 3-1: L Band Radar Station Locations 

Claxby 

Clee Hill 

Debden 

Gatwick 

Great Dun Fell 

Heathrow 

Lowther Hill 

Pease Pottage 

Burrington 331 170 289 246 391 225 421 242 651 591 

Claxby 178 136 225 195 195 294 234 404 502 

Clee Hill 191 208 234 178 310 213 493 485 

Debden 98 327 85 426 111 545 625 

Gatwick 391 34 495 13 629 676 

Great Dun Fell 361 98 400 258 311 

Heathrow 451 38 604 640 

Lowther Hill 496 204 209 

Pease Pottage 634 681 

Perwinnes Hill 

Tiree 

272 

Table 3-5: Distances between L Band Radar Stations (Kilometres) 

3.2.2 Primary Radar Technology 

3.2.2.1 Primary Radar Background 

This section gives primary radar technology background relevant to frequency and 

bandwidth issues. 

Primary radar is currently in wide spread use in air traffic control world-wide. It operates 

independently of on board systems and is therefore the only system which detects non 

co-operating targets or weather data. Non co-operating targets can include aircraft with 

faulty transponders, light aircraft without any form of transponder or military aircraft that 

are seeking to avoid detection. Security considerations have recently enhanced this role. 

The basic principle of operation of primary radar is very easy to understand, however, the 

theory can be quite complex. 

The radar antenna illuminates the target with a microwave signal, which is then reflected 

and picked up by a receiving device. The radar signal is generated by a powerful 

transmitter and received by a highly sensitive receiver. The signal delivered by the 

receiving antenna is called echo or return. 

Lower microwave frequencies are less affected by weather conditions (particularly rain) 

than high frequencies. Returns from rain present a significant problem and are a factor 

in the choice of frequency for an ATC radar. However, low frequencies require much 

bigger antennas to achieve a narrow beam. 

A long range radar (with range up to 250 nm), may typically use frequencies in L band. 

This type of radar requires a very large antenna to resolve targets at long range. Note, 

however, that some long range radars operate on Channel 36 (UHF) and also in S band 

(no civil ATC en-route radars operate in this band). 

Typically, a short to medium range radar may use S band. This can be used to give a 

sharper beam for a moderate sized antenna, giving good performance to medium ranges 

(150 nm). An airport/terminal area radar, operating at shorter range (up to 80 nm), may 

have a smaller antenna with wider beam width. A very narrow beam is not so critical for 

shorter range applications. 

In contrast, an airport surface movement radar, operating at very short range, will use a 

higher frequency to achieve high resolution from a small antenna (a small antenna is 

necessary to achieve the required high rotation speed). The high resolution enables 

Page 34 

Perwinnes Hill 

Tiree

different types of objects (aircraft, buildings, vehicles etc.) to be distinguished. Most 

surface movement radars use X band or Ku Band. 

The time taken for the radar pulse to reach the target and return to the receiver provides a 

measurement of the slant range (distance) of the radar antenna from the target. The 

angular determination of the target is determined by the directivity of the antenna. The 

operating principle of pulse radar involves the transmission of a short pulse of microwave 

energy at regular time intervals. This transmission involves amplitude modulation of a 

micro-wave signal with the pulse signal. The duration of this pulse is known as the pulse 

width or pulse length. The receiver is listening between the successive transmitted 

pulses. Returns from an individual target arrive in a fixed interval (round trip time) after the 

transmitted pulse. 

The pulse width determines the range resolution capability of the radar. This is the ability 

of the system to distinguish between closely spaced targets on the same bearing. The 

range resolution is governed by the operational requirement; notably the required aircraft 

separation standard. The pulse width determines the necessary bandwidth of the radar, 

with higher resolutions requiring a bigger bandwidth. 

The time period is composed of one transmitted pulse and one listening period and 

repeats at a fixed rate; this is called the PRF (Pulse Repetition Frequency) and is 

typically of the order of 1 kHz ( long range radars have a low PRF and short range radars 

a much higher PRF). The ratio of the pulse width to the pulse repetition interval is called 

the duty cycle. Typical values for the pulse width and pulse repetition interval for 

aeronautical ground primary radar are 1 µ s and 1 ms respectively. It will be appreciated 

that depending on the PRF, antenna turning speed and beamwidth, several returns or 

“hits” will be received on each scan (one rotation) of the antenna. A large number of “hits” 

increases the signal to noise ratio. 

During transmission, the peak of the transmitted pulse defines the peak power. This is 

typically in the range 150 kilowatts to 10 megawatts for ATC radars. The mean power of 

the transmission is defined by the peak power multiplied by the duty cycle. The mean 

power is an important value since it is a measure of the total amount of microwave energy 

to be transmitted by the system. The EIRP of ATC primary radar systems is in the range 

75 to 95 dBW. 

Due to the Doppler effect, there is a frequency change in the received pulse relative to the 

transmitted pulse. This depends upon the radial speed of the target and can be used to 

discriminate moving objects from fixed ones. 

The Radar Cross Section (RCS) or target size is a representation of the magnitude of the 

echo received from the target. ATC radars are usually specified against a target size of 1 

to 3 sq metres. Radar coverage diagrams indicate the reference RCS for the coverage 

indicated. The RCS varies significantly depending on the type and size of target and the 

aspect of the illumination. 

In order to overcome target size fluctuations, many radars use two or more different 

illumination frequencies. This is known as frequency diversity and provides a significant 

gain in radar performance. Frequency diversity can be achieved in two main ways. In a 

dual channel system, both transmitters can transmit simultaneously on two different 

frequencies, thereby providing frequency diversity. Alternatively, a single transmitter with 

the required bandwidth can transmit pulses at two different frequencies in sequence. 

3.2.2.2 The Radar Equation 

Radar performance is governed by the radar equation which defines the maximum range 

of target detection relative to radar parameters. The basic form is: 

Page 35

R 

max 

⎡ 

= ⎢P 

⎢⎣ 

2 2 

G σλ 

⎤ 

3 

( 4 ) (min) ⎥ ⎥ 

p 

π Pr 

⎦ 

1/ 

4 

Where: Pp is the peak power 

Pr(min) is the Minimum Detectable Signal 

σ is the RCS 

and G is the antenna gain. 

It will be noted that range is proportional to the fourth root of transmitted power and that 

the longer the wavelength, the better the range performance. This is why 10cm radars 

are less used for long range radars. Coupled with improved immunity to weather returns, 

the lower frequencies are therefore attractive to system designers. The major 

disadvantage is the cost of an antenna with the required resolution. 

The minimum detectable signal is related to the probability of detection and probability of 

false alarm. A high level of detection with low false alarms requires a high signal to noise 

ratio. These closely interrelated aspects are also important in the context of band sharing 

and are covered in more detail in the band sharing section. 

3.2.2.3 Pulse Compression 

The radar equation indicates that if all factors have been optimised, the peak power must 

be increased by a factor of 16 to double the maximum radar range. Since the maximum 

level of the instantaneous power is limited (which is the case for modern solid state 

radars), an alternative (and usually easier approach) is to increase the pulse length. 

Unfortunately a long pulse degrades the radar resolution. The requirements for increased 

range and better range resolution clearly conflict for a conventional radar. 

Typically, in pulse compression radar, a long frequency modulated pulse is amplified by 

the transmitter output stage and passed to the antenna. The frequency increases linearly 

over the duration of the pulse. This is often described as a chirp pulse. On reception, the 

frequency modulated pulse is passed through a filter (the compressor) with a 

characteristic which delays the higher frequencies less than the lower frequencies. The 

net result is to compress the received pulse width and increase its effective peak power. 

Note that the process can introduce sidelobes in the time domain. These sidelobes are 

due to the non ideal characteristics of the compression filter and can generate false 

alarms. The principles are shown on Figure 3-2. 

Page 36

Frequency 

Amplitude 

Frequency 

Amplitude 

Time 

side 

lobes 

Time 

Time 

Time 

Time 

Expander 

freq.response 

TX output 

Compressor 

freq.response 

Compressed 

Pulse 

Figure 3-2: Basic Principles of Pulse Compression 

Many other encoding mechanisms can be used to obtain similar results. The degree of 

compression is characterised by the compression ratio, which is the ratio of the 

uncompressed pulse-width to the compressed pulse-width. Pulse compression provides 

the following benefits: 

• The use of long pulses with a high energy content to give longer range 

performance. 

• High resolution equal to the short pulse equivalent of the transmitted pulse (in 

proportion to the compression ratio). 

• Low peak powers can be used which are compatible with solid state transmitters. 

• Reduced overall bandwidth requirements (depending on the choice of operating 

parameters). 

• Reduced susceptibility to interfering signals, which use different encoding 

principles. However, it is more susceptible to interference, which uses similar 

encoding principles. 

Pulse compression increases system complexity and care needs to be taken to avoid the 

introduction of false alarms known as time side-lobes (see Figure 3-2). Also because of 

the length of the transmitted pulse, it is usually necessary to transmit an additional short 

pulse to ensure that the minimum range performance is achieved (this requires an 

additional frequency allocation but the transmitted energy is very low). However, on 

balance pulse compression is an excellent technique, which is used in the majority of new 

ATC primary radars. 

Page 37

3.2.2.4 Antenna Systems 

For most ATC applications, the antenna is required to produce a fan beam in the vertical 

cross section. This shape of beam ensures that optimum distribution of energy occurs 

with the upper limit of coverage set by the maximum altitude required and the lower limit 

set to minimise the energy transmitted into the ground. As the antenna rotates, it 

describes a coverage volume with the characteristics of a flat cylinder with the antenna at 

the centre. As already noted, the horizontal beamwidth is set to maximise angular 

resolution of targets. Typical beam widths are in the range 1 to 2 degrees which gives an 

indication of the directivity. Such beam widths equate to an antenna gain in the range 30 

to 35 dB 

This type of radar is only capable of defining target positions in two dimensions – range 

and bearing. Using modern phased arrays it is possible to “steer” the beam under 

computer control in two or three dimensions. Such techniques are very costly and have 

not been generally applied to ATC surveillance radars to date. 

Generally ATC radar antennas are horizontally polarised (i.e. with the electric field in the 

horizontal plane) which gives maximum response from aircraft targets. Circular 

polarisation is used as an option to improve the detection of targets in rain. 

3.2.2.5 Transmitters 

Radar transmitters are divided into two main types: driven and self-oscillating. This 

terminology refers to the nature of the output device. In a self-oscillating system, the 

output tube is simply switched on and off at intervals corresponding to the radar pulse 

width. The transmission frequency is determined by the tube itself. In a driven system the 

output device is a high power amplifier with the pulse pattern and transmission 

frequencies determined at low level by the drive circuits. Driven systems provide better 

control of the transmitted spectrum. 

The only self oscillating tube widely used in ATC radar is the magnetron. The magnetron 

is physically small and uses relatively lower voltages (typically 15 to 25kV). It is used 

where compact dimensions and low costs are at a premium. Typical applications include 

low cost airport radars and in aircraft where space is a problem. It is also widely used in 

marine radar applications. However, as a self oscillating device, it has poor spectral 

characteristics and stability. 

The klystron is widely used in ATC radars. It is used in high power applications and 

requires high voltages (typically 80 to 100kV). It therefore requires X ray shielding and 

numerous safety interlocks. 

The travelling wave tube can provide a wide bandwidth, which is necessary to transmit 

short pulses or permit frequency diversity operation. The cost of TWT’s is high, but this is 

usually offset by a long in-service life. 

Solid state devices operate with low voltages and have a long life expectancy. They are 

well suited to feeding conventional rotating antennas as well as planar array applications 

where they provide a distributed power source. They are also much better suited to pulse 

compression applications and generate pulses with good spectral characteristics. In 

applications where they are used to drive a conventional antenna, a power combining 

network must be provided. 

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3.2.2.6 Receivers 

The receiver system is responsible for the amplification of the weak signals received from 

the antenna. Virtually all radar receivers operate on the double superhetrodyne principle. 

Most of the gain and selectivity of the receiver is implemented in the intermediate 

frequency amplifier. The low frequency of the IF amplifier makes it easier to achieve good 

pass band characteristics. In primary radar, the IF pass band characteristics are not only 

matched to the bandwidth of the transmitted pulse, but the phase characteristics are also 

matched to achieve the optimum signal to noise ratio. Radar system bandwidth is also 

covered in section 3.2.5.13. 

Note that because the RF bandwidth is quite large, receiver front-end saturation and/or 

desensitisation plays an important part in determining the impact of interference. 

Also supported by theoretical and experimental findings is an extreme sensitivity of 

detection probability to changes in the radar receiver’s signal to noise ratio (S/N), in this 

case caused by adding interference signal power to inherent receiver noise. This is 

covered in more detail in the section on band sharing. 

3.2.2.7 Signal and Plot Processing 

The basic function of a signal processor/plot extractor is to maximise the detection of 

wanted targets in the presence of unwanted ground and weather returns. This is achieved 

by the analysis of the Doppler content of the received signals. Ground returns have little 

or no Doppler content and are rejected in favour of aircraft returns. Similar processes are 

applied to weather returns although fast moving weather may cause false alarm problems 

in the more basic type of signal processor. 

The output of the Doppler filter is normally put through a detection threshold process to 

control false alarms. The nature of this thresholding process and the ability of the system 

to discriminate against non- synchronous pulse interference is a very important factor 

when evaluating the feasibility of band sharing. This is covered in more detail in section 

3.2.7.3. 

The final stage is to determine target position from the hit pattern (plot extraction). This 

process involves correlating the hit patterns in range and azimuth to determine the target 

position. The type of Doppler filtering and the threshold process vary widely from one 

type of radar to another. 

3.2.2.8 Radar Data Processing and Display 

The processes outlined so far are generally carried out at the radar sensor. The target 

plots (often combined with secondary radar data) are then transmitted to the air traffic 

control centre or airport. The plots are then further processed into tracks (=correlated 

plots) for display to the operational controllers. Again the approach varies from one 

system to another. 

3.2.2.9 Technology Summary 

It can be seen that the primary radar chain from sensor to the controller’s display is 

designed to optimise the performance of a given type of radar. It is the bespoke nature of 

primary radar systems that makes generalisations of performance under differing 

conditions difficult to predict. 

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3.2.3 Operational Requirements 

3.2.3.1 Introduction 

The study has reviewed the future operational requirements for primary radar on the 

grounds that it is necessary to determine the service requirements as a prerequisite to 

consideration of spectrum requirements. This is particularly true given the long term 

nature of changes in ATC procedures and also the lead time involved in changes to 

spectral allocations. Furthermore, in the case of primary radar, a small change in 

operational requirements could result in a relatively large change in spectrum utilisation. 

3.2.3.2 Users 

The study is principally concerned with the civil ATC use of primary radar for the control of 

aircraft. This can include commercial aircraft, military aircraft and general aviation. The 

study has not included military defence aspects but the military ATC services are a joint 

operation with UK NATS and these joint civil/military requirements are included. Primary 

radar provides services to these customers in most of the bands considered. Exceptions 

include civil airport surface movement radars, which generally are not involved in 

providing services to military aircraft. 

NATS Approach/TMA Radar and En Route radar data is provided to additional users such 

as local airports. This ensures that maximum use is made of a given radar service. 

3.2.3.3 Approach/TMA Surveillance Radar 

Primary radar is used at airports and terminal areas to provide independent radar 

coverage. Larger airports use primary radar as a non co-operative aid which provides 

coverage in the event of SSR failure, non SSR transponder equipped aircraft and 

intruders. Smaller airports are often equipped with primary radar only as their main source 

of radar information. Primary radar for approach/TMA use is an accepted requirement 

throughout Europe and elsewhere. In the US, the FAA has announced a plan to renew 

primary radar in terminal areas with timescales extending to 2015. 

Generally such radars are characterised by a short range capability and a high data 

update rate (the result of a high antenna rotation rate). The high data update rate 

provides precision surveillance in the approach phase. These services are normally 

dedicated to a specific airport/TMA and are designed to provide good short range 

performance to runway thresholds. S band radars tend to be the preferred option for this 

application with 34 civil radars currently deployed. There are also 7 short range approach 

radars operating in the X band. 

Approach radars normally have ranges of less than 80nm with 60nm being a typical 

figure. Minimum range is typically 0.25 nm – this can be an important parameter because 

it dictates the maximum pulse width that can be used. 

Good low cover is of prime importance in the specification of an approach/TMA radar with 

the following requirement being typical: 

• Ground level from 0 to 2nm; 

• 300ft from 2nm to 15nm; 

• 2000 ft from 15nm to 40nm; 

• 5000ft from 40nm to 50nm. 

High level coverage is normally set at a ceiling of 30000 ft for all ranges. Turning speeds 

of 15 RPM are required if operating in a three nautical mile separation standard 

environment. 

Page 40

Target size (=Radar Cross Section) criteria are typically in the range 1 – 3 sq metres. 

Even at airports handling large commercial transport aircraft, the primary radar is normally 

required to detect and display intruding aircraft, which are of unspecified type. 

A typical specification includes the ability to detect small targets (1sqm) with a probability 

of detection of 90% and inevitably requires advanced processing to minimise the 

probability of false alarms (10 -6 ). S band is also widely used by the military. 

The general conclusion is that the basic operational requirement for civil approach/TMA 

radar is unlikely to change significantly in the foreseeable future. An exception may be 

that the requirement for a low false alarm rate may become more exacting. Also, the 

probability is that as aviation expands, there is likely to be increased demand for primary 

radar systems as more airports identify the need to have radar coverage to improve 

expedition and safety of traffic. 

3.2.3.4 Airport Surface Movement Radars 

There are a total of 8 airport surface movement radars operating in the UK (5 at X band 

and 3 at Ku band). Primary radar is the principle general purpose tool for monitoring 

aircraft, vehicles and potential obstructions on the airport surface. Other sensors, such as 

multilateration systems, are coming into use but they are likely to be complementary to 

the basic surface movement radar. Security considerations are likely to increase the 

demand for this type of radar. 

Surface movement radars are limited to a maximum range of about 2.5nm although 

operational requirements often specify the airport surface as the “range” requirement. 

Minimum range is of the order of 0.05nm. They operate with aircraft and vehicles in close 

proximity and are normally specified with a 60 RPM update rate. 

Ground movement radars are usually required to provide coverage to an altitude of 350 ft 

in order to display missed approaches, helicopter operations etc. Pulse widths are very 

short – for example 40ns – to meet the requirement for high resolution of detail on the 

airport surface. Given the requirement to monitor all aspects of the airport surface, 

surface movement radars general have only very limited signal processing. Data 

processing to provide correlation with other sensors and to track aircraft is becoming 

common. 

Monitoring of the airport surface is becoming increasingly important and some 

enhancement to the operational requirement is likely in the future. This is likely to take the 

form of more airports being equipped with surface movement radar and improved 

coverage at airports where surface movement radar is already deployed. 

3.2.3.5 En Route Services 

There are a total of 12 L band en- route radars in the United Kingdom and two of them 

are dual use (en route /airport). There are also two UHF radars. These radars support 

ATC services to traffic flying in airways (the specific route structure established mainly for 

commercial traffic and involving a mandatory ATC service) and off airways (traffic flying 

outside the airways which is a mix of all classes of traffic) for most of the United Kingdom. 

Secondary radar is the principle tool for the management of traffic flying airways although 

the civil controllers use primary radar to monitor traffic which may not be transponder 

equipped, traffic which has suffered transponder failure or other unidentified traffic. The 

Military ATC authorities use the en route primary radar services to provide services to off 

airways traffic. Mandatory carriage of SSR transponders is not required at low altitudes. 

NATS has a contract with the MoD to provide and maintain the MoD share of en-route 

primary radar services. 

En route radars are characterised by long range performance and relatively low data 

update rates. They are nearly always specified in conjunction with a secondary radar 

Page 41

system, which is usually co-mounted. They are normally integrated with a network of 

similar installations to provide national or international coverage. The data is usually 

provided to centralised air traffic control centres although in some cases the radar 

information is supplied to a local airport for Terminal and Approach use. En route radars 

are normally L band and provide good performance in adverse weather conditions. 

En-route radars normally provide range coverage in excess of 80nm and more typically 

160nm. Minimum range requirements are typically 1nm. Low coverage is usually more 

generalised, for example, 5000ft throughout the coverage volume. High level coverage 

requirements are typically 50000 ft. A rotation rate of 8 to 10 RPM is typical for a long 

range radar providing services to aircraft flying in the en route phase of flight where a 5nm 

separation standard is normal. 

En route primary radars are required to detect a wide range of aircraft types, some of 

which present a very small radar cross section. This means that a fairly stringent target 

size (=RCS) criteria has to be applied (1 – 2 sq metres). 

There has been significant debate regarding the need for en route primary radar for civil 

ATC but there is reluctance to dispense with the only non co-operative service in a safety 

of life environment. In addition, given the requirements of Military ATC, the basic 

operational requirement for en route primary radar is likely to continue for the foreseeable 

future. This view is supported by NATS current replacement plan for en route radar which 

includes primary radar facilities. Finally, the need for primary radar has undoubtedly been 

reinforced by the increased requirement to track non cooperative targets which may pose 

a security threat. This view was confirmed by both CAA and NATS. The requirement for 

primary radar is also covered in the section on Regulatory and Standardisation issues. 

The CAA noted the close relationship with the military in terms of frequency allocations for 

en route radar services. However, the CAA is not party to the overall military requirements 

for frequencies in the L and S bands. 

3.2.3.6 Coverage 

The general policy adopted by CAA and NATS is to provide coverage from two 

independent radar sources. This is required to satisfy the overall availability requirements 

noting that a given service can be interrupted as a result of equipment failure or planned 

maintenance. For example in the case of en route radar, normal practice is to provide 

overlapping cover at 5000 ft. Note that this results in an apparent over provision of 

services because several radars may provide coverage at higher levels. 

Coverage is usually referenced to a probability of detection. The quoted probabilities of 

detection are typically 90%. This figure appears low; however this is the level achieved at 

the edges of cover and is really a performance yardstick. Within the normal operational 

service areas much higher figures are expected. 

3.2.3.7 False Alarms 

Maintaining the required level of false alarms can be technically challenging and it is 

possible that the operational requirement for reduced false alarm performance will 

become even more exacting. This situation is one of the reasons why air traffic service 

providers are particularly sensitive to band sharing where an increased false alarm rate is 

a possible risk. 

3.2.3.8 Sector Blanking 

The use of sector blanking as a means of limiting radar interference is technically possible 

and is considered subject to the operational requirements for coverage. In practice, given 

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the normal requirement for 360 degree coverage and the wide range of users for a given 

radar service, it usually proves difficult to blank a specific sector. 

3.2.3.9 Primary Radar Operational Requirement Summary 

The position on the operational requirement for primary radar services can be 

summarised as follows: 

• In the UK, there is likely to be a continuing requirement for primary radar for en 

route, approach/TMA and airport surface movement applications. 

• The scope of operational requirements is likely to remain static although there 

may be a requirement for reduced false alarm rates. 

• The requirement for security based requirements is likely to increase. 

• The number of radar facilities supporting approach and surface movement 

requirements is likely to grow in line with the general expansion in air transport. 

• The requirement for long range primary radars is likely to remain constant with 

security issues a potential additional driver. 

Hence, there appears to be little scope for reduced spectrum requirements based on a 

relaxation of operational requirements. 

3.2.4 Regulatory and Standardisation Issues 

3.2.4.1 UK CAA 

The CAA (DAP) support the aviation line that dedicated spectrum for aviation is the 

correct approach but recognise that the case must be appropriately justified to ITU. 

The UK CAA Safety Regulation Group produces a number of policy, guidance and 

requirements documents which cover primary radar as follows: 

Air Traffic Services Operation Memorandum (ATSOM) No 39 (Issued to Service Providers 

in December 2000). The key statements from this document are: ‘PSR is the minimum 

level of equipment necessary to support any form of Radar Control, Radar Advisory or 

Radar Information Service. SSR may supplement the PSR to safely accommodate 

increases in traffic complexity or density. In the En-Route environment, PSR must be 

provided in areas of high density or high complexity. In areas of light traffic, but 

nevertheless requiring a surveillance service, standalone SSR may be sufficient. PSR is 

required wherever the Controlling Authority of the airspace concerned has a need to 

provide radar separation between transponding and non-transponding traffic.’ 

Air Traffic Information Services Notices (ATSIN) No 30. Issued to Service Providers in 

May 2003, reminds them of the continuing validity of ATSOM 39, and provides additional 

information concerning any changes to existing radar systems. ATSIN 35 extends the 

lifetime of ATSIN 30. 

Safety Requirements for the provision of Radar Services are contained in CAP670 Part C, 

Section 3, Surveillance. The material contained in this document sets out the 

requirements to be met by providers of civil air traffic services and associated services in 

the UK in order to ensure that those services are safe for use by aircraft and meet 

internationally agreed standards. Inherent in this process is the need to have control over 

the operating environment. In addition to requirements, the text offers explanatory notes 

and guidance material on acceptable methods of compliance with the requirements. This 

paper makes reference to spurious frequency components for primary radar and specifies 

a level of – 50 dB for spurious components relative to the mean power. 

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Operational procedures/requirements for the provision of radar separation are contained 

in the Manual of Air Traffic Services (MATS Part 1 (CAP493), Chapter 3 Section 10). 

The CAA has a departmental Policy Paper (10) that covers primary and secondary radar 

services including the relevant ATSINS and ATSOMS. It gives guidance to its Inspectors. 

This paper is in the process of being reviewed and brought up to date and it is planned to 

put it in the public domain. No major changes are anticipated as a result of the review. 

All the above papers (except Policy Paper 10) are currently in the public domain and can 

be downloaded from the CAA website (http://www.caa.co.uk ). 

3.2.4.2 ICAO 

The International Civil Aviation Organisation (ICAO) is the global organisation responsible 

for air navigation. It publishes International Standards and Recommended Practices 

(SARPS) for Aeronautical Telecommunication in Annex 10 to the Convention on 

International Civil Aviation. This document only makes limited reference to primary radar 

in the context of Precision Approach Radar (PAR). This includes standards for the PAR 

and the associated Surveillance Radar Element (SRE). These standards are defined 

because of the very specific accuracy requirements associated with precision approaches 

and do not define standards for conventional en route, approach/TMA and airport surface 

movement applications. 

3.2.4.3 European 

The EUROCONTROL ATM 2000+ strategy generally advises that primary radar shall be 

maintained in major terminal areas up to at least 2020. The EUROCONTROL Surveillance 

Standard reflects this requirement for primary radar in major terminal areas. 

EUROCONTROL also publish generic documents providing specifications for S band 

primary radars. Suitably tailored, these can be used by air traffic service providers for 

procurement purposes. As a consequence of the European Union Single European Sky 

initiative, the EUROCONTROL ATM2000+ strategy is placing emphasis on the need for 

improved security and improved civil /military co-ordination. These factors may result in a 

review of surveillance radar requirements including primary radar. On the general 

question of spectrum management, EUROCONTROL is currently developing a strategic 

action plan for improved aeronautical spectrum management across Europe. 

EUROCONTROL documents can be accessed on the website 

http://www.eurocontrol.int/index1.html. 

EUROCAE do not currently provide standards for primary radar but may provide a vehicle 

for standardisation work in the future (http://www.eurocae.org). 

It has been agreed within the ECAC (European Civil Aviation Conference) that a 

framework should be created in order to defend the civil aviation interests in respect of 

spectrum management. This integrated approach across Europe may complicate any UK 

initiatives in this area. 

3.2.4.4 General Points 

The supplier and service industries have adopted de facto standards for the operational 

performance of primary radar systems – typically the basic operational requirements for 

each class of radar outlined in section 3.2.3. However, the detailed algorithms for signal 

processing tend to be proprietary in nature. This factor makes it difficult to predict 

performance under interference conditions. 

On the question of the regulation of the aeronautical frequencies, the CAA, working with 

Ofcom and MoD, apply specialist expertise to spectrum management, frequency 

Page 44

management and planning. They also support Ofcom in terms of aeronautical 

requirements through bodies such as the ITU, ICAO and CEPT. 

The study excluded consideration of the military frequency requirements which may have 

significant impact on the primary radar utilisation status, notably in the L and S bands. 

The feasibility of increased standardisation of primary radar characteristics should be 

considered as a means for improving spectral efficiency and increased compatibility with 

potential band sharing services. This could be carried out by industry bodies such as 

EUROCAE for technical standards or by EUROCONTROL for operational standards. The 

UK CAA may also be willing to consider the incorporation of more detailed spectrum 

requirements in their documents such as CAP 670. 

Generally the detailed technical standardisation of primary radar is not highly developed. 

The self to self link nature of the system discourages technical standards which are 

difficult to apply. The consensus on detailed operational requirements for primary radar 

was outlined in section 3.2.3. 

3.2.5 Possible Improvements to Existing Technology 


Section 3.2.2 above (Primary Radar Technology) summarises the basic primary radar 

technology including some of the newer developments. 

This section is aimed at summarising the main techniques available to improve the 

spectrum utilisation of the current technology. The techniques described are essentially 

those that are considered proven for aeronautical safety of life applications. 

Primary radar transmits and receives its own signals. This has led to a situation where 

radar engineers have been able to design systems to meet specific operational 

requirements generally without regard to standards which are essential in a co-operative 

system such as Secondary Surveillance Radar. 

The consequences are that the characteristics of system vary widely and that each 

system must be considered on a case by case basis. Recommendations for 

improvements can only be guidelines as they may or may not apply to the specific 

systems concerned. 

Retrospective modifications to existing systems are generally very difficult to apply. This 

is because a radar system is usually a matched system where each component is 

optimised to meet the overall system performance objectives. An apparently small change 

in operating parameters often results in changes to other parts of the system and can be 

uneconomic. Improvements aimed at spectrum efficiency are generally more feasible for 

new systems provided the features are considered at the design stage. The life 

expectancy of primary radar systems is usually of the order of 15 to 20 years and this 

may govern the timescales for the introduction of more spectrally efficient systems. 

3.2.5.2 Efficient use of the radio spectrum by radar stations – Rec. ITU-R 

M.1372-1 

This Recommendation is a potential baseline for the consideration of spectral efficiency 

improvements. In summary, it addresses the questions of antenna performance (including 

3D systems), the use of advanced Doppler signal processing, integrators and constant 

false alarm detectors. The recommendation serves to illustrate the wide range of 

potential differences between radar systems with regard to spectral efficiency and 

suitability for band sharing. Most of the techniques are covered in the following sections. 

Page 45

3.2.5.3 Radar Frequency Spectrum Definitions 

The frequency spectrum can be considered in respect of three main definitions: 

• Necessary Bandwidth; 

• Out of Band Emission Region; 

• Spurious Emission Region. 

3.2.5.4 Necessary Bandwidth 

Recommendation ITU-R SM.1541 (Unwanted Emissions in the Out of Band Domain) 

defines the necessary bandwidth as “the width of the frequency band which is just 

sufficient to ensure the transmission of information at the rate and quality required under 

the specified conditions” 

The pulse width of the radar defines the necessary bandwidth of the transmitted signal. 

The necessary bandwidth is 20dB below the peak envelope value and is defined as the 

1. 

79 6. 

36 

smaller of B N = or , where t is the pulse duration and tr is the rise time. 

t. t t 

r 

Modified equations apply to pulse compression systems. 

Radar engineers also define the 3dB bandwidth which is the reciprocal of the pulse width. 

3.2.5.5 Out of band Emissions 

Recommendation ITU-R SM.1541 defines out of band (OoB) emissions as “emission on a 

frequency or frequencies immediately outside the necessary bandwidth which results 

from the modulation process, but excluding spurious emissions”. Out of band limits are 

based on the -40dB bandwidth of the spectrum of the transmitted waveform. 

where K is a constant which is typically about 6.2, although it varies depending on a 

number of radar parameters (see Recommendation ITU-R SM.1541). Modified equations 

apply to pulse compression systems. 

The extent of the out of band transmission is therefore governed by the pulse width and 

pulse rise time. Spectrum efficiency is maximised by using a pulse width which is exactly 

matched to the operational requirement for range resolution. In addition, increasing the 

pulse width and rise times reduces the level and extent of the out of band emissions. 

Tailoring the rise times is therefore one method of controlling the level of out of band 

transmissions. Limiting the out of band spectrum by the introduction of filters may 

introduce pulse distortion if the filtering is too severe. 

3.2.5.6 Spurious Emissions 

Recommendation ITU-R SM.1541 defines the spurious domain as the frequency range 

beyond the OoB domain in which spurious emissions generally predominate. In the case 

of pulse radars the boundary between the out of band and spurious domains is usually 

taken to be the point where the OoB limits have fallen to the spurious emission level 

specified in Appendix 3 to the Radio Regulations. The spurious emission levels that must 

be met by all new radio determination stations and existing ones from 1 st January 2012 

are detailed in Appendix 3 to the Radio Regulations. 

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3.2.5.7 Emission Masks 

The ITU and CEPT have developed emission masks for radars that are detailed in 

Recommendation ITU-R SM.1541 and ERC Recommendation (02)05 respectively. The 

current unwanted emission mask is shown in Fig 3-3 below. 

Figure 3-3: Current Out of Band Mask for Primary Radars 

3.2.5.8 Pulse Rise and Fall Time 

The pulse width and rise times have been noted as having a direct effect on the overall 

spectral requirements of the radar. Radar pulses are typically derived from transmitters 

where there is comparatively little control of the pulse shape. Furthermore, the most 

efficient way of transmitting energy is to generate a pulse with a rectangular shape. 

However, there are significant benefits to be obtained in terms of out of band and 

spurious emissions if the pulse rise times are controlled. In practice, the use of such 

techniques is likely to be essential if the recommendations of the emission masks are to 

be achieved. The use of solid state transmitters provides superior out of band spectrum 

control. This is because the rise times associated with solid state transmitters are typically 

in the range 100 to 200ns compared with 15 to 60 ns for a magnetron. Superior control of 

pulse rise and fall times resulting in reduced bandwidth requirements can be achieved by 

utilising modern solid state transmitters. 


The concept of pulse compression as applied to primary radar has been outlined earlier. 

For ground based ATC radars, this technology is now considered optimal and all the 

prime suppliers base their main product lines on this approach. The basic advantages 

are as follows: 

• Good range performance from long pulses; 

• High resolution equals compressed pulse equivalent; 

• Low peak powers – compatible with solid state transmitters; 

• No need for high voltages, waveguide pressurisation and dehydration; 

• Reduced overall bandwidth requirements (depending on the choice of operating 

parameters); 

• Reduced susceptibility to interference utilising different encoding principles. 

Page 47

The disadvantages can be summarised as follows: 

• Increased complexity due to pulse compression; 

• Requirement for separate pulse to meet minimum range requirements (separate 

frequency but low amplitude); 

• Potential for time sidelobes (=false alarms); 

• Cost. 

The first three disadvantages can generally be resolved by careful design. However, the 

cost of a pulse compressed radar weighs heavily on the smaller ATC service operators 

who often adopt low cost magnetron systems. Certainly they are likely to resist the early 

replacement of serviceable equipment which fully satisfies their operational needs. The 

introduction of incentives may bring forward replacement timescales. 

The bandwidth benefits of pulse compression (relative to a non-pulse compressed radar) 

depend directly on the radar parameters including the transmitter type. For example, an S 

band solid state pulse compression radar may have a 20dB (necessary) bandwidth of 

2MHz compared to a magnetron radar of 7MHz. There is, however, the need to provide 

spectrum for an additional pulse to provide adequate short range performance (bandwidth 

typically 4MHz). This pulse avoids the masking effect of the long pulse. Although the total 

spectrum benefits seem marginal, it must be remembered that the short pulse has 

significantly less energy. However, inappropriate choice of operating parameters could 

lead to increased bandwidth requirements. Note that it is the combination of pulse 

compression techniques and solid state technology (with slower rise times) that gives 

optimum spectrum utilisation. 

Pulse compression is the technology of choice because it provides good operational 

performance and superior control of bandwidth requirements. 

3.2.5.10 Self Oscillating Transmitters 

Self oscillating transmitters mainly use magnetrons as the output tube. Transmitters 

based on magnetrons are widely used in aeronautical approach radars (16 in S band and 

7 in X band). Only one civil L band magnetron system exists and this is to be replaced in 

the near future. They are also used in ASDE or Surface Movement Radars (SMR) 

operating in X band and Ku Band. A total of eight airports are equipped with SMR 

operating in these bands. They are cheap and produce the high levels of peak power 

required for radar applications. However they suffer form a number of undesirable 

characteristics from a spectrum utilisation point of view: 

• Pulse rise time is not controllable and inherently fast causing undesirable levels 

of out of band emissions; 

• They suffer from frequency drift; 

• They produce high levels of harmonics and spurious noise; 

• Frequency drift and a deterioration of spectrum occur with age. 

In addition the RF starting phase varies from pulse to pulse which limits the radar 

performance in the area of the Doppler measurements necessary to distinguish between 

fixed targets and aircraft. 

There is scope to improve the OoB and spurious transmission levels from a magnetron 

system by the use of low pass filters (see below). 

The recommendations concerning magnetrons are as follows: 

Page 48

• A long term policy to replace magnetron based transmitters (L and S band) with 

solid state transmitters should be adopted by service providers. Solid state 

technology is becoming available at X band. 

• In the short term, coaxial magnetrons with low pass filters should be adopted to 

meet the current unwanted emission mask. 

3.2.5.11 Driven Transmitters 

Driven transmitters provide a much higher degree of control of the transmitted waveforms. 

Until recently, klystrons and travelling wave tubes were the main output devices used in 

“driven” civil ATC radars. Klystrons are capable of high peak powers but with a 

restricted bandwidth which limits their use in pulse compression systems. They can suffer 

from a relatively high harmonic content in their output. Travelling wave tubes have a 

higher bandwidth capability but can only provide relatively low peak power outputs. They 

are ideally suited to pulse compression systems and are widely used by National Air 

Traffic Services in the current long range network (L Band) and as approach/TMA radars 

(S band). However, they suffer from relatively fast rise times thus limiting spectral 

efficiency. 

Most ATC radars employing valves require dual channels to achieve the specified level of 

system availability. Dual channel systems require two sets of operating frequencies. 

Solid state technology is now the preferred option for new L and S band systems although 

currently they represent only a small percentage of the installed systems in the UK. NATS 

has a long term radar replacement programme which will adopt solid state technology 

including pulse compression. 

Individual devices provide only low mean and peak powers. The low mean power 

limitation is overcome by using the appropriate number of devices in parallel while the low 

peak power limitation is overcome by utilising pulse compression. The output of individual 

devices can be combined in a combiner network and the output coupled to a conventional 

antenna in the normal way. Alternatively the individual devices can be placed on a 

radiating surface and the output combined in space. This is known as a phased array and 

represents a combination of transmitter and antenna technology. Solid state devices are 

ideally matched to the use of pulse compression to achieve overall spectrum benefits. 

Solid state technology can be designed to be inherently fail-soft. A fail soft capability 

means that a system element can fail without an interruption to the service. This is a 

consequence of using large numbers of modules in parallel and having some redundancy 

in the number of modules necessary to satisfy the operational requirement. This may 

obviate the requirement to have two channels of equipment for availability reasons. This 

approach may partially offset the higher initial cost of solid state equipment and provide 

savings in frequency allocations. 

Solid state technology (coupled with pulse compression) represents the optimum 

approach to the provision of ATC approach and long range radar services in terms of 

radar performance and controlled spectrum utilisation. Initial costs can be partially offset 

by single channel configurations and reduced operating costs. Significant progress has 

been made by service providers in the adoption of this technology. 

3.2.5.12 Antenna Design and Coverage 

Careful design of the antenna is necessary to avoid unnecessary illumination outside the 

areas of required coverage. This approach maximises the performance of the radar 

system and minimises the potential for interference to and from other systems. Generally 

radar systems utilise a narrow beam in the horizontal plane to provide adequate azimuth 

accuracy and resolution. In the vertical plane, a fan beam is used to provide adequate low 

level and high level coverage. These parameters are therefore directly linked to the 

Page 49

operational requirement. However, the narrower the beam the larger the sidelobe levels 

become. Sidelobes constitute unnecessary illumination and need to be minimised for 

radar performance reasons. Strong targets (=large aircraft) will be seen by the main beam 

as well as the sidelobes resulting in multiple detections of the same aircraft at different 

azimuths (if we are considering the azimuth sidelobes). Therefore, in terms of antenna 

design, the radar performance objectives coincide with the requirements of optimum 

spectrum utilisation. Modern primary radar antenna designs utilising either conventional 

antenna designs or phased arrays represent the state of the art in terms of two 

dimensional radar systems. 

Three dimensional radar systems using phased arrays, which have electronic beam 

steering under computer control in three dimensions, offer the possibility of confining the 

illumination to the specific areas occupied by the target (noting that a sweep of the full 

coverage volume is required to initially acquire targets). Such systems are technically but 

not operationally proven and would be very costly to implement across the radar 

infrastructure. In view of the benefits to radar performance and the spatial aspects of 

spectrum efficiency, the application of 3D (phased array) systems to ATC surveillance 

radar should be considered as a research topic. 

3.2.5.13 Filters and Bandwidth Requirements 

The subject of bandwidth requirements and filters is complex. The bandwidth of every 

radar is different depending on pulse width, pulse rise-time, pulse compression frequency 

deviation, type of output device, frequency diversity, multi-pulse working etc. Therefore, 

the bandwidth of every type of radar must be calculated individually for each of the 3dB 

bandwidth, the necessary bandwidth (-20dB) and the out of band limits (-40dB). 

In general the introduction of filters at any point in the transmit/receive chain with band 

pass characteristics less than the spectrum of the transmitted waveform introduces 

distortion to the pulses. This distortion can take the form of time sidelobes, which are 

additional pulses either side of the desired pulse. These time sidelobes can cause false 

alarms because they have similar characteristics to the basic pulse. 

Time sidelobes can be introduced by the filter required by pulse compression (see Figure 

3-2) or by filters which are designed to minimise the transmitted spectrum. 

Filters which minimise the transmitted spectrum are designed to reduce out of band and 

spurious transmissions. Such filters can be useful in reducing the OoB and spurious 

emissions of magnetron systems. Typically, a low pass filter could be used at the 40 dB 

bandwidth to provide compliance with the 20dB/decade roll off characteristic defined in 

Figure 3-3. Application of filters around the necessary bandwidth (20dB) is likely to result 

in the introduction of time sidelobes. In general, a band pass filter can be applied based 

on the 40dB bandwidth of the pulse without serious pulse distortion, time sidelobes or 

impact on radar range performance to meet the unwanted emission mask. 

3.2.5.14 Statistical Analysis 

The use of statistical techniques in relation to the evaluation of band sharing opportunities 

has been considered by ITU Radiocommunication Study Group document 8B/28-E – 

“Use of Statistical and Operational Aspects in the Radar’s Protection Criteria” 

This document outlines the use of a particular statistical approach to determine what 

constitutes an unacceptable degradation of the operational performance of a radar 

system in the presence of short term interference. The paper first makes some illustrative 

assumptions about the processing techniques included in the whole radar chain including 

the controller’s radar processing and display system. It then considers the effect of 

permanent interference on the probability of detection. This model is then extended to 

consider the effect of sporadic interference. The conclusion is that under the assumed 

Page 50

conditions, the effect of sporadic interference on probability of detection can be very 

small. 

The paper is a preliminary view only and recommends that the introduction of a statistical 

and operational aspects in the protection criteria should be further studied by WP 8B. This 

view is supported by the study team noting the following points:- 

• The assumptions used in the paper do not apply to all radar systems. In 

particular, the retention on the controller’s display of a “coasting” radar plot for up 

to four consecutive lost plots (an aircraft travels a long way in four rotations of 

the antenna) is not acceptable in many operational environments. For example, 

aircraft manoeuvring in the approach environment or military aircraft pulling high 

G turns. 

• The major issue is one of whether the safety case can be demonstrated in an 

interference environment. The ATC industry uses safety methodologies which 

are more related to those used in the nuclear industry in terms of safety 

requirements. 

• It is difficult to provide a generalised approach to statistical analysis in an 

environment where the radar characteristics and operational requirements vary 

significantly from one system to another. 

• The scope of the statistical study must be representative of current and future 

radar systems and their operational requirements. This will require an input from 

the specialists in the field. 

3.2.5.15 Improvements to Technology – Summary 

Improvements to the technology can be considered in three categories: 

1. Minor improvements to existing systems such as the incorporation of filters in 

magnetron systems which may provide limited benefits in specific circumstances. 

2. Improvements which are likely to be inherent in the design of new radar systems and 

provide more optimum spectrum utilization benefits. They include the adoption of 

design aim emission mask standards, controlled pulse shaping, pulse compression 

and solid state transmitters. 

3. More fundamental changes which are likely to give spectrum utilisation benefits. 

These include: 

• More studies of band sharing techniques involving, for example, statistical 

methods. 

• Advanced radar techniques, for example, bistatic or CW radar. 

• The use of electronically steered beam antenna technology. 

These techniques are characterised by the need for significant R&D and will take 

many years to implement. 

3.2.6 Replacement Technologies (In Band and Other) 

Primary radar is a unique technology in the sense that it requires no co–operation from 

the target under surveillance. There are no issues of fleet fit and as long as there is a 

requirement for an independent non co-operative facility of this nature then there are 

currently no alternative technologies. 

However, it should be noted that SSR is the main operational tool in controlled airspace 

and in many ways is the “replacement technology” for primary radar. The availability of 

SSR has minimised the demand for primary radar although not to the point where the 

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primary radar service can be withdrawn. Secondary radar is now the principal civil ATC 

surveillance tool with primary radar in a back up and safety net role. The use of low cost 

transponders is a constructive development to increase SSR transponder fit and hence 

the total population of transponder equipped aircraft. Subsequent sections describe the 

issues concerning SSR and the use of ADS in the long term. 

The parallel study “Techniques for improving radar spectrum utilization” is reviewing more 

radical alternative technologies for radar. These technologies are likely to require 

extensive trials in the context of design and operational proving before adoption by 

equipment suppliers and air traffic service providers. This view was expressed by both 

NATS and CAA. 

3.2.7 Allocation Sharing 

3.2.7.1 Current Situation 

Allocation sharing is already a fact of life. In L band, the allocated bandwidth is already 

shared with the military, amateurs (including wide band TV repeaters), earth exploration 

satellites, and GNSS. Meteorological wind profiling systems also are in this band although 

they are not an interference problem. L band is under consideration for sharing with 

Galileo and two military developments are under review. 

In S band, the allocated bandwidth is split between aeronautical radionavigation service 

(mainly 2.7 to 2.9 MHz) and the maritime radionavigation service (mainly 2.9 to 3.1 MHz). 

The military make extensive use of both the lower and upper parts of the band. Other 

sharing possibilities are aircraft telemetry, ENG/OB and UAV (Unmanned Airborne 

Vehicle) control signals. 

Also other interference sources such as wind farms are degrading radar performance 

particularly in terms of false alarms. The civil authorities do not have full control of the key 

bands. DAP co-ordinate with the military regarding frequency allocation but are generally 

not in a position to analyse the full impact of other services in the band. 

Allocation sharing in the aeronautical services is a relatively new requirement and the 

following sections are intended to highlight the technical feasibility and consider future 

approaches. 

3.2.7.2 Pulse Repetition Frequency Discrimination 

Most primary radar systems use a technique known as pulse repetition frequency 

discrimination to reduce the impact of adjacent radar interference. Essentially these 

systems are designed to reduce the impact of interference which is pulsed in nature and 

has an interpulse period which is not significantly shorter than the victim radar. This 

technique enables much better spectrum utilisation than would otherwise be the case. 

Note that it does not provide immunity to interference which raises the noise level for 

extended periods of time because of high duty cycle. 

3.2.7.3 Detection Thresholds 

It has been noted in the earlier section on Primary Radar Technology that radar 

performance (in terms of probability of target detection and probability of false alarms) is 

heavily dependent on the characteristics of the background noise. Typical primary radar 

systems use a detection threshold mechanism (constant false alarm rate detector – 

CFAR) in which the threshold is controlled by the average of received amplitudes in cells 

surrounding the test (target detection) cell, as a means of controlling the false-alarm rate. 

A typical method uses the outputs of several range cells, which are summed and 

multiplied by a constant to establish the detection threshold. The spacing of the cells is 

equal to the radar range resolution. This form of detection is susceptible to interfering 

Page 52

signals which populate the range cell samples. A simple example of this type of detector 

is shown in Figure 3-4. 

Input 

Figure 3-4: Constant False Alarm Rate Detector 

The detection threshold is designed to maintain a constant false alarm rate with respect to 

the back ground noise level, which has essentially homogeneous Rayleigh statistics. If 

the interfering signal does not have these characteristics, then the false alarm rate is 

likely to rise. Furthermore if the interfering signal fills the range cell samples then the 

threshold will rise, degrading the probability of detection. 

3.2.7.4 Interference to Noise Ratios 

In the specialist community, there are differences of opinion regarding the impact of band 

sharing proposals and the protection levels for primary radar are still under discussion. 

Primary radar system performance is very susceptible to changes in signal to noise ratio 

as is illustrated in Figure 3-5. 

Probability 

of 

detection 

.95 

.8 

.5 

.2 

M taps in each 

delay line 

Taped Tapped delay delay line line 

Sum 

Test cell cel 

Sum 

Non fluctuating 

Taped Tapped delay line line 

10-4 10-8 10-12 10-4 10-8 10-12 10-4 10-4 Sum 

10-8 10-8 Video (range under 

test) 

10-12 10-12 Comparator 

x K 

Probability of false alarm 

10 12 14 16 18 20 22 

Signal to noise ratio 

Output 

Detection 

Threshold 

Swerling 

1 

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Figure 3-5: Probability of detection as a function of signal to noise ratio 

Figure 3-5 is for illustrative purposes only and is not intended to support calculations. It 

shows two different types of target model: non-fluctuating and fluctuating (Swerling 1). It 

will be noted that the relationship between probability of detection and changes in signal 

to noise ratio is heavily dependent on the target model chosen. 

For a non-fluctuating target and a given false alarm rate, a one dB change in signal to 

noise ratio can reduce the probability of detection by about 28%. In the case of a 

fluctuating target, a one dB change in signal to noise ratio can reduce the probability of 

detection by some 8%. 

If the protection level is set at an interference level to noise ratio (INR) of –6dB, then the 

impact on overall signal to noise ratio is about 1dB. If the INR is set at –9dB, then the 

impact on overall signal to noise ratio is about 0.5 dB. 

In general, primary radar systems are very sensitive to interfering signals unless they 

have radar like characteristics i.e. a pulsed waveform with a low duty cycle. 


It has already been noted that the use of pulse compression improves immunity to 

interference provided that the encoding regime is significantly different. This underlines 

the potential benefits of planning band sharing to use differences in characteristics which 

optimise the immunity between services. For example it may be possible to adopt a long 

term policy to standardise ATM services on the use of pulse compression including 

guidelines on the encoding techniques. This may improve the probability of band sharing 

with other services which use different encoding techniques. 

3.2.7.6 Allocation Sharing Summary 

The points in the preceding paragraphs are intended to illustrate that extreme caution 

must be observed in the evaluation of band sharing with safety of life primary radar 

services. Band sharing may be a possibility but it is likely to require a number of 

changes to the installed radar systems, the application of standards to primary radar 

systems, the identification of the necessary characteristics of potential band sharing 

services and full analysis of their suitability. All this must be achieved with the support of 

the ATM equipment and service suppliers, candidate sharing system and service 

suppliers and regulators. It is proposed that this is developed as a band sharing strategy 

for the specific bands concerned. 

These points enable some observations to be drawn with regard to opportunities for band 

sharing: 

• Band sharing incurs the risk of increasing the false alarm rate and/or a reduction 

in probability of detection. 

• The CAA are acutely aware of the need for the efficient use of the spectrum 

including band sharing if the analysis can demonstrate no risks to the primary 

radar service. 

• There is a lack of primary radar standards which would assist the assessment of 

band sharing proposals. 

• The protection ratios (interference to noise ratio) need to be further developed. 

An agreed method for assessing the feasibility of band sharing should be developed as a 

first step. Such a methodology would then permit the development of an agreed strategy 

for band sharing. This strategy would take into consideration the characteristics of 

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potentially suitable band sharing services based on analysis by experts from both fields. 

This approach would also enable radar designs to incorporate protection mechanisms 

taking account of the long lead times involved. Band sharing with safety of life services 

can only be contemplated in a fully regulated environment. 

3.2.8 Possible Overall Spectral Efficiency Improvements 

3.2.8.1 The Concept of Spectral Efficiency 

It is apparent from preceding sections that primary radar systems satisfy a wide range of 

operational requirements and employ many different techniques to meet these 

requirements. Furthermore, the primary determinant of spectrum utilisation is the required 

radar resolution. The concept of spectral efficiency is therefore difficult to apply and 

produces little benefit over and above the simple relationship between the required 

resolution and bandwidth. 

These issues are covered in a paper “Considering the Concept of Spectrum Efficiency as 

applied to Radar” SE34(01)35. The paper considers the spectrum occupancy as inputs in 

terms of polarisation, time, space and frequency. The performance achieved such as 

probability of detection, update rate, volume of coverage and/or resolution can be 

considered as outputs. The key input parameter is bandwidth which is directly related to 

system resolution. The output side is much more difficult to define as all the parameters 

are interrelated. If system resolution were adopted as the only output parameter than 

virtually all radars would have similar efficiency. 

The operational requirement for radar resolution is directly linked to aircraft separation 

standards. The other critical factor is how the radar systems minimise out of band and 

spurious emissions which are governed to some extent by the technology used. These 

factors are covered in the earlier sections. However, the use of the term spectral 

efficiency in radar creates an impression that the degree of control of spectrum usage is 

more significant than it is for a given operational requirement. This view is echoed in the 

SE34(01)35 paper. 

The remainder of Section 3.2.8 therefore concentrates mainly on possible opportunities 

for withdrawing or relocating services from existing band allocations. 

3.2.8.2 CAA Frequency Assignment Process 

The CAA was asked to outline their frequency assignment process. This is an outline of 

their process in the context of S band: 

A new assignment requires the following parameters: 

1. Antenna gain characteristics; 

2. Antenna location and height above ground; 

3. Peak output power and feeder losses; 

4. Instantaneous transmitted bandwidth; 

5. Receiver IF bandwidth and sensitivity; 

6. LNA (Low Noise Amplifier) saturation level; 

7. PRF and pulse width; 

8. Any frequency separation requirements. 

The first step is to calculate the free space path loss between other civil radars in the 

same band within a radius of 70 nm. 

Page 55

The next step is to determine if signals from these radars will be close to or exceed the 

LNA saturation level. If any do, the assignment is not progressed further without 

agreement from both radar operators that they are willing to accept the situation. 

Assuming there are no problems with LNA saturation, the next check is to identify a 

candidate frequency. For this centre frequency, it is established whether signals from 

nearby radars will fall within the new radar’s IF band. If this is the case, the level of 

received pulses are calculated and checked that they are not more than 40 dB above the 

radar’s sensitivity. (This is considered to be an acceptable level for directly received 

pulses, which will not overload or distort the radar’s performance). If the received signals 

are above this level, then alternative frequencies are considered. In some cases, an 

alternative option is to consider whether the radar-to-radar antenna coupling can be 

reduced by applying some tilt to the new radar, thus benefiting from the antenna’s low 

elevation angle cut-off characteristics. 

The margin for directly received pulses (40 dB) assumes that both radars have similar 

PRF’s and pulse widths. If nearby radars have higher PRF’s or longer pulse widths, the 

margin must be reduced accordingly. 

When this process has been completed, and suitable frequencies (and frequency spacing 

if appropriate) have been located, the assignment is notified to MoD (Defence Spectrum 

Management) and MCA (if above 2.9 GHz) for co-ordination, where they apply their own 

compatibility process against their own radars. Assuming MoD and MCA confirm 

compatibility, the assignment is completed. 

3.2.8.3 UHF Primary Radar 

There are two radars operating in the United Kingdom. It may be opportune to consider 

whether it would be feasible to replace these systems in favour of S or L band equipment. 

This would move the radar systems out of the UHF band. It would be necessary to review 

the requirement for these systems and the replacement timescales with the relevant 

operating authorities. 

3.2.8.4 L Band and S Band Civil ATC Radars 

In these bands, we consider ATC radars provided by civil organisations such as NATS 

and airport operating companies. These bands are the cornerstone of ATC primary radar 

based operations in the UK. As the study does not include the examination of the military 

use of these bands, overall band utilisation cannot be accurately defined. 

However, by way of an example, it is instructive to look at the current utilisation of S band 

(see Table 3-2). S band (2.7GHz to 3.1GHz) is occupied by some 34 civil ATC radars. 

These radars are a mix of pulse compression systems (19) and single pulse systems 

(15). The number of frequency allocations varies according to main and standby 

requirements; or short and long pulse requirements in the case of pulse compression. 

The total occupied bandwidth (by civil radars alone) in terms of the minus 20 dB 

bandwidth is some 460 MHz in an occupied spectrum of 375 MHz. 

The limits on out of band transmissions are defined by the –40dB bandwidth which is 

much greater than the necessary bandwidth particularly for magnetron radars. When 

considering out of band transmissions there is a very high degree of overlap even when 

taking into account the re- use of frequencies due to path length and other geographical 

considerations. The fact that the services can operate on this basis is due to the PRF 

discrimination incorporated in the radars but it should be noted that this process has 

performance limitations. 

Given the disparate nature of the current and future systems, the consequences of 

improvements in spectral efficiency are also difficult to quantify. However, as outlined in 

section 3.2.5, there are a number of technology improvements which should be 

Page 56

ecommended for future good management of spectral efficiency. These performance 

improvements are unlikely to lead to any change in band allocation requirements in the 

short term although it can be expected that they will contain the future growth of civil radar 

system requirements within these bands. 

3.2.8.5 X Band and Ku Band Civil ATC Radars 

X band contains a mix of short range approach radars and surface movement radars. Ku 

band contains three surface movement radars (Heathrow, Edinburgh and Stansted 

Airports). The use of X band short range approach radars is likely to remain static for the 

foreseeable future. The use of surface movement radars is likely to increase as a result of 

increased traffic and security requirements. Given the short range requirements for 

surface movement radar and the downward looking nature of the antenna, the question 

arises as to whether two bands are necessary for this application. X band offers superior 

weather performance although a larger antenna is required to maintain beam shape 

requirements. The possibility of moving surface movement radars currently located in Ku 

band to X band should therefore be considered. 

3.2.9 Socio Economic Issues 

This section first considers general socio-economic issues associated with primary radar 

systems and then examines the cost and implementation issues associated with the 

potential spectrum management improvement initiatives outlined in the report. Any costs 

given can only be considered illustrative at this stage. 

3.2.9.1 Spectrum Management 

The UK CAA deploys a high level of expertise to manage aeronautical spectrum in coordination 

with the MoD. Coupled with close co-operation with Ofcom, this arrangement 

provides the appropriate level of expertise needed to achieve spectrum management 

objectives. Approaches to band sharing are discussed separately. 

3.2.9.2 Public Perception 

Primary radar is seen by aviation professionals and public alike as an essential safety of 

life technology. It is assumed that aircraft are under permanent surveillance by one 

system or another. The possibility that performance might suffer as a result of 

interference from a third party would probably be considered unacceptable. 

3.2.9.3 Equipment Costs 

The cost of providing aeronautical surveillance radar services is very high due to the high 

performance and integrity requirements. Also they are generally produced in low volume 

which results in substantial development cost overheads. 

Approximate project costs for a dual channel L band radar system are in the range £5m to 

£10m. Approximate costs of SSR equipment is in the range £2m to £4m. Building and 

services costs are very variable depending on location and access road requirements but 

are likely to exceed £4m. An S band Primary Radar is likely to cost around £3m 

including buildings. These high costs result in long life expectancy for the equipment 

which, in turn, reduces the rate of the modernisation of the technology. Replacement 

costs assume that the new equipment can be installed in parallel with existing equipment 

thereby avoiding service outages and related costs. These costs also make allowance for 

installation and formal acceptance procedures. 

It will be appreciated that air traffic service providers would be reluctant to spend these 

sums of money if cheaper alternative technologies were readily available. This is 

Page 57

particularly true of airports with lower traffic levels where the provision of radar facilities 

presents a significant budgetary requirement. 

3.2.9.4 Cost Recovery 

The MoD finances the majority of the L band costs in contract with NATS with NATS 

recovering the remainder through the mechanism of the en route charges. 

NATS recovers costs of airport radar services either directly through users or under the 

terms of contracts with airport operators. Non NATS airports recover costs directly from 

users. 

3.2.9.5 Replacement Planning 

NATS (NATS En Route Limited) has recently embarked on a major surveillance radar 

replacement project. This project envisages replacement of its entire UK radar network by 

2012. These are en-route facilities. Replacement of the approach radars, where NATS 

(NATS Services Ltd) provides airport air traffic services, is subject to the terms of the 

agreements with the airport operators. Although they mostly use TWT based “driven 

transmitters” with pulse compression, these facilities are likely to require replacement in 

the next five years or so. 

There are a large number of S band and X band approach radars based on magnetron 

systems in use at the “non NATS” airports. Any proposal to update these radars on 

spectrum management issues would require extensive consultation with the operators 

involved. Some of the X band systems at the smaller airports are very old. Their 

replacement with equivalent low cost systems may not be practical. 

3.2.9.6 Pricing 

The Cave report recommends incentive pricing to encourage the efficient use of the 

spectrum. This covers both differential pricing - to encourage alternative more spectrally 

efficient systems - and opportunity cost pricing - to encourage users to economise on 

spectrum based on the use of alternative technologies at the margin. It is not clear, 

however, that there is any viable technology to replace primary radar – certainly not in the 

short term. In the absence of suitable alternative technologies, pricing would not provide 

any incentive to move away from primary radar. On the other hand, pricing could be used 

as a mechanism to provide an incentive for the adoption of incremental changes (rather 

than outright replacement) to improve spectral efficiency or to explore band sharing 

possibilities. 

In the context of primary radar, most ATC providers are likely to adopt spectrally efficient 

technology during the next replacement cycle. 

The only incremental change proposed is related to the adoption of filters on current 

generation magnetron systems. Given that complete system replacement is likely to 

precede upgrade in most cases, the application of pricing for a limited application (filters) 

is not recommended. 

3.2.9.7 Specific Measures to Release Spectrum 

The proposal to withdraw radar services from the UHF Band may meet resistance from 

the operators of the two remaining radars. Although the radars are old, they are 

supported by adequate spares and an undertaking regarding the availability of 

frequencies until the equipment requires replacement. On the other hand the equipment 

is old. The cost and timescales of replacing the two systems needs to be examined 

alongside a review of the operational requirement. Based on this review, there are two 

Page 58

possible options which would reduce potential costs – use of alternative radar services 

and the use of an S band rather than an L band solution. 

The release of Ku band would involve the replacement of three surface movement radar 

installations at Heathrow, Stansted and Edinburgh. The traffic levels at all three airports 

are such that the facilities must provide comprehensive coverage. The costs are likely to 

be of the order of £9m (project costs). The amount of spectrum released needs to be 

confirmed with the MoD. A particular uncertainty in the cost estimate relates to complexity 

of providing adequate coverage. This needs expert assessment by NATS. 

The study on “Techniques for Improving Radar Spectrum Utilization” is likely to put 

forward proposals for new techniques which may be developed for use in air traffic 

services. These techniques are likely to require extensive development and evaluation 

over the long term. It is important that the resources and the timescales required to 

develop a mature product for deployment in air traffic control are not underestimated. 

3.2.9.8 General Improvements to the Spectral Characteristics of Primary 

Radar 

The report recommends the use of solid state transmitters and pulse compression as the 

technology of choice for replacement radar systems. This is likely to be implemented in 

the area of en route radars and approach radars at major airports during the next 

replacement cycle. Note that radar systems have a relatively long life expectancy – 

typically about 15 to 20 years so it may take some time before this generation of 

equipment is installed at all locations. A difficult area is the provision of this type of 

equipment at the smaller airports which currently use S band magnetron systems. Even 

more problematic are those airports which use limited range, low cost X band magnetron 

based equipment. These airports may find it difficult to justify the cost of solid state 

systems given the relatively low cost of magnetron systems. 

A long term policy of replacing magnetron systems is the appropriate objective and this 

could be encouraged by the adoption of the current emission mask as a national 

objective. The cost of replacing magnetron systems is estimated at around £66m (S band 

and X band approach radars) and could be implemented under the normal replacement 

cycle. Increases in spectral efficiency are likely to be offset by increasing demand for 

radar services. 

This approach has the disadvantage that the smaller airports may choose to dispense 

with a radar service rather than incur the cost of purchasing a new radar. Clearly this has 

safety implications. 

Some improvement in spectral efficiency could be achieved by the use of filters. This is a 

relatively low cost option with benefits only in specific circumstances. The cost is in the 

range £20k to £100k per installation. 

The use of modern spectrally efficient radars in L, S and X bands is unlikely to release 

spectrum for other purposes in the short or medium term although it can be expected that 

they will contain the future growth of radar system requirements within these bands. 

The requirements for improved spectral performance could be incorporated in the 

relevant CAA Policy papers. 

3.2.9.9 Band Sharing 

The overriding recommendation in the area of band sharing is for the development of a 

methodology which can assess the feasibility of band sharing. This would lead to a more 

strategic approach to the identification of band sharing opportunities. Air traffic service 

providers and regulators are required to adopt a safety oriented view which requires strict 

adherence to safety management procedures. Safety management procedures require 

Page 59

thorough hazard analysis which is often complex and time consuming. In engineering out 

risks, it is fundamental that they avoid losing control of the environment in which the 

safety related service operates. As a result, band sharing can only be contemplated 

where all band sharing parties operate in a fully regulated environment. Furthermore, they 

wish to understand and partake in the analysis of any potential risk situations. On the 

other hand the requirement for spectrum continues to grow and all parties have an 

obligation to demonstrate that spectrum is being used efficiently. 

In the technical domain primary radar does not share spectrum easily, however there are 

possibilities which should be examined. 

A further complication is the international aspect of both aviation and frequency 

assignment; however, it is considered that a UK initiative in this area would be productive. 

The need is therefore to provide a forum to discuss the band sharing issues in advance of 

the formal process. This would allow time for the analysis to be completed with the 

appropriate experts present, before the band sharing proposals are seen as a fait 

accompli. Forum members could, for example, participate in the proposed statistical study 

of band sharing with radar systems. 

The introduction of primary radar standards would assist the analysis of band sharing 

opportunities. These standards could be designed to take spectrum utilisation into 

account as a parameter. The need for such standards could be initiated by the CAA in 

conjunction with EUROCONTROL (operational requirements) and EUROCAE (technical 

requirements). Note, however, it is unlikely that these standards could be rigid in all 

respects given the self to self and proprietary nature of primary radar equipment. 

3.2.10 Primary Radar Recommendations 

The recommendations arising from consideration of the primary radar technical, 

regulatory and socio-economic constraints have been grouped into the following 

categories: 

• Specific measures to release spectrum; 

• General improvements of spectral characteristics of primary radar; 

• Band sharing. 

The recommendations take into account the following key issues: 

• Spectrum planning must take account of the continuing operational requirement 

for primary radar for en route, approach/TMA and airport surface detection. No 

fundamental changes have been identified in the operational requirement which 

would reduce spectrum requirements. 

• Technology choice is driven primarily by the need to satisfy the operational 

requirement. 

• Spectrum planning will need to take into account some increase in potential 

demand for civil ATC primary radar services, particularly for approach/TMA 

facilities and surface movement radar. This is expected to grow in line with the 

general expansion in air transport and may be further influenced by security 

requirements. 

• There may a requirement for reduced false alarm rates which needs to be taken 

into consideration in the determination of radar protection criteria and band 

sharing opportunities. 



provide any incentive to move away from primary radar. 

Page 60

It should be noted that a number of the specific recommendations have already been 

implemented or planned by service providers. In particular, the use of solid state systems 

with pulse compression is becoming more widely adopted. 

3.2.10.1 Specific Measures to Release Spectrum 

Recommendation 3.1: Ofcom in association with the CAA may wish to consider whether 

it is feasible to replace the UHF Primary radars in Channel 36 in favour of S band or L 

band equipment. It is necessary to review the review the operational requirement for 

these systems and the appropriate timescale for replacement with the relevant operating 

authorities. It could be implemented as part of the normal equipment replacement cycle. 

Recommendation 3.2: The possibility of moving surface movement radars currently in 

Ku Band to X band should be considered thereby releasing Ku band for other 

applications. The cost of this is estimated at around £9m (project costs). The amount of 

spectrum released needs to be confirmed with the MoD. It could be implemented as part 

of the normal equipment replacement cycle. 

Recommendation 3.3: In the longer term, alternative systems with the potential to 

release spectrum should be further evaluated and developed. 

3.2.10.2 General Improvements to the Spectral Characteristics of Primary 

Radar 

Recommendation 3.4: A long term policy to replace magnetron transmitters should be 

adopted. Such improvements could be instigated by CAA and Ofcom under the terms of 

the licensing agreement. The cost of replacing magnetron systems is estimated at £66m 

(S band and X band approach radars) and could be implemented under the normal 

replacement cycle. Increases in spectral efficiency are likely to be offset by increasing 

demand for radar services. 

Recommendation 3.5: In the short term, consideration should be given to equipping 

magnetron transmitters with low pass filters to meet the current emission mask. This 

approach may be necessary where the systems concerned have a long life expectancy. 

Costs are in the range £20k to £100k per installation. 

Recommendation 3.6: The current unwanted emission mask should be adopted as the 

medium term goal for primary radar systems. 

Recommendation 3.7: Pulse compression should be the technology of choice for future 

primary radar systems for both operational requirement and spectrum reasons. 

Recommendation 3.8: Solid state transmitters should be adopted for future systems 

given the ability to control pulse rise and fall times to minimise the out of band emissions 

and the single channel fail soft capability to minimise frequency requirements. This 

approach is also preferred for operational requirement reasons. 

3.2.10.3 Band Sharing 

Recommendation 3.9: More visibility of spectrum used by the military in the L and S 

bands may assist the delivery of improved spectrum efficiency. Ofcom should consider an 

initiative in this area. 

Recommendation 3.10: The overriding recommendation in the area of band sharing is 

for the development of a methodology which can assess the feasibility of band sharing. 

This would lead to a more strategic approach to the identification of band sharing 

opportunities. These developments should be carried out by a group representing all 

interested parties. 

Page 61

Recommendation 3.11: Studies into the use of a statistical approach to band sharing 

opportunities should be continued and extended to include full consideration of 

operational and technical requirements of radar services. 

Recommendation 3.12: The use of 3D radars in ATC applications should be considered 

for long term R and D. Studies into the cost and benefits, operational validation and 

methods of funding should be reviewed. 

Recommendation 3.13: Increased standardisation of primary radar characteristics 

should be considered as a means for improving spectral efficiency and increasing 

compatibility with potential band sharing services. Improved spectrum utilisation 

characteristics should be a standardisation objective. Standardisation could be carried out 

by industry bodies such as EUROCAE for technical standards or by EUROCONTROL for 

operational standards. Global aspects would require the involvement of ICAO. It is 

considered that increased standardisation would achieve operational benefits as well as 

spectrum utilisation benefits. 

Recommendation 3.14: Band sharing should only be contemplated in a fully regulated 

environment. 

3.3 Secondary Radar (L-Band Secondary ATC) 

3.3.1 Introduction 

Whereas primary radar (reviewed in section 3.2) provides surveillance on all targets, 

secondary surveillance radar (SSR) relies on cooperation from the target in the form of 

equipage with a suitable transponder. Since civil aircraft operating in controlled airspace 

are required to be suitably equipped and since SSR provides additional data compared 

with primary radar (including altitude and identity), SSR provides the principal means by 

which air traffic controllers obtain a “picture” of the location of aircraft under their control. 

It is therefore an essential safety critical service for air traffic control. 

This section reviews the key issues associated with SSR: 

• The upgrade of current SSR to a new “Mode S” operating in the same band in 

the period up to 2010 leading to benefits of reduced RF interference and support 

for increased traffic levels; 

• The range of other systems using the same band, including ACAS and 1090 

squitter, leading to potential saturation of the band for some services some time 

after 2010; 

• The potential for ADS-B based on 1090 squitter to replace some of the services 

currently provided by SSR in the period after 2010; 

• A similar potential for other ADS-B systems in different bands having the 

possible advantage of relieving some of the congestion in L-band. 

3.3.2 Frequency Allocations (International & National) 

SSR uses the 1030MHz and 1090 MHz frequencies world-wide. These frequencies fall 

within the 960-1215MHz allocation by the ITU to ARNS/RNS and primarily used for 

DMEs. 

Page 62

3.3.3 Technology Description 


Secondary Surveillance Radars consist of a ground interrogator and an airborne 

transceiver (which detects the interrogation and produces a reply that is synchronous with 

the interrogation). All SSR installations operate on 1030MHz for the ground-air 

interrogations and 1090MHz for the air-ground reply. The use of different frequencies for 

uplink and downlink ensures that any reflections or echoes to the interrogation signal will 

not interfere with the aircraft’s reply. This overcomes one of the main technical limitations 

of PSR, and explains why SSR has a much better performance than PSR. However, note 

that unlike primary radar, SSR is a dependent system (reliant on airborne equipage of 

transponders), and therefore cannot ‘see’ unequipped airborne traffic. 

The interrogation and control transmissions (on 1030MHz) must have tolerances within 

0.2MHz of the carrier frequency for Mode A/C and ± 0.1MHz for Mode S. The frequency 

tolerance for the reply transmission shall be ±3MHz for Mode A/C and ±1MHz for Mode S. 

SSR is used as a stand-alone system, or co-located and synchronised with primary radar 

(particularly in en-route areas, where all the UK’s primary en-route radars are co-located 

and frequency paired with SSR). It is used in en-route, TMA and on the airport surface 

(normally as part of a multilateration solution). 

3.3.3.2 Technical Description 

The ground interrogator transmits a signal, which is responded to by the aircraft’s 

transponder. The ground then measures the round trip delay of the received signal, and 

extracts data from the aircraft transponder reply. Azimuth is measured from the position of 

the rotating radar antennae. 

Figure 3-6 below shows a basic schematic for the operation of SSR. 

Figure 3-6: Secondary Surveillance Radar, showing the pulse data transfer 

The interrogations for Mode A/C can be seen in Fig 3-7 – P1 and P3 are the interrogation 

pulses, with P2 being the control pulse. The P2 pulse is used for sidelobe suppression – 

the P2 pulse is constant, and thus other pulses can be measured against it to ensure that 

the target will only reply when in the main P1/P3 beam. If the P2 pulse returns a higher 

signal level than the P1 or P3 pulse, the target is outside the main beam and will not 

reply. 

Page 63

MODE 

MODE 

8 µs 

P1 P2 P3 

P1 

Interrogations (1030 MHz) 

P2 

21 µs 

P3 

Aircraft responds 

with Identity (Mode A) Code 

Aircraft responds 

with altitude (Mode C) data 

Figure 3-7: 1030MHz interrogation signals 

In reply, the aircraft transponder sends a 12-bit burst of data (each pulse separated by 

1.45 µs). 

3.3.3.3 Development of SSR 

Secondary Surveillance Radars have increased in complexity over their design lifetime. 

SSR grew out of the military wartime system known as IFF (Interrogate Friend or Foe). 

With IFF, a target picked up by primary radar would subsequently be interrogated by the 

secondary radar and, if it did not give the appropriate response, it would be assumed to 

be hostile. With SSR, the principle is similar except that the transponder may return either 

identity (Mode A) or height (Mode C) information and an unresponsive target is not 

necessarily assumed to be hostile. [Note that the SSR system also includes some typical 

military identification modes: Mode 1, 2, 3 and 4, where Mode 3 is analogous to Mode A]. 

Mode A identity codes suffer from the limitation that only 4096 combinations are possible 

using the pulses available (octal 0000-7777). In modern European airspace, that number 

can prove inadequate; as several aircraft may be assigned the same identity code (their 

origin may be in geographically separated airspace regions, but as the flight progresses, 

two or more of these aircraft may appear via the same SSR). An optional Special Position 

Indicator pulse (SPI) is only set if the pilot activates the IDENT key on his control panel 

(where a controller needs to differentiate aircraft with the same Mode A code). The SPI 

pulse is recognised by ground systems, and an indication is made on the controller 

display. 

Original SSR systems used a technique known as ‘sliding window’ to estimate the 

azimuth of the target. Sliding window interrogators repeatedly send out interrogations, 

and the aircraft’s azimuth can be pin-pointed as the mid-point between the leading and 

trailing edges of the reply (i.e. when it started and stopped responding). This technique’s 

accuracy relies on receiving a relatively high number of valid replies to confirm the 

existence of a target. 

More modern SSR interrogators use a monopulse technique, utilising a pair of differential 

receiving antennas, as shown in Figure 3-8 below. Both antennas receive the reply, and 

by amplitude or phase measurements the azimuth can be calculated. By comparing the 

Page 64

amplitudes of each antenna (calculations of the sum and difference signals from these 

antennas), the azimuth of the aircraft within the beam can be determined from a single 

reply (and theoretically even from one single pulse in the reply). 

Rx A 

Rx B 

Figure 3-8: Monopulse SSR (MSSR) technique 

Monopulse SSR (known as MSSR) therefore has significant advantages over the early 

sliding window methods – it is roughly 4 times more accurate and requires fewer replies. 

This in turn means the interrogation frequency (pulse repetition frequency, or PRF) can 

be reduced, leading to reductions in the overall level of RF interference. Note that the UK 

has already in a previous update cycle replaced its sliding window radar with monopulse 

radar – hence there is little further scope for increased spectrum efficiency. 

In the current environment, three ‘modes’ of SSR can be implemented: A, C and S. Mode 

S is an evolution of conventional MSSR Mode A/C in which more data transfer 

capabilities are added to the system. Mode S enables the selective interrogation of 

aircraft and the extraction of air derived data through which new ATM functionality can be 

developed. It overcomes certain limitations of SSR Mode A/C: 

• The limitations in the number of Mode A identity codes – Mode S uses the hardcoded 

ICAO address of the aircraft for identification – each 24-bit address is 

unique to its aircraft. For identification of the aircraft to the controller, this address 

can then be uniquely correlated with the flight ID which is also down-linked by 

Mode S. 

• Altitude precision – Mode S provides higher altitude precision (from 100ft to 25ft 

increments). 

The standard Mode S level is known as Elementary Surveillance (with ICAO address, 25ft 

altitude increments and position). 

Mode S Enhanced Surveillance consists of Elementary Surveillance supplemented by the 

extraction of airborne parameters known as Downlink Airborne Parameters (DAPs) to be 

used in the ground Air Traffic Management systems. Some parameters are for display to 

controllers, known as Controller Access Parameters (CAPs), and some are for (ATM) 

system function enhancements, known as System Access Parameters (SAPs). 

Mode S has been designed to be compatible with existing technology – i.e. Mode A/C and 

ACAS. Mode S standards are defined in ICAO Annex 10 Volumes III and IV amendment 

73. 

3.3.3.4 SSR Modes 

These definitions from ICAO Annex 10 Volume IV attempt to clarify the various roles of 

each mode. 

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SSR Mode Use 

Mode A Elicits transponder replies for identity (using SSR code – octal 0000- 

7777) and surveillance. 

Mode C Elicits transponder replies for automatic pressure-altitude transmission 

and surveillance. 

Mode A/C/S 1 all call 

(intermode) 

Mode A/C only all 

call (intermode) 

The mode used to elicit replies for surveillance of Mode A/C transponders 

and acquisition of Mode S transponders. 

The mode used to elicit replies for surveillance of Mode A/C transponders 

only; Mode S transponders do not reply. 

Mode S only all call Only Mode S transponders respond. 

Mode S only 

broadcast 

Mode S only 

selective 

interrogation 

To transmit information to all Mode S transponders; no replies are 

elicited. 

For surveillance of, and communication with, individual Mode S 

transponders. For each interrogation, a reply is elicited only from the 

transponder uniquely addressed by the interrogation. 

Table 3-6 – ICAO Annex 10 – Definitions of SSR Modes 

3.3.3.5 Other compatible technologies 

The Airborne Collision Avoidance System (ACAS) provides an airborne picture of nearby 

SSR transponder equipped aircraft to the flight crew, and assists in the collision 

avoidance if necessary. ACAS interrogates SSR Mode A/C and Mode S transponders in 

nearby aircraft, detects the transponders’ replies, and measures the relative range and 

bearing. Using these measurements and the reply data (e.g. pressure altitude), ACAS 

estimates the relative position of each responding aircraft, and predicts a track for that 

aircraft. The RF characteristics of all ACAS signals comply with their SSR equivalent. 

Multilateration and 1090 Extended Squitter are also likely to be introduced in European 

airspace in the near future (initial local implementations have already started). See 

section below on new technologies in-band (3.3.7). 


3.3.4.1 Overview of operational requirements 

The operational requirements for SSR stem from the need to have an accurate method of 

determining aircraft position in ‘gate-to-gate’ operations. From the airlines’ viewpoint, they 

want to get from departure to destination as safely and efficiently as possible. To do this, 

Air Traffic Controllers provide a dual service: 

• To provide safe separations for all aircraft under their control; 

• To ensure the orderly and efficient conduct of flights. 

The controller must know aircraft position at all times during the flight (when in controlled 

airspace), and must be able to identify uniquely an aircraft. Although PSR provides 

independent radar coverage near airports, in the en-route environment its performance 

does not meet requirements (i.e. inadequate positional accuracy, allied to no unique 

identification methods). SSR is used to track all transponder-equipped aircraft in en-route 

airspace (much of the UK’s airspace is only available to such aircraft), and allows 5nm 

1 

Note that Mode A/C/S is a mode which can support Mode A, Mode C and Mode S 

functions. 

Page 66

separation minima to be achieved due to the high relative accuracy, integrity and 

availability. 

Therefore, a mandate for SSR equipage exists throughout European airspace. Indeed, for 

safety and redundancy reasons, dual coverage of SSR is required throughout the core 

en-route area of Europe. In TMAs, SSR and PSR coverage is required. 

Mode S Elementary Surveillance has replaced MSSR in 6 core European States (not 

including the UK) since 2002. Mode S Enhanced Surveillance is proposed to be 

implemented in France, UK and Germany from 2005 (mandatory equipage of the 

commercial fleet), with all aircraft equipped by 2008. The following quote from 

EUROCONTROL’s Mode S Programme states the uncertain situation that Mode S 

Enhanced Surveillance is in: 

“Mode S Elementary Surveillance will be introduced in many ECAC States; its selective 

interrogation capability will overcome the limitations on the current SSR systems, allowing 

capacity to continue to increase in a safe and efficient manner. The Provisional Council 

has approved the implementation of Mode S Elementary Surveillance. Some users are 

not convinced about the relevance of Mode S Enhanced Surveillance and therefore have 

held up Provisional Council (PC) approval so far.” 

The CAA has initiated separate Regulatory Impact Assessments (RIAs) 2 for both the 

proposed implementation of Mode S Enhanced Surveillance for IFR GAT flights in 

designated TMA and En Route airspace from 31 March 2005 and for the implementation 

of Mode S elementary surveillance for flights elsewhere from 31 March 2008. These RIAs 

are now at the second stage of consultation. 

ACAS also uses SSR signals to track and avoid collision with other transponder equipped 

aircraft. 

Future systems have also been designed (and are currently being tested in preoperational 

trials) to follow-on from Mode S (using the same transponders). 1090 

Extended Squitter (a broadcast datalink) will broadcast over the same frequency 

(1090MHz), and decisions have been taken in the US and Europe to use this datalink to 

introduce airborne surveillance (via ADS-B). As such, Airbus and Boeing are intending to 

equip their aircraft to support the broadcast of 1090ES by 2005. 

Users (particularly ANSPs) will be required to make decisions on whether to target Mode 

S Enhanced Surveillance or 1090ES (or both) in the medium term. Both technologies 

deliver aircraft derived data for use in ground tools, and both therefore bring significant 

benefits over current systems. However, these benefits will only mature in synch with the 

development and implementation of ground tools that will use them. At present, the lack 

of tools to use the additional data beneficially is one of the major barriers to any decision 

being made by the users. It is understood that NATS is considering an initial 

implementation of controller tools which will use Mode S derived data and provide some 

airspace capacity benefits. 

2 An RIA is a policy tool that assesses the impact, in terms of costs, benefits and risks of 

any proposed regulation. It is intended to improve the quality of advice to Ministers and 

encourages informed debate. Part of the RIA process is to conduct full public 

consultation. 

Page 67

3.3.4.2 Summary of operational requirements on spectrum 

Even though there is some discussion over which technology will be implemented in-band 

in the future, it is clear the frequency will continue to be congested for the foreseeable 

future. Within the UK, NATS and the CAA do not foresee the decommissioning of SSR. 

As the load on the frequency is in part proportional to the traffic density in the coverage 

area, this will have a bearing on the frequency requirements. Traffic is expected to 

increase steadily over the next 10-15 years, with a doubling of the current European 

traffic levels predicted by 2015. 

There may be a requirement for ground-based surveillance accuracies to be increased in 

the future. In particular: 

• There is a need for more consistent surveillance accuracy (currently, the impact 

of a fixed azimuth accuracy leads to increased errors at long range); 

• There is a potential need for increased accuracy should there be a need to 

decrease separation minima. 

These requirements may lead to further developments and implementation of SSR. 

However, it is also possible that these requirements could be met by ADS systems based 

on the superior accuracy available from GNSS. The downlinking of aircraft parameters 

(via 1090ES or Mode S Enhanced Surveillance) may also play a vital role in this. 

As such, the operational requirements on the spectrum will increase in the next few years, 

mainly due to the increase in SSR replies. 

The UK SSR environment is managed by the National IFF/SSR Committee which reports 

to the UK Spectrum Strategy Committee. Modelling and interference investigations are 

used to monitor interference. The IFF/SSR Committee reports to the UK Spectrum 

Strategy Committee. According to the CAA, the results of the modelling and interference 

investigations support the view that increased use of Mode A/C will adversely affect the 

integrity of the SSR frequencies. This view is supported by work conducted in Germany 

and other States. Due to the proliferation of SSR systems for ATC purposes and the 

increasing use of ACAS systems, the SSR frequencies are in danger of becoming 

saturated. This causes an increase in interference, which in turn is leading to a 

consequent decrease in the probability of replies received. Through selective addressing, 

Mode S reduces the number of replies being made and therefore reduces RF pollution. 

Therefore, the drive within the UK is to implement Mode S as a means of ensuring that, 

through the control of interference, future operational requirements can be met. 

Furthermore, since the events of September 11 th , security issues have become more 

important. In particular, the ongoing need for a secure surveillance system. In this 

respect, SSR has an advantage over the alternative ADS-B systems, where surveillance 

relies on self-location by the aircraft and, in some cases, air to ground communication 

which may be more vulnerable than is the case for L band systems. 

It is worth noting that the number of interrogators will not significantly change; the uplink 

frequency of 1030MHz will therefore have scope for improvement (at present, it is 

underused). 


3.3.5.1 In-Band Technical Regulation – ICAO SARPS – Annex 10 Vol IV, 

Chapters 2, 3 and 4. 

The ICAO SARPS are well developed for SSR, and include a range of regulatory features 

designed to protect and enhance the frequency use. The following table presents a 

Page 68

summary of the most relevant standards, regulations and recommendations from Annex 

10. 

Reference Standard or regulation 

2.1.2.1.1 “Administrations should coordinate with appropriate national and 

international authorities those implementation aspects of the SSR 

system which will permit its optimum use. 

Note – In order to permit the efficient operation of ground equipment 

designed to eliminate interference from unwanted aircraft transponder 

replies to adjacent interrogators (defruiting equipment), States may 

need to develop coordinated plans for the assignment of pulse 

repetition frequencies (PRF) to SSR interrogators.” 

2.1.2.1.2/3 The assignment of interrogation and surveillance identifier (II and SI) 

codes should be subject to regional air navigation agreements in areas 

of overlapping coverage. 

2.1.2.4 Side-lobe suppression shall be provided on all interrogations. 

3.1.1.4.6 The lower limit of rise-time for pulses (0.05 µs) is used to reduce 

sideband radiation. 

3.1.1.7.4 Suppression – to prevent replies to interrogations received via the 

sidelobes of the interrogator antenna and to prevent Mode A/C 

transponders replying to Mode S interrogations – shall be applied when 

the P2 pulse has greater amplitude than P1. 

3.1.1.7.9.2 “Reply rate limit control. To protect the system from the effects of 

transponder over-interrogation by preventing response to weaker 

signals when a predetermined reply rate has been reached, a 

sensitivity reduction type reply limit control shall be incorporated in the 

equipment.” 

3.1.1.8.1.1 “Recommendation – To minimize unnecessary (Mode A/C) 

transponder triggering and the resulting high density of mutual 

interference, all interrogators should use the lowest practicable 

interrogator repetition frequency that is consistent with the display 

characteristics, interrogator antenna beam width and antenna rotation 

speed employed.” 

3.1.1.8.2 “Recommendation (Mode A/C only) – In order to minimize system 

interference the effective radiated power of interrogators should be 

reduced to the lowest value consistent with the operationally required 

range of each individual interrogator site.” 

4.3.2.2 A range of interference controls are applied to ACAS including radiated 

power, interrogation rate, and changes in power due to density of 

surrounding equipped traffic. 

Table 3-7 SSR Considerations 

Table 3-7 above indicates the strenuous efforts that have been undertaken to make the 

most efficient use possible of the two channels allocated to SSR. 

Spectrum limits are also applied to each of the modes. Figure 3-9 below (taken from 

Annex 10) shows the regulation applicable to SSR Mode S transmissions. 

Page 69

Figure 3-9: Required spectrum limits for Mode S transponder transmitter 

3.3.5.2 Out-of-band (OoB) Regulation 

Both SSR and ACAS are ‘safety-of-life’ systems, meaning that frequency protection is 

vital. In practice, this entails regulation and standardisation of ARNS in neighbouring 

channels (e.g. DME). 

SSR frequencies fall in the middle of ITU’s allocation to ARNS (960-1215MHz). As such, 

regulation that takes place is between aeronautical regional navigation services. In 

particular, the siting of DMEs and their equivalent frequency setting must be considered, 

so as to maintain the strict protection from OoB interference in the 1090/1030MHz bands. 

The military also has applications in this band (960-1215MHz) – military identification 

systems (some of which ‘frequency-hop’) such as JTIDS (Joint Tactical Information 

Distribution System) are the best examples. However, any such use is secondary to the 

primary purpose of the band (ARNS), and strict regulations guarantee minimal 

interference from these systems. 

3.3.5.3 Summary of regulation 

ICAO’s position is to recommend the reservation of the two frequencies for the 

foreseeable future and this view appears to have general support from other aeronautical 

stakeholders (i.e. airlines, service providers etc). 

Page 70

Co-ordination of PRF (pulse repetition frequency) on a national basis is required for 

overlapping coverage areas of SSR. Essentially, this means tailoring the pulse rate to 

factors such as: the technology of the SSR (Mode S, MSSR, Mode S Enhanced 

Surveillance); the coverage required; and the SSRs in the vicinity. Allied to plot plan 

processing techniques, this should assist in reducing the number of invalid responses 

being processed by the ground system. 

3.3.6 Possible Improvements to existing technology 

The development of monopulse SSR (MSSR) has led to a reduction in the FRUIT levels 

throughout Europe. Its implementation highlights an issue for the development of the 

technology – many monopulse radars only supplemented their ‘sliding window’ equivalent 

when the existing radar was due to be replaced. 

Partly for this reason, mandates have been imposed by several States (Belgium, France, 

Germany, Luxembourg, the Netherlands and Switzerland) for Mode S Elementary 

Surveillance. The UK has plans for the implementation of Mode S SSR ground stations 

across its coverage area in the period up to 2010. An AIC has been circulated advising 

users of a possible mandate for Mode S Enhanced Surveillance in the 2005+ timeframe 

(along with France and Germany) and the CAA has initiated separate Regulatory Impact 

Assessments (RIAs) 3 for both the proposed implementation of Mode S Enhanced 

Surveillance for IFR GAT flights in designated TMA and En Route airspace from 31 

March 2005 and for the implementation of Mode S elementary surveillance for flights 

elsewhere from 31 March 2008. These RIAs are now at the second stage of consultation. 

This gradual shift from MSSR Mode A/C to Mode S should mean a reduction in the RF 

interference level. The use of selective addressing (and lockout protocols) mean that 

interrogations happen only once per cycle with Mode S (decreasing the second replies 

and FRUIT). Also, use of the ICAO 24-bit address, which can be correlated with the Flight 

ID, means that each aircraft is uniquely identified, leading to less confusion and possible 

extra transmission of SPIs (special position indicator). 

However, Mode S Enhanced Surveillance, as is planned in France, Germany and the UK 

by 2005, will include a greater amount of data extracted from the transponder in the form 

of Downlinked Aircraft Parameters (DAPs). The development of ADS-B (1090ES) may 

make this redundant (as the information could be broadcast from the aircraft), but the 

level of in-band interference will still be affected. 

In summary, the technology in the short-term will improve, leading to a more efficient use 

of the available spectrum. However, as extra data is transmitted over the frequency and 

the traffic density increases in the medium-term, in-band efficiency may decrease to a 

level unsustainable for some ‘safety-of-life’ applications. 

3 An RIA is a policy tool that assesses the impact, in terms of costs, benefits and risks of 

any proposed regulation. It is intended to improve the quality of advice to Ministers and 

encourages informed debate. Part of the RIA process is to conduct full public 

consultation. 

Page 71

Parameter Value Notes 

Service topology Point-to-point This is a Mode S Specific Service. 

Data collection is optimised thanks to an asynchronous 

mechanism: on the air side, data extracted from the avionics 

busses are periodically polled to refresh dedicated Mode S 

transponder’s memory register. On the ground side, data 

extraction through the Mode S link is initiated when required 

according to ground users’ requests. 

Aircraft data allocation to the transponder’s memory is predetermined/standardised 

by ICAO doc 9688. 

The retained parameters for initial implementation of Mode S 

enhanced surveillance in Europe are the following: 

1) For CAP D/L service: Magnetic Heading, IAS/Mach nr 

2) For CAP & SAP: Selected Altitude 

3) For SAP: Vertical Rate, Track Angle Rate, Roll Angle, 

Ground Speed, True Track Angle 

These data fit into 2 Mode S GICB registers (BDS 50/60). 

Wind vector, as required by ODIAC/CAP, would require a 

third register to be extracted (BDS 44) 

For Mode S Specific Protocol (MSP): 

Limited addressing at the application level with 63 channels 

available. Non-connected mode, no flow-control mechanism. 

ATN compliance No 

Frequency band 1030, 1090 

MHz 

RF Channels Two distinct 

channel 

Modulation 

scheme 

DPSK and 

PPM 

Bit rate Uplink: 4 Mb/s 

Downlink: 1 

Mb/s 

Channel access 

method 

Frequency 

availability 

(allocation 

status) 

Managed via 

Mode S 

interrogation 

scheduling 

Frequencies 

available. 

1030 MHz for uplink transponder interrogations 

1090 MHz for downlink replies 

Uplink: Differential Phase Shift Keying (DPSK) 

Downlink: Pulse Position Modulation (PPM) 

Note: Data transfer is only available during the beam dwell; 

hence effective data rate for a 6 second rotation is 

approximately 600 bps. 

Access is managed according to air situation (in order to 

reduce interference/FRUIT) and user demand for GICB 

transactions. 

Global allocation of 1090/1030 MHz to SSR and Mode S 

systems 

1030/1090 RF channels are also used by: classical SSR 

Surveillance, Mode S elementary surveillance, Mode S 

squitter & ACAS, Mode S extended squitter, and other Mode 

S data services described above. Mode S elementary 

surveillance is a pre-requisite for Mode S datalink; It can be 

anticipated that the available bandwidth in the antenna’s 

beam for a given aircraft will be shared between Mode S 

Enhanced Surveillance and SVC/MSP. However, the impact 

of the deployment of Mode S Enhanced surveillance on 

critical systems/services like Mode S elementary 

surveillance, ACAS II and 1090ES/ADS-B/TIS-B/ASAS are to 

be assessed. Also used by military IFF system. 

Page 72


Dependencies UTC 

synchronisatio 

n is required in 

ground 

stations to 

enable time 

stamping of 

collected 

aircraft data 

Data in the Mode S transponder’s registers does not include 

timestamps 

Table 3-8: Mode S summary 

3.3.7 Possible New Technologies (in-band) 


New technologies operating on the same frequency include new uses of the same data, 

and developments of existing concepts. Multilateration and 1090 Extended Squitter are 

two systems likely to be introduced in the next few years. 

3.3.7.2 Multilateration 

Multilateration is a triangulation technique whereby SSR signals sent from an aircraft are 

received at several ground sensors in the vicinity (normally, airport surface). A 

measurement is made of the difference of the ‘time-of-arrival’ (TOA) of each signal at 

each sensor by a central computer. The time difference of arrival can then be used to 

accurately determine the location of the origin of the signal (i.e. aircraft). Three ground 

sensors enable a 2-D position to be determined; four or more sensors enable a 3-D 

position measurement, as well as greater accuracy in the 2-D position measurement. 

3.3.7.3 1090MHz Extended Squitter 

The 1090 MHz Extended Squitter (1090 ES) is an extension of Mode S technology. A 

number of extended squitters are transmitted at a high rate (five times a second). Each 

message consists of 112 bits, 24 bits of which are used for parity. The data rate used is 

one megabit per second, within a message. Access to the 1090 MHz channel is 

randomised, and the channel is shared with Secondary Surveillance Radar (Mode A/C 

and Mode S) and the Airborne Collision Avoidance System (ACAS). 

1090 ES provides air-air, air-ground and ground-air broadcast services (i.e. ADS-B – 

Automatic Dependent Surveillance- Broadcast and TIS-B - Traffic Information Services - 

Broadcast). A complementary uplink broadcast service could be provided at 1030 MHz 

i.e. the SSR interrogation frequency. 

Numerous simulations have been conducted by the FAA and UK Civil Aviation Authority 

to ensure that 1090 ES does not have an adverse effect on the ACAS and SSR. These 

simulations show that 1090 ES can operate along side these other systems. 

1090 ES enjoys support from the FAA and some European ANSPs. Support in Europe is 

considered ‘medium’. 

The risk in developing 1090 ES into an operational system is considered low. Certifiable 

equipment already exists which is very close to the anticipated final requirements for 1090 

ES. 

For air-air surveillance 1090 ES could be used in all airspace types. For air-ground 

surveillance, 1090 ES requires a relatively high density of ground stations and is therefore 

not suitable for oceanic and remote areas. 

Page 73

The coverage available from a 1090 ES ground station is very dependent upon the 

density of traffic and local deployment of other systems (ACAS, Mode S) operating in the 

same frequencies. Coverages of up to 40nm are thought to be possible up to 2010. 

Beyond 2010, the levels of FRUIT (false replies) on the 1090MHz band are thought to 

significantly reduce the performance of the datalink. 

The modulation of the ADS-B message transmission is Pulse Position Modulation (PPM). 

Airborne terminal design 

The layout of the airborne 1090 ES system is illustrated below. 

Transmitted 

extended squitters 

Received 

extended squitters 

Top and bottom 

Mode S antennas 

TCAS 

Antennas 

Mode S Transponder 

TCAS 

(ATN router) 

Barometric altimeter 

Avionics systems 

(FMS, CDTI, etc) 

256 BDS registers 

including 6 

extended squitter 

Figure 3-10 – 1090 ES Airborne Architecture 

1090 ES messages are contained in Binary Data Store (BDS) registers. Six of the 256 

BDS registers in the Mode S transponder contain extended squitters. These registers are 

frequently updated by the avionics systems. 

The extended squitter registers are transmitted at frequent intervals autonomously by the 

transponder and can also be extracted by a request from a ground interrogator. If an 

extended squitter BDS register is not updated for 2 seconds, then it is cleared by the 

transponder, thus preventing the transponder transmitting out-of-date information. 

Standards 

The SARPs for the Extended Squitter have been agreed by ICAO SICASP (Secondary 

Surveillance Radar Improvement and Collision Avoidance Systems Panel) and are 

included in the latest issue of ICAO Annex 10. 

ICAO SICASP has also published the Manual of Mode S Specific Services, Doc 9688 in 

1997. EUROCAE has developed MOPS for a Mark 4 Mode S transponder. The 

characteristic defines the installation and inputs required to supply the aircraft data for use 

by the transponder, and include the Extended Squitter functionality. This document has 

also been published. 

RTCA has developed “1090 MHz MOPS” which also define the message formats and 

protocols for Mode S Extended Squitter. This was published in January 2001. 

The AEEC (Airlines Electronic Engineering Committee) has developed an ARINC 

characteristic (ARINC 718) that defines the “form and fit” (i.e. the physical 

Page 74

interconnections, plugs, pin layouts, etc) of the required Mode S transponder avionics. 

This does not yet include the required functionality for the extended squitter. 

There is some overlap between several of the above standards. The most recent 

standard and the main reference are the RTCA 1090 MHz MOPS. It is intended that other 

standards will be adjusted to reflect this one. 

Simulation Results 

In terms of ADS-B performance, the most influential simulations were conducted by 

TLAT. These simulations used both VOLPE and SIEM models. 

The results tend to indicate that: 

• 1090 ES has a limited capacity to support FIS-B; 

• 1090 ES does not support long range air-air applications (> 90 nm); 

• 1090 ES will support short range air-air applications (

Operational Use 

Although many large aircraft are equipped with a minimum Mode S capability, this does 

not include the Extended Squitter function. A very small number of commercial aircraft 

have already been upgraded to transmit extended squitter. British Airways have six such 

aircraft. 


Service topology Air-ground 

datalink, Air-air 

broadcast, 

Uplink 

broadcast, 

Downlink 

broadcast 


1090 MHz Extended Squitter includes a ‘crosslink’ for ACAS, which 

is a simple data link 

Frequency band 1090 MHz Complementary uplink broadcast service could be provided at 1030 

MHz. 

RF Channels Single. One channel at 1090 MHz provides air-air, air-ground and groundair 

broadcast services. 

Modulation 

scheme 

PPM Pulse Position Modulation 

Bit rate 1 Megabit/sec 


method 

Frequency 

availability 

(allocation status) 

Random 

Frequencies 

already 

allocated and 

available. 

Mode S operates on 1030 MHz and 1090 MHz. International 

spectrum allocation of the required 3 MHz channel exists. No further 

actions are required to secure suitable frequencies. 

Dependencies No Not dependent upon the deployment of other technologies. 

May impact on other systems operating at the same frequency – 

ACAS and SSR (Mode A/C and Mode S) 

Other issues Security issues and potential vulnerabilities still to be assessed by 

the aeronautical community. 

Table 3-9: 1090ES summary 

3.3.8 Replacement Technologies (radio, other or none) 


The possible introduction of competing ADS-B datalinks on other bands (e.g. VDL Mode 4 

in the VHF band; UAT probably at 978MHz) may reduce the reliance on 1090MHz 

Extended Squitter datalink, thus freeing up some of the channel. This introduction will 

depend on the uptake of ADS-B in Europe, in particular the airlines’ view of the benefits 

accrued. 

The uptake of ADS-B also depends on airline and ANSP economics. Economies of scale 

have meant that 1090ES is the preferred solution for the short-medium term (with aircraft 

already mandated to equip with Mode S transponders). VDL Mode 4 is a viable 

alternative, but requires a separate on-board transponder. 

VDL Mode 4 also provides a point to point communication service – details are given in 

section 4. Details on UAT are given below. 

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3.3.8.2 UAT 

The Universal Access Transceiver (UAT) is the result of an internally funded project at 

MITRE/CAASD in the US, started in December 1994 to develop and demonstrate a 

transceiver system designed specifically to support the function of ADS-B. UAT has been 

developed to a prototype status and is being trialled in the US. 

In addition to ADS-B, UAT is intended to support uplink broadcast data from ground 

stations. This could include TIS-B and/or FIS-B data. Note that UAT only supports 

broadcast applications and not point to point applications. 

The UAT prototype operates in a single channel with a bandwidth of approximately 2-3 

MHz, using the same frequency for transmit and receive. All aircraft access the channel 

autonomously at random, and there is no centralised ground control or on-board logic for 

this function. 

The first UAT prototype operated with experimental authorisation at 966MHz, which is in 

the range used for DME (960-1215 MHz). The large scale trials presently underway in 

Alaska (“Capstone”) operate at 981 MHz. The channel that will be used in a final 

operational system is not yet fixed. Within the US, the FAA has initiated procedures to 

secure a permanent frequency assignment. 

UAT has been specifically designed to provide air-air, air-ground and ground-air 

broadcast services. 

UAT does not provide point-to-point functionality. 

System description 

UAT messages are transmitted using continuous phase frequency shift keying. Data is 

transmitted at a rate just over 1 Mbit/sec (precisely 1.041667 megabit/second), thus each 

bit period is 0.96 microseconds. 

In the UAT system, the ‘frame’ is the most fundamental time unit. Frames are one second 

long and begin at the start of each Universal Time Coordinated (UTC) (or GNSS) 

second 4 . Each frame is divided up into two segments – one for ground station 

transmissions and another for mobile station transmissions (aircraft or surface vehicle). 

Each segment is further subdivided into message start opportunities (MSOs) spaced 250 

ms apart for a total of 4,000 MSOs per frame. The MSO is the smallest time increment 

used for scheduling Ground Uplink messages or ADS-B message transmissions. 

4 UTC is a global standard for time which was defined by the International Consultative 

Committee (CCIR), a predecessor of the ITU-T. CCIR Recommendation 460-4, or ITU-T 

Recommendation X.680 (7/94) contains the full definition. The UTC second can be 

obtained from GPS or, more generally, GNSS signals. 

Page 77

Ground broadcasts 

(188 ms = 752 MSOs) 

Timeslot consists 

of 22 MSOs 

(5.5ms) 

Ground message 

(3712 bits payload) 

Ground station messages are 

synchronised to timeslots. 

Timeslot usage is planned so 

ground station transmissions 

do not overlap. 

UAT frame of 1 second 

ADS-B reports from aircraft 

(812 ms = 3248 MSOs) 

ADS-B message 

(128/256 bits payload) 

Message Start 

Opportunities 

(MSOs, 250 µ s) 

Aircraft ADS-B reports are synchronised to an 

MSO if the aircraft has an accurate time 

reference available. 

MSOs are selected randomly by aircraft. 

Figure 3-11 – UAT timing structure 

= Guard time of 48 MSOs (12ms) 

Ground transmissions 

The first segment of the frame is allocated to transmissions from UAT ground stations and 

consists of 752 MSOs (Message Start Opportunities). This portion of the frame contains 

32 time-slots, each containing 22 MSOs and therefore lasting 5.5 ms, with a guard time of 

48 MSOs at the end of the frame. 

Each ground station is assigned one of the 32 time-slots in such a way that transmissions 

from nearby ground stations can be received without interference. Each ground station 

transmits a ground broadcast message once each second, starting at the beginning of its 

assigned slot. 

ADS-B message transmissions 

The second segment of the frame is devoted to ADS-B message transmissions. Within 

this portion of the frame, aircraft and surface vehicles are required to transmit at randomly 

selected times from among the 3200 MSOs in the segment. The selection algorithm is 

designed to prevent any two stations from repeatedly selecting the same MSO. Aircraft 

messages may contain 128 or 256 bits of ADS-B data (payload). 

A substantial guard time, specifically for timing drift, is accommodated at both the 

beginning and the end of an ADS-B segment. This allows for clock drift in airborne units 

for a period of time before there would be any possibility of ADS-B transmission overlap 

with a ground message. 

UAT, like VDL4, needs a source of precise time to ensure that it is aware of the timeslot 

structure to which it should adhere when transmitting messages. The source could most 

easily be a GNSS receiver. However, in the event of loss of the timing source, a mobile 

UAT receiver may make timing measurements on ground station signals to determine 

timing information. 

Exactly one ADS-B message is transmitted per aircraft every second. An ADS-B message 

is either 252 or 380 bit intervals in length. 

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Figure 3-12 shows the format and components of the ADS-B message burst transmission 

from aircraft (or ground vehicles). 

number of bits: 

Tx power stabilisation 

Synchronisation 

Length identifier 

4 36 

8 128/256 24 48 4 

ADS-B data 

(‘payload’) 

Tx ramp down 

Forwarded Error Correction 

Cyclic Redundancy Check 

Figure 3-12 – UAT ADS-B message transmitted from aircraft/ground vehicle 

UAT is the only one of the ADS-B data link systems to incorporate a Forward Error 

Correction (FEC). This gives it increased robustness to bit errors that may occur in the 

message since a small number of these can be corrected. The Cyclic Redundancy Check 

(CRC) is still applied following any corrections by the FEC. This maintains the integrity of 

the message. 

The UAT message set is defined with a “Basic” Message that includes only State Vector 

information, and a set of 3 “Extended Length” Messages (types 0, 1, 2) that each include 

the State Vector plus other variable information required by the RTCA MASPS. In trials 

(e.g. the Capstone trial), aircraft were configured to only transmit the basic and extended 

type 0 messages. 

The ADS-B message transmission rate for UAT is fixed at once per second. This rate has 

been designed to support all applications identified in RTCA DO-242. 

Airborne terminal design 

Different airborne terminal configurations are possible depending on the class of aircraft. 

The configuration illustrated in. Figure 3-13 may be sufficient for low-end general aviation 

users. 

T/R 

UAT transceiver 

GPS time/position sensor 

& altitude source 

ADS-B Reports 

TIS-B, FIS-B 

Application 

processor(s) 

CDTI and 

surveillance 

functions 

Figure 3-13 – UAT Low-end Airborne Architecture 

A processing unit linked to the transceiver processes data from ADS-B reports and 

external data sources such as TIS-B and FIS-B, and provides surveillance reports and 

track data to the CDTI and other surveillance functions. 

Under normal conditions it is expected that the UAT transceiver would interface with a 

GNSS sensor and barometric altitude source for a minimal installation. The GNSS sensor 

would provide the position and velocity information as well as timing for ADS-B 

Page 79

transmissions. These sources of aircraft data would also provide information to the CDTI 

and other surveillance functions about the aircraft’s own position and status. 

Air transport category aircraft may carry dual UAT transceivers; each connected to the 

application processor(s) and the GNSS time/position and altitude sources. 

Standardisation 

An RTCA UAT MOPS has recently been completed. 

An AMCP Working Group of the Whole meeting in May 2002 decided to initiate SARPs 

development of UAT, a move supported by the FAA. 

AEEC (ground station) standardisation has not been initiated. 

Demonstration 

TLAT and subsequent simulations have shown that UAT is able to meet all ADS-B 

requirements (except that surface applications have not been evaluated). 

The FAA conducted initial trials of UAT in the Ohio Valley, known as OpEval, as part of 

the FAA’s Safe Flight 21 programme. This work was reported in two phases, OpEval-1 

and OpEval-2. FAA trials are continuing with the Alaska Capstone programme. 

Capstone is a joint initiative between the FAA and US industry. It is evaluating ADS-B 

applications through trials conducted in the Alaska region. There are 150 aircraft 

equipped with UAT avionics including: GNSS navigation receiver, ADS-B 

transmitter/receiver, moving map display with TIS-B traffic and terrain advisory services, 

FIS providing weather maps etc. and a multi-function colour display (CDTI). There is a 

network of 12 ground stations providing redundant coverage of ground stations. UAT is 

also being used to provide cooperative radar-like services. 

A UAT trial was conducted in Paris in October 2000, organised by EUROCONTROL with 

the participation of the FAA Safe Flight 21 Programme, Mitre, and UPS Aviation 

Technologies. UAT operation was tested in the 966 MHz channel, which is currently 

unused in France. 

Page 80


Service 

topology 

ATN 

compliance 

Frequency 

band 

Air-air 

broadcast, 

Uplink 

broadcast, 

Downlink 

broadcast 

No 

960-1215 MHz 

RF Channels Single 1 MHz 

channel 

Modulation 

scheme 

Binary GFSK 

+/- 312.5 kHz 

Bit rate 1.041667 

Mbit/s 

Channel 

access 

method 

Frequency 

availability 

(allocation 

status) 

Dependencie 

s 

Currently no frequency globally available 

Random Slots Ground Stations use separate slots in a predefined manner. 

No operational 

frequencies 

currently 

allocated. 

Earliest 

availability: 

2006 (may be 

longer in 

Europe) 

UTC time 

source 

Europe and the US are converging on the 978 MHz frequency. 

Analysis shows that a UAT assignment at 978 or 979 MHz is 

possible in the US. These frequencies are used in the US for 

testing purposes, and there are no operational assignments in 

that US at either frequency. 

Analysis of the utilisation of the frequencies 978 and 979 MHz in 

Europe shows that a number of DME and TACAN assignments 

exist in Europe at these frequencies: 6 assignments at 978 MHz 

and 50 assignments at 979 MHz, suggesting 978 MHz as a 

possible candidate for UAT. 

The deployment of UAT requires international co-ordination to 

obtain a 3MHz channel in the DME band. Whilst a suitable 

frequency seems likely to be available in America, the European 

situation is more complex. 

The ECAC Navigation Strategy foresees the long-term use of 

DMEs to support GNSS in providing a harmonised area 

navigation (RNAV) environment. 

This will require significant deployment of new DMEs in Europe, 

in particular within terminal areas. The current estimate is that 

180-200 new DMEs will be required by 2010. 

Requires an accurate source of UTC time, nominally from a 

GNSS receiver (which may be a GPS receiver) 

Other issues Security issues and potential vulnerabilities still to be assessed 

by the aeronautical community. 

Table 3-10: UAT summary 

3.3.8.3 Prospects for ADS-B implementation 

ADS-B provides a possible alternative to Mode S SSR providing position and other data. 

The UK current surveillance programme involves replacement of the current SSR with 

Mode S phased over the period 2003 – 2010. Hence there is little prospect that ADS-B 

for air/ground surveillance will be a viable alternative in the short and medium term. In the 

Page 81

longer term, there may be a requirement to provide air-ground applications so as to 

provide enhanced accuracy position data. 

The main opportunity is for ADS-B to support new air traffic control applications which 

require air to air surveillance. Many new applications are being developed and validated 

and there is operator pressure to introduce an initial batch known as “Package 1”. It is 

expected that ADS-B in core European regions will initially be supported by 1090 ES 

since the transponders will be in place because of the Mode S mandate (noting that 

further adaptation of the transponders will be needed to support ADS-B applications). 

Hence there is a marginal cost business case driving this choice but it will be important to 

ensure that the required applications still operate under levels of increased interference. 

However, from the spectrum utilisation point of view, neither UAT nor 1090 ES are good 

choices: 

• both systems are based on random transmissions and hence there is inefficient 

use of the available spectrum; 

• 1090ES operates in a crowded band and there is the expectation that medium 

and long range air to air applications will not be capable of being supported. 

The third candidate, VDL Mode 4, has the advantage of using an organised channel 

access scheme and hence appears to be a much more efficient user of spectrum. For 

example, a recent EUROCONTROL study showed that ADS-B requirements could be fully 

met at short, medium and long range for representative traffic levels on four 25 kHz VHF 

channels. This compares to rather limited performance for 1090ES operating within 

1MHz of spectrum. The drawbacks of VDL Mode 4 include its need to operate in the 

already congested VHF spectrum, the additional cost of fitting VDL Mode 4 transponders 

and a general lack of industry consensus on the business case for VDL Mode 4. 

3.3.9 Allocation Sharing Opportunities 

There are not likely to be further technologies allocated to the 1030/1090MHz frequency 

pair, due to the RF interference levels in-band, allied to the criticality of the applications 

supported by the band. 

However, the military are pressing for increased bandwidth allocation, in particular for 

communications and identification systems such as JTIDS. DAP has granted the military 

use of the 960-1215MHz on a secondary basis – although military needs must be taken 

into account, the 1030MHz and 1090MHz frequencies should be protected from any 

interference from these systems due to their relative criticality. 

3.3.10 Possible Overall Spectrum Efficiency Improvements 

The various technologies presented in this section are summarised in the following table: 

Page 82

Technology Band/Frequency Information 

Mode S SSR 1030/1090 MHz Derivation of position via radar techniques. Data 

link on downlink allows additional aircraft data to be 

obtained 

Airborne Collision 

Avoidance 

System (ACAS) 

1090 MHz System designed to provide short range advisories 

to pilot of potential conflict with another aircraft 

Multilateration 1090 MHz Position location by triangulation using time of 

arrival measurements of transmissions from aircraft 

1090 Extended 

Squitter 

VDL Mode 4 VHF 108/118 – 

137MHz 

UAT 960 – 1215MHz (not 

currently allocated) 

1090 MHz Position and aircraft data from broadcast 

transmissions. Position is determined by the aircraft 

itself (e.g. via GPS) – known as ADS-B 

Alternative ADS-B system operating in VHF band 

Alternative ADS-B system operating in L band 

Uplink on 1030 1030 MHz Possible future system for uplink of data taking 

advantage of relative under utilisation of 1030 MHz 

Table 3-11 Technologies Described 

As traffic density increases across Europe (up by 150% by 2014 according to STATFOR), 

the frequency congestion will in theory increase proportionally, due to the increased 

replies to MSSR, Mode S SSR and ACAS interrogations. 1090MHz (over which 

information is downlinked) is forecast to become saturated by 2010 5 . It is therefore 

imperative that the available channels are utilised to their optimum efficiency. In practice, 

this covers three areas: 

• Out-of-band interference; 

• In-band interference; 

• Cross-channel usage. 

Out-of-band interference is characterised primarily by the allocation of frequencies 

neighbouring 1030 or 1090MHz to DME. 

In-band interference, considering current technology such as Mode S and ACAS, is 

minimised by the statistical analysis of Pulse Repetition Frequencies in SSRs on a 

national scale (to match them to operational requirements, rather than just setting a 

default value). The implementation of Mode S will allow selective addressing (allowing 

single replies, instead of multiple), further minimising the frequency usage. 

Care should be taken with the possible medium term implementation of Mode S 

Enhanced Surveillance (incorporating the downlink of additional parameters, leading to a 

more congested frequency) or 1090ES for ADS-B. Mode S Enhanced Surveillance has 

been subject to an AIC published by the CAA, proposing its implementation by 2008. 

Although dependent on the ground tools available in ATC at that time, recommendations 

should be made not to downlink unnecessary data. 

ADS-B in particular may lead to a swift degradation in the efficiency of the spectrum – 

instead of addressed interrogations (Mode S), ADS-B sends random broadcasts of data 

to all recipients, thus increasing the number of bits sent. Traffic Information Services – 

Broadcast (TIS-B) is a ground-based version of ADS-B operating on the 1090MHz 

5 Assuming the implementation of Mode S enhanced surveillance and 1090ES for ADS-B. 

Page 83

channel, and would further increase the demand on the frequency. Note however that 

TIS-B could in theory operate on the 1030MHz channel (underutilised at present) – here, 

cross-channel usage leads to spectrum efficiency. 

3.3.11 Conclusions and recommendations 

The key developments which influence use of the 1030/1090 MHz frequencies are: 

• The transfer to Mode S from current SSR. As well as a number of operational 

benefits, this provides a reduction in the level of interference and makes it 

possible to maintain SSR services as traffic grows. 

• The implementation of ADS-B services via 1090 extended squitter, which whilst 

offering potential operational benefits, will increase the use of the 1090 MHz 

spectrum and possibly saturate. 

Recommendations 3.15 to 3.17 below apply to the efficient use by SSR of the 1030/1090 

MHz frequencies 

Recommendation 3.15: Ofcom should satisfy themselves that the CAA has taken the 

appropriate steps to ensure that the tailoring of SSR Pulse Repetition Frequencies 

conforms to ICAO recommendations. 

Recommendation 3.16: The implementation of Mode S SSR in the UK should be 

encouraged (allowing selective addressing and potentially fewer replies) coupled with 

implementation of measures to encourage equipage and the appropriate implementation 

of controller tools which use the resulting data. 

Recommendation 3.17: Mode S Extended Squitter implementation – Ofcom should work 

with the CAA in ensuring that data downlinked from the aircraft is not superfluous to 

requirements. In particular this means reviewing the need for regular broadcast of DAPs. 

Socio-economic factors 

Upgrade of the commercial fleet is a costly exercise but one for which there is reasonable 

support. The first stage of upgrade to provide elementary surveillance is already covered 

by a mandate, and this is likely to be extended to cover enhanced surveillance. Hence, 

pricing measures are unlikely to be required. 

Upgrade of GA aircraft is also highly cost sensitive and upgrade is generally resisted by 

the GA fleet. The CAA’s intention is to mandate equipage for elementary surveillance for 

all aircraft by 2008. The costs this will impose on the GA fleet are currently unknown 

although it might be expected to be in the region of £1000 to £3000 6 . This amounts to a 

total GA fleet cost of between £6M and £18M assuming a fleet of 6,200 aircraft. It may be 

necessary to provide support for GA users in order to facilitate the equipage. 

The next two recommendations apply to the introduction of new services on the 1090 

MHz frequency. 

Recommendation 3.18: The 1090MHz channel will be severely constrained in the 

medium term. A review of the future use of this band should be carried out. 

The review should ensure that any new applications meet clearly defined operational 

requirements; if not, studies should be performed to assess the potential benefit against 

6 CAA are currently sponsoring a programme to develop a low cost Mode S/1090 ES capable 

transponder. The target cost, subject to verification by the programme, is below £1000. 

Page 84

the cost to an already saturated channel. The studies should also assess the timescales 

over which the applications will remain effective given that increased traffic will further 

saturate the channel. Crucially, it should be ensured that the introduction of new 

applications does not impact on existing safety of life applications such as SSR and 

ACAS. 

Recommendation 3.19: Ofcom should work with the CAA to evaluate other technologies 

for ADS-B and ensure that spectrum efficient solutions are developed and implemented. 


The introduction of ADS-B via 1090 extended squitter is possible at the same time as 

airborne equipment is upgraded to support Mode S enhanced surveillance. Hence, from 

the point of view of commercial aircraft users, there is marginal cost argument that 

favours implementation of 1090 ES rather than some other ADS-B system such as UAT 

or VDL Mode 4. A EUROCONTROL study analysed costs for the three ADS-B systems 

and concluded that a new installation of VDL Mode 4 or UAT would cost between £30k 

and £40k per aircraft compared with an upgrade of equipment already installed as part of 

a Mode S enhanced surveillance equipage. Pricing mechanisms could therefore work to 

alleviate congestion of the 1090 MHz band. However, because of the international nature 

of aviation, there is a need first for the aeronautical community to determine a strategy for 

the long term use of ADS-B in order to ascertain detailed requirements. At that point, use 

of incentive pricing might be appropriate to encourage the most spectrum efficient 

solution. 

The final recommendation applies to extension of the use of the 1030 MHz frequency. 

Recommendation 3.20: The possibility of further utilising 1030MHz (for example, for TIS- 

B) should be encouraged and studied. 

3.4 Aeronautical Radio-Navigation Services (ARNS) 


The primary purpose of navigation is to enable an aircraft to “plan, direct, or plot its path” 

[from Collins English Dictionary] from departure to destination. 

In the early days of aviation, this would be the remit of a specialist member of the flight 

crew (navigator), whose task it was to plot the routing on a map, using visual observation 

marks. This method of navigation, known by some as ‘pilotage’, is still used in today’s 

VFR (Visual Flight Rules) flights mainly undertaken by GA aircraft. Allied to this method is 

dead reckoning: a mathematical calculation of time, distance and direction, by which a 

pilot can chart the course of his flight. Dead reckoning is still used in many forms of 

aviation as an error check. 

In today’s environment, navigation is a mix of ground-based radio navigation aids, inertial 

systems and satellite navigation systems. These provide pilots with a means to navigate 

accurately, even when in instrument meteorological conditions (i.e. IFR – Instrument 

Flight Rules). Together, these aids form the radionavigation service, the definition of 

which is: “a radiodetermination service used for the purposes of navigation, including 

obstruction warning (radiodetermination is the determination of the position, velocity 

and/or other characteristics of an object of information relating to these parameters, by 

means of the propagation properties of radio waves)”- source: ITU-R website. 

The primary purpose is still to allow aircraft to direct themselves from A to B. However, in 

today’s crowded airspace, aircraft must do this whilst respecting ATC system constraints. 

These are put in place for two main reasons: 

• To maintain or improve the safety of the flight (and overall traffic situation); 

Page 85

• To maintain or improve the orderly and efficient flow of traffic. 

These constraints mean that the route taken by civil aircraft is often not the fastest or 

most efficient one. Strenuous efforts are made in today’s environment to ensure that 

aircraft are in the air for the least time possible; passengers benefit from shorter flights 

and airlines (and the environment) benefit with less fuel being burnt. 

Unique constraints are also in place near airports; i.e. within the TMA. Aircraft must be 

able to line up with the runway from several miles away. The controller must sequence 

and merge aircraft arriving on several different routes onto one approach path. As the 

aircraft comes near the ground, noise and environment constraints must be taken into 

account. 

As the traffic grows, the constraints must become tighter – i.e. navigational performance 

must increase. It has moved from 2D to 3D, and is likely to move to 4D (i.e. with time) in 

the near future. Accuracy of navigation is continually increasing, and the availability of 

navigation aids (or GNSS) will also grow in the future. 

3.4.2 Frequency Allocations 

3.4.2.1 Scope 

This section illustrates the current frequency usage profile for navigation systems in the 

United Kingdom of Great Britain and Northern Ireland, the State of Jersey and Eire. 

3.4.2.2 Loran-C 

The band 90-110 kHz is allocated for RNS usage (and particularly in Europe and the US 

for Loran-C). 1800-2000 kHz is allocated to the now-defunct LORAN-A, and is currently 

used primarily for amateur applications. 

Internationally, the allocation to Loran-C is driven by the USA (and likely to continue to be 

– maritime use by the US Coast Guard service). Europe is represented by the Northwest 

European Loran-C System (NELS), which includes UK coverage. 

3.4.2.3 NDB 

Internationally, 130-535 kHz is allocated for aeronautical radionavigation services. Within 

ICAO’s Region 1 (Europe), 255-526.5 kHz is allocated to NDBs, although maritime uses 

some of this band. 7 It is bounded by the LF and MF sound broadcasting bands. 

Note also that mobile aeronautical NDBs, which are mainly military, operate in the UK up 

to 979 kHz, along with MF broadcasting. 

3.4.2.4 Marker Beacons 

Short range radionavigation beacons are centred on 75 MHz (74.8-75.2 MHz). Power 

output is typically 3W or less. 

7 Note that the mobile detection equipment – Automatic Direction Finders – are able to 

receive signals in the range of 190-1800 kHz. 

Page 86

3.4.2.5 ILS 

VOR/ILS localizers are allocated frequencies within the VHF band i.e. 108-117.975MHz 

internationally (ARNS). In practice, this band is split between stand-alone VOR and 

VOR/ILS, with VOR/ILS taking 108MHz – 111.975MHz. 

328.6-335.4 MHz (ARNS) is allocated to the ILS glideslope in all three ICAO regions; 

these frequencies are paired with the VHF value of the corresponding localiser. 

3.4.2.6 VHF VOR 

108-117.975MHz is allocated world-wide for ARNS. As mentioned above, the band is 

shared between ILS and VOR, with stand-alone VOR frequencies extending from 

112.000MHz – 117.975MHz. Where VORs are co-located with ILS, frequencies between 

108-111.975MHz can be used. 

3.4.2.7 C-Band MLS 

5000-5250MHz (ARNS) is allocated internationally in the C-band. However, due to slow 

take-up of Microwave Landing Systems in Europe, currently only 5030-5090MHz is used, 

with the upper part of the band reserved for expansion. How much is reserved for ARNS 

is a matter for debate. 

3.4.2.8 L-Band DME 

960-1215 MHz (ARNS/RNSS) is allocated internationally. 

From the ITU’s Frequency Allocation Footnote 5.328 – The band 960 – 1215 MHz is 

reserved on a world-wide basis for the use and development of airborne electronic aids to 

air navigation and any directly associated ground-based facilities. 

3.4.2.9 L-Band GNSS 

All frequency allocations for RNSS are world-wide, allocated through the ITU: 

• 1164 – 1215MHz (space-Earth, space-space); 

• 1215 – 1300MHz (space-Earth, space-space); 

• 1300 – 1350MHz (Earth-space); 

• 1559 – 1626.5MHz (space-Earth, space-space). 

Note: 1610 - 1626.5 MHz is currently co-assigned with radio-determination 

(radionavigation) satellite, Mobile Satellite Services and Radio Astronomy sharing the 

frequency. GLONASS radionavigation satellite service currently uses the lower part of this 

band, but after 2005 is expected to transfer to the 1559-1610 MHz band [source: ICAO 

Doc 9718]. 

Actual usage of the frequency is defined below for the three current main candidate 

GNSS solutions – GPS, GLONASS and Galileo. Note that for certain frequencies, energy 

at the carrier frequency is minimal, with the sidelobes actually dominating the overall 

signal. 

For GPS (US Military Global Positioning System): 

• L1 Link 1, carrier frequency = 1575.42 MHz +/- 12MHz; civil frequency. 

• L2 Link 2, carrier frequency = 1227.6 MHz +/- 12MHz. (military frequency for 

Precise Positioning Service, with civil usage progressively coming on-line from 

2003 to 2008). 

• L3 Link 3, other use. 

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• L4 Link 4, carrier frequency = 1379.913 MHz; ionospheric correction. 

And in the future: 

• L5 Link 5, carrier frequency = 1176.45 MHz +/- 12MHz (operational by 2008, 

and planned for use in critical safety of life applications such as world-wide civil 

aviation – note however that there has been no decision yet taken on the use of 

this frequency within the UK). 

For GLONASS (Russian Federation military-based Global Navigation Satellite System): 

• L1 = 1598.0625 – 1605.375MHz +/- 5.11MHz. Note that 1610.485 – 1614.4225 

MHz is currently assigned to GLONASS L1, but will be re-allocated by 2005. 

• L2 = 1242.9375 – 1248.625MHz +/- 5.11MHz. Note that 1253.735 – 1256.7975 

MHz is currently assigned to GLONASS L2, but is due to be re-allocated by 

2005. 

For Galileo (European GNSS): 

• E1: 1587-1591MHz and E2 – 1559-1563MHz – these are also commonly 

referred to as E2-L1-E1, as they are co-located with the L1 GPS signal. 

• E4: 1254-1258MHz. 

• E5: Galileo carrier frequency = 1198 MHz (planned for operation by 2008-2010) 

with significant sidelobes up to +/- 10MHz (in effect, there are two separate 

carrier frequencies – E5a and E5b – at 1176.45MHz and 1202.025MHz 

respectively). Note that the allocation given by WRC2000 is 1164-1215MHz. 

• E6: Galileo carrier frequency = 1278.75MHz +/- 10MHz. (WRC2000 allocation of 

1260-1300MHz). 

• C1 – Galileo = 5010-5030MHz. 

There is also an Earth-space allocation from 1300-1350MHz for RNSS earth stations. 

1164 MHz 

E5a/E5b E6 L1 

L5 

space - Earth, 

space - space 

1188 MHz 

1215 MHz 

L2 G2 L1 G1 

space - Earth, space - space 

1260 MHz 

E4 L4 L3 

1300 MHz 

1559 MHz 

E2 

Earth - space 

space - Earth, 

space - space 

E1 

1626.5 MHz 

5010 MHz 

C1 

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5030 MHz

3.4.3 Technology Descriptions 

EN-ROUTE NAVIGATION AIDS 

Figure 3-14 – RNSS allocations 

3.4.3.1 Loran-C 

Loran-C (Long Range Navigation) is a low frequency, hyperbolic, terrestrial 

radionavigation aid. It is approved as a supplemental air navigation system for IFR and 

VFR use – low predictable accuracies mean that it cannot be used as a primary system. 

Organisation and pulse structure 

Loran-C transmitters are organised into chains of 3 to 5 stations. Within a chain, one 

station is designated a ‘master’ station, and the others are ‘secondary’ stations. The 

Loran-C chains are used to provide the user with 2-dimensional position, velocity and, in 

some cases, time. The technical parameters and operation of Loran-C are wellunderstood 

as it has been operational since the late 1950s. 

The Loran-C navigation signal is a structured sequence of short radio frequency pulses 

on a carrier wave centred at 100 kHz. These pulses are transmitted in groups of eight or 

nine pulses forming a ‘burst’. All secondary stations radiate pulses in groups of eight, 

whereas the master signal has an additional ninth pulse to enable identification (Figure 

3-15). 

The sequence of signal transmissions consists of a pulse group from the master station 

(M) followed at precise time intervals by pulse groups from the secondary stations (W, X 

W, X, Y, and Z in Figure 3-15). The time interval between the re-occurrence of the master 

pulse is called the Group Repetition Interval (GRI). Each Loran-C chain has a unique 

GRI, allowing each receiver to identify and isolate signal groups even though all Loran-C 

transmitters operate on the same frequency. 

The geographical line between the master and each secondary station is called the 

baseline. Typical baselines range from 1200 to 1900 km. Chain coverage is determined 

by the power transmitted from each transmitter in the chain, the distance between them 

and how the different transmitters are oriented in relation to each other (the geometry of 

the chain). 

M W X Y Z M 

GRI 

Figure 3-15 – Loran-C pulse structure 

Time 

The figure above shows the pulses against a time baseline, with the Master station (M) 

and 4 secondary stations (W, X, Y and Z). The ninth pulse, identifying the Master station, 

can be seen in the diagram. 

Receiver operation 

A basic Loran-C receiver measures the time difference (TD) between the time-of-arrival of 

the master signal and the signals from each of the secondary stations of a chain. Using 

these TDs, plus the velocity of radio propagation, and allowing for the curvature of the 

earth, a line-of-position (LOP) is computed for each pair of stations. 

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The intersection of each line-of-position provides the geographic position of the receiver. 

Each line-of-position is the shape of a hyperbola, classifying Loran-C as a hyperbolic 

system. 

An alternative mode of receiver operation uses only two transmitting stations and an 

accurate atomic clock at the receiver to provide actual time of arrival of the transmitted 

signals (ranging). This mode is called Rho-Rho navigation. In this mode the lines of 

position are circular, and the intersection of the circles gives the geographic position. The 

two-position ambiguity of intersecting circles may be removed by other means. Use of this 

mode of operation is restricted owing to the high cost of receiving equipment. 

Additional secondary factors (ASFs) 

Loran-C receivers compute distances from Loran-C transmitting stations using time of 

arrival measurements and the propagation velocity of the radio ground wave to determine 

position. Small variations in the velocity of propagation between that over sea water and 

that over different land masses are known as the Additional Secondary Factors (ASFs). 

Corrections may be applied to compensate for such variations. The corrections improve 

the accuracy of the Loran-C service at locations where the received Loran-C signal 

passes over land on its way from transmitter to receiver. 

The values of ASF depend on the conductivity of the earth’s surface along the signal 

paths. Sea water has high conductivity, and the ASFs of sea water are by definition zero. 

Dry land, mountains, or ice generally have low conductivity and radio signals travel over 

them more slowly, giving rise to substantial ASF delays and hence degradation of 

absolute accuracy. 

ASFs vary little with time, and it is therefore possible to calibrate the Loran-C service by 

measuring ASF values throughout the coverage area. NELS currently have a programme 

for the mapping of the ASFs in northern Europe, based on a combination of computer 

modelling and field measurements. When the data has been collected, it is intended that 

these corrections will be available as electronic databases for incorporation in Loran-C 

receivers. 

Propagation anomalies 

The Loran-C system is suitable for many land radio location applications. However, 

propagation anomalies may be encountered in urban areas caused by the proximity of 

large man-made structures. 

Compensation for these anomalies is usually possible either by prior measurement or by 

the application of the local ASFs. However, improvement in the accuracy of Loran-C 

service may also be achieved by the measurement and broadcast of local corrections if 

required. 

Service provision in Europe – Northwest European Loran-C System (NELS) 

The principal Loran-C activities in Europe are co-ordinated through the Northwest 

European Loran-C Agreement, which established the Northwest European Loran-C 

System (NELS). 

NELS is currently providing a Loran-C service from 8 transmitter stations in Norway, 

Denmark, Germany, and France. A map showing the current Loran-C coverage as 

predicted by NELS is shown in Figure 3-16. NELS has predicted the additional coverage 

that will be obtained when the Loophead station in Ireland becomes operational – shown 

by a dotted red line in the figure below. The commissioning of this station is pending the 

resolution of disagreements on planning permission and legal issues. 

Page 90

Figure 3-16 – Current (and future – dotted red line) Loran-C coverage as predicted 

by NELS 

3.4.3.2 NDB 

Non-directional beacons have been used as a primary airborne navigation aid since 

World War II. Non-directional signals are transmitted via a low or medium frequency, 

whereby a properly equipped receiver can determine bearings and ‘home in’ on the 

station. Alternatively, the opposite radial can be used to track away from the beacon. 

The radio signal is broadcast in every direction at once; hence its name, non-directional 

beacon. Ranges can vary from a few miles to hundreds of miles, depending on the 

antenna power. The NDB station consists of a radio transmitter, an antenna coupling 

device, and an antenna. NDBs are allocated frequencies by the ITU from 130 – 535 kHz, 

with Europe (ICAO Region 1) actually using a narrower band between 255-526.5 kHz. 

Mobile aeronautical off-route NDBs (used by the military) are assigned frequencies up to 

979 kHz in the UK. Channelisation is 1 kHz. 

NDBs are omnidirectional. Transmission power depends on the role of the beacon – 

short-range locators may transmit at 10W, whereas en-route beacons can transmit at 

powers up to 1kW. Typical aviation NDBs transmit at between 25 and 200W. 

In order to track a signal, the aircraft must be fitted with an Automatic Direction Finder 

(ADF). The ADF set is used in an aircraft, and consists of a receiver that will pick up a 

radio signal in the 190 kHz to 1800 kHz radio band. The ADF receiver utilizes two 

antennas to intercept the radio signal and determine the direction of that signal. This 

directional information is displayed on an instrument that points to a compass heading 

indicating the direction from the receiver to the source of the radio signal. No distance 

measurements are included. 

3.4.3.3 VHF VOR 

One of the reasons for the unreliability and inaccuracy of airborne direction finding 

systems operating with ground medium frequency beacons (NDBs) and public broadcast 

stations is that medium frequencies (i.e. longer wavelengths) can be badly affected by 

atmospheric interference, skywave interference and coastline refraction. VOR (VHF 

Omni-Range) uses frequencies that are high enough to avoid these problems as their 

primary signal propagation is by space waves (or line-of-sight). 

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VOR beacons transmit in the 108 – 117.975 MHz band using two antennas (one omnidirectional 

and one loop) to generate a polar diagram called a Limacon. In conventional 

beacons, the loop aerial is then mechanically rotated at 30 Hz so that the polar diagram 

rotates. An aircraft, receives this signal which varies in amplitude at 30 Hz and represents 

the aircraft’s bearing from the beacon; however, to decode the bearing, a reference is 

required and this is transmitted by the beacon as a fixed 30 Hz Frequency Modulated 

signal (it actually uses a sub-carrier at 480 Hz from the primary frequency to avoid 

interference with the AM modulations received at the aircraft). As shown below, the 

reference signal is calibrated such that the two 30 Hz signals (one AM and one FM) are 

identical for an aircraft on a bearing of magnetic North from the beacon [see Figure 3-17 

– top]. Elsewhere, the measured phase difference (θ) between the AM and FM signals 

represent the magnetic bearing of the aircraft from the beacon [see Figure 3-17 – 

bottom]. 

VOR Beacon 

Limacon A 

North (M) 

θ 

Θ = Phase Difference measured 

at the aircraft 

Figure 3-17 – Operation of a VOR System 

Even if there is some minor misalignment at the beacon, aircraft on the same bearing 

from the beacon will receive the same information; this was not necessarily the case 

using the DF/NDB bearing system, which usually suffered from different direction finding 

errors even with two receivers in the same aircraft. Other advantages over NDB bearing 

systems are that the VOR receiver is relatively simple needing only to demodulate the FM 

signal and compare its phase with that of the AM signal; no moving parts are involved and 

B 

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only a standard omni-directional VHF aerial is required; the beacon’s audio sub-carrier 

can also be used to transmit information such as the weather conditions at local airfields. 

Although VOR is a line-of-sight system, VOR beacons are given a protected range to 

prevent problems of mutual interference with other beacons. Clearly, because the VOR 

system is passive (i.e. the aircraft does not transmit), there is no limit to the number of 

users of VOR bearing information. 

The bearings received from conventional VOR beacons are still susceptible to some 

errors mainly through multi-path reflections usually termed “siting errors”. One solution is 

to use a different design of beacon known as Doppler VOR. In these beacons, the 

rotating loop is replaced by 50 aerials placed on the diameter of about 14 metres. 

Transmissions are made sequentially as phase differences so that the Limacon is 

reproduced but as a FM signal, and the omni-aerial now transmits an AM reference. The 

aircraft receiver cannot tell the difference between conventional and Doppler VOR 

beacons and merely compares the two signals as before to produce a bearing. The main 

advantages of the DVOR are the large aperture of the aerial which reduces multi-path 

effects and the elimination of moving parts giving a higher reliability of the ground beacon. 

Typically (with a conventional beacon) the ground beacon will be in error by ± 3° through 

multi-path and calibration, and the aircraft receiver contributes another ± 3° through the 

inaccuracy of phase difference measurements; this gives a 95% error value of ± 4° for 

bearings at the output of the receiver. While this is satisfactory for using to home 

overhead a ground beacon, bearing errors of this magnitude are not very satisfactory for 

position fixing as the across bearing distance errors increase with increasing range from 

the beacon. 

VORs use a 50 kHz channelisation. VORs based on an airport (used for short-range 

application) tend to use powers in the range of 25-50W; for en-route VORs, this value 

increases to 100-200W. 


DME (Distance Measuring Equipment) is a system whereby paired pulses at specific 

frequencies are sent out from the aircraft (i.e. an airborne interrogator) and received at 

the ground station, which then transmits paired pulses back to the aircraft at the same 

spacing, but on a different frequency (offset by 63 MHz). The time for the round trip is 

measured by the airborne DME unit, and calculated as distance. Only slant range is 

displayed, meaning that DME suffers from limitations at short ranges (i.e. when the 

aircraft is directly overhead, as slant distance becomes equal to altitude). The pulse 

repetition rate (unique to each aircraft) varies from 5-150 per second, allowing up to 100 

aircraft to be handled by one DME station. 

The Distance Measuring Equipment (DME) developed for military purposes as part of 

TACAN was still classified equipment in the late 1940s, and was not made available to 

civilian users until the 1950s. 

DME operates in the 960 – 1215 MHz band, which means that, like VOR, DME is a lineof-sight 

system. DME is an active system; i.e. the aircraft has to transmit to obtain 

information. The transmission (or interrogation as it is called) consists of a pair of pulses. 

On receipt of such a pulse-pair exceeding a preset amplitude, the beacon responds after 

a pre-set delay with an equivalent pulse-pair. In fact, for transmitter efficiency, the ground 

beacon transmits continuously producing pulse-pairs mainly as random noise. As more 

aircraft interrogate the beacon, its receiver gain is reduced until about 100 aircraft 

responses are handled and the beacon is producing replies and no noise; this places a 

practical limit on the number of aircraft that can use the beacon. 

The aircraft receives its replies amongst many other pulse-pairs (noise and replies to 

other aircraft). The aircraft receiver recognises its own replies by integrating over a 

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number of interrogations that are made at irregular intervals (prf jitter) and locks onto 

those replies that consistently arrive at a regular time (i.e. at the same range). In search 

mode, the aircraft interrogates at about 150 pulse-pairs per second, but this rate is 

dropped to 24 – 30 once lock-on is achieved. Using a value for the speed of 

electromagnetic wave propagation in air, the time interval between interrogation and 

reception can be converted into distance (allowing for the beacon delay) which in the 

case of aircraft is of course slant range. 

Slant Range = ½ (time - delay) x speed of propagation 

Slant Range 

Interrogation pulse-pairs 

Beacon replies 

(after a fixed delay) 

DME 

Beacon 

Figure 3-18 – Operation of a DME system 

Typical accuracy (95%) of DME is 0.1nm or 0.2% of range; however, this relies on 

calibration of the ground beacon delay. Aircraft receivers take account of this delay, but if 

the ground beacon is out of calibration, errors will occur. 

As the system started as a military design, the frequency band used is divided into 252 

Channel numbers, with 1 MHz channelisation. These channel numbers are paired with 

VOR, MLS and/or ILS frequencies. 

The airborne and ground systems use effective radiated powers between 30-50dBW. 


Satellite navigation is used to determine position, velocity and precise time by receiving 

signals transmitted from several satellites in a constellation. Navigation receivers 

measure the distance from the receiver to the satellite using a technique known as 

‘passive ranging’ – 3 satellites in range allow a determination of 2D position, 4 satellites 

allow a 3D position with a precise time measurement. 

Three potential GNSS providers exist – the United States’ Global Positioning System 

(GPS), the Russian Federation’s Global Navigation Satellite System (GLONASS), and 

Europe’s future deployment of Galileo 8 . 

GPS currently uses 4 bands, with each providing specific functions. L1 and L4 are used 

for general positioning functions; L2 is used for the precise position determination (mainly 

military, but in the future it will be opened up for civil usage); L3 has other uses. The US 

government has a policy to encourage access to these frequencies – as such, L1 and L2 

will be increased in power, and selective availability (only allowing coarse position) has 

8 

Note that a Chinese system may become operational in the future, but no firm details or 

timescales are yet available. 

Page 94

een switched off. L1 and L2 are therefore both currently used for precise position 

determination. 

The ITU has recently allocated two extra frequencies to GPS and Galileo; the L5 and E5 

frequency bands both fall within the L-band currently allocated to ARNS (in particular, 

DME). Note that this is also applicable to the future allocation for Galileo E6. 

Power flux density limits are placed on GNSS, to protect the current ARNS applications 

(i.e. in the E5, E6 and L2/G2 bands): WRC-03 placed an aggregate EPFD of - 

121.5dBW/m 2 /MHz on all RNSS systems in the band 1164 – 1215 MHz. 

To ensure sufficient availability, accuracy and integrity for critical aviation applications, 

GNSS is supplemented by augmentation systems – these can be wide area (WAAS), 

regional area (RAAS), or local area (LAAS). 

Wide area augmentation systems tend to be space-based, to provide the greatest 

possible coverage. In Europe, EGNOS is being developed to provide the space-based 

augmentation service from 2005. Whether this will support safety-of-life applications (such 

as civil aviation) has yet to be determined (through the production of the safety case). 

EGNOS (geostationary satellites supported by ground stations) will operate over the 

same frequencies as GNSS (L1, L5 and E5 being in current plans). Similar systems exist 

in the USA (WAAS), Japan (MSAS) and China (SNAS). 

Local area augmentation systems are ground-based, and are commonly known as GBAS 

(Ground-Based Augmentation Systems). These consist of data transmissions of 

navigation information from ground stations. They operate over the VHF frequencies 

(108-117.975MHz) with 25 kHz channel spacing, and therefore compete with ILS and 

VOR for spectrum allocation. 

AIRPORT-ONLY NAVIGATION AIDS 

3.4.3.6 ILS 

The ILS is an approach system that provides horizontal and vertical guidance, and 

distance information. ILS consists of transmitter stations on the ground and receivers onboard. 

Technical Characteristics 

The system is composed of several subsystems: 

VOR/ILS Localizer: is used to provide lateral guidance to the aircraft and thus allows for 

tracking the extended runway centreline. The localizer information is typically displayed 

on a course deviation indicator (CDI) which is used by the pilot until visual contact is 

made and the landing completed. The localizer radiates on a carrier frequency between 

108 to 112 MHz with 50 kHz channel spacing. This carrier is modulated with audio tones 

of 90 Hz, 150 Hz, and 1020 Hz. The 1020 Hz tone is used for facility identification. 

Sectorised antennae are used to ensure the primary strength of the signal is aligned with 

the runway centre-line (within 10 degrees of the on-track signal, the reception range is 

approximately 18nm). The effective radiated power is approximately 50W. 

ILS Glide slope: provides the pilot with vertical guidance. This signal gives the pilot 

information on the horizontal needle of the CDI to allow the aircraft to descend at the 

proper angle to the runway touchdown point. The glide slope radiates on a carrier 

frequency between 329 and 335 MHz and is also modulated with 90 Hz and 150 Hz 

tones. The glide slope frequencies are frequency paired with the localizer, meaning the 

pilot has to tune only one receiver control. The glide slope is normally between 2.5 and 3 

degrees so that it intersects the middle marker at an altitude of about 200 ft and the outer 

Page 95

marker at an altitude of roughly 1400 ft (above runway elevation). Sectorised antennas 

are used, with powers roughly similar to airport VORs (i.e. 50W). 

Marker beacons: are used to alert the pilot that an action (e.g., altitude check) is needed. 

This information is presented to the pilot by audio and visual cues. The ILS may contain 

three marker beacons: inner, middle and outer. The inner marker is used only for 

Category II operations. The marker beacons are located at specified intervals along the 

ILS approach and are identified by discrete audio and visual characteristics. All marker 

beacons operate on a frequency of 75 MHz (OM: 400 Hz, MM: 1300 Hz, IM: 3000 Hz). 

The beams radiate vertically with a diameter of approximately 3500ft at a height of 1000ft 

(evidently, the value increases as the altitude increases). Power is usually 3W or less 

(although note that the Outer Marker may be replaced by an NDB, which uses a power of 

around 25W). 

Distance Measuring Equipment (DME) is increasingly co-located with ILS to replace the 

marker beacons. 

ILS suffers from Course Distortion. This is disturbances to localiser and glide slope 

courses when surface vehicles (e.g. aircraft that taxi) operate near the localiser or glide 

slope antennas. Areas where this occurs are called ILS Critical Areas. It is the Air Traffic 

Controller’s responsibility to ensure that no interference exists when ILS approaches are 

in progress. 

Operational Aspects 

The visibility conditions at the airport have an impact on the approach and landing phase 

of a flight; that is the main reason why for landing operations, visibility conditions on the 

runway have been classified into several categories namely NPA, NPV, CAT I, CAT II and 

CAT III. 

• Non-precision approach operations basic (NPA). An instrument approach 

which does not rely on the utilisation of vertical guidance relative to a glide path. 

• Non-precision approach operations with vertical guidance (NPV). An 

instrument approach which utilises guidance relative to a glide path and does not 

meet requirements established for precision approach and landing operations. 

• Precision approach and landing operations (PA). An instrument approach 

and landing using precision lateral and vertical guidance relative to a glide path 

with minima as determined by category of operation. Precision approach is 

classified into three operational categories. 

The three groups are defined in terms of the Runway Visual Range (RVR) and Decision 

Height. The Decision Height is the lowest height above the runway where pilots make the 

decision to continue the landing or to abort. It is based on the ability of pilots to obtain 

guidance from visual cues on the ground rather than from instruments in the cockpit. If 

pilots are unable to see a sufficient number of visual cues at the decision height, the 

landing must be aborted. 

The International Civil Aviation Organisation (ICAO) defines three categories of visibility 

for landing civil aircraft with the aid of an Instrument Landing System: 

Category I: The decision height (height at which the pilot must have established visual 

contact with the runway) is not lower than 200 ft. If the runway is not clearly visible to the 

pilot at the Decision Height, then a Missed Approach must be executed. The Runway 

Visual Range is not less than 1800 ft (using some kind of runway lighting). The RVR is 

measured on the ground and communicated to the Pilot by ATC. 

Category II: The decision height is not lower than 100 ft. The Runway Visual Range is 

not less than 700 ft. The aircraft must carry a dual ILS receiver to perform a CAT II 

Page 96

landing. He must carry either a radar altimeter or inner-marker receiver to measure the 

decision height. He must also have an autopilot, and two pilots. 

For Category I and II operations, two transmissometer measurements are made, one 

made near the threshold and the other about midway down the length of the runway 

(transmissometers measure the transmission of light through a medium – in this case, 

providing information on the medium, since light’s characteristics are well-known). The 

latter location provides useful information for aircraft taking off as well as for landing 

aircraft during landing roll. The limitation of the transmissometer is that it measures 

visibility on the ground, whereas pilots approaching a runway like to know the visibility on 

the approach path. 

Category III: This category is further subdivided in three classes: 

• CAT IIIa: The decision height is lower than 100 ft and the RVR is not less than 

700 ft. 

• CAT IIIb: The decision height is lower than 50 ft and the RVR is not less than 

150 ft. 

• CAT IIIc: Zero visibility 

These sub-categories can also be expressed as aircraft capabilities – for Category IIIa 

operations, an automatic landing capability, i.e. the aircraft touching down on the runway, 

is required. For Category IIIb operations, an automatic rollout capability in addition to an 

automatic landing capability is required. For Category IIIc operations, the taxiing portion of 

the landing must also be automatic. 


Concept 

The Microwave Landing System (MLS) originated in the early 1970’s. The MLS is a 

precision approach and landing guidance system which provides two or three dimensional 

position information and various ground to air data. International standardisation for the 

MLS Time Reference Scanning Beam (TRSB) concept was reached by the International 

Civil Aviation Organization (ICAO) in 1978. 

The main components of MLS are: 

• Elevation Subsystem; 

• Azimuth Subsystem; 

• Back Azimuth Subsystem; 

• DME/P. 

Technical Characteristics 

The MLS duplicates and augments the capabilities of the ILS, which provides a ± 0.7º 

proportional guidance region around the glide slope angle and a region of approximately 

± 3.0° azimuth about the centreline approach of the instrumented runway. The MLS is 

capable of providing a maximum ± 62.0° azimuth coverage region with a typical 

installation using only ± 40.0° azimuth coverage region. The MLS elevation signal can 

provide coverage up to +30.0° above ground level. The glidepath can be varied from 0.1 

to 15°. This could allow helicopters to use an appropriate glidepath. 

Two of the transmitters provide MLS azimuth functions; they are located at each end of 

the runway, and are positioned facing the runway. With both runway directions equipped, 

the azimuth antenna facing the approaching aircraft is configured as the approach 

azimuth transmitter and the opposite antenna becomes the back azimuth transmitter. The 

approach azimuth transmitter is used to guide the aircraft during an instrument (non- 

Page 97

visual) approach to the active runway. It may also be used in precision area navigation 

(RNAV) when coupled with the elevation and distance measuring equipment that are the 

remaining transmitted signals. 

The Azimuth and Back Azimuth signal beam shapes are both fan-shaped in a vertical 

plane formed along any of the antenna’s radials. As viewed by the pilot of an aircraft on 

final approach to the runway, the azimuth beam is swept from the right-most coverage 

angle to the left-most in the “To” scan, and is then returned from the left to right coverage 

angle in the “From” scan after a specified delay at the left-most limit. The time difference 

between the reception of the two scans is determined. A third signal transmitted is the 

elevation signal. This fan-shaped beam is transmitted from the Elevation antenna located 

abeam the MLS datum point. The beam originates at an angle near horizontal (minimum 

elevation angle), scans to the upper elevation angle limit in an upward direction (the “To” 

scan), and then returns (the “From” scan). The time interval between the “To” and “From” 

scans is measured in the receiver and based on the data transmitted from the ground 

(concerning site geometry and configuration) the elevation angle of the aircraft is 

determined. 

The MLS system has 200 channels, with a 1MHz channel spacing (ILS has only 40 

channels). Technically, this allows for a nearly unlimited number of MLS installations 

without interference. However, low operational need means that not all of the available 

channels are currently required. 


3.4.4.1 General navigation requirements 

Introduction to RNAV and RNP 

RNAV (or Area Navigation) is a method which permits aircraft operation on any desired 

flight path within the coverage of referenced navigation aids, or within the limits of the 

capabilities of self-contained aids (i.e. IRS/INS), or both. The Required Navigation 

Performance (RNP) determines the accuracy of the RNAV system to determine the 

aircraft’s absolute geographical position (instead of its position relative to a navigation aid, 

as is the case with VOR/DME etc). 

The RNP for aircraft in the ECAC area is mandated to RNP 5 (i.e. the containment value 

is 5nm) – also known as B-RNAV (Basic area navigation). States must ensure that the 

navigational infrastructure provided adequately supports the prescribed RNP type in a 

specific area (or on a specific route). 

RNAV represents a fundamental change in navigation philosophy. Instead of flying 

to/from specific navaids, aircraft can now determine their absolute position from a variety 

of inputs (e.g. VOR, DME, GNSS and INS). As such, the coverage of these navaids 

should be tailored to ensure that at all times the aircraft can determine its position to 

within 5nm (or whatever the RNP value is set to). Note that not all navaids are required – 

whatever is provided must be sufficient to provide the required performance (and possibly 

include a redundant system due to the criticality of the application). As a result of this 

concept, the practice of ‘point-to-point’ navigation is becoming rare in civil aviation. 

In order to facilitate this move to RNAV, many aircraft are equipped with Multi-Mode 

Receivers, or MMR, which integrate L-band, VHF, UHF and C-band signals in the flight 

management system. 

EN-ROUTE NAVIGATION AID REQUIREMENTS 

Page 98

3.4.4.2 Loran-C 

Loran-C is promoted as a possible back-up to satellite-based navigation means (i.e. 

GNSS), along with triple INS/IRS 9 , VOR/DME and GBAS. In practice, modern aviation is 

likely to choose the alternatives for GNSS back-up due to Loran-C’s limited coverage in 

Europe, and the low predictable accuracies returned by the system. 

Maritime continues to use Loran-C as a primary means of navigation. ICAO believe 

several States’ GA communities have equipped with Loran-C airborne receivers; as such, 

they foresee an operational need in the medium term. 

3.4.4.3 NDB 

In modern aviation, NDBs are used primarily in instrument approaches. Often co-located 

with the Outer Marker (referred to as a Locator Outer Marker, or LOM), they can be used 

in precision or non-precision approaches. 

Within the UK, several NDBs are used as small airport locators (i.e. essential for General 

Aviation navigation). This also applies to offshore operations in the UK - navigation to 

oilrigs is currently exclusively by means of NDBs. As GPS operations become 

commonplace, NDBs will be used as a redundancy check. 

Where NDBs are used as part of an instrument approach, and no equivalent groundbased 

means exist for transition to the ILS course (e.g. DME), it can be expected that 

these shall be maintained until the ILS system is no longer used (thought to be in the very 

long term – e.g. 2015) . Evidently, replacement of the NDB’s role in an ILS approach 

procedure (for example, by the installation of a DME or VOR) would also enable the 

decommissioning of further NDBs. Stand-alone NDBs, used in en-route airspace or as 

locators for smaller airports, may be phased out earlier. 

The UK Ministry of Defence also uses mobile aeronautical NDBs for off-route operations; 

these are co-allocated with medium frequency broadcasting in the UK. Future military 

requirements for these beacons are not known, and will depend on the military’s 

upgrading to GNSS-based navigation solutions. 

3.4.4.4 VHF VOR 

VORs have been core in Europe’s navigation plan since their introduction, providing the 

ability to fly to/from a beacon accurately. As mentioned above, this has recently changed 

with the advent of RNAV procedures. Beacons are no longer a prerequisite along routes – 

instead, coverage of suitable navigation aids must be available to allow an aircraft to 

determine its position. 

GNSS is expected to fulfil the primary role of position determination. However, due to 

safety and security requirements, GNSS is expected to require a redundant ground-based 

navigation system; VOR systems being one of the candidate solutions (with DME/DME, 

triple inertial etc). 

The pressures on the VHF band, along with the relative accuracy of a DME solution 

compared to VORs, mean that EUROCONTROL favours a DME/DME solution for 

redundancy (and safety/security) requirements. As such, rationalisation of the VOR 

infrastructure is likely to take place for en-route operations within the next 5 years – 

EUROCONTROL plans to withdraw VORs in ECAC airspace by 2010. 

9 INS/IRS – Inertial Navigation (or Reference) System – an inertial system that measures 

changes in acceleration and rotation to determine position, attitude and velocity. 

Generally, three independent systems are installed in modern civil aircraft for redundancy. 

Page 99

Some military GAT operations may still require conventional infrastructure support 

beyond the 2010 limit foreseen by EUROCONTROL for the phasing out of VORs. 

The UK is likely to make a decision regarding the future deployment of VORs in the near 

future – it is recognised by the CAA that there may be redundancy in the current system, 

with VOR/DME providing the same function and GNSS coming on-line. 


DME, as part of RNAV operations, is likely to be the primary means of navigation in the 

short term. After 2006 (EGNOS introduction), they are likely to be used as the main 

secondary navigation aid (providing redundancy for GNSS). No decommissioning is 

therefore planned in Europe. Indeed, on the contrary, comprehensive coverage of DMEs 

shall be required in ECAC airspace by 2005 and in TMAs by 2010. 

The MoD liaises with the UK CAA in the provision of military DME/TACAN allocated for 

primary usage. The MoD indicated that they would not want to rely solely on a spacebased 

navigation solution (for security and safety reasons) – DME/TACAN systems are 

therefore likely to play a significant role in the future. 


GNSS offers the potential to provide one system for all phases of flight, thus reducing the 

amount of equipment carried on-board an aircraft (and the cost). GNSS is forecast to 

become a ‘sole means’ of navigational positional determination in the long term (circa 

2020). It is therefore a critical safety-of-life issue to protect the allocation of the spectrum 

GNSS has been given (5 bands for GPS, 6 for Galileo). 

Within Europe, overall space-based augmentation for GPS, GLONASS and subsequently 

Galileo is planned to be provided by EGNOS (European Geostationary Navigation 

Overlay System) circa 2006. More accurate timings, accuracies and integrities will be 

available to the user. Other systems world-wide will provide a similar service (e.g. 

WAAS). At a European level, the funds have been committed to develop EGNOS to pass 

an operational readiness review (ORR) – following this, the safety case will need to be 

developed before safety-of-life applications may be carried out using the system. The UK 

is yet to make a firm decision on the use of EGNOS. 

Augmentation may be necessary for specific phases of flight – for example, nonaugmented 

GNSS height information does not meet accuracy requirements for precision 

approaches. This should be provided by GBAS in the near-term, with a European 

roadmap for GBAS development and implementation being prepared by EUROCONTROL. 

The implementation of GBAS may allow precision approaches; work is on-going to 

determine the possibility of a GNSS Landing System capable of Category II or III (current 

systems, allied to GBAS, should be capable of Category I – Galileo when implemented 

will also meet Category I requirements). 

AIRPORT-ONLY NAVIGATION AID REQUIREMENTS 

3.4.4.7 ILS 

VOR/ILS localizers are standard for instrument approaches in Europe (and world-wide). 

Although only short-medium range, frequency allocation problems are increasing in core 

areas due to the operational requirement to frequency pair with DME/MLS. 

Traditionally, marker beacons have been used in the design of instrument approaches, for 

pilot awareness on the approach. However, they are now being replaced by DMEs, which 

provide a much greater operational benefit. 

Page 100

Recent studies in the USA have indicated that the middle marker has no discernible 

benefit; there is also a recommendation to replace the outer marker with a navaid 

(VOR/DME) to facilitate procedure design. 


Although carrying out a similar function to ILS equipment, MLS provides better 

performance in fog or low cloud, and is immune to multi-path effects from local buildings 

or aircraft. It also allows curved approaches (e.g. that are necessary due to terrain). 

The future of MLS is unsure. In 1974 ICAO solicited proposals for the replacement of ILS. 

The Time-Reference Scanning Beam MLS, proposed by Australia and the US, was 

recommended by ICAO in 1978. The MLS standard was adopted in 1985 and it was 

planned to migrate from ILS to MLS in 1998. When Satellite Navigation Systems became 

available it was believed that MLS would be abandoned. Support for MLS is stronger in 

Europe than it is in the US. In fact, the 2001 Federal Radionavigation Plan (FRP) states: 

“The FAA has terminated the development of the Microwave Landing System (MLS) 

based on favourable GPS test results. The U.S. does not anticipate installing additional 

MLS equipment in the NAS (National Airspace System).” 

Europe currently believes that SBAS and GBAS will not provide the necessary 

augmented accuracies to GNSS to allow precision approaches greater than Category I by 

2010. MLS is therefore still being implemented across Europe. 

NATS ordered four MLS to be installed at London Heathrow. The Airbus’ ordered by 

British Airways will be equipped with MLS receivers. NATS has also placed options for 

additional MLS installations at other airports across the country. The UK MoD has 

expressed a strong operational need for the use of MLS on mobile runways. It is 

understood that up to 50 systems may have been ordered. 

The safety aspects of MLS may eventually lead to a more structured implementation 

(including a possible mandate). For the moment, the decision is one of safety and 

economics (as it allows greater capacity at airports in non-optimum weather conditions). 

Operational need will also depend on the evolution of GNSS Landing Systems, which 

cannot currently be predicted accurately. 

3.4.4.9 Summary 

The table below shows a summary of the operational requirements for each navigation 

means, and how they impact on spectrum use and efficiency (i.e. opportunities for 

spectrum efficiency gains, and constraints on that gain). 

Page 101

Navaid Development Impact on Spectrum Comment 

En-route 

Loran-C 

NDB 

VOR 

DME 

Support for Loran is 

decreasing – the EC or 

EUROCONTROL are 

not likely to support 

Loran in their plans. It 

may therefore become 

redundant as EGNOS 

and Galileo are 

introduced. 

Withdrawal of NDB in 

Europe by 2010 as 

part of move to RNAV 

operations. 

Rationalisation in the 

near-term. Redundant 

system as far as 

commercial aviation is 

concerned. 

Advent of GNSS and 

direct routing will lead 

to decommissioning of 

VOR infrastructure in 

the long term. 

Operational 

requirements on DME 

increase due to greater 

traffic density and 

European reliance on 

DME/DME 

infrastructure. 

From an aviation 

perspective, the 

spectrum could be 

freed for other 

applications. 

However, aviation is 

not the sole users of 

Loran. 

An opportunity to 

allow secondary uses 

(on a non-interfering 

basis) during the 

transition. 

Once region is NDBfree, 

the spectrum 

could be re-used for 

other applications 

(locally in UK / Europe 

initially – other ICAO 

regions may not be so 

quick to 

decommission NDBs). 

Possible alternative 

uses in-band in the 

long term with 

secondary use in the 

short term. (see also 

discussion on same 

subject in Section 5). 

Greater congestion in 

960-1215 MHz band. 

NELS has 

development plans 

through to 2020. 

Although aviation’s 

requirements on 

Loran are very low, 

there are other users, 

for example maritime, 

who continue to 

promote the system. 

Introduction of Eurofix 

may mean Loran is 

used as GNSS 

augmentation in the 

short->medium term. 

GA still has use in UK 

(particularly when 

used as airport 

locators), as does 

offshore operations. 

The freeing of the 

NDB spectrum 

depends on: 

a)how powerful the 

GA lobby will be; 

b) how quickly GA will 

move to a GNSSbased 

solution. 

Also, even if only GA 

uses NDBs, they will 

still constitute a 

‘safety-of-life’ 

application, and 

require the requisite 

protection from inband 

or out-of-band 

interference. 

Again, GA’s speed of 

transition to GNSS will 

determine how fast 

these 

decommissioning 

plans will be 

implemented. 

EUROCONTROL 

supports a DME/DME 

infrastructure as 

backup to GNSS. 

Greater coverage 

therefore required – 

approx 230 extra 

stations are expected 

to be implemented. 

Page 102

Airport 

GNSS 

Marker 

Beacon 

ILS 

MLS 

Operational benefits as 

a single system for all 

phases of flight. 

Recent studies show 

that marker beacons 

are becoming 

redundant. Co-located 

DME is by far the 

better solution. 

ILS is a standardised 

fully deployed system. 

May be a move to MLS 

on the basis of safety 

or operational need at 

high capacity airports. 

Slow take-up of MLS 

may free up spectrum 

for other uses (GNS, 

AMSS) locally. 

Critical to protect 

GNSS spectrum 

allocations, as it will 

become the primary 

navigation means for 

the foreseeable 

future. 

Freeing up of 

radiolocation beacon 

allocation (75 MHz 

channel). 

Must protect ILS 

allocations for the 

foreseeable future. 

There may be an 

issue with frequency 

planning of MLS [ref 

NATS comments] 

As more users move 

over to GNSS, more 

bands will be used 

(L5, E5). 

Decommissioned as 

life-time ends – 

availability of 

spectrum therefore 

depends on life-time 

of beacons. 

Cost vs. benefit of 

MLS system is 

prohibitive. 

Table 3-12: Operational requirements for each navigation means 


3.4.5.1 Loran-C 

There are no ICAO or European standards available for Loran-C. 

MLS emerging where 

there is business 

need. 

UK MoD has 

requirements for 50 

MLS systems. If MLS 

is shown to be safer 

than ILS, a mandate 

may be passed in the 

future. 

3.4.5.2 NDB 

Varying strategies exist for the longevity of NDBs in Europe. ICAO wishes to safeguard 

allocations until at least 2015, and EUROCONTROL’s navigation strategy includes this in 

their considerations. However, EUROCONTROL has decided to actively decommission 

NDBs for aviation use; NDBs cannot support RNAV operations due to their relatively low 

accuracy and therefore, they have no role for civil aviation. GPS should replace the 

function of NDBs for GA; how fast this occurs depends on the ability of GA to upgrade to 

GPS (at a higher cost). 

Interference from weather (lightning, precipitation) or night-time effects (increased 

interference from distant stations) reduce the efficiency of NDBs – in addition, the lower 

part of the band is subject to significant interference from broadcasting (and is therefore 

unusable for aviation). Regulation will not be implemented to alter this situation. 

Page 103

3.4.5.3 ILS 

ILS frequencies will be protected for the foreseeable future – even if MLS and GLS are 

implemented, these systems are expensive, and will not provide additional functionality 

for many users (i.e. they have a negative cost-benefit case for new equipment). 

ICAO Annex 10 and CAA Cap 670 define the standards and performance limits on ILS 

operation. 

3.4.5.4 VHF VOR 

EUROCONTROL strategies recommend the rationalisation of the European navigational 

infrastructure – as part of this, the decommissioning of VORs is proposed within 2010 

timescales. With the WRC 2003 decision to allow primary use of the VHF spectrum by 

aeronautical mobile radionavigation services, further pressure is expected to be placed 

for the decommissioning of VORs. 

Note however that issues exist with the full phase-out of VORs (and NDBs). Firstly, 

General Aviation will be forced to equip with GNSS or RNAV computers. A low-cost 

system for GA is essential before this can happen. Secondly, there is the proposed 

reliance on RNAV for navigation, with no back-up to this method. Studies are currently 

on-going in EUROCONTROL investigating the potential impact of a solely RNAV future 

environment. 

Protection is also afforded to, and from, the FM broadcasting services operating in the 87- 

108MHz band. 


The spectrum allocated to MLS by ITU extends from 5000 to 5250 MHz but ICAO 

currently specifies only the sub-band from 5030 to 5090 MHz and reserves the upper 

band for future use. The lower 30 MHz were allocated to GNSS at the World Radio 

Conference in 2000. Fixed Satellite Services operate in the 5090 to 5150 MHz band on a 

non-interference basis. WRC-03 modified Radio Regulation footnotes 5.444 & 5.444A 

and Resolution 114 (Rev.WRC-03) which relates to this band. 


ICAO Annex 10 specifies strict co-channel and adjacent channel geographical separation 

criteria. This becomes an issue when looking at full DME coverage across the ECAC area 

to support RNP-RNAV operations. A regulated PFD (power flux density) may be the best 

way to ensure cross-channel interference is minimised; WRC-03 proposed this solution, 

but no firm decision has yet been taken. 

The ITU in Recommendation M.1639 has determined an EPFD (equivalent power flux 

density) limit for RNSS in the L-Band (particularly 1164-1215MHz), to protect ARNS – the 

methodology can be found in ITU Recommendation M.1642. In the short term, the focus 

is upon the protection of ARNS. In the much longer term, as GNSS becomes more 

prevalent in aviation, it could be argued that the focus will shift to prioritise the protection 

of GNSS signals. This will depend on the ability of the relevant bodies to prove the 

performance of sole-means GNSS-based solutions. 


GNSS is constrained by strong standardisation and regulatory requirements. GNSS 

signals impact on currently used ground-based navigation aids such as DMEs and 

primary radars. In order to protect existing ARNS allocations, the ITU has imposed an 

aggregate EPFD limit on all RNSS signals. 

Page 104

The demand for the L-Band GNSS frequencies will become increasingly widespread 

throughout Europe as the reliance on GNSS for airborne navigation increases. Issues 

surrounding the possible interference from ARNS (DMEs) in the 1164-1215MHz band 

must be resolved in the near future. This is due to problems at high altitudes (when 

several DME stations are visible to the antenna, the in-band signals increase), and this in 

spite of directional antenna. Although the ITU has addressed the issue, there is an ongoing 

discussion on the extent of the problem (the conclusion of which will be important, 

as the introduction of the L5 band at 1176.45 MHz +/-12 MHz for GPS and the E5 band at 

1188-1208MHz for Galileo will have an impact). WRC-03 established Resolutions 609 & 

610 (WRC-03) and Recommendation 608 (WRC-03). Further solutions may include the 

reallocation of the DMEs, or by the further limiting of the power flux density of either 

system. 

• From the perspective of the 1215-1300 MHz band, the situation is complicated. 

The rights of existing ARNS (in the form of primary radars) are defended by 

several parties. Whether this is valid, and if so how to protect ARNS, has 

remained a matter for debate for 3-4 years. 

Although limits have been successfully imposed in the lower L-band to protect DME, the 

technology issues are different here – the military currently uses the GPS allocation inband 

(GPS L2) for precise positioning services and it strongly defends the right to 

maximum signal strength. As Galileo is introduced, a new band (E6) will be used; this falls 

in the middle of the UK’s primary radar frequency pattern. Evidently, if E6 becomes a 

prime civil signal carrier frequency, the effects on ARNS will become more prevalent than 

is currently the case. The UK, through CAA, MoD and Ofcom, is currently looking at this 

issue. ICAO is also preparing studies to resolve the debate. WRC-03 modified Radio 

Regulation footnotes 5.329, 5.331 and established Resolutions 608 and 610 (WRC-03) in 

relation to the use of the band 1215 – 1300 MHz. 

The 1559-1626.5MHz allocations are strongly defended by the relevant aviation bodies 

(e.g. ICAO); although 72 countries (Europe/Middle East) have established fixed services 

allocated to this band (Footnotes 5.362B and 5.362C), the ITU agreed at WRC2000 that 

the usability of GNSS was constrained by these fixed services, and as such, the 

allocation should be ceased as soon as practicable. As a result, in many countries these 

fixed services remain a primary allocation until 2005, and then become a secondary (noninterfering) 

service until 2015, when they shall cease. Note that the UK is not included in 

this footnote (i.e. no fixed services in this band) but neighbouring countries (i.e. France) 

are. 

From the Earth-space perspective, the allocation of 1300-1350 MHz to Galileo ground 

stations is subject to studies in geographical separation criteria between the ground 

stations and radio-navigation aids (primary radars) (WRC2000 – Resolution 607). 

From the socio-economic point of view, there have been major investments in Galileo 

(and EGNOS) by European organisations, agencies and companies – in order to justify 

this, they will want to see solid returns. Political pressure is likely to be brought to ensure 

that GNSS sees increasing demand. 

Page 105


En-route 

Navaid Development Impact on Spectrum Comment 

Loran-C No regulation 

NDB EUROCONTROL Nav 

Strategy recommends 

the decommissioning 

of all NDBs as soon as 

practicable. 

VOR EUROCONTROL Nav 

Strategy recommends 

the decommissioning 

of all VORs, as they 

have a lower accuracy 

than DMEs to support 

RNAV operations. 

DME The ITU has 

determined an EPFD 

limit for RNSS in the L- 

Band (particularly 

1164-1215MHz), to 

protect DME. Possible 

PFD limits imposed in 

future. (Resolutions 

609, 610 (WRC-03) 

and Recommendation 

608 (WRC-03) apply. 

Possible freeing up of 

spectrum for 

broadcasting use 

(Short/Medium 

Wave). 

If this proceeds, VHF 

spectrum should be 

freed for other uses – 

it is recommended 

that aviation 

continues to use the 

spectrum however, 

with ILS, GBAS, VDL 

Mode 2, 3 and 4, and 

VHF voice all 

competing for 

available spectrum. 

Co/cross channel 

interference is an 

issue. Regulation (of 

frequency and PFD) 

may be able to control 

the interference. 

No regulatory issues 

Any decommissioning 

needs to be coordinated 

with 

neighbouring States 

(e.g. France) – 

therefore changes 

should be driven 

through 

ICAO/EUROCONTROL 

. 

Timescales for 

decommissioning vary, 

and will in practice 

depend upon non-civil 

aviation users – e.g. 

GA, Military. 

Strict co-channel / 

adjacent channel 

separation criteria are 

specified in the SARPS 

– meaning that 

frequency planning for 

new DMEs could 

become an issue. 

Page 106

Airport 

GNSS Aggregate EPFD limits 

imposed by ITU on 

RNSS signals, to 

protect existing ARNS 

allocations. 

Marker 

Beacon 

The ITU modified 

Radio Regulation 

footnotes 5.329, 5.331 

and established 

Resolutions 608 and 

610 (WRC-03) in 

relation to the 

protection of ARNS in 

the bands 1215-1300 

MHz. 

Geographical 

separation criteria 

being looked at 

between Galileo earth 

stations and PSR 

locations (WRC2000 

Resolution 607). 

Fixed services to be 

discontinued in the 

1559-1626.5 MHz 

band after 2015. 

ILS No decommissioning 

planned in the 

medium-term, due to 

cost of MLS, and lack 

of accuracy of GNSS 

Landing Systems. 

MLS Full allocation of MLS 

is not taken. In-band 

secondary uses are 

already common. 

Although GNSS is at 

present being limited 

to protect ARNS 

allocations, the 

strategic decision by 

EUROCONTROL to 

move towards GNSS 

‘sole means’ 

navigation ensures 

that any allocation to 

GNSS will be primary 

usage in the long 

term future. 

As such, although 

currently RNSS has 

constraints applied to 

its signal (power 

output); in the future 

this may be reversed 

(as PSR and DME 

become secondary to 

the need for a strong 

RNSS signal in 

aviation). 

Major investment by 

European bodies 

means that lobbying 

power will be strong. 

Expect spectrum 

requirements to 

increase rapidly in the 

long-term. 

No regulation. 

No change likely. No specific 

requirements beyond 

those applying to the 

entire 108-117.975 MHz 

band. 

Dependent on takeup 

of MLS in UK, 

more secondary uses 

could be allowed. 

Table 3-13: Navaid Summary 

3.4.6 Possible Improvements to existing technology 

A decision may need to 

be taken on whether to 

keep 5150-5250 MHz 

for possible MLS use, 

or whether to limit the 

frequency allocation for 

the long-term. 

3.4.6.1 Loran-C 

Loran-C is represented in Europe by NELS – they have plans to develop Loran as a 

communications channel for GNSS augmentation via a system known as Eurofix. This 

provides a low-cost alternative to EGNOS. Although the data rate achievable with Eurofix 

is low, it is sufficient to significantly improve the accuracy and integrity of the user’s 

position fix as a GNSS augmentation fix. 

Page 107

The Eurofix service that is under implementation by NELS is intended ultimately to: 

• be available throughout the entire coverage area of NELS and the European 

Union; 

• meet the requirements for adoption/recognition as a component of the worldwide 

radio-navigation system by the IMO/ICAO; 

• meet the requirements for safety relevant applications for land and maritime 

users. 

Note that Eurofix will certainly not meet the requirements of civil aviation in the ECAC 

area. However, general aviation (in those States currently using Loran-C) may benefit 

from the new system. 

GPS time synchronization of the Loran-C chains and the use of digital receivers may 

support improved accuracy and coverage of the service. 

Also, NELS are mapping the ASF (for propagation errors due to ephemeral effects) in 

Member States – a series of corrections will be available as electronic databases. 

NELS also have plans to extend coverage of Loran to the Mediterranean (2010), Canary 

Islands and Eastern Europe (2015). It should be noted that aviation will almost certainly 

not require Loran-C in these timescales, due to the availability of other navigation sources 

(ref: datalink roadmap). 

Standards 

International standards for Loran-C/Eurofix receivers do not currently exist, although as 

noted above (3.4.6.1), work is underway to standardise Eurofix within RTCM 

specifications. Standardisation and certification of Loran-C/Eurofix receivers would be a 

requirement prior to utilisation of such receivers for safety-critical environments within 

Europe, such as in general aviation. 

3.4.6.2 NDB 

No development work for aviation uses is likely. 

3.4.6.3 ILS 

ILS systems reached relative maturity during the 1950s and 60s. With the advent of MLS 

(and GNSS Landing Systems), it is not likely new ILS systems or technology will be 

developed. 

The main development in recent times is the co-locating of a DME system with the ILS, 

replacing the outdated marker beacons. 

3.4.6.4 VHF VOR 

No improvements are likely. 


Triple pairing (with DME/ILS) may lead to an inefficient use of the spectrum. Without triple 

pairing, MLS may be fitted into the 5030-5090MHz band (with 5090-5150MHz or 5090- 

5250MHz used for MLS expansion). The rest of the band could then be freed for AMSS. It 

should be noted that WRC-03 modified Radio Regulation footnotes 5.444, 5.444A and 

established Resolution 114 (Rev.WRC-03) which relates to this band. 

Page 108


EUROCONTROL’s navigation strategy calls for further provision of DMEs to enhance 

coverage. Roughly 230 DMEs are forecast to be needed in core Europe to ensure full 

coverage for RNP-RNAV operations. 


The introduction of new augmentation systems (such as EGNOS), in addition to extra 

GNSS satellites being launched (GPS2, Galileo), will see greater usage of the allocated 

bands. The overall power of each of these systems is likely to increase; plans already 

exist for GPS L1 and L2 signals to increase in power. 


3.4.7.1 Loran-C 

Not applicable. 

3.4.7.2 NDB 

None known. 


Not applicable. 

3.4.7.4 ILS 

The 108-117.975 MHz band is currently shared between ILS/VORs (108-111.975 MHz) 

and stand-alone VORs (112-117.975 MHz). ICAO proposes to allow the future allocation 

of the ILS portion of the band to GNSS ground-based augmentation services (GBAS) and 

VHF Datalink (VDL Mode 4). GBAS would probably be co-located with ILS equipment for 

the foreseeable future – regulation may therefore be necessary to ensure appropriate 

allocations are given to each technology such that interference is kept to a minimum. 

A new resolution from WRC 2003 provided the approval for the use of aeronautical 

mobile radionavigation services in this band – namely VHF Data Link Mode 4. 

3.4.7.5 VHF VOR 

In common with ILS (see above), VORs may be affected by potential changes to the 

Radio Regulations to allow aeronautical mobile radionavigation services to be allocated to 

the band on a primary basis. As such, VDL Mode 4 may impact upon the frequency 

congestion if it is introduced as planned in the medium-term. 

More information on VHF Datalink Mode 4 can be found in section 5. 


HiperLAN – High Performance Radio Local Area Network – has been ratified by CEPT 

and the ITU for use on a non-interfering non-protected secondary basis at 5150-5250 

MHz. This may be extended to 5350MHz in the future. 

In addition, 5091-5150 MHz is shared with non-geostationary satellite systems in the 

mobile satellite service. It should be noted that WRC-03 modified Radio Regulation 

footnotes 5.444 & 5.444A and Resolution 114 (Rev.WRC-03) which relates to this band. 

Page 109


Internationally, the implementation of UAT (Universal Access Transceiver) for ADS-B will 

impact upon a narrow range of frequencies in-band (thought to be around 966MHz or 

978MHz). Initially, this will affect the USA, but the requirement for global harmonisation 

may see this frequency allocated in Europe in the medium term. 

The MoD uses some of the spectrum for aeronautical communications, following 

agreements with DAP (for non-interference with the primary use of ARNS). 


The introduction and proliferation of Ultra-Wide Band (UWB) solutions has caused 

concern amongst the aviation fraternity, in part because UWB has been unregulated in 

the past. UWB is a low-power, high bandwidth communications method, with bandwidths 

spread over more than 1.5MHz. 

The effects of UWB can be negated by technical solutions – examples include frequency 

hopping or pulsing, thus avoiding the RNSS and ARNS allocated frequencies. However, 

problems still exist with the aggregate effect that thousands of mobile wireless unlicensed 

UWB devices might have on the overall noise floor. The USA has detected the problem 

(as described in a recent IATA paper), and points out that spectrum protection is not 

conducted by the airlines, but by government or international bodies. UWB spectrum is 

part of private spectrum that is overseen in the US by the Federal Communications 

Commission, which has a remit of allowing maximum access for the most users. As such, 

UWB is currently being promulgated through safety-of-life service frequency allocations 

(in particular, from 1559 to 1626.5MHz). 


3.4.8.1 Loran-C 

As the planned EGNOS technology comes on-line, there will be strong pressure for users 

to move to the new augmentation system (in time for the introduction of Galileo, Europe’s 

GNSS) – particularly if the safety case for EGNOS proves favourable for safety critical 

applications. 

3.4.8.2 NDB 

GNSS is likely to replace the requirement for NDBs, particularly as Galileo comes on-line 

circa 2008. 

The take-up of GNSS amongst GA users depends primarily on the availability of low-cost 

solutions. 


Marker beacons are being replaced by DME systems (co-located with the ILS). 

3.4.8.4 ILS 

ILS may be replaced by MLS (Microwave Landing System), where the commercial and 

safety aspects are beneficial. MLS allows for greater accuracy, and negates the multipath 

effects experienced by ILS (off buildings, aircraft etc). 

In time, GNSS Landing Systems (GLS) may become standard – at present, they are able 

to support Category I approaches (work is on-going for Cat II and III). 

There is pressure on the glideslope allocation from other aeronautical mobile services. 

Page 110

3.4.8.5 VHF VOR 

VORs are predominantly used for point-to-point navigation and not widely used for RNAV. 

They will continue to be used in the introduction of a ‘total RNAV’ environment in 

European airspace. The ECAC navigation strategy plans for a mandate for RNP RNAV in 

2010 (although such a date is now unlikely to be met as an announcement of the 

mandate is required 7 years in advance and it has not yet happened) and after this date 

the VORs could be decommissioned. The navigation environment for IFR aircraft would 

then be GNSS and DME/DME. Note that some recent work in EUROCONTROL has 

questioned the feasibility of removing the VORs even after a mandate for RNP RNAV. 

GA would continue to use VORs, since they would be unaffected by the RNP RNAV 

mandate. Pressure on the spectrum from aeronautical mobile services (VDL Mode 4) may 

also create pressure to bring forward the dates for decommissioning. 


The incumbent ILS systems may still meet operational requirements. Alternatively, GNSS 

Landing Systems may replace both ILS and MLS (although these are only capable of 

supporting Category I operations at present, the introduction of Galileo and its 

augmentation systems may increase this to Cat IIIB eventually). 


Although GNSS can provide a sole means of navigation, there is a requirement for a 

ground-based navigation infrastructure to guard against the possibility of interference 

(illegally through jamming, or from natural causes such as ionospheric effects) and for 

safety/redundancy. DME meets the requirements for a relatively low-cost system. Future 

replacement technologies are unlikely, given that DME/DME is the recommended solution 

until 2020. 


None. 

3.4.9 Allocation Sharing Opportunities 

3.4.9.1 Loran-C 

EUROCONTROL and ICAO maintain that certain States still require usage of the Loran-C 

bands for aviation – until it can be demonstrated that aviation use has ceased, their 

position is that the unique allocation to Loran should be retained. 

3.4.9.2 NDB 

Broadcasting and maritime mobile could both make use of additional in-band allocation, 

particularly around the 255-283.5 kHz band. As ICAO has stated it wishes to maintain 

allocations until 2020, these other uses would be subject to usage on a non-interference 

basis. The possibility exists to extend the shared allocation frequencies beyond 283.5 

kHz. Note that any sharing undertaken would also need to be co-ordinated with the 

military, which use mobile beacons. 


No opportunities. 

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3.4.9.4 ILS 

ILS allocations are threatened by the implementation of GBAS and VDL Mode 4 in-band. 

Although GBAS will allow an ILS-like service, the risk for users to move to a GLS solution 

before 2020 is fairly low. Maintaining the ‘status quo’ is most users’ preference, as ILS 

meets most operational requirements, and aircraft are already equipped. VDL Mode 4 

allocations should be co-ordinated with international bodies such as ICAO and 

EUROCONTROL; ILS allocations should not be restricted. 

FM Broadcasting can interfere with the lower end of the localiser spectrum. Sharing of the 

spectrum is difficult, due to the frequency pairing of VOR, ILS and DME. If this frequency 

pairing (or tripling) could be decreased, a more efficient use of the spectrum could be 

achieved; this would in turn enable the introduction of new technologies in-band. 

3.4.9.5 VHF VOR 

The opportunity to decommission stand-alone VORs (whilst de-pairing them with DME 

and ILS) should lead to greater use of the band by other technologies such as VDL Mode 

4. 


Triple pairing (with DME/ILS) may lead to an inefficient use of the spectrum. Without triple 

pairing, MLS may be fit into the 5030-5090 MHz band (with 5090-5150 MHz used for MLS 

expansion). The rest of the band could then be used for AMSS. (See also section 

3.4.6.5). 


The band is heavily populated, with pressure from the MoD’s datalink applications 

(JTIDS/MIDS), SSR/ACAS (1030 MHz and 1090 MHz), UAT (approx 978 MHz), GNSS, 

DME and non-regulated amateur users. (see section 3.3 above for more discussion on 

SSR, ACAS and UAT). 

Reallocation of DME frequencies has been proposed, to free up space for the forthcoming 

GPS L5 band (EUROCONTROL SMA); however, co-location with VORs has meant it is 

impossible until VOR decommissioning circa 2010. Even then, for the L5 band in core 

Europe, reallocation of DME frequency usage may prove impossible. 


GNSS can be divided into three broad areas – the L5 / E5 bands, the E6 (L2/G2) band 

and the E2-L1-E1 band. Each of these poses individual allocation sharing opportunities 

(or threats). 

In the lower L-band (1164 – 1215 MHz), sharing is already planned between ARNS 

(specifically DME and JTIDS/MIDS) and RNSS. There are studies on-going to determine 

the likely interference as L5 comes on-line. The ITU has set limits on the EPFD of the 

GNSS signals, to protect ARNS. The UK is likely to support methodologies enabling the 

equitable and efficient usage of the spectrum within this EPFD limit. 

The E6 (and L2/G2) space-Earth band (1215-1300 MHz) shares the frequency with UK 

civil and military radar systems – issues arising, and allocation sharing opportunities, are 

discussed in previous Ofcom (and the former regulator, the Radiocommunications 

Agency) reports (see refs). It should be noted that WRC-03 modified Radio Regulation 

footnotes 5.329, 5.331 and established Resolutions 608 and 610 (WRC-03) in relation to 

the use of the band 1215 – 1300 MHz. 

The E2-L1-E1 band (1559-1626.5 MHz) is subject to an ICAO policy of no new in-band 

allocations. The protection of GNSS signals from harmful interference is of major concern 

Page 112

to aviation. As discussed in section 3.4.5.7, allocations are actually being moved out-ofband 

over the next few years (i.e. fixed services cease usage by 2015). The issue 

currently is whether other technologies such as UWB, or harmonics from certain other 

frequencies (e.g. TV broadcasting operating around 800 MHz), will affect operations (and 

are therefore allowable). This is currently being researched at an ICAO and 

EUROCONTROL level. 

3.4.10 Summary Of Possible Overall Spectral Efficiency Improvements 

This section attempts to highlight any improvements that could be made to increase 

spectrum efficiency. The possible mechanisms for carrying out these improvements are 

discussed in further sections below. 

LORAN-C – the allocation is fixed on a central frequency, which will not change in the 

foreseeable future (due to non-aviation requirements). Although there is a possibility of 

reducing the bandwidth, the likelihood is that 20 kHz is the minimum required to provide a 

safety-of-life service (e.g. to maritime users), and therefore should be maintained. 

NDB – competition exists from broadcasting and maritime mobile. Broadcasting at the 

upper and lower ends of the band may be able to increase its allocation if the 

decommissioning of NDBs permits. ICAO recommends that the overall allocations are 

maintained until 2020 – nevertheless, the 255-283.5 kHz band is currently shared 

between MRNS, ARNS and broadcasting, thus constraints on broadcasting may be able 

to be removed in-band before 2020, or more allocation sharing permitted in frequencies 

over 283.5 kHz. General Aviation is the main blocking point to the decommissioning – 

methods should therefore be found to replace the GA requirement for NDBs. Scenarios 

could include: 

• Equipping GA with RNAV capability (in practice, an RNAV computer and the 

ability to receive multiple modes of navigation inputs) or; 

• Equipping GA with GNSS capability. 

Marker Beacons – no change foreseen. 

ILS – the ILS frequency allocation shall remain protected; channelisation is fixed. 

However, non-interfering secondary allocations may be granted – local augmentation 

systems for GNSS, such as GBAS for landing systems, may be allocated frequencies 

within ILS bands. Geographical separation criteria should be implemented to ensure 

efficient frequency usage. However, with the withdrawal of VORs, it may be more prudent 

to site GBAS in the upper part of the allocation to VHF ARNS. 

VOR – in common with ILS, channelisation is fixed. The frequency allocation is likely to 

remain; however, actual usage will decrease in the long term as VORs are 

decommissioned. Plans should be drawn up on how best to re-use the available 

frequencies; competing services include VDL Mode 4 datalink, GBAS and ILS. Again, 

General Aviation has current requirements for VORs; replacement strategies will be 

identical as those for NDBs. 

DME – due to the hard double or triple-pairing with ILS, MLS and VOR, DME allocations 

can be very inefficient. Reduction of the requirements for triple pairing (due to 

decommissioning of the VORs) may lead to greater spectral efficiency. Possible 

opportunities therefore include: 

Investigating the efficiency savings made by de-tripling or de-coupling the ILS, MLS, VOR 

and DME frequencies where appropriate. 

In the medium-term, the usage of the new E5/L5 frequencies (even with the limits 

imposed) will lead to interference between GNSS and DME. The solution of moving all 

DME out of the GNSS band has been found to be unworkable in Europe. However, this 

Page 113

may not be the case for UK airspace, and a similar study should be undertaken to identify 

whether it is possible to move all DME into the 960-1164 MHz band. Note that the 

introduction of UAT in Europe would put further pressure on the band 10 – at present, this 

does not seem likely before 2012. 

MLS – decisions should be taken on the operational requirement for the further uptake of 

MLS. If no firm operational or business need for further installations is foreseen in the UK, 

the upper end of the allocated C-band could be re-examined, with a view to more 

efficiently allocating present secondary services through the removal of the ARNS 

constraints. Possible opportunities therefore include: 

• Identifying future requirements for MLS in the UK – from the point of view of 

safety, and for pure capacity requirements – then, if possible, review upper MLS 

band allocations. 

GNSS – the carrier frequencies of GNSS are fixed internationally, and are likely to remain 

in place in the long term. Channelisation and bandwidth are reasonably fixed. However, 

some debate exists on the power of the individual signals, and their effects on existing 

ARNS. Due to aviation’s specified future reliance on GNSS-based navigation solutions, it 

may be unwise to impose too many limits on the signals. Temporary PFD limits may be 

acceptable to allow the transition from point-to-point navigation aids to GNSS-based 

RNAV environments. Whatever decisions are taken will be at an international level; as 

such, Ofcom’s role would be as a participant representing UK interests in the discussion. 

10 Further information on UAT can be found in the SSR section above (3.3.8) 

Page 114

3.4.11 Conclusions and Recommendations 

3.4.11.1 Summary of Developments 

Navaid Development Impact on spectrum Comment 

En-route Loran-C No civil aviation 

Possible freeing of Note that maritime and 

regulatory support. EC (relatively small) others use Loran-C as a 

and EUROCONTROL spectrum for alternate primary navigation aid. Any 

do not foresee a role for users (or further spectrum reallocations 

Loran-C in the future allocations on a should take into account 

navaid mix. ICAO 

secondary non- the non-aviation 

recommends retention of 

allocation for RNS, but 

allows secondary users 

on a non-interfering basis. 

interfering basis). requirements. 

NDB 

VOR 

Introduction of Eurofix for 

GNSS augmentation. 

Decommissioning of NDB 

as part of shift to RNAV 

environment in Europe 

(based on DME and 

GNSS). 

Decommissioning (in the 

UK) is dependent on GA 

take-up of alternate 

navigation means (most 

likely GNSS-based 

solutions). 

Strategy for European 

application of RNP-RNAV 

calls for decommissioning 

of VORs Europe-wide. 

Pressure on VHF 

spectrum from 

communications 

applications. 

DME Full DME coverage 

planned Europe-wide for 

RNP-RNAV operations. 

Freeing of 

aeronautical NDB 

spectrum for re-use by 

alternate services 

(e.g. maritime mobile, 

maritime 

radionavigation, 

broadcasting). 

A slow-down in 

reallocation 

opportunities would 

result. 

In medium-term, 

reallocation of VHF 

band to 


services (data and 

possibly voice). 

As VORs are deemed 

surplus to 

requirements in the 

medium-term, there 

may be a strong 

political lobby to free 

the spectrum for 

communications use 

Increasing demand on 

L-band. 

Very limited aviation use. 

Radiobeacons may still be 

in use for non-aviation 

purposes (e.g. oil platform 

locators, military uses, 

maritime locators). Studies 

on the scale of these 

diverse applications are 

required before spectrum 

reallocation. Note that 

ICAO policy calls for 

international allocation of 

ARNS for use by NDBs 

until at least 2020. 

Ofcom to stimulate GA’s 

uptake of GPS (through 

CAA). 

Any decision must be coordinated 

at a regional level 

– neighbouring States must 

be consulted. Therefore, 

Ofcom should lobby 

EUROCONTROL / ICAO 

to put in place the 

necessary processes for 

change. 

Possible clearing of lower 

DME frequencies. 

Page 115

Airport 

GNSS 

Marker 

Beacons 

Introduction of L5 and E5 

frequency bands for 

GNSS. 

Introduction of L5 

frequency band (1176.45 

+/- 12 MHz) and E5 

frequency band (1188- 

1208 MHz) circa 2010 

Strong European lobby 

for increased use of 

GNSS as ‘sole means’ of 

navigation in long-term, 

and primary means 

(supported by DME/DME) 

in the medium-term. 

Development of GNSS, 

SBAS and GBAS for use 

in precision landing 

systems. 

Replacement by full DME 

coverage (to allow RNAV 

terminal operations). 

ILS Maintain frequency 

requirements (in the lower 

VHF band) due to 

operational need and 

socio-economic case. 

MLS 

MoD has plans to equip 

50 MLS in UK; LHR has 

MLS in service – other 

airports may follow. 

Benefits (operationally 

and from a safety point of 

view) exist – however, the 

CBA is not strong enough 

to drive equipage. 

Possible replacement by 

GNSS Landing System 

(GLS). 

Triple pairing 

(MLS/ILS/DME) is an 

issue for spectrum 

efficiency. 

Issue of interference 

with GNSS. Possible 

reallocation of DMEs. 

Careful planning of 

alternate uses is 

required – GNSS is 

expected to be the 

primary application in 

the medium-long term. 

Protection of GNSS 

bands. Possible 

reallocation of DMEs. 

VHF spectrum used 

for GBAS (same 

frequencies as ILS) – 

may be an issue 

where ILS and GLS 

are both required. 

Spectrum to be freed 

in medium-term for 

alternate uses. 

Protect frequency 

allocations for ILS 

(from GBAS and VDL 

Mode 4) 

MLS spectrum will be 

locally used in the 

coming years. It 

should be protected 

from in-band 

interference from 

other applications in 

the UK. 

MLS spectrum 

(internationally) would 

be under pressure if 

GLS is proved to meet 

performance 

requirements as MLS 

would then be surplus 

to requirements. 

If this requirement 

were removed, it 

would enable better 

frequency planning. 

Optimum allocation of 

DMEs is critical for the near 

future. Recommend Ofcom 

to push for studies into the 

most efficient allocation. 

Possible VOR/DME 

unpairing as VORs are 

decommissioned? 

Optimum allocation of 

DMEs is critical for the near 

future. Recommend Ofcom 

to push for studies into the 

most efficient allocation. 

MLS offers a completely 

different spectrum, with 

opportunities for growth. 

Possible promotion of a 

move to MLS. 

ILS is a mature common 

system – avionics have 

been long deployed. Any 

changes (MLS or GLS) will 

require very strong cost or 

safety cases. 

MLS avionics are relatively 

expensive – with ILS being 

fully deployed, the status 

quo makes an attractive 

alternative. 

The US Federal 

Radionavigation Plan calls 

for the movement to GLS 

(no future MLS installations 

are foreseen). Europe 

believes significant issues 

still exist with GLS; 

therefore MLS is still viable 

replacement for ILS in 

Europe. 

Studies should be initiated 

assessing the impact of this 

de-tripling. 

Page 116

Table 3-14: Summary of Developments 

3.4.11.2 Recommendations 

Recommendation 3.21: Ofcom should work with the CAA to ensure the timely 

decommissioning of non-operationally required radio navigation aids, in particular, NDBs 

and VORs. The following caveats apply: 

• The requirements of General Aviation and the Military for NDBs and VORs in the 

UK must be urgently addressed; 

• The impact of an RNAV only environment should be assessed, particularly from 

a safety and security viewpoint. 


Costs of Equipment – Ground: The ATSP (NATS UK or specific airport authorities) has 

the responsibility to provide navigation aids for aircraft in their airspace/airport. Costs to 

be borne include: the original purchase (capital costs), maintenance costs (annual costs), 

and replacement costs (at the end of the navigation aids’ lifetime). 

Looking at the en-route environment, these costs include DME, VOR and NDBs. 

Evidently GNSS is not part of this structure (co-ordinated at an international level). Table 

3-15 shows the approximate annual cost for the UK (at 2002 prices). The table assumes 

a 15 year lifespan for navigation aids, meaning that 7% must be replaced year on year. 

Annual Total Annual 

Number Lifespan (yrs) Capital Cost Running Cost Cost 

DME 48 15 £ 70,000 £ 1,700 £ 0.31 M 

VOR 50 15 £ 170,000 £ 7,700 £ 0.97 M 

NDB 11 15 £ 25,000 £ 1,700 £ 0.03 M 

Annual Cost £ 1.31 M 

Table 3-15 – Annual En-route Navigation Infrastructure Costs 

The total cost of maintaining the UK en-route navigation infrastructure is therefore 

approximately £ 1.3 M per annum. The potential savings from decommissioning VOR and 

NDB are in the order of £ 1.0 M per annum. 

When we add in the UK airport environment, this annual decommissioning saving 

becomes more pronounced (see Table 3-16 below), being approximately £ 1.8 M. 

Annual Total Annual 

Number Lifespan (yrs) Capital Cost Running Cost Cost 

DME 66 

75 (incl. 24 

15 £ 70,000 £ 1,700 £ 0.42 M 

VOR TACANs) 15 £ 170,000 £ 7,700 £ 1.45 M 

NDB 118 15 £ 25,000 £ 1,700 £ 0.37 M 

Annual Cost £ 2.26 M 

Table 3-16 – UK Navigation Aid Costs (Airports and En-route) 

Note that this should be balanced against requirements for extra DMEs to support RNAV 

operations. However, as can be seen from the tables above, the annual and capital 

expenditure for DMEs is far less than for VORs. 

In the airport environs, the cost of equipment has an increased influence over the choice 

of system. Part of the reason for the slow up-take of MLS is the high cost of the system 

when compared against ILS – and this coupled with the long lifetimes of ILS equipment. 

Page 117

Costs of Equipment – Air: Although there are considerable savings in ground 

infrastructure costs if VORs and NDBs are de-commissioned, there are substantial 

airborne equipment costs, particular for GA operators. In the case of airlines, which have 

a mandate for RNAV equipage, it is unnecessary to examine the costs. GA, as mentioned 

in the scenarios above, currently has an exemption. In order to decommission VORs and 

NDBs, and move to a complete RNAV environment, this exemption would have to be 

ceased. 

Standalone RNAV Equipment is manufactured by; inter alia, Garmin, Bendix King and 

UPS Aviation Technologies. Typical sample costs covering the entire standalone RNAV 

equipage list include the following: 

Apollo GX60 £ 3,000 by UPS Aviation Technologies 

KLN900 £ 8,100 by Bendix King 

GNS530 £ 8,600 by Garmin 

For some GA IFR (Instrument Flight Rules) users, the provision of P-RNAV and RNP 

RNAV navigation capabilities will be achieved through these standalone RNAV navigation 

units. The cost of a standalone RNAV (including GPS) unit for users in this category is 

estimated to be approximately £ 10,000. 

For cost analysis, aircraft are grouped into the following approximate categories: 

� T0: Very light single engine aircraft / non-powered aircraft; 

� T1: Light single engine pressurised aircraft (piston/turboprop); 

� T2: Light multi-engine pressurised aircraft (piston/turboprop); 

� T3: Large turboprops; 

� J1: Light business jets; 

� J2: Midsize business jets; 

� J3: Commercial jets and large business jets. 

The following table 3-17 summarises the assumed component costs for each aircraft 

type. 

T0/T1 

Initial Cost 

T2/T3/J1 J2/J3 

GPS Receiver £ 4,000 £ 10,000 £ 12,500 

DME £ 11,000 £ 11,000 £ 22,500 

FMS £ 0 £ 35,000 £ 85,000 

Installation Costs £ 3,200 £ 3,200 £ 26,500 

Crew Training £ 130 £ 130 £ 30,500 

Documentation £ 0 £ 0 £ 13,500 

Certification £ 500 £ 500 £ 500 

Maintenance 

Annual Costs 

10% 10% 10% 

Database £ 22 £ 22 £ 1000 

Table 3-17 – Aircraft Component Costs 

Page 118

Notes: 

• The costs are not dependent on whether the change is to P-RNAV or RNP 

RNAV. The cost difference between these upgrades is dependent upon the 

number of additional units required. 

• For T0/T1 it is assumed that a combined GPS/RNAV computer is purchased 

rather than separate GPS and FMS. 

• This cost would be zero for J2 and J3 if the requirement for AFM change is 

removed. 

• Maintenance is only included for new avionics. 

• Database costs are additional to current costs. 

• Military costs are not presented, due to lack of information. 

Cost Recovery: CAA DAP, acting as agent for Ofcom, charges licence fees for 

navigational aids in the UK. This fee is charged by the number of frequencies used by 

each individual navigation aid at the declared location. In addition, the ATSU also pays for 

the purchase of the navigation aid, and any maintenance or upkeep necessary. 

The recovery of all costs on ground-based radio-navigation aids has traditionally been via 

route or airport charges on the aircraft using the service; this is likely to remain the case in 

the future. 

For route charges, the difficulty is examining exactly what factor ARNS plays; they are 

calculated based on the overall service, and not only with reference to the navigation 

aids, since for RNAV there is no way to identify which en-route navigation aids are used 

by each individual aircraft. 

For the airport domain, the charge structure is easier since the tower should have records 

of which approach procedure each aircraft uses; navigational aids are generally tied into 

approach procedures, and therefore use of navigational aids can be calculated – e.g. ILS 

approach will use ILS (localiser and glideslope) and possibly DME; NDB non-precision 

approach will only use an NDB etc. 

Airborne equipment costs, where retrofitting is required, are recovered as part of 

customer charges. The obvious exceptions are the military and GA communities, where 

little or no primary cost recovery exists. This then presents a problem in encouraging 

these communities to move to new, more spectrally efficient, technologies. 

Regulatory impact 

Regulatory Authorities: The regulatory authorities involved with the lobbying and 

promoting of aviation RF requirements have traditionally taken a defensive stance when 

dealing with the allocation of spectrum. This is not necessarily unreasonable since the 

safety criticality of a civil aircraft’s navigation systems is very high, particularly in the 

landing phase of flight. 

From ICAO’s ‘Position for ITU WRC2003’ document: 

“The ICAO position aims at securing availability of radio frequency spectrum to meet civil 

aviation requirements for current and future safety-of-flight applications. In particular, it 

stresses that safety considerations dictate that exclusive frequency bands must be 

allocated to highly critical aeronautical systems and that adequate protection against 

harmful interference must be ensured.” 

In the UK, a balance is struck between the MoD and CAA DAP in determining the 

assignment of ARNS applications to spectrum. In general, this partnership works in 

providing equitable use of the frequency to each user. 

Page 119

However, in recent years, the rapid and fast-changing uptake of radio spectrum by new 

services (using broadband, hiperLAN, AMSS technologies etc) has caused a shift in 

thinking. The ITU no longer accepts the long-term ‘hoarding’ of frequencies; with WRCs 

scheduled every four years and a continual cycle of preparation in regional organisations, 

the ITU is able to consider new requirements and make the necessary changes to the 

Radio Regulations. An example of this is the MLS frequency allocation (5000-5250MHz), 

where only the bottom half of the band is actually used by ARNS; pressure is growing for 

the unused portion to be reallocated on a primary basis. 

Balanced against this is the current tendency to allocate bands to services, without 

adequately judging the viability of sharing the allocation. The prime example is UWB, 

which impacts several RNSS/ARNS bands with low power interference; the cumulative 

effect of this interference may degrade RNSS signals as UWB proliferates. 

The scenario involving decommissioning of VORs and NDBs would face resistance from 

regulatory authorities – ICAO wish to maintain the allocations roughly 10 years past the 

expected operational need. Any decisions taken should take this factor into account. 

Public Perception: The short-term commercial considerations, so important in other 

areas of frequency management (such as fixed services), do not apply to ARNS. 

Although airlines (the eventual customers) operate reasonably short-term individual 

policies, when they are considered as a body the requirements on air traffic services 

change fairly slowly, particularly when discussing the removal of certain services. 

From the public point of view, the availability and reliability of safety-of-life services in 

aviation is taken for granted. Any reduction in the functioning of these services would not 

be tolerated. As an example of this, the new GNSS solution (Galileo) has been developed 

partly to allay fears that European users were relying on a US Military system with signals 

that could be degraded if needed by the US Military (e.g. in wartime). Therefore, a 

European civil system was designed to give unhindered access and performance. 

When looking at decommissioning VORs and NDBs, an interesting point is raised 

regarding the redundancy of RNAV – with no point-to-point navigation aids available, the 

flight crew would have no back-up ‘first principles’ method if RNAV was incapacitated. 

Safety studies are currently on-going to examine this point. If issues are found, it may 

mean a reprieve for VORs. 

The application of pricing 

Ofcom, following a recent review of spectrum management, has been tasked with 

encouraging greater spectrum efficiency through the use of administrative incentive 

pricing (AIP) – prices set by the regulator that should reflect the opportunity cost of 

spectrum use (thereby providing effective incentives for efficient use). AIP can influence 

both the allocation of spectrum, and the assignment of spectrum rights; however, as 

ARNS and RNSS allocation is generally governed by international agreements, it is in the 

assigning of rights that AIP has the most leverage. 

Balanced against this purely economic viewpoint is the cost of the social use of spectrum 

– in short, the ‘opportunity cost’ of having a safety-of-life service of adequate performance 

versus losing this safety-of-life service due to poor performance. In airborne navigation, 

this ‘opportunity cost’ in most cases outweighs any considerations of pure pricing. Indeed, 

in the recent Ofcom study on spectrum pricing it was suggested that any services 

internationally allocated on an exclusive basis which do not experience in-band 

congestion should be exempt from AIP. According to Cave, the effective opportunity cost 

to individual users of ARNS is usually zero, due to mandated standards for safety-of-life 

services – most often corresponding to a particular equipage on-board the aircraft (with 

the notable example of 8.33 kHz vs. 25 kHz channel spacing in the VHF band, discussed 

in aeronautical comms below). This applies to VORs, ILS and DME. 

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Where technology choices do exist for the individual user, differential licence fees could 

be applied to encourage a move to a more spectrally efficient system. It may be possible 

to apply pricing measures to encourage a transition away from NDBs and VORs. In the 

UK, this could support the move from point-to-point navigation to RNAV or GNSS-based 

navigation. Although civil aircraft have been mandated to move to the new (more 

spectrally efficient) solution, exemptions exist for military and General Aviation on the 

basis of the cost of upgrading. The problem remains for how to apply pricing – there is no 

easy way to tell who is using which en-route navigation aids. The airport domain is easier, 

since the tower already charges aircraft depending on which type of approach they use 

(ILS, non-precision NDB etc). For this area, additional AIP could be added to the 

approach charges, to encourage users to move to a more spectrally efficient solution. In 

practice, this would entail applying AIP to NDB approaches, in co-ordination with the 

airport’s managing authorities. However, if pricing is to be used, it seems best simply to 

charge higher fees to aircraft that are not equipped with DME equipment (the costs for 

this were shown above and these could be used as the basis for charging). Given the 

long lead times resulting from regulatory and safety of life considerations, a possible 

approach is to apply pricing measures with a view to forcing a change over a relatively 

long time period (i.e. 10 years). This might mean, for example, applying higher charges to 

new aircraft if not equipped with DMEs. Then, the higher charges should be applied after 

a 5 to 10 year period to all non-equipped aircraft. This at least provides an incentive for 

purchasers of new aircraft and gives a reasonable time for retrofit aircraft to comply. 

Recommendation 3.22: Ofcom should recommend to the CAA that a feasibility study be 

carried out into the potential for rationalising the DME spectrum to avoid the requirement 

for more spectrum elsewhere in the future. In practice, this would entail: 

• Looking at long-term allocations for DME, in light of the proposed DME/DME 

infrastructure, and the proposed implementation of the GNSS L5/E5 band (1164- 

1215 MHz); 

• The feasibility and practical implications of the de-pairing of VOR, DME and ILS 

frequencies should be investigated, to allow better spectrum planning in the Lband; 

• The feasibility and practical implications of de-tripling of ILS/MLS/DME should be 

investigated, to free up spectrum for more efficient allocations; 

• Ofcom should work in conjunction with the CAA to ensure that studies are 

undertaken into the possible effects of UAT (ADS-B datalink) on DME 

frequencies 11 . 


The requirements of this recommendation are primarily technical in nature and require 

initial study by the aeronautical industry. No immediate applications for pricing have 

therefore been identified. 

3.4.12 Note on Mobile Navigation Aids – Radar Altimeters 

Radar altimeters operate in the C-band at 4300 MHz (+/- 100 MHz). This ARNS allocation 

(4200-4400 MHz) applies to all three ICAO regions. 

Airborne radar altimeters are used at low altitudes to provide a greater accuracy than 

barometric altimeters. In particular, they are used in automatic landing systems on 

11 

Note that it is unlikely that UAT will be implemented in Europe in the medium-term (i.e. 

before 2012). 

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modern civil aircraft to determine the start of the flare procedure, or as inputs to the 

Ground Proximity Warning System (GPWS). For these applications, both of which have 

high ‘safety-of-life’ criticality, good performance and low interference are vital. The use of 

a wide frequency band (200 MHz) is an essential feature in achieving high orders of 

interference rejection, particularly in densely populated areas. ICAO Doc 9718 states 

although studies in 1990 reported that accuracy requirements may be met with less than 

200 MHz bandwidth, it now appears that future requirements may require more than 200 

MHz. 

No substitutes exist for this technology – it has a unique role in the modern aviation 

operational concept. 

Standards for radar altimeters have been in existence since the mid-70s (RTCA MOPS 

for radar altimeters and GPWS – DO-155 and DO-161A). 

Issues 

Although use of the band is exclusively reserved for airborne radio altimeters (and the 

associated transponders on the ground), passive sensing in the earth exploration-satellite 

and space research services is allocated on a secondary basis. Research has been ongoing 

since 1998 into the issues of band-sharing with space-based passive earth 

sensors. Studies have recommended that the use and development of ARNS should be 

unconstrained by EESS, and that no protection can be claimed by EESS. As the power 

differential is reasonably large in favour of radar altimeters, interference from EESS is 

minimal. The issue is therefore whether ARNS requires such a large bandwidth. As 

mentioned above, ICAO believes it is an essential feature in ensuring the performance 

and accuracy of the safety-of-life critical ARNS, and therefore should be maintained. 

As radar altimeters experience interference in proportion to the density of surrounding 

traffic (particularly above or below), it is likely that performance will be degraded in the 

future as traffic density increases. Therefore, proposals have been developed to allocate 

further bandwidth to ARNS – this may be debated at WRC2007. 

3.4.13 Note on Mobile Navigation Aids – Airborne Radar 

Airborne Doppler Radar operates in the bands 8.750 – 8.850 GHz and 13.25-13.4 GHz. 

Airborne Weather Radar operates in the band 5.350 – 5.470 GHz. These allocations 

apply to all three ICAO regions. Other uses of the same band for earth explorationsatellite 

and space research do so as long as they cause no interference with, or 

constrain, the aeronautical use. 

Doppler navigation systems are widely used for specialised applications such as 

identification of ground speed and flight track control. 

Current weather surveillance is based on an onboard weather radar system capable of 

detecting convective activity, precipitation density and turbulence in the aircraft vicinity. 

The purpose is linked directly to the safety of flight by providing a means of avoiding 

potentially harmful weather conditions. It also supports greater flight efficiency and 

passenger comfort. 

The main advance is expected to be the progressive introduction of predictive windshear 

facilitated by the advance in the Doppler systems employed by weather radar. Wind shear 

is a sudden change in wind direction or velocity, often found around thunderstorms or in 

unstable atmospheric conditions. Its worst representation are the so called microbursts, 

vertical columns of air rapidly descending towards the ground, and extremely dangerous 

because they may be capable of overcoming the maximum climbing performance of the 

aircraft. 

Local weather conditions (including fog, smoke, wind and lightening activity) can be 

obtained via voice communications from the ground or other aircraft. 

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The implementation of ADS and up and downlink communication technologies (see 

sections 3.3 and 5) makes it possible to share weather information both air-air and airground. 

This makes it possible to provide enhanced weather information without separate 

equipage with airborne radar. However, the overall requirement for airborne radar will not 

decrease since there will still be a need for gathering of basic data (i.e. a high proportion 

of aircraft still have to be equipped in order for there to be valid data to exchange via data 

link). Hence, it is concluded that the requirement for airborne radar will be maintained, is 

closely related to safety of life applications, and therefore there is little scope for spectrum 

efficiency measures in this band. 

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4 Maritime Radiodetermination 


4.1.1 Background 

The requirements of the maritime industry depend heavily upon the economic 

development and activity within this industrial sector. In recent years the sector has 

shown some slight economic and industrial growth. Profit margins have improved and 

financial investment in the sector is increasing. Developments and implementations of 

new technologies have generally been restricted to the minimum needed to comply with 

administrative and safety requirements, in particular the implementation of GMDSS to 

larger vessels. 

In the short term most companies are likely not to have ambitious plans for the 

implementation of new radar technologies; however there is recognition from within the 

industry that moves need to be taken to comply with recently proposed tighter restrictions 

on spurious emissions as proposed by the ITU. The typical replacement cycle for a ship’s 

radar is of order 10 years, which inevitably leads to slow uptake in recent technological 

changes, unless mandated or where obvious (financial) efficiency gains can be made. As 

an example, in January 2003, the ITU mandated a new standard for spurious emissions 

from maritime radar equipment 12 . This applied to all new equipment as of 1 January 2003 

but the timescale for all radar equipment to conform to the new specification is 1 January 

2012. 

Most freight and passenger operators agree that in the long term there is the need for the 

further integration of maritime transport with inter-modal transport. This applies 

particularly to freight transport and requires that no intermediate handling of goods takes 

place at the modal switch, thereby reducing the total transportation time of cargo and 

reducing errors in handling at intermediate steps. 

Both in freight transport and in passenger transport, the trend towards the development of 

inter-modal, door-to-door, services is one of the most important issues. This development 

of inter-modal services, together with the enlargement of ships to gain economies of scale 

advantages are probably the most important developments envisaged for the maritime 

industry. Information is essential for the efficient planning and co-ordination of land 

transport with maritime transport. Delays will increase the turnaround times of vessels in 

ports, thereby decreasing the efficiency of the vessel and resulting in an increase in the 

cost of transportation. 

Efficient ship-shore communications and the availability of electronic navigational aids 

can facilitate efficient planning of port activities and could help ensure that ships are 

managed within designated time slots. 

Developments in the integration of land-based information (fleet owner, freight operator, 

fishing agency etc.) with maritime/vessel-based information are required to achieve 

optimal operational efficiency. This will lead to the creation of “integrated ship 

management systems” and will improve efficiency of ship operations, which in turn will 

reduce turn-around times in ports and therefore reduce operational expenses of fleet 

owners. 

12 The out-of-band roll-off was changed from 20 to 40dB per decade. 

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Maritime transport has always been important to the United Kingdom as an island nation. 

In general, the development of the transport industry depends heavily on the development 

of the economy as a whole. Transport demand, for both cargo and passengers, for all 

modes of transport has shown uninterrupted growth since 1970. 

Maritime transport, and in particular maritime cargo transport, experienced a growth of 

35% in the late 1970’s and the start of the 1980’s, but has diminished in absolute terms 

slightly in subsequent years. Maritime transport is very important for trade between 

Europe and America/Far East countries and for transport between the different European 

countries. 

Within the EU the European Commission has developed and is maintaining a Common 

Transport Policy, which has been implemented in order to ensure that the transport sector 

can take full advantage of the implementation of the Single Market. 

This Chapter has addressed the spectrum management and socio-economic issues 

concerned with maritime radar systems and the associated equipment used to improve 

the visibility of certain key structures. At the end of this Chapter the Consultant has 

included a number of recommendations which the UK Office of Communications may 

wish to consider. 

4.1.2 Frequency Allocations 

Maritime radiodetermination systems (with the exception of ship berthing radar – please 

see later discussion on this matter) all operate in three distinct frequency bands. 

3 GHz 

Both the Region 1 and UK frequency allocation tables allocate the frequencies 2900 – 

3100 MHz to Maritime Radionavigation as a primary service. Footnote UK98 states that 

this frequency band is limited to maritime radars. 

In the UK, this band is shared on a co-primary basis with Aeronautical Radionavigation 

and on a secondary basis with Radiolocation. The band is also used by the MoD for the 

radionavigation and radiolocation services. 

5 GHz 

The UK frequency allocation tables allocate the frequencies 5460 – 5650 MHz to Maritime 

Radionavigation as a primary service. In the UK frequency allocation table, footnote UK 

105 adds that the maritime radionavigation service is limited to shipborne and associated 

land based radars. This allocation is shared in the UK on a co-primary basis with 

Aeronautical Radionavigation and on a secondary basis with Radiolocation and the Land 

Mobile service on the frequencies 5460 – 5470 and 5470 – 5650 MHz respectively. 

The Region 1 allocation for this spectrum is to Radionavigation as a primary service and 

radiolocation as a secondary service on the frequencies 5460 – 5470 MHz, and to 

Maritime Radionavigation as a primary service and radiolocation as a secondary service 

on the frequencies 5470 – 5650 MHz. 

According to the UK frequency allocation table, frequencies between 5350 and 5470 MHz 

are used by the MoD for the radiolocation service. Meteorological radars are allowed 

between 5600 and 5650 MHz, and military radars may operate in this band on a 

secondary basis. 

9 GHz 

Both the Region 1 and UK frequency allocation tables allocate the frequencies 8850 – 

9000 MHz to Maritime Radionavigation on a primary basis, though footnote UK4 indicates 

that these frequencies are assigned to the MoD in the UK (and are thus outside the remit 

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of this study). These frequencies are shared in the UK with the Radiolocation Service on 

a co-primary basis. 

Again, both in Region 1 and in the UK the frequencies 9200 – 9300 MHz are allocated to 

Maritime Radionavigation on a primary basis and are shared with the Radiolocation 

Service on a co-primary basis. 

In addition, the frequencies 9300 – 9500 MHz are allocated to Maritime Radionavigation 

on a primary basis in the UK, but this is not a Region 1 allocation per se as the Region 1 

allocation in this frequency range is simply for Radionavigation on a primary basis and 

radiolocation on a secondary basis. These frequencies are shared with Aeronautical 

Radionavigation (in the UK) on a co-primary basis and Radiolocation on a secondary 

basis. This band is the most commonly used for maritime radar with over 800,000 shipborne 

radars believed to be in operation. 

The UK frequency allocation table, footnote UK120, indicates that the use of the 

frequency range 9200 – 9500 MHz for maritime radionavigation is for shipborne radar and 

RACONs with harbour radars by special arrangement. 

The MoD is allocated the range 9200 – 9300 MHz for the radiolocation service and the 

range 9300 – 9500 MHz for the radionavigation service. 

4.2 Ground Based 

4.2.1 MSR (Maritime Surveillance Radar) 

Ground based Maritime Surveillance Radar (MSR) is used to track the movement of 

shipping in and around coastal (and to a lesser extent in-shore) waterways. Radars are 

employed by a number of organisations such as the Maritime and Coastguard Agency 

(MCA) who have 3 radars covering the English Channel, as well as operators of ports and 

docks. In addition, some private companies operate radars (and other services) to provide 

a set of services known as Vessel Traffic Services (VTS). VTS is particularly appropriate 

in the approaches and access channels of a port and in areas having high traffic density, 

movements of noxious or dangerous cargoes, navigational difficulties, narrow channels, 

or environmental sensitivity. 

4.2.1.1 Technology Description 

The principles of operation of marine primary radars are fundamentally the same as the 

aeronautical systems described elsewhere in this report and thus the technological 

background has not been repeated for the sake of brevity. There are, however, a number 

of significant differences in the way in which radar is employed in the maritime sector as 

opposed to the aeronautical sector: 

• Velocity of traffic: The velocity of maritime traffic is much lower placing less 

stringent demands on update rate. Also this difference may provide some 

increased tolerance to occasional loss of detection. 

• Interference suppression: Maritime radars are required to suppress high levels 

of emissions from adjacent radars. In the case of aeronautical radar, a few, wellspaced 

ground-based radars are used to plot the movements of various aircraft. 

Whilst facsimiles of this exist for ground based maritime radars insofar as there 

are networks of ground-based maritime radars tracking vessels in and out of 

ports for example, the majority usage of maritime radar is on the vessels 

themselves to aid navigation and safety in busy waterways. Thus maritime radars 

rely heavily on their interference suppression (pulse repetition frequency 

discrimination) circuits to minimise the effects of interference caused by other 

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adars operating in their vicinity. Note, however, that all types of radar may suffer 

front-end saturation from interfering signals thereby reducing sensitivity. 

• Accuracy: Marine radars are characterised by very short pulse-widths which 

improves resolution at the expense of occupied bandwidth. 

• Range: Another difference between aeronautical and maritime radar lies in the 

range of detection that is required. A typical maritime radar mounted 15 metres 

above sea-level on a vessel has a range of only 30 miles. Ground-based radars 

may have greater coverage but as they are tracking traffic at sea-level instead of 

airborne, the range is still much more restricted than their aeronautical 

counterparts. 

• Coverage: Additionally, as the area of interest for a ground-based maritime radar 

is out to sea, interference caused whilst it is sweeping inland areas is not a 

significant problem 13 . 

Primary maritime radars operate in the bands 2900 – 3100 MHz, 5460 – 5650 MHz and 

9200 – 9500 MHz. These radars are used in both the mobile role on board ship and in a 

fixed role for harbour and estuary control. The majority of fixed installations are in the 9 

GHz band and provide a high resolution display due to the short pulse-widths employed. 

Land based radars are used for a variety of shipping control and collision avoidance 

purposes as well as general surveillance by coast guards. Using computer processing 

and enhanced displays, the information derived from a group of these radars is displayed 

as an aid to collision avoidance. It also provides information for future traffic control 

systems. 

Peak rated powers for maritime radars range from 1 to 100 kW. Pulse lengths range from 

a maximum of 1.5µS down to 0.03µS for 3 GHz radars and 0.02µS for 9 GHz radars 

(implying 3dB bandwidths up to 50 MHz). Figure 4-1 below shows the current out-of-band 

emission mask for maritime radar (the same applies in all 3 bands, though note that it is a 

percentage based mask, hence the actual skirt of the mask is wider for the higher 

frequency bands). 

Maritime radars in the 3 GHz band typically operate on a centre frequency of 3040 MHz; 

radars in the 9 GHz band are centred around 9410 MHz. In the case of many lower cost 

radars, no mechanism of frequency feedback control is used such that the transmit 

frequency, once set at the point of manufacture or installation, may drift due to 

temperature and other conditions. 

Figure 4-1: Out-Of-Band Mask for Radars 

13 And indeed sector blanking can be used to turn off radar transmitters and receivers 

whilst they sweep areas of no interest. 

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Pulse compression techniques are already in use for some maritime radars. 

4.2.1.2 Operational Requirements 

No operational requirements relating to ground-based radar have been identified. IMO 

and other documentation regarding the performance of maritime radar relate only to its 

ship-borne use. 

4.2.1.3 Regulatory and Standardisation Issues 

Maritime radars are defined in technical standards produced by the ITU, IEC and ETSI, 

and their operational requirements in IMO documents. Table 4-1 below lists the relevant 

standards. 

Organisation Standard Description 

IEC 62252 Radar for craft not in compliance with IMO SOLAS Chapter V 

IEC 60872 Maritime navigation and radiocommunication equipment and 

systems – Radar plotting aids 


systems – Radar 


systems – General requirements 

IMO IB978E Performance Standards for Shipborne Radiocommunication and 

Navigational Equipment 

IMO IB970E Handbook on the Global Maritime Distress and Safety System 

ITU ITU-R M.1313 Technical characteristics of maritime radionavigation radars 

ITU ITU-R M.1314 Methods to reduce radar unwanted emissions 

Table 4- 1 Maritime Radar Standards 

4.2.1.4 Possible Improvements to existing technology 

A parallel Ofcom study “Techniques for improving radar spectrum utilization” is reviewing 

alternative technologies for radar. These technologies are likely to require extensive trials 

in the context of design and operational 

proving before adoption by maritime users. 

One interesting development is the sharing 

of radar information by Internet. Such a 

system would enable two (or more) suitably 

equipped users to share radar information. 

Whilst at the moment this technology is in its 

infancy, there is a clear potential to use, for 

example, wireless LAN connections to share 

radar information, improving accuracy and 

extending the range of current radars. In a 

sense, this is not strictly an improvement in 

spectral efficiency, it is simply a 

displacement of one service (radar) with 

another (wireless LAN or similar), nor would 

they negate the need for some radars to 

operate in the first instance. 

For GMDSS class vessels, such a system is 

unlikely to provide the degree of reliability 

that is necessary where safety-of-life issues 

MARITIME RADAR PLUGS INTO A PC 

German and Italian firms have joined forces to create 

a PC-based radar system that exploits the 

computer’s built-in networking capabilities to share 

information with other users over the Internet. 

Radars have traditionally been based on custom-built 

systems relying on proprietary hardware and 

software. This makes them expensive to build and 

maintain and difficult to connect to other 

manufacturers’ systems. The PC Radar board is 

based on off-the-shelf components and can be fitted 

inside a standard personal computer. It was 

developed by French electronics company Sodena 

under the Eureka EU research programme with the 

help of Italian firm GEM Elettronica 

In extreme circumstances when a ship loses the use 

of its own antenna, it could use PC Radar to look at 

another vessel’s image of local traffic on its own 

display. Fishing fleets, the yachting market and 

inland vessels will all benefit, the two firms say. 

http://www.eureka.be/pcradar/ 

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are a concern, however for smaller craft for which radar is a convenience rather than a 

necessity, such a system may well prove more cost effective than a full-blown radar. If an 

Internet connection back to shore can be established, safety of life services could also 

potentially view nearby vessels radar screens, assisting with the identification and 

location of ships in distress, or just generally enhancing their radar visibility in the area. 

4.2.1.5 Possible New Technologies (in-band) 

No new technologies being planned as alternatives to the current radar technology within 

the existing frequency allocation have been identified. Modern maritime radars already 

employ the majority of the standard techniques for improving accuracy and reducing 

output powers such as pulse compression. The move by the ITU to enforce tighter out-ofband 

emission limits will cause many of the older units installed to be replaced by more 

modern versions. 

4.2.1.6 Alternative Technologies or Spectrum (other or none) 

AIS 

The introduction of Automatic Identification System (AIS) provides an alternative 

mechanism for coastal stations to identify the location of vessels. The UK Coast Guard 

currently employs a network of AIS receivers around the UK rather than radars in order to 

locate shipping, it being a more cost effective solution than the large number of radars 

that would be required. AIS provides the additional function of identifying each ship. 

It is clear that many vessels are being fitted with AIS as a matter of routine thus there is a 

minimal economic impact concerned with implementing the standard. IPR issues with 

respect to AIS are addressed in section 6.10.4. 

4.2.1.7 Allocation Sharing Opportunities 

Sharing with other services 

The Maritime Coastguard Agency (MCA) informed us that they were not aware of any 

land-based maritime radars operating in the UK in the 5 GHz band. GMDSS requires that 

vessels of certain types install two radars operating in one or more of the 3, 5 and/or 9 

GHz bands, one (or more) of which must operate in the 9 GHz band. By far the most 

common usage is 3 and 9 GHz as these two bands, being of significantly different 

wavelengths compliment each other in terms of accuracy, resistance to weather 

conditions (fog, rain etc) and range. 5 GHz was seen as a possible compromise band but 

has been very little used other than; it is understood, in Japan and some parts of the 

USA. The MCA would not be concerned if this band were shared with or re-allocated for 

other users, as it would not expect there to be a knock-on impact for UK-based radar 

services. 

The band 5470 – 5725 MHz is under consideration as a potential band for HiperLAN 14 

(Band B – with a power limit of up to 1 Watt in the UK). This band clearly overlaps with 

the 5 GHz radar band at 5460 – 5650 MHz. Sharing is made possible in this context due 

to the low power, low range nature of the HiperLAN technology, and because of the use 

of Transmitter Power Control (TPC), which ensures that the minimum transmitter power 

required to maintain the connection is used, and Dynamic Frequency Selection (DFS) 

whereby channels found to be occupied (for example, by a radar or by another nearby 

14 All devices must comply with ERC Decision 99(23) and IR 2006 

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HiperLAN) are not used. ERC Report 015 deals with sharing between HiperLAN and 

radar operating at 5 GHz and concludes, 

“This report has studied the possibility of RLANs sharing with radar in the radiolocation 

bands around 5.5 GHz and has assessed the potential for interference from radar 

systems to RLANs. Using free space propagation formulae, the required separation 

distance between radars and RLANs is limited by the Radio Horizon (50 km for ground 

based radar and 340 km for airborne radar). However, this is the worse case and does 

not take into account terrain or building attenuation. Further calculations show that the 

RLAN could tolerate interference from between 5 and 14 radars at a given time. This is 

unlikely to reflect the majority of situations where RLANs will be used (mainly urban areas 

at some distance from radar installations), and the geographical distribution of interfering 

sources will probably be less than 5 radars within a radius of 50 km. Where an RLAN is 

operating within line of sight of one or more radars, the system throughput will be reduced 

but still within acceptable limits.” 

There are also a number of assignments to Programme Making and Special Events 

(PMSE) in the range 5480 – 5815 MHz. These are used for temporary point-to-point video 

links as well as radio cameras and portable video links. PMSE transmissions in this band 

have a maximum ERP of 40dBW and, where the allocation overlaps with the maritime 

radionavigation band, the frequencies must not be used within 10km of the coast. The 

fact that these allocations are licensed and co-ordinated means that protection of 

maritime services can be, so far as possible, ensured. 

ERO Report 006 investigated the potential for sharing between PMSE and radar services 

in the frequency band 2700 – 2900 MHz; whilst this is an aeronautical radar band the 

findings are, nonetheless, relevant. Fundamentally, the report argues that the coordination 

distances between aeronautical radar and PMSE video links was such that it 

would require international co-ordination in most cases, and thus be time-consuming. The 

report’s overall conclusion was that it would not be possible to share between 

(aeronautical) radar and PMSE. 

A paper by SE34 considering measures of spectral efficiency for radars (SE34(01)35) 

concludes: 

“In describing the ways in which radars occupy parts of the spectrum in bandwidth, 

time, space and polarization, the opportunities of sharing have been mentioned. 

This paper started with a statement that radars do not easily share with other 

services. As has been shown there are some limited opportunities for radars to 

share with other radars. These cases do not extend to sharing with other services 

within the coverage area of the radar except in special circumstances. In general it 

is concluded again that radars do not share their spectrum easily” 

The key here is that radars do not share well within the coverage area of the radar. With 

maritime radar being focussed around the coastline, there are still potential sharing 

opportunities inland. 

Reduction in available spectrum 

In discussions with radar users, it would appear that there is not yet strong evidence of 

congestion in the radar bands at present (even in busy shipping lanes such as the English 

Channel). Such congestion would appear as numerous unidentified dots on the radar 

display. The systems employed by maritime radar systems to block interference from 

other radars clearly enable a good degree of sharing. 

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Though the amount of shipping traffic is still growing, this growth is relatively small 15 ; it is 

unlikely that in the short- to medium-term congestion in the maritime radar bands will be 

experienced. One option is therefore to reduce the amount of spectrum available to 

maritime radars and re-use the recovered spectrum for other purposes. 

However, the ability to restrict the spectrum allocated to maritime radars is, to a large 

extent, hamstrung by the international nature of the traffic. Whilst the UK could impose, 

for example, a restriction on the available radar spectrum, it would be very difficult for 

radar users entering UK waters to comply with this. Notwithstanding this, there are also 

issues with some of the transponders that are used to enhance the visibility of certain 

geographical features (as described in the following sections). A unilateral decision by the 

UK to reduce available spectrum could, however, significantly reduce the number of radar 

emissions in a given part of the spectrum to a degree where it may become possible for 

other services to use the spectrum successfully. 

Combined with a drive to improve sharing between services, allowing sharing in some of 

the spectrum whilst making it clear that that particular portion of a band was not to be 

used by UK vessels may offer the best solution for making more effective use of the 

spectrum. 

4.2.1.8 Possible Overall Spectrum Efficiency Improvements 

The operational restrictions placed on maritime radar mean that changes to the 

specifications are unlikely to yield a significant improvement in spectral efficiency. 

However there does appear to be some potential for a reduction in the amount of 

spectrum allocated to maritime radar services, especially if this sharing is confined to one 

portion of the band. 

4.2.2 RACONs 


Radar Beacons (RACONs), when used with a ship’s radar form a secondary navigation 

system and operate in the 3 and 9 GHz bands. 

ITU Radio Regulation 4.40 defines a RACON as: ‘a transmitter receiver device associated 

with a fixed navigational mark which, when triggered by a radar, automatically returns a 

distinctive signal which can appear on the display of the triggering radar, providing range, 

bearing and identification information.’ 

The displayed response has a length on the radar display corresponding to a few nautical 

miles, encoded as a Morse character beginning with a dash for identification. The 

inherent delay in the RACON causes the displayed response to appear behind the echo 

from the structure on which the racon is mounted. 

Racons are used for the following purposes: 

• To identify aids to navigation, both seaborne (e.g. buoys) and land-based (e.g. 

lighthouses); 

• To identify landfall or positions on inconspicuous coastlines; 

• To indicate navigable spans under bridges; 

15 

UK international freight for example grew on average just 2.3% per annum between 

1980 and 2000 

Page 131

• To identify offshore oil platforms and similar structures; 

• To identify and warn of environmentally-sensitive areas (such as coral reefs); 

• To mark new and uncharted hazards; 

• To identify centre and turning points. 

RACON range is approximately line-of-sight range, normally over 15 nautical miles, 

although actual range depends upon a number of factors, including mounting height, 

atmospheric conditions, and racon receiver sensitivity setting. 

RACONs can be placed on any navigational mark (lighthouses, beacons, perches, buoys, 

etc). The return on the ship’s radar will clearly identify the mark from surrounding targets 

and allow the mariner to accurately measure his range and bearing. 


There are approximately 1,000 racons in operation in and around the UK. 


The ITU-R Recommendation M.824-2, Technical Parameters for Radar Beacons 

(RACONs) specifies the minimum technical characteristics for general purpose RACONs 

and contains guidance for their use. 

A recommended specification for RACONs is published (reference R-101r1) by the 

International Association of Maritime Aids to Navigation and Lighthouse Authorities 

(IALA). 


The IMO sub-committee on safety of navigation in a report on a review of performance 

standards for radar equipment 16 states that: 

“It is perceived that the requirement to trigger SARTs and RACONs of current designs 

imposes constraints on radar design. These constraints, when coupled with future ITU 

requirements to restrict out of band emissions, may result in increased costs and 

complexity of equipment. Whilst compatibility with SARTs 17 at X-band must remain until a 

replacement beacon is mandated by IMO, it is considered that the requirement to operate 

RACONs at S-band can be removed from the mandatory performance requirements and 

thus allow innovative design of radar operating in this band.” 

It is clear, therefore, that the maritime community appreciates the need to improve the 

performance and spectral efficiency of maritime radars and the proposed removal of the 

need to support RACONs in S-Band would enable new technologies to be employed. 

Implementing this recommendation is unlikely to have a major financial or operational 

impact on the maritime industry. RACONs currently operate in both bands, and most 

organisations who implement them provide RACONs in both S- and X-bands. As X-band 

is the most common form of radar (and indeed at least one radar on a GMDSS compliant 

vessel must work in X-band) the removal of S-band RACONs would appear to be a logical 

step forward to allow the development of more efficient maritime radars in S-band. 

16 

Reference: NAV49/9 

17 

SARTs do not operate on S-Band frequencies 

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No new or replacement technologies which operate in the same bands have been 

identified. 


No alternative technologies have been identified. 


There are no sharing opportunities specific to RACONs as they occupy the same 

spectrum as their interrogating radars. As such, sharing with radars will, by default, imply 

sharing with RACONs. 


The removal of the necessity for RACONs to operate in both S- and X-bands in favour of 

an X-band only system would allow more efficient maritime radars to be developed in Sband. 

4.2.3 SHF 14 GHz Ship Berthing 

4.2.3.1 Frequency Allocations (International & National) 

There is no specific spectrum allocation to Maritime Radionavigation in this frequency 

band; however the frequencies 13.4 – 14.0 GHz are allocated both in Region 1 and in the 

UK to both Radionavigation and Radiolocation as co-primary services. Further the 

frequencies 14.0 – 14.3 GHz are also allocated both at Region 1 and in the UK to 

Radionavigation as a primary service. 


Ship-berthing radars are Doppler radars mounted on jetties etc, to assist the berthing of 

very large ships. A search of the Internet suggests that such devices operate on various 

frequencies in Europe, examples being 12.6 GHz, 13.2 GHz and the frequency band 13.7 

– 14.3 GHz. They are used mainly to dock very large oil tankers at a few specific 

locations. Such vessels have enormous potential for damage even at extremely low 

speeds. Although ship-berthing radars are low power devices and few in number, they are 

significant in terms of safety and possible environmental consequences of an accident. 


We have not yet managed to identify any hard evidence that these systems are in use in 

the UK, however it is known that standard maritime radar does not have sufficient 

accuracy to allow some larger vessels to successfully dock at some of the more active 

ports in the UK and that devices such as ship-berthing radars provide the additional 

information necessary to ensure the successful management of larger vessels. 


There do not appear to be any internationally mandated standards for ship-berthing radar, 

however it seems likely that such devices are in fact short range Doppler devices as 

specified in CEPT/ERC/DEC (99)07 and ETSI EN 300 440. As such they operate at lower 

powers of 25mW and are licence exempt in the UK as long as they operate between 13.4 

and 14.0 GHz. 

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None identified. 






The frequencies on which ship-berthing radars operate are already shared with other 

services. The UK frequency allocation table covering the main frequencies over which it is 

believed such devices operate is reproduced below: 

13.75 – 14.00 GHz 

FIXED-SATELLITE (Earth to space) UK5 

RADIOLOCATION 

RADIONAVIGATION UK130 

Standard Frequency and Time 

Signal- Satellite (Earth to space) 

Space Research 

5.501, 5.502, 5.503, 5.503A 

UK4, 11 

14.0 – 14.25 GHz 

FIXED-SATELLITE (Earth to space) 

5.484A, 5.506 UK1, 5 

RADIONAVIGATION 5.504 

Land Mobile-Satellite (Earth to space) UK1, 5 

UK4 13.4-14.0 GHz – MoD 

UK5 13.75-14.00 GHz – DTI – For the 

Fixed-Satellite Service 

UK130 The radionavigation service is 

limited to 13.7-14.0 GHz and to 

assignments agreed by MoD 

UK5 14.0 – 14.4 GHz – DTI (for the 

satellite and land mobile-satellite 

Services); 

14.25 – 14.4 DTI (for the fixed and 

mobile except the aeronautical 

mobile services). 

fixed 

Table 4- 2 UK Frequency Table 13.75 – 14.25 GHz 

No strong evidence is available to suggest the use of ship-berthing radars in this band 

other than the Norwegian Frequency Allocation Table which lists ‘Ship Berthing Radar’ in 

the range 13.25 to 13.75 GHz. It therefore seems wholly possible that such low power, 

low range radars are operating in various ports around the UK without causing 

interference to other spectrum users. Nonetheless, there is a need to bring such radio 

usage under licence control. 


If radio spectrum is being used for these services, quite possibly without the users 

realising that such usage is not licensed, there is potential for them to cause interference 

to other radio users. 

Page 134


Ofcom should initiate a market survey to determine the extent of usage of such 

equipment and identify potential frequencies that could be used in the UK, if such are 

available and required, in order to bring the usage of such equipment into a licensed 

framework. 

4.3 Shipborne 

4.3.1 MSR (Maritime Surveillance Radar) 


The description given in section 4.2.1.1 concerning ground-based radars applies equally 

here and has not been duplicated for the purpose of brevity. 

The requirements for ship-borne radars vary; many vessels are required by the IMO 

convention on safety of life at sea to carry two radars. This requirement can be met by 

fitting two 9 GHz radars or one 9 GHz radar and one either 3 GHz or 5 GHz radar. The 

band 9200 – 9500 MHz is by far the most commonly employed, but the 3 GHz band is 

used on ships which encounter sleet and snow on a regular basis, as it gives better 

results in these conditions due to a reduction in the effects of clutter relative to the 9 GHz 

band. A low-power version of the 9 GHz radar is fitted to a large number of yachts and 

pleasure vessels. 


IMO Operational Requirements 

The IMO sets out the operational performance criteria which maritime radars shall meet. 

This standard sets limits for accuracy of measurement and minimum and maximum range 

over which the radar must produce the specified level of accuracy. 

The practical implication of the range requirement translates into the need to mount the 

radar head at least 15 metres above sea level. It is common practise, however that the 

electronics associated with the radar (including the RF modules) are on the deck. This 

has a direct impact on the technical specifications of the radar. The short delay in sending 

the transmitted signal up 15 metres of cable, and waiting the same time for the received 

reflections, together with the speed at which it is possible to switch between transmit and 

receive, plus the minimum range requirement (i.e. how close to a vessel the radar must 

function) of 40 metres has a direct impact on the pulse-width, which must remain short in 

order to meet the IMO operational requirements. Keeping the pulse short implies a wider 

bandwidth. 

GMDSS Requirements 

The Global Maritime Distress and Safety System (GMDSS) is a maritime communication 

system for all vessels. However, it is not just for emergencies and can be used for vesselto-vessel 

routine communications. Commercial vessels over 300 gross tonnage and 

certain smaller fishing vessels, including some fishing boats are mandated to carry 

GMDSS equipment. Most of the well-known offshore yacht races now insist yachts are 

GMDSS equipped too. The GMDSS requirements split the oceans into 4 different kinds of 

area, each dependent on distance from the shore, and density of maritime traffic. The sea 

area a vessel is to operate in, determines which of the elements of the GMDSS that it 

must carry. 

There are several elements that make up the total GMDSS communications package 

including Digital Selective Calling (DSC) via radio. The other elements include satellite 

communications, Navtex for weather and navigation information, Search and Rescue 

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Radar Transponders (SARTs) and Emergency Position Indicating Radio Beacons 

(EPIRBs). 

Ships built on or after 1 February 1995 have been required to be fitted with all applicable 

GMDSS equipment. Ships built before that date were given until 1 February 1999 to 

comply fully with all the GMDSS requirements. 


See section 4.2.1.3 


See section 4.2.1.5. 


AIS 

The introduction of Automatic Identification System (AIS) provides an alternative 

mechanism for coastal stations to identify the location of vessels. The UK Coast Guard 

currently employs a network of AIS receivers around the UK rather than radars in order to 

locate shipping, it being a more cost effective solution than the large number of radars 

that would be required. AIS provides the additional function that it identifies each ship. 


It is clear that many vessels are being fitted with AIS as a matter of routine thus there is a 

minimal economic impact concerned with implementing the standard. 


The Maritime Coastguard Agency (MCA) informed us that they were not aware of any 

land-based maritime radars operating in the UK in the 5 GHz band. GMDSS requires 

radars operating at 3, 5 and/or 9 GHz but the most common usage is 3 and 9 GHz as 

these two bands, being of significantly different wavelengths compliment each other in 

terms of accuracy, resistance to weather conditions (fog, rain etc) and range. 5 GHz was 

seen as a possible compromise band but has been very little used other than; it is 

understood, in Japan and some parts of the USA. The MCA would not be concerned if 

this band were shared with or re-allocated for other users, as it would not expect there to 

be a knock-on impact for UK-based radar services. 

Please see section 4.2.1.7 


Please see section 4.2.1.8. 

4.3.2 SHF 9 GHz SARTs 


A Search and Rescue Transponder (SART) is a device which is used to locate survival 

craft or distressed vessels by creating a series of dots on a 

rescuing ship’s radar display. SARTs only operate with X-Band 

(9 GHz) radar systems. 

A SART is triggered by any 9 GHz radar within a range of 

approximately 8 nautical miles. Each radar pulse received 

causes it to transmit a response which is swept repetitively 

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across the complete radar frequency band (9200 – 9500 MHz). At some point in each 

sweep, the SART frequency will match that of the interrogating radar and be within the 

pass-band of the radar receiver. If the SART is within range, the frequency match will 

produce a response on the radar display (typically a line of 12 dots or arcs equally spaced 

by about 0.64 nautical miles out from the SART’s location). 


SARTs form part of the GMDSS (which applies to cargo ships of 300 gross tons and over 

when travelling on international voyages or in the open sea and all passenger ships 

carrying more than twelve passengers when travelling on international voyages or in the 

open sea), and SARTs are mandatory in any of the GMDSS sea areas. 


SARTs are standardised by the IEC in document IEC 61097-1 (Global maritime distress 

and safety system (GMDSS) – Part 1: Radar transponder – Marine search and rescue 

(SART) – Operational and performance requirements, methods of testing and required 

test results). ETSI standard ETS 300-151 (Radio Equipment and Systems (RES); 9 GHz 

radar transponders for use in search and rescue operations Technical characteristics and 

methods of measurement) also applied but has since been withdrawn. 


9 GHz SARTs are mandated by GMDSS. Unless there is a change in the requirement, it 

is highly unlikely that the UK could take a unilateral decision to modify the specification or 

otherwise employ alternative technologies. SARTs form part of the key safety-of-life backstop 

for vessels in distress. 


There are no developments planned to the existing SART specifications. 


No new technologies have been identified. 


No alternative technologies have been identified. 


No sharing opportunities specific to SARTs have been identified. 


It is worth noting that any move to reduce the amount of spectrum available to maritime 

radars in the 9 GHz band for re-use by other services could be hampered by the 

presence of SARTs. The SART response to interrogation, i.e. to emit a signal that sweeps 

across the whole radar band (thereby ensuring that it is detected by the interrogating 

radar – and any others nearby) means that if the allocation to maritime radar in the 9 GHz 

band were to be reduced, any existing SARTs, when triggered would emit a signal across 

the whole of the current band, ignoring the reduction in allocation. 

That being said, SART usage is for emergencies only, and hence the level of interference 

caused by the SART would be very limited. They are also most often used at sea, further 

reducing the potential for interference into the UK. As the SART would still be sweeping 

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the whole of the reduced band, the effectiveness of the SART in causing detection on 

nearby radars would not be impaired. 

4.3.3 Radar Target Enhancers (RTEs) 

4.3.3.1 Technology description 

A Radar Target Enhancer (RTE) is designed to respond to an interrogating radar with an 

amplified signal, which is transmitted on the same frequency with minimal time delay in an 

omni-directional manner. The effect of this is to provide the structure on which it is 

mounted with a consistent radar return where otherwise, without enhancement, it would 

have become intermittent, difficult or impossible to detect. 


IMO Regulation 19 paragraph .2.1.7 requires radar reflectors or other means to enable 

detection by ships navigating by radar at both 3 and 9 GHz to be carried, where 

practicable, by ships less than 150 Gross Tonnes. For UK-flagged this includes pleasure 

vessels. Under this regulation, RTEs are regarded as ‘other means’. 


Reflectors meeting the standards laid down in British Standard BS 7380:1990 (ISO 

standard 8729: 1987) meet IMO performance standards. Radar reflectors which were 

type tested and approved to the earlier Department for Transport (DfT) Marine Radar 

Reflector Specification, published in 1977, also comply with the IMO standards. 

Recommendation ITU-R M.1176 gives the technical parameters for RTEs. 


Though not strictly an improvement, RTE’s only respond on the frequency on which they 

are interrogated. It is therefore possible that changes could be made to the frequencies 

allocated to the interrogating radar such that the response of the RTE was also modified. 


Older technologies such as passive radar reflectors are still in use on some vessels, 

where there is sufficient space (RTEs providing a similar reflection in much less physical 

space). RTEs are currently required to operate in both the 3 and 9 GHz bands (but not 

the 5 GHz band), however there is a clear move by the maritime community to 

considering the 9 GHz band as the mandatory requirement, with 3 GHz as a back up and 

where required by vessels that encounter diverse environmental and weather situations. It 

may thus be possible, to remove the requirement for RTEs to operate at 3 GHz (as has 

been suggested for RACONs). 




No sharing opportunities specific to RTEs have been identified. 

Page 138


As with many of the ship-borne devices employed to assist visibility of objects, it is 

changes in the specification of the interrogating radar that would bring about the greatest 

potential efficiency gains, and not the transponders such as RTEs. 

4.4 Conclusions and Recommendations 

Though opportunities improving the spectral efficiency of the radar and associated 

technologies used for maritime radiodetermination are limited, there are potential 

modifications to spectrum use which could make overall more efficient use of spectrum. 

Recommendation 4.1: The 5 GHz band is little used by (commercial) maritime radar in 

and around the UK. It is already shared with PMSE and HiperLAN. Further sharing of this 

spectrum with other, suitably compatible services should be investigated. 

The fact that the existing 5 GHz maritime radar band is already successfully shared with 

other compatible services implies that further sharing opportunities may exist. 

Socio-Economic Issues 

It is our understanding that few, if any, UK vessels are fitted with 5 GHz radar equipment. 

Thus, the impact to the UK shipping community of the removal of (all or part of) this band 

or increased sharing would be minimal both in terms of cost to the industry and in terms 

of operational impact. However, there may still be occasions when non-UK registered 

vessels which do use 5 GHz radars enter UK waters. This would have 2 potentially large 

impacts: 

UK services using the 5 GHz band may be impacted by the transmissions from the 

radars. This is most likely to occur in coastal areas and the impact would depend, to a 

large extent, on the technology chosen to operate in the band. For example, the existing 

HiperLAN specifications take specific account of the presence of radars. Similar sharing 

criteria 18 may need to be considered if the band is to be used for permanent (e.g. 

operating 24 hours x 7 days) services. 

The radars on the affected vessels will suffer interference. Unless the vessels are fitted 

with ONLY a 5 GHz radar, which is unlikely if they are covered by GMDSS rules, as at 

least one on-board radar must be in the 9 GHz band, and then interference to the radar 

would not cause an operational problem. The situation is further improved by the fact that 

the interference would occur when the radar was sweeping across the UK landmass, and 

not whilst out to sea. Of course, this would hamper detection of other vessels between the 

vessel and the coast but as the 9 GHz radars would continue to function, the overall loss 

of visibility would be minimal. 

Regulatory Impact 

Increased sharing of the 5 GHz band with other services would not require a change to 

any standard or specification relating to maritime radar equipment, as no change to the 

radars themselves would be required. 

The next step would be for Ofcom to determine appropriate sharing criteria for the band. 

Such a determination will involve consideration of the role of the other services already 

sharing the band and may show that further sharing is not practical. If such an 

investigation did, however, prove the possibility of additional sharing, Ofcom may also 

wish to consider giving notice that it intends to open the band for further sharing in order 

18 Such as the use of Reed-Solomon or BCH codes 

Page 139

that UK registered vessels can take appropriate decisions about the band in which they 

purchase any new equipment. 


The use of incentive pricing is only applicable where users are required to change 

behaviour. In this instance, existing users would not be expected to change behaviour, 

instead additional users occupy the same spectrum and thus the application of AIP in this 

context is not suitable. 

Recommendation 4.2: Consider a reduction in the allocations to maritime radar at 3, 5 

and 9 GHz. Such a reduction would require a study into congestion levels in the three 

bands. 

The fact that there is little evidence of congestion in the maritime radar bands, and that 

the growth in maritime traffic remains relatively modest (around 2.3% per annum) 

suggests that there is scope to reduce the amount of spectrum allocated to such services. 

To what extent such a reduction may be feasible and how much spectrum may be 

recovered will depend upon the impact of the reduction on the level of congestion in the 

affected band, and the impact of that congestion on the operation and detection of other 

vessels and hence safety. A detailed analysis of the current level of traffic in the most 

congested areas (the English Channel and the Solent) would be needed in order to give 

an indication of current congestion levels. 


To some extent the spectrum recovered by any reduction in the allocation would not be 

completely clear. The use of radars on a wide range of international shipping traffic that 

enters UK waters, would mean that it would be impossible to stop some radars working 

on the recovered frequencies, however UK registered vessels could be made to empty a 

specific section of one or more of the bands. Another factor in the potential success of 

any such reduction would therefore be the extent to which the maritime traffic in and 

around the UK comprises UK registered vessels as opposed to those registered (and 

hence licensed, for radio purposes, elsewhere). 

In the 9 GHz band, the situation is further complicated by the use of SARTs. Once a 

SART detects an interrogating radar it responds by sweeping a signal across the whole 

available band (9200 – 9500 MHz) to ensure that it is detected, not just by the 

interrogating radar, but also by any others which may be in the vicinity. SARTs are 

required by GMDSS but are only activated when a vessel is in distress. However whilst 

an activated SART would transmit a signal across the whole 9 GHz band, thereby having 

the potential to cause interference to other users who may be occupying any cleared 

spectrum, in practise, this is unlikely to be a major issue. 

Firstly, SARTs are only triggered in emergency situations where the situation has not 

been identified by other means (such as visual sighting), thus the amount of interference 

they are likely to cause is very small. 

Secondly, such emergencies are more likely to occur away from highly populated 

coastlines (as events taking place along more populated coastlines would be more likely 

to be seen by other methods such as visual sighting or other radars). Thus the level of 

interference to any on-shore communications would be relatively small. 

Thirdly, the visibility of a SART would not be affected by a reduction in frequency 

allocation. Whilst it would sweep across frequencies that may have been re-allocated for 

other services, it would also, by nature of its design, sweep across the frequencies still 

being employed by radars. Thus the effectiveness of a SART would not be diminished by 

a reduction in allocated spectrum. 

Other devices such as RACONs and RTEs, generally respond on the frequencies on 

which they have been interrogated. Interrogation by a radar which is operating in a 

Page 140

educed frequency allocation would therefore result in a response within that allocation. 

However, if non UK licensed vessels were to interrogate the device on a frequency 

outside any reduced allocation, it would have to respond on the interrogating frequency, 

otherwise its function would be impaired and it would not show up on the radar. If the 

device (in particular an RTE) were mounted on a vessel out at sea, this is unlikely to be a 

problem to any other users of the spectrum as the range of such devices is limited. For a 

RACON mounted on a coastal feature, the main direction of the responding beam would 

be out to sea, and hence the amount of interference caused inland would be minimal. 

From a technical and social perspective, it therefore seems highly possible to reduce the 

amount of spectrum available to maritime radars with minimal impact. Such a reduction 

could not be achieved using many of the current systems employed which are, due to the 

low cost nature of their construction, struggling even to fit with the existing ITU mask. 

However, the use of more modern techniques would allow better frequency control and 

thus a reduction in the required bandwidth. 

From an economic standpoint, radars are typically replaced every 8 to 10 years, meaning 

that it can take up to 25 years overall before old technologies are fully phased out. 

However a reduction in spectrum does not require new technologies to be installed 

(though operators may take the opportunity to do so if other changes take place). Instead, 

some radars would require re-tuning away from the frequencies which were being 

reassigned for other uses. The proportion of radars so affected would depend on how 

much of the frequency were re-allocated. The financial impact would also be less than a 

complete change-out of technology. A new maritime (ship-borne) radar typically costs 

between £1000 and £10000 depending on the level of sophistication (the lower range of 

prices applies only to small radars intended for small ships and pleasure craft). Thus, it is 

reasonable to assume that re-tuning a radar would not cost, on average, more than 

£2500, and even this amount would seem relatively large. 

The 3 GHz band (2900 – 3100 MHz) is currently 200 MHz wide. The typical 3dB emitted 

bandwidth of maritime radar is up to 50 MHz. Assuming this as a worst case, reducing the 

amount of spectrum by 50 MHz (25%) would appear reasonable. The number of ships 

registered (and hence licensed) in the UK (including the Isle of Man which is also covered 

by UK maritime licensing) is estimated to be 11,000 19 . Thus a reasonable estimate of the 

cost of retrieval of 50 MHz of spectrum, assuming that some modifications were required 

to all vessels operating in the 3 GHz band is £23 million. The actual figure for the 3 GHz 

band is likely to be lower than this as it is less common in use than the 9 GHz band (for 

which more than one radar may be fitted to any given vessel). 

A similar proportion of the 9 GHz band (being wider at 300 MHz wide) would return 75 

MHz for similar costs. The cost at 9 GHz is likely to be higher as it is a more popular 

frequency range, however as the centre frequency most commonly employed is 9410 

MHz, which is towards the top of the 300 MHz wide allocation, it may well be relatively 

straightforward to recover spectrum at the lower end of the band, where fewer radars are 

operating. 

However, maritime radars are not the only users of the bands allocated to maritime radar. 

All are shared with military users (and in the case of the 3 GHz band, with aeronautical 

radars). Whilst it may be possible for maritime users to change their use of spectrum, the 

19 The Isle of Man has 9,000 registered vessels. Data for the UK, not being in the top 20 

countries for which data is published, is unknown but must be less than 8,000 (the 

number registered to the country in 20 th place). Being a relatively major maritime nation 

we have therefore assumed that the UK has 2,000 registered vessels making a total of 

11,000. 

Page 141

other occupiers of the spectrum could easily stymie any reduction in the allocation and 

consideration needs to be taken of the systems employed by other users before it would 

be worthwhile to make any changes to maritime radar users. 

Regulatory Impact 

The reduction in allocation to maritime radar in any of the currently used bands would 

have a direct impact upon the specifications of the radars deployed. Many current radars, 

though nominally operating on frequencies slightly offset from the centre of the bands, 

due to the short pulse-widths and the limitations in frequency control, in effect occupy the 

whole of the available band. However, technically there is no need for them to do so. The 

application of more modern techniques could reduce the overall bandwidth required. Such 

a change would therefore require maritime radars sold in the UK to conform to a UK 

specific specification. 

To achieve this may be a challenge itself. UK vessels subject to IMO Carriage 

Requirements are required to comply with the EU Council Directive on Marine Equipment, 

98/85/EC and modifications. In accordance with the provisions of this Directive, radio 

equipment installed on board a vessel required to comply with SOLAS, must install 

equipment that complies with the standards of those Standardisation Bodies listed in the 

relevant Annex to the Directive. This requires that such equipment must comply with 

either the relevant ETSI Standard or the International Electro-Technical Commission 

(IEC) Standard. The equipment would also have to be marked as compliant with the 

standard. However Article 6.1 of the Directive states, ”No Member State shall prohibit the 

placing on the market or the placing on board a Community ship of equipment referred to 

in Annex A.1 which bears the mark or for other reasons complies with this Directive or 

refuse to issue or renew the safety certificates relating thereto.” 

These requirements would continue (unless the Directive and IMO Carriage 

Requirements were amended) even if the UK introduced a requirement for more 

spectrally efficient equipment to be installed on UK vessels since a vessel owner could 

still fit any equipment bearing the ships wheel mark. However AIP might be applied to 

encourage purchase of equipment which met a UK ‘voluntary national measure’ which 

encouraged spectrally efficiency whilst maintaining operational integrity. 

A similar situation could arise with non SOLAS vessels where radar equipment is subject 

to the R&TTE Directive, 99/5/EC. This ‘new approach Directive’ relies on the use of 

harmonised standards (developed as a result of a Commission mandate to CEN, 

CENELEC and/or ETSI) to provide a presumption of conformity with the essential 

requirements of the Directive, one of which (Article 3.2) requires the effective and efficient 

use of the radio spectrum to avoid harmful interference. 

Within the R&TTE Directive the concept of harmonised frequency bands has been 

introduced. Every frequency band can be considered harmonised throughout the EU if it 

satisfies the following: 

• it is designated to accommodate radio equipment which can only transmit under 

the control of a network; or 

• it is allocated to the same radio interface in every Member State in the following 

way: 

o there is a common frequency allocation; and 

o within this allocation, the allotment and/or assignment of radio 

frequencies or radio frequency channels follows a common plan or 

arrangement; and 

o the equipment satisfies common parameters (e.g. frequency, power, 

duty cycle, bandwidth, etc.) 

Page 142

A non harmonised frequency band is considered to be the complement of a harmonised 

band. Information on whether a band is harmonised or not is expected to be included in 

national frequency tables. The R&TTE Directive imposes the obligation on EU Member 

States to publish their National Frequency Plans. Where bands are harmonised, the 

Commission will identify those and include them in the group of interfaces for Class 1 

bands. This list is maintained in consultation with the Member States and published on 

the Web. 

In non harmonised frequency bands such as the radiodetermination bands, a 

manufacturer is required to notify an administration before placing the equipment on the 

market. Administrations in turn issue ‘interface requirements’ with any specific national 

requirements. It could be argued that if spectrally efficient requirements were introduced 

by the UK to avoid harmful interference to current and future services then this would be 

in accordance with the Directive. On the other hand difficulties might arise if UK 

requirements were such that CE marked or IEC compliant equipment designed for the 

band in question and accepted by other Member States were not acceptable in the UK. 

Again the UK interface requirement or a licence condition might include a ‘voluntary 

national measure’ where R&TTE compliant equipment, which met more strenuous 

spectral efficiency targets, could receive favourable fees treatment under an AIP regime. 

Of course in both SOLAS and non SOLAS cases proportionality would be the key to 

achieving favourable treatment by the Commission and other Member States. It might 

also be advisable to discuss ‘voluntary national measures’ with the Commission before 

introducing such concepts. 

The application of Pricing 

Pricing could be used to modify the behaviour of the maritime user in this instance. The 

cost of replacing a radar with a newer version such as would be required in order to 

reduce the emitted bandwidth could be encouraged by the application of AIP to the 

appropriate element of the maritime radio licence. The magnitude of the likely cost of 

modifications to each radio user (i.e. circa £2,500) is such that appropriate licence costing 

could have an impact on users’ behaviour. 

Recommendation 4.3: Introduce additional sharing, in particular with PMSE in the 3 and 

9 GHz maritime bands. 

An alternative to reducing the amount of spectrum allocated to maritime radars would be 

to increase the amount of sharing with other services. As has been shown in the 5 GHz 

band, sharing of maritime radars with other, compatible services, can take place. 

However an ITU study into possible sharing with aeronautical radar determined that 

sharing with any service was not practicable. The largest issue concerning increased 

sharing is that of the impact of the interference from the sharers into radars. A small 

increase in the background noise yields a significant reduction in the range and potential 

accuracy of a radar. The 9 GHz band is obviously the most sensitive to such effects as 

devices such as SARTs are used for safety of life purposes. 

Nonetheless, the opportunity for increased sharing in the 3 and 9 GHz bands with 

maritime radar services appears feasible. As with the comments under option (1), this 

position is aided due to the nature of maritime radar services. 


In principle, carefully selected sharing between maritime radars and other users should 

have minimal or little impact on the maritime users, either operationally or financially. It is 

therefore difficult to quantify the economic effects of such sharing. Only in the event that 

such sharing required modernisation of existing radars would there be a financial impact, 

insofar as the need to modify existing radars. 

Page 143

Given the physical range of transmissions in the bands concerned, it is also feasible that 

the UK could ‘go it alone’ in making changes to these bands as only in exceptional 

circumstances would any interference be caused to or from foreign countries. 

However, and especially in the 9 GHz bands, the operation of radars and their associated 

devices (RTE, RACON etc) are a large and critical part of the services which protect the 

lives of mariners. If the UK were to introduce services which were, at a later date, proven 

to have caused an incident involving loss of life, the social consequences could be 

potentially large. However, radars are not the only element of the GMDSS, which also 

includes EPIRBs relying on satellite communications. Having said that, identifying the 

location of a vessel at sea can not easily be accomplished by satellite and EPIRBs, but at 

sea is unlikely to be where land-based interference is a large problem. 

The major restriction in terms of increased sharing is however, the other users who 

occupy the bands. The 3 GHz band is already shared with aeronautical services and both 

the 3 and 9 GHz bands are shared with military users. It seems likely, therefore, that 

sharing of the maritime radar bands with other users, despite the apparent feasibility of 

such sharing, is again stymied by those other users. 

Recommendation 4.4: A survey into the usage of ship-berthing radar should be 

conducted and a suitable allocation (if available and required) made available to enable 

them to be licensed. The potential for these (or indeed any other) unlicensed devices, to 

cause interference to legitimate spectrum users needs to be controlled and Ofcom should 

consider undertaking a market surveillance exercise to determine the size and nature of 

the problem. 

The unlicensed use of ship-berthing radars at around 14 GHz had the potential to cause 

interference with other licensed users. It is possible that such radars are lower power 

devices operating in licence exempt spectrum under the auspices of ERC decision 

99(07). However, this has not been proven. 

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5 Aeronautical Communications 

Civil aviation provides a major source of transport for passengers, and for high-cost low 

volume or perishable goods. For business travel air is the only viable means for journeys 

exceeding 1000 km. The air transport regime is a highly competitive one, with pressures 

increasing for greater efficiency and flexibility of operation. The market and the players 

are global, margins are minimal, and mistakes are often costly and disastrous. On a 

broader front an efficient air transport system is a vital determinant in the economic 

prosperity and the exploitation of the resources of countries and of regions, generating 

some £108 billion per annum of economic activity within the European Union. Future 

estimates of aviation activity and knowledge of future plans are a pre-requisite to the 

assessment for radio frequency spectrum. This chapter examines some of the key issues 

concerning aeronautical radiocommunications. 


Aeronautical communication is an essential safety critical service providing a constant link 

between pilots and controllers. Communication is also important for commercial data 

related to airline operations and, increasingly, to the provision of services for passengers. 

Aeronautical communication requirements are generally considered under the following 

headings: 

• Air Traffic Services (ATS): services to support air traffic control including direct 

communication between controllers and pilots. 

• Airline Operational Control (AOC): services involving data transfer between the 

aircraft and the Airline Operational Centre or operational staff at the airport 

associated with the safety and regularity of flights. The Airline Communications 

Addressing and Reporting System (ACARS) has supported this service since the 

1980s. This is considered to be a growth area and airlines are expected to start 

making increased use of datalink applications to provide communications at the 

gate and airborne monitoring applications. 

• Airline Administrative Communications (AAC): includes applications concerned 

with administrative aspects of airline business such as crew rostering and cabin 

provisioning. These are essential to the airlines business but do not impact on 

the safety and regularity of flight. AAC applications are not specified by ICAO 

and should not use communications resources reserved for safety 

communications. 

• Airline Passenger Correspondence (APC): includes communications services 

that are offered to passengers (email, internet access and telephony). Access to 

such services would be via seatback screens, airline provided equipment or 

passengers own laptops or other mobile equipment. Services would be offered to 

passengers within the ticket price or as a chargeable service. 

For air traffic services, the existing technology is extremely simple, based in terrestrial 

regions on voice communication over VHF DSB-AM radios with 25 kHz channelisation 

and on HF voice technology in remote and oceanic regions. Although it is rare for any 

particular channel to be highly utilised, the need for a channel to be assigned to each air 

traffic controller and the coverage required for each channel has lead to saturation of the 

VHF band. A key focus for this section is therefore on methods to alleviate the current 

saturation of spectrum allocated to voice services whilst simultaneously increasing 

spectrum efficiency. The following general methods are considered: 

• The introduction of new air traffic management concepts which have inherently 

lower requirement for communication. 

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• Optimisation of analogue voice services. 

• Optimisation of current digital services. 

• Wholescale movement of current analogue services to digital (both voice and 

data, but primarily data) accompanied by an aggressive reduction in analogue 

channels. 

There is consensus within the aviation industry that the long term solution lies in the 

movement to digital technologies. There is no shortage of possible candidates, although 

the industry is slow to adopt any particular new solution primarily because: 

• global consensus needs to be obtained in order not to burden operators with 

multiple fit solutions; 

• the cost of avionics is such as to preclude regular updating of technology. 

This section assesses the possible evolution of communication services from the current 

time to beyond 2015 taking account of a wide range of possible technologies: 

• Current technologies which are already in operation: 

• VHF Voice supported by 25 kHz and 8.33 kHz channel spacing 

• HF voice 

• ACARS supported by VHF, HFDL and AMSS 

• Emerging technologies which have been subject to significant development work 

by the aviation community and, in some cases, significant deployment decisions: 

• VDL Mode 2 

• VDL Mode 3; 

• VDL Mode 4; 

• Gatelink. 

• Future technologies for which there are emerging development plans: 

• Next Generation Satellite Service (NGSS); 

• Satellite Data Link Service (SDLS); 

• 3G/UMTS (CDMA Wideband); 

• Boeing Connexion (Boeing CS). 

Note that there is some overlap between technologies providing communication services 

and those which could also support future surveillance services (this is discussed in 

section 3.3.8). 

5.2 Frequency Allocations (International & National) 

5.2.1 HF Communications (R) and (OR) 

For HF voice and data services, discrete frequency bands are allocated between 2880 - 

22000 kHz (AM(R)S). There are 9 sub-bands, with the aeronautical allocation taking 1331 

kHz in total. 

5.2.2 VHF Communications(R) and (OR) 

The VHF band for aeronautical communications stretches from 117.975 – 137.000 MHz 

(AM(R)S) globally (all 3 ICAO regions). 

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Within this band, 121.5 MHz and 123.1 MHz are reserved for emergency use, and 123.45 

MHz is allocated for air-air communications (in remote regions for airlines). 

Most of the band is used for VHF voice services, although digital ACARS services are 

spread evenly between the top and middle of the band. 

5.2.3 UHF Communications (NATO 230 – 380 MHz) 

Over 100 MHz within the range 230 – 380 MHz is designated for air-ground-air 

applications, which is managed by NATO on behalf of the Alliance. The band is allocated 

to the mobile service both internationally and nationally and is not specifically allocated for 

off route aeronautical communications. Apart from the glide path radio-navigation band at 

328.6 – 335.4 MHz (treated in the chapter dealing with aeronautical radionavigation) and 

the international distress and safety frequency for survival craft at 243 MHz, no direct use 

of the band is made for civil radiocommunications purposes. However civilian air traffic 

controllers provide ATS to military services on assigned frequencies in the band, which 

helps to avoid impacting VHF national airspace air ground communications. 

5.2.4 UHF Communications > 862 MHz – Public Correspondence 

The need for a terrestrial aeronautical public correspondence system started in the United 

States where the band 849 – 851 MHz (uplink) was paired with 894 – 896 MHz 

(downlink). This spectrum was not available in Europe. ITU WARC92 allocated frequency 

spectrum for the Aeronautical Public Correspondence (APC) service within the frequency 

bands 1670 - 1675 / 1800 - 1805 MHz ITU-RR 5.380 based on proposals from CEPT 

Administrations. This was known as the Terrestrial Flight Telephone System (TFTS). In 

the USA the service appears to be in decline with only two operators now providing 

service. In many CEPT countries TFTS networks were licensed, however the actual 

development of subscriber numbers in those TFTS networks have shown that TFTS 

networks in Europe have not been a success. The CEPT Decision designating these 

bands for TFTS has therefore been abrogated. 

ETSI is now investigating a concept which would allow passengers to use their own GSM 

telephones on board the aircraft. The proposal, GSM-A, would install a system similar to a 

GSM base station on the aircraft, which was originally intended to be linked to the ground 

over the exiting TFTS link. The power-control mechanism which already exists in the 

GSM protocol will be used to keep the power output of the telephones below the levels 

which could cause interference to avionics systems. With the probable reallocation of 

TFTS spectrum this concept will have to await the identification of alternative spectrum for 

air-ground linking. For the future it may be appropriate to consider facilities for an 

aeronautical IMT-2000 service as well as GSM. 

5.2.5 1.5/1.6 GHz – Satellite 

The following bands are available for aeronautical satellite communications: 

• 1525-1559 MHz (space-to-Earth); 

• 1626.5-1660.5 MHz (Earth-to-space). 

Note: Only those bands are indicated, where a service is provided by Inmarsat. There are 

other bands available in principle due to their allocation status. 

• In addition to its availability for routine non-safety purposes, the bands 1530- 

1544 MHz and 1 626.5-1 645.5 MHz are used for distress and safety purposes. 

Maritime GMDSS distress, urgency and safety communications have priority in 

these bands. 

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• Use of the band 1544-1545 MHz is limited to distress and safety operations, 

including feeder links of satellites needed to relay the emissions of satellite 

emergency position-indicating radio beacons to earth stations and narrow-band 

(space-to-Earth) links from space stations to mobile stations. 

• Use of the band 1 645.5-1 646.5 MHz is limited to distress and safety operations, 

including transmissions from satellite EPIRBs and the relay of distress alerts 

received by satellites in low polar Earth orbits to geostationary satellites. 

5.3 Current technology description 

5.3.1 DSB/AM (analogue) voice 

VHF DSB/AM voice is available throughout the world in 25 kHz channels. Recently, 8.33 

kHz channelisation has been introduced in Europe in high density areas, although not yet 

in the UK. The transceiver power usually takes values between 40 and 60W. 

In the UK, the “Climax system” uses offset carrier techniques to increase regional 

coverage. The principals behind Climax are described below. 

Obtaining the required wide area coverage given local line of sight constraints requires 

the use of more than one ground transmitter/receiver site. If all of these stations operated 

on the same frequency, interference would result in low frequency beat frequencies which 

would not be a problem for aviation since they could be filtered out (a similar effect is 

found in FM broadcasting but it has a low impact because of filtering). However, Doppler 

effects will cause frequency shifting depending on the location of transmitters relative to 

the aircraft path. This results in variable audio frequency beating which cannot be filtered 

without detriment to the desired audio communication. 

Climax operates by introducing significant transmission offsets between transmitter sites 

which, by careful planning, produces acceptable performance. A key part of the system is 

the narrower bandwidth for the transmission compared with the receiver performance – 

hence the receiver can receive a wide range of offset transmissions (wide receiver 

bandwidth) and interference between offset transmissions is minimised (narrow 

transmission bandwidth). 

The application of Climax to 8.33 kHz channel spacing systems is described in section 

5.6.1. 

The safety requirement for party-line communications (leading to situational awareness 

for all airborne and ground-based users) leads to a wide geographic coverage for each 

channel (and thus very poor spectrum efficiency). 

5.3.2 HF voice 

High frequency (HF) is extensively used in remote and oceanic areas, due to the ability of 

HF waves (3-32MHz) to reflect off the ionosphere and thus work over significant ranges 

(typically between 1000 and 3000 kilometres). As it is reliant on the characteristics of the 

ionosphere (and propagating atmosphere), the integrity and reliability of the signal can 

vary according to season, time of day, geographical location, and solar fluctuations. 

Transmitter powers are usually in the range of 10-200W (peak envelope performance) – 

and approximately 100W on average. 

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5.3.3 Current data link technology 

5.3.3.1 VHF data link 

VHF datalink is the traditional basis for AOC data services provided as part of the ACARS 

service. Aeronautical Mobile Satellite Service (AMSS) also supports ACARS and is also 

used as the bearer for Future Air Navigation System 1/A (FANS 1/A) 20 in the Pacific and 

North Atlantic 21 . High Frequency Data Link (HFDL) also supports ACARS. 

5.3.3.2 High Frequency Data Link 

High Frequency Data Link (HFDL) is a global end-to-end packet data communication 

system designed to function as a sub-network of the Aeronautical Telecommunications 

Network (ATN), and to provide a world-wide coverage based on operations at around 10 

HFDL ground stations. 

The use of HF and the wide coverage of each ground station (5000 km radius) means 

that HFDL is suited for the transmission of information data (neither tactical, nor strategic) 

in oceanic and remote areas. 

The characteristics of HFDL are summarised in Table 5-1 below. 


Service topology Point-to-point 

ATN compliance Yes 

Frequency band HF spectrum: 2 to 32 

MHz 

RF Channels Carrier centred at 1440 

Hz and modulated at an 

1800 Hz rate (symbol 

speed is always 1800 

baud). 

Modulation scheme M-PSK modulation (2-PSK, 4-PSK or 8-PSK) 

Bit rate 300, 600, 1200, or 1800 

bps. 


method 

System with 4 to 6 families of 5 to 6 HF frequencies 

each, based on operations at 8 to 10 HF Datalink 

ground stations for world wide coverage 

Four data rates are usable, based on signal quality, 

depending on the atmospheric conditions (impacting 

the SNR):300, 600, 1200, and 1800 bps. 

Reserved or random Each slot can be designated either for uplink, for 

downlink for a particular aircraft (reserved slot) or for 

contention downlink (random access). 

Uses a protocol consisting of a combination of 

Frequency Division Multiple Access (FDMA) and slotted 

Time Division Multiple Access (TDMA) 

20 

FANS 1/A is the system, including avionics, to support digital controller-pilot dialogue 

primarily in the oceanic region 

21 

The ACARS VHF Datalink is also used to support the FANS1/A applications where 

there is coverage. 

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Frequency availability 


Available Band globally available. 

Dependencies Time-source Each ground station needs a time reference for the 

proper working of its squitter. The access to the 

physical medium is a random access to avoid the 

collision as far as possible, and there is a need for 

temporal co-ordination in this procedure. 

Power Ground – 6kW or less 

Air – 400W or less 

This is the transmitter peak envelope power [ref ICAO 

SARPS – Annex 10]. 

Table 5- 1 HFDL Characteristics 

5.3.3.3 AMSS 

The AMSS is a mobile communications system intended for provision of digital voice and 

data communications services to and from aircraft. The range of possible applications for 

these services includes airline passenger communications (public correspondence), 

airline operations communications and air traffic control services. 

The major elements of AMSS are: 

• Space Segment: in particular the satellite communications transponders and 

associated frequency bands assigned for use by the Aeronautical Mobile 

Satellite System. The space segment uses transparent payloads. 

• Aircraft Earth Stations (AES) which interface with the space segment (at L-band) 

for communications with Ground Earth Stations, and which interface in the 

aircraft with ACARS and other data equipment, and with crew and passenger 

voice equipment, in accordance with the relevant technical and operational 

requirements; 

• Ground Earth Stations (GES): Which interface with the space segment (at Cband 

and L-band) and with the fixed networks, and which are operated in 

accordance with the relevant technical and operational requirements for 

communications with AESs; GESs operate to their own essentially independent 

but interlinked networks; and 

• Network Coordination Stations (NCS): Located at designated earth stations, 

which interface via the space segment (at C-band and L-band) with the GESs for 

the purpose of allocating satellite channels. 

AESs supporting circuit-mode voice services (Classes 2 and 3) are classified according to 

the type of voice services that they can support; that is safety or non-safety. The Inmarsat 

safety/non-safety classification concerns only the minimum EIRP supported by the AES 

installation. This in turn reflects a theoretical voice channel return link availability that is 

expected for a particular AES. 

It should be noted that AESs which do not meet the minimum EIRP for the safety 

classification will not comply with the existing minimum EIRP requirements of ICAO 

SARPs or RTCA MOPS for voice services. The relaxed EIRP requirements for the nonsafety 

classification are intended to meet the needs of those AES users wishing to carry 

aeronautical public correspondence circuit-mode traffic only, at the lower channel 

availability figure. 

Both safety and non-safety AESs are fully compliant with the ITU International Radio 

Regulations criteria for the use of the AMSS band and provide for strict observance of the 

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absolute priority which is required to be given to distress and urgency, ATS and AOC 

traffic over APC traffic. 

Channel Types 

The characteristics of AMSS are summarised in Table 5-2 below. 


Service topology Point-to-point 

ATN compliance Yes Only available with Data 3 mode. 

Frequency band Ka and L-band Inmarsat uses only 3 MHz today. 

RF Channels C-Channel (Voice) 

P- R and T-Channel 

(Data) 

Modulation scheme A-QPSK (Voice) 

A-BPSK (Data) 

Bit rate 21 kbps (Voice) 

10.5 kbps (Data) 

Service Link: 

Satellite to AES: 1544-1555 MHz 

AES to Satellite: 1645.5-1656.5 MHz 

Feeder Link: 

Satellite to GES: 3600-3620 MHz 

GES to Satellite: 6425-6440 MHz 

Lower data rate channels (600 and 1200 bps) 

used for Aero-L 

Channel access method TDMA and Random Channel access is by random slotted ALOHA, 

GES then control channel using TDMA. 



Global allocation 

Dependencies Ownership The service depends on the INMARSAT satellite 

constellation with the exception of the Japan Civil 

aviation with MSAS system. 

Table 5- 2 AMSS Characteristics 


The RAF and guest air forces make extensive use of the 230 – 380 MHz band for 

aeronautical mobile operations. The band is used primarily for military functions, including 

air ground communications and ATC for military functions. NATS provides ATC functions 

for military aircraft essentially identical to the ATC communications in the VHF band. In 

most areas NATS transmits ATC information simultaneously on VHF and UHF channels 

for military aircraft which are not equipped with VHF equipment. Military aircraft therefore 

remain aware of civilian aircraft and vice versa. Military uses include but are not limited to, 

coordination of in-flight refuelling, vectoring of aircraft to targets and large scale training 

exercises. Military ATC involving ground control, approach control, training flights, combat 

etc would typically make exclusive use of the UHF band. 

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5.3.5 UHF Communications > 862 MHz – Public Correspondence 

Terrestrial public correspondence systems are in decline, the service provided did not 

meet market expectations. The optimal solution would be to extend the ‘virtual home 

environment’ to the air. In other works provide technical solutions which allow an aircraft 

to become a visited public mobile telecommunications network and permit roaming of 

terminals onto the internal network, GSM or IMT-2000. 

Satellite 1.5/1.6 GHz Inmarsat systems also provide an opportunity to provide public 

correspondence for passengers. 

The average power of a UHF transceiver is between 20 and 30W. 

5.4 Operational requirements 

5.4.1 Overview of operational requirements 

Communication is an essential part of air traffic service (ATS) provision and, for tactical 

control of aircraft, provides a safety critical link between pilot and controller. Other ATS 

requirements include delivery of air traffic information services (ATIS). 

Aeronautical communications also includes non-ATS communication such as: 

• AOC – Airline Operational Communications; 

• AAC – Airline Administrative Communications; 

• APC/IFE – Airline Passenger Correspondence/In Flight Entertainment. 

AOC supports the regularity of flight and is considered as safety related. AOC is 

traditionally supported by the same media as ATC. 

Support for AOC applications is important to all airlines as it is seen as a key enabler of 

operational efficiency benefits. 

AAC and APC/IFE are non-safety related. AAC relates to typically narrow band 

applications that support the airline operation but are not concerned with the safety and 

regularity of flight, for example baggage handling. APC/IFE however has significantly 

different characteristics to ATS communications and typically requires a broadband 

solution. 

There is increasing demand for all of these services as well as a new and increasing 

demand for security related services such as video links from the cockpit. 

5.4.2 Role of HF and HFDL in supporting the operational requirements 

HF and HFDL are the only terrestrially-based means of communicating from remote or 

oceanic areas – VHF and other ground-based frequencies propagate by line-of-sight. 

ATC, weather and airline operations communications are passed via HF/HFDL. 

As such, HF is necessary for the foreseeable future to provide redundancy for satellite 

communications. Indeed, due to the cost of satellite communications, many users prefer 

HF/HFDL in spite of the limitations. Also, satellite communications have a limited 

coverage at the poles. 

EUROCONTROL’s view is that there is a need to extend the allocation by at least 30 kHz, 

due to increases of HF traffic of 9% per year in an already congested band. ICAO is 

investigating the possibility of moving into the 5MHz band currently occupied by AMS 

(OR). The introduction of HF datalink has increased the use of the band, and it is still 

being implemented world-wide. 

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Note that HF also carries airline operator communication and this requirement is 

increasing. 

5.4.3 Role of VHF analogue communications in supporting the operational 

requirements 

VHF voice is the primary communications band for line-of-sight air-ground 

communications in terrestrial regions and is used at all airports, for en route, approach 

and landing phases of flight and for a variety of short-range tasks for general aviation and 

recreational flying activities (e.g. gliders and balloons). 

VHF voice is considered vital to ATC for the foreseeable future. The benefits of party-line 

communications, and the tactical nature of voice, allows controllers and pilots to interact 

in real-time to ensure the safety and flow of traffic. The voice communications between 

pilots and airline operations centres (AOCs) are not considered as essential, but are still 

desirable. 

5.4.4 Relationship between airspace capacity and VHF spectrum 

requirements 

The operational requirements for voice communication have a number of characteristics 

which lead to inefficient use of VHF spectrum: 

• A requirement for an immediate “permanently on” link between controller and 

pilot – this leads to a requirement for dedicated VHF channels. 

• A link is required between the controller of a sector and all aircraft in that sector. 

A sector is a large geographical region which delineates a controller’s region of 

responsibility. It is an operational requirement that the communications limit is 

beyond the controller’s region of responsibility. This need for wide area coverage 

complicates the assignment of transmitters and receivers, restricts the scope for 

frequency re-use and leads to the need for “offset carrier” techniques which are 

almost unique to the UK and which require 25 kHz channelisation (note that 

NATS appears to use larger en-route sectors than elsewhere in Europe). 

• There is a requirement for a party line in which all aircraft in a sector can hear 

each other as well as the controller. This enforces simplex communication and 

further limits the scope for frequency re-use (line of sight ground to air is much 

shorter than line of sight air to air). 

• Radio communication between a controller and aircraft under control generally 

takes up 10 to 20% of a controller’s time. Hence, basic channel utilisation is low. 

Taken together the overall spectrum efficiency of the VHF band is extremely poor 

compared to almost any other system. The result is that, although there is significant 

bandwidth available, service providers in general, and NATS specifically, are struggling to 

meet new requirements for voice channels. NATS report that some requirements for enroute 

sectors have not been met for 4 years. 

Note that although there is a one to one mapping between a sector and a channel, the 

demand for channels is not static since NATS regularly opens new sectors in a bid to 

provide more airspace capacity. Effectively, there is a trend to more, smaller sectors 

through a process known as systemisation. This has helped NATS cope with increasing 

traffic demand over the last 20 years. 

However, systemisation is a process subject to diminishing returns (simply put, smaller 

sectors means more coordination between the controllers in neighbouring sectors and 

this in the end dominates controller workload, limiting the scope for the addition of further 

sectors). Hence NATS (in common with other service providers) will have to find other 

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mechanisms to provide more airspace capacity and this in itself will provide a brake on 

the demand for channels. 

New operational concepts which could provide more airspace capacity without increasing 

the demand for voice channels include: 

• Greater automation of the controller processes. A variety of controller tools are 

being developed to assist the control process. Many of these rely on improved 

surveillance data, such as that provided by Mode S enhanced surveillance (see 

Chapter 3). Through its current radar procurement programme, NATS will put in 

place infrastructure that can provide suitable surveillance data. It is believed that 

NATS is also intending to introduce an initial suite of controller tools based on 

this infrastructure which should at least slow down the requirement for more air 

traffic sectors in the time frame 2007 – 2011. 

• Larger en-route sectors through a combination of planned trajectories and 

successive delegation to the pilot. New concepts are being developed in which 

large increases in airspace capacity are provided through a combination of a) 

much greater cooperation between ground and air to plan conflict free 

trajectories and b) responsibility for parts of the control process being delegated 

to the pilot. The details are still be researched and validated but there is the 

possibility that the size of air traffic control sectors could actually be increased, 

thus lowering the requirement for voice channels in the timeframe 2012+. 

5.4.5 AMSS 

Although AMSS provides a global service, it is high cost compared with the other links 

and hence its use is generally limited to: 

• passenger services 

• low levels of ATS and AOC traffic in oceanic regions 

5.5 Regulatory and Standardisation Issues 

5.5.1 HF Communications (R) and (OR) 

The planned development of digital communications over power lines, the increase in 

cable TV and broadcasting services all lead to considerable pressure on the HF band. 

The underlying level of interference is growing, leading to a further reduction in the 

performance of HF aeronautical communications. 

ICAO would like to protect the current allocations from competing users (examples 

include mobile services, cable TV and digital communications via power lines). 

5.5.2 VHF Communications Analogue and Digital (R) and (OR) 

The main issue is the compatibility of the VHF frequencies (117.975-137.000 MHz) and 

the sound broadcasting service in the 87-108 MHz band (i.e. FM radio). 

Due to cost issues in retro-fitting, many GA radios cannot handle the additional 

frequencies recently allocated for VHF voice – 136-137 MHz. As such, design and 

channel allocation needs to take this into account. 

5.5.3 Extension of VHF band 

Section 3.4.10 highlighted the potential for the decommissioning of VORs operating below 

the current communications band. This offers the possibility of establishing new 

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communication services which could, through a transfer of voice to data, alleviate 

congestion in the current band. 

It is understood that NATS’ intention is to start the process of moving out of VOR 

operations as soon as possible. However, NATS has concerns about whether this is 

permitted by the terms of its operating licence and whether the need to support general 

aviation users would prevent wholescale de-commission of VOR. 

One conclusion of the ITU’s World Radiocommunications Conference in 2003 (WRC- 

2003) was that consideration for additional radio spectrum allocation for aviation could be 

made in the range 108 MHz to 6 GHz including consideration of current satellite 

frequency allocations. The ITU would assess new requirements against the overall need 

to develop spectrum efficient systems. Consideration of extension of the VHF band could 

therefore be made within the terms of this proposed review. 

5.6 Possible Improvements to existing technology 

5.6.1 VHF voice: 8.33 kHz channelisation 

A migration from 25 kHz channels to 8.33 kHz channels has been implemented at high 

altitude in Europe, although not extensively yet in the UK. As a result of an equipage 

mandate, the air transport fleet is largely equipped with 8.33 kHz capable radios. A more 

widespread use of 8.33 kHz is being promoted as a short-term solution to frequency 

congestion in the VHF band. 

CAA believes that the move to 8.33 kHz would give UK enough spectrum to meet 

demand for analogue voice services until 2020 (equivalent figures for Europe as a whole, 

tend to quote 2015 as the “saturation point”). 

NATS is planning a transition to 8.33 kHz operations although there are a number of 

barriers which have acted to slow down implementation: 

a) Equipage of general aviation aircraft which acts to limit the potential for 

implementation at low altitudes. Note that an effective initial implementation would be 

to follow corridors i.e. down to Heathrow since 8.33 kHz is easier to implement at low 

level since there is no need for offset carrier systems. However, this would require 

widespread equipage in the GA fleet. 

b) Difficulties implementing 8.33 kHz over the wide geographic areas serving en-route 

sectors. This is because the Climax offset carrier system cannot be used as 

effectively with 8.33 kHz since 8.33 kHz cannot contain as many offset carriers as a 

25 kHz channel 22 . This limits the potential use of 8.33 kHz to smaller sectors. 

c) NATS has identified a number of sectors that could transfer to 8.33 kHz but is 

currently unable to implement them because its voice distribution and switching 

infrastructure (i.e. the interface between the ground and airborne segments) is not 

ready. This restricts the rate of implementation above FL245. 

d) Equipage of military aircraft would also need to be addressed prior to 

implementation. 

22 Note that a recent EUROCONTROL study has highlighted difficulties with current 8.33 

kHz radios that may limit even further the opportunity to implement a Climax system. 

Clearly more work is required to determine how wide area coverage can be provided in 

an 8.33 kHz environment. 

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5.6.2 Movement of HF voice services to HFDL 

The implementation of HFDL may reduce the number of voice messages being passed 

(and the duration of each message), leading to a more efficient use of the spectrum. 

5.6.3 Movement of HFDL to Satcom 

Satellite communications may be used for remote/oceanic regions. However, coverage is 

poor near the poles, and the cost/benefit case for users (in particular, airlines) means that 

many continue to prefer HF communications. 

A low-cost satellite communications solution is not likely in the near future. As such, the 

cost-benefit case for HFDL continues to be a driver for airline equipage. 

5.6.4 VHF datalink: upgrade of ACARS to VDL Mode 2 and initial transfer 

of ATIS and controller pilot dialogue 

The move to datalink communications may increase the performance for VHF (with VDL 

Mode 2, Mode 3 and Mode 4 offering potential improvements in spectrum efficiency 

compared to VHF voice). 

VDL Mode 2 (VDL2) provides an air/ground bit-oriented point-to-point VHF data link which 

is compatible with the aeronautical telecommunication network (ATN). VDL2 is designed 

to support both AOC and ATS applications, and for many airlines is seen as an upgrade 

to ACARS for their AOC communications needs. 

Airlines and the data link service providers ARINC and SITA are pushing ahead with an 

initial implementation of VDL2 which uses VDL2 as an improved carrier for the ACARS 

service. This is termed ACARS over AVLC (AOA). Substantial levels of implementation 

are expected by 2010. 

EUROCONTROL has progressed the VDL2 system for use for ATS applications under the 

PETAL II, Euro VDL2, and Link 2000+ programmes. 

The Link 2000+ programme aims to use VDL2 to support initial data link services such as: 

• Data Link Initiation Capability 

• Digital ATIS 

• ATC Communication Management. 

• ATC Clearances and Flight Plan Consistency are also planned to be 

progressively introduced in the en-route environment in a second phase of the 

Link 2000+ programme. 

VDL2 uses a Differential 8-Phase Shift Keying (D8PSK) modulation scheme and a CSMA 

medium access protocol (Collision Sensitive Multiple Access) similar to the VHF ACARS 

scheme. One VHF channel is shared by many aircraft and ground stations. 

Interference testing of VDL2 to assess frequency compatibility with other onboard 

systems has been carried out by EUROCONTROL and is now complete. EUROCONTROL 

has progressed frequency planning at recent ICAO FMG meetings, and has specified a 

number of steps to vacate the necessary frequency channels. 

According to the EUROCONTROL plan presented at FMG, in Europe VDL2 is planned to 

operate in four frequencies at the top of the COM band: 136.975, 136.925, 136.875, and 

136.825 MHz. This involves clearing existing users of the channels away from these 

channels, and into other channels lower in the spectrum. 

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The figure below shows the possible steps as outlined in the EUROCONTROL plan: as the 

current situation (labelled 2001), a possible intermediate step (middle column), and the 

channels as they could be in 2010 (right column). 

Figure 5-1: Proposed EUROCONTROL frequency plan for the EUR region 

SITA and ARINC have plans to deploy a ground VDL2 infrastructure (60-80 units for 

SITA) that will cover all Europe. ARINC advertises in 2002 that it has already installed 

VDL2 ground stations in 110 sites across the US, and at three sites providing coverage 

across southern France. 

In addition, the LINK 2000+ Programme objective is to plan and co-ordinate the 

implementation of operational air/ground data link services for Air Traffic Management 

(ATM) in the core area of Europe in the timeframe 2000 – 2007. Thus while ARINC and 

SITA develop the ground infrastructure (for AOA and ATN), the EUROCONTROL 

programmes are implementing the ATS data link services. 

The characteristics of VDL Mode 2 are summarised in Table 5-3 below. 


Service topology Point-to-point Support for broadcast DLS addresses is mandatory, 

and support for broadcast DLS connection 

establishment is optional. 


Frequency band 118.000 MHz – 136.975 

MHz 

RF Channels 25 kHz channels 

Transmission Power Limited to 15W 

Potential for 720 channels. 

A common signalling channel is allocated worldwide at 

136.975 MHz 

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Modulation scheme D8PSK D8PSK at 10.5 symbols/s 

Bit rate 31.5 kbits per second 


method 



p-persistence CSMA-CD Carrier Sense Multiple Access with Collision Detection 

Currently only the CSC 

(136.975 MHz) is 

dedicated to VDL-2. 

Expected that 4 

frequencies will be 

dedicated to VDL-2 

(136.975, 136.925, 

136.875, and 136.825). 

Dependencies Airborne VDR supporting 

VDL2 frame 

transmission. 

Ground VHF Data Radio 

stations deployed by the 

Air/ground 

communication service 

provider. 

Table 5- 3 Characteristics of VDL Mode 2 

This band is completely saturated in the western part of 

Europe making the allocation of channels difficult in the 

near future. 

Some services used locally by some airports or ACCs 

shall be moved from the 136.7MHz, 136.725 MHz and 

136.750 MHz frequencies (in France, Germany, 

Sweden, Italy). 

SITA is granted licences for Amsterdam and CDG 

airports on the CSC frequency. 

Avionics implementation is specific: the physical and 

MAC layer are implemented in the radio (VDR) while 

the other layers (LME and above) are implemented in 

the CMU/ATSU hosting all the communication stacks 

(ATN router and application services). 

5.6.4.1 Impact of VDL2 on spectrum efficiency 

The replacement of ACARS by VDL Mode 2 is expected to provide a 10-fold increase in 

spectrum utilisation from an ACARS baseline of typically 300bps. Simulations are ongoing 

in EUROCONTROL to demonstrate the data capacity of a VDL Mode 2 channel. 

There is also potential for the move of voice services to data, beginning with VDL2. The 

obvious first choice of service is to move ATIS to digital since these are uplink broadcast 

services which can make best use of the relatively high bit rate of VDL2 whilst having 

lower vulnerability to message loss as a result of interfering transmissions from other 

stations. Such a move would be spectrum efficient and could be accompanied by a 

parallel decrease in the number of analogue voice channels allocated to ATIS. 

A further stage of interest is the transfer of controller pilot dialogue as described above. 

This is primarily of interest as a proving ground and is judged unlikely to offer a long term 

solution. The reasons for this judgement include: 

• VDL2 employs a random access mechanism with little protection against 

overload and no priority mechanism; 

• it is therefore unsuited to tactical controller/pilot dialogue and hence only a 

fraction of controller/pilot dialogues could be transferred; 

• hence there would be little or no impact on the requirements for voice channels 

since a channel will still have to be reserved per sector. 

Furthermore, issues relating to the data rate of VDL 2 for en-route and terminal area 

airspace scenarios have been raised indicating that VDL2 may not be a particularly 

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efficient solution (this relates both to the data rate achievable in en-route and terminal 

point to point scenarios and the need to use 25 kHz guard channels). 

5.6.5 VHF voice: reducing long term spectrum requirements for voice 

The introduction of 8.33 kHz channel spacing will alleviate current congestion. The 

transfer of some voice services, such as ATIS, to data will also free up a small number of 

voice channels. In the longer term, it can be expected that most other ATS 

communication will be transferred to data. This development will lower the utilisation of 

each voice channel such that the case for maintaining a single voice channel per sector 

will become increasingly unattractive from the point of view of spectrum utilisation. 

Furthermore, as the demand for data communication increases, voice spectrum will come 

under increasing pressure for re-allocation to data services. 

The study team is unaware of studies into the re-organisation of spectrum once there has 

been significant movement to data services. However, it appears appropriate to 

investigate now how such a re-organisation could take place. 

A number of items for consideration are set out below. 

5.6.5.1 Investigate long term channel utilisation 

As described above, in current operations a very large cell size is required on account of 

the need for party-line communication in large sectors. The utilisation of a single channel 

reaches a typical maximum of 10-20% (meaning that the channel is being used for 

communication 10-20% of the time and unused during the rest of the time) [ICAO Doc 

9718]. However, although the channel is not particularly highly used, from the point of 

view of the control process, communication is a regular event and essential to the control 

process. Hence many channels are required to serve the large number of sectors in UK 

airspace. 

Contrast this with the operation of the emergency channel. Utilisation is very low, 

presumably so low that the probability of two aircraft using it at the same time is very 

small. In this case, a single frequency is used for the whole of the UK using offset carrier 

techniques. 

The transfer of ATS communication to data will result in a reducing channel utilisation 

such that, at some point, it might become feasible to serve a number of sectors with the 

same channel. The point at which such a development becomes acceptable to controllers 

and the safety regulator requires further investigation. If it is possible to amalgamate 

channels in this way, it becomes possible to derive a strategy for the introduction of data, 

accompanied by an ongoing consolidation of voice allocations. 

The study team is unaware of any studies of the utilisation of channels although it is 

understood that CAA are about to carry out a study on utilisation in terms of how 

effectively channels are planned against each other. 

5.6.5.2 Investigate introduction of digital voice 

An alternative strategy for voice in the longer term is to introduce digital voice. From the 

point of view of efficient spectrum utilisation a system based on a commercial standard 

which allows for trunking of voice calls seems the most attractive, since the provisioning 

of channel allocation can simply be scaled according to need. In such a system, a 

controller could maintain near immediate access to a particular aircraft. The need for 

maintenance of a party line with a group of other aircraft could also be investigated. 

The introduction of digital voice burdens operators with an additional system with which to 

equip and hence such a solution is unlikely to be attractive in the short or medium term. 

Page 159


A large amount of the spectrum used for air-ground-air communications is believed to be 

used for mainly narrow-band systems carrying a single 25 kHz speech or data channel. 

Frequency hopping is also employed for secure communications within the air-ground-air 

bands. 

The study team believes that spectrum in this range is a valuable commodity and the use 

of spectrum efficient equipment should also be an operational requirement for defence 

forces provided operational efficiency is not impaired. The introduction of 8.33 kHz 

channel spacing replicating the civil situation would be a first step. A second step would 

be to again transfer of some voice services, such as ATIS, to data. In the longer term, it 

could be expected that as per the civil community most other ATS communication will be 

transferred to data. 

There might even be a possibility for the UK to take a lead in this regard provided UHF 

radios fitted in military aircraft operating in UK air-space were capable of utilising 25 kHz 

and/or 8.33 kHz channelling. This part of the spectrum is already used for land mobile 

applications in Ireland, it would seem feasible to similarly use spectrum further east in the 

UK if the NATO air-ground-air bands could be reduced from around 100 MHz to 50 MHz. 

Obviously co-ordination with mainland Europe would be an issue but this should be a 

process managed by NATO, CEPT and national administrations in an orderly manner 

with an eventual goal of recovering spectrum on a European basis. 

A further issue concerns the use of UHF (or VHF) PBR frequencies at airports by the CAA 

for ground movement control around the airfield. It would seem that some of these 

requirements could be addressed by other systems. Emergency services might be 

embraced by the Airwave TETRA emergency system. Furthermore, now that VHF 

aeronautical spectrum can be used for ground vehicles there may be further possibilities 

for the use of company channels and other channels assigned to operational ground 

vehicles. Once an aircraft moves ‘off stand’, it has a need to know what traffic is in the 

taxiways. Previously a ‘follow me’ vehicle would have to use UHF cross coupled to VHF in 

order to get back to the tower controllers. It would therefore seem appropriate to consider 

using VHF aeronautical frequencies wherever possible and as a consequence it may be 

possible to reduce the use of PBR frequencies at airports. 

5.7 Possible New Technologies (in-band) 

5.7.1 Emerging technologies 

The previous section discussed the general need to move current voice services to data. 

This could be digital voice or digital data. This section discusses some of the options for 

future digital links in bands already allocated for aeronautical use. 

There are a number of emerging technologies which are yet to enter operational service 

but for which significant standardisation, development and trials work has been carried 

out. These technologies could see implementation from 2007 onwards. The identified 

technologies are: 

• VDL3; 

• VDL4; 

• Mode S SSR 

Note that Mode S Data Link has been standardised by ICAO as a potential data link. No 

stakeholder has plans to implement Mode S Data Link. However, the study has provided 

a brief consideration of this link. 

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5.7.2 VHF Communications Digital Links 

Note that, although the VHF spectrum is already congested with the result that it is 

currently difficult to launch new digital services, the aeronautical community has 

reasonably unchallenged access to the VHF band and it makes sense to use the band for 

digital communication where possible. Hence the introduction of an efficient VHF link, 

either narrow band or wideband, together with a concerted effort to clear out analogue 

channels is a reasonable strategy, albeit one which will face initial barriers related to 

current spectrum shortages. 

VHF datalinks are being standardised, and will be fully implemented in the next few years. 

VDL Mode 2 is the first candidate and, as discussed above, is undergoing initial 

implementation. VDL Mode 3 is being considered mainly in the USA and VDL Mode 4 is 

being considered in Europe, Russia and Asia. Implementation would lead to a decrease 

in the reliance on analogue techniques. 

5.7.2.1 VDL Mode 3 

The VHF Digital Link Mode 3 (VDL3) system provides multiple channels to operate on 

one 25 kHz frequency assignment. The VDL3 system uses the same physical layer as 

VDL2 (D8PSK modulation), provides a data service and also employs a 4.8 kilobits per 

second vocoder for voice operation. 

VDL3 has been selected by the FAA for the future provision of voice and data 

communications, and forms the basis of the FAA’s Next Generation Air/Ground 

Communications (NEXCOM) programme. (Note that it is possible that the FAA will 

abandon its VDL3 programme in favour of implementation of 8.33 kHz analogue voice 

systems – no firm decision has been made although one could be expected in the next 

year). 

The FAA will deploy VDL3 to support voice in the high-altitude en-route airspace by 2009 

and data around 2012. The FAA does not propose to offer AOC services through their 

VDL3 network. 

VDL3 employs Time Division Multiple Access (TDMA). The system divides a radio 

transmission into four 30-millisecond segments which equates to a 120-millisecond frame. 

Each of these segments can be assigned to different user groups to achieve a theoretical 

four-fold increase in effective use of a channel. 

The system software digitises and compresses 120 ms of the sound into 576 bits that are 

transmitted in one burst during a 30-millisecond segment. By using the same software to 

decompress the burst on the receiving end, high quality reproduction of voice waveforms 

is achieved. Because the basic transmission of the radio is a digital signal, data can also 

be transmitted on one of the other time division slots. 

The VDL3 system provides for a variety of different system configurations. The various 

configurations differ in the way that the different time slot resources are allocated to 

different user groups. A user group consists of a ground radio and a number of airborne 

radios which are all interconnected by voice and/or data communications. 

At any given time different user groups can be in different configurations. An airborne 

radio does not need to know configuration information prior to net initialisation. This 

information is provided by the ground station. 

There are 4-slot configurations and 3-slot configurations. The 4-slot configurations 

provide guard time sufficient to allow interference-free communication up to a range of 

200 nautical miles (nm). For long range scenarios, the 3-slot configurations provide for 

600 nm. 

The 4-slot configurations include the following: 

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• 4V. Provides 4 voice channels (no data) in one 25 kilohertz (kHz) channel. This 

mode may, as an option, include data downlink using the management (or “M”) 

channel transmissions and features such as urgent/priority access, 

semiautomatic frequency change, and caller ID. 

• 2V2D. Provides 2 voice and 2 data channels in one 25 kHz channel. These are 

paired so that one user group uses one voice and data time slot pair and a 

second, independent, group uses the other voice and data pair. 

• 3V1D. Provides 3 voice channels and 1 data channel in one 25 kHz channel. 

The three voice channels are completely independent; however, the single data 

channel is shared by the three user groups. 

• 3T. Provides a trunked capability shared by all users in one 25 kHz channel in 

which 1 out of 4 time slots is available for voice or data and 2 out of 4 time slots 

are available exclusively for data. The fourth time slot is used exclusively for 

channel management functions. 

The 3-slot configurations include the following: 

• 3V. Provides 3 voice channels (no data) in one 25 kHz channel. This mode is 

analogous to 4V, but provides more propagation guard time. 

• 2V1D. Provides 2 voice and 1 data channel in one 25 kHz channel. This mode is 

analogous to 3V1D, but provides more propagation guard time. 

• 3S. Provides a single voice channel in one 25 kHz channel. The same digital 

voice bit-stream can be transported on each of 3 time slots used by 3 separate 

ground sites to provide coverage over an area larger than that which could be 

provided by a single ground site. 

• 2V1X. Provides 1 wide area voice channel for 2 separate ground stations and 

reserves another independent channel in one 25 kHz channel. The independent 

channel is defined separately in its own beacon. 

The ICAO standards for VDL3 are complete. RTCA has developed MASPS and MOPS 

for the system. No activity is underway in EUROCAE, ETSI, or AEEC. 

The characteristics of VDL Mode 3 are summarised in the table below. 


Service topology Point-to-Point Broadcast uplinks can also be supported 

Uplink and Downlink broadcast are the primary 

mode of operation for voice communications. 

ATN compliance Yes Additional voice services also included. 

Frequency band 118 – 136.975 MHz Provides up to four voice/data circuits on a 

single 25 KHz channel assignment. 

RF Channels Single 25 KHz channel 

Transmitter power Typically 15W 

Modulation scheme D8PSK 

Bit rate 31.5 kbps A EUROCONTROL study has estimated the 

effective data rate as 5040 bps. 

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method 



TDMA Limited to 4 slots 

No operational frequencies 

currently assigned in Europe 

or North America 

Typical Configurations 

4 Slot: 

4V (4 voice) 

3V1D (3 voice / 1 data) 


3T (trunked voice and data) 

3 Slot (extended range): 

3V (3 voice) 


3S 

2V1X 

Dependencies Synchronised time source needed to maintain 

TDMA timing for multiple ground stations 

operating simultaneously on the same frequency 

in a given area. 


5.7.2.2 VDL Mode 4 

VDL Mode 4 (VDL4) is a digital data link designed to operate in the VHF frequency band 

using one or more standard 25 KHz VHF communications channels. It is capable of 

providing both point-to-point and broadcast services between mobile stations, as well as 

between mobiles and fixed ground stations. 

VDL4 has support in some European states, particularly from Sweden, Russia, Germany 

and Italy as well as some Low Cost Carriers and the General Aviation Community, but is 

not well supported in the US. Comm4Solutions propose a network of VDL4 ground 

stations for AOC. The system has undergone significant development and demonstration 

in Europe, with particular emphasis so far on its ability to support ADS-B applications. 

VDL4 uses the Gaussian-filtered Frequency Shift Keying (GFSK) modulation scheme 

which has a modulation rate of 19,200 bits/s. 

Access to the VDL4 medium is time-multiplexed. The system uses the Self-organising 

Time Division Multiple Access (TDMA) concept, known as STDMA, which was invented 

and developed in Sweden. 

The STDMA scheme firstly divides the communication channel into 'time-slots'. Each 

time-slot may be used by a radio station (whether mounted on aircraft, ground vehicles or 

at fixed ground stations) to transmit a message. 

Secondly, access to the time-slots is organised. This means that each station is 

responsible for prior selection and reservation of the slots it wishes to use. The use of 

organised time-slots reduces the chances of message conflict. 

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In order to transmit at the correct time and to ensure global co-ordination between all 

participating stations, each station requires an accurate time source. In VDL4, the timeslots 

are all synchronised to UTC time, normally provided by a GNSS receiver. 

Slots are grouped into superframes, each 1 minute long, with 4500 slots in every 

superframe. Thus there are 75 slots per second, and each slot is 13.33 ms in duration. 

A position report typically occupies one time-slot while other transmissions, such as 

ground station transmissions, may occupy more. 

The self-organising concept allows VDL4 to operate efficiently without a centralised coordinating 

station, thus eliminating the need for a ground infrastructure. Ground stations 

may however serve an important role providing other services that enhance VDL4 

operations. 

VDL4 is foreseen to operate on specific channels, called Global Signalling Channels 

(GSCs), which should eventually be allocated worldwide. In high traffic-density airspace, 

the GSCs will be supplemented by Regional Signalling Channels (RSCs), or by Local 

Signalling Channels (LSCs). The GSC channels will be used by all participating stations, 

and used by ground stations to broadcast Directory of Services (DoS) information about 

the services available on the GSC channels, and on regional or local channels. 

Frequencies for VDL4 in Europe have been proposed by EUROCONTROL. The plan 

foresees making way for the VDL frequencies at the top of the 117.975 – 137.000MHz 

band and has been approved by the ICAO Frequency Management Group in Europe. 

There is a debate as to whether VDL4 will be able to use frequencies in the 108.000 – 

117.975 MHz band. The FAA view is believed to be that VDL4 frequency assignments in 

the US would probably have to be in the 117.975 – 137.000MHz band. 

It is intended that VDL4 will operate on 25 KHz frequency channels in both the 117.975 – 

137.000MHz and 108.000 – 117.975 MHz frequency bands. 

VDL4 SARPs were published by ICAO in late 2001. Work on updating the Technical 

Manual for improvement of point-to-point communications has recently been completed, 

and awaits publication by ICAO. There are a number of patent issues associated with 

VDL Mode 4 which are common with the Maritime AIS system (see section 6.10 for a 

discussion of AIS and the associated patent issues). The key result of a European 

Commission study of the patent issues is that “...the attitude of the patent holders is 

reasonable and that information provided on the patents could not be considered as 

insufficient to cover the needs of a standardisation body such as ICAO...” (see 

http://www.gpc.se/patent/ecpatent.doc). 

VDL4 ADS-B MOPS were published as Interim MOPS by EUROCAE in mid-2001. A 

European Norm for VDL4 ground stations has recently been produced by ETSI. 

The characteristics of VDL Mode 4 are summarised in the Table 5-5 below. 


Service topology Air-air broadcast 

Uplink broadcast 

Downlink broadcast Airair 

point-to-point A/G 

point-to-point 


Frequency band 108-136.975 MHz Allocations of required channels could be in either 

Page 164


RF Channels Multiple 25 kHz channels the 117.975 – 137.000MHz or 108.000 – 117.975 

MHz bands. No global allocation has yet been 

determined. 

Transmitter power Airborne – 20W 

Ground – 32W 

Modulation scheme Binary GFSK 

+/- 2400 Hz 

Bit rate 19200 bit/sec 

To support ADS-B applications VDL4, four 

channels are recommended 2 and 2 regional. 

Additional local channels would also be required 

for airport surface operation. 

Note that for small aircraft (GAT), the power is 

4W (VDL Mode 4 MOPS). 

Channel access method STDMA Self-Organising TDMA with nominally 75 slots per 

second per channel. 


5.7.2.3 Prospects for VDL3 and VDL4 

The general view in Europe is that, since 8.33 kHz will provide Europe’s voice needs until 

2015, the potential advantages of VDL3 are reduced. The airline community do not favour 

VDL3 – hence the view of the study team is that VDL3 is unlikely to enter operational 

service. 

The view on VDL4 is more complex since VDL4 offers a wider range of communication 

services than other VDL modes and hence is also a candidate for ADS-B. 

EUROCONTROL is considering VDL4 as a potential communication and ADS-B link for 

implementation from 2010 onwards. No decisions have been made. From the point of 

view of communication modes, VDL4 has a number of advantages over VDL2 including 

an access mechanism that provides efficient channel re-use and hence potentially greater 

effective data rates in en-route scenarios. Crucially, VDL4 supports priority and preemption 

and hence is well suited to tactical data links. Hence, the wholescale transfer of 

controller pilot dialogue is possible. 

A key issue for the aeronautical community is the proliferation of data link technologies. 

The existence of three different VHF data link technologies is a barrier to consensus 

building. However, several manufacturers have begun to address this issue through the 

production of multi-mode radios which are capable of supporting 25 kHz, 8.33 kHz and 

combinations of the VHF digital links. Hence a migration path 25 kHz to 8.33 kHz 

analogue for voice together with data modes progressing ACARS to VDL2 to VDL3/4 is 

technically possible. 

5.7.3 Possible use of Mode S SSR as a data link 

Mode S Secondary Surveillance Radar (SSR) was discussed in Section 3.3 as a means 

for provision of surveillance data. Mode S SSR has also been standardised to provide a 

communications link that is compatible with the ATN. The aeronautical community has 

given consideration in the past to use of this link for ATS communication services. The 

current status is that such use is not being actively pursued. The reasons for stopping 

development of Mode S data link included: 

Page 165

• achievement of required data rates and latency times for ATS were expected to 

require the use of relatively expensive ground based electronically scanning 

antennae; 

• alternative data links in the VHF and L-Band appeared to be becoming available. 

Whereas these reasons are still valid, the study team feel that it may be worth revisiting 

the possible use of Mode S: 

• Mode S provides a very secure data link compared with other modes; 

• the spectrum is available and expected to be capable of supporting the data 

load; 

• the system is well standardised and has been demonstrated; 

• a mandate for Mode S enhanced surveillance would provide a level of equipage 

that could be upgraded to support data communication on 1030/1090 MHz 

channels. 

Implementation of data services on 1030/1090 MHz channels would alleviate the load on 

the VHF spectrum. 

5.8 Replacement Technologies (radio, other or none) 


There are a number of replacement technologies for which there are emerging 

development plans but for which standardisation and demonstration is immature. 

Implementation dates and, in some cases, frequency assignments, are very uncertain 

and probably only possible from 2012 onwards. The identified technologies are: 

• New satellite services including: 

• Next Generation Satellite Service (NGSS); 

• Satellite Data Link Service (SDLS); 

• Broadband technology; 

NGSS is used to refer to the LEO/MEO systems such as Iridium and Globalstar whose 

primary purpose was mass communications market but which initially offered aviation 

service. ICAO is currently considering none of these systems. 

SDLS is a long term ESA research programme aim at demonstrating improvements to the 

current AMSS. During the course of this study EUROCONTROL have commenced work on 

NexSat which is a proposed L-band satcom solution which includes elements of the 

SDLS programme. 

Other companies have shown interest in providing new aeronautical mobile satellite 

communications systems both in the existing L-band allocation and at other frequencies 

such as Ka- and Ku-band which do not have an aeronautical allocation. Given the 

embryonic nature of these systems they have not been discussed in detail. 

5.8.2 Establishment of new satellite services 

This section considers two possible future satellite systems which could carry 

aeronautical traffic: 

• the next generation satellite system; 

• SDLS. 

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5.8.2.1 Next Generation Satellite System 

Next Generation Satellite System is a generic term referring to the potential aeronautical 

use of a number of emerging satellite system. The principal NGSS are: Iridium, ICO and 

Globalstar. As ICO and Globalstar no longer have plans to provide an aeronautical 

service, only Iridium is considered in detail. 

The nominal Iridium constellation consists of 66 satellites in low earth orbit (485 miles, 

780km) connected by inter-satellite links, and supported by a network of gateway earth 

stations. The system is designed to permit voice or data to reach its destination anywhere 

on Earth. The relatively short relay distance reduces the delay and enhances the quality 

of voice transmissions. 

The constellation has been deployed and in operation since 1998. Each satellite covers 

an area 4,000 km wide. Iridium is the only system to enable communications from one 

handset to another without the need to be downlinked through a gateway earth station. 

The satellites carry out on-board switching of the calls from the handsets. 

A link is transferred from cell to cell and from satellite to satellite as the spacecraft orbit 

(approximately one earth revolution per 100 minutes). The gateways are continuously 

linked to at least two satellites of the constellation. 

Iridium currently offers an aeronautical voice and data communications service. 

The characteristics of Iridium are summarised in Table 5-6 below. 


Service topology Point to Point Data and Voice services 

ATN compliance No An SNDCF could be developed 

Frequency band L-band, K-band, Ka- 

band 

RF Channels Four frequency subbands 

User Uplink 1616 – 1626.5 MHz (L- band) 

User Downlink 1616 – 1626.5 MHz (L- band) 

Feeder Uplink 29.1 – 29.3 GHz (Ka- band) 

Feeder Downlink 19.4 – 19.6 GHz (K- band) 

Inter-satellite 23.18 – 23.38 GHz (K-band) 

Transmitter power 1400W at source. EIRP is approx -70dBW/MHz. 

Modulation scheme QPSK 

Bit rate 2400 bps Voice and data services 

Channel access method FDMA, TDMA, TDD 



Dependencies None 

FCC Allocation No further action required, although frequencies 

are not restricted to aviation use. 

Table 5- 6 Characteristics of Iridium 

Page 167

5.8.2.2 SDLS 

SDLS is a proposed new satellite system designed to provide safety-related aeronautical 

communications. The system is being developed by ESA 23 . The idea is to use existing 

satellite and communications infrastructure as far as possible. SDLS represents a 

potential NGSS. 

It should also be noted that some of the characteristics designed here are design goals 

and may be different in a final system. 

The concept behind the design of the Satellite Data Link System (SDLS) is to provide 

improved satellite communications and surveillance services to offer: 

• Circuit Mode Voice for AOC. 

• ATS Specific Voice Service – replication of partyline and quasi-instant access 

by dedication of forward and return channels to each ATC sector. 

• All tuned receivers will constantly monitor traffic on the channel. 

• The partyline capability can be emulated by re-broadcasting the voice 

transmissions from aircraft via the forward channel. 

• Point-to-Point Data – ATN Compliant sub-network. 

• Polling Service - This ‘Polling Service’ allows the transfer between aircraft and 

ground of repetitive data and is similar to Automatic Downlinking of Aircraft 

Parameters (ADAP) services. It is proposed that the Polling Service be used to 

send: 

• Basic information - Position (latitude, longitude, altitude); Time; Figure of Merit; 

Flight ID. 

• Extended information - Ground Vector; Weather information; Projected profile; 

Short term intent; Intermediate intent. 

The SDLS system could use any of the satellite bands, but the L-band seems the most 

probable option. Currently there is no exclusive allocation, but priority access for 

AMS(R)S to a 10 MHz sub-band of the MSS band is granted through a footnote in the 

Radio Regulations. This could require the use of priority and pre-emption rules against 

other MSS uses of the band. 

Alternatively, dedicated usage of a sub-band could be decided. These issues are under 

consideration in ITU fora. By developing a system dedicated to AMS(R)S, the case for 

dedicated spectrum is likely to be easier to make and defend. The amount of spectrum 

needed for AMS(R)S is also under consideration, and is dependent on the range of 

applications to be supported, the final design of the system and the frequency re-use 

achievable. 

The SDLS system is still being defined. However it is proposed that SDLS would use 

QPSK modulation. The data rate would be 6.8 kbits/s per channel, and the vocoder rate 

for voice services would be 4.8 kbits/s per channel. These baseband channels would then 

be mapped onto a 1 MHz Code Division Multiple Access (CDMA) channel using a 

spreading code. 

23 EUROCONTROL have started the process of standardising an NGSS called NexSat 

which re-uses some elements of SDLS. 

Page 168

As the new satellite service will support civil aviation world-wide, ICAO SARPS will need 

to be developed. It is anticipated that much of the existing AMSS SARPS could be 

updated to include SDLS features. 

In addition, MASPS and MOPS will need to be developed. A further step will require 

standardisation in the avionics industry on equipment form, fit and function 

characteristics; this is traditionally the role of the AEEC. 

The GES operators will need a more detailed set of technical standards than is provided 

in the ICAO SARPS. For the current AMSS this level of detail was contained in the 

Inmarsat System Definition Manual (SDM). The SDM is used by GES and avionics 

manufacturers to produce equipment. This same level of detail will be required with 

SDLS. 

The characteristics of SDLS are summarised in Table 5-7 below. 


Service topology Uplink point-to-point, 

Downlink point-to-point 

ATN compliance Yes Additional specific service also provided. 

Frequency band Satellite bands (L-band, 

C-band, Ku-band) 

RF Channels 867 kHz bandwidth 

1545-1555 MHz for the downlink (from satellite to 

AES) 

1646.5-1656.5 MHz for the uplink (from AES to 

satellite) 

Modulation scheme QPSK Ground to air: Synchronous CDMA QPSK 

Bit rate 6.8 kb/s (4.8 kb/s 

vocoder) per channel 

Air to ground: Quasi Synchronous CDMA QPSK 

SDLS proposes to use a coding scheme using a 

convolution code (rate 3/4 and K=5) and, with a 

vocoder rate of 4.8 kbps rate (6.4 Kbps with error 

protection) leads to a link rate of 6.8 kbps 

including synchronisation overhead. 

Channel access method CDMA Forward channels are operated as slotted CDMA 

by each GES sending information requests to the 

controlled AES. A forward channel is allocated to 

one GES; this GES sends the information on a 

slotted burst, which is received by all AESs. Only 

the addressed AES recovers and processes the 

message. 

Return channels are operated either: 

Asynchronously: For the Polling Service 

(PS) services, a set of AESs share a CDMA 

coded channel for the return link in a slotted 

reservation scheme. Each AES has access to the 

return channel in a predefined slot burst or frame 

according to the message length which is 

indicated by the GES in the signalling information 

carried in the forward link. For other services, a 

set of AESs uses the same CDMA channel using 

slotted ALOHA. 

Synchronously: A TDMA CDMA channel 

is used. 

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Dependencies None known 

Yes Access to L-band spectrum for AMS(R)S is 

guaranteed under a Radio Regulation Footnote. 

The possibility of sharing arrangements within the 

MSS is still under discussion in ITU. 

Table 5- 7 Characteristics of SDLS 

Hence frequencies are available but would need 

to be shared by other uses i.e. existing Inmarsat 

AMSS 

5.8.3 Broadband systems 

Third Generation Mobile Communications (3G) has been developed by the 

telecommunications industry to support broadband personal mobile communications. 3G 

uses the Universal Mobile Telecommunications System (UMTS) protocols and Code 

Division Multiple Access (CDMA). Within 3G there are two proposed systems – WCDMA 

and CDMA2000. EUROCONTROL are actively developing the aviation use of 3G systems. 

This work has included simulations, bench tests and successful flight trials. 

The availability of the high bandwidth enables a variety of content to be transmitted, 

including voice, multimedia, internet and other sources of data. Additionally, 3G systems 

are intended to be highly compatible, offering services such as worldwide roaming. 

3G is an exciting technology which has the potential for offering a terrestrial broadband 

solution to aviation users, with the cost advantage of VHF solutions, and the bandwidth of 

satcom solutions. 

There are good reasons for adopting 3G/CDMA for aviation use: 

• It can provide a high-throughput data, voice, and video communication link 

available over continental airspace; 

• It has the potential of supporting a wide range of services including ATS, AOC, 

AAC and APC; 

• It will be compatible with the future satellite services, so that a seamless 3G 

service over continental and oceanic airspace will be possible; 

• The 3G technology is already developed and standardised and available in a 

mass market – therefore aviation standardisation should be very rapid, and 

system component costs will be low and experienced engineers widely available. 

There are different frequency bands in which the system could operate – the VHF 

(aeronautical band), 1 GHz, and 5 GHz are currently all being considered. The 1 GHz 

band has not yet been used in the prototype equipment. 

The throughput achieved to-date at 5 GHz with 5 MHz bandwidth is 1.5 Mbits per second. 

The system can accommodate both ATN and IP. Transmission delay is in the region of a 

few milliseconds. 

EUROCONTROL has simulated and performed flight trials with the Time Division Duplex 

(TDD) system. With the TDD system, the range is about 25 km. If using TDD, the system 

is limited to a range of 25 km at the nominal throughput - greater range is possible but 

only at the expense of throughput. 

Simulation and bench tests have been done for Frequency Division Duplex (FDD), with 

trials planned in the near future. With FDD, using either WCDMA or CDMA2000, range is 

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only power limited, and so the range can be of the order of 100-200 km. The size of a cell 

is therefore not an issue for FDD. 

A large part of the aeronautical standards that will be required for the 3D/CDMA system 

can simply be carried over from the current 3G standards. However, the aeronautical 

3D/CDMA standards will need to differ from the current 3G standards due to the different 

part of the spectrum being used, with consequent impact on the RF equipment. 

The aeronautical system has to accommodate a higher Doppler shift than the current 3G 

standards. This has to be compensated for in the system and will impact on the standard. 

ICAO has not yet been approached to produce ICAO SARPs. Also no EUROCAE/RTCA 

MOPS activity is yet being considered. 

An appropriate agenda item for WRC 2007 was adopted at WRC 2003, which inter alia 

requires consideration of spectrum for the system. However the system is expected to be 

able to co-exist with MLS in the MLS band with no problems. The system may also use 

the RadioLAN band. 

The characteristics of emerging broadband systems are summarised in Table 5-8 below. 




ATN compliance Yes The system can be ATN compliant and/or IP 

compliant. 

Frequency band 5 GHz (C-band) Could also operate in the 2 GHz and/or VHF 

aeronautical band 

RF Channels Single 5 MHz channel 

EIRP 40-50dBW. Specific value for Boeing Connexion. 

Modulation scheme QPSK 

Bit rate 1.5 Mbps 

Channel access method CDMA With Frequency Division Duplex (FDD) or Time 

Division Duplex (TDD) for duplex transmission 



Dependencies 

Frequencies not yet 

assigned 

Text is currently being considered for an agenda 

item in WRC 2003 or 2006 for consideration of a 

spectrum allocation for the system. However the 

system is expected to be able to co-exist with 

MLS in the MLS band with no problems. The 

system may also use the RadioLAN band. 

Table 5- 8 Characteristics of Emerging Broadband Systems 

5.9 Allocation Sharing Opportunities 

5.9.1 Gatelink 

The concept of high bandwidth communications with aircraft at or near the gate is not 

new. Over the years a number of technologies have been considered including the use of 

fibre-optic links, microwave links and more recently the currently emerging Wireless Local 

Area Network (WLAN) solutions. 

Page 171

A number of airlines and equipment manufacturers have shown considerable interest in 

the Gatelink concept. In particular the Rockwell-Collins Integrated Information System 

(I 2 S) programme supports the integration of Gatelink to multiple aircraft systems, a file 

server and a secure interface unit to enable safety and non-safety applications to be 

supported. 

British Airways, Swissair and Condor have all been involved in trials of Gatelink systems. 

In 2000, EUROCONTROL published an in depth study into Wireless Airport 

Communications Systems (WACS), which considered potential WLAN solutions for 

Gatelink. The material in this section is largely taken from the published reports. 

The three main Wireless LAN candidate technologies which could be used for Gatelink 

are: 

• Systems operating at 2.4 GHz conforming to IEEE 802.11b standards: 

• GHz FHSS / DHSS 

• GHz DSSS HDR 

• High Performance Radio Local Area Network (HiperLAN) according to ETSI 

HiperLAN standards: 

• 5.2 and 5.8 GHz HiperLAN/1 and HiperLAN/2 

• 17.1 GHz HiperLAN 

• Systems conforming to Digital European Cordless Telecommunications (DECT) 

standards. 

Trials already conducted have shown that 2.4 GHz technology is usable in an airport 

environment using either DSSS or FHSS modulation. Systems operating at 5 and 17 GHz 

are less well developed. While these systems have the potential to offer improved data 

throughput, they do so at the expense of usable range. 

Gatelink offers a huge potential for Airline Operational Communications (AOC), Airline 

Administrative Communications (AAC) and Air Passenger Correspondence (APC). The 

role in Air Traffic Control is less clear. 

The deployment of Gatelink to support non-safety services is likely to be driven by local 

business cases and may support emerging Collaborative Decision Making (CDM) 

applications and applications involving the (re)allocation of CFMU slots, but the additional 

burden of supporting ATC is likely to increase costs and timescales. The adoption of a 

mature system, some years after deployment, to support ATC in the presence of 

alternative communications means should be considered. 

Systems operating at 2.4 GHz can either use Frequency Hopping Spread Spectrum 

(FHSS) or Direct Sequence Spread Spectrum (DSSS) modulation schemes. Current 

FHSS systems have a data rate of between 1 and 2 Mbps. Current DSSS systems have a 

data rate of 2 Mbps, but future systems are planned with a rate of up to 11 Mbps. 

The characteristics of Gatelink are summarised in Table 5-9 below. 




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ATN compliance No Current systems being implemented are based 

on TCP/IP and are not ATN compliant. The ICAO 

ATN Manual contains provisions for previous 

Gatelink solutions – but not WACS as considered 

here. 

Frequency band 2.4 GHz, Other potential systems at 5.2 GHz, 5.8 GHz and 

17.1 GHz 

RF Channels Single channel 

Modulation scheme Frequency Hopping 

Spread Spectrum 

(FHSS) and Direct 

Sequence Spread 

Spectrum (DSSS) 

Bit rate 2.4 GHz FHSS: 

Current systems have a 

rate of 1-2 Mbps 

2.4 GHz DSSS: 

Bit rate on current 

systems is 2 Mbps – in 

future this may be 

increased to 11 Mbps 

Other Systems: 

5.2 and 5.8 GHz: 

Bit rates of up to 20 Mbps are expected 

17.1 GHz: 

Bit rates of up to 150 Mbps are expected 

Channel access method CSMA-CA, TDMA Systems complying with IEEE 802.11a (5 GHz 

systems) and 802.11b (2.4 GHz systems) use 

Carrier Sense Multiple Access with Collision 

Avoidance (CSMA-CA) 



Dependencies None 

Frequencies allocated 

worldwide and available 

Table 5- 9 Characteristics of Gatelink 

HiperLAN systems (5 GHz systems) use Time 

Division Multiple Access TDMA 

Frequencies at 2.4 GHz are available worldwide 

for use by WACS/Gatelink and do not require a 

licence. 

At 5.2 GHz, there are worldwide frequencies 

available which do not require a licence. 

At 17.1 GHz, allocation is worldwide but users 

require a licence for a particular geographical 

area. 

5.9.2 Transfer to commercial data links 

The increase in requirements for passenger services (IFE etc) drives the provision of new 

high data rate links (particularly for uplink services). An opportunity for ATS 

communication is to piggy back on top of these services. The advantage is that 

passenger services will be commercially driven with separate business cases providing a 

low marginal cost route for ATS. The drawbacks include the lack of precedent for sharing 

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links with non-safety critical services and the general reluctance in the industry to 

consider such a route. A further disadvantage is that such links provide only a low data 

rate downlink. 

5.9.2.1 AMSS 

One example of a future service is a development of AMSS. 

Inmarsat have recently introduced the Swift64 high speed data link for cabin services 

(not ATM). This service should provide channels with up to 64 kbit/s, although in trials 46- 

57 kbps was obtained. 

Honeywell and Thales have a prototype Inmarsat-approved Swift64 system which is due 

for production in 2003. The airborne system consists of a new HS-600 unit added on to a 

conventional Honeywell MCS-6000 Inmarsat system. The system is currently 

asynchronous, with 64 kbps (Swift64) data delivered to the aircraft and a Ku-band link for 

data delivery from the aircraft. 

The next generation Inmarsat-4 satellites are due for launch next year. These satellites 

will be able to support broadband communications including 3G with channel rates in 

excess of 420 kbits/s. 

5.9.2.2 Boeing Connexion System 

The Boeing Connexion system is a satellite-based data communication system that will 

provide broadband data services such as internet, TV, and radio to aircraft using leased 

Ku-band satellite transponders. The system will operate in the 14.0-14.5 GHz band for 

aircraft-to-space links and in portions of the 11.2-12.75 GHz band (depending on region) 

for space-to-aircraft links. 

The system will offer uplink rates of up to 10 Mbps per aircraft, and downlink data rates of 

up to 1.5 Mbps. Thus the system is highly asymmetrical, the uplink offering a far higher 

throughput than the downlink. Airplane passengers will access the system using a laptop 

computer, PDA or seatback terminal. 

Boeing has total control over the system. The system gained FAA certification in May 

2002, and certification for use in UK airspace in July 2002. 

It may be difficult to modify the Boeing system to provide ATS services, with the required 

guarantees of reliability, availability, safety, and security. 

The proposed system is composed of four segments: 

• a space segment which consists of leased FSS transponders 

• an airborne terminal segment that consists of satellite terminals installed on 

multiple aircraft 

• a ground earth station segment which consists of one or more FSS Earth 

stations 

• a Network Operations Center (NOC) segment that controls the aggregate 

emissions of the system in order to prevent interference to other co-frequency 

systems. 

Page 174

Figure 5-2: Boeing Connexion system segments 

The ground earth station segment is connected to the NOC segment with redundant highspeed 

data connections. Multiple ground earth stations and NOCs may be included in the 

system for redundancy. 

5.9.2.3 Uplink 

The connection from the ground up to the satellite will employ up to four transponders 

(carriers), with uplink data rates of between 5 and 10 Mbps per transponder. The system 

uses a direct sequence spread spectrum (DSSS) waveform to minimize interference. 

Figure 5-3: Data uplink via transponders (carriers) in Boeing Connexion system 

Each aircraft will be capable of receiving four transponders from the satellite for a total 

data rate of between 20 and 40 Mbps. Each forward link signal transmitted to the aircraft 

carries an IP packet stream of video and data content. 

Packets are unicast, multicast or broadcast to aircraft in the transponder coverage region. 

An onboard router accepts only those packets addressed to that aircraft and routes the 

packets to passengers via the onboard LAN. 

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Live TV content and pushed web page content (most popular web pages) are multicast to 

aircraft. The web content is cached in an onboard server for rapid availability to 

passengers. 

The satellite links will only be used to convey content that is not available from the 

onboard server. All e-mail will be received and transmitted in real-time over the satellite 

links. 

5.9.2.4 Downlink 

As on the uplink, the system uses a direct sequence spread spectrum (DSSS). The 

system downlink uses demand assigned multiple access (DAMA) to adjust the transmit 

data rate from the aircraft (16 Kbps to 1.5 Mbps) to match the aircraft demand. 

Figure 5-4: Data downlink via transponders (carriers) in Boeing Connexion system 

The number of DSSS chips per bit is adjusted to maintain a nearly constant chipping rate 

of 90% of the transponder bandwidth. Multiple aircraft simultaneously access each return 

link transponder using different pseudo noise (PN) code phases (similar to CDMA). The 

system experiences some loss of performance (about 1 dB) due to self-interference from 

asynchronous aircraft transmissions. 

Airborne antenna design 

Boeing will initially offer airlines an electronically scanned phased array antenna that 

mounts flat on the crown of the aircraft. The antennas cause some additional 

aerodynamic drag to the aircraft. 

The antennas will be mounted on top of the aircraft fuselage and separated from each 

other by approximately 1.25 meters to prevent self-interference. Prototype transmit 

antennas are currently being fabricated by Boeing, and receive antennas have been flight 

tested for a number of years. 

Both phased array antennas can be electronically scanned to about 70 °. This scan angle 

performance is sufficient for initial operation but is inadequate for busy higher latitude air 

routes in North America, Europe and the North Atlantic. 

A different antenna design that can scan down to the horizon is required for operation at 

latitudes above 60°. Such antennas typically protrude more above the top of the aircraft 

Page 176

and incur additional aerodynamic drag. Boeing is working with suppliers to develop high 

performance antennas that can scan down to the horizon. 

5.9.2.5 Deployment 

The system will use leased Ku-band transponders on geostationary satellites to provide 

an initial service. Boeing plans to grow the system capacity with customer demand by 

leasing additional transponders. 

Existing Ku-band satellites can provide coverage over most continental landmasses. 

However, transponder coverage is currently not available over popular trans-oceanic air 

routes. Boeing plans to provide a North Atlantic air route service using transponders that 

were recently added as a “piggy-back payload” to an in-production commercial satellite. 

A CONUS service is planned for late 2001, with expansion to the Atlantic & Pacific 

Oceans, Europe, Canada and South/Central America in 2003. A service to Asia and 

Africa is planned for 2004. 

The characteristics of Boeing Connexion are summarised in Table 5-10 below. 


Service topology Point-to-point The major aim of the system is to provide video 

(television) and high bit rate transmission (web 

access using cache mechanism on board aircraft) 

from ground to air in a multicast or broadcast 

mode. 


Frequency band Service Link: 

RF Channels 

Satellite to AES: 11.2- 

12.75 GHz 

AES to Satellite: 14.0- 

14.5 GHz 

Feeder Link: 

EIRP 46.2dBW. 

Satellite to GES: 19.3- 

19.7 GHz 

GES to Satellite: 29.1- 

29.5 GHz 

Modulation scheme Direct Sequence 

Spread Spectrum 

(DSSS) 

To a lower extent the system could also support 

point-to-point communication. 

The basic packet standard is IP compliant. 

It is not a basic service but an ATN packet could be 

embedded in an IP packet. 

Ku band used also by VSAT. Exact allocation 

depends on the ITU region considered. 

Page 177


Bit rate 5-10 Mbps uplink 

Channel access method 



16 kbps – 1.5 Mbps 

downlink 

Frequency usage 

currently granted in 

US, Canada, UK, & 

Germany. 

Dependencies Availability of Ku 

transponders on board 

satellite. 

Table 5- 10 Characteristics of Boeing Connexion 

Frequency usage needs to be granted by the 

country where the service is intended to be 

operated. 

The service is totally under the control of Boeing 

5.9.3 Other sharing issues for further consideration 

A lot of aviation traffic, especially GA, takes place only during the day, either due to 

restrictions on visibility or limitations in the times over which airports can operate (no 

flights are allowed in or out of Heathrow overnight for example). It is therefore possible 

that if a suitable sharer could be identified, some of the aeronautical communications 

channels could be re-used for other purposes at night. 

5.10 Possible Overall Spectrum Efficiency Improvements 

The possible measures for improved spectrum efficiency identified in this section are 

summarised in Table 5-11 below. 

Development Impact on Spectrum Comment 

Operational requirements 

Increased airspace capacity through new 

operational concepts including 

automation, conflict free trajectories and 

increased delegation to pilot rather than 

through systemisation 

Regulatory 

Decommission VOR and make more 

VHF spectrum available for 

communication 

Optimisation of current analogue voice services 

Encourage move to 8.33 kHz channel 

spacing 

Introduction of UHF 8.33 kHz spacing in 

NATO band 

Optimisation of services using current digital links 

Potential for a reduction in 

demand on VHF spectrum 

through a reduction in the 

number of air traffic control 

sectors 

More efficient use of existing 

spectrum (i.e. decommission 

of increasingly redundant 

system and replacement with a 

useful system) 

Significant reduction in need 

for spectrum since current 

channelisation is divided into 

three 

Potential for releasing 

spectrum for other applications 

Some early gains through initial 

automation but wholescale 

concept change needed from 

(2012+) 

Possible barriers include the 

terms of NATS operating licence 

and the need to maintain support 

for VOR operations 

At high altitude requires 

completion of RICE infrastructure 

and a solution for large sectors 

At low altitude requires GA 

equipage 

Costs an issue but if backwards 

compatibility ensured may speed 

up introduction 

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Encourage move of HF voice to HFDL More efficient use of current 

HF channels 

Use Satcom to replace HFDL High cost of satellite 

communication makes this 

unlikely in the short term 

Transfer ACARS to VDL2 10 fold increase in VHF 

channel utilisation 

Move ATIS to digital ATIS on VDL Mode 

2 

Move some ATS controller pilot dialogue 

to data on VDL Mode 2 

Investigate more efficient ways of 

allocating analogue channels as 

communications move to data 

Free up UHF spectrum by moving 

surface vehicles to VHF 

Remove requirement for some 

VHF voice channels 

Little effect on spectrum (in 

fact need spectrum at top of 

voice band) 

A key issue – as voice moves 

to data, voice channel 

utilisation becomes very low – 

how can this be taken 

advantage of? 

Makes it possible to introduce 

new services into UHF 

spectrum 

Wholescale movement of current analogue services to digital 

Move voice to VDL Mode 3 Provides up to 4 voice 

channels per 25kHz channel 

Move communication to VDL Mode 4 More efficient than current 

VHF communication 

Reconsider Mode S datalink Potential to introduce data link 

into an existing part of the 

spectrum reducing overload 

elsewhere (i.e. in VHF 

spectrum) 

Establish new satellite services including 

NGSS and SDLS 

Introduce broadband services in existing 

spectrum (VHF or L band) 

Not possible to determine at 

this stage 

Potential for highly efficient 

system in VHF band 

Share services over WiFi (Gatelink) Aviation benefits from 

commercially allocated 

spectrum, reducing pressure 

on spectrum elsewhere 

Piggy back ATS services on to satellite 

commercial services (e.g. future AMSS, 

Boeing Connexion) 

Not possible to determine at 

this stage 

Note that VDL 2 is not 

particularly efficient for two way 

point to point communication 

because of its random access 

protocol and need for guard 

bands 

Will become possible as VDL 

Mode 2 is introduced 

VDL2 not a long term solution for 

CPDLC because of random 

access protocol and no support 

for priority 

Open ended requiring more 

investigation 

Currently happening at some 

airports (e.g. Heathrow) 

Unlikely to offer many 

advantages over 8.33kHz 

channelisation and hence 

implementation considered 

unlikely 

Spectrum efficiency still to be 

proven 

Mode S data link has been 

considered and rejected in the 

passed by the community. 

However, there is some 

possibility that it could be reconsidered 

on the back of the roll 

out of the Mode S surveillance 

ground infrastructure. 

Development should emphasise 

spectrum efficiency 

New system, implementation in 

VHF requires clearing out of old 

VHF services 

In L band, would require proof 

that services could be provided 

at an attractive price 

Airport authorities actively 

planning to expand WiFi services 

Driven by reduced marginal 

costs. 

Mixing safety critical and nonsafety 

critical on the same 

Page 179

Table 5- 11 Measures for Improved Spectrum Efficiency 

channel – is this really such a 

problem? 

The following is proposed as a strategy for improving overall spectrum efficiency for 

aeronautical communication: 

• short term measures (to 2005): migrate voice services to 8.33 kHz spacing and 

decommission VOR navaids. 

• medium term measures (2005 to 2012): encouraging the aeronautical community 

to bring demand for new voice channels under control through the introduction of 

more efficient air traffic control concepts such that the demand begins to level 

off; 

• long term measures: establish spectrum efficient solutions for air/ground 

communication coupled with clearing out of voice channels. 

The next section states recommendations and explores the socio-economic issues 

associated with this strategy. 

5.11 Conclusions and Recommendations 


This Chapter of the Report has reviewed the options for the evolution of aeronautical 

communication. The evolution is driven by two key factors: 

• the saturation of the VHF band; 

• a steadily rising demand for ATS services and a potentially very large increase in 

demand for non-ATS services. 

Finding a way forward is limited by the difficulty of obtaining widespread fleet equipage for 

any particular solution. Furthermore, equipment costs tend to dominate any 

implementation strategy and spectrum considerations are given little consideration. 

Hence it is important that Ofcom work to ensure that future solutions are spectrum 

efficient. Given the very long lead times for implementation, it is important now to ensure 

that correct implementation paths are chosen. 

5.11.2 Socio-economic issues (general) 

The technology necessary to support the short and medium elements of the strategy is 

already available. Similarly, the changes to air traffic management concepts necessary to 

begin the process of migrating voice to data have already been demonstrated as part of 

the EUROCONTROL Link 2000+ programme. The barriers to progress are essentially 

socio-economic. The key factors are described below. 

Cost of fleet upgrade: Any change in technology will require a change in the equipment 

carried by aircraft. The business sector facing the highest costs is the Air Transport 

aircraft operators. Costs escalate for many reasons including: 

• the need to produce equipment that is certified for carriage on aircraft without 

detriment to other safety of life aircraft systems 

• the possible requirement to install new antennas 

• the need to take the aircraft out of service for upgrade to take place 

• small volume specialised market leading to inherently high unit costs 

Page 180

An illustrative example of airborne costs for point-to-point technologies is given in Table 

5-12 below (based on work carried out for the European Commission). 

Costs in £ HFDL VDL2 VDL3 VDL4 

Baseline assumed HF voice or no 

HF 

Hardware 

No CMU 

previously 

installed 

CMU previously 

installed 

Cost of transceiver 41,600 34,800 39,800 31,700 

Antenna (x 2) n/a n/a 1,400 1,400 

Upgrade of Radio Control Panel 

(RCP) x 2 

Communications Management Unit 

(CMU) 

Upgrade of Communications 

Management Unit (CMU) 

Upgrade of Data Link Control 

Display Unit (DCDU) 

Integration, installation & 

certification 

n/a n/a 13,400 n/a 

n/a 33,100 n/a n/a 

n/a n/a 5,600 5,600 

n/a n/a 4,200 n/a 

Installation kit(s) 2,100 3,400 3,000 2,300 

Service bulletin 4,200 6,800 6,000 4,700 

Man-hours (80 euro/hour) 2,100 3,400 3,200 2,300 

Total initial costs per aircraft (1 

transceiver) 

Yearly maintenance costs per 

aircraft (1 transceiver) 

50,000 81,500 76,600 48,000 

4,200 6,800 6,400 4,700 

Page 181 

Point-to-point 

CMU previously 

installed 

Table 5- 12 Summary of Airborne Costs for the Point-to-Point Technologies 

It can be seen that costs can be of the order of £82k per aircraft, amounting to some 

£900M for the European AT fleet (assuming 11,000 aircraft). These costs are for 

retrofitting existing aircraft. Costs for new aircraft are generally much lower although, as 

discussed later in this section, the rate of introduction of new aircraft is very slow. 

Cost for GA users: Compared with the AT fleet, the costs for GA users are much lower. 

Some manufacturers are currently proposing multimode radios with a capability for 8.33 

kHz voice, VDL Mode 2 and other VDL modes at a cost of between £1.5k and £3.5k. 

Given market volume, the prices may be even lower. 

Unfortunately, such costs are prohibitive to many GA operators and hence there is 

considerable resistance to change, particularly where that change results from a 

requirement to be interoperable with AT class aircraft and where there is no tangible 

benefit for GA.

Cost of ground infrastructure: The cost of ground infrastructure can also be a 

significant barrier to change. The cost of a European network of VHF digital ground 

stations is illustrated below. 

The costs include the ground station (transceiver + antenna), but exclude the network and 

ATC centre upgrade costs. 

Costs in £ HFDL VDL2 VDL3 VDL4 

Baseline assumed Existing HF 

voice ground 

station 

Existing ground 

station site 

Existing ground 

station site 

Page 182 

Point-to-point 

Mode S 

Elementary 

Surveillance 

Cost of ground station 33,800 42,300 105,600 77,500 

Installation 6,800 8,500 21,100 15,500 

Total initial cost per ground 

station (1 transceiver) 40,600 50,800 126,700 93,000 

Yearly maintenance costs per 

ground station (1 transceiver) 3,400 4,200 10,600 7,700 

Number of ground stations required 

in Europe 20 150 150 150 

Total ground station costs (1 

transceiver) 0.8 million 7.6 million 19.0 million 14.0 million 

Table 5- 13 Summary of Ground Costs for the Point-to-Point Technologies 

Slow update cycles: The high costs of equipment, in an industry operating on low 

margins, leads to a resistance to change and, in part, explains slow update cycles. 

Operators will use airborne equipment for as long as possible to extract the greatest value 

for money. 

A second issue is the slow update rate of aircraft. The rate of introduction of new aircraft 

is typically less than 5% of the overall fleet per year. Hence, whereas the introduction of 

new technology is much cheaper when purchased with a new airframe, the reality is that, 

if there is any urgency about introducing new technology (i.e. faster than 10 years), the 

appropriate costs are retrofit costs which as illustrated above can exceed £80k for a 

typical airframe. 

A further contributory factor is the time taken to reach consensus on a particular next 

step. It took time for operators to accept the upgrade to 8.33 kHz and the next major 

upgrade, to Mode S enhanced surveillance, is still poorly accepted on the basis that there 

is no clear value for money. 

A further example of lack of consensus is in the choice of future air traffic concept. There 

is consensus that something needs to be done in order to provide sufficient capacity to 

meet airspace demand but little consensus as to the what. Up until now, spectrum 

efficiency has not been a major issue in consideration of a future direction for concept and 

technology. 

Safety of life communication/public perception: Aeronautical communication provides 

a safety critical service and the community has generally required the communication to 

be ring-fenced into its own spectrum allocation. This has lead to a resistance to sharing 

with other modes and leads to an unwillingness to piggyback onto more commercially 

focussed services (such as passenger communication).

Illustrative value of spectrum calculations: In a recently published report on spectrum 

pricing, the potential to apply administrative incentive pricing (AIP) to aeronautical 

spectrum is considered. The model used is to relate the marginal value of spectrum to the 

cost of upgrade. The approach was used to provide three marginal values for the 

migration to 8.33 kHz. 

The same approach is used in the illustrations that follow. Also included is a very simple 

indication of the “value” of the spectrum as a means of assessing if there could be a 

business case for adopting spectrum efficient technologies. 

The illustrations are based around the emerging strategy for aeronautical communication 

shown in the figure 5-5 below. 

Figure 5-5 Strategy for Aeronautical Communications 

This is the EUROCONTROL strategy for data communication and surveillance. For data 

communication the process involves the phasing out of ACARS for digital transmission of 

AOC data with a migration to VDL Mode 2. There is then a transition to a more spectrally 

efficient VDL mode (VDL M3 or M4) followed by a next generation system, either satellite 

or terrestrially based. Simultaneously, there is an introduction of other communication 

means to support ADS-B (1090 ES followed by VDL Mode 4). The early stages of the 

communication strategy apply to commercial operator data. The later stages include the 

transfer of ATS voice services to data. 

In parallel with the illustration (Figure 5-5) above, a migration of voice services to 8.33 

kHz is expected. The study team believe that it is also vitally important that when the next 

generation systems are introduced, there is an equivalent wholescale reduction in the use 

of VHF voice channels so that the spectrum can be re-used for data and other services. 

Based on Figure 5-5 above, the following “spectrally efficient” illustrations are provided: 

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• migration to 8.33 kHz spacing for voice services increasing spectrum efficiency 

by a factor of between 2 and 3. 

• migration of a VDL Mode 2 network to a more efficient solution within the VHF 

band increasing the efficiency for transmission of AOC data by a factor of 

between 2 and 3 on top of the improvement by a factor 10 achieved in the 

migration ACARS to VDL Mode 2. 

• migration of voice services to data within or outside the VHF band with an 

accompanying reduction of voice services. 

5.11.3 Short term measures 

Recommendation 5.1: An urgent first measure is to promote the migration to 8.33 kHz 

spacing in the VHF band. This measure will alleviate the immediate shortage of VHF 

spectrum and facilitate the establishment of digital services. 



cover a wide geographic area. For low level implementation, the barrier is GA equipage 


Ofcom should work with the CAA to encourage the implementation of 8.33 kHz spacing 

including accelerating the necessary changes to the NATS infrastructure and considering 

the issue of, and a possible means of stimulating, GA equipage. 


Firstly consider the value of VHF spectrum to NATS operations. For illustration purposes, 

it is assumed that NATS annual turnover from airline fees is of the order of £500M per 

annum with typically 8% profit before tax 24 . All spectrum allocated to the communication, 

navigation and surveillance infrastructure is required to support this level of turnover. 

Taking the case of VHF voice communications, it will be assumed there are 

approximately 500 25 kHz channels dedicated to air traffic control. Each channel is 

therefore supporting revenue of £1M per year and profit before tax of about £80k per 

year. 

Since each 25 kHz voice channel could be divided into three, NATS has the potential to 

generate an additional £160k per year from a 25 kHz channel by moving to 8.33 kHz 

channelisation. It is unlikely that an increase of efficiency by a factor 3 could be achieved 

because of re-use distance considerations. Assuming more conservatively that the 

increase in efficiency is a factor of 2, the additional profit is £80k per year. 

Hence there is a clear motivation for NATS to secure sufficient spectrum allocation to 

support the growth of air traffic. 

As indicated earlier in this section, there are a number of barriers to converting to 8.33 

kHz: 

• NATS must update its infrastructure 

• the GA fleet must update to support 8.33 kHz (it is assumed that AT class aircraft 

have already converted to 8.33 kHz). 

24 

These are illustrative figures, believed by the study team to be realistic. The figures 

have not been validated by NATS. 

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An illustrative calculation of the costs associated with converting to 8.33 kHz has been 

provided in a recent study for Ofcom 25 . This is a good general illustration but a number of 

comments can be made: 

• An upgrade cost of £845 per aircraft is quoted. It is very doubtful that the change 

could be made by an upgrade of current radios (as is assumed in the recent 

study for Ofcom) – rather, the existing radio would have to be disposed of and 

replaced with a new radio. In order to introduce 8.33 kHz, all aircraft operating in 

a particular region must be equipped. However, the refresh time for radios in GA 

is likely to be even slower than AT class. A GA pilot will not change a radio 

unless absolutely necessary and possibly not within the lifetime of the aircraft (15 

years at least). Hence, 8.33 kHz could only be introduced at low altitude if there 

is requirement to change radios and possibly additional funding to make this 

possible. Hence, the illustrative calculation should include the full price of the 

8.33 kHz radio (£3,225) and not the marginal difference between a 25 kHz and 

8.33 kHz radio (i.e. we rely on wholescale change of the fleet rather than a drip 

feed via new aircraft). 

• The quoted value of £75,000 for upgrade of a ground station is accepted 

assuming it was sourced from NATS. However, the distinction between 8.33 kHz 

and 25 kHz equipage is not understood. A particular new ground radio would 

support both channel arrangements. Hence, in the illustration, all ground stations 

would have to be converted. 

• NATS will also incur additional costs to convert its voice network to handle 8.33 

kHz. The costs are estimated at £10M although this figure has not been 

validated. 

• An estimated cost of £20,000 for each non-ATC station upgrade is felt to be a 

reasonable estimate given the non-safety critical nature of the services 

(equivalent to the cost of a TETRA PAMR transceiver). 

• The report quotes 6,200 aircraft as requiring upgrade. Fleet data for the UK 

indicates that this may be higher (up to 8000) although in the table below 6,200 

has been used. 

A revised table (5-14) of marginal cost following the same method with revised input costs 

is therefore: 

Cost element Cost 

ATC station upgrade + Network conversion £45.25m 

Non-ATC station upgrade £28.32m 

Aircraft station upgrade £20.0m 

Total cost £93.57m 

Annualised total £9.99m 

Cost per MHz £1.05m 

Cost per 25 kHz £26,200 

Table 5- 14 Marginal Cost for conversion to 8.33 kHz 

25 “An economic study to review spectrum pricing”, INDEPEN, Aegis systems and 

Warwick Business School, February 2004. 

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The key is to provide a phased transition: 

• fit ground station upgrades into the normal replacement cycle 

• choose regions to convert to 8.33 kHz and, if possible, provide assistance to the 

affected GA operators. Note that this might involve providing direct funding 

assistance to GA operators in return for acceptance by that community of a 

mandate to equip by a certain date. Other options include waiting for natural fleet 

renewal, a process that could take at least 15 years, or simply issuing a 

mandate, in which case all resultant costs are placed on the GA community. 

5.11.4 Medium term measures 

Possible medium term measures include: 

• encouraging the aeronautical community to bring demand for new voice 

channels under control through the introduction of more efficient air traffic control 

concepts such that the demand begins to level off; 

• transferring existing ACARS data to VDL Mode 2 

• freeing up VHF spectrum by decommissioning VORs. 

The control of demand requires NATS to employ strategies to provide additional airspace 

capacity that rely on techniques other than systemisation. In the next 4 years, NATS will 

have implemented much of its Mode S programme. This in turn provides the data 

necessary to implement some initial controller tools with a resultant increase in capacity. 

In the longer term, concepts based on a greater delegation to the pilot offer the potential 

to provide much greater airspace capacity without the need to introduce more sectors. 

Planning for such a concept is needed now. However no specific recommendation for 

Ofcom is made on this issue since it is seen as primarily an issue for the aeronautical 

community only. 

Recommendation 5.2: The introduction of VDL2 provides an opportunity to transfer 

existing ACARS traffic with a resultant increase in spectrum efficiency by a factor of 10. 

ATIS services should also be transferred making possible the re-allocation of some of the 

spectrum. The introduction of VDL2 also provides an opportunity to introduce some 

controller-pilot dialogue services, which are unlikely to result in a decrease of voice 

channels but provide a means of preparing for a wholescale transfer in the longer term. 

Where parts of the VHF band are to be used for AOC and commercial services in 

general, Ofcom should consider administrative incentive pricing to encourage efficient 

usage. 


This illustration is based on the operations of SITA which are described below. 

The SITA AIRCOM Datalink Service today comprises over 650 VHF ACARS stations 

deployed in over 165 countries. The SITA VHF AIRCOM Datalink service has over 120 

airlines/aircraft operator customers which have over 5,000 VHF ACARS equipped aircraft 

that use the service on an almost daily basis, exchanging on average 11.5 million kilobits 

per month. Over sixty percent of this traffic is exchanged over the European region where 

the service operates on 3 frequency channels. 

Over 2,000 (representing seventy customers) of these aircraft are also equipped with 

SATCOM avionics that exchange, on average, over 2 million kilobits per month. 

Since the early 1990’s an increasing number of air traffic service providers have started to 

use the AIRCOM Datalink service to exchange Air Traffic Service related application data 

which currently accounts for around 5% of the total traffic exchanged over the service. 

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A VDL2 channel will provide 10 times the capacity of the existing VHF ACARS channel, 

i.e. for Europe, where approximately 7 million kilobits are exchanged monthly today over 

3 VHF channels, the effective capacity will be increased to 70 million kilobits which SITA 

believes will more than adequately meet foreseen increases in AOC communications as 

well as the requirements for ATS applications. 

If the number of channels is increased from 3 to 6 this would effectively double the 

capacity, i.e. enable the exchange of 140 million kilobits per month. 

The price per kilobit of data exchanged is difficult to obtain and subject to commercial 

agreements between SITA and individual airlines although aeronautical cost benefit 

cases have used an estimated figure of £0.046 per kilobit. This values the revenue from 

SITA’s current European business on ACARS at £1.3M per year per channel. The move 

to VDL Mode 2 has the potential to increase the revenue to £13M per year per channel 

for the European service. Assuming that SITA operate at10% profit before tax, each 

channel has potential value of £1.3M per year. 

Hence, assuming demand for data services exists and, experience in other fields 

suggests that it does (although not necessarily at the relatively high data costs used by 

SITA); there is strong commercial desire to use any spectrum that could be freed up in 

the VHF band. 

An early use of digital links might be for the uplink of aircraft information. Such an uplink 

might provide a valuable service to general aviation users which, since the information 

could include the location of restricted areas, could enhance safety of both GA and AT 

class aircraft. 

Assuming that GA operators would be prepared to pay an annual subscription of £300 26 , 

that 10% of the 20,000 GA fleet in the UK take up the service and that the basic 

subscription service requires one 25 kHz channel, then the revenue generate per channel 

is £600,000 per annum. Assuming the service is provided at a 10% profit rate, the value 

generated is £60k per annum. 

Clearly there is a strong potential to unlock spectrum for commercial use. The obvious 

mechanism is a concerted drive to 8.33 kHz channelisation. The barriers are a) the need 

to modify ground infrastructure and b) providing interoperability with GA. 

Taking the example of GA first, the cost of equipping GA with new radios might be £20M 

assuming 20000 aircraft, and £1000 per radio. The data value of 10 channels could be as 

high as £20m per year. 

It is important that the digital services are provided as efficiently as possible. Although 

VDL Mode 2 provides a considerable improvement compared with ACARS, it is still not 

particularly efficient. Studies have indicated that the effective data throughput of other 

VDL modes (3 and 4) could be between 2 and 3 times higher than that of VDL Mode 2. It 

is therefore possible to consider the use of AIP to encourage take up of more efficient 

data modes. 

There are at least two possible scenarios: 

• A: allow airline choice at first adoption and support both modes within the ground 

infrastructure 

• B: allow VDL Mode 2 to predominate and then upgrade to the next mode. 

26 This figure is based on the study team’s judgement and has been made for illustration. 

The figure has not been validated with GA users. 

Page 187

There is little cost difference between the various VDL modes; hence there is no airborne 

operator marginal cost. However, the ground network will need to support two modes, 

probably via multimode ground equipment located at the same ground station. It will be 

assumed that ground station conversion costs are similar to those quoted above for 

conversion to 8.33 kHz, namely £75,000. Assuming that there are 30 ground stations 

providing network services in the UK, the total cost is therefore £2.25M. Assuming that 

the network supports 4 channels and that a threefold increase in efficiency is obtained, 

the marginal cost table becomes (Table 5-15): 

Cost element Scenario A 

ATC station upgrade + Network conversion N/A 

Non-ATC station upgrade £2.25m 

Aircraft station upgrade 0 

Total cost £2.25m 

Annualised total £240k 


Cost per 25 kHz £60k 

Table 5- 15 Revised Marginal Cost Table 

Although the cost per 25 kHz channel is relatively high, the revenues that could be 

supported on the channels made available are also potentially high. Also the cost per 25 

kHz channel decreases as the number of channels used for data increases (since the 

same equipment can be used to support a large number of channels). 

In order to encourage the adoption of more efficient VDL solutions, it may be necessary to 

offer incentives or disincentives for aircraft to equip noting that there is little inherent 

marginal cost differential between the airborne equipment. 

Recommendation 5.3: It is proposed that new VDL services will occupy the spectrum 

between 136 and 137 MHz (i.e. that spectrum newly assigned to aeronautical 

communications). However this spectrum is already in use for analogue services which 

will have to be found new frequencies below 136 MHz. One of the problems with the band 

136 to 137 MHz revolves around industrial, scientific and medical (ISM) heating 

machines. Such machines operate at frequencies around 13 and 27 MHz at very high 

powers for the purposes of drying (biscuits and paint commonly). Whilst these devices are 

not intended to radiate, the high powers involved mean that even small amounts of 

harmonic distortion can produce signals at higher frequencies that can cause interference 

to other services. Unfortunately the 10 th harmonic of the 13 MHz band and the 5 th 

harmonic of the 27 MHz band fall into the aeronautical communications band. This 

causes particular concerns for airborne receivers which have a very large radio line-ofsight. 

It was common practise, prior to the opening of 136 – 137 MHz for aeronautical 

communications that these devices, if found to be radiating excessively on harmonic 

frequencies, were re-tuned such that the harmonics fell above 136 MHz and hence 

outside the aeronautical bands. This now means, however, that there are a large number 

of interfering carriers present on frequencies between 136 and 137 MHz. It will take 

further work by the relevant national administrations to clear these bands further so that 

they are suitable for the introduction of digital services (to which they cause greater 

problems than for analogue services). A first stage in the movement to data is to use 

136MHz+ for initial data services – Ofcom should work with the CAA to ensure that this 

part of the spectrum is used efficiently and that sources of interference are removed as 

soon as is practical. 

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Recommendation 5.4: The decommissioning of VOR navaids will provide additional VHF 

spectrum for communications. It is important to take action to agree timescales 

internationally for decommissioning and to assist NATS in varying the terms of its licence 

if required to remove barriers to decommissioning. Assistance may be required to GA 

users if the VOR network is decommissioned. Ofcom should work with the CAA to 

encourage the decommissioning of VOR navaids and re-use of the spectrum for 

communication purposes. (Note that this is also discussed in Section 3.4). 

5.11.5 Long term measures 

Recommendation 5.5: It is important to determine a strategy for the long term transfer to 

data. This includes establishing plans for: 

• technology choice 

• clearing out of VHF spectrum 

Ofcom to work with CAA to ensure plans are put in place for a) the movement of voice to 

data and b) the gradual clearout and re-utilisation of the VHF spectrum 


For this illustration, it will be assumed that the movement of air traffic service voice to data 

involves an increase in spectrum efficiency which frees up most of the current VHF 

communication band, but requires wholescale introduction of a new technology. The 

costs will be approximated by the costs necessary to introduce VDL Mode 2 plus 

automation of control suites: 

• £81k, airborne costs 

• £51k per ground station 

• 11,000 aircraft 

• 150 ground stations 

• £450M for CWP upgrade 

• £160M for network 

The figures above are taken from the data link roadmap study carried out for the 

European Commission and apply to the European region. It will be assumed that 20% of 

these costs can be apportioned to the UK. 

It will also be assumed that most of 18MHz voice spectrum could be freed up. See Table 

5-16 below. 

Cost element 

ATC station upgrade + Network conversion £124m 

Non-ATC station upgrade N/A 

Aircraft station upgrade £178m 

Total cost £302m 

Annualised total £32.2m 


Cost per 25 kHz £45k 

Table 5- 16 Costs to introduce VDL Mode 2 plus automation of control suites 

Page 189

Discussion: Clearly the imposition of spectrum charging will be unwelcome to a 

community already struggling to profit from air traffic operations. However, there may be 

opportunities for commercial users to fund other users. For example, the use of spectrum 

for commercial and passenger data has huge potential and it is possible that the costs of 

employing more spectrally efficient solutions could be offset by making the freed up 

spectrum available to commercial uses. 

Note that any proposal to introduce spectrum trading will be difficult if aeronautical 

regulators are worried about safety of life issues. The adoption of new technology would 

need to be coordinated to free up usable spectrum. This suggests that the best solution 

might be to have a central body managing the upgrade and selling the spectrum. 

Individual licensees would have to entrust their “property rights” to the central body, which 

some may be unwilling to do. 

Recommendation 5.6: Ofcom, working with the CAA, should ensure that solutions 

considered for future data link technology are beneficial when viewed from spectrum 

utilisation and that no longer utilised spectrum is freed up where possible. There is 

consensus that aviation requires a new data link for future needs from 2012/2015+. The 

long term technology choice needs to consider: 

• the potential for low cost satellite based services, possibly shared with 

commercial uses 

• the potential for an optimised system utilising the VHF spectrum. 

The satellite route offers the possibility of sharing services with commercial users 

providing a possible route to lower cost. It seems preferable that aviation should avoid 

implementing a bespoke system. 

Use of a VHF system has the advantage of using spectrum dedicated solely to aviation 

use and providing a terrestrial system under the control of the aeronautical industry. The 

introduction of a new system will require a concerted effort to clear out existing use of the 

band. 

In all likelihood a dual strategy will be pursued with new systems operating both in the 

VHF and L bands. Ofcom needs to ensure that its own views on spectrum utilisation feed 

directly into the planning process in order that spectrum efficient solutions emerge. 

Recommendation 5.7: Ofcom should also investigate the possibility of applying in cooperation 

with the Ministry of Defence, the principles of recommendation 5.1 to the airground-air 

bands in the range 230 – 380 MHz, with a view to initiating a reduction in airground-air 

bands, ideally within NATO, Europe or as a minimum within the UK. 

Page 190

6 Maritime Communications 


The requirements of the maritime industry depend heavily upon the economic 

development and activity within this industrial sector. In recent years the sector has 

shown some slight economic and industrial growth. Profit margins have improved and 

financial investment in the sector is increasing. Developments and implementations of 

new technologies have generally been restricted to the minimum needed to comply with 

administrative and safety requirements. 

In the short term most companies are likely not to have ambitious plans for the 

implementation of new technologies for radiocommunications; however some small 

projects might be initiated which are aimed to improve efficiency in the movements of 

vessels, passengers, and freight. 

Most freight and passenger operators agree that in the long term there is the need for the 

further integration of maritime transport with inter-modal transport. This applies 

particularly to freight transport and requires that no intermediate handling of goods takes 

place at the modal switch, thereby reducing the total transportation time of cargo and 

reducing errors in handling at intermediate steps. 

Both in freight transport and in passenger transport, the trend towards the development of 

inter-modal, door-to-door, services is one of the most important issues. This development 

of inter-modal services, together with the enlargement of ships to gain economies of scale 

advantages are probably the most important developments envisaged for the maritime 

industry. Information is essential for the efficient planning and co-ordination of land 

transport with maritime transport. Delays will increase the turnaround times of vessels in 

ports, thereby decreasing the efficiency of the vessel and resulting in an increase in the 

cost of transportation. 

Efficient ship-shore communications and the availability of electronic navigational aids 

can facilitate efficient planning of port activities and could help ensure that ships are 

managed within designated time slots. 

Developments in the integration of land-based information (fleet owner, freight operator 

and fishing agency) with maritime/vessel-based information are required to achieve 

optimal operational efficiency. This will lead to the creation of “integrated ship 

management systems” and will improve efficiency of ship operations, which in turn will 

reduce turn-around times in ports and therefore reduce operational expenses of fleet 

owners. 

Maritime transport has always been important to the United Kingdom as an island nation. 

In general, the development of the transport industry depends heavily on the development 

of the economy as a whole. Transport demand, for both cargo and passengers, for all 

modes of transport has shown uninterrupted growth since 1970. 

Maritime transport, and in particular maritime cargo transport, experienced a growth of 

35% in the late 1970’s and the start of the 1980’s, but has diminished in absolute terms 

slightly in subsequent years. Maritime transport is very important for trade between 

Europe and America/Far East countries and for transport between the different European 

countries. 

Within the EU the European Commission has developed and is maintaining a Common 

Transport Policy, which has been implemented in order to ensure that the transport sector 

can take full advantage of the implementation of the Single Market. 

Page 191

This Chapter has addressed the spectrum management and socio economic issues 

involving a number of maritime radiocommunications systems located on land and on 

ships, with a few to ascertaining whether the spectrum involved could be used in a more 

efficient manner within the United Kingdom. At the end of this Chapter the Consultant has 

included a number of recommendations which the UK Office of Communications may 

wish to consider. 

The various sub-sections which follow, address a number of aspects of maritime 

radiocommunications systems. Where there are differences between land based and 

mobile application of the same technology or system, this is referenced in the text. 

Throughout the various sections in this Chapter reference is often made to a 3 character 

code designating the class of emission employed. The origin of the code is contained in 

Appendix 1 (Classification of Emissions and Necessary Bandwidths) to the ITU Radio 

Regulations. 

6.2 Short Range Devices 

There appears to be a growing requirement for the use of SRDs on board ship. In recent 

years, radio systems for short-range communications, remote control and monitoring 

purposes have been developed as well as wireless local area networks and Bluetooth 

applications. 

Particular operational applications that might be of interest on board a ship are: 

monitoring systems for engine parameters, door lock registration systems, wireless 

communications in enclosed spaces and the remote operation of davits. 

6.2.1 Frequency and socio-economic considerations 

The technical characteristics of the equipment, in particular the operating frequencies, 

should be such that systems may be used internationally. There are no special 

frequencies identified for such applications within the ITU Radio Regulations. However in 

principle any frequency allocated to the mobile service or the maritime mobile service 

might be used for such applications in international waters. 

The identification of harmonised frequencies for short range devices is becoming an ever 

increasing problem on a global scale. Essentially SRDs in most countries operated on a 

deregulated basis and many are inexpensive consumer products. And there is a 

fundamental issue that regional frequency allocations vary considerably between Europe 

and the Americas. Many SRDs find their way across the Atlantic in tourists’ suitcases and 

in both Europe and N America interference has occurred from such devices. Is this 

relevant to the maritime situation? To a certain extent it is, since frequency bands 

identified for SRD applications on ships in port and within territorial waters are likely to 

follow regional trends. 

The CEPT has adopted Recommendations T/R 70-03 to deal with low power and short 

range devices. There are a number of annexes dealing with very specific items such as 

the detection of avalanche victims or high performance wireless LAN, however Annex 1 

deals with non specific SRDs and this annex is reproduced below in Fig 6-1. The 

European Telecommunications Standards Institute (ETSI) has now developed 

harmonised standards (see section 4.4) and voluntary standards for the majority of these 

devices. Other standards or technical specifications might be applicable within the 

framework of the R&TTE Directive. The term “Short Range Device” (SRD) is intended to 

cover the radio transmitters which provide either unidirectional or bi-directional 

communications and have a low capability for causing interference to other radio 

equipment. SRDs use either integral, dedicated or external antennas and all modes of 

modulation can be permitted subject to relevant standards. Due to the many different 

services provided by these devices, no description can be exhaustive; however, the 

Page 192

following categories are amongst those covered, telecommand and telecontrol, telemetry, 

alarms and speech and video. 

For CEPT countries that have implemented the R&TTE Directive, Article 12 (CE-marking) 

and Article 7.2 on putting into service of radio equipment apply. The latter Article states 

that ”member states may restrict the putting into service of radio equipment only for 

reasons related to the effective and appropriate use of the radio spectrum, avoidance of 

harmful interference or matters relating to public health.” For Short Range Devices an 

individual licence is normally not required. 

But, for particular applications an individual licence may be required, for example where 

national frequency bands are chosen within broad tuning ranges. 

Let us take an example where Norway has adopted a ship-borne system for remote 

operation and registering of door locks, operating on 869.850 MHz. There are no specific 

technical standards for such systems, but the equipment should at least fulfil relevant 

EMC requirements, e.g. those specified in IEC standard 60945. Additionally, the radiated 

output power is required to be less than 5 mW. No protection is given to short range 

systems and these systems should not interfere with other radio systems on board. If 

Annex 1 of CEPT Recommendation T/R 70-03 is studied it can be seen that the 

frequency 869.850 MHz falls within sub-band k) allocated for 5mW systems in CEPT 

countries. To test whether the device is likely to be permitted in US ports, the band plan in 

the United States has been studied. The band 869 – 894 MHz is paired with 824 – 849 

MHz and is used for the Cellular Radiotelephone Service and is designated as the subband 

for mobile receivers. Thus base stations in the vicinity of the port may block the 

SRD and the SRD could cause interference to the cellular handsets of persons visiting 

the ship. Conversely in Europe, spectrum below 862 MHz is widely used for television 

broadcasting, which is why the band plans for broadcasting and mobile applications in the 

850/900 MHz area vary considerably between the two continents. 

One classification of frequency band, often used for low power devices might however be 

a candidate for global SRD devices and indeed some sub-bands are already being used 

for just such applications e.g. IEEE 802.11 and Bluetooth devices at 2450 MHz. Some of 

the frequencies allocated for Industrial, Scientific or Medical (ISM) applications are listed 

in the Radio Regulations and are available on a global basis. It is these frequencies that 

might be considered in the first instance for maritime SRD applications. Many of the 

bands are also included in Recommendation T/R 70-03. In particular the ISM bands 

centred on 13.56 MHz, 40.68 MHz, 2450 MHz, 5.8 GHz, 24.125 GHz and 26.953 - 27.287 

MHz may be candidates. It should be noted that the CEPT and ITU Region 1 ISM band at 

433.92 MHz and the ITU Region 2 ISM band at 915 MHz are not available on a global 

basis. 

If a solution based on globally available ISM bands does not meet all maritime 

requirements, the next best alternative would be to harmonise solutions capable of being 

implemented on a regional basis. In this regard it may be appropriate to specifically 

identify SRD bands appropriate for maritime applications in CEPT Recommendation T/R 

70-03. Such a course of action might be considered by the UK. 

Recommendation 6.1: If a frequency solution for Short Range Devices (SRDs) 

based on globally available ISM bands does not meet all maritime requirements, the next 

best alternative would be to harmonise solutions capable of being implemented on a 

regional basis. In this regard it may be appropriate to specifically identify SRD bands 

appropriate for maritime applications in CEPT Recommendation T/R 70-03. It is 

recommended that such a course of action might be considered by the UK in WG FM of 

CEPT ECC. 

Page 193

Figure 6-1 Reproduction of Annex 1 of CEPT ECC Rec. T/R 70-03 on SRDs 

6.3 LF DGPS 

6.3.1 Frequency Allocations (international) 

The band 283.5-315 kHz is allocated in Region 1 on a primary basis to the aeronautical 

radionavigation and maritime radionavigation (radiobeacons) services. In the European 

Maritime Area (EMA), this band was planned for the maritime radionavigation service 

(radiobeacons) at the Regional Administrative Conference for the Planning of the 

Maritime Radionavigation Service (Radiobeacons) in the EMA, Geneva, 1985. 

According to RR 5.73, in the band 285-325 kHz (283.5-315 kHz in Region 1), radio 

beacon stations in the maritime radionavigation service may transmit supplementary 

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navigational information using narrow-band techniques, on condition that the prime 

function of the beacon is not significantly degraded. 


DGPS or DGNSS provides differential corrections to GPS or other navigational satellite 

system receivers in order to improve navigation accuracy and, in addition, monitors the 

integrity of satellite transmissions. 

Integrity monitoring of the reference stations is a vital feature of DGPS. The stations test 

for GPS signals that are out of specification and immediately notify users to disregard the 

signal. With DGPS, this warning occurs within a few seconds of the satellite becoming 

‘unhealthy ’, compared to the GPS system, where up to 12 hours can elapse before 

notification is received. Such improved accuracies are required because the use of highly 

accurate positional information is central to the functioning of navigational aids like 

Electronic Chart Display and Information Systems (ECDIS) and Automatic (ship) 

Identification System (AIS). 

Each DGPS radio beacon comprises of two independent GPS receivers, (including 

special software to calculate the corrections), an MSK modulator, a transmitter operating 

in the LF/MF band (285 - 325 kHz), a DGPS station controller and an integrity monitor. 

Critical components of the system are redundant and the DGPS radiobeacons are 

remotely controlled and monitored 24 hours a day. 

This form of DGPS uses pseudo-range (distance measurement) corrections and rangerate 

corrections from a single reference station, which has sufficient channels (typically 

12) to track all satellites in view. Pseudo-ranges are simultaneously measured to all 

satellites in view, and using the known position of the receiver’s antenna and the 

positional data from each satellite, the errors in the pseudo-ranges are calculated. These 

errors are converted to corrections and are broadcast to user receivers. The user’s GPS 

receiver applies the corrections to the pseudo-ranges measured to each satellite used in 

its position calculation. The GPS receiver always applies the latest corrections received. 

Using this method, and depending on the user-to-reference station separation and the 

age of the corrections being applied, horizontal accuracy of the system can be improved 

from 13 to 22 metres (95%of the time) to better than 10 metres (95%of the time). 

Typically in operational stations accuracies of 2-4 metres can be expected from a typical 

maritime DGPS receiver. 

Technical, economic and administrative factors have indicated that the use of maritime 

radiobeacons is therefore a feasible solution for the transmission of differential 

corrections. The propagation of transmissions from maritime radiobeacons is mainly by 

ground wave with a usable range that does not exceed the range of applicability of the 

reference station corrections. The further the user is from the reference station, the less 

accurate the navigational solution is likely to be. Many administrations have therefore 

implemented facilities to provide such differential corrections. The technical 

characteristics of maritime beacons used for the transmission of the differential correction 

signal and for associated receivers are given in Recommendation ITU-R M. 823-2. 

Appendix 12 to the Radio Regulations contains, inter alia, field strength values on which 

the daylight service range of the radiobeacon station shall be based. 


There are no specific operational requirements. The system can work in a given area with 

one station transmitting the correction signals. However, in order to guarantee maximum 

use in a larger sea area that is covered by maritime radiobeacon stations from more than 

one administration; these administrations normally coordinate their efforts. In this regard 

IALA has issued guidelines on bilateral agreements and inter-agency Memorandums of 

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Understanding on the provision of DGNSS services in the frequency band 283.5 kHz – 

325 kHz. 

The objective of these Guidelines is to provide examples of Bilateral Agreements and an 

Inter-agency Memorandum of Understanding that set out the responsibilities of the 

countries and agencies concerned. They also indicate the procedures necessary to 

maintain the service at the required level of accuracy and availability for use in areas 

where stations located in two or more countries provide a DGNSS service. Such a 

situation exists between the United Kingdom and Ireland, see Figure 6-2 below. 

Figure 6-2 DGNSS stations in the United Kingdom and Ireland 

Radiobeacons transmitting differential correction signals are not part of the Global 

Maritime Distress and Safety System. 

6.3.4 Regulatory and Standardisation issues 

The technical characteristics of the system, including the data format of the correction 

signal, must be standardised according to Recommendation ITU-R M.823-2, otherwise 

the usability of the system would be at risk. However many countries ensure equipment 

has been designed to comply with the relevant prevailing standards of the RTCM and 

IALA. 

In particular the RTCM has developed two relevant documents which are used within the 

industry in the development of systems and equipment: 

• RTCM Recommended Standards for Differential GNSS (Global Navigation 

Satellite Systems) Service, Version 2.3 (RTCM Paper 136-2001/SC104-STD) – 

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This standard is used around the world for differential satellite navigation 

systems, both maritime and terrestrial. 

• RTCM Recommended Standards for Differential Navstar GPS Reference 

Stations and Integrity Monitors (RSIM), Version 1.1 (RTCM Paper 137- 

2001/SC104-STD) – A companion to the preceding standard, this standard 

addresses the performance requirements for the equipment which broadcasts 

DGNSS corrections. 

Furthermore IEC has developed the standard IEC 61108 addressing performance 

standards for maritime navigation and radiocommunication equipment and systems - 

Global navigation satellite systems (GNSS). 

The radio-beacon equipment and the ship-borne equipment (receiver for the differential 

correction signal) have to comply with the R&TTE Directive. 


The remaining error sources (clock, ephemeris, ionospheric and tropospheric) vary much 

more slowly than when the system operated under the Selective Availability (SA) mode 

prior to May 2000. Consequently the rate at which corrections must be received is now 

much lower. Depending on the characteristics of the DGNSS user receiver this could 

result in a marked improvement in the effective availability of the service in areas of 

marginal coverage, because loss of signal for periods of several minutes will have little or 

no effect on accuracy. Integrity may now be the primary factor determining required 

DGNSS update rate. 

The IALA Radionavigation Committee has identified four possible routes for development: 

1. Reduction of the data rate, providing better range because the energy would be 

concentrated in a narrower bandwidth. 

2. Reduction of the frequency of correction messages allowing the increased 

provision of other standard messages 

3. Addition of messages containing phase corrections giving sub-metre accuracy. 

4. Addition of messages containing meteorological or hydrographic data. 

Another concept that could be considered is the broadcasting of ionospheric corrections 

derived from a wide-area model, rather than the values obtained at the broadcast site 

alone. This could lead to an integrated network of stations rather than stand alone 

broadcast sites, but it does introduce much greater reliance on communication links. 

A future version is likely to include improved datalink integrity using cyclic redundancy 

checks and a more efficient message structure. It is likely that the new format will be 

introduced on different frequencies in particular application areas, requiring centimetre 

accuracy for specialised applications such as docking. The provision of additional 

frequencies for these stations might not present much of a problem in the Americas, 

Africa or Asia, where channel spacing can be reduced from 1 kHz to 500 Hz, but in 

Europe, where spacing is already 500 Hz and the band is fully utilised, it would be 

necessary to plan such a change in conjunction with the withdrawal of the remaining 

direction-finding beacons. 

Recommendation ITU-R M.1178 indicates that in order to permit more efficient use of the 

maritime radio navigation band, regulatory arrangements should be made to allow for the 

transmission of maritime navigational information using narrow-band techniques from 

stations other than radiobeacons. However, the Recommendation does not indicate any 

alternative station or frequency band. 

Page 197


Apart from the system enhancements mentioned above no new technologies are 

anticipated in this band for maritime applications. 


It is quite possible that the European navigation satellite system GALILEO will provide an 

accuracy that does not require any auxiliary system for the enhancement of the basic 

accuracy of the navigational satellite system. An announcement by the United Kingdom 

was made to the 44th session of the IMO’s Sub-Committee on Safety of navigation 

that it intended to discontinue the radiobeacon service operated by the three General 

Lighthouse Authorities (Trinity House, Northern Lighthouse Board and 

Commissioners of Irish Lights) on 1 February 1999 in accordance with the Marine 

Navigation Plan (MNP). The MNP provided for discontinuation of this service by the 

year 2000 or sooner. The advent of GALILEO together with the closure of 

conventional maritime beacons would make the transmission of supplementary 

navigational information from radiobeacon stations superfluous. 

Should GALILEO and its predecessor EGNOS materialise as planned (see 6.3.9.4) the 

spectrum used for DGPS/DGNSS could be considered for alternative applications such 

as broadcasting. 

6.3.8 Allocation Sharing issues 

The band 283.5-315 kHz (Region 1) is shared with the aeronautical radionavigation 

service on a co-primary basis. Due to the establishment of the radiobeacon plan in the 

European Maritime Area including the modification procedures, no sharing problems have 

arisen. 

In Region 1, the frequency band 285.3-285.7 kHz is also allocated to the maritime 

radionavigation service (other than radiobeacons) on a primary basis (Radio Regulation 

(RR) No. 5.74). This band is used for a hyperbolic maritime radionavigation system in 

accordance with Recommendation ITU-R M. 631. No sharing difficulties with maritime 

radiobeacon stations have been reported. 


Conventional maritime radio-beacons provide a backup to more sophisticated 

radionavigation systems and are the primary low-cost, medium accuracy systems for 

ships equipped with only minimal radionavigation equipment. The beacons are used for 

direction finding. The number of such beacons has been steadily declining in recent 

years, which has provided the opportunity to implement DGPS beacons on a global basis, 

thus maintaining a reasonable level of spectrum efficiency as well as the development of 

a cost effective accurate navigational aid. 

The present differential correction system can thus be considered to be spectrally 

efficient, since it is supplementing maritime radiobeacons used for DF applications 

without adversely affecting that prime function. No improvements are therefore required. 

6.3.9.1 System Issues 

The Global Positioning System (GPS) is a United States Department of Defense 

developed, worldwide, satellite based radionavigation system operating in the 1215 -1240 

MHz and 1559 -1610 MHz bands. It was inaugurated in 1994. Although a principal part of 

the Global Navigation Satellite System (GNSS) its strategic importance in times of crisis 

has always been of concern to civilian users (especially non US users) who worry that 

service could be withdrawn. On the other hand the use of GPS is presently free of charge. 

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No change in this approach is envisaged. It is, however, quite likely that GALILEO, which 

will be mainly operated on a commercial basis, will levy fees for its use. 

6.3.9.2 System Longevity 

Some users and manufacturers have questioned the continuing requirement for DGNSS 

with the ending of SA, post May 2000. Much of the investment in the UK and Ireland has 

already taken place, but in spectrum terms it is appropriate to review the need for 

DGNSS. 

The continuing need for DGNSS is very much application dependent. Although GPS 

without SA provides an accuracy of approximately 15-25 m (95%), there remains an IMO 

requirement for 10 m accuracy in the harbour entrance and approach phase of 

navigation, which can only currently be met by DGNSS. Leisure craft were well-served by 

the 60-100 m (95%) accuracy of raw GPS; the removal of SA has improved that accuracy 

even further, although not to the extent afforded by DGNSS. Aside from accuracy, the 

other main benefit of DGNSS is the enhanced integrity of the navigation solution. 

Commercial vessels negotiating restricted channels could easily justify DGNSS on 

grounds of integrity monitoring alone. Specialised positioning applications such as 

dredging and hydrographic survey and in particular buoy positioning by the lighthouse 

authorities themselves will continue to benefit from the improved accuracy and integrity 

afforded by DGNSS, whereas much of the fishing industry probably needs no 

improvement on GPS without SA. The emerging reliance on automatic positioning 

systems using ECDIS, automatic pilots and AIS also impose greater requirements on 

positioning accuracy and integrity. 

It is anticipated that DGNSS will remain a core navigation service for maritime safety and 

efficiency for about the next 10 years. 

6.3.9.3 International Agreement 

The General Lighthouse Authorities’ or GLA’s (Trinity House, Northern Lighthouse 

Board and Commissioners of Irish Lights) DGPS facility is an integrated British Isles 

system and is the newest element of the mix of visual, audible and electronic aids to 

navigation provided by the three GLAs of the UK and Ireland under their MNP. 

The MNP resulted from widespread consultation with the maritime community on the 

requirement for Marine Aids to Navigation into the 21st century. The plan was devised to 

ensure the ongoing provision of a satisfactory, economical and reliable ‘aids to navigation 

service’ to meet the changing requirements of all classes of mariner. 

DGPS, which became operational on 1 July 2002, is a network of 14 ground-based 

reference stations providing transmissions with coverage of at least 50 nautical miles 

around the coasts of the United Kingdom and Ireland. It is an open system - available to 

all mariners - and is financed from light dues charged on commercial shipping and other 

income paid into the General Lighthouse Fund. 

Dependent on the conditions of the UK and Irish MNP, the UK may not have too much 

scope for spectrum changes whilst the DGNSS is seen as a key element of the ‘aids to 

navigation’. 

Furthermore, whilst DGNSS is not subject to mandatory IMO carriage requirements it is 

clear that DGNSS services have been implemented around the globe and provide an 

important service for maritime safety. 

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6.3.9.4 Possible Replacement System 

In determining whether spectrum can be released and can be considered a candidate for 

refarming, one must first examine whether an alternative is available and if possible the 

cost implications of such a move. 

The European Space Agency’s Galileo project (GNSS-2) aims to launch a group of 

satellites to provide the EU with an advanced positioning and navigation system under 

civilian control. The system should be operational in 2008. Galileo’s predecessor, the 

EGNOS project (GNSS-1), will boost the performance of existing GPS and Glonass 

systems. Geostationary satellites will augment GPS and Glonass signals by sending 

corrections to EGNOS receivers. EGNOS is part of EUROCONTROL’s Satellite Based 

Augmentation System project. Measurements made during EGNOS trials have shown 

that accuracies of 3.8 m were achieved in 95 percent of cases and within 1.35 m in 50 

percent of the cases. This is a considerable improvement in accuracy, compared to GPS 

and is of a similar order to current DGPS results. 

The rationale for developing Galileo is: 

• Strategic, in order to protect European economies from dependency on other 

states’ systems, which could deny access to civil users at any time, and to 

enhance safety and reliability. The only services currently available are the US 

Global Positioning Service (GPS) and the equivalent Russian system, both 

military but made available to civil users. 

• Commercial, although Galileo will not be able to charge for the use of its basic 

service, because it is accepted that users need to have free open access, it 

could become a commercially viable business by providing value added services 

which will establish a position in the market alongside GPS. 

• Economic, to secure an increased share for Europe in the equipment market and 

related technologies, deliver efficiency savings for industry, create social benefits 

through cheaper transport, reduced congestion and less pollution and stimulate 

employment. 

The services likely to be offered are: 

• A free Open Access Service providing basic positioning navigation and timing 

signals as a new universal service; 

• Chargeable Commercial Services based on additional encrypted data; 

• Safety of Life Services which will provide greater accuracy and integrity, allowing 

the user to know within a few seconds if the positioning information has become 

corrupted; 

• A Search and Rescue Service which identifies a user’s location to civilian 

emergency services; 

• A Public Regulated Service based on a robust signal, resistant to interference or 

jamming and restricted to certain public security organisations such as police 

and fire services. 

On current knowledge it would seem that prior to the projected lifetime of current 

generation DGPS/DGNSS systems Galileo may be on track to provide a comparable 

service to DGPS for safety of life applications. This of course assumes that European 

thinking will maintain a viewpoint that safety of life services should be funded from tax 

receipts or should be subsidised by commercial services. In terms of cost to Ireland and 

the UK there is likely to be an eventual cost saving as DGPS stations are 

decommissioned and their call on the General Lighthouse Fund is minimised. 

Page 200

However the situation would be somewhat different for users. It is likely that a new 

receiver would have to be fitted for Galileo systems; indeed one scenario suggests that 

the Galileo Operating Company will obtain revenue from royalties on chipset sales, paid 

by equipment providers who incorporate a Galileo chip in their products, to allow users to 

get the open access service. Additional revenues would come from service providers who 

envisage utilising the encrypted signals to offer other enhanced services. With such 

scenarios in mind it is likely that a significant period of time must elapse before the current 

DGPS can be curtailed since the navigation of UK and Irish waters by non British Isles 

(Ireland, UK and Isle of Man) flagged vessels could be impaired. The current cost for 

DGPS equipment is between £600 and £2000. On top of this would be the cost of fitting 

and training. This cost in turn may be extrapolated to provide a hint of the possible costs 

involved if a country’s maritime fleet required to be fitted with new equipment. 

Until such time it is also clear that the accuracy advantage afforded by DGNSS (1-10 m) 

remains essential for meeting the IMO requirement for navigation in restricted waters. In 

addition the accuracy advantage of DGNSS remains significant for specialised positioning 

applications, whilst the relaxed requirement for data latency may improve the effective 

availability of the service in marginal areas and offers the potential to reuse part of the 

datalink capacity. This opens up many opportunities to improve the service by increasing 

coverage or by providing additional information. Lastly, the introduction of phase 

corrections could allow the service to meet the most stringent accuracy requirements in 

IMO Resolution A.860(20). 

6.3.9.5 Possible use of eventual vacated spectrum 

The band 283.5 - 325 kHz is adjacent to the 148.5 – 283.5 kHz LF broadcasting band in 

Region 1 and overlaps and is adjacent to the primary and exclusive aeronautical 

radionavigation band 325 – 405 kHz used for non directional beacons (NDBs). 

It would seem that the DGPS could to a certain extent be treated in a similar manner to 

any overall review of spectrum between 283.5 kHz and 526.5 kHz which might occur as a 

result of the availability of Galileo services in Europe towards the end of the decade. This 

could open the door to a sound broadcasting band extending from 148.5 kHz to 1606.5 

kHz. There would appear to be a limited number of other radiocommunications 

applications that might make use of this LF and MF spectrum which might be refarmed. 

If then the band 283.5 – 325 kHz is considered as a possible candidate for broadcasting; 

conventional LF broadcasting systems are ideal for wide area coverage but require high 

power transmitters and very large antenna arrays. It would also be advisable to seek 

CEPT agreement on any plans to change the service designation in the band, in view of 

the large co-ordination distances involved for broadcasting and the situation that the 

current service designation in the frequency band is to a safety service. 

The last two LF broadcasting services launched in the British Isles were established on a 

commercial basis in Ireland to predominantly serve a UK market. The music station 

Atlantic 252 was launched in 1989 and closed down in December 2001. The Irish public 

service broadcaster RTE held 20 per cent of the shares. Bids of up to £60 million were 

expected when Atlantic 252 first came on the market in early 1998. In 2001 CLT (Radio 

Luxembourg) disposed of their 80 per cent share for £2 million after the parent company 

sold the station to the sports station, Teamtalk. Teamtalk 252, a live sports station 

launched in March 2002 itself closed in July 2002. The holding company disposed of its 

80% shareholding to RTE. The experience is therefore that the economic viability of large 

AM LF commercial stations is at least questionable, in view of numerous competing local 

services, poor music quality and the limited availability of advertising revenues for 

nationwide radio services. 

However potential operators of DRM (Digital Radio Mondiale - a universal, nonproprietary 

digital AM radio system with near-FM quality) many of which are public service 

Page 201

oadcasters could be interested in the possibility of a new European wide-area band in 

which DRM could be launched without impacting established LF stations. Although the 

DRM signal is designed to fit in with the existing AM broadcast band plan, based on 

signals of 9 kHz or 10 kHz bandwidth with modes requiring as little as 4.5 kHz or 5 kHz 

bandwidth, DRM can take advantage of wider bandwidths, such as 18 or 20kHz which 

could exploit a new band. Besides providing near-FM quality audio, the DRM system has 

the capacity to integrate data and text. The benefits of Digital AM for receiver, transmitter 

and semiconductor manufacturers are: 

• Bringing longevity to older AM technologies; 

• Opportunity to identify possibilities for new areas of interest; 

• Increasing the market potential for transmitting and receiver systems; 

• Optimising return on investment for dual technology components for low data 

rate systems applied to narrow-band transmission channels; 

• Opportunity to effectively influence cost-effective design concepts for future AM 

radio systems; 

• Through DRM, active participation in AM digital development. 

In addition global harmonisation of the DRM standard has the potential possibility of 

providing an estimated market of 2.5 billion DRM receivers world-wide. Of course the 

benefits of such a harmonised global market would be diminished somewhat if national or 

regional solutions were to be adopted, nevertheless there would be sufficient component 

commonality to achieve significant economies of scale. 

In January 2003, the International Electrotechnical Committee (IEC) voted in favour of the 

DRM standard IEC 62272-1 Ed. 1: Digital Radio Mondiale (DRM) - Part 1: System 

Specification. 

There could also be an argument for leaving MF and LF spectrum fallow as it becomes 

available for reallocation. EMC issues and a gradual increase in the noise floor can make 

the reception of LF and MF broadcasting services particularly difficult. Further, broadband 

wire-line electronic communications networks will increasingly use MF and LF frequencies 

in the domestic environment. Many studies have hinted that radiocommunications 

services and non-intentional wire-line radiators may be difficult sharing partners. Until 

more efficient broadband delivery mechanisms have been developed it may be preferable 

in the interests of broadband deployment and increased local loop competition to limit 

further radio expansion and the launch of new radiocommunications services in affected 

frequency bands. 

6.3.9.6 Conclusions 

Any changes in the DGPS band could not be envisaged until the end of the decade when 

more accurate GNSS systems become available. Any policy decisions need to be taken 

with the knowledge that DGPS deployment in the British Isles involves two sovereign 

jurisdictions. There would seem to be little negative impact on the General Lighthouse 

Authorities as it is unlikely that a differential element will be required for the next 

generation of GNSS systems. 

It is also possible that users will not be affected as general navigation, safety of life and 

search and rescue activities may be provided without imposing direct charges. 

If the band likely to be vacated is considered for broadcasting it would be preferable to 

seek agreement in CEPT in view of the likely large co-ordination distances involved. It is 

difficult to quantify the value of a new LF broadcasting band to broadcasters in view of the 

commercial viability of such stations. However a band in which to launch DRM could be of 

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interest to broadcasters and manufacturers alike but a UK and possibly Irish only solution 

would probably not provide a sufficient market base to proceed with such a project. 

There is also an argument for reducing MF and LF radiocommunications utilisation in the 

near term in view of likely EMC problems with unintentional RF radiators, including wireline 

electronic communications networks in the conurbations. Once optical fibre or fixed 

wireless access to the home has become widely deployed such a policy, if adopted could 

be reviewed. 

Recommendation 6.2: Section 6.3 and sections 6.5, 6.6 and 6.7 below have 

indicated a possibility for new technology or change of use within the foreseeable future. 

However either option would benefit from a European market and harmonised frequency 

bands to ease co-ordination difficulties and provide economies of scale for industry. It is 

therefore recommended that the UK lobby for a CEPT DSI process for the band 30 kHz to 

30 MHz within the CEPT ECC and the European Commission’s Radio Policy Committee, 

as well as introducing relevant technical, operational, economic and regulatory issues 

contained in this Report into the committee structure and decision making processes of 

the relevant international bodies. The overall objective should be to continue to promote 

innovation in the spectrum management process at the international level. 

6.4 GMDSS in the United Kingdom 

Before addressing maritime communications with respect to the services and 

technologies found in specific bands, it is necessary to address the Global Maritime 

Distress and Safety System (GMDSS) from a UK perspective. The GMDSS was first 

introduced into the IMO’s SOLAS Convention in 1988; it is addressed in several places 

throughout this Chapter because the regulatory and standardisation regime including 

carriage requirements for SOLAS vessels is somewhat different to those which are 

applicable to non SOLAS ships. 

IMO’s recommended GMDSS configuration uses a combination of digital selective (DSC) 

calling which uses telegraphy for automatic reception based on frequency shift keying. A 

DSC transmission provides key details of the vessel in an emergency situation, its 

geographical coordinates (entered manually or via a GPS interface) and the nature of the 

difficulty. The system then switches to a voice channel for a further exchange of 

information. Within the GMDSS, frequency pairs are used (see table 6-2 below), with one 

frequency designated for DSC and the other for radiotelephony. MF and HF DSC use 

radio Telex type signals (F1B) with a data rate of 100 Baud. 

In the UK there are only VHF and MF DSC coast stations, for sea areas A1 and A2 

respectively, the station locations and the range of coverage provided by these stations is 

shown below. There are nine MF equipped coast stations, namely: Aberdeen, Clyde, 

Falmouth, Holyhead, Humber, Milford Haven, Shetland, Stornoway and Tyne Tees. Sea 

area A1 extends 30-50 nautical miles from the coast and sea area A2 extends to 150 - 

250 nautical miles but excludes A1 designated areas. See table 6-1 and figure 6-3 below. 

Area 

Description 

A1 - within range of 

shore-based VHF 

stations 

A2 - within range of 

shore-based MF 

stations 

A3 - within 

Inmarsat satellite 

range 

Distance 40 - 90 km About 90 - 750 km 70º N to 70º S 

latitude 

Radio VHF MF 

VHF 

HF or Inmarsat 

MF 

VHF 

A4 - other areas (i.e. 

beyond Inmarsat 

range) 

North of 70º N or S of 

70º S 

HF 

MF 

VHF 

Table 6-1 Description of Sea Areas and radio link characteristics 

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The nearest receiving station for HF DSC is at Lyngby, Denmark, which monitors all the 

HF GMDSS frequencies for sea areas A3 and A4. 

Band Radiotelephony DSC 

MF 2182kHz H3E 2187.5kHz 

HF 4125 kHz J3E 4207.5kHz 

HF 6215kHz J3E 6312kHz 

HF 8219kHz J3E 8414.5kHz 

HF 12290kHz J3E 12577kHz 

HF 16420kHz J3E 16804.5kHz 

Table 6-2: GMDSS frequency pairs 

Figure 6-3 British Isles and North West Europe DSC limits of sea areas. 

Reproduced from Admiralty List of Radio Signals Volume 5 2001/02 by permission of the 

Controller of Her Majesty’s Stationery Office and the UK Hydrographic Office (www.ukho.gov.uk) 

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6.4.1 UK Search and Rescue (SAR) at HF and MF 

In addition to GMDSS, SAR requirements extend across all frequency bands. Most 

search and rescue radio traffic is confined to VHF; however 2596 kHz is assigned for 

SAR operations involving HM Coastguard (MCA) and the Royal National Lifeboat 

Institution (RNLI). 8364 kHz is assigned for SAR operations but is used only when the 

operational area is well away from land and for communications between aeronautical 

and maritime mobile stations. 

For on-scene communications during coordinated search and rescue operations, 2182 

kHz is used for distress and safety communications, 3023 kHz and 5680 KHz for ship to 

aircraft communications and 4125 kHz for ship to ship and ship to shore communications. 

Other UK SAR frequencies are shown in Table 6-3. 

Frequency Application 

3085 kHz SAR operations secondary 

3095 kHz Milford / Liverpool RAF SAR (Night) 

4710 kHz Liverpool RAF SAR (RAF Valley) 

5695 kHz SAR operations secondary 

5699 kHz SAR operations secondary (night) 

5860 kHz SAR operations 

11243 kHz Liverpool RAF SAR secondary 

Table 6-3 Additional UK SAR frequencies 

6.5 MF and HF Communications Services, Techniques and 

Technologies 

6.5.1 Automation and Adaptive Techniques 


In recent decades MF (above 1.6 MHz) and HF voice communications, originally AM 

double sideband and latterly SSB have been used for medium and long-distance 

communications. Such systems have a number of positive characteristics that can be 

enhanced as well as drawbacks that can be minimised through the use of automatic and 

adaptive techniques. The positive attributes for communication in MF and HF bands 

above 1.6 MHz include the ability to establish cost effective medium and long-distance 

transmission paths. The negative aspects include variable propagation, much lower 

overall reliability and limited data bandwidth. Communicating in these frequency bands 

requires the optimisation of conditions to make it reasonably reliable which is dependent 

on a large number of factors such as operator experience, operating frequency, the 

degree of ionisation of the ionosphere and the distance between stations (number of 

hops), 

In manual operation, a procedure used until recent years to optimise radio communication 

between points required the operator to adjust the parameters of the system for maximum 

performance as a result of the condition of the ionosphere and other propagation 

conditions. Present-day, automation techniques reduce the burden on the operator by 

adding subsystems for frequency management, link establishment, link maintenance, etc. 

Automation can be added to provide an impression of an MF/HF conventional 

Page 205

communications system when in reality the radio is a multi-channel communication device 

performing many underlying functions. 

In addition to these automation techniques, adaptive techniques can also reduce the 

burden on the operator while making the radio more responsive to changing HF radio 

propagation conditions. Adaptivity is the automatic process for modifying the operating 

parameters and/or system configuration in response to changes in the time-varying 

channel propagation conditions and external noise. 

At the transmission level, adaptive characteristics might include: data rate, waveform, 

error coding, power, and antenna type and pattern procedures as well as performance 

assessment characteristics unique to the transmission level. At the link level, adaptive 

characteristics include frequency management, ionospheric sounding, channel probing, 

and occupancy/congestion monitoring in addition to performance-assessment details. At 

the network level, adaptive characteristics include adaptive routing, flow control, protocol 

management, data exchange, and network reconfiguration, as well as performanceassessment 

details. At the system level, adaptive characteristics include system 

management, system-level frequency management and control, in addition to 

performance assessment details. 

6.5.1.2 Frequency Management 

There are generally considered to be three essential component parts in HF frequency 

management, long-term issues or propagation forecasts, short-term issues such as 

adjustments needed to compensate for an unpredicted change and current conditions. 

Adaptive frequency management deals with the issues that might be used to adjust 

frequency use, based on network conditions. At the link-adaptive level, the primary 

consideration is with the current conditions and the choice of frequency to use for a 

particular message. 

6.5.1.3 Real-Time Channel Evaluation (RTCE) 

The key to achieving significant benefits in the way that an automated HF radio system 

controller uses the HF propagation medium for communication is to ensure that an 

adequate supply of real-time data is available for decision-making purposes. The 

transceiver must keep track of propagating frequencies/channels based on the results of 

an analysis of real-time-channel-evaluation (RTCE) information to determine the best 

choice for message transmission. RTCE is the process of measuring appropriate 

parameters from a set of communication channels in real time and using the data thus 

obtained to describe quantitatively the states of those channels and hence the capabilities 

for passing a given class, or classes, of communication traffic. Once the details of those 

channels providing the required path have been determined, a channel ranking can be 

performed by taking into account the effects of path loss, noise, interference, multi-path, 

fading, dispersion, Doppler shift and specific user requirements. 

6.5.1.4 Users’ requirements 

Maritime MF and HF radio can be a cost effective alternative to satellite communication 

systems. Radio systems at these frequencies require a frequency channel that is as clear 

as possible (free of noise and interference). The attributes of the automated and adaptive 

radio communication link are such that it will regularly monitor the operation of the varying 

HF medium to exploit the spectrum with the greatest efficiency possible. Users’ basic 

requirements might be said to be the ability to key communicate automatically with other 

users on some common frequencies and networks without human intervention. 

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As MF and HF automatic link establishment radios evolve, their design is constantly being 

updated with new features and functions that increase the level of automation and 

increase the radio’s ability to adapt to changing propagation conditions. A fully adaptive 

MF/HF system typically operates under microprocessor control, incorporates automation 

for most functions, and is capable of a variety of diversity schemes with a set of channel 

intelligence functions for automatically establishing and maintaining links in an adaptive 

manner in response to time-varying channel propagation, external noise, and 

electromagnetic-compatibility (EMC) conditions. 

6.5.2 E-mail and Data Services 


Telex over Radio (TOR), generally referred to as Narrow Band Direct Printing (NBDP) due 

to its use of relatively narrow bandwidth in the HF spectrum (channels are spaced 500 Hz 

apart) and its direct printing capability has been an important element in maritime 

communications for many years. It was widely used up to the introduction of the GMDSS 

in 1992. Before the introduction of telex services utilising the Inmarsat space segment, 

initially through Inmarsat A and latterly via Inmarsat-C, TOR was the primary method of 

telex communications for ships at sea. ITU standards were developed and remain in force 

today. 

Inmarsat based systems gradually replaced NBDP because they were faster and more 

efficient, required less operator skills and were available continuously. 

A number of systems have been or are being developed. Norway has been testing an HF 

system capable of data communications including e-mail. Such a system might provide 

public correspondence and part of the GMDSS in sea areas A3 and A4. Because of the 

promising results distress communications may also be considered. 

6.5.2.2 GMDSS issues 

Subsequent to GMDSS implementation NBDP has been in rapid decline principally 

because most GMDSS installations include an Inmarsat-C capability that offers a user 

friendly always available telex option. NBDP uses low data rates by today’s standards (50 

Baud) and relied on operator intervention, an expensive commodity in an era when Radio 

Officers were gradually being phased out for routine communications and shore based 

telex systems were also in decline and closing around the world. Furthermore the modern 

electronic data communications world was already arriving on board ship with PCs and 

networking. 

Although NBDP was gradually disappearing, new methods of text communications based 

on terrestrial radio (HF) were being developed and growing in popularity. Norway 

proposed within the IMO that the mandatory requirements for MF/HF radio equipment to 

be fitted with NBDP for ships operating in sea areas A3 and A4 should be reconsidered, 

as the system was outdated. At that time COMSAR within IMO determined that NBDP 

should be retained until a viable alternative was found that would perform all the present 

functions of the NBDP. It was generally accepted that new mobile-satellite and MF/HF email 

systems were currently used at sea and could be considered as an alternative at a 

later stage, but this would need to be approved and adopted by the IMO for use within the 

GMDSS. 

Norway has again raised the issue at the IMO with the objective of considering HF E-mail 

as an alternative system to HF NBDP and the need to develop to develop performance 

standards accordingly. In addition at WRC-03 the ITU modified Appendix 17 of the Radio 

Regulations to permit maritime HF frequencies to be used for data transmissions. 

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6.5.2.3 Globe Wireless e-mail HF communication system 

In addition to the Norwegian trials a large commercial global HF communications network 

has been implemented by Globe communications. The Globe e-mail HF communication 

system has been in operation for about 9 years and uses a network of 23 sites in different 

countries around the world. Communications are fully automated and no radio operator 

skills are required. Software clients similar to those used with Internet email are employed 

and more than 4,000 ships, including those of all the major flags, use the system. 

It would appear that the capability, availability and reliability of this system may make it an 

ideal terrestrial wireless option for safety and reporting requirements such as those 

demanded by IMO mandated requirements of security alerting and long-range AIS. 

The system is much cheaper to operate than a satellite system while at the same time 

offering similar capabilities. GlobeEmail is an automated system, both from shore to ship 

and in the reverse direction. Every ship participating in the system is provided with 

customised software and a dual mode modem. The user on the ship uses the simple email 

client to send and receive messages, in a similar manner to POP3 E-mail. Another 

part of the software controls the HF radio. It scans the radio, sampling every channel 

used and identifies the six best frequencies, at any point in time. It also monitors the ‘outbox’ 

of the E-mail program and when a message is placed there, it automatically links 

with one of Globe’s shore stations and transmits the message. Sophisticated, errorcorrecting, 

transmission protocols have increased the reliability significantly and a 

network of stations around the world, linked to a central control point, provides coverage 

world-wide, including the polar-regions. This system and others like it were designed to 

overcome the deficiencies of past marine communications systems and any file, text, 

graphic or binary can be sent via radio. It is claimed that speed, reliability, and coverage 

is better than Inmarsat Standard C satellite performance. 

The combination of Digital Signal Processing and adaptive techniques produces the 

lowest available underlying marine communications costs. This is because a terrestrial 

system does not have to contribute to expensive space segment costs and does not have 

to invest in uplink earth stations. 

Standard HF radios and inexpensive computers can provide the enhanced adaptive 

techniques required for this service. 

Other developments have included technology that allows HF radio to transmit binary 

files. Previously radio NBDP and SITOR was the most sophisticated protocol available to 

ships. Telex has a very limited character set and is unable to transmit files such as word 

processing documents, spreadsheets, or interact with on line services. A new technology, 

named CLOVER, brings all of these features to HF radio. This new technology also 

dramatically improves the throughput available on HF radio. Telex operates at 50 Baud 

(bits per second). The GlobeEmail, using CLOVER moves data at a rate of 2400 bits per 

second. 

CLOVER is robust even under the poorest propagation conditions due to its use of a very 

low base data rate that relies upon differential modulation between pulses. The CLOVER 

signal fits perfectly within existing channel allocations because it consists of a time 

sequence of amplitude-shaped pulses. Its data throughput is always the highest possible 

since the CLOVER modem is capable of shifting among ten different modulation modes 

using various combinations of frequency, phase-shift and amplitude modulation. 

Some of the more important spectrum related and operational requirements of the system 

are: 

• The system should have the ability to simultaneously transmit and receive on a 

single channel pair of frequencies. 

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• The class of emission, in accordance with current ITU designators, is F7B. 

However, any emission type may be used provided the bandwidth does not 

exceed that allocated to the frequency in use. 

• Any bandwidth may be used provided that the bandwidth allocated to the 

frequency in use is not exceeded. 

• Since WRC-2003 many frequencies in the exclusive maritime mobile bands 

designated in Appendix 17 to the ITU Radio Regulations may be assigned. 

These include duplex voice channels, facsimile/data frequencies and frequencies 

previously assigned for Morse telegraphy. Frequencies in bands allocated to the 

maritime mobile or mobile services could also be used. 

• The radio used for this service should: 

1. utilise Digital Signal Processing (DSP) techniques; 

2. be capable of being controlled from a computer; 

3. have a pass-band with no group delay distortion and a pass-band 

ripple with a maximum variation of 0.5 dB; 

4. be frequency stable to +/- 10 Hz; 

5. be able to have its frequency accuracy, power and VSWR monitored 

remotely via a computer, 

6.5.3 NVIS (Near Vertical Incidence Sky-wave) Propagation Techniques 

NVIS, or Near Vertical Incidence Sky-wave, refers to a radio propagation mode which 

involves the use of antennas with a very high radiation angle, approaching or reaching 90 

degrees, along with selection of an appropriate frequency below the critical frequency, to 

establish reliable communications over a radius of around 300 km. Deliberate exploitation 

of NVIS is best achieved using antenna installations which achieve some balance 

between minimizing ground-wave (low angle of launch) radiation, and maximizing near 

vertical incidence sky-wave (very high launch angle) radiation. Successful NVIS 

communications depends on being able to select a frequency which will be reflected from 

the ionosphere even when the angle of radiation is nearly vertical. These frequencies are 

usually in the range of 2-10 MHz, though sometimes the limit is higher. A frequency is 

selected which is below the current critical frequency (the highest frequency which the F 

layer will reflect at a maximum 90 degree angle of incidence) but not so far below the 

critical frequency that the D and/or E layers have an adverse impact. 

NVIS techniques concentrate on the areas which are often in the skip zone. The skip 

zone is the region consisting of areas of the earth's surface which are outside the 

coverage area of the transmitting station's ground-wave but not sufficiently distant far to 

receive sky-wave reflections. The goal is to radiate a signal at a frequency which is below 

the critical frequency, at a nearly vertical angle, and have that signal reflected from the 

ionosphere at a very high angle of incidence, returning to the earth at a relatively nearby 

location. Absorption by the D layer, and other factors, determine some minimum 

frequency below which the signal will no longer be usable, and usually some distance 

beyond which signals will no longer be usable. 

One of the most effective antennas for NVIS is a dipole positioned from 0.1 to 0.25 

wavelengths (or lower) above ground where vertical and nearly vertical radiation reaches 

a maximum, at the expense of lower angle radiation. A dipole can be used at even lower 

heights, resulting in some loss of vertical gain. 

The advantages of NVIS operation include: 

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• Coverage of an area by NVIS techniques, which is normally in the skip zone i.e. 

that area which is normally too far away to receive ground-wave signals, but not 

yet far enough away to receive sky-waves reflected from the ionosphere. 

• NVIS requires no infrastructure such as repeaters or satellites. Two stations 

employing NVIS techniques can establish reliable communications without the 

support of any third party. 

• Signals propagated via the NVIS mode are relatively free from fading. 

• Antennas optimised for NVIS can usually be erected near to the ground. Simple 

dipoles work very well. 

• The path to and from the ionosphere is short and direct, resulting in lower path 

losses due to factors such as absorption by the D layer. 

• NVIS techniques can dramatically reduce noise and interference, resulting in an 

improved signal/noise ratio. 

• With its improved signal/noise ratio and low path loss, NVIS works well with low 

power thus facilitating spectrum sharing. 

The disadvantages of NVIS operation include: 

• Due to differences between daytime and night-time propagation, a minimum of 

two different frequencies must be used to ensure semi-reliable around-the-clock 


• A need for antennas producing a high angle of radiation, the simplest of which 

would be a horizontal or semi horizontal dipole, not a convenient antenna for 

smaller vehicles or vessels. 

The selection of an optimum frequency for NVIS operation depends upon many variables. 

Among these are time of day, time of year, solar activity, type of antenna used, 

atmospheric noise, and atmospheric absorption. 

NVIS could provide for the shared use of the maritime mobile bands included in 

Appendices 17 and 25 of the ITU Radio Regulations for localised fixed and land mobile 

service operations. It could also be used for broadcasting and other point to point and 

point to multipoint radiocommunication services. Maritime HF communications are 

unlikely to be used at ranges less than 300 km because the MF maritime bands will offer 

a more reliable service. Ship stations receiving from a coast station located within the 

same general area as NVIS communication links being operated on land will therefore be 

beyond the range of those NVIS links. A possibility remains that ship stations operating 

close to the shore using long distance HF communications to contact a shore station in 

their own country may be affected; however, ships should normally operate to the nearest 

coast station for the purpose of public correspondence. Likewise, there is also a potential 

interference problem if the coast station receiving transmissions from a ship, lies within 

range of NVIS fixed/mobile operations. The possibility of shared use of some HF 

frequency bands between localised services using NVIS techniques and medium/long 

range services using low angle launch antennas and oblique angle reflection from the 

ionosphere would therefore appear to be feasible. 

6.6 MF - Communications 

6.6.1 Frequency Allocations (international, Region 1) 

The following bands are available for MF communications in ITU Region 1 and the EMA: 

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• 415-526.5 kHz (primary or co-primary): main use is for MF telegraphy, but also 

NBDP; 

• sub-bands between 1606.5-3800 kHz (primary or co-primary): main use is for MF 

telephony, but also NBDP and DSC. 

A detailed break-down of the frequency sub-bands for coast and ship stations and 

intership use, for single-sideband radiotelephony, NBDB and DSC is given in Article 52 of 

the Radio Regulations. 

The following bands were planned (assignment planning) at the Regional Administrative 

Conference for the Planning of the MF Maritime Mobile and Aeronautical Radionavigation 

Services (Region 1). Geneva, 1985: 

• 415-435 kHz, 435-495 kHz and 505-526.5 kHz for the maritime mobile service 

for Morse telegraphy and NBDP; 

• 1606.5-1625 kHz, 1635-1800 kHz and 2045-2160 kHz for the maritime mobile 

service for SSB telephony and NBDP; 

• 415-435 kHz and 510-526.5 kHz for the aeronautical radionavigation service 

(radiobeacons). 

The frequencies used for distress and safety communications in the Global Maritime 

Distress and Safety System (GMDSS) are: 

• 490, 518, 2174.5, 2182 and 2187.5 kHz; details on their use are specified in 

Appendix 15 to the Radio Regulations. 

The frequencies used for non-GMDSS distress and safety communications are: 

• 500, 518 and 2182 kHz; details on their use are specified in Appendix 13 to the 

Radio Regulations. 

From a United Kingdom perspective there is no congestion in the MF bands used for 

commercial traffic (see also Section 6.6.3). 


The following technologies are utilised in the MF maritime bands: 

• Morse telegraphy, class of emission A1A; 

• narrow-band direct printing (e.g. NAVTEX), class of emission F1B or J2B; 

• digital selective calling (DSC), class of emission F1B or J2B. 

• single-sideband telephony, class of emission J3E, simplex and duplex operation; 

The technology used ranges from techniques which date back to the start of 

radiocommunications, such as Morse telegraphy, to more advanced digital systems, for 

example DSC and NBDP. Due to the international character of the service, progress in 

implementing more modern techniques on a worldwide basis is a slow process. 

Technical characteristics of the equipment can be found in Recommendation ITU-R 

M.476 for NBDP (incorporated by reference in the ITU Radio Regulations), in 

Recommendation ITU-R M.493 for DSC, in Recommendation ITU-R M.540 for NAVTEX 

equipment and in Recommendation ITU-R M.1173 for SSB transmitters (incorporated by 

reference in the RR). 

Due to the international character of the service, agreed operational procedures have to 

be observed. In addition to those contained in Chapter VII and IX of the Radio 

Regulations, relevant requirements can be found in Recommendation ITU-R M.492 for 

NBDP (incorporated by reference in the Radio Regulations), in Recommendation ITU-R 

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M.540 for NAVTEX equipment, in Recommendation ITU-R M.541 for DSC (incorporated 

by reference in the RR), in Recommendation ITU-R M.1170 for Morse telegraphy and in 

Recommendation ITU-R M.1171 for radiotelephony. 


The MF bands are used for medium range communications up to several 100 km, during 

day-time mainly ground wave propagation, at night time mainly sky wave propagation. 

Maritime voice and data ship-to-shore and shore-to-ship communications are a continuing 

requirement. 

The frequency band 415-526.5 kHz is to be used by ships and coast stations for radio 

telegraphy. The maritime use of these bands was previously foreseen to transfer from 

Morse telegraphy to narrow-band direct printing telegraphy (NBDP), but this expectation 

has not as yet been realised. With the exception of two frequencies (490 kHz and 518 

kHz) which are designated for the dissemination of maritime safety information by means 

of NBDP (NAVTEX system), Morse telegraphy has been almost the sole usage in the 

bands at least in Europe. 

Navtex transmissions broadcast information to shipping such as urgent meteorological 

and navigational warnings using radiotelex transmissions. In the UK Navtex transmissions 

are broadcast from three locations, Niton, Cullercoats and Portpatrick. The service uses 

both 490 kHz and 518 kHz and each station transmits at a given time. The transmission 

power for Navtex as recommended by the IMO is 1kW during daylight hours and 300W at 

night. These services have a nominal range of 270nm (500km). Coverage around UK 

waters is augmented by NAVTEX transmitters in the Republic of Ireland, sited at Valentia 

and Malin Head, both with nominal ranges of 400nm. 

Maritime safety information (MSI) is broadcast by MCA stations on the frequencies in 

Table 6-4 below. 

Station Frequency (kHz) 

Solent 1641 

Milford 1767 

Shetland 1770 

Stornoway 1886 

Yarmouth 1869 

Holyhead 1880 

Clyde 1883 

Humber 1925 

Falmouth/Milford 2670 

Aberdeen 2691 

Tyne Tees 2719 

Table 6-4 MSI Frequencies used in the UK 

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The United Kingdom has closed down all coast stations offering a commercial (public 

correspondence) service in all frequency bands because they are no longer economically 

viable. If communications are not established through coast stations of other countries (e. 

g. the Danish coast station Lyngby Radio), the public communications needs of ships are 

mainly met by GSM, if close enough to a base station on land or by satellite (Inmarsat). 

The issue of public correspondence services and the increased use of GSM and satellite 

communications are addressed in more detail elsewhere in this report. 

Apart from the frequencies used for distress and safety, it would appear from a United 

Kingdom perspective that the MF bands that are designated for commercial traffic could 

be released for other services. Due to the international character of the maritime mobile 

service and the need for agreement in the ITU, would be a very time-consuming process 


Coast station equipment for general as well as for distress and safety use has to comply 

with the R&TTE Directive. 

The shipborne equipment has to comply with the R&TTE Directive for equipment used for 

non-SOLAS purposes and with the Marine Equipment Directive concerning equipment for 

distress and safety under the SOLAS Convention; compliance with this Directive 

guarantees automatic compliance with the relevant requirements in the SOLAS 

Convention. 


There is no incentive for any improvements to the existing technology; this applies in 

particular to Morse telegraphy, since its importance is rapidly decreasing (see also 

Section 6.6.3). 


With regard to SSB telephony, it is believed to be premature to consider a change-over to 

digital techniques. As far as the digital modes of operation are concerned, it could be 

envisaged that high-speed data systems in accordance with Recommendation ITU-R 

M.1081 might be implemented. These are presently limited to the HF bands; nevertheless 

they could also be implemented in the MF bands within one telephony channel. 

There is also the possibility to use many of the techniques addressed in section 6.5 within 

the spectrum allocated to the maritime mobile and mobile services between 1.6 and 3 

MHz. Firstly, NVIS propagation characteristics (see 6.5.3) might provide possibilities for 

introducing more services in the range through sharing, however the main technology 

challenges will be the development of antennas for mobile stations with a high launch 

angle. Large vessels will of course be able to install the electrically low horizontal 

antennas best suited for such propagation but this may not apply to smaller ships or land 

vehicles if sharing was to be contemplated. 

The adaptive techniques described in section 6.5.1 are equally applicable to spectrum in 

the range 1.6 – 3 MHz and the Email and data services described in 6.5.2 might also be 

extended to the upper end of the MF frequency band. 

Although WRC-2003 was mandated to review, under its agenda item 1.14, also the 

frequency arrangements in the maritime MF bands concerning the use of digital 

technology, no pertinent decision was taken. 

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Sea area A2 is defined as an area within range of a shore based MF DSC station. This 

varies between 90 km at the low frequency end of the MF range at 300 kHz and 750 km 

at the upper end. Range is also dependent on time of day with the greatest ranges being 

achieved after the hours of darkness. Technologies that might replace MF maritime 

communications include VHF communications, low power HF communications or satellite 

based systems. Mandatory carriage requirements within the range for SOLAS vessels 

include a 2182 kHz watch receiver and an MF radio installation capable of transmitting 

and receiving DSC and radio telephony. 

Public correspondence is no longer provided by UK coast stations and GMDSS DSC 

includes MF at 2187.5 kHz with 2182.0 kHz used as an associated telephony frequency 

with the MF SAR frequency at 2596 kHz. There are then 11 frequencies between 1641 

and 2719 kHz used for MSI broadcasts. Popular MF inter-ship simplex frequencies 

include 2048 kHz, 2065 kHz, 2079 kHz and 2096.5 kHz. 

In principle there would seem to be scope for considering some changes to the way the 

MF band is utilised in the UK especially on any remaining UK allotments within the 1985 

ITU Region 1 Plan for maritime services. However it is unlikely that the 11 MSI 

frequencies could be vacated quickly on safety grounds although safety broadcasts could 

no doubt be accommodated by other means. 

Let us examine the cost of equipping one segment of the maritime industry, perhaps the 

most vulnerable to additional costs; the fishing industry. MF intership voice 

communications has traditionally been used by fishing fleets to maintain contact with 

other vessels as well as for other safety related activities. The 2002 Department for 

Environment, Food and Rural Affairs (Defra) list of registered UK fishing vessels includes 

945 fishing vessels greater than 10 metres and 3598 vessels less than 10 metres. Let us 

assume around 4500 in total. Most vessels of less than 10 metres would fish within VHF 

range of each other and would probably be within VHF range of the coast. Many vessels 

would also be already fitted with VHF maritime equipment. Vessels of over 10 metres in 

length are more likely to operate in fishing grounds remote from the UK and may require 

the extended range of MF but in this case they would be remote from the UK. 

In summary many of the communications requirements of inshore fleets might be 

accommodated at VHF but in later sections we will also be examining the same question, 

the cost of alternative means of communication in respect of alternatives to VHF. In terms 

of commercial and safety communications it is feasible that low data rate satellite 

communications could provide a replacement and it is likely that this would need to be 

additional expenditure for most fishing vessels. Equipment costs would be in the order of 

£ 2500 however a ship owner would need to pay for installation registration charges and 

monthly usage rates. This is likely to be a total replacement cost to the industry of around 

£15M. 

A cheaper option could be to use foreign automatic MF/HF maritime Email services 

especially if they become accepted as part of the GMDSS in which case a modern HF 

transceiver with DSP and computer control would be required. A large upfront initial 

expenditure of around £3000 – £4000 would be required. There would again be 

subscription charges and the cost of messages but these are less than the cost of circuit 

switched satellite connections. 

In reality there is probably no substitute for basic distress MF DSC/telephony and intership 

voice telephony on a small fishing vessel with the comfort of being able to solicit 

advice and help from friends and colleagues in a difficult situation. 

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In section 6.3.9.5 we have already examined whether maritime spectrum below the MF 

broadcasting band might be of interest to broadcasters. As was stated there, DRM is a 

new broadcasting technology development and could be implemented in new frequency 

bands as well as in the more traditional LF and MF bands. It might therefore be possible 

to introduce such networks in spectrum below 526.5 kHz if the requirement for 

aeronautical NDBs starts to diminish in the UK by 2010 as expected as GNSS systems 

come on stream and the integrity of residual maritime distress and safety requirements 

can be protected until they are no longer required. It should however be noted that ICAO 

considers NDBs may be required until 2020. 

DRM was designed as an in-band technology rather than an occupier of new spectrum, 

nevertheless there could be interest in the band from broadcasters and potential 

broadcasters. As mentioned earlier the economics of such stations and the available 

advertising revenues may have to be addressed. 

It is also likely that the Radio Society of Great Britain (RSGB) might propose that an 

allocation to the amateur service in the vicinity of 500 kHz would be worthy of 

consideration. An allocation between the lowest allocation to the amateur service at 136 

kHz and their allocation at 1810 kHz might provide this service with a useful spectrum 

addition and encourage study in low frequency propagation mechanisms. A spokesman 

from the International Amateur Radio Union (IARU) has confirmed that there would be 

interest in an allocation somewhere between the two lowest amateur allocations 


The introduction of more modern digital systems in the MF radiotelephony bands would 

increase overall spectrum efficiency (see Section 6.6.6). Because of the decreasing use 

of the MF telegraphy band, also on the international level, it seems possible for the 

maritime mobile service to give up this band in the long term with the exception of those 

few frequencies that are used for GMDSS and non-GMDSS distress and safety 

communications (490, 500 and 518 kHz). But this will be a very slow process and will 

certainly find opposition from less developed countries. An exhaustive review of the band 

415-526.5 kHz is therefore highly desirable. 

6.6.10 Socio-Economic Issues 

The GMDSS was developed by the International Maritime Organisation (IMO) and 

supported by the ITU as the worldwide Distress and Safety communications system. In 

the UK the MCA is responsible for its implementation. The GMDSS became operational in 

1991 and on 1st February 1999 became a compulsory requirement for all Safety of Life at 

Sea (SOLAS) convention vessels; that is vessels over 300 gross registered tons and 

various classes of passenger and fishing vessels. 

The implementation of the GMDSS has highlighted the importance of ensuring that 

Maritime radio is correctly licensed. Details of a licensee's vessel, emergency contact etc. 

is made available to HM Coastguard and may be used to facilitate a search and rescue 

operation. All DSC radios (both in coast and ship stations) must be programmed with a 

Maritime Mobile Service Identity (MMSI) number, which uniquely identifies the station. 

MMSIs have a standard format, which identifies the type of station and country of 

registration. Vessel MMSI numbers are issued in the United Kingdom by the Radio 

Licensing Centre on behalf of Ofcom. Local offices of Ofcom, as part of the licensing 

process, issue Coastal Station Radio MMSIs. It is crucial that only MMSIs issued by 

Ofcom or the Radio Licensing Centre on their behalf are programmed into DSC 

equipment (as the MMSIs are registered with the ITU). The use of incorrect numbers 

could mean that the Search and Rescue services might deploy inappropriate resources in 

response to a distress call thereby compromising their effectiveness. 

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The feasibility of utilising alternative communications for small commercial vessels has 

been addressed in previous sections in order to ascertain a possible value for MF 

maritime spectrum. It is at this point that it is pertinent to refer to the Government's 

response to the Environment, Transport and Regional Affairs (ETRA) Committee's report 

'The Future of the UK Shipping Industry'. The Government has stated that action is now 

needed in order to reverse the decline in the UK shipping industry, and welcomed the 

Committee's general support of the Government's shipping policy paper, 'British Shipping: 

Charting a new course', which was designed to initiate the required action. The policy 

paper outlined the Government's strategy for securing the future of the UK shipping 

industry in the form of 33 action points designed to develop the UK's maritime skills, 

secure British seafaring employment, enhance the UK's attractiveness to shipping 

enterprises, and gain safety and environmental benefits. The ETRA recommended that 

urgent action should be taken both to increase the number of vessels on the UK register, 

and to increase the number of British seafarers. The Government agreed responding that 

two of the central aims of the Government's shipping policy were to encourage UK ship 

registration and to promote the employment and training of British seafarers. The 

Government's shipping policy paper sets out a number of actions designed to develop a 

shipping environment in which UK shipping companies would be encouraged to develop 

their shipping operations and register their vessels in the UK, and to develop the UK's 

maritime skills base by employing and training increasing numbers of British seafarers. 

Any policy developed for AIP which is based on the cost of alternative technology, which 

is significantly higher than the costs of the currently utilised technology may have an 

adverse impact on the registration plans of ship and fleet owners. This may particularly 

apply to the fishing fleet which as a consequence of declining fish stocks and necessary 

preservation measures has suffered badly in recent years. 

In many cases at MF and at HF and VHF the alternative communications mechanism for 

voice telephony is always commercial satellite providers with attendant equipment, space 

segment and registration costs. Fishing fleets rely heavily on MF inter-ship voice 

communications especially when out of VHF range of the coast and other fleet members. 

Distress and safety requirements might be handled more effectively using cost effective 

commercial data communications based on adaptive HF technology if the IMO approve 

such systems for participation in the GMDSS. However there would also be a need to 

update equipment and pay for the use of the service. 

Digital MF systems could be introduced on a national and non-interference basis without 

jeopardising the interoperability with ships from foreign countries. Introduction of new 

technology would in the long run require worldwide harmonisation in the ITU which is a 

cumbersome and time-consuming process with very long lead-times for the transition to 

new technologies. Developing countries are normally reluctant to changes due to the cost 

implications. On a national basis, new technologies could be introduced on a trial basis, 

but as has been pointed out before, there does not seem to be an incentive for the United 

Kingdom to embark on such an initiative. 

Another difficulty is that coast station equipment is only required in very small quantities 

with the consequence that economies of scale cannot be achieved, irrespective of 

whether conventional or more advanced technology, that better meets the needs of the 

user, is employed. 

It would therefore seem opportune for the United Kingdom to seek an in-depth European 

review of LF, MF and probably HF spectrum as well with a view to ascertaining European 

current and future requirements and to make the necessary recommendations and plans 

for the future. This could be achieved through a proposal for an additional phase of the 

Detailed Spectrum Investigation (DSI) process which has been a feature of European 

spectrum management since 1991. With a European approach, economies of scale can 

be achieved for regional solutions to regional requirements. Spectrum plans for the 

introduction of new technologies can also take account of the needs of existing services 

Page 216

in an appropriate manner. Last but not least a unified European position within the IMO 

and ITU can help significantly in the achievement of UK objectives. 

The United Kingdom was by no means insignificant in achieving the European approach 

to radiocommunications that we have today. This now needs to be built upon to effectively 

manage this valuable resource to the benefit of all. Proposals for change must therefore 

be discussed openly in a transparent manner to determine whether or not envisaged 

pricing arrangements will have a negative or positive impact on the UK maritime industry 

as a whole. It will then have to be determined whether an incentive administrative pricing 

regime for maritime authorisations will need to include an element which will reflect the 

economic value of maintaining and extending the UK register of shipping. 

Recommendation 6.3: Very little use is made of the MF telegraphy band. Narrowband 

direct printing has not replaced Morse telegraphy as was expected to happen. 

Except on 490 and 518 kHz, and on 500 kHz which despite full implementation of the 

GMDSS has maintained a certain safety and distress function in some areas of the world, 

there is little traffic in the band 415-526.5 kHz. It is therefore recommended that an in 

depth and careful review of this band should be initiated with a view to allocate a 

significant part of it for other applications. This could be part a European overall spectrum 

review (DSI) covering LF, MF and HF spectrum, see also Recommendation 6.2 above. 

Recommendation 6.4: Subject to the results of public consultation and any 

European DSI process (see Recommendation 6.2 above) it is recommended that new 

digital systems in the 2 MHz MF band should be considered on a national and noninterference 

basis taking account of the need to maintain interoperability with ships from 

foreign countries. 

6.7 HF Communications 


The following bands are available for maritime HF communications: 

• 4, 6, 8, 12, 16, 18/19, 22 and 25/26 MHz 

Appendix 17 to the Radio Regulations contains the detailed frequencies and channelling 

arrangements in the HF bands between 4000 and 27500 kHz allocated exclusively to the 

maritime mobile service. The 3 lower frequency bands are particularly important for 

maritime communications as they generally provide reliable night time communications at 

any time in the solar cycle, except in periods of high geomagnetic activity in temperate 

and northerly/southerly latitudes. Detailed charts of the 4, 6 and 8 MHz bands can be 

found at Annex 5. 

Frequencies are available for: 

• ship stations for oceanographic data transmission; 

• ship stations for telephony, duplex operation; 

• ship and coast stations for telephony, simplex operation; 

• ship and coast stations for telephony, duplex operation; 

• ship stations for wide-band telegraphy, facsimile and special transmission 

systems; 

• ship stations (paired) for NBDP telegraphy and data transmission systems at 

speeds not exceeding 100 Bd for FSK and 200 Bd for PSK; 

• ship stations for calling in Morse telegraphy; 

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• ship stations for working in Morse telegraphy; 

• ship stations (non-paired) for NBDP telegraphy and data transmission systems at 

speeds not exceeding 100 Bd for FSK and 200 Bd for PSK and for Morse 

telegraphy (working); 

• ship stations for DSC; 

• coast stations (paired) for NBDP telegraphy and data transmission systems at 

speeds not exceeding 100 Bd for FSK and 200 Bd for PSK; 

• coast stations for DSC; 

• coast stations wide-band and Morse telegraphy, facsimile, special and data 

transmission systems and NBDP telegraphy; 

• coast stations for telephony, duplex operation; 

• initial testing and the possible future introduction within the maritime service of 

new digital technologies (Appendix 17to the RR, Part A, note p to the table). 

Appendix 25 to the Radio Regulations contains the provisions and the associated 

frequency allotment Plan for coast radiotelephone stations operating in the exclusive 

maritime mobile bands between 4 000 kHz and 27 500 kHz. 

There are a number frequencies used for distress and safety communications in the 

GMDSS in the 4, 6, 8, 12, 16, 18/19, 22 and 25/26 MHz bands. Details of their use are 

specified in Appendix 15 to the Radio Regulations. 

Other MSI broadcasts for ships at greater ranges are transmitted from the UK on the 

following frequencies in the HF bands, termed high sea NBDP MSI transmissions from 

coast stations – 4210 kHz, 6314 kHz, 8416.5 kHz and 12579 kHz. 

The frequencies used for non-GMDSS distress and safety communications are: 4125, 

6215 and 8364 kHz; details of their use are specified in Appendix 13 to the Radio 

Regulations. 

From the United Kingdom perspective there is no congestion in those HF bands used for 

commercial traffic (see also Section 6.7.3). 


• Morse telegraphy, class of emission A1A; 

• narrow-band direct printing, class of emission F1B or J2B; 

• digital selective calling (DSC), class of emission F1B or J2B; 

• single-sideband telephony, class of emission J3E, simplex and duplex operation; 

• narrow and wideband data transmission, class of emission F1B or J2B. 

The technology used ranges from Morse telegraphy, to more advanced systems, such as 

DSC, NBDP and wideband data transmission. Due to the international character of the 

service, progress in implementing more modern techniques on a worldwide basis is slow. 

Technical characteristics of the equipment can be found in Recommendation ITU-R 

M.476 for NBDP (incorporated by reference in the RR), in Recommendation ITU-R M.493 

for DSC, in Recommendation ITU-R M.625 for NBDP equipment employing automatic 

identification (incorporated by reference in the RR), in Recommendation ITU-R M.627 for 

NBDP equipment using NBPSK (incorporated by reference in the RR), in 

Recommendation ITU-R M.688 for direct-printing telegraph systems for promulgation of 

high seas and NAVTEX-type safety information, in Recommendation ITU-R M.1081 for 

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automatic facsimile and data systems and in Recommendation ITU-R M.1173 for SSB 

transmitters (incorporated by reference in the RR). 

Due to the international character of the service, agreed operational procedures have to 

be observed. In addition to those contained in Chapter VII and IX of the Radio 

Regulations, relevant requirements can be found in Recommendation ITU-R M.492 for 

NBDP (incorporated by reference in the RR), in Recommendation ITU-R M.541 for DSC 

(incorporated by reference in the RR), in Recommendation ITU-R M.1170 for Morse 

telegraphy, in Recommendation ITU-R M.1171 for radiotelephony and in 

Recommendation ITU-R M.1081 for automatic HF facsimile and data systems. 


The HF bands are used for terrestrial international long range ionospheric 

communications with worldwide coverage. 

Maritime voice and data ship-to-shore communications is a continuing requirement. 

However, according to our investigations, the United Kingdom has closed down all coast 

stations offering a commercial (public correspondence) service, because they are no 

longer economically viable. If HF communications are not established through coast 

stations of other countries, e. g. the Danish coast station Lyngby Radio, long-distance 

communication needs of ships are met via satellite (Inmarsat). ESVs offer also an 

alternative for larger ships - this matter is addressed in more detail in section 6.14.6. 

Apart from the HF frequencies used for distress and safety, it would seem seen from a 

United Kingdom perspective, that the maritime HF bands could be reused for more 

advanced applications. It is however doubtful, whether there would be sufficient incentive 

for a potential United Kingdom coast station operator to invest money to provide such 

new services. Due to the international character of the maritime mobile service the 

process of re-farming the HF maritime bands has to be agreed in the ITU, and is likely to 

be a very cumbersome and time-consuming process. 

It can be summarised that the importance of HF maritime communications is gradually 

decreasing because of alternative systems to meet the needs of the shipping industry, 

e.g. the Inmarsat system at 1.5/1.6 GHz and ESVs. The situation may change if new 

technologies offer new communication possibilities, which do not exist at present. 


Coast station equipment for general as well as for distress and safety use has to comply 

with the R&TTE Directive. 

Shipborne equipment has to comply with the R&TTE Directive for equipment used for 




Convention. 

We should at this point mention an important regulatory matter that will impact all services 

utilising spectrum between 4 and 10 MHz with exception of the band 7,000.0 – 7,200.0 

kHz. National administrations and regional bodies such as CEPT are already addressing 

agenda item 1.13 of the ITU World Radio Conference to be held in 2007. This agenda 

item provides for a review of the spectrum and the Plans incorporated into the Radio 

Regulations for both aeronautical and maritime services. The review will consider the 

impact of new technologies and their impact on radiocommunications services. 

There is no incentive for any improvements to the existing Morse telegraphy and SSB 

radiotelephony technologies since their importance is rapidly decreasing. Improvements 

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might be effected through the implementation of completely new technologies (digital, 

adaptive systems, see Section 6.7.6. 


There is also the possibility to use many of the techniques addressed in section 6.5 within 

the spectrum allocated to the maritime mobile and mobile services between 4 and 10 

MHz. Firstly, NVIS propagation characteristics (see 6.5.3) might provide possibilities for 

introducing more services in the range through sharing, however the main technology 

challenges will be the development of antennas for mobile stations with a high launch 

angle. Large vessels will of course be able to install the electrically low horizontal 

antennas best suited for such propagation but this may not apply to land vehicles if 

sharing was to be contemplated. 

a) Digital technology 

WRC-97 considered that it would be desirable to extend the use of digital technology to 

the maritime HF A1A Morse telegraphy bands since these bands were significantly 

underutilised and that the requirement for the use of new digital technologies in the 

maritime mobile service was growing rapidly. Consequently, the WRC adopted 

amendments to the Radio Regulations to provide for the use of digital telecommunication 

technology in the maritime HF telephony and A1A Morse bands. It noted that the use of 

the maritime HF A1A Morse radiotelegraphy bands was steadily diminishing with the 

result that administrations were already beginning to use these bands for digital systems 

on a non-interference basis. It is known that in some countries internet (email) services 

are being implemented on these frequencies. 

WRC-2003 reviewed, under its agenda item 1.14, the frequency and channel 

arrangements in the maritime MF and HF bands concerning the use of digital technology, 

also taking account of Resolution 347 (WRC-97, subsequently abrogated at WRC-2003) 

of the Radio Regulations. Consequently, it revised Appendix 17 to the RR to allow for 

initial testing and the possible future introduction within the maritime service of new digital 

technologies (Appendix 17, Part A, note p to the table). In its Resolution COM4/2 it 

considered that the need to use new digital technologies in the maritime mobile service is 

growing rapidly and that the use of new digital technology on maritime HF and MF 

frequencies will make it possible to respond better to the emerging demand for new 

services. ITU-R is already conducting studies to improve the efficient use of these 

maritime bands. These studies can benefit from different digital technologies developed 

for other services. ITU-R has been requested by WRC-2003 to finalise these ongoing 

studies urgently including proposing a timetable for the introduction of these new digital 

technologies. 


implementing national solutions that might not be compatible with future systems. 

With regard to SSB telephony, it would seem premature to consider a change-over to 

digital techniques. In the longer term a transition to digital techniques, perhaps similar to 

that use for digital HF broadcasting, may be advocated. 

b) Adaptive systems 

Adaptive technology is addressed in detail in section 6.5.1. This is certainly another area 

that might offer opportunities to the maritime HF community and at the same time make 

much better use of the available frequency spectrum is adaptive systems. Adaptive 

systems are systems which can automatically select the optimum channel from an 

assigned group, which release the channel when no traffic is present, thus allowing 

frequencies to be shared more effectively and efficiently, reducing interference between 

users and providing the ability to increase traffic density. Adaptive systems make it 

possible to achieve a higher quality of service by combining an ability to exploit modern 

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adio-frequency technology with advanced real-time control software. The result is a 

system which is reliable, robust, cost-effective and easy to use. Frequency-agile, adaptive 

HF systems may be used for any type of fixed or mobile service, but have a greater 

capability for digital technologies where a high quality is required. An adaptive system 

automates the process involved in establishing, maintaining and terminating HF links. 

There is no need for skilled operators the quality of service and the efficiency of the link is 

improved. 

An adaptive system has a triple function, firstly automatic selection of the frequency and 

of other system parameters to be used, secondly automatic operation as regards calling 

and thirdly establishing the communications path and disconnecting the adaptive function 

during the communication so as to optimise at all times the quality of service with respect 

to the ionospheric conditions and spectrum congestion. Some adaptive systems have the 

capability to monitor the channel prior to utilisation and assess the channel quality on a 

periodic basis. This capability enables the adaptive system to avoid the use of channels 

which have a limited utility and it also reduces the probability of interference to other 

users of the spectrum. One current application which uses adaptive techniques is the 

various operators which offer an automated E-mail service including the transmission of 

binary files and graphics. Such systems are covered in section 6.5.2 above. 

Studies are ongoing in the ITU-R; they focus inter alia on grade of service, efficient use of 

spectrum, minimisation of interference and better access to the spectrum (see e.g. 

Question ITU-R 205-1/9, Recommendations ITU-R F.1110 and SM.1266). 


Adaptive systems have been successfully introduced in the fixed service in the HF bands. 

They would likewise offer great advantages to the maritime mobile service in the MF (see 

section 6.6.6) and HF bands. The implementation of adaptive systems on frequencies 

listed in Appendix 17 to the Radio Regulations is permitted for initial testing through note 

p to the table in Part A of the Appendix. Frequencies from outside the maritime bands 

could of course be added to the group of frequencies used. It is of course well understood 

that the final introduction of this new technology in the maritime mobile service requires 

further in-depth studies and the adoption of appropriate technical and regulatory 

provisions. It is therefore recommended, that regulatory pre-conditions are developed for 

the implementation of such adaptive techniques along the lines described above. 


Use of CB equipment (around 27 MHz) might be considered as a cheap alternative for 

small boats for general communications and also in a limited way for safety and distress 

alerting and communications. According to information received from the United Kingdom 

Coastguard, they currently do not monitor any CB channel nor do they have plans to do 

so. The situation in Germany is exactly the same. Information from other European 

countries has not been found. Australia has however used spectrum in the vicinity of the 

CB band for such an application. Details are provided in Table 6-5. 

Frequency Application in Australia 

27.680 MHz Ship to ship/ ship to shore Calling and working 

27.720 Professional fishing. Calling and working/ ship to ship and ship to shore 

27.820 As 27.720 

27.860 Secondary DISTRESS, safety and calling 

27.880 Primary DISTRESS, safety and calling 

27.900 Calling and working ship to shore 

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27.910 As 27.900 

27.960 Calling and working ship to ship 

27.980 Rescue organisations such as, Surf Rescue Ship to ship/ship to shore 

Table 6-5 Australian Maritime 27 MHz frequencies 

With the decline in use of CB frequencies and the relative low price of equipment, the 

possibility of utilising this part of the spectrum for small boats should be kept in mind if 

additional spectrum resources are considered necessary in the future for this category of 

user. For the time being, this issue should not be pursued any further. 


NVIS propagation techniques described in section 6.5.3 may provide for the shared use 

of maritime mobile bands in the range 4 – 10 MHz. These could be envisaged for 

localised fixed and land mobile service operations. Whether there is a requirement for 

such HF fixed and mobile services in the UK is largely irrelevant since there is a 

requirement for such services in many developing countries. If their needs can be 

satisfied at World Radio Conferences benefits may accrue to Europe in the satisfying of 

other requirements. There is one problem already mentioned; NVIS relies on transmitting 

and receiving emissions at an angle of radiation near 90 degrees. Antennas are relatively 

simply such as a horizontal dipole mounted close to ground level, however such antennas 

are not generally capable of being mounted on small moving vehicles, for example a half 

wave dipole at 10 MHz is some 15 metres in length. On the other hand short (in terms of 

wavelength) vertical whips, either loaded or tuned can be mounted on vehicles but the 

angle of launch is rather low, thus the full effects of NVIS may not be realised and sharing 

may prove to be more difficult. It would therefore seem that fixed services would be better 

sharing partners than land mobile services. 

On the assumption that antenna problems can be overcome, Maritime HF 

communications are unlikely to be used at ranges less than 300 km because the MF 

maritime bands will offer a more reliable service. Ship stations receiving from a coast 

station located within the same general area as NVIS communication links being operated 

on land will therefore be beyond the range of those NVIS links. A possibility remains that 

ship stations operating close to the shore using long distance HF communications to 

contact a shore station in their own country may be affected; however, ships should 

normally operate to the nearest coast station for the purpose of public correspondence. 

Likewise, there is also a potential interference problem if the coast station receiving 

transmissions from ships lays within range of NVIS fixed/mobile operations. 


The introduction of modern digital systems in the HF maritime bands will increase the 

overall spectrum efficiency (see Section 6.7.5). Despite the obvious decrease in the traffic 

handled on HF, it seems premature to suggest the release of part of the maritime 

spectrum to other services despite the heavy demand from e.g. the broadcasting service, 

the fixed and land mobile services and defence systems. Additional sharing may however 

be possible. 

On the one hand, innovative applications and technology might make the HF bands much 

more attractive than they currently are at present and as indicated below HF maritime 

systems may prove to be a cost effective alternative to the current generation of maritime 

mobile satellite communications. 

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6.7.9 Socio-Economic Issues 

The issues outlined in section 6.6.10 concerning MF communications are generally 

applicable here. However the newer automated HF systems already seem to offer a 

viable and cost effective alternative to satellite communications. Although operated by 

commercial entities there is a need to exploit the entrepreneurial nature of the systems 

but at the same time developing the means to provide competition and diversity in order 

to ensure a reliable and long term service. This is especially important if such services are 

recognised as providing an acceptable and approved alternative for the GMDSS. 

Other new digital systems could be introduced on a national and non-interference basis 

without jeopardising the interoperability with ships from foreign countries. It is envisaged 

that the introduction of new digital technologies will be only possible on a medium to longterm 

basis. A change of the HF frequency and channel arrangements will have serious 

cost implications and in particular developing countries will find it difficult. On the other 

hand with present modern synthesizer equipment, a frequency change within a given 

band is not a major issue. As long as enough bandwidth for the modes of operation 

presently used is preserved to meet the needs of developing countries, there should not 

be too much resistance for a gradual change. 

Recommendation 6.6: In the HF bands, there is a rapidly growing need for digital 

technologies. Appendix 17 to the Radio Regulations, allows for initial testing and the 

possible future introduction within the maritime service of new digital technologies. The 

ITU-R is already conducting studies to improve the efficient use of these maritime bands. 


implementing national solutions that might not be compatible with the outcome of these 

studies. With regard to SSB telephony, it is believed premature to advocate a changeover 

to digital techniques. In the longer term a transition to digital techniques, perhaps 

similar to those envisaged for digital HF broadcasting, may be considered. 

6.8 VHF – Communications (International) 


International VHF maritime communication is located in the sub-bands 156.0125- 

157.4375 MHz and 160.6125-162.0375 MHz from within the band 156-174 MHz allocated 

to the mobile service on a primary basis. The frequencies and their conditions of use are 

specified in Appendix 18 to the Radio Regulations (Table of transmitting frequencies in 

the VHF maritime mobile service). Appendix 18 provides for 59 channels (1-28, 60-88, 

AIS1, AIS2) to be used for: 

• ship and coast stations; 

• single-frequency or two-frequency operation; 

• inter-ship, port operations and ship movement, public correspondence; 

• digital selective calling for distress, safety and calling (exclusive use of channel 

70); 

• distress, safety and calling (exclusive use of channel 16); 

• automatic ship identification and surveillance (exclusive use of channels AIS 1 

and 2; see also Section 6.10); 

For further details, see Appendix 18. 

Apart from DSC and AIS, the main use is for radiotelephony. However, certain channels 

can also be used for direct-printing telegraphy, data and facsimile transmissions. 

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The frequencies used for distress and safety communications in the GMDSS are (for 

details see Appendix 15 to the Radio Regulations): 

• 156.3 MHz for communication between ship and aircraft stations engaged in coordinated 

search and rescue operations; 

• 156.525 for distress and safety calls using DSC, also used by DSC VHF EPIRBs 

although none have been manufactured to date; 

• 156.650 MHz for ship-to-ship communications relating to the safety of navigation; 

• 156.800 MHz for distress and safety communications by radiotelephony. 

The frequencies used for non-GMDSS distress and safety communications are (for 

details see Appendix 13 to the Radio Regulations): 

• the same frequencies as above for GMDSS with the exception of 156.525 MHz, 

since distress alerting is by radiotelephony on 156.800 MHz and not by DSC. 

The United Kingdom does not operate coast stations for public correspondence purposes. 


• radiotelephony, class of emission F3E or G3E; 

• narrow-band direct printing, class of emission F2B or G2B; 

• digital selective calling (DSC), class of emission F2B or G2B; 

• automatic identification (AIS, see Section 6.10) 

The channel spacing is 25 kHz. However with the prior agreement of affected 

administrations and administrations having an urgent need to reduce local congestion 

may apply 12.5 kHz channel interleaving on a non-interference basis to 25 kHz channels, 

provided that certain conditions are met, inter alia that Recommendation ITU-R M.1084 is 

observed. For further details see Section 6.8.5. 

Technical characteristics of equipment can be found in Recommendation ITU-R M. 489 

(VHF radiotelephone equipment, incorporated by reference in the Radio Regulations), in 

Recommendation ITU-R M. 493 (DSC) and in Recommendation ITU-R M. 693 (DSC VHF 

EPIRB). Due to the international character of the service, agreed operational procedures 

have to be observed. In addition to those contained in Chapters VII and IX of the Radio 

Regulations, relevant requirements can be found in Recommendation ITU-R M. 541 

(DSC, incorporated by reference in the Radio Regulations) and in Recommendation ITU- 

R M. 1171 (radiotelephony). 


VHF maritime services are extremely important international services which are used for 

distress and safety, calling and communications, ship movement and navigation, port 

operations, inter-ship communications and public correspondence applications. VHF 

maritime services are also a fundamental part of the GMDSS. Maritime VHF 

communications serve a variety of short-range communication needs up to a range of 

abut 50 km, in particular in coastal waters and in port areas. VHF voice and data ship-toshore, 

shore-to-ship and ship-to ship communications are a continuing requirement. 

However, due to the availability of alternative systems, e.g. GSM and satellite systems, 

public correspondence is, at least in Europe, rapidly decreasing. For this reason, the 

United Kingdom has closed down all coast stations offering a commercial service (public 

correspondence). 

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The further development of GSM and IMT-2000 will certainly have an impact on voice 

telephony in particular with leisure vessels operating in coastal waters. Given the 

international aspect of transport, major growth can be contributed to GSM cellular digital 

communications. On the other hand it is recognised that GSM is inappropriate for ships 

trading internationally. These ships need globally available satellite links. 

Regarding satellite communications further growth in the implementation of satellite 

telephony systems for public correspondence is expected. At this moment however, 

satellite telephony communications is only a relatively small part of the total 

communications pattern of a vessel for operational ship-to-shore communications, due to 

the high cost of the equipment and air-time. For public correspondence, satellite 

telephony has already played a significant role in this type of communications and further 

growth is likely. 

Although GSM and satellite communications have caused a decrease in the use of 

maritime frequencies, they will never be a complete alternative for the maritime 

radiotelephone since a large proportion of maritime services require “point-to-multipoint” 

communications instead of a “point-to-point” mode of operation. 

This leaves a dilemma for mariners, there obviously remains a requirement for public 

correspondence especially on passenger and leisure vessels yet there is no maritime 

service. An additional consideration is that with perhaps the exception of the Straits of 

Dover, ships sailing near to the United Kingdom coast-line can normally not use, as is the 

case in the MF bands, VHF coast stations of other countries. However by accident or 

design GSM coverage is often adequate at times of greatest need, at the start and end of 

a journey. 

Much of the above was predictable from a survey of CEPT administrations carried out by 

the European Radiocommunications Office (ERO) of CEPT in 1996. Administrations were 

asked their views on how current maritime use (in 1996) would develop in the future 

including the impact of PCS. Within the responses from administrations two trends were 

evident. Firstly, there was an indication that a move towards the usage of satellite 

communications was generally foreseen. This was due to the implementation of GMDSS 

systems in vessels and the widespread use of the Inmarsat-C system for GMDSS. 

Inmarsat-C could also be used for data communications purposes, which would in turn 

tend to decrease the usage (in 1966) of radiotelegraphy and Morse in the MF band and 

would also decrease the use of HF bands for ship to shore communications. 

The second trend was the application of personal communications systems (either by 

cellular services or by satellite communication systems). It was foreseen that this would 

have a major effect on public correspondence provision. 

However administrations also reported an increasing number of ship movements and 

cited a need for additional VHF channels for short distance maritime and inland waterway 

transport in ship-shore communications. It was suggested that the net result would be that 

some channels in the VHF band used for public correspondence would be re-used for 

ship-to-shore communications, whilst certain services in the MF and HF bands, (i.e. 

radiotelegraphy and Morse) would diminish but not disappear in the coming years. 


Coast station equipment for general and for distress and safety use has to comply with 

the R&TTE Directive. 

The shipborne equipment has to comply with the R&TTE Directive for equipment used for 




Convention. 

Page 225


In recent years the Appendix 18 channels have been severely congested in some regions 

of the world. The concept of alleviating the situation through the introduction of innovative 

technology has been postulated, with some advocating a reduction in channel spacing to 

12.5 kHz whilst others including the United Kingdom suggesting a move to narrow-band 

spectrally efficient digital technologies. The ensuing debate was reminiscent of 

discussions in the aeronautical sector concerning the move to 8.33 kHz channelling and 

whether or not to digitise. In the absence of an international agreement it has been left 

that administrations having an urgent need to reduce local congestion may apply 12.5 

kHz channel interleaving on a non-interference basis to 25 kHz channels under certain 

conditions. The situation is similar to that which prevailed when the channel spacing was 

reduced from 50 to 25 kHz some thirty years ago. However with the reduction in public 

correspondence traffic and the use of GSM in coastal areas, congestion may now have 

reduced to an acceptable level and other factors may now require consideration. It should 

be borne in mind in this connection that the United Kingdom no longer operates VHF 

coast stations open for public correspondence. 

Recommendation ITU-R M.1084 provides interim solutions for improved efficiency in the 

use of the band 156-174 MHz by stations in the maritime mobile service. It offers a 

number of alternative solutions to go from the present 25 kHz channel spacing to 12.5, 

6.25 and 5 kHz channels. In view of the fact that more modern systems are being studied 

in ITU-R with preliminary results already available, it is suggested that the interim method 

chosen, if required for reasons of congestion, should in no way prejudice the 

implementation of the longer term solution resulting from the on-going studies which may 

result in the use of advanced technologies and channel spacing other than 12.5 kHz. In 

summary, if required, an interim system with interleaved narrow-band channels at 12.5 

kHz offset spacing using conventional FM technology with characteristics as specified in 

Annex 3 of Recommendation ITU-R M.1084 may be implemented. 

However, it would be preferential to wait for a more advanced digital system as outlined in 

Section 6.8.6. 


The long-term requirement within the international community is for an advanced 

spectrally efficient digital system to provide improved efficiency in the use of the band 

156-174 MHz. Digital technologies offer a variety of advantages in terms of frequency 

efficiency, quality of service and equipment costs. The great success of GSM would have 

never been possible in an analogue environment. The dramatic decrease of equipment 

price has only been possible with digital technologies. It is therefore obvious that the 

maritime service should also benefit from this technological development. 

The transition to digital technologies must be implemented in such a way that distress and 

safety communications in the maritime VHF band are not disrupted and that the new 

system is able to co-exist with existing equipment. Transition from the present FM system 

to a fully digital system will pose serious problems in maintaining the required grade of 

service because the systems are completely incompatible with each other as opposed to 

a transition within an FM system with a reduction of channel spacing. In particular, the 

availability of all functions of the GMDSS must be guaranteed without any disruption. The 

transition will therefore only be a gradual one with long periods of operational overlap. 

Studies on digital maritime VHF systems are underway in ITU-R; partial answers can be 

found in Recommendation ITU-R M.1312. They are not yet that advanced that any 

recommendation in the context of this study can be given on possible system 

characteristics. In particular, further study is required into the question of whether the 

future digital system should be a narrow-band system with e.g. 8.33 kHz channel spacing 

or a TDMA system with a given number of traffic channels per RF carrier similar to GSM 

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or TETRA. Also the integration of GMDSS functions into a digital system has to be 

carefully studied. It will therefore take quite some time, for a final technical solution to 

become available. 

In summary, it is our view that the future of maritime VHF communications is digital and 

preference should be given to this development. Interim systems along the lines of 

Section 6.8.5 should therefore only be implemented if absolutely necessary from the 

viewpoint of unacceptable congestion of the Appendix 18 channels or when required to 

satisfy the needs of other potential users of the spectrum. It is our belief from the material 

available that due to the closure of commercial communications (public correspondence) 

there is as a result considerable relief in congestion. Appendix 18 already takes account 

of this trend and provides for the use of all public correspondence channels for port 

operations. 


VHF maritime communications is generally considered to have a range of about 35 to 100 

km. In looking at replacement technologies for non GMDSS or other distress and 

emergency related communications, there are generally only three options, MF and HF 

maritime communications, satellite communications and any coverage provided by 

commercial GSM or other public mobile operators. At the extremity of the working range, 

in open waters the GSM option is probably not generally available. Satellite costs would 

be high for inter-ship communications and public correspondence using voice 

communications. MF and HF services should be available and may be developed using 

new technologies along the lines discussed in earlier sections; they may also be provided 

by commercial operators in other countries. GMDSS requirements can of course be 

realised by MF or an Inmarsat-C capability. 

However as a vessel moves towards the coast and its destination the need for 

communications becomes greater, there is more congestion in the sea lanes, ships will 

need to communicate with on-shore services, port operations etc and passengers and 

crew will be looking for public telecommunications services. Within 5 -10 km of a port 

there is likely to be GSM or IMT-2000 coverage and thus this mode of communications 

may be considered an option for placing a value on VHF maritime spectrum. Qualifying 

factors will have to be included in formulating a value, for example whether GSM quality 

of service criteria matches the immediacy requirements for port operations traffic. 


The spectrum identified in Appendix 18 to the Radio Regulations, with the exception of 

156.8 MHz is allocation the mobile, except aeronautical mobile (R), service. Footnotes to 

the ITU table of frequency allocations require administrations to give priority to the 

maritime mobile service. It is nevertheless possible to consider sharing arrangements 

within the UK that will not adversely impact maritime services, indeed this has already 

been implemented in the case of mountain rescue services. 

However as an island with several inland navigable waterways (canals and rivers), for 

larger vessels there are not too many locations that are sufficiently remote from maritime 

activities to permit unqualified sharing with, for example, land mobile services. There is 

thus a need to develop a considered approach to possible sharing scenarios based on 

traffic demand. If these prove to be representative of wider trends in Europe they ideally 

would in addition need to be propagated internationally to achieve a harmonised 

approach, with the attendant advantages of larger product markets etc. 

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The introduction of 12.5 kHz channel spacing would considerably increase spectrum 

efficiency. It will of course not double frequency use, because it is on the one hand 

unrealistic to believe that the entire maritime VHF spectrum will be used on a 12.5 kHz 

basis and because on the other hand the reduction in the channel width with the ensuing 

reduction in frequency deviation will result in a degradation of the overall system 

performance. However, there will be a satisfactory net result in frequency efficiency. For 

additional information concerning a move from 25 kHz to 12.5 kHz channel spacing see 

section 6.12.7. 

The implementation of digital technology will result in a much better frequency efficiency, 

which cannot, however, be quantified at this point in time because the system 

characteristics are not yet known. 

6.8.10 Re-arranging the Frequency Spectrum of Appendix 18 to the Radio 

Regulations and Releasing Part of it for Other Applications 

The following concept for re-arranging the use of the Appendix 18 channels and using the 

remainder together with part of the frequencies available for VHF private maritime 

communications was considered by the Consultant based on the following assumptions: 

a) There is no need to maintain maritime VHF public correspondence channels 

due to the non-availability of commercial services and the availability in 

many coastal areas of alternative communication means (e.g. GSM). 

b) For a similar reason mirroring the situation with UK PBR licences, the need 

for private maritime VHF communications would decrease over time 

resulting in a reduced need to continue to provide as many frequencies as 

are now available for this purpose. 

c) There is increasing simplex and decreasing duplex use. 

d) The channel spacing is 12.5 kHz, thus doubling the number of available 

channels, with technical parameters as specified in Recommendation ITU-R 

M. 1084. 

e) The service requirements, except for public correspondence, of the current 

Appendix 18 are met. 

f) The re-arrangement does not prejudice a later transition to digital 

technology. 

g) Any implementation of the concept would require coordination with 

neighbouring countries. 

h) The use of split channels could be considered in accordance with ITU WRC- 

2000 revisions to Appendix 18. 

It may therefore have been feasible as an interim step prior to an all digital solution to 

take account of the demise of public correspondence and relocate users from the lower 

part of the international band to the upper part and at the same time implement 12.5 kHz 

spacing, initially in a block of channels between 156.075 and 156.275 MHz. The following 

bands would then have remained available for international maritime use as contained in 

Appendix 18 of the Radio Regulations, but without public correspondence: 

• Circa 156-156.9 MHz for DSC for distress, safety and calling, for inter-ship, for 

single- and two-frequency port operations and ship movement; 

• Circa 160.6-160.975 MHz inter-ship, single- and two-frequency port operations 

and ship movement paired with the band 156-156.9 MHz, as applicable, with a 

duplex spacing of 4.6 MHz; 

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• 161.975 and 162.025 ( formerly channels 87 and 88) maintained for AIS; 

• Reduction in the number of two-frequency channels for port operations and ship 

movement. 

The remainder of the current Appendix 18 frequencies together with part of the private 

maritime VHF band might then have been available for other applications, subject to the 

agreement of neighbouring administrations: 

• Circa 156.9-158.4 MHz paired with 161.5-163 MHz (excluding the AIS channels 

161.975 and 162.025 MHz) subject to additional rationalisation to take account of 

other use within the United Kingdom of certain frequencies within these bands. 

After studying in detail licensing statistics and channel availability a number of issues 

have become apparent: 

• Whilst the sub-band 156.075 -156.275 MHz and its 4.6 MHz pair remain 

relatively clear, public correspondence channels in the lower part of the 

international band have already been assigned to other users. 

• The private CSR band adjacent to the international band is additionally used for 

other services within the UK, possibly message handling which would need to be 

addressed in proposing major changes. 

• Public correspondence undoubtedly remains a requirement for ships and small 

boats. If future generations of terrestrial mobile services offer reduced coverage 

of European waters the demand is likely to increase. This question requires 

much more study at the European level before relinquishing all the current 

internationally assigned spectrum resource. 

The Consultant is still of the opinion that a major rationalisation of VHF maritime spectrum 

is warranted but this is not a simple task and requires an in-depth study and public 

consultation to determine the correct course of action. 

6.8.11 Socio-economic Issues 

If any UK specific solution is implemented in the VHF maritime bands it must be 

remembered particularly that coast station equipment is only required in small quantities, 

economies of scale cannot be achieved, irrespective of whether conventional or more 

advanced technology is used. 

From the economic point of view, the implementation of an interim system with 12.5 kHz 

channel spacing complementary to the present system with 25 kHz channel spacing, 

which has to be maintained due to the international character of VHF maritime radio and 

in particular to meet the requirements of the GMDSS, might not be desirable. It could 

place an unnecessary financial burden on the shipping industry, which would have to 

change equipment again, once a final digital solution was finally introduced. It should, 

however, be borne in mind, that such a radical change in the maritime mobile service will 

take a lot of time to achieve, since developing countries in particular will require a very 

long transition time to implement the new system. 

In order to obtain a feel for the cost and numbers involved in a change which would 

require new equipment licensing statistics were taken from the last Annual Report and 

Accounts of the Radiocommunications Agency, Table 6-6. This indicates that numbers of 

CSR licences are reasonably static but ship station licences have grown at a rate of about 

10% in the last year. Not all CSR licences are for a single base station so some care is 

needed in interpreting these figures but let us assume that around 65,000 equipments 

could be involved in any changes. The figures also suggest that there were 3625 

assignments in 2003 and some 3665 assignments in 2002. 

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Licence Numbers 

YEAR 2003 2002 

Coastal Station Radio: 

CSR (UK) 507 558 

CSR (Marina) 431 442 

CSR (International) 492 464 

CSR Training Establishment 20 2 

Coastal Station Radio subtotal 1,450 1,466 

Ship Radio (including Ship Portable 

Radio): 

Charities 436 332 

Others 62,046 58,618 

Ship Radio subtotal 62,482 58,950 

Table 6-6 2002 and 2003 UK CSR Licensing Statistics 

The implementation of digital technology requires a completely new generation of 

equipment not compatible with the present system. This will have serious economic 

implications for the shipping industry and will be a reason for developing countries to 

delay the process. On the other hand, this will give industry the chance to develop and 

place on the market a new generation of equipment. Furthermore, the similarity in 

technology with land-mobile equipment will make it possible for the maritime community 

to benefit from economies of scale, although the number of production units will be far 

less than in the land-mobile service. 

A standard VHF marine radio would cost in the order of £200, one that requires specialist 

filters and a modified synthesiser for a total market size of 65,000 is likely to be £500 – 

£700. Digital radio prices have been discussed with Nokia, a typical TETRA mobile 

terminal would be of the order of £850 but this assumes a terminal made to a common 

European standard. For example a TETRA like terminal made for APCO, the US public 

safety market would be of the order of £3000. A coast station equipment would be 

significantly more expensive. From this order of figures it seems clear that a harmonised 

European approach is needed to push volumes up and achieve the necessary economies 

of scale. 

6.9 VHF – Communications (Private) 

Many countries have in the past recognised the need for additional maritime channels 

either for company business or for co-ordinating leisure or sporting activities. 

Furthermore, within the past 20 years there have been various ideas in Europe and 

elsewhere concerning the identification of frequency bands for an automatic maritime 

public telephone system. An example of a working system can be found in the United 

States. 

The US Automated Maritime Telecommunication System (AMTS) is described by the 

FCC as a specialised system of coast stations providing integrated and interconnected 

marine voice and data communications, somewhat like a cellular phone system for tugs, 

barges and other vessels on waterways. AMTS is available in US coastal waters and 

inland waterways and uses spectrum in the range 217 – 220 MHz. 

Page 230

Closer to home the CEPT consultative process of Detailed Spectrum Investigations (DSI) 

in its 2 nd phase report published in March 1995 recommended that consideration be given 

to a harmonised European private maritime band 157.45 – 157.95 MHz paired with 

162.05 – 162.55 MHz using 5 or 6.25 kHz channel spacing. In Europe, as mentioned 

elsewhere in this Chapter the commercial success of GSM with its extensive coverage of 

coastal and inland waterways has undermined the commercial viability for any dedicated 

maritime public correspondence system but there will continue to be a requirement for a 

limited number of conventional private ship to shore communication channels. 

Some countries are already using frequencies adjacent to those of Appendix 18 to the 

Radio Regulations for private VHF maritime communications. In the United Kingdom the 

following non exclusive (for maritime) bands are available for this purpose: 

• 157.45-158.5 MHz; 

• 160.975-161.475 MHz; 

• 162.05-163.00 MHz. 

Where two frequency simplex or duplex operation is employed on designated frequencies 

the spacing between transmitter and receiver frequencies is 4.6 MHz. 

The technical characteristics are identical to those for international VHF maritime 

communications on Appendix 18 channels. They are specified in Recommendation ITU-R 

M.489. Since this is a purely national matter, administrations are free to take any 

measures they see fit. However, due to alternative short range communication means, in 

particular GSM, it is believed that there is no real need to continue to provide as many 

frequencies as are now available for private maritime VHF communications. A detailed 

proposal for an alternative use in connection with part of the Appendix 18 frequencies 

was considered in Section 6.8. 

The land-based and shipborne equipment have to comply with the R&TTE Directive. 

Since the band in question is not used for distress and safety communications, there is no 

requirement emanating from the SOLAS Convention. 

6.10 VHF - AIS (Automatic Identification System) 


Two international channels have been allocated for AIS use, i.e. AIS 1: 161.975 MHz and 

AIS 2: 162.025 MHz (see Appendix 18 to the Radio Regulations, Table of transmitting 

frequencies in the VHF maritime mobile band). These channels were formerly coast 

station transmit frequencies of channels 87 and 88. They will be used for an automatic 

ship identification and surveillance system capable of providing worldwide operation on 

high seas, unless other frequencies are designated on a regional basis for this purpose. 

The frequencies are simplex frequencies for ship and coast station use. 


Automatic Identification System (AIS) is a broadcast system, operating in the VHF 

maritime mobile band. It is capable of sending and receiving ship information such as 

identification, position, course, speed and more, to and from other ships and to and from 

shore. The AIS therefore allows an efficient exchange of navigational data between ships 

and between ships and shore stations, thereby improving the safety of navigation. The 

system is used primarily for surveillance and safety of navigation purposes in ship-to-ship 

use, ship reporting and vessel traffic service applications. It can also be used for other 

maritime safety related communications. The system is autonomous, automatic and 

continuous and operates primarily in a broadcast mode, but also assigned and 

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interrogation modes using TDMA techniques. The system is capable of expansion to 

accommodate future expansion in the number of users and diversification of applications, 

including vessels which are not subject to IMO AIS carriage requirements, aids to 

navigation and search and rescue. 

With the capabilities of ship-to-ship, ship-to-shore and shore-to-ship communications, AIS 

will greatly enhance the safety, improve the efficiency of the traffic management and 

increase the vessel security and emergency response capabilities. Specifically, the 

potential benefits of AIS include providing a more efficient vessel traffic management as a 

result of knowing accurate location and speed of the vessels, monitoring vessel speeds 

especially for hazardous cargo and deeper draft vessels in narrow and shallow waters 

and faster response time to vessels in case of security concerns and vessel accidents or 

incidents. The potential benefits to users include the reduction of overall transit time as a 

result of better scheduling and the timely dispatching of pilots etc. 

Figure 6-4: Diagram – Kongsberg Maritime System 

As indicated in the above diagram AIS can be used on buoys, lighthouses and lightships. 

The system uses a self-organised TDMA (SOTDMA 27 ) system with fixed access 

(FATDMA) used at base stations and accommodates all users and meets the likely future 

requirements for an efficient use of the spectrum. The ship station and base station uses 

either 25 or 12.5 kHz single frequency simplex channels. The GMSK coded data 

frequency modulates the transmitter; the bit rate is 9600 bit/s independent of the channel 

width. 

27 By convention, “SODTMA” is used in the Maritime community for self-organising TDMA 

whereas “STDMA” is used by the Aeronautical community 

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The operational characteristics of the universal AIS using TDMA techniques in the VHF 

maritime band are specified in Recommendation ITU-R M.1371. Class A shipborne 

equipment has to comply with relevant IMO AIS carriage requirements. Class B shipborne 

equipment will provide facilities not necessarily in full accordance with IMO AIS carriage 

requirements. 


The coast station has to comply with the R&TTE Directive. Class A ship-borne equipment 

has to comply with relevant IMO AIS carriage requirement as amended by the Maritime 

Safety Committee MSC 73 and MSC 76 (see Annex 6). Class B ship-borne equipment will 

provide facilities not necessarily in full accordance with IMO AIS carriage requirements. 

In this section it may be pertinent to note that the question of IPR has been raised with 

respect to the use of the Self-Organised Time Division Multiple Access (STDMA) 

technique, also called VDL (VHF Digital Link) Mode 4. STDMA is a technology that can 

potentially be used for providing an air/ground and/or an air/air datalink, as well as 

navigation and surveillance capabilities. 

During the standardisation process of VDL Mode 4/STDMA within ICAO (International 

Civil Aviation Organisation) and IMO (International Maritime Organisation), questions 

have been posed to the European Commission concerning how to handle potential 

intellectual property rights related to technologies that are subject to international 

standardisation within UN specialised agencies. 

Despite various concerns the European Commission is of the opinion that the intellectual 

property rights holders concerned are prepared to offer fair, reasonable and nondiscriminatory 

monetary and non-monetary terms for the licence to use any IPR and 

therefore the information provided on the patents could not be considered as insufficient 

to cover the needs of a standardisation body such as ICAO or IMO. Nevertheless if IPR 

issues remain difficulty vessels using AIS may have to use Carrier Sense Multiple Access 

(CSMA) in the future. 


The technology used has only been recently developed and implemented. Therefore for 

the time being improvements are neither required nor available. 

6.10.6 Allocation Sharing Issues 

As mentioned in section 6.8.10 the two AIS frequencies might eventually fall within a band 

proposed for land mobile exploitation. If this proves to be the case the UK might lobby 

within CEPT and the ITU for replacement or additional AIS frequencies which fall within 

the eventual band allocated in the UK to the maritime mobile service. 


The reduction of the channel spacing in the maritime mobile VHF band from 25 kHz to 

12.5 kHz would make the system more spectrally efficient (see also sections 6.8.9 and 

6.12.7). This would not affect the signal bit rate. 

Recommendation 6.7: It is recommended that an in depth study of all UK 

applications within the bands 156.0 – 158.5 MHz and 160.6 – 163.1 MHz ( including 

Appendix 18 (to the Radio Regulations) international maritime channels as well as Coast 

Station Radio private UK maritime channels) should be considered. The goal would be to 

determine: 

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� The future VHF spectrum requirements of the UK maritime industry with a view to 

rationalisation of the current spectrum taking account recent changes in the 

industry and the introduction of new technologies. 

� The study should further ascertain current and future maritime public 

correspondence needs and ascertain whether a combination of GSM/IMT-2000 

and satellite communications is likely to satisfy communications requirements in 

British waters. 

� Such a study would need to take account of the need to: 

o Ensure 25 kHz fitted ships would be able to operate as intended for an 

agreed period; 

o Ensure 161.975 and 162.025 MHz are maintained for AIS; 

o Seek to achieve a reduction in the number of two-frequency channels for 

port operations and ship movement. 

6.11 EPIRBs (121.5 MHz / 243 MHz / 406.1 MHz) 


Frequency used: 121.5 MHz; see Appendix 15 to the Radio Regulations specifying 

frequencies for distress and safety communications for the Global Maritime Distress and 

Safety System (GMDSS). 121.5 MHz is also the emergency frequency for civil aviation 

and is also used for search and rescue operations to and from aircraft. EPIRBs also 

generally transmit on the survival craft emergency frequency of 243 MHz. There is also a 

provision for DSC EPIRBs on 156.525 MHz (channel 70). VHF EPIRBs are part of the 

GMDSS. 

COSPAS-SARSAT satellites detect EPIRBs/ELTs transmitting on the specific radio 

frequencies of 121.5 MHz, 243 MHz and 406.0 to 406.1 MHz. A satellite detecting an 

active EPIRB/ELT on these frequencies needs to have both the EPIRB/ELT and a ground 

station in its visibility window in order that an alert can be received. This is known as 

'Local Mode' where only ground stations in the field of view of the satellite detecting an 

EPIRB/ELT will receive the alert data. 


An emergency position-indicating radio beacon (EPIRB) is a station in the mobile service 

the emissions of which are intended to facilitate search and rescue operations (see RR 

No. 1.93). Since these beacons communicate with the aeronautical VHF service, the 

transmitted signals are double-sideband amplitude modulated (full carrier). The 

modulation consists of a characteristic audio-frequency signal obtained by amplitude 

modulation of the carrier frequency with a downward audio-frequency sweep within a 

range of not less than 700 Hz between 1600 Hz and 300 Hz. The technical characteristics 

of EPIRBs on 121.5 MHz and 243 MHz are specified in Recommendation ITU-R M.690. 


The aeronautical emergency frequency 121.5 MHz is used for the purposes of distress 

and urgency for radiotelephony by stations of the aeronautical mobile service using 

frequencies in the band between 117.975 MHz and 137 MHz. This frequency may also be 

used for these purposes by survival craft stations. Emergency position-indicating radio 

beacons use the frequency 121.5 MHz in accordance with Recommendation ITU- 

R M.690-1. Mobile stations of the maritime mobile service may communicate with stations 

of the aeronautical mobile service on the aeronautical emergency frequency 121.5 MHz 

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for the purposes of distress and urgency only, and on the aeronautical auxiliary frequency 

123.1 MHz for coordinated search and rescue operations, using class A3E emissions for 

both frequencies (see also RR 5.200). They shall then comply with any special 

arrangement between governments concerned by which the aeronautical mobile service 

is regulated 


The EPIRB has to comply with the Marine Equipment Directive; compliance with this 

Directive guarantees automatically compliance with the relevant requirements in the 

SOLAS Convention. It shall also comply with the standards and recommended practices 

of ICAO, in this case Annex 10, Volume III, Part II, Chapter 5. 

6.12 UHF – On Board Communications 

6.12.1 Frequency Allocations (international and national) 

In the maritime mobile service, the frequencies 457.525 MHz, 457.550 MHz, 457.575 

MHz, 467.525 MHz, 467.550 MHz and 467.575 MHz may be used by on-board 

communication stations. Where needed, equipment designed for 12.5 kHz channel 

spacing using also the additional frequencies 457.5375 MHz, 457.5625 MHz, 467.5375 

MHz and 467.5625 MHz may be introduced for on-board communications. The United 

Kingdom has permitted the use of these additional four channels. The use of these 

frequencies in territorial waters may be subject to the national regulations of the 

administration concerned (RR No. 5.287). WRC-97 adopted the introduction of a channel 

spacing of 12.5 kHz for maritime UHF on-board communications, to be used on a 

voluntary basis. 

The bands 456-459 MHz and 460-470 MHz are allocated world-wide to the fixed and 

mobile services on a primary basis. 

It should be noted that the frequencies 156.750 and 156.850 MHz (Appendix 18 to the 

Radio Regulations, channels 15 and 17) are also available for on-board communications 

subject to certain restrictions e.g. terminal power output. 

On a national basis, other frequencies can be used, subject to successful coordination, if 

so required. It is also likely that within Europe, licence exempt PMR446 equipment is also 

used for on-board applications as well as on land. 


On-board communications are voice communications and cover a wide range of 

communication needs, such as internal communications on board one ship, with other 

ships nearby and between one ship and its personnel on land, e.g. for mooring 

operations. Low-power, hand-held equipment with frequency or phase modulation is 

used. The characteristics of on-board equipment are specified in Recommendation ITU-R 

M.1174 (incorporated by reference in the Radio Regulations). The UK is seeking 

amendments to this recommendation in order to permit all types of data signals to be 

transmitted. 


On-board communications are not part of the GMDSS. 


On-board equipment has to comply with the R&TTE Directive. 

Page 235


The use of 25 kHz equipment with a maximum deviation of 16 kHz is not compatible with 

12.5 kHz equipment working on the four interleaved channels. In order to minimise 

possible interference, use of 12.5 kHz technology on all ten channels is encouraged. This 

will not eliminate interference altogether, because there may be on-board 

communications by ships under foreign flags with 25 kHz technology in the same harbour 

area as new equipment, but it will significantly reduce the probability of interference. 

Consider e.g. the Cowes yachting regatta with a great need for on-board 

communications. Simultaneous use of 25 kHz and 12.5 kHz equipment will create 

interference both ways; into the 25 kHz receiver from the interleaved 12.5 kHz channel 

and into the 12.5 kHz receiver from the 25 kHz transmitter with a maximum deviation of 

16 kHz spilling over into the interleaved 12.5 kHz channel. 


In the medium to long run, implementation of digital techniques is possible and desirable. 

There may also be a need for data communications in addition to voice. Some of the 

channels indicated in Section 6.12.1 could be identified for digital on-board 

communications. ITU-R should be invited to study the matter. 


The use of 12.5 kHz channels and the implementation of digital techniques will improve 

spectrum efficiency. However in the case of interleaving FM channels there is an issue of 

reduced deviation and therefore reduced coverage. Studies conducted in the UK in the 

late 1960s concerning the implementation of a VHF radiotelephone service concluded 

that in theory a 12.5 kHz mobile receiver would require between 6.2 and 13 dB more 

signal than a 25 kHz mobile for a comparative edge of service performance in an urban 

environment. However low power systems such as on board systems generally have a 

reduced dynamic range of signals and this is favourable to the narrower channel spacing 

condition. Against this there is a small deterioration in signal to noise ratios at 12.5 kHz 

spacing due to the reduced deviation. This occurs chiefly in the good signal areas and 

amounts to 2.5 – 3 dB. This is true at VHF and UHF. 

UHF PBR field trials were conducted in London in 1969. The results of test and 

observations made by ITT over a 12 month period (later confirmed by the Ministry of 

Posts and Telecommunications (MPT) in 1973) show that coverage at 12.5 kHz is 

virtually indistinguishable from the coverage obtained from a 25 kHz system. In terms of 

absolute range, impulsive interference, and speech quality the difference between the two 

systems was barely perceptible subjectively. 

It may be appropriate to conduct some subjective tests in the marine environment to 

confirm the results of previous decades. 

Recommendation 6.8: Use of 12.5 kHz technology on all ten UHF on-board 

channels is recommended in order to minimise possible interference. 

6.12.8 Socio economic factors 

On-board equipment is generally low-cost; its replacement by new digital equipment 

should not cause major economic problems. Should digital technology be implemented, 

dual-mode equipment would be required for a transition period to permit communication 

within and between ships that still use analogue techniques. It is assumed that the 11,000 

or so SOLAS vessels in the red ensign fleet would have at least two UHF hand portable 

transceivers on board, thus at approximately £200 per equipment the cost of replacement 

of 25 kHz radios by new radios fitted with 12.5 kHz filters would be of the order of £6 

Page 236

million . A digital or dual mode alternative, especially if the market size is small, could be 

2 to 4 times larger. 

6.13 UHF Communications (GSM and IMT-2000) 

The GSM system around 900 MHz and to a lesser degree GSM 1800 operating at 1.8 

GHz are increasingly used by the maritime community as a substitute for maritime VHF 

public correspondence. This together with the increasing use of satellite personal 

communications systems has contributed to the closure of all maritime VHF coast stations 

previously open for public correspondence in the United Kingdom. This is likewise true for 

other European countries. The advantage of GSM is obvious; it offers a high-quality 

automatic service available in coastal in-shore areas as well as on land, whereas the 

setting-up of a maritime VHF public correspondence call is a cumbersome manual 

process via the coast station. Since 900 MHz GSM is somewhat higher than conventional 

VHF maritime frequencies, GSM coverage in coastal waters is rather less than maritime 

VHF channels. 

IMT-2000 is now being implemented and may eventually replace GSM 900 and GSM 

1800. In order to maintain the present attractiveness of GSM for the maritime community, 

it would help maritime areas (similarly to rural areas) if the IMT-2000 system were to be 

engineered to also operate in the 900 MHz band as well as in its current 2 GHz and 

eventually 2.5 GHz expanded allocation. 

As well as providing service in European coastal waters such a development would also 

provide a cost effective means of providing GSM service in rural land areas. 

From the allocation point of view the 900 MHz band is also available for IMT-2000. Radio 

Regulation No. 5.317A stipulates that administrations wishing to implement IMT-2000 

may use those parts of the band 806-960 MHz which are allocated to the mobile service 

on a primary basis and are used or planned to be used for mobile systems. 

Resolution 224 (WRC-2000) on frequency bands for the terrestrial component of IMT- 

2000 below 1 GHz requests administrations which are implementing or planning to 

implement IMT-2000, to consider the use of bands below 1 GHz and the possibility of 

evolution of first- and second-generation mobile systems to IMT-2000, in the frequency 

band identified in No. 5.317A, based on market demand and other national 

considerations. An important consideration is the requirement to provide coverage in 

coastal waters for the benefit of the maritime community. 

GSM equipment and also IMT-2000 equipment is extremely low in cost and therefore also 

extremely attractive for the maritime community as opposed to specialised maritime 

equipment where due to the rather small number of units produced economies of scale 

can only be achieved in a very limited manner. 

The equipment shall comply with the R&TTE Directive. 

Recommendation 6.9: The GSM system at 900 MHz is increasingly used by the 

maritime community as a substitute for maritime VHF public correspondence. IMT-2000 is 

now being implemented. In the long term, it will likely replace GSM 900. In order to 

maintain the obvious advantages of public mobile telecommunication systems for the 

maritime community, it will be of particular importance that IMT-2000 in coastal areas 

should be available in the 900 MHz band. This is because the 2 GHz band, whilst 

particularly suited for areas on land with high traffic densities and thus small cells, will 

have an off shore range that is inadequate for serving the maritime community effectively. 

It is therefore recommended that frequencies at 900 MHz should be made available for 

the implementation of IMT-2000 in coastal areas, when GSM is planned for 

decommission. 

Page 237

6.14 Maritime Satellite Communications in the 1.5/1.6 GHz Band 

and above 


The following bands are available for maritime satellite communications: 

• 1525-1559 MHz (space-to-Earth); 

• 1626.5-1660.5 MHz (Earth-to-space). 

Note: Only those bands are indicated, where a service is provided by Inmarsat. There are 

other bands available in principle due to their allocation status. 

Usage of the bands indicated above for the GMDSS is as follows (see Appendix 15 to the 

Radio Regulations): 

• In addition to its availability for routine non-safety purposes, the bands 1530- 

1544 MHz and 1 626.5-1 645.5 MHz are used for distress and safety purposes. 

GMDSS distress, urgency and safety communications have priority in these 

bands. 

• Use of the band 1544-1545 MHz is limited to distress and safety operations, 

including feeder links of satellites needed to relay the emissions of satellite 

emergency position-indicating radio beacons to earth stations and narrow-band 

(space-to-Earth) links from space stations to mobile stations. 

• Use of the band 1 645.5-1 646.5 MHz is limited to distress and safety operations, 

including transmissions from satellite EPIRBs and the relay of distress alerts 

received by satellites in low polar Earth orbits to geostationary satellites. This 

relates to No. 5.375 of the Radio regulations where the use of the band 1 645.5- 

1 646.5 MHz by the mobile-satellite service (Earth-to-space) and for inter-satellite 

links is limited to distress and safety communications 


The Inmarsat system is a geostationary satellite system. It offers a wide range of 

communication facilities: 

• Inmarsat A: telephony, fax and data system based on analogue technology, 

more than 20 years old; the Inmarsat A service will be closed down at the end of 

2007; 

• Inmarsat B: digital successor to Inmarsat A, direct dial, high quality telephony, 

telex, fax and data system, 9.6 to 64 kbit/s; 

• Inmarsat C: low cost store-and-forward data messaging terminals for small ships, 

also for the GMDSS; 

• Inmarsat E: GMDSS EPIRB. 


Maritime satellite communications serve the global communication needs of the maritime 

community, in particular in the public correspondence area. They have to a large extent 

replaced HF maritime public correspondence. They also form an essential part of the 

GMDSS. The service is provided by Inmarsat Ltd, a commercial company registered in 

the United Kingdom. Inmarsat has a quasi-monopoly in the field of maritime satellite 


Page 238

Inmarsat was the world’s first global mobile satellite communications operator and is still 

the only one to offer a mature range of modern communications services to maritime, 

land mobile and aeronautical users. Formed as a maritime-focused intergovernmental 

organisation over 20 years ago, it has been a commercial company since 1999. The 

public service duties, i.e. the GMDSS function for the maritime community, and air traffic 

control communications for the aeronautical community, are supervised by a small 

intergovernmental organisation. 


Coast station equipment for general and for distress and safety use has to comply with 

the R&TTE Directive. 

Recommendation ITU-R M.830 contains operational procedures for mobile-satellite 

networks or systems in the bands 1530-1544 MHz and 1626.5-1645.5 MHz which are 

used for distress and safety purposes as specified for GMDSS. 

6.14.5 Possible Improvements to Existing Technology, Possible New 

Technology (in-band) 

Due to the international character of the service, the quasi-monopoly of Inmarsat and the 

high cost involved in developing a competitive system there is no room for any national 

improvement of the existing technology or the implementation of new technology. 

6.14.6 The ESV issue 

Resolution 82 of ITU WRC 2000 resolved to invite the ITU-R to continue to study, as a 

matter of urgency, the regulatory, technical and operational constraints to be applied to 

Earth Stations on Vessels (ESV) operating in the fixed satellite service (FSS); in particular 

to determine the appropriate value for the minimum distance from ESV stations beyond 

which these stations can be assumed not to have the potential to cause unacceptable 

interference to stations of other services of any administration and beyond which no 

coordination would be required 

A licensing regime for ESVs on board vessels has the potential to provide valuable 

services to ships and their passengers and crew, and licensing them, subject to rules for 

protecting terrestrial systems from interference in shared bands would enable operators 

to make more efficient use of their spectrum. Crews and passengers have come to expect 

a similar full range of voice, video, and data communications that they enjoy on land 

whilst travelling. With their broad footprints the FSS is well-suited to satisfying these 

requirements. In some cases mobile satellites are best equipped to satisfy maritime 

communications needs, however, in other instances, the services offered on a fixed 

satellite system may be the preferred choice. Mobile satellites and fixed satellites have 

different system architectures, coverage patterns, link budgets, service capabilities, and 

price structures. To maximize efficiency, enhance flexibility, increase competition, and 

improve service options, a regulatory regime could be developed that makes it possible 

for the maritime industry to transmit and receive through both types of satellite systems, 

and leave it to the consumer to determine which type of system is optimal for particular 

service needs. 

The regulatory and operational provisions for ESVs transmitting in the 5 925-6 425 MHz 

and 14-14.5 GHz bands were determined at ITU WRC-03. It is the responsibility of the 

administration that issues the licence for the use of ESVs in these bands to ensure that 

such stations do not present any potential to cause unacceptable interference to the 

services of other concerned administrations. The minimum distance from a coast line 

where ESVs can operate without the prior agreement of any administration are 300 km in 

the 5 925-6 425 MHz band and 125 km in the 14-14.5 GHz band. 

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6.15 Maritime Communications Spectral Efficiency 

Development Impact on Spectrum Comment 

LF Communications 

LF DGPS Available for other services in 

medium to long term 

MF Communications 

Digital introduction and decreased 

use 

HF Communications 

Digital introduction and decreased 

use 

VHF Communications 

12.5 kHz channelling or digital 

introduction. 

UHF Communications 

On board maritime 

Introduce 12.5 kHz channelling on 

all 10 channels 

MF Spectrum may be freed in the 

long term. 

Premature to consider HF spectrum 

decrease. 

More efficient use of existing 

spectrum 

Eventually spectrum efficiency 

improved by around 40% taking 

account of reduced range 

Introduction of SRDs Very little if ISM bands used. More 

impact if regional solutions used. 

IMT-2000 at 2 GHz Possible reduction in coverage of 

coastal waters compared with 

GSM900 

Review desirable. 

Consideration for use by 

broadcasting. Dependent on 

DGNSS 

Review of 415 – 526.5 kHz 

desirable. Non-civil 

requirements in HF spectrum. 

Consideration of adaptive 

digital techniques. NVIS 

propagation. 

Digital Email services and 

adaptive techniques. NVIS 

propagation in low HF. 

Consider a reduction in 

maritime spectrum 

Problems may occur in interim 

period 

Consider introduction of IMT- 

2000 at 900 MHz. 

Table 6-7 Maritime Communications Spectral Efficiency 

6.16 The Global Maritime Distress and Safety System (GMDSS) 

and the International Convention for the Safety of Life at 

Sea (SOLAS Convention) 

The GMDSS is an internationally recognised distress and safety radiocommunication 

system for ships replacing the previous safety system which relied on Morse telegraphy 

on 500 kHz and on radiotelephony on 2182 kHz and on VHF channel 16 (156.8 MHz). 

The GMDSS is an automated ship-shore-system using digital selective calling on 

terrestrial frequencies as well as satellites. The GMDSS is mandated for ships 

internationally by the SOLAS Convention, an international treaty concluded by the 

member states of the International Maritime Organisation, a United Nations specialised 

agency, and was instrumental in the development of the GMDSS. The procedures 

governing the use are contained in the ITU Radio Regulations and in ITU-R 

Recommendations. The GMDSS became operational on 1 st February 1999. 

The relevant provisions of the SOLAS Convention apply to cargo ships of 300 gross tons 

and over when travelling on international voyages or in the open sea and to all passenger 

ships carrying more than twelve passengers when travelling on international voyages or 

in the open sea. It is also applicable to various classes of fishing vessels. The specific 

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carriage requirements for distress and safety radiocommunication equipment depend on 

the sea area (A1 to A4) in which the ship is sailing. 

Under the SOLAS Convention, every ship, while at sea, must have the facilities for 

essential communications, namely: 

• transmitting ship-to-shore distress by at least two separate and independent 

means; 

• receiving shore-to-ship distress alerts; 

• transmitting and receiving ship-to-shore distress alerts; 

• transmitting and receiving search and rescue co-ordinating communications; 

• transmitting and receiving on-scene communications; 

• transmitting and, as required, receiving signals for locating; 

• transmitting and receiving maritime safety information; 

• transmitting and receiving general radiocommunications to and from shore-based 

radio systems or networks; 

• transmitting and receiving bridge-to-bridge communications. 

6.17 Compliance of Maritime Equipment with EU Directives 

6.17.1 Marine Equipment Directive 

The SOLAS Convention requires that large passenger and large cargo ships carry 

specific equipment for distress and safety purposes. 

The European Union has adopted the Marine Equipment Directive (96/98/EC, amended 

by 98/85/EC, 2001/53/EC and 2002/75/EC) in order to ensure application of obligations 

under the SOLAS Convention in the EU member states. The Directive applies to all safety 

and distress equipment installed on ships which are subject to IMO carriage requirements 

under the SOLAS Convention. The MCA has indicated that any radio, radar or navigation 

equipment approved under the Marine Equipment Directive has been entirely acceptable 

for use on all UK vessels since 1 January 1999 and will continue to be acceptable for the 

foreseeable future. The Directive does not apply to distress and safety equipment at coast 

stations. 

The Marine Equipment Directive requires that the compliance of equipment with the 

requirements of international conventions shall be demonstrated solely in accordance 

with the testing standards and conformity procedures referred to in the Directive. In some 

cases, the Directive refers to IEC and ETSI standards, in which case the manufacturer 

may choose which standard to apply. 

Directive 96/98/EC is implemented in the UK by the Merchant Shipping (Marine 

Equipment) Regulations 1999. As the equipment does not fall within the scope of the 

R&TTE Directive but must meet the requirements of the Marine Equipment Directive, 

equipment shall bear the "ship's wheel" marking rather than the CE marking. 

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6.18 R&TTE Directive 

Maritime radio equipment which is not covered by the SOLAS Convention is covered by 

the Radio and Telecommunications Terminal Equipment Directive (R&TTE Directive) 

Directive 99/5/EC. This is a “New Approach Directive”. It relies on harmonised standards 

developed by recognised European standards bodies, e.g. ETSI, to define technical 

characteristics which can be used to meet the essential requirements in accordance with 

the Directive. The Directive also applies to receivers (see Article 2(c) of the Directive). 

See also section 4.4. 

The Directive applies to equipment not covered by the Marine Equipment Directive, i.e. 

also for coast station equipment used for safety and distress purposes. 

From a UK standpoint the UK Radio Interface Requirements are also pertinent. Under the 

Radio Equipment and Telecommunications Terminal Equipment Regulations 2000, which 

implements the R&TTE Directive in the UK, it is a legal requirement that all radio 

equipment (with certain specific exceptions) meets the essential requirements of the 

Directive. It is the responsibility of any person who places radio equipment on the market 

or takes it into service in the UK to ensure that the requirements of the R&TTE Directive 

are met. It must be marked with the CE marking which means that a written declaration of 

conformity by the manufacturer has been drawn up for it, together with information for the 

user on the intended use of the equipment (e.g. Maritime radio). 

6.19 Conclusions 

The radio frequency spectrum is a finite and extremely valuable resource. It is therefore 

important that the commercial and social benefit that can be derived from it is maximised. 

The maritime mobile service is primarily an international service. The international 

character requires the harmonisation of frequencies, of equipment characteristics and 

operational procedures in order to guarantee the smooth interoperability of stations of 

different countries that are all using the same portion of the spectrum. The service is 

governed by international agreements, such as the Radio Regulations and the 

Convention for the Safety of Life at Sea (SOLAS Convention) and also by relevant ITU-R 

Recommendations. It is therefore only to a limited degree open to diverging national 

solutions. Thus, there is only very limited room for the implementation of more spectrally 

efficient radiocommunication techniques and technology. Possibilities do certainly exist in 

frequency bands, that deliver smaller coverage, inter alia higher bands, such as VHF, or 

where usage is rapidly decreasing (HF) due to alternative means of long-distance 

communications. On a world-wide level, changes in technology can only be implemented 

in the medium-to-long term, because developing countries in particular are very reluctant 

to agree to changes due to the high cost involved to replace existing technology. 

Professor Martin Cave in his 2002 ‘Review of Radio Spectrum Management’ in the United 

Kingdom recommended that the Government should, wherever technically and 

operationally feasible, facilitate greater flexibility in the use of a given frequency band. 

This recommendation is generally pertinent since if by a combination of regulatory and 

technical processes it is possible to improve spectrum efficiency in any frequency band, 

congestion may be alleviated, more users accommodated or spectrum could be 

transferred to other users or alternative applications. However, in view of the fore-going, 

there is not much flexibility for an administration to deviate from the rules agreed 

internationally. This has to be taken into account when considering possibilities to 

increase the efficiency of frequency usage. 

To a certain extent the industry focus for peripheral equipment is still directed towards the 

U.S. and this gives their indigenous industry a great advantage. All industries favour large 

markets and the attendant economies of scale. The downturn in maritime trade, flags of 

convenience and the more diverse nature of ship building has tended to disperse the 

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suppliers of radiocommunications equipment. Scandinavia, the United Kingdom, Japan 

and the U.S. have all contributed significantly to the manufacture and supply of maritime 

electronics. 

But whilst it may be possible to develop systems technically market issues are also 

important. Most equipment manufacturers will be looking for markets for their products on 

a global basis, a regional approach for a sophisticated and innovative spectrum usage 

philosophy may fail because of the absence of economies of scale in the provision of 

equipment. It will therefore be necessary to examine how to increase the market 

possibilities for any approach taken. 

It is against such socio-economic issues that the feasibility of introducing more spectrally 

efficient technologies must be considered. It will also be necessary to gauge the 

possibility and likelihood of whether significant changes to the status-quo are likely to 

occur within the various regional and international organisations. 

A number of recommendations have been developed from the considerations discussed 

in Chapter 6. Where there is no recommendation for a given frequency band or 

application, the status quo should be maintained for the reasons given in the relevant 

sections. In general the recommendations suggest a policy. 

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7 Licensing 28 

7.1 General 

The purpose of this Chapter was to examine the various elements taken into account by a 

number of prominent aeronautical and maritime nations including EU Member States, in 

developing licensing regimes and setting fees and charges for land based and mobile 

aeronautical and maritime radiodetermination and radiocommunication systems. The 

actual levels of fees and charges were also analysed and compared, on a country by 

country basis. 

The wide disparity between countries in the approaches to setting fees and charges for 

use of radio spectrum also makes comparison difficult. For example, some countries have 

adopted administrative pricing methods 29 in an attempt to encourage more efficient use of 

the spectrum, whereas others adopt a cost recovery approach or apply market based 

methods, such as auctions, for large spectrum assignments. 

A key objective of this task was to determine transparency of national licensing regimes 

and to clarify the justification for administrative fees and spectrum fees / charges. As part 

of the work, it was intended that comparisons would be made between the various 

approaches used by administrations to determine fees and charges, and consideration 

given to possible approaches to good practice by European NRAs in terms of meeting the 

objectives of the Licensing Directive 30 . The Licensing Directive is not part of the current 

European regulatory framework but for reasons explained below its terminology has been 

used in this document. Reference should be made to section 7.2.1.1 for details 

concerning the European telecommunications regulatory framework in operation today. 

For the purpose of considering licensing and fees and charges regimes around the World, 

and in line with the former European terminology within the framework of the Licensing 

Directive, Administrative Fees and Spectrum Charges have been defined as follows: 

Administrative Fees are fees intended to cover the costs of examining an application for a 

licence, granting the relevant authorisation and verifying compliance with the terms and 

conditions set once the service or network is operational. Under the terms of the 

Licensing Directive (Article 11.1), Member States were required to ensure that such fees 

sought only to cover the administrative costs incurred in the issue, management, control 

and enforcement of the applicable individual licences. In the case of General 

28 Where an administrative or regulatory term is mentioned in association with a particular 

country, the use of the word or term will assume the definition or meaning applicable in 

the country concerned (e.g. apparatus licence tax in Australia). 

29 Administrative pricing refers to the setting of spectrum charges that reflect the 

economic value of the spectrum resource, rather than merely the costs associated with 

licensing and managing the spectrum. The term should not be confused with 

administrative fees, which are set on a cost-recovery basis. 

30 Directive 97/13/EC of the European Parliament and the Council of 10th April 1997 on a 

common framework for general authorisations and individual licences in the field of 

telecommunications services (O.J L 117/15, 07.05.97). 

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Authorisations 31 , Article 6 of the Licensing Directive required fees to cover only the 

administrative costs associated with the authorisation scheme but did not require costs to 

be apportioned to individual applicants. 

Spectrum Charges are charges which reflect the need to ensure the optimal use of scarce 

resources. Article 11.2 of the Licensing Directive allowed Member States to levy such 

charges on a non-discriminatory basis, taking into particular account the need to foster 

the development of innovative services and competition. 

These definitions were chosen simply because in adopting the Authorisation Directive 

(see 7.2.1.1 below) confusing terminology has been introduced with the terms 

administrative charges and spectrum fees in place of administrative fees and spectrum 

charges used in the Licensing Directive. The Consultant’s view is that the terminology of 

the Licensing Directive is more usually used around the World and has therefore been 

retained in this work. 

For the purposes of the study we have also defined a third category of payment, namely a 

Spectrum Fee, (see also 7.2.9 below) which, whilst being based on the amount and type 

of radio spectrum that is licensed, is set by reference to the NRA's overall costs. We 

have treated these spectrum fees separately from other administrative fees and included 

them in the overall category of spectrum charges, partly because of their direct correlation 

with the amount of spectrum used (and hence their potential role in promoting optimal use 

of scarce spectrum resources) and partly because in general they do not appear to bear 

any obvious correlation with the costs relating to the specific licence or service category 

concerned. 

Information has been sought on administrative fees and spectrum charges levied by 

around 30 countries. The countries selected for investigation and listed in Annex 8 were 

selected for their prominence with respect to one or more of the following criteria: 

• A major maritime nation; 

• A major aeronautical nation; 

• A nation with a progressive approach to telecommunications regulation; 

• An important regional country or 

• A British Crown Dependency (Isle of Man) or UK Dependent Territory (Bermuda) 

offering an independent maritime registration regime. 

The four principal radiocommunication activities addressed were: 

i) Aeronautical Radiodetermination equipment (Radiolocation and Radionavigation) 

operating on land and in aircraft and any satellite variants. 

ii) Maritime Radiodetermination equipment (Radiolocation and Radionavigation) 

operating on land and in ships and any satellite variants. 

iii) Aeronautical Radiocommunication equipment operating on land and in aircraft 

and any satellite variants 

iv) Maritime Radiocommunication equipment operating on land and in ships and any 

satellite variants 

31 A similar interpretation would arise in the case of some class licensing systems or 

where no specific licence is issued e.g. the administrative costs of administering such 

schemes may be recovered. 

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To obtain the necessary information a detailed questionnaire (see Annex 9) was 

circulated to NRA contact points, in the case of CEPT member countries the public 

contact point detailed on the ERO web site and in the case of other countries, to 

administrations’ addresses detailed on the ITU web site. The questionnaire was circulated 

in February 2004 and a reminder sent in March 2004. Unfortunately only Hong Kong, 

Turkey and the United Kingdom had replied in detail by the date of compiling this 

Chapter. However a number of administrations replied indicating that human resource 

difficulties would not permit them to complete the questionnaire but provided information 

on web sites containing information pertinent to the questionnaire. Information was also 

gathered from a number of public sources, including other NRA web sites and published 

documents. 

7.1.1 Structure of the Chapter 

The Chapter comprises four main sections, addressing the following specific topics: 

i) Licensing regimes for services using spectrum. 

ii) Approaches to setting administrative fees and spectrum charges 

iii) Conclusions and Trends 

7.1.2 Acknowledgements 

The authors wish to record their appreciation for the assistance provided by NRA 

representatives in the preparation of this report. Completed questionnaires were received 

from Hong Kong, Turkey and the United Kingdom. In addition several 

NRAs/administrations, although not completing the questionnaire, provided detailed 

information in correspondence sent to the Consultant. Where appropriate this information 

has also been included. 

7.2 Summary of European and National spectrum management 

regimes 

7.2.1 European Regulatory Framework 

The European framework for the licensing and authorisation of radio networks using radio 

spectrum falls within the remit of two bodies, namely the European Union (EU) and the 

Conference of European Postal and Telecommunications Administrations (CEPT). The 

EU framework defines the scope for individual licences and general authorisations and 

endeavours to promote a harmonised market for radiocommunication services, 

particularly where international mobility is involved. CEPT, whose membership extends 

beyond the EU and currently includes 46 countries in the European region, is responsible 

for co-ordinating spectrum management and allocation activities at a regional level, within 

the global framework defined by the International Telecommunication Union (ITU). 

The following sections review briefly the role and activities of the EU and CEPT in relation 

to licensing, fees and charges for radiocommunication services. 

7.2.1.1 European Union 

The former EU regulatory framework for the licensing of telecommunications networks 

and services, including those using spectrum, was enshrined in the Licensing Directive 

and facilitated an effective transition from monopoly provision of telecommunications 

networks and services to a competitive, liberalised environment. The main provisions of 

the Licensing Directive which related to licence fees and charges were those in Article 11, 

referred to in section 7.1 above. 

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Increasing convergence between telecommunication, information technology, 

broadcasting and other media sectors prompted the Commission to review the regulatory 

framework for all forms of electronic communication (the "1999 Review"). The 1999 

Review concluded that all transmission networks and services for electronic 

communication should be covered by a single regulatory framework, and a package of 

legislative measures has been proposed by the Commission to this effect. 

The new regulatory framework for electronic communications networks and services were 

applied in all Member States from 25 July 2003 and comprises the following five 

Directives: 

i) On a common regulatory framework for electronic communication networks 

and services (the Framework Directive 2002/21/EC); 

ii) On the authorisation of electronic communications networks and services 

(the Authorisation Directive 2002/20/EC); 

iii) On access to, and interconnection of, electronic communication networks 

and associated facilities (2002/19/EC); 

iv) On universal service and users' rights relating to electronic communications 

networks and services (2002/22/EC); and 

v) On the processing of personal data and the protection of privacy in the 

electronic communications sector (2002/58/EC). 

In addition, a new Decision on a regulatory framework for radio spectrum in the 

Community has been adopted (the Spectrum Decision), to establish a procedural 

framework for the development of spectrum policy and harmonisation of radio frequencies 

(through the use of comitology procedures). The scope of the Spectrum Decision is not 

limited to electronic communication services but extends to other internal market policy 

areas such as transport and R&D. 

The Authorisation Directive 32 requires NRAs to issue general authorisations for all 

electronic communication networks and services, but allows for individual rights of use to 

be granted for radio spectrum where this is necessary, for example to avoid harmful 

interference. NRAs may limit the number of such rights of use only where this is 

necessary to ensure the efficient use of radio frequencies. 

Article 12.1 of the Authorisation Directive requires administrative charges 33 in respect of 

this for general authorisations and rights of use to cover only the following: 

"administrative costs which will be incurred in the management, control and enforcement 

of the applicable general authorisation scheme and of rights of use […], which may 

include costs for international co-operation, harmonisation and standardisation, market 

analysis, monitoring compliance and other market control, as well as regulatory work 

involving preparation and enforcement of secondary legislation and administrative 

decisions…". 

Article 12.1(b) goes on to state that such charges shall: 

32 Council common position adopted on 17 September 2001. 

33 Note this is a change in terminology from the Licensing Directive, which defined such 

payments as Administrative Fees. Administrative Fee is the terminology adopted in this 

report. 

Page 247

"be imposed upon the individual undertakings in an objective, transparent and 

proportionate, manner which minimises additional administrative costs and 

attendant charges." 

Article 13 of the Authorisation Directive provides that Member States may allow NRAs to:- 

"impose fees for the rights of use for radio frequencies… which reflect the need to 

ensure the optimal use of these resources. Member States shall ensure that such 

fees shall be objectively justified, transparent, non-discriminatory, and proportionate 

in relation to their intended purpose and shall take into account the objectives in 

Article 7 of Directive 2002./21/EC [Framework Directive]." 

The Framework Directive 34 requires (Article 8) Member States to: 

"ensure the effective management of radio frequencies for electronic 

communication services in their territory" and to "ensure that the allocation and 

assignment of such radio frequencies by national regulatory authorities are based 

on objective, transparent, non-discriminatory and proportionate criteria". 

The Framework Directive also makes provision for NRAs to permit the transfer of rights to 

use radio spectrum between undertakings, subject to notification to the NRA and on the 

condition that competition is not distorted as a result of such transfer, and that no change 

of use to harmonised spectrum allocations is involved. 

Article 15 of the Authorisation Directive relates to availability of information on fees and 

charges, requiring Member States to: 

"ensure that all relevant information on rights, conditions, procedures, charges, fees 

and decisions concerning general authorisations and rights of use is published and 

kept up to date in an appropriate manner so as to provide easy access to that 

information for all interested parties." 

Again it is necessary to point out that there is a fundamental difference in terminology 

between the Licensing (the terminology used in this report) and Authorisation Directives, 

in that the term Administrative Fees is replaced by Administrative Charges in the 

Authorisation Directive, and charges (relating to scarce resources) are replaced by fees 

for the right of use of radio frequencies. 

7.2.1.2 CEPT ECC 

The European Conference of Postal and Telecommunications administrations (CEPT) is 

the regional regulatory telecommunications body for Europe and currently has a 

membership of 46 European and neighbouring countries. CEPT’s Electronic 

Communications Committee (ECC) co-ordinates the use of the radio spectrum across the 

CEPT region. It has five permanent working groups in the spectrum management field 

concerned with frequency management (FM), spectrum engineering (SE), regulatory 

affairs (RA), WRC preparation and ITU council conference preparation. The RA working 

group has responsibility for matters relating to fees and charges for radio spectrum. 

The ECC’s stated aim is “to ensure that European administrations, industry, broadcasters, 

service providers, operators and users derive maximum benefit from the finite spectrum 

resource”. In line with wider European moves to develop a fully integrated single market, 

ECC is endeavouring to harmonise frequency allocations as far as possible throughout 

Europe. Whilst some harmonisation initiatives have been backed by Commission 

Directives or Decisions, in many other cases the Commission has delegated this 

responsibility to CEPT, whose mandates take the form of ECC Decisions, whereby 

34 Council common position adopted 17 September 2001. 

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administrations commit themselves to the implementation of harmonised use of specific 

frequency bands or standards. 

A number of important elements concerning licensing and associated fees and charges 

are contained and discussed in ECC and ERC (the predecessor of the ECC) 

documentation. In particular ERC Report 53 (May 1998), on the introduction of economic 

criteria in spectrum management and the principles of fees and charging in the CEPT 

countries, is pertinent. The report discusses both the traditional licensing mechanisms 

and a number of aspects of spectrum pricing (administrative pricing, auctions, secondary 

market for spectrum rights) and its potential influence on spectrum re-farming, 

implementation of migration plans, and the adaptation of traditional spectrum fees to 

market conditions. ERC Report 61 on the harmonisation of licensing and ERC Report 76 

on the role of spectrum pricing in spectrum management are also valuable references. 

7.2.2 National Regulatory Regimes 

Most countries require some form of individual licence or authorisation to be held in order 

to utilise radio spectrum for radiocommunications services covered by this document. 

Within Europe, in Belgium, Germany, Greece, France and Luxembourg, a specific 

“spectrum licence” as such is not required, but a frequency assignment must still be 

obtained using procedures akin to those used for spectrum licensing in other European 

Union Member States, with fees and/or charges applying to these assignments. For 

example in Germany in accordance with the 1996 telecommunications law, all services in 

2001 were subject to a one-off frequency fee as specified in the regulation (FGebv) and 

an annual frequency use ‘contribution’ as stated in the FbeitrV. 

The organisational approach to licensing also varies amongst the European Union 

Member States. Some have a single, integrated body dealing with all aspects of 

spectrum and service licensing, whilst others split these activities between different 

organisations. In some cases, the broad policy framework is determined within a 

Ministerial Department, while the day-to-day issuing and enforcement of licences is 

handled by a separate regulatory body which may report to the Ministerial Department or 

may be autonomous. A number of Member States have also established an independent 

telecommunications regulator 35 responsible for overseeing competition aspects and 

enforcing service licence conditions. Although generally appointed by government, 

independent regulators are able to intervene autonomously in areas such as licence 

infringements or anti-competitive practices, and act as the NRA with regard to these 

activities. For the purposes of international representation, there is usually one 

designated NRA in each Member State, although responsibility for specific activities may 

be delegated to other relevant bodies such as independent regulators. For the purposes 

of the study, we have used the term NRA in the generic sense to refer to all bodies 

involved in the licensing and spectrum management processes. 

Table 7-1 lists the main organisations involved in spectrum and service licensing in each 

of the Member States. Note that in most Member States (10 out of 15), there are two 

organisations involved in the licensing process, generally a Ministerial Department 

dealing with policy matters and a separate department or Agency dealing with day-to-day 

licensing activities. In Spain, two Ministerial Departments are involved - the Ministry of 

Economic Affairs supervises the regulator, CMT, while the Ministry of Development's 

SETSI is responsible for issuing licences. In the Netherlands and UK there are separate, 

independent regulators (OPTA and Ofcom) which are involved in some aspects of licence 

35 The term "independent regulator" in this context refers to an organisation that is 

independent of Government. 

Page 249

enforcement (mainly competition aspects) and which command fees from licensees. 

France has separate NRAs dealing with telecommunications (ART) and 

radiocommunications (ANFR). Austria has regional bodies (fernmeldebüro) which are 

involved in issuing and enforcing some radio licences. 

It can be argued that the involvement of several organisations in the licensing process 

may have a negative effect on transparency, however this need not be the case if the 

organisations co-operate in providing information and dealing with the licensing process. 

In general, so long as appropriate links and cross-references are provided between the 

various organisations' web sites the involvement of several organisations does not appear 

to have a bearing on the quality or the accessibility of licensing information. Indeed, given 

the specialist nature of many of the activities related to the licensing process (e.g. 

economic or technical) there can be merits in these being dealt with by separate, 

specialist organisations. 

Page 250

National Regulatory Authority 

for telecommunications 

service using radio spectrum 

B Belgian Institute for Postal Services 

and Telecommunications (BIPT). 

DK Telestyrelsen (National IT and 

Telecommunications Agency – 

NTA). 

D Regulatory Authority for 

Telecommunications and Post 

(RegTP) 

EL National Telecommunications and 

Posts Commission (EETT) 

E Secretaría de Estado de 

Telecomunicaciones y para la 

Sociedad de la Información (SETSI), 

a unit of the Ministry of Science and 

Technology 

Other Organisations involved in Notes 

licensing services, spectrum or 

networks 

Minister of Communications and Infrastructure The Minister is responsible for political matters. BIPT is, inter alia, responsible for management 

The Information Technology (IT) Department 

of the Ministry of Research and Information 

Technology. 

Federal Ministry of Economics and 

Technology 

Ministry of Transport and Communications 

(MTC) 

Ministry of Economic Affairs Comisión del 

Mercado de las Telecomunicaciones (CMT) 

and control of licensing, frequencies and the numbering plan 

NTA is a government Agency under the Ministry of Research and Information Technology 

Fees and charges are set by the Minister for Economics and Technology in consultation with 

other government departments. 

The Ministry has the exclusive competence for strategy as regards the telecommunications 

sector and to introduce legislation. However, the competent authority for the regulation and 

supervision of the telecommunications market is by law EETT, which is the appointed 

independent regulatory authority for 

telecommunications. EETT is also the competent authority for the 

award of the individual licences, allocation of radio 

frequencies, management and supervision of the spectrum use. 

SETSI is responsible for policy making and issuing both telecommunications and radio 

spectrum licences. CMT arbitrates in disputes between network operators and service 

providers, advises SETSI on tariffs and regulatory proposals and deals with applications for 

telecommunications service licences. CMT may also issue licenses when scarcity is not an 

issue. The Ministry of Economic Affairs is responsible for supervision of CMT. 

F Ministry of Telecommunications Agence National des Fréquences (ANFR) Ministry issues public telecommunication licences and is responsible for determining frequency 

fees. ART is responsible for other licensing activities, including licensing of private networks. 

Autorité de Régulation des 

Télécommunications (ART) 

ANFR is responsible for planning, managing and monitoring spectrum use. 

IRL Commission for Communications Department of Communications, Marine & The Department is responsible for telecommunications and radio spectrum regulatory policy. 

Regulation (COMREG) 

Natural Resources 

COMREG is responsible for licensing and enforcement activities. 

I Communications Authority (AGCOM Ministry of Communications AGCOM is responsible for frequency planning and defines licensing procedures. The Ministry 

- Autorità per le Garanzie nelle 

Comunicazioni). 

assigns frequencies to operators and grants radio spectrum licences. 

L Luxembourg Institute of Regulation Ministry of Communications The Ministry is responsible for telecommunications policy and for final granting of licences after 

(ILR) 

analysis of applications by ILR. ILR is responsible for regulation of the telecommunications, 

electricity, postal and gas services. It replaced the former Luxembourg Institute of 

Telecommunications under new legislation in July 2000. ILR is a financially and administratively 

independent authority under the supervision of the Ministry of Communications. 

NL Ministry of Transport, Public Works Radiocommunications Agency (Rijksdienst DGPT is responsible for policy matters 

& Water Management (Directorate voor Radiocommunicatie - RDR) 

General of Telecommunications & Onafhankelijke Post en Telecommunicatie RDR is part of the Transport and Water Management Inspectorate and is responsible for 

Posts - DGPT) 

Autoriteit (OPTA) 

implementation of radio spectrum policy and licensing 

OPTA is responsible for competition and fair trading matters. 

Page 251

National Regulatory Authority 

for telecommunications 

service using radio spectrum 

A Broadcast and Telecommunications 

Regulator (Rundfunk und Telekom 

Regulierungs – RTR GmbH) 

Telekom-Control Commission (TKK) 

Other Organisations involved in 

licensing services, spectrum or 

networks 

Regional Telecommunications Authorities 

(Fernmeldebüro): 

Büro für Funkanlagen und 

Telekommunikationsendeinrich-tungen (BFT) 

Frequency Office (Frequenzbüro) 

Federal Ministry for Transport, Innovation and 

Technology 

Notes 

RTR GmbH replaced former Telekom Control GmbH 

Fernmeldebüro deal with operating licences for radio equipment, also monitoring of 

frequencies and investigation of interference. 

Frequenzbüro deals with international and national frequency co-ordination. 

The Federal Ministry is the supreme telecommunications authority, which prepares laws and 

issues ordinances regarding licensing of radio communication services. 

P Portuguese National 

Ministry of Social Equipment 

BFT will deal with placing on the market, free circulation and use of telecommunication 

equipment according to the R&TTE Directive. 

The Ministry is responsible for government policy on telecomms. 

Communications Authority 

ANACOM reports to the Ministry. ANACOM is autonomous in its decision making and its main 

(ANACOM) 

responsibilities include support to the Ministry in planning legislation and managing radio 

spectrum, granting licences, supervising authorisations and inspect, certify and assess 

conformity of communications equipment). ANACOM is responsible for the national frequency 

plan. The Ministry is responsible for setting spectrum charges. 

FIN The Communications Administration Finnish Communications Regulatory Authority CAD is responsible for legislation, overall regulation and supervision of telecommunications. 

Department (CAD) in the Ministry of (FICORA) 

FICORA is in charge of technical regulations, frequency and number management. FICORA is 

Transport and Communications. 

an Agency under the Ministry of Transport and Communications 

S National Post and Telecom Agency Department of Communications, Ministry of NPTA is in charge of telecommunications regulatory affairs and frequency management. The 

(NPTA) 

Transport and Communications 

Department is responsible for preparing governmental policy on telecomms, overseeing NPTA. 

and institutional representation of the Swedish government at international level 

UK Office of Communications (Ofcom) Department of Trade and Industry (DTI), 

Department for Transport 

Department for Transport is the responsible government department for the CAA and MCA 

Table 7-1 - Organisations responsible for licensing telecommunication services in EU Member States 

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7.2.3 Public availability of information relating to fees and charges 

Many countries and all European NRAs make extensive use of the Internet to aid the 

transparency of their procedures. Access to information has also been helped by the 

activities of CEPT and the EU, including moves to harmonise licensing procedures where 

feasible. 

However, despite these welcome improvements, there is still a wide variation in the 

amount of information made available by individual administrations and NRAs and the 

ease with which this information can be accessed. Whilst some NRAs place all relevant 

information in the web, others restrict this to national official journals or printed information 

sheets which must be procured from the NRA or other Government Department. In some 

cases there appears to be no publicly available information concerning fees and charges 

for certain services. 

When informing the consultant that it was not possible to complete the questionnaire as 

requested many administrations provided their web address and some URLs of key pages. 

Some administrations have not replied at all and attempts were made by the consultant to 

obtain information where possible. Table 7-2 below is a compilation of general information 

obtained from the Web on the countries listed in Annex 8. 

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COUNTRY 

QUESTION 

2.1.1 - National Organisations with Responsibilities for Granting of Radio Frequencies & Related Licences, & Setting administrative Fees or Spectrum Charges 

Australia The Australian Communications Authority (ACA) – see http://www.aca.gov.au/ ACA is responsible for regulating telecommunications and radiocommunications, including 

promoting industry self-regulation and managing the radio frequency spectrum. ACA also has significant consumer protection responsibilities. 

Austria Bundesministerium für Verkehr, Innovation und Technologie (BMVIT) – see http://www.bmvit.gv.at/sixcms/ (no English). 

Bahamas Bahamas Telecommunications Corporation (BATELCO) – see http://www.btcbahamas.com/main_flash.htmlThe Bahamas Telecommunications Company Ltd (BTT) has been 

the regulator and provider of telecommunications services in The Bahamas for more than 100 years. 

Public Utilities Commission (PUC) – see http://www.pucbahamas.gov.bs/ The Public Utilities Commission (PUC) was established on March 1, 2000 under the provisions of the 

Public Utilities Commission Act, 1993. It was established for the economic regulation of electricity, telecommunications, and water and sewerage services. However the PUC only 

regulates telecommunications, including management of the radio frequency spectrum, at this time. 

Belgium The Belgian regulatory body for postal services and telecommunication (BIPT) – see http://www.bipt.be/bipt_E.htm Established by the Act of 21 March 1991, BIPT is the 

regulatory body of the postal and telecommunications sector in Belgium. The Institute is responsible for strategic, regulatory and operational tasks, tasks regarding the settlement of 

disputes between operators and regulation of the whole sector. 

Bermuda The Ministry of Telecommunications & E-Commerce – see http://www.mtec.bm/ The Department of Telecommunications is responsible for: Broadcasting, Coastal Stations, the 

Frequency Spectrum: e.g., cellular telephones, Radio Communication of All Types , Receiving Systems 

Brazil Ministry of Communications – see http://www.mc.gov.br/fale_english.htm (almost no English) The Ministry of Communications is the body of the executive branch in charge with 

the elaboration and accomplishment of the public policies regarding communication. Its activities comprise three fundamental areas: Broadcasting, Postal Services, and 

Telecommunication. In the Broadcasting Secretariat, the Ministry administrates the permissions of radio and open TV, since the beginning of the public tender process to the 

effective working of the winning bidders, based on specific legislation, on laws and several rules. In order to supervise the sector of telecommunication and broadcasting the 

Ministry reckons on the technical procedures of its regulatory agency called Anatel, National Agency of Telecommunication. 

National Agency of Telecommunication (Anatel) – see http://www.anatel.gov.br/home/default.asp (no English) 

Canada Industry Canada – see http://www.ic.gc.ca/cmb/welcomeic.nsf/icPages/Menu-e Industry Canada was the Department of Trade and Commerce, which was created on 

December 3, 1982. The Minister is responsible for many Acts including Telecommunications Legislation, Marketplace and Trade Regulation, Canadian Intellectual Property Office 

(CIPO) Legislation, and Consumer Legislation. 

Spectrum Management and Telecommunications (SITT) – see http://strategis.ic.gc.ca/epic/internet/insmt-gst.nsf/vwGeneratedInterE/home?OpenDocument SITT are a 

department within Industry Canada responsible for: licence applications; spectrum auctions; broadcasting; radiocommunications (including spectrum licensing, cell phone and 

amateur radio services); telecommunications; consumer information; Canada Gazette and public notices; references (including circulars, licence fees, and the Canadian Frequency 

Allocation table); and utilities (equipment lists). 

Canadian Radio-television and Telecommunications Commission (CRTC) – see http://www.crtc.gc.ca/eng/welcome.htm The CRTC is an independent agency responsible for 

regulating Canada's broadcasting and telecommunications systems. 

China National Radio Spectrum Management Centre - see http://www.srrc.gov.cn/gg.htm (no English). 

Cyprus Ministry of Communications and Works of the Republic of Cyprus – see. http://www.mcw.gov.cy/mcw/mcw.nsf/Main?OpenFrameSet Department of Electronic 

Communications is the Government’s advisor on telecommunications policy matters including those related to harmonisation with the Acquis Communitaire of the European Union. 

It coordinates and manages the Government’s activities on all telecommunications technical issues such as satellite communications, broadcasting networks of radio and TV 

stations. It also manages the radio frequency spectrum. It supervises the activities of the Cyprus Telecommunications Authority in accordance with the Telecommunications 

Services Law, on behalf of the Minister of Communications and Works. 

Denmark National IT & Telecom Agency - see http://www.itst.dk/mainpage.asp 

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Finland The Finnish Communications Regulatory Authority (FICORA) – see http://www.ficora.fi/englanti/radio/index.htm FICORA oversees the use of radio frequencies in Finland. The 

objective is to offer to all users radio frequencies that are as free from interference as possible. Radio spectrum management aims at ensuring that technically and economically 

feasible radio frequencies can be assigned future radio systems as well. This must not, however, restrict the use of radio frequencies for present radio systems. 

France Agence Nationale des Fréquences – see http://www.anfr.fr/ (very little English). 

Germany The Federal Ministry of Economics and Labour (BMWA) – see - http://www.bmwa.bund.de/Navigation/Service/english.html BMWA = inisterium für Wirtschaft und Arbeit. The 

Radio Spectrum Policy Group (RSPG) – see http://rspg.groups.eu.int/Default.htm Public consultation on secondary trading of rights to use radio spectrum. The Radio Spectrum 

Policy Group (RSPG) was established under the Commission Decision 2002/622/EC as one of the actions following the adoption of the Radio Spectrum Decision 676/2002/EC. The 

RSPG shall adopt opinions, which are meant to assist and advise the Commission on radio spectrum policy issues, on co-ordination of policy approaches and, where appropriate, 

on harmonised conditions with regard to the availability and efficient use of radio spectrum necessary for the establishment and functioning of the internal market 

Regulatory Authority for Telecommunications and Posts (Reg TP) – see http://www.regtp.de/en/index.html Reg TP is a structurally separate authority with the maximum 

possible independence is needed to perform these tasks. The Regulatory Authority for Telecommunications and Posts was therefore set up as provided for by the 

Telecommunications Act, in force since 1 August 1996. It is a higher federal authority within the scope of business of the Federal Ministry of Economics and Labour, and has its 

headquarters in Bonn. The Regulatory Authority superseded the Federal Ministry of Posts and Telecommunications and its subordinate Federal Office. 

Greece Ministry of Transport & Communications (but no details found) 

Hong Kong The Office of the Telecommunications Authority (OFTA) - see http://www.ofta.gov.hk/frameset/home_index_eng.html OFTA is the statutory body responsible for regulating the 

telecommunications industry in Hong Kong. The work of OFTA in relation to the licensing of radiocommunications services/systems covers the following main areas: regulating 

telecommunications installations/services; tracking down illegal radiocommunications activities; and managing radio spectrum and co-ordinating satellite orbital positions. 

Ireland The Commission for Communications Regulation (ComReg) – see http://www.comreg.ie/ ComReg was established on 1 December 2002. It is the statutory body responsible 

for the regulation of the electronic communications sector (telecommunications, radiocommunications and broadcasting transmission) and the postal sector. They are the national 

regulatory authority for these sectors in accordance with EU law, which is subsequently transposed into Irish legislation. For Radiocommunications - see 

http://www.comreg.ie/sector/default.asp?TV4=TTX&S=4&print=&id=&q=&sTV4=TTX&TV4Exp=N 

Italy The Ministry of Communications – see http://www.comunicazioni.it/en/index.php The current Ministry of Communications framework (previously Ministry of Posts and 

Telecommunications), in layman's terms, stems from the reshaping of its central administration headquarters, then self-governing, into a public, economic body. They grant 

licences, authorizations and permissions, adopting the relevant provisions taking great care of their observance. 

Japan Telecommunications Bureau of the Ministry of Public Management, Home Affairs, Posts and Telecommunications – see http://www.tele.soumu.go.jp/e/index.htm 

The Radio Policy Division plans, designs and promotes the general policies for the radio use, allocates the frequency and executes radio operators certificates system. 

appropriating a portion of the surplus. 

Korea Ministry of Information and Communication Republic of Korea (MIC) – see http://www.mic.go.kr/etc/20040401_popup01.jsp One of its umbrella Agencies is the Korea 

Communications Commission (KCC) – see http://www.kcc.go.kr/eng/e_main1.php 

The Korea Communications Commission (KCC) is an independent regulatory agency. Established by the Article 37 of Telecommunications Basic Act, it is charged with 

deliberating issues concerning fair competition environments and consumer protection of telecommunication services, and with arbitrating disputes among telecommunication 

service carriers and between users and carriers. 

Lebanon Lebanese Ministry of Telecommunications – see http://www.mpt.gov.lb/index.htm No information about radio communications. 

Liberia No information available from the Internet. 

Luxembourg Institut Luxembourgeois de Régulation - see http://www.etat.lu/ILR/content.html (No English) 

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QUESTION 


Malta The Ministry for Transport and Communications - see http://www.mtc.gov.mt/ The Ministry for Transport and Communications is the national entity responsible for transport 

and communications. This Ministry is primarily charged with the formulation and implementation of policy in these areas with the aim of ensuring that the country maintains and 

improves upon its performance in these fields. 

The Wireless Telegraphy Department – see http://www.wtd.gov.mt/index.htm ensures that all radiocommunication services in Malta operate efficiently, without causing harmful 

interference, and also ensures that licensed users of wireless telegraphy equipment abide by the conditions of their licence. 

Netherlands Ministry of Economic Affairs - see http://www.minez.nl/default_bel.asp?pagina=english The Dutch Ministry of Economic Affairs (EZ) operates as a true partner in trade and 

industry in the Netherlands. This small, dynamic department plays an important role in creating the best possible circumstances for economic activity in the Netherlands, stimulating 

innovation and growth in vital sectors. EZ seeks and maintains a permanent dialogue with companies on strategic issues, also offering subsidies aimed at strengthening the 

competitive edge of those industries that qualify to use them. 

The Netherlands Radiocommunications Agency - see http://www.agentschap-telecom.nl/ The Netherlands Radiocommunications Agency is the government agency responsible 

for frequency planning and management in the Netherlands. Primary activities of the Radiocommunications Agency are frequency planning, issuing licences for frequency use, and 

enforcement of frequency use. 

New Zealand The Ministry of Economic Development - see http://www.med.govt.nz/ The Radio Spectrum Management Group - see http://www.med.govt.nz/rsm/about/index.html part of the 

Operations Branch of the Ministry of Economic Development, administers the radio spectrum under the auspices of the Radiocommunications Act 1989 and its subordinate 

regulations, the Radiocommunications Regulations 2001. 

Norway The Norwegian Post and Telecommunications Authority - see http://www.npt.no/portal/page?_pageid=78,41174&_dad=portal&_schema=PORTAL Norwegian Post and 

Telecommunications Authority (NPT) is an autonomous administrative agency under the Norwegian Ministry of Transport and Communications, with monitoring and regulatory 

responsibilities for the postal and telecommunications markets in Norway. The NPT is self-financed, primarily through fees and charges. 

Pakistan Pakistan Telecommunications Authority (PTA) - see http://www.pta.gov.pk/ PTA was formed under the Pakistan Telecommunications Reorganisation Act, 1996. It is a regulatory 

body, which regulates the establishment, operation and maintenance of telecommunications services. It also promotes and protects the interests of telecommunication service 

providers and users, ensuring that the consumers get high quality services at competitive prices, with a reasonable range of choice. 

Panama Ente Regulador de Los Servicious Publicos – see http://www.ersp.gob.pa/consulta.asp (no English) 

Portugal Autoridade Nacional de Comunicações (ANACOM) - see http://www.anacom.pt/index.jsp?categoryId=2958 ANACOM is the regulator, supervisor and representative of the 

communications sector in Portugal. Autoridade Nacional de Comunicações (ANACOM) is the new designation of the Instituto das Comunicações de Portugal, after the publication 

of the new statutes in 6 of January of 2002. It is the regulatory authority for telecommunications and postal communications, in accordance with the base laws for 

telecommunications and postal services (article 5 of Law no. 91/97, of 1 August and article 18 of Law no. 102/99 of 26 July). 

Russian Federation Ministry for Communications and Informatization of the Russian Federation see - http://english.minsvyaz.ru/site.shtml?id=22 The Russian Federation Ministry for 

Communications and Informatization (Minsvyazi of Russia) is a federal executive power structure, which implements the state policy and management in the communications (tele 

and postal) and informatization areas, and the related coordination of other federal executive power structures. 

State Commission on Radio Frequencies (SCR) - see http://english.minsvyaz.ru/site.shtml?id=37 Responsible for the Assignment of the radio-frequency bands for the radioelectronic 

devices (REMs) developed (modernized), manufactured in the Russian Federation and bought from abroad; Planning of distribution and utilization of the radio-frequency 

bands, orbits and standing points (areas) of the man-made Earth satellites for the satellite systems (networks), which fall within the RF jurisdiction; Settlement of issues of the 

utilization by Russian operators of the radio-frequency bands for the exploitation in the RF territory of the satellite communication ground stations working via the man-made Earth 

satellites of the foreign satellite systems (networks); Determination of the basic technical features and requirements towards REMs during their development, production and supply 

to the national market; Coordination of general requirements towards means and systems of the active protection of public information in part of their electromagnetic compatibility 

(EMC) with other REMs; Coordination of actions related to provision of the international-legal protection of the frequency assignments to the RF REDs, and guidance over the 

coordination and registration of the nations REDs frequencies at the International Telecommunication Union (ITT). 

Singapore The Infocomm Development Authority of Singapore (IDA) – see http://www.ida.gov.sg/idaweb/marketing/index.jsp The Infocomm Development Authority of Singapore (IDA) is 

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QUESTION 


at the heart of the New Economy where technology, capital, knowledge and talent are being pushed beyond national boundaries. 

South Africa Department of Communications – see http://docweb.pwv.gov.za/ The Department of Communications is the public service arm of the Ministry for Posts, Telecommunications and 

Broadcasting. The Department is the centre of policymaking and policy review for the Posts, Telecommunications and Broadcasting sectors in the country. This includes policy 

making that affects state-owned enterprises such as Telkom SA Limited, South African Post Office (Pty) Ltd, Sentech and the SABC, as well as the regulators – the Independent 

Broadcasting Authority, the Universal Service Agency and the South African Telecommunications Regulatory Authority. All these, including the Department, fall under the Cabinet 

portfolio of Posts, Telecommunications and Broadcasting. 

The Independent Communications Authority of South Africa (ICASA) - see http://www.icasa.org.za/ The Independent Communications Authority of South Africa (ICASA) is the 

regulator of telecommunications and the broadcasting sectors. It was established in July 2000 in terms of the Independent Communications Authority of South Africa Act No.13 of 

2000. It took over the functions of two previous regulators, the South African Telecommunications Regulatory Authority (SATRA) and the Independent Broadcasting Authority (IBA). 

The two bodies were merged into ICASA to facilitate effective and seamless regulation of telecommunications and broadcasting and to accommodate the convergence of 

technologies. 

Spain Ministry of Science and Technology – see http://www.mcyt.es/english_mcyt/indexingles.htm (no useful data in English available). 

Sweden National Post and Telecom Agency – see http://www.pts.se/default.asp?SectionID=&ItemID=&LanguageID=EN Post- och telestyrelsen, PTS, the Swedish National Post and 

Telecom Agency, is the governmental authority for all issues relating to the telecoms, IT, radio and postal services. One of our key tasks is to ensure the development of functioning 

postal and telecom markets. We actively promote healthy competition, supervise price trends and have the consumer's interests at heart. PTS also issues regulations and ensures 

that existing legislation is followed. 

Turkey TELECOMMUNICATIONS AUTHORITY – see http://www.tk.gov.tr/Eng/english.htm (nothing available in English) 

UAE Ministry of Finance & Industry - see http://www.fedfin.gov.ae/ The UAE's telecommunications sector is the most highly developed in the region, with state telecommunications 

giant Etisalat also being one of the region's top companies. Through its 34 per cent owned affiliate, Thuraya, Etisalat will launch its own satellite during 2000, this being intended to 

serve up to 1.9 million users in 49 countries from the Atlantic to the Indian sub-continent and Central Asia. Locally, there are over 450,000 mobile telephones, while access to 

Internet services, has been available since 1995, with connection and usage rates being continually reduced as Internet connections grow A complete e-commerce service, 

Contrast, was launched in 1999. Now planning to diversify into cable television, Etisalat is also a key partner in the FLAG (Fibre-Optic Link Around the Globe) network, the world's 

longest operating submarine cable system, which links Europe to Asia and the Far East. 

Emirates Telecommunications Corporation (Etisalat) – see http://www.etisalat.ae/index2.htmEmirates Telecommunications Corporation - Etisalat came into being on 30th 

August 1976. The Corporation provides telecommunication services to the United Arab Emirates and is one of the leading service providers in the Middle East Region. It is one of 

the largest and most successful companies in the Middle East, controls the telecommunications business in the UAE. 

UK Office of Communications (Ofcom) see - http://www.ofcom.org.uk/ Ofcom is the regulator for the UK communications industries, with responsibilities across television, radio, 

telecommunications and wireless communications services. 

USA The Federal Communications Commission (FCC) - See http://www.fcc.gov/ The Federal Communications Commission (FCC) is an independent United States government 

agency, directly responsible to Congress. The FCC was established by the Communications Act of 1934 and is charged with regulating interstate and international communications 

by radio, television, wire, satellite and cable. The FCC's jurisdiction covers the 50 states, the District of Columbia, and U.S. possessions. The Federal Communications Commission 

is responsible for regulating aviation and marine radios. 

Table 7-2 Public information concerning the countries to which the Questionnaire was sent 

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7.2.4 Legislative basis of licensing, fees and charges in European Member 

States 

In most Member States, there are two levels of legislation which relate to the licensing of 

telecommunications and other radiocommunication services. Primary legislation, i.e. Acts 

or Laws enacted by national Parliaments, typically provide the broad framework for 

licensing, such as defining the role and responsibilities of the NRA and the circumstances 

under which fees or charges can be levied. Secondary legislation, in the form of decrees, 

executive orders or statutory instruments is typically used to set the level of fees or 

charges, or to transcribe European Directives into national law. All Member States have 

enacted primary legislation as part of the telecommunications liberalisation process, and it 

is this legislation that is used as the basis for setting administrative fees for service 

licences. In many cases this legislation also addresses spectrum licensing. However 

Denmark, Ireland, Finland and Sweden have separate primary legislation addressing radio 

and telecommunications licensing, whilst in the UK a mixed regime is in operation with 

some separate primary legislation such as the Wireless Telegraphy Act (1949 and 1998) in 

operation alongside the Communications Act (2003). This Act inter alia provided for the 

formal powers of the Secretary of State for Trade and Industry to grant wireless telegraphy 

licences under section 1 of the Wireless Telegraphy Act 1949 to transfer to the Office of 

Communications (“Ofcom”). In some cases the radio legislation predates liberalisation 

(Ireland - 1926, Belgium - 1979, Finland - 1988), though in each case the legislation has 

been amended periodically to cope with new developments. 

Table 7-3 below summarises the main primary legislation relating to telecommunications 

service and radio spectrum licensing in each of the European Member States. 

However other legislation may be pertinent for the licensing of aircraft and ships for 

example the national legislation which transposes the European Union’s Marine Equipment 

Directive (96/98/EC and subsequent modifications) into national law as well as national 

legal and regulatory provisions that implement Articles 29 and 30 of the ICAO Convention 

which require aircraft stations on international flights to be issued with a licence. In the UK 

the latter is covered by the Air Navigation Order, Article 76 and Schedule 11. 

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Principal Legal Basis (Primary Legislation) relating to National Licensing Regime 

B Act of 30 July 1979 on radio communications: establishes the general condition for the provision of radio communications. The Act was implemented by the Royal Decree of 15 October 1979 and the 

Ministerial Decree of 19 October 1979 concerning private radio communications. Specific decrees on spectrum charges are issued under this Act. 

DK Regulation of radio frequency allocations and assignments is regulated by Act No. 394 of 10 June 1997 on Radio Communications and Assignment of Radio Frequencies (the Act on Frequencies) as amended 

by Act No.1011 of 23 December 1998, Act No. 1096 of 29 December1999 and by Act No. 232 of 5 April 2000. 

D Telecommunications Act of 25 th July 1996: set up the regulatory framework and provided the legal basis for establishment of the NRA (RegTP). The Act defines the scope of licensing for telecommunications 

networks, services and radio spectrum. 

EL Law 2867/2000, introduced on 1 st January 2001, defines the regulatory framework for the Greek telecommunications market. The Law enhanced the role of the independent regulator, EETT, which is now the 

competent authority for the award of individual licences, allotment of frequency bands, assignment of individual radio frequencies and the management and supervision of spectrum use. 

E Law 11/1998, of 24 th April, General Telecommunications Act: defines broad framework of telecommunications regulation in Spain, including scope of general authorisations and individual licences, 

management of and access to the radio spectrum and levels of administrative fees and spectrum charges. Current spectrum charges are specified in Article 66 of Law 13/2000. 

F Telecommunications Act, 1996: defines licensing requirements and fees for telecommunications networks and services, including those using the radio spectrum. Royalties (annual fees) are defined in Articles 

L.33-1, L.33-2 and L.34-1 of the posts and telecommunications code. 

IRL Wireless Telegraphy Acts 1926 - 1988: govern licensing or exemption from licensing of radiocommunications apparatus. Licences are granted under section 5 of the Act to keep, have possession of, install, 

maintain, work and use apparatus in a specified place. 

I Law no. 249 of 31 st July 1997 on the Creation of the telecommunications NRA (AGCOM) and provisions on telecommunications and broadcasting systems. 

L Telecommunications Act of 21 st March 1997 set up the regulatory framework for telecommunications and provided legal basis for establishment of NRA (ILR). Article 7 of the Act defines which types of 

network or service require individual licences. Articles 29 - 32 define the approach to managing and assigning frequencies, including provision for Grand-Ducal Decrees to determine specific frequency 

allocations and to set fees and charges for access to spectrum. 

NL Telecommunications Act (T Act): States that a licence is required for the use of frequencies and must be requested from the State Secretary of Transport, Public Works and Water Management. Under the T 

Act, licences are only required for the use of frequencies and numbers. 

A Federal Telecommunications Law of 1 August 1997 (as amended) provides regulatory framework and legal basis for the establishment of the NRA. The Law distinguishes between granting of authorisations for 

Page 259

importation, sale, ownership, installation and operation of radio equipment and granting of Konzessions for provision of telecommunication services using radio equipment. The scope of the Law is to promote 

competition in telecommunications and includes the efficient and interference-free use of available frequencies. Specific clauses relate to annual spectrum charges for all authorised radio networks and onceoff 

charges for spectrum assignment. 

Other measures include a revision of the Telecommunications Law and a complete reorganisation of the regulatory authorities, establishing a Communications Commission and the Rundfunk und Telekom 

Regulierungs-GmbH (RTR GmbH, formerly Telekom Control ) 

. 

P Basic Telecommunications Law (no. 91 of 1 st August 1997): defines the general regulations for the setting up, management and operation of telecommunications networks and the provision of 

telecommunications services. 

FIN Telecommunications Market Act (396/1997): set up legal framework for telecommunications and provided legal basis for creation of NRA (FICORA) 

The Radio Act (517/1988) govern radio equipment and its possession and use as well as the protection of radiocommunications from interference 

S The Telecommunications Act (1993:597) and the Radiocommunications Act (1993:559), both with later amendments, set up the regulatory framework for telecommunications and the establishment of the NRA 

(National Post and Telecommunications Agency). 

UK Wireless Telegraphy Acts 1949 and 1998 covers licensing of radiocommunication networks and apparatus. The 1998 Act updated earlier legislation, making provision for auctions and administrative pricing. 

Communications Act 2003 authorises the trading of radio frequencies. 

Table 7-3 Legal Basis of Spectrum Licensing in EU Member States 

Page 260

7.2.5 Change of Control Rules relating to radio spectrum licences 

Telecommunications and radio spectrum licences are generally not transferable without 

the approval of the NRA or other national government representative. Typically, specific 

provisions relating to the transfer of licences under specific circumstances (such as a 

change of ownership of the licence holder) are included within national legislation or within 

individual licences. Details of specific change of control rules applied by European 

Member States are summarised in Table 7-4 below. 

B For private networks (fixed links / satellite), authorisations and frequency assignments can not be 

transferred but must be cancelled and new ones issued. 

DK Licences may only be assigned wholly or partly to other parties if the licence holder has obtained the 

consent of the NTA thereto, prior to the assignment. Such assignment includes indirect assignment 

such as stocks, shares or other ownership interests that involve changes in the control of the licence 

holder. Section 7 of the Mobile Communications Act states that licences may not be assigned in 

whole or in part without the approval of the NRA. Assignment in this context also relates to indirect 

changes of control of the licensee. Assignment to a third party of some of the licensed spectrum (i.e. 

spectrum trading) is also not permitted. 

D Telecommunications licences may be transferred in accordance with § 9 of the Telecommunications 

Law. Written agreement of the NRA is required. Radio frequencies cannot generally be transferred 

but must be handed back to the NRA and re-assigned. 

EL Licence transfer requires the prior approval by EETT, who will ensure that the new licence holder can 

fulfil the licence terms and that no restrictions in competition arise. 

E The new owner must maintain existing licence obligations. Where scarce spectrum resources are 

involved, there is a minimum time before takeovers or mergers can take place. Competition rules do 

not allow large operators to take over smaller competitors. 

F Any significant change of capital structure of licensed PTO must be notified to ART, but there are no 

specific rules to prevent such changes other than general competition law. 

IRL Service and spectrum licences are not transferable and COMREG consent is required for any change 

of control or ownership. 

I An individual licence can be transferred to third parties only after the approval of the NRA. 

L Conditions of transfer of individual licences are included in individual licence schedules. Licences are 

generally not transferable. 

NL A licence may be transferred to another upon application by the holder of that licence with the 

permission of the Minister. Conditions may be attached to such permission, which may be altered from 

time to time (article 3.8 of the T Act). 

A §16 of the Telecommunications Law states that a licence can only be transferred with the agreement 

of the Regulator. For operation of authorised radiocommunication equipment the licensee has to 

inform the Fernmeldebüro (regional offices) of any change of ownership. 

P Decree Law also states that if an entity wishes to transfer a licence it must obtain ANACOM's 

authorisation. 

FIN No specific change of control rules. 

S Transfer of an individual licence is not permitted. 

UK Licences are "not assignable", i.e. legal rights to the licence cannot be transferred to another 

undertaking. Subject to competition issues not being distorted, the licensing authority will normally 

endeavour to issue a replacement licence to a new undertaking on the same terms. 

Table 7-4 - NRA "Change of Control" rules for radio spectrum licences. 

In addition to the indicated situation in the countries listed in Table 7-4 above, Hong Kong 

and Turkey have indicated that the transfer of a licence is not permitted. In Australia the 

Radiocommunications Act 1992 was amended to permit the transfer of apparatus licences. 

When an apparatus licence is transferred, it will remain in force for the balance of the 

original term of the licence (this is subject, to the possibility of any later administrative 

action taken by the Australian Communications Authority (ACA) to suspend or cancel the 

licence). The transferred licence will also be subject to the same conditions as applied to 

the licence immediately before the transfer. 

Page 261

The transfer provisions of the Act also give the ACA the power to make a determination 

should it be necessary to prohibit the transfer of certain types of licences, or to specify 

circumstances in which a licence may not be transferred. 

7.2.6 Relationship between Licensing, Fees and Charges. 

Spectrum licensing concerns the right to access a potentially scarce resource and 

therefore may command charges that are in excess of the cost of licensing, to reflect the 

scarcity value of the resource. 

There are a number of approaches to setting spectrum charges where there is scarcity and 

these are addressed in section 7.2.10. It should however be noted that spectrum need not 

always be treated as a scarce resource. In some frequency bands and geographic areas, 

there may be little foreseeable demand for spectrum and in such instances it would not be 

appropriate to levy charges above those required to cover costs. Hence it may be 

appropriate for some spectrum licences to be subject to cost-based fees and others 

subject to above-cost charges, depending upon whether there is likelihood of scarcity. In 

some countries, there is a mixed approach to spectrum licensing, with fees based on the 

costs of specific spectrum management or licensing activities and a separate spectrum 

charge applied only where there is a scarcity. 

Some countries apply spectrum fees which, whilst set with reference to the NRA’s overall 

costs, are apportioned to individual licensees on the basis of the amount of spectrum 

and/or frequency band licensed. Table 7-5 provides a summary of the types of fees and 

charges that are applied in each European Union Member State. 

Finally, it should be noted that cost-based administrative or spectrum fees may incorporate 

elements of indirect costs which, whilst not relating directly to the licence or authorisation 

concerned, nevertheless are legitimate and necessary costs associated with the running of 

the NRA. The apportionment of such costs, which are addressed in more detail in section 

7.2.8.4, is a complex issue and is open to various interpretations which can lead to 

significant variations in the level of fees in different countries. 

Administrative 

fees for spectrum 

licence 

Spectrum fees 

(cost-based) 

B Yes (satellite only) Yes (not all 

services) 

DK Yes Yes Yes 

D Yes Yes Yes 

EL No Yes (not all 

services) 

Spectrum charges 

(above cost) 

Yes (auction or 

administrative 

pricing ) 

Yes (auction), 

E No No Yes (administrative 

pricing) 

F Yes No Yes (administrative 

pricing) 

IRL No Yes (not all 

services) 

I Yes Yes (not all 

services) 

L No Yes No 

Yes (administrative 

pricing) 

Yes (auction or 


pricing ) 

NL No Yes Yes (Auction) 

A Yes Yes (not all 

services) 

P Yes Yes No 

Yes (Auction) 

Page 262

FIN Yes Yes No 

S Yes No No 

UK No 36 No Yes (auction or 


pricing ) 

Table 7-5 – General situation concerning the application of fees and charges in EU Member 

States 

Note that all Member States apply administrative fees of some description, in some cases 

for spectrum licences and in some cases for network / service licences. The latter only 

apply to public telecommunications networks. 

In those countries that do not apply administrative fees for spectrum licensing, relevant 

costs are recovered either by means of cost-based spectrum fees or are recovered from 

the proceeds of administrative pricing or auctions. For cost-based spectrum fees, all the 

NRA’s relevant costs are recovered from all the licensees, but the amount recovered from 

individual licensees is a function of the amount and type of spectrum resource that is 

licensed. 

7.2.7 Purpose of Administrative Fees and Spectrum Charges 

There are two principal reasons why it is necessary to levy fees and charges for 

radiocommunications services. Firstly, administrative fees are required to cover the costs 

associated with issuing licences, monitoring market behaviour and enforcing licence 

conditions. 

Secondly, spectrum charges should reflect the need to provide an incentive for those using 

spectrum to do so in the most efficient manner and to ensure optimum use of scarce 

spectrum resources. Charges may also be applied to encourage users who have a viable 

alternative (e.g. the use of fibre optic cable instead of fixed radio links) to vacate spectrum, 

making way for new market entrants or new service offerings which value spectrum more, 

thus optimising the economic benefits of the use of the spectrum. In a competitive bidding 

scenario, spectrum charges can also provide an objective and transparent means of 

awarding licences where the number is limited due to the scarcity of spectrum. 

The radio spectrum is a finite resource, representing a relatively small amount of the 

broader electromagnetic spectrum that includes infra-red and optical frequencies with 

many orders of magnitude more bandwidth. The value of spectrum over other electronic 

communication media is not so much its capacity for information transmission, but its 

ability to convey such information to remote users under a wide variety of scenarios, 

including a full mobile capability. This value is particularly apparent in mobile and 

broadcast applications, where radio spectrum provides the only means for wide area 

wireless delivery of services over non-line of sight paths. 

The attractiveness of certain parts of the spectrum is further enhanced by the physical 

properties of the spectrum (notably the available bandwidth, geographic range and re-use 

capability) and the service to which the spectrum has been allocated by the ITU and 

regional bodies such as the CEPT. In practice, terrestrial broadcasting and wide area 

mobile communications are constrained to frequencies below 3 GHz (to provide wide area 

non-line of sight coverage), whereas line of sight applications such as terrestrial fixed links 

36 [In the UK cost based administrative fees apply for aeronautical and maritime services. 

Spectrum charges or administrative pricing have not so far been implemented for 

aeronautical and maritime services.] 

Page 263

or satellite systems can take advantage of the greater bandwidths available in the higher 

frequency bands. 

Access to spectrum is required by a wide range of users, including non-commercial 

organisations such as the military, public safety organisations and navigation services. 

Much of this spectrum must also be in the sub-3GHz region, further reducing the spectrum 

available for mobile and broadcast applications. Effective utilisation of this remaining 

spectrum requires careful management on the part of the NRA and, where demand 

exceeds supply, a means of assigning spectrum to those who are most likely to make 

optimum use of scarce resources. Fees and charges relating to spectrum address these 

two aspects, i.e. recovery of the costs associated with good spectrum management 

practice and providing a financial incentive to users to make most efficient use of this 

limited resource. 

7.2.8 Approaches to setting Administrative Fees 


Administrative fees enable NRAs to recover the costs associated with spectrum 

management and licensing. Some of these costs are incurred prior to licence issue and 

may therefore be recovered as a single payment when the licence is issued. Other costs 

are ongoing, relating to maintenance and enforcement of licences and the broader 

management of the radio spectrum. There are also indirect costs incurred by the licensing 

body, such as personnel, training or other overheads, which need to be recovered within 

the administrative fee framework. 

The following sections address each of these three cost elements. We then go on to 

review the main approaches currently used by Member States to determine the appropriate 

level of administrative fees 

7.2.8.2 Costs associated with Licensing 

Licensing costs fall into two broad categories, namely those associated with the 

preparation and issuing of the licence or authorisation, and those associated with 

maintenance and enforcement. The former may include costs associated with any 

necessary enabling legislation and the holding of auctions or comparative processes 

hereafter referred to as ‘beauty contests’ in this Report, in addition to the direct costs of 

drafting and issuing the licence. Ongoing costs include those associated with enforcing 

licence conditions. It may also be necessary to update licences from time to time to take 

account of changes in national or European legislation. There are two approaches 

generally applied to the recovery of such costs, namely the application of a fixed annual 

fee for each type of licence, and the application of a levy based on the licensee’s turnover 

or profitability. Whilst a fixed fee is more directly related to the costs associated with a 

specific licence, a levy may be seen as more equitable in terms of the apportionment of 

costs to large and small players. 

7.2.8.3 Costs associated with Spectrum Management 

Management of the radio spectrum is a complex task involving long-term, strategic 

planning, day-to-day assignment of spectrum to individual users, enforcement of licence 

conditions and obligations, and dealing with unlicensed or unauthorised users. Depending 

on the national regulatory regime, these functions may be undertaken by a single body or 

be delegated to different bodies either within or outside government. Similarly, costs may 

be allocated directly to specific functions or services, or aggregated, either to broad groups 

of services or functions or across the entire spectrum management regime. In some 

cases, costs may not even be specifically allocated to spectrum management, but may 

include other associated regulatory aspects such as enforcement. 

Page 264

Among the specific, identifiable costs which can be directly associated with spectrum 

management are: 

• Participation in international fora, 

• Licensing of radiocommunication services. 

• Co-ordination. 

• Enforcement of licence conditions. 

• Policing the spectrum. 

7.2.8.4 Indirect costs 

In addition to the direct costs relating to the process of licensing and maintenance of a 

specific radiocommunication licensee, there are a number of functions that NRAs 

undertake that can be considered as ‘indirect costs’ to the process of spectrum 

management. Typical indirect costs could include: 

• Research and development of new technologies to the benefit of spectrum users, 

• Market surveillance, 

• Marketing and public relations, 

• National database management, 

• Participation in a variety of international regulatory and standardisation fora not 

wholly related to spectrum management, 

• Monitoring and enforcement procedures and 

• Administrative functions including IT, Finance and Human Resources. 

It is reasonable for some or all of the above costs to be recovered by the licensing process, 

since without undertaking such functions the overall quality of the spectrum management 

activity may decline. Some administrations therefore include indirect as well as direct costs 

in the setting of annual administrative fees. 

7.2.9 Approaches to setting Spectrum Fees 

Cost-based spectrum fees are similar to administrative fees in that they are intended to 

recover the costs incurred by NRAs in the licensing and/or frequency management 

processes. However, unlike administrative fees, spectrum fees for individual licences take 

account of the type and/or amount of spectrum resource assigned to that licence. 

Typically they are set on a per-bandwidth basis, and may also take into account the 

frequency band. The costs that are to be recovered generally include both direct and 

indirect costs, though in most cases there is little or no information on how such charges 

are apportioned. Since there is not in practice a direct correlation between the amount and 

type of spectrum licensed and the costs incurred, cost-based spectrum charges may not 

reflect the costs associated with individual licences or authorisations, or even broad 

categories of licence or authorisation. 

7.2.10 Approaches to setting Spectrum Charges 


Like spectrum fees, spectrum charges are generally based on the amount or type of 

spectrum that is licensed. However, unlike spectrum fees, charges may be set at a level 

Page 265

that produces overall revenue in excess of the NRA’s cost, where this can be justified on 

the basis of ensuring optimal use of scarce spectrum resources. 

There are two main approaches to determining spectrum charges, namely administrative 

pricing and market-based mechanisms such as auctions. Administrative pricing can be 

used in conjunction with beauty contests, since the scarcity tends to limit the number of 

licences that can be offered; it may also be applied to services that are licensed on a first 

come first served basis, such as private CSR maritime services, to differentiate between 

congested and uncongested frequency bands or geographic areas. It should not be 

applied to spectrum that has been auctioned. 

The following sections provide a brief overview of administrative and market based 

spectrum pricing concepts. 

7.2.10.2 Administrative Pricing 

In instances where spectrum is congested (i.e. demand exceeds supply), administrative 

pricing offers an approach by which the value of the use of radio frequencies is taken into 

account and reflected in spectrum charges, thereby encouraging users who have an 

alternative to migrate to other technologies or frequencies. Under an administrative pricing 

regime spectrum charges tend to be set with reference either to the cost of the next best 

alternative technology or service, or to the level of profit that will be foregone if the user 

ceases to use the spectrum. The purpose of administrative pricing is to ration demand for 

spectrum in a way that promotes the economically efficient use of spectrum. The objective 

is far more than the recovery of costs. (See also Section 2.5) 

Administrative pricing may also be applied where there is no scarcity, by applying lower 

charges as an incentive (potentially below cost) to utilise frequency bands and/or locations 

that are not congested in order to encourage migration from congested bands or locations. 

A similar approach can be taken to providing incentives to introduce more spectrally 

efficient technologies. The term Administrative Incentive Pricing (AIP) is often used in this 

regard. 

Administrative pricing may be used both with "first come first served" and comparative 

(beauty contest) approaches to licensing. A "first come first served" approach is typically 

used for licensing of individual stations. Beauty contests have historically been the most 

common approach to awarding network licences where demand exceeds supply. 

7.2.10.3 Auctions 

Auctions are mentioned here for completeness. Essentially an auction involves the 

awarding of licences to those who bid the greatest amount in monetary terms. There are 

many varieties of auction and their design is a specialised skill. However, in all cases it is 

likely that certain pre-qualification criteria must be met to enable bidders to participate. 

These may be limited to simply demonstrating that the bidder has the financial resources 

to back up its bid, or may extend to meeting certain minimum service criteria or obligations 

should a licence be awarded. 

7.2.10.4 Hybrid approach 

A hybrid approach combines elements of both auctions and administrative pricing, for 

example by including a financial bid as one element of a beauty contest. 

7.2.10.5 NRA Objectives in setting fees and charges 

Part of the brief of this Study was to investigate countries' priorities in setting administrative 

fees and spectrum fees / charges. The questionnaire included a request to evaluate the 

relative importance of various parameters that might be taken into account in setting fees 

Page 266

and charges. The results for those countries that responded are presented in Table 7-6 

below. Since the responses by the administrations to the questionnaire were similar for all 

categories of aeronautical and maritime stations, whether satellite or terrestrial or installed 

on land or are mobile, the responses have been included in a single table. 

Spectrum Fees / Charges 

Promotion of spectrum efficiency 

Simplicity and transparency 

Recovery of costs 

Reflecting market value of 

spectrum 

Promotion of competition 

Geographical Coverage 

Raising revenue for Government 

Administrative Fees 

H 

K 

Promotion of spectrum efficiency 5 1 

TR UK 

Recovery of costs 5 1 2 

Simplicity and transparency 5 1 3 

Geographical Coverage 1 1 1 

Promotion of competition 1 1 

Raising revenue for Government 

Other 

Numbers of equipment 5 

Numbers of vehicles 5 

Correct registration of service 

users 

Key: 

1= not important, 2 = slightly important, 3 = average importance, 4 = very important, 5 = most important consideration 

Table 7-6 - Relative importance of various factors in setting fees and charges 

7.2.10.6 Secondary Trading 

As part of the study, administrations were asked whether they had any plans to introduce 

any form of spectrum trading, i.e. the ability of a licensed spectrum user to sell on all or 

part of his assigned spectrum to a third party. 

In Australia following a 1990 report by the Bureau of Transport and Communications 

Economics, which identified widespread inefficiency in many aspects of spectrum 

management in Australia and a 1991 report on the Management of the Radio Frequency 

Spectrum by the House of Representatives Standing Committee on Transport, 

Communications and Infrastructure, the Australian administration introduced the 

Radiocommunications Act 1992 to reform spectrum management. 

The Act introduced spectrum pricing and also provided for the creation of spectrum 

licences akin to property rights. The Act requires spectrum licences to be assigned by a 

market-based mechanism, such as an auction, tender or predetermined or negotiated 

price. There is a project instigated by the Australian administration with defined objectives 

for converting bands where practicable to spectrum licensing. However not all spectrum is 

considered by the Australian administration to be suitable for this, for example if there is a 

5 

Page 267

high degree of sharing or the band is subject to international co-ordination or is used for 

broadcasting. In such cases, apparatus licences, which permit the use of a particular 

technology and type of equipment, are being retained. These are also tradable. Both types 

of licence may be traded or sub-let but only spectrum licences can be sub-divided or 

aggregated. 

In New Zealand a tradable spectrum property rights scheme was adopted in late 1989 

following the enactment of the Radiocommunications Act 1989. A programme to convert 

portions of the spectrum from apparatus licensing to property rights followed. Apparatus 

licences are still being issued for most of the radio spectrum, including land mobile and 

fixed bands, but the New Zealand government aims to bring all fixed, mobile and 

broadcasting radio spectrum progressively under the new regime. 

The new system involves the creation of management rights and licence rights. 

Management rights do not confer the right to transmit but the manager is able to issue 

licences to itself or others for spectrum within its management. Holders of management 

rights pay no annual fee for those rights but will have paid through a tender process for the 

management right. They also have to pay a fee to the Ministry of Commerce (MoC) for any 

licence rights they issue to themselves and others. 

The new regime was applied first in broadcasting where the perceived need for reform was 

greatest. Spectrum trading is considered to be working well and, in combination with 

spectrum pricing, to have provided a degree of flexibility in spectrum utilisation that would 

not have occurred under a purely regulatory regime. 

In May 2003 the United States FCC changed the rules that prevented spectrum licensees 

from making available to others the temporary use of their spectrum. Subsequent to the 

2003 rule change companies were allowed to lease and trade spectrum licenses. The rule 

change was expected to create a secondary market for swapping licenses among various 

spectrum users, including broadcasters. However the primary beneficiary of the change 

was expected to be large mobile phone companies and broadcasters. Under the new rules 

the holder of a licence (with FCC approval) can allow another party to provide equipment 

and personnel to supplement his own activities. 

The UK is actively pursuing secondary trading with the 2003 Communications Act 

permitting the trading of spectrum rights. Spectrum trading is under consideration for 

possible implementation in the 2007 – 2009 timeframe for ground based aeronautical and 

coastal maritime communications. Additionally, a similar proposal is under consideration 

for ground based radiodetermination but is not proposed for on-board radio-determination 

equipment. In a number of EU Member States the matter is under active consideration. In 

Germany, a first draft of the new law has been presented for public discussion. In Austria, 

after a discussion process a new law was to be enacted before the summer of 2003. 

Despite the fact that all concepts have been based on the European framework there 

differences between the various countries. 

In response to the questionnaire Turkey indicated that it was contemplating the 

introduction of spectrum trading whilst Hong Kong had no plans to do so. 

In some countries licences are already transferable (subject to NRA or Government 

approval) which is itself a form of trading. Most European NRAs have no firm plans to 

introduce secondary trading, but do not object to its introduction in other Member States. 

If there is evidence of spectrum hoarding or inefficient reallocation of spectrum to highest 

value uses, the next issue is what means should and could NRAs use to prevent such 

hoarding, such as a use or lose requirement or some other mechanism. A major difficulty 

with use or lose is in the difficulty in defining "use", and the time that should be allowed 

before new services are developed. 

Page 268

7.2.11 ITU Notification 

Administrations were asked to provide information on how licence applications for 

aeronautical and maritime communications and radiodetermination stations were 

processed and notified to the ITU. In Hong Kong licensing information to be submitted to 

the ITU is sent via the Ministry of Information Industry of the People’s Republic of China. In 

the UK a similar procedure operates where necessary licensing information is obtained 

from the relevant databases; this is then forwarded to the ITU in the required format. 

Turkey responded by stating that ship station call signs and names were notified to the ITU 

list of ship stations periodically and radiodetermination stations were notified to the ITU list 

of radiodetermination and special services. 

7.3 Fees and Charges Information Provided 

7.3.1 Background 

This section of the Report analyses the specific situation in those countries that responded 

to the questionnaire. However as only 3 countries (Hong Kong, Turkey and the UK) had 

responded with detailed replies at the time of writing, information on actual fees and 

charges in other counties have been obtained from administrations’ public web sites. 

Part 2 of the questionnaire addressed general information concerning licensing and 

authorisations for radiocommunications stations used by the aeronautical and maritime 

sectors; the setting of fees and charges including the underlying national regulatory 

framework, and any planned developments that may lead to changes either to fee levels or 

to the licensing and regulatory regime. These issues were discussed in section 7.2 above. 

Parts 3 and 4 address the licensing requirements of communications applications for the 

aeronautical and maritime communities, as well as their passengers. Parts 5 and 6 

concern the licensing of radiodetermination applications used by the aeronautical and 

maritime sectors and include radar systems used for both navigational and nonnavigational 

purposes as well as navigational aids and other navigational systems which 

use spectrum but are not considered to use radar technology. 

Other Chapters in this report have addressed the ways in which more efficient radio 

technologies might be introduced to the aeronautical and maritime communities with 

respect to their communications and navigational needs. In addition socio-economic issues 

have also been addressed. 

It is clear that unlike more commercially orientated services one of the prime issues is the 

international nature of the services in question and that safety and operational integrity is 

of prime importance. In addition some of the applications and equipment are covered by 

European Directives where compliance with the requirements of the Directive can lead to a 

‘Mark’ which in turn can lead to the material being placed on the market or can be fitted on 

board aircraft and ships. Chapter 8 addresses the manner in which the goals of incentive 

administrative pricing can be achieved, whilst maintaining good order with European and 

global legal, regulatory, operational and standardisation requirements. 

7.3.2 Fees and Charges Overview 

Recipients of the questionnaire were asked to specify whether radio spectrum licences 

under study related to the spectrum itself, the use or installation of specific apparatus or a 

combination of the two. The responding countries indicated that for aeronautical and 

maritime services a combination of both applied. 

Some Member States apply administrative fees rather than spectrum fees or charges for 

the use of aeronautical and maritime radiodetermination and radiocommunications 

spectrum, i.e. the payment does not depend upon the amount or type of spectrum 

Page 269

esource consumed but is a flat fee per licence. This is justified on the grounds that unlike 

mobile or broadcasting spectrum, the spectrum under investigation has not historically 

been considered to be a scarce resource and is used for safety of life applications. 

However, growing demand for spectrum and a desire to operate a consistent 

administrative pricing policy has already led some countries to consider the adoption of 

spectrum charges based on administrative pricing techniques (see Section 7.2.10.2) to 

encourage more efficient and effective use of the spectrum. 

Table 7-7 indicates which countries are using, or planning to use administrative pricing, 

and the main parameters used in determining spectrum fees / charges for aeronautical and 

maritime services. Currently it is believed only Australia is applying administrative pricing 

for aeronautical and maritime services. The overall cost of an individual licence reflects the 

value and the amount of the spectrum being used (or denied to other users) by the 

licensee. This is calculated according to a formula that takes account of four parameters: 

• spectrum location; 

• geographic location; 

• bandwidth and 

• power. 

The formula means spectrum pricing is efficient, equitable and transparent, as fees reflect 

the amount of spectrum used, and are higher for spectrum in greater demand. For 

assigned licences, that is, where an individual frequency or frequencies are assigned, the 

tax is calculated individually for each licence. For non assigned licences, where each 

licence of the same licensing option has access to the same spectrum, the tax is the same 

for each licence. 

Table 7-8 shows the number of aeronautical and maritime licences issued in a number of 

countries which completed the questionnaire or provided the information by another 

means. Where available, the approximate revenue generated in administrative fees and 

spectrum fees / charges is also recorded. 

Table 7-9, Table 7-10, Table 7-11 and Table 7-12 below provide information on the 

detailed questions raised in the questionnaire concerning one-off and recurring 

administrative fees and spectrum charges. Most of the information has been obtained from 

the web pages of the administrations concerned. 

Administrative Pricing deployed Y N N N N 

Administrative Pricing planned N N N 

Frequency Band 

Amount of Spectrum (Bandwidth) Y 

Technology 

Spectrum Efficiency 

Geographic Location 

Transmitter Power 

Station Power EIRP 

Antenna Type 

Market Value of Spectrum 

Operator Financial Performance 

Frequency Co-ordination Y 

Licensing / authorisation costs Y Y 

A 

U 

N 

Z 

T 

R 

H 

K 

U 

K 

Page 270

Frequency Management Costs Y 

A 

U 

None Y 

Table 7-7: Approach to setting fees and charges for Aeronautical and 

Maritime Services 

No. of 

Aeronautic 

/Aircraft 

licences 

N 

Z 

Radiocommunications Radiodetermination 

Approx. 

annual 

revenue £ 

No. of 

Maritime 

coast/ship 

licences 

Approx. 

annual 

revenue £ 

T 

R 

H 

K 

No. of 

Aeronautic 

land/mobile 

licences 

U 

K 

Approx. 

annual 

revenue £ 

No of 

Maritime 

land/mobile 

licences 

Page 271 

Approx. 

annual 

revenue £ 

HK 44/155 4.7k/1.7k 196/1149 7.23k/14.4k NL 45.8/0 NL 109/645 

TR 0/1280 NIL 0/19684 NIL 189 NIL NIL NIL 

UK 1779/9207 950k 1463/65000 0/1,114,423 558/0 [3] 84/0 [4,5] 

AUS 2793 49k 3991/1353 62k/202k [6] 2145 181k 

[1]: NL = Not Licensed NIL=Question not answered 

[2]: Re Turkey aeronautical radionav figures do not include radar stations 

[3]: Re UK aeronautical radionav receipts included in overall aeronautical receipts 

[4]: Re UK maritime radionav figures refer to shore based navaids 

[5]: Re UK maritime radionav receipts included in overall maritime receipts 

[6]: Re Australia maritime radiodetermination figures and associated costs are a global figure for all 

radiodetermination applications. 

Table 7-8: Approximate number of licences and revenue generated by 

administrative fees and spectrum fees / charges in EU Member States (where 

provided by NRAs)

COUNTRY 

One-Off Administrative Fees applicable to: 

Australia 37 Issue Fee Assigned Licences 

Aeronautical £126.45 

Aircraft £52.91 

Q3.10 – Aeronautical Mobile Q4.10 – Maritime Mobile Q5.10 – Aeronautical Radionavigation 

& Radiolocation 

Issue Fee Assigned Licences 

Coast and Ship assigned £66 per 

hour of work involved 

Issue Fee 

Land £103.13 

Mobile available under aircraft licence 

Q6.10 – Maritime Radionavigation & 

Radiolocation 

Issue Fee 

Land £103.13 

Mobile available under ship licence 

Austria No English on Web Site No English on Web Site No English on Web Site No English on Web Site 

Bahamas None (i.e. nothing mentioned on 

their web site) 

None (i.e. nothing mentioned on 


None (i.e. nothing mentioned on their 

web site) 



Belgium No details found on Web Site No details found on Web Site No details found on Web Site No details found on Web Site 

Bermuda No details found on Web Site No details found on Web Site No details found on Web Site No details found on Web Site 

Brazil No English on Web Site No English on Web Site No English on Web Site No English on Web Site 

Canada Issuance Fee - Aeronautical 

Station fees £9.10/channel - 

Aircraft stations (domestic) 

exempt, (international) 

£9.10 

Issuance Fee - Coast Station fees 

£9.10/channel – Ship stations 

(domestic) exempt, (international) 

£9.10 

Issuance Fee - Land Station fees 

£9.92/channel – Mobile stations 


£9.92 

Issuance Fee - Land Station fees 

£9.92/channel - Mobile stations 


£9.92 

China No English on Web Site No English on Web Site No English on Web Site No English on Web Site 

Cyprus No details found on Web Site No details found on Web Site No details found on Web Site No details found on Web Site 

Denmark No details found on Web Site No details found on Web Site No details found on Web Site No details found on Web Site 

Finland No details found on Web Site No details found on Web Site No details found on Web Site No details found on Web Site 

France Law not signed – No charge 

levied for about 5 years 

Responsibility of French CAA no 

details on web site 

No charge in France No charge in France 

37 Many conditions apply – see http://www.aca.gov.au/aca_home/licensing/radcomm/licence_fees/overview.htm#Administrative%20charge 

Page 272

COUNTRY 


Germany Aeronautical Station £91 

Aircraft Station £91 



Coast Station £91 

Aircraft Station £91 

Land Station £91 

Mobile Station – Included in aircraft 

station fee 


Radiolocation 

Land Station £91 

Mobile Station £91 

Greece No details found on Web Site No details found on Web Site No details found on Web Site No details found on Web Site 

Hong Kong N/A N/A N/A N/A 

Ireland No details found on Web Site No details found on Web Site No details found on Web Site No details found on Web Site 

Italy No details found on Web Site No details found on Web Site No details found on Web Site No details found on Web Site 

Japan No details found on Web Site No details found on Web Site No details found on Web Site No details found on Web Site 

Korea No details found on Web Site No details found on Web Site No details found on Web Site No details found on Web Site 

Lebanon Initial Application £1.14 Initial Application £1.14 No details found on Web Site No details found on Web Site 

Liberia No Web Site/information No Web Site/information No Web Site/information No Web Site/information 

Luxembourg No English on Web Site No English on Web Site No English on Web Site No English on Web Site 

Malta No details found on Web Site No details found on Web Site No details found on Web Site No details found on Web Site 

Netherlands No details found on Web Site No details found on Web Site No details found on Web Site No details found on Web Site 

New Zealand 

Description: Ship or Aircraft. 

Amount Payable: £22.75 (£7.00 if application declined). 

Description: Mobile. 


Description: Coast. 


Description: Repeater. 


Norway One-time fees for registration of 

installed radio equipment in 

No details found on Web Site No details found on Web Site 

No details found on Web Site No details found on Web Site No details found on Web Site 

Page 273

COUNTRY 


Q3.10 – Aeronautical Mobile 

aircraft are: 

fully equipped aircraft of more 

than 9,000 kg, £400.00 

fully equipped aircraft of less than 

9,000 kg, £200.00 

aircraft that are not fully equipped, 

£80.00 

Q4.10 – Maritime Mobile Q5.10 – Aeronautical Radionavigation 



Radiolocation 

Pakistan Initial Approval Fee £41 Initial Approval Fee £41 No details found on Web Site No details found on Web Site 

Panama No English on Web Site No English on Web Site No English on Web Site No English on Web Site 

Portugal No details found on Web Site No details found on Web Site No details found on Web Site No details found on Web Site 

Russian Federation No details found on Web Site No details found on Web Site No details found on Web Site No details found on Web Site 

Singapore No details found on Web Site No details found on Web Site No details found on Web Site No details found on Web Site 

South Africa No details found on Web Site No details found on Web Site No details found on Web Site No details found on Web Site 

Spain No details found in English on 

Web Site 

No details found in English on 

Web Site 

No details found in English on Web 

Site 


Site 

Sweden No details found on Web Site No details found on Web Site No details found on Web Site No details found on Web Site 

Turkey Question not answered & no 

details found in English on Web 

Site 

Question not answered & no 


Site 

Question not answered & no details 

found in English on Web Site 



UAE No details found on Web Site No details found on Web Site No details found on Web Site No details found on Web Site 

UK N/A N/A N/A N/A 

USA N/A N/A N/A N/A 

COUNTRY Recurring Administrative Fees applicable to: 

Table 7-9 – One-off Administrative Fees 

Page 274

Australia Renewal fee £2.69 per assigned 

frequency per year 

For non-assigned aeronautical 

licence cost recovery fees £8.07 

per year per station 



Renewal fee £2.69 per assigned 


For non-assigned ship licence 

cost recovery fees £8.07 per year 

per station 




Radiolocation 




Bahamas 

Description: Aircraft Radio 

Telephone Operating Licence 

(Private Craft Restricted) 

Amount Payable: £16.80 annually 

Description: Aircraft Radio 

Telephone Operating Licence 

(Public Transport) 


Description: Ship Radiotelephone 

Station (Private Pleasure Craft) 

Amount Payable: £16.80 

annually 

Description: Ship Radiotelephone 

or Radio Telegraph Station on 

Cargo Freight or Working Vessel 

under Category A (vessels under 

400 gross tonnage). 


annually 

Description: Ship Radio 

Telegraph Station on Cargo 

Freight or Working Vessel under 

Category B (vessels over 400 

gross tonnage). 


annually 

Description: Operators – 

Radiotelephone Operating 

Licence Category A General 


annually 

Description: Aeronautical Fixed 

Ground Station Licence 


Description: Aircraft Radio Station 

Licence 



their web site 


Page 275

COUNTRY 

Recurring Administrative Fees applicable to: 




Radiolocation 



Canada Renewal Fee - Aeronautical Station 

fees £33.88/channel - Aircraft 

stations (domestic) exempt, 

(international) 

£29.76 

Renewal Fee - Coast Station 

fees £33.88/channel – Ship 

stations (domestic) exempt, 

(international) 

£29.76 

Renewal Fee - Land Station fees 

£33.88/channel – Mobile stations 


£33.88 

Renewal Fee - Land Station fees 

£33.88/channel - Mobile stations 


£33.88 





France Law not signed – No charge levied 

for about 5 years 

Germany Per year 

Aeronautical Station £175.70 

Aircraft Station £20.82 



Per year 

Coast station £6.82 

Ship station £6.82 


Per year 

Land station £175.70 

Mobile station – included in aircraft 

station fee 

Per year 

Land station £6.10 

Mobile station £6.10 


Hong Kong Description: Aircraft Station Licence 

fee (duration one year). 

Status: Recovery of administration 

costs for processing of application, 

maintenance of licence and 

spectrum management. 

Amount Payable: £10.50 per 

licence. 

Description: Ship Station Licence 

(duration one year). 

Purpose/basis: Recovery of 

administration costs for 

processing of application, 




licence. 

Description: 

Fee for Land Station (annual fee). 

Purpose/basis: Recovery of cost for 


Amount Payable: £4.20 per station. 

Description: Fee for mobile station 

(annual fee). 

Purpose/basis: Recovery of cost for 



station. 

Page 276

COUNTRY 




Description: Aeronautical VHF 

Fixed Station Licence fee 



administration costs for processing 

of application, maintenance of 

licence and spectrum management. 


licence, 

Ireland Description: Aircraft Radio Licence. 

Amount Payable: Not stated. 

Description: Pleasure Vessel 

Radio Network Station Licence 








licence. 

Description: PRS Licence (for 

services other than land mobile 

services). 






Amount Payable: 

£3500.00 per licence per annum. 

£70.00 per annum per land 

station or land earth station 

operated by the licensee. 

Description: Maritime Mobile 

Licence. 

Amount Payable: £2.52. 


Radiolocation 

Description: Fee for land station 

(annual fee). 

Purpose/Basis: Recovery of cost for 


Amount Payable: £5.60 per station. 



Page 277

COUNTRY 


Japan Description: Aircraft earth stations. 

Amount Payable: 

£22.00 annually per station. 



Description: Ship Stations. 


per station. 

Description: Static Coastal radio 

station. 


annually per station. 

Description: Ship earth stations. 


annually per station. 


Radiolocation 



Lebanon Annual Inspection £3.80 

Ship Station £3.80 

Coast Station £5.69 

>400W £9.48 

Inmarsat Station £57 

Annual Inspection £3.80 

Aircraft Station £3.80 

Aeronautical Station £5.69 

>400W £9.48 





Malta Description: Aeronautical Portable 

Transceiver On Board Aircraft 

Licence 


Description: Application for a 

Provisional Ship Radio Station 

Licence (Applicable Only to 

Ships complying with GMDSS 

Requirements) 


annually for vessels over 300 

tonnes & £47.10 for vessels 

under 300 Tonnes 


Page 278

COUNTRY 




Description: Application to install a 

Wireless Telegraphy Station For 

Air-Ground Communications 


Description: Application for the 

installation of a Wireless 

Telegraphy Station on Board Non 

GMDSS Sea Craft 

Amount Payable: No details 

found on Web Site 

Description: Application for a 

Private Maritime Mobile VHF 

Radio Station for use by Shipping 

Agents from their Offices with 

Ships 


found on Web Sit 

Description: Application for the 

use of VHF Sets on other boats 

of the Same Owner (applicable 

only to boats registered with the 

Fisheries Department) 


found on Web Site 


Radiolocation 


New Zealand 

Description: Ship or Aircraft. 

Amount Payable: £15.75 annually. 

Description: Mobile. 


Description: Coast. 


Description: Repeater. 



Page 279

COUNTRY 

Norway 




The annual fee is £28.00 for: 

a licence for radio equipment 

including communication services 

on board an aircraft 

a licence for radio navigation 

equipment on board an aircraft 

a licence for pulsed radar 

equipment on board an aircraft. 

The annual licence fee for a 

terminal on board an aircraft for 

telecommunication with a public or 

private network is £80.00 

The annual licence fee for radio 

equipment able to transfer 

data/speech by aero mobile, 

maritime and private channels on 

board an aircraft is £48.00. 

Pakistan Aircraft Station 

Type 1 £51 

Type 2 £71 

Type 3 £101 

Maritime Aircraft £51 

Aeronautical Station £71 

No details found on Web Site 

Ship station £51 

Coast station £101 


The annual fee for navigation systems 

is £80.00 for each base station and for 

use of: 

MF/HF frequencies, £400.00 

UHF frequencies, £160.00 

SHF frequencies, £80.00. 

The annual licence fee for an 

identifiable emergency positionindicating 

radio beacon on board an 

aircraft is £40.00 


Radiolocation 

The annual fee for navigation 

systems is £ 100.00 for each base 

station and for use of: 

MF/HF frequencies, £400.00 

UHF frequencies, £160.00 

SHF frequencies, £80.00. 







Page 280

COUNTRY 


Spain No details found in English on Web 

Site 




Web Site 


Site 


Radiolocation 


Site 


Turkey Question not answered & no details 




Site 






UK 

Description: Aircraft – 

Transportable (non fixed, hand 

held). 

Amount Payable: £15 renewal 

annually. 

Description: Aircraft Tier 3 

(includes: Gliders, etc). 


annually. 

Description: Aircraft Tier 2. 


annually. 

Description: Aircraft Tier 1. 


annually. 

Description: Ship Radio Licence. 


annually. 

Description: Ship Portable Radio 

Licence. 


annually. 

Description: Coastal Radio 

Station (CSR) Marina. 


annually (channels M, M2 & 80 

charges per base). 

Description: CSR International. 


annually (charged per base per 

frequency). 

Description: Navigational Aids (NDBs, 

DMEs, Beacons etc.). 


annually. 

Description: NAVAID/Radar. 


annually (charges per base per 

frequency). 

Description: DGPS VHF. 



frequency). 

Description: DGPS MF/HF. 

Amount Payable: £1,000 renewal 


frequency). 

Page 281

COUNTRY 




Description: Aeronautical (Ground 

to Air) Ground Stations (AGS) - 

General Aviation. 


annually. 

Description: AGS – Airfield Flight 

Information Service. 


annually. 

Description: AGS HF Licence. 


annually. 

Description: AGS – Air 

Traffic/Ground Movement Control. 


annually. 

Description: AGS – Operations 

Control (ex AGS Special). 


annually. 

USA Aeronautical Station £97.63 per 10 

years 

Domestic aircraft station exempt 

International aircraft station £55.79 

per 10 years 

Description: CSR UK. 



frequency). 

Description: CSR Training 

Establishment. 


annually. 

Description: Maritime Radio 

Suppliers Licence. 


annually. 

Coast Station £111.58 per 10 

years 

Domestic non GMDSS exempt 

International ship station £111.58 

Table 7-10 – Recurring Administrative Fees 


Radiolocation 

Covered by Aeronautical Licences Covered by Maritime licences 

Page 282

COUNTRY 

One-Off Spectrum Charges applicable to: 




Radiolocation 

Australia No one off charges No one off charges No one off charges No one off charges 


Bahamas None (i.e. nothing mentioned on 




None (i.e. nothing mentioned on their 

web site) 






Canada No Spectrum Charges No Spectrum Charges No Spectrum Charges No Spectrum Charges 





France Law not signed – No charge 

levied for about 5 years 




Germany No Spectrum Charges No Spectrum Charges No Spectrum Charges No Spectrum Charges 


Hong Kong Nil Nil Nil Nil 





Lebanon No details found on Web Site No details found on Web Site No details found on Web Site No details found on Web Site 


Page 283

COUNTRY 

One-Off Spectrum Charges applicable to: 




Radiolocation 




New Zealand Nil Nil Nil Nil 

Norway No details found on Web Site No details found on Web Site No details found on Web Site No details found on Web Site 

Pakistan No details found on Web Site No details found on Web Site No details found on Web Site No details found on Web Site 







Web Site 


Web Site 


Site 


Site 




Site 



Site 






UK Not Applicable Not Applicable Not Applicable Not Applicable 

USA Not Applicable Not Applicable Not Applicable Not Applicable 

Table 7-11 – One-Off Spectrum Charges 

Page 284

COUNTRY 

Recurring Spectrum Charges applicable to: 

Australia Aeronautical and aircraft 

assigned stations 

30MHz

COUNTRY 





Radiolocation 





Lebanon No details found on Web Site No details found on Web Site No details found on Web Site No details found on Web Site 





New Zealand 

Description: for other services (of which Aeronautical/Maritime might be) less than 10 dBW. 


Description: for other services (of which Aeronautical/Maritime might be) 10 dBW or more, but less than 20 dBW. 


Description: for other services (of which Aeronautical/Maritime might be) 20 dBW or more, but less than 30 dBW. 


Description: for other services (of which Aeronautical/Maritime might be) 30 dBW or more. 


Norway No details found on Web Site No details found on Web Site No details found on Web Site No details found on Web Site 

Pakistan No details found on Web Site No details found on Web Site No details found on Web Site No details found on Web Site 





Page 286

COUNTRY 





Radiolocation 

South Africa No details found on Web Site No details found on Web Sit e No details found on Web Site No details found on Web Site 


Web Site 


Web Site 


Site 


Site 




Site 



Site 






UK N/A N/A N/A N/A 

USA N/A N/A N/A N/A 

Table 7-12 – Recurring Spectrum Charges 

Page 287

7.4 Future Plans 

From the countries that returned the questionnaire the United Kingdom indicated that it 

was considering a change in the tariff structures for aeronautical and maritime licensing 

dependent on the outcome of this study. From the Consultant’s investigation of 

administrations’ web sites it was noted that the Australian Communications Authority (ACA) 

is currently conducting a review of the model used for calculating apparatus licence tax. 

The Australian Government has requested the ACA to investigate whether a more flexible 

and transparent model could be introduced. In particular whether all elements required for 

the calculation of fees could be provided to licensees. 

7.5 Identified Pricing Trends 

Unfortunately a limited number of detailed responses were received in the time available, 

however this information was supplemented by publicly available material and updating 

material collected some 2 years earlier as well as in-depth research and study of 

information available on the Internet. 

In general administrative pricing is not applied widely to aeronautical and maritime 

services. The only country where Administrative pricing seems to have been widely 

implemented is Australia. However even then Australia differentiates for aeronautical and 

maritime applications between those licensees who require an assignment and those that 

do not. Where an individual assignment is required the annual spectrum tax is calculated 

taking account of inter alia the bandwidth of the system. Furthermore, in some cases the 

amount of time taken to assign frequencies initially is calculated on an hourly rate. Where 

an apparatus uses unassigned frequencies a nominal fee is charged, which comprises an 

amount to cover costs and an element relating to the spectrum used. 

In some countries e.g. the US and Canada where aircraft and small vessels do not 

generally travel outside their national borders and are not subject to mandatory carriage 

requirements they are exempted from licensing. In the case of Canada and the US there is 

also a bilateral agreement with respect to the free movement of ‘small’ vessels and aircraft 

between the two countries. 

With respect to radiodetermination stations, mobile apparatus is often incorporated into the 

aircraft or ships licence at no extra charge. In the case of land radiodetermination stations 

the cost of licensing varies between zero as a result of minimal licensing requirements, for 

example if the systems are operated by governmental organisations, and a relatively high 

value such as found in Australia where the administrative pricing regime has introduced 

bandwidth and operational frequency factors into the pricing equation. 

In order to provide some overall comparisons between countries where prices have been 

found, the annual renewal costs for several types of station are portrayed in Table 7-13 

below. 


In view of the trend to deregulate licensing in some countries in the GA sector and 

domestic maritime non-SOLAS sector, it is recommended that a study should be 

conducted in the United Kingdom, possibly involving other British Isles administrations, of 

whether such an approach would benefit the UK aviation and maritime industries. Such a 

development might be restricted to the use of VHF aviation and maritime frequencies and 

on-board navigation apparatus. The introduction of a class licence for such applications 

could also be linked to AIP i.e. the use of spectrally efficient wireless telegraphy apparatus 

would meet the terms of the class licence, whilst continued use of ‘old’ equipment would 

continue to attract fees. However the need to record MMSI details would have to be 

addressed. See also section 6.6.10. Although it is envisaged such a scheme could be 

Page 288

limited to vessels registered by the flagging territories of the British Isles (two sovereign 

countries and three Crown dependencies), such a scheme might in future be proposed for 

extension to the European Union or CEPT. However the difficulties of attempting this are 

recognised. 

COUNTRY - 

Recurring Annual 

Cost for certain 

types of Station 

International 

Aircraft Station 

International 

Ship Station 

GMDSS 

Land 

Radionavigation 

Station (SHF radar) 

Australia £19.98 £19.98 £642 - £14,977 

Canada £29.76 £29.76 £33.88 

Germany £20.82 £6.82 £175.70 

Hong Kong £10.50 £10.50 £4.20 

Ireland £2.52. 

Japan £22 £6 

Lebanon £7.60 £7.60 

Malta £78.50 £78.50 

New Zealand £50.75 £50.75 

Norway £28 £80 

Pakistan £101 (max) £51 

UK £350 (max) £20 £50 

USA £5.79 £11.58 

Table 7-13 Comparative cost of annual apparatus/licence/station renewal charges 

The countries represented in Table 7-13 represent a broad spectrum of development with 

wide ranging GDPs. The United States appears to represent particularly good value for 

money for licensees; however the annual renewal fee is computed from a 10 year figure 

which is the usual period of validity for such licences in the United States. The effect of 

spectrum pricing can clearly be seen in the case of land based radar apparatus in 

Australia, with 9 GHz equipment representing the lowest cost and 3 GHz the highest cost. 

There appear to be no clear patterns concerning the level of fees and charges although in 

61% of the 13 countries listed aircraft station fees appear to be below £30 whilst 69% of 

ship station fees are less than £30, even an assumption that fees are generally intended to 

cover costs cannot easily be explained from the spread of values in Table 7-13. The UK 

fee for aircraft stations seems particularly high whilst Malta stands out as a country with 

high ship station licences. In principle, the Consultant is of the opinion that Administrative 

Incentive Pricing (AIP) should ideally be applied to all radiocommunication services, in 

order to encourage the efficient and effective use of spectrum. However in view of the 

international aspects of these systems including safety and operational considerations as 

well as single market and European issues, an innovative approach would be required to 

achieve such a development in Europe. This would be especially relevant for radar 

systems, however bandwidth tariff bands must be carefully considered in order to provide 

adequate incentives to reflect state of the art developments in technology. This matter is 

also addressed in Chapters 4 and 8 of this Report. 

Page 289

8 Summary of Report’s Conclusions and 

Recommendations 

8.1 Aeronautical Radiodetermination 

8.1.1 Primary radar 

Primary radar spectrum planning must take account of the continuing operational 

requirement for primary radar for en route, approach/TMA and airport surface detection. No 

fundamental changes have been identified in the operational requirement which would 

reduce spectrum requirements. The choice of technology utilised is driven primarily by the 

need to satisfy the operational requirement. Some increase in potential demand for civil 

ATC primary radar services, particularly for approach/TMA facilities and surface movement 

radar is expected. This demand is expected to grow in line with the general expansion in 

air transport and may be further influenced by security requirements. In addition there may 

a requirement for reduced false alarm rates which needs to be taken into consideration in 

the determination of radar protection criteria and band sharing opportunities. 



provide any incentive to move away from primary radar. A number of the specific detailed 

recommendations have already been implemented or planned by service providers. In 

particular, the use of solid state systems with pulse compression is becoming more widely 

adopted. 

Specific Measures identified to release spectrum included a consideration of the remaining 

primary radars in UHF broadcasting band v; the possibility of moving surface movement 

radars currently in Ku Band to X band and the continuing evaluation and development of 

alternative systems having the potential to release spectrum. 

General Improvements to the spectral characteristics of primary radar could include the 

development of a long term policy to replace magnetron transmitters. However in the 

shorter term, consideration could be given to equipping magnetron transmitters with low 

pass filters to meet the current emission mask. The current unwanted emission mask for 

radar transmitters should be adopted as the medium term goal for primary radar systems 

and it is considered that pulse compression should be the technology of choice for future 

primary radar systems for both operational requirements and spectrum efficiency reasons. 

However solid state transmitters should be adopted for future systems given the ability to 

control pulse rise and fall times to minimise out of band emissions. 

With respect to band sharing more visibility of spectrum used for defence purposes in the L 

and S bands may assist the delivery of improved spectrum efficiency and an initiative in 

this respect could be considered. However the most important issue with respect to 

spectrum sharing is for the development of a methodology which can assess the feasibility 

of various sharing scenarios. This would lead to a more strategic approach to the 

identification of band sharing opportunities. Studies into the use of a statistical approach to 

band sharing opportunities in a fully regulated environment should be continued and 

extended to include full consideration of operational and technical requirements of radar 

services. 

For the long term, R and D studies into the cost and benefits of using 3D radars in ATC 

applications should be considered. Operational validation and methods of funding should 

also be reviewed. 

It is believed that increased standardisation of primary radar characteristics should be 

considered as a means for improving spectral efficiency and increasing compatibility with 

Page 290

potential band sharing services. Improved spectrum utilisation characteristics should be a 

standardisation objective. Standardisation could be carried out by industry bodies such as 

EUROCAE for technical standards or by EUROCONTROL for operational standards. 

Global aspects would require the involvement of ICAO. It is considered that increased 

standardisation would achieve operational benefits as well as spectrum utilisation benefits. 

8.1.2 Secondary radar 

The two frequencies 1030 MHz and 1090 MHz are key to any consideration of secondary 

radar. The principal developments which will influence the use of these frequencies include 

the transfer to Mode S from current SSR and the implementation of ADS-B services using 

1090 MHz with a resulting possibility that congestion may occur. It is therefore necessary 

to ensure that the tailoring of SSR Pulse Repetition Frequencies conforms to ICAO 

recommendations. The implementation of Mode S SSR in the UK should be encouraged 

(allowing selective addressing and potentially fewer replies) coupled with the 

implementation of measures to encourage hardware roll out and the implementation of 

controller tools which use the resulting data. 

With respect to Mode S Extended Squitter implementation it has been proposed that 

Ofcom should work with the CAA in ensuring that data downlinked from the aircraft is not 

superfluous to requirements. In particular this would mean reviewing the need for regular 

broadcast of DAPs. 

The 1090MHz channel will be severely constrained in the medium term. A review of the 

future use of this band should be carried out. The review should ensure that any new 

applications meet clearly defined operational requirements; if not, studies should be 

performed to assess the potential benefit against the cost to an already saturated channel. 

The studies should also assess the timescales over which the applications will remain 

effective given that increase in traffic will further saturate the channel. Crucially, it should 

be ensured that introduction of new applications do not impact on existing safety of life 

applications such as SSR and ACAS. Other technologies for ADS-B should also be 

evaluated to ensure that spectrum efficient solutions are developed and implemented. In 

addition the possibility of further utilising 1030MHz (for example, for TIS-B) should be 

encouraged and studied. 

8.1.3 Aeronautical Radio-Navigation Services 

The timely decommissioning of aged radio navigation aids which become surplus to 

requirements has been identified as an issue, in particular, NDBs and VORs. However the 

operational requirements of the affected players and the capability of envisaged 

replacement systems must be assessed particularly from a safety and security viewpoint. 

Furthermore, in the interests of spectrum efficiency it may be opportune to conduct a study 

concerning the rationalisation of DME spectrum, in particular addressing the long-term 

spectrum requirements for DME. This would include an investigation into the feasibility and 

practical implications of de-pairing VOR, DME and ILS frequencies and de-tripling 

ILS/MLS/DME assignments. The possible effects of UAT (ADS-B datalink) on DME 

frequencies should also be studied. 

8.2 Maritime Radiodetermination 

A notable outcome of this study is the reaffirmation that the 5 GHz band is little used by 

(commercial) maritime radar in and around the UK. It is already shared with PMSE 

applications and HiperLAN. Further sharing of this spectrum with other suitably compatible 

services may be feasible and could be investigated. On the basis that some of the 

technological advances developed for aeronautical radar may find their way to the maritime 

sector a reduction in the allocations to maritime radar at 3, 5 and 9 GHz might be 

Page 291

considered, however such a reduction would require a study into congestion levels in the 

three bands. An additional option would be to consider the introduction of additional 

sharing, in particular with PMSE in the 3 and 9 GHz maritime bands. 

A survey into the usage of ship-berthing radar should be conducted and a suitable 

allocation (if available and required) made available to facilitate the licensing of such 

apparatus. 

8.3 Aeronautical Radiocommunications 

An urgent first measure is to promote the migration to 8.33 kHz spacing in the VHF band. 

This measure will alleviate the immediate shortage of VHF spectrum and facilitate the 

establishment of digital services. 



cover a wide geographic area. For low level implementation, the barrier is the GA sector 


The implementation of 8.33 kHz channel spacing needs to be encouraged, including the 

acceleration of necessary changes to the NATS infrastructure and considering the issue of, 

and a possible means of stimulating, GA equipage. 

Medium term measures include encouraging the aeronautical community to bring the 

demand for new voice channels under control through the introduction of more efficient air 

traffic control concepts such that the demand begins to level off, for example transferring 

existing ACARS data to VDL Mode 2 and freeing up VHF spectrum by decommissioning 

VORs. 

The introduction of VDL2 provides an opportunity to transfer existing ACARS traffic with a 

resultant increase in spectrum efficiency by a factor of 10. ATIS services should also be 

transferred making possible the re-allocation of some of the spectrum. It is proposed that 

new VDL services will occupy the spectrum between 136 and 137 MHz (i.e. that spectrum 

newly assigned to aeronautical communications). However this spectrum is already in use 

for analogue services which will have to be found new frequencies below 136 MHz. One of 

the problems with the band 136 to 137 MHz concerns harmonic radiation from ISM 

equipment operating in the 13 and 27 MHz ISM bands. This causes particular concerns for 

airborne receivers which have a very large radio line-of-sight. The decommissioning of 

VOR navaids would provide additional VHF spectrum for communications applications; 

however it is important to take action to agree timescales internationally for 

decommissioning this equipment. 

It is important to determine a strategy for the long term transfer to data. This includes 

establishing plans for a technology choice including the consideration of satellite based 

services as well as the use of the aeronautical VHF band and the resultant possible 

transfer of services. It has also been suggested that the possibility of investigating, in cooperation 

with the Ministry of Defence, whether the air-ground-air bands in the range 230 – 

380 MHz could for non secure communications be candidates for 8.33 kHz channel 

spacing, with a view to determining whether a reduction in air-ground-air bands could be 

considered, ideally within NATO Europe or as a minimum within the UK. 

8.4 Maritime Radiocommunications 

The use of radio based short range devices (SRDs) is increasingly a requirement on board 

ships. The ideal solution would utilise globally available ISM bands however if this does not 

meet all maritime requirements, the next best alternative would be to harmonise solutions 

capable of being implemented on a regional basis. 

Page 292

Very little use is made of the MF telegraphy band with the exception of 490 kHz, 500 kHz 

and 518 kHz; there is thus little traffic in the band 415-526.5 kHz. In several places within 

Chapter 6 the possibility for the introduction of new technology or a change of use has 

been postulated. The Consultant has postulated that the LF to HF frequency range 

addressed in this study would benefit from a European market and harmonised frequency 

bands to ease co-ordination difficulties and provide economies of scale for industry. A 

CEPT DSI process for the band 30 kHz to 30 MHz is suggested as a possible way to 

respond to such an approach. In addition to consulting widely, it is suggested that every 

opportunity should be sought for introducing the relevant technical, operational, economic 

and regulatory issues contained in this Report into the committee structure and decision 

making processes of the relevant international bodies. The overall objective should be to 

continue to promote innovation in the spectrum management process at the international 

level. 

Subject to the results of public consultation and any European DSI process new digital 

systems in the 2 MHz MF band might be considered on a national and non-interference 

basis taking account of the need to maintain interoperability with ships from foreign 

countries. 

Adaptive systems have been successfully introduced to the fixed service in the HF bands. 

They would likewise offer great advantages to the maritime mobile service in the MF and 

HF bands; the regulatory pre-conditions necessary might therefore be developed for the 

implementation of such techniques. 

In the HF bands, there is a rapidly growing need for digital technologies and the 

international community is engaged in the necessary studies. It is recommended that every 

effort is made to support these studies and refrain from implementing national solutions 

that might not be compatible with the outcome of these studies. 

At VHF, an in depth study of all UK applications within the ‘maritime band’ addressing the 

international maritime channels as well as Coast Station Radio private maritime channels 

should be considered. The principal goal would be to determine the future VHF spectrum 

requirements of the UK maritime industry with a view to the rationalisation of the current 

spectrum, taking account of recent changes in the industry and the introduction of new 

technologies. 

At UHF, the use of 12.5 kHz technology on all ten UHF on-board channels has been 

suggested in order to minimise possible interference in a mixed scenario. Turning to public 

correspondence, the GSM system at 900 MHz is increasingly used by the maritime 

community as a substitute for maritime VHF public correspondence. IMT-2000 is now 

being implemented and in the long term, it will likely replace GSM 900. The question of 

how frequencies at 900 MHz should be made available for the implementation of IMT-2000 

in coastal areas, when GSM is planned for decommission requires some consideration. 

The outcome of such strategic thinking might also have some impact on the policy adopted 

for the VHF bands. 

8.5 Licensing 

No clear trends resulted from the benchmarking part of the study; however it appears that 

only Australia has implemented administrative pricing in respect of aeronautical and 

maritime services. Even then pricing is only applied where specific frequencies are 

assigned, although a nominal amount is charged for non-assigned applications, which are 

not subject to the class licences applicable for domestic (non-SOLAS) ships and aircraft. 

It is suggested that a study should be conducted whether a class licence approach would 

benefit the UK aviation and maritime industries for access to VHF aviation and maritime 

frequencies and on-board navigation apparatus. A class licence for such applications could 

also be linked to AIP only applying fees and charges if older equipment continues to be 

Page 293

used. However the need to record MMSI details would have to be addressed. The 

extension of such a concept to the whole of the British Isles is also briefly discussed. 

8.6 General Issues and Recommendation 

This study brings together most of the key spectrum management issues. Previous 

chapters deal with frequency management and harmonisation of use, socio economic 

factors and the market, refarming of spectrum, the introduction of new technology, 

standards, licensing including fees and charges, administrative pricing, European and 

international regulatory issues, and the co-ordination of spectrum with neighbouring 

countries. 

The goal of any administration is to utilise the spectrum in an efficient and effective manner 

by creating a predictable environment for current and future use of radio in a manner which 

is in the public interest. The use of the radio spectrum needs to be strategically planned in 

order to create an environment which allows for the long term planning and harmonisation 

with international trends concerning radio services and products, whilst maximising the 

potential for users and industry. 

Objectives to be achieved may include the following: 

• To allow the development of new services to meet customer and governmental 

demand for radio services 

• To manage the radio spectrum taking account of governmental requirements and 

the needs of the various commercial sectors 

• To harmonise spectrum use with international developments (ITU, CEPT and the 

EU) 

• To enable liberalisation of, and competition for, telecommunications (including 

radiocommunications) services and equipment 

• To enable the realisation of public policy objectives on safety (including 

emergency services), cultural (including broadcasting) and social issues 

• To stimulate technological innovation and competitiveness 

• To support economic growth, create employment and to promote general welfare 

• To support national security and defence. 

In the case of the aeronautical and maritime sectors and the maximising of the spectrum 

resource available to them, the key issues would seem to be safety, market issues, the 

European regulatory framework, treaty obligations, standards, the introduction of new 

technology and last but not least the possible use of incentive pricing to realise spectrum 

efficiency gains within the two sectors. 

Let us take an example to explore the issue in detail. The UK has a need for additional 

PMSE spectrum and temporary long haul fixed service spectrum below 10 GHz. The 

current radionavigation bands at 3, 5 and 9 GHz seem possible candidates to fill this role. 

To achieve this scenario it would be necessary to consider a reduction in the size of the 

allocations concerned. 

8.6.1 Standards and the European Regulatory Framework 

The reduction in allocation to maritime radar in any of the currently used bands would have 

a direct impact upon the specifications of the radars deployed. Many current radars, though 

nominally operating on frequencies slightly offset from the centre of the bands, due to the 

short pulse-widths and the limitations in frequency control, in effect occupy the whole of the 

available band. However, technically there is no need for them to do so. The application of 

more modern techniques could reduce the overall bandwidth required. Such a change 

would therefore require radars sold in the UK to conform to a UK specific specification. UK 

vessels subject to IMO Carriage Requirements are required to comply with the EU Council 

Page 294

Directive on Marine Equipment, 98/85/EC and modifications. In accordance with the 

provisions of this Directive, radio equipment installed on board a vessel required to comply 

with SOLAS, must install equipment that complies with the standards of those 

Standardisation Bodies listed in the relevant Annex to the Directive. This requires that such 

equipment must comply with either the relevant ETSI Standard or the International Electro- 

Technical Commission (IEC) Standard. The equipment would also have to me marked as 

compliant with the standard. However Article 6.1 of the Directive states, ”No Member State 

shall prohibit the placing on the market or the placing on board a Community ship of 

equipment referred to in Annex A.1 which bears the mark or for other reasons complies 

with this Directive or refuse to issue or renew the safety certificates relating thereto.” 

These requirements would continue (unless the Directive and IMO Carriage Requirements 

were amended) even if the UK introduced a requirement for more spectrally efficient 

equipment to be installed on UK vessels since a vessel owner could still fit any equipment 

bearing the ships wheel mark. 

Of course safety is a major factor in the case of the IMO SOLAS Convention and a similar 

scenario exists in the case of aviation and the ICAO Convention. In this regard the 

operational requirements have been developed to ensure that the equipment provides an 

adequate level of operational integrity, designed to satisfy safety of life and property needs. 

A similar situation could arise with non SOLAS vessels where radar equipment is subject to 

the R&TTE Directive, 99/5/EC. This ‘new approach Directive’ relies on harmonised 

standards to provide a presumption of conformity with the essential requirements of the 

Directive, one of which (Article 3.2) requires the effective and efficient use of the radio 

spectrum to avoid harmful interference. In non harmonised frequency bands such as the 

radiodetermination bands, a manufacturer is required to notify an administration before 

placing the equipment on the market. Administrations in turn issue ‘interface requirements’ 

with any specific national requirements. It could be argued that if spectrally efficient 

requirements were introduced by the UK to avoid harmful interference to current and future 

services then this would be in accordance with the Directive. On the other hand difficulties 

might arise if UK requirements were such that CE marked or IEC compliant equipment 

designed for the band in question and accepted by other Member States were not 

acceptable in the UK. 

8.6.2 The Market 

Let us then assume that the UK would like to move forward in view of extreme pressures 

on the spectrum. Let us also assume that the standards issue can be resolved on the basis 

that European industry has realised the potential benefit of producing more spectrally 

efficient equipment which meets all the current standards. However, because the UK would 

be the only country adopting such an approach, the cost of the equipment would be 

significantly higher than conventional radar equipment which also carries the CE and 

‘Ship’s-Wheel’ marks. UK ship owners may well argue that in the case of SOLAS vessels 

they are entitled to fit the cheaper equipment, manufacturers may also challenge any UK 

‘national’ requirement, if it means their declaration of conformity is not accepted by a single 

Member State, in this case the UK. 

The Consultant therefore tends towards the opinion that any requirement for improvements 

in spectrum efficiency should be carried through to the European arena with a view to 

propagating UK requirements in the appropriate European forums. If successful the major 

European fleets of Cyprus, Malta and Greece, as well as other EU Member States would 

significantly increase the market size for more spectrally efficient equipment, producing 

significant economies of scale. 

Page 295

8.6.3 A Voluntary Approach 

The European regulatory framework no longer looks too kindly on a national approach to 

standards; thus the concept described below should be developed on a voluntary basis 

between the concerned parties, in this case Ofcom, the MCA, CAA and other stakeholders. 

The approach needs to be constructed in such a way that all parties feel they are gaining 

from the situation. 

For Ofcom the gains are obvious, additional spectrum resources to reallocate for other 

applications. In addition a stated goal of the voluntary activity could be to promote the 

‘voluntary’ standard in the appropriate standardisation bodies. For industry the advantages 

will be questioned. But if the UK was able to stimulate the European market and beyond, 

equipment sales would be significant. In the case of British and European industry, 

research and development activities to develop new technologies could also be stimulated. 

The companies might also be offered Ofcom support and influence in achieving the results 

of ‘voluntary’ discussions in the standards bodies. Turning to the owners, the purchase of 

equipment which met voluntary standards could be supported through AIP, in other words, 

once administrative pricing had been introduced a significant discount would accrue if 

bandwidth efficient equipment was installed within an agreed timetable. The major issue 

here is radar equipment. It is recognised that the current licence fees are rather low but it is 

assumed that AIP would be applied to non spectrally efficient equipment, which could 

increase the fees significantly. The voluntary scheme would then have the possibility of 

offering a discounted scale of tariffs. A condition of any class licence for domestic 

aeronautical and non SOLAS maritime traffic would be that the spectrally efficient 

equipment should be installed. If not then a standard licence and associated tariffs would 

be required. 

In summary a voluntary UK certification approach could be considered in parallel with the 

introduction of AIP to the aeronautical and maritime communities. This would still permit 

owners to purchase CE and Ship’s-wheel, marked equipment if they preferred that route. 

The UK interface requirement might include a ‘voluntary national measure’ where R&TTE 

and MED compliant equipment, which in addition utilised spectrally efficient technology, 

could receive favourable fees treatment under an AIP regime. 

The current UK interface requirement would be maintained but extended to include the 

voluntary category of equipment (for the R&TTE Directive) or a licence condition which met 

more strenuous spectral efficiency targets, thus attracting significant fee/charge discounts. 

Industry would have the benefit of developing a new generation of equipment with a 

subsequent increase in sales and likely mandatory carriage requirements in the future. 

Ofcom may gain spectrum but will need to promote the voluntary approach within Europe, 

as a first step towards the formal revision of a standard and/or the issue of a Commission 

mandate to the standards bodies. Of course in both SOLAS and non SOLAS cases, 

proportionality would be the key to achieving favourable treatment by the Commission and 

other Member States. It might also be advisable to discuss ‘voluntary national measures’ 

with the Commission before introducing such concepts. 


Ofcom is invited to consider the establishment of a voluntary regime to develop a UK 

certification process to stimulate the development of spectrally efficient techniques which 

may lead to improved spectrum occupancy and efficiencies. Such a process would need 

the support of both user and manufacturing communities. In addition it could be promoted 

as a European process as a means to signify when a particular standard or standards 

could be considered for revision. It is believed that such a process could benefit from the 

introduction of AIP to provide incentives to users to purchase new equipment. 

Page 296

8.6.4 Other AIP Issues 

In section 7.5 it was suggested that consideration might be given to the introduction of a 

class licence for domestic GA and non SOLAS ships, which did not travel outside the 

British Isles. The use of spectrally efficient VHF radio equipment for the safety and 

regularity of operations, as well as spectrally efficient on-board radionavigation applications 

could be a condition of such a class licence, see 8.6.3 above. If such a concept is 

favourably received it might be portrayed as an AIP approach, where the fees would be 

zero if voluntarily certified spectrally efficient equipment is deployed. If older equipment 

continues to be used, the official position could be that such equipment would attract a 

significant annual renewal charge, proportionate to the bandwidth used. 

For aeronautical and maritime mobile stations utilising frequencies generally available to 

these services, the introduction of an AIP regime is unlikely to have a major impact on fees 

and charges. This is borne out by the pricing structure introduced in Australia. 

Furthermore, in order to avoid a negative impact on the UK registry it may be appropriate 

to introduce a mechanism whereby the use of spectrally efficient mobile radionavigation 

equipment on domestic non SOLAS and GA vehicles is the subject of the class licence as 

described above. However continued use of radar equipment within a timetable to be 

agreed, not conforming to the state of the art voluntary standard would require individual 

licensing in accordance with AIP principles. 

On the other hand, land radionavigation systems might benefit from a more rigorous AIP 

approach in order to reflect the amount of spectrum occupied and the spectrum congestion 

likely in that geographical area. Costs should follow the typical AIP pattern described in 

section 2.5 above. With regard to radar systems the fee structures should ideally include 

appropriate tariff breaks which adequately award systems employing state of the art 

technology. 

Page 297

ANNEX 1 Glossary of Terms 

(OR) Off-Route 

(R) Route 

AAC Airline Administrative Control 

ACARS Aircraft Communications and Address Reporting System 

ACAS Airborne Collision Avoidance System 

ADAP Automatic Downlinking of Aircraft Parameters 

ADF Automated Direction Finder 

ADS Automated Dependence Surveillance 

ADS-B Automated Dependence Surveillance-Broadcast 

AEEC Airlines Electronic Engineering Committee 

AES (1) Aeronautical Enroute Service 

AES (2) Aircraft Earth Station 

AIC Aeronautical Information Circular 

AIP (1) Aeronautical Information Publication 

AIP (2) Administrative Incentive Pricing 

AIS Automatic Identification System 

ALOHA “Hello and welcome” (random-access protocol) 

AM Amplitude Modulation 

AMASS Airport Movement Area Safety System 

AMCP Aeronautical Mobile Communications Panel 

AMS Aeronautical Mobile Service 

AMSS Aeronautical Mobile Satellite Service 

AMTS Automated Maritime Telecommunication System 

ANM Aids to Navigation Management 

ANS Air Navigation System 

ANSP Aviation Navigation Satellite Programs 

AOA ACARS Over AVLC 

AOC Airline Operational Communications 

APC Aeronautical Public Correspondence 

APCO Association of Public-Safety Communications 

ARINC Aeronautical Radio Incorporated 

ARNS Aeronautical Radionavigation Service 

ASAS Airborne Separation Assurance Systems 

ASDE Airport Surface Detection Equipment 

Page 298

ASF Additional Secondary Factor 

ATC Air Traffic Control 

ATIS Automated Terminal Information Services 

ATM Air Traffic Management 

ATN Aeronautical Telecommunication Network 

ATS Air Traffic Services 

ATSIN Air Traffic Services Information Notices 

ATSOM Air Traffic Services Operations Memorandum 

ATSU Air Traffic Services Unit 

AVLC Aviation Link Control 

Bd Baud 

BDS Binary Data Store 

BPSK Bi-phase Shift Keying 

CAA Civil Aviation Authority 

CAA(DAP) Civil Aviation Authority (Directorate of Airspace Policy) 

CAASD Center for Advanced Aviation System Development (in USA) 

CAP Controller Access Parameter 

CB Citizens Band 

CDI Course Deviation Indicator 

CDMA Code Division Multiple Access 

CDTI Cockpit Displays of Traffic Information 

CEN European Committee for Standardization 

CENELEC European Committee for Electrotechnical Standardization 

CEPT European Conference of Postal and Telecommunications administrations 

CFAR Constant False Alarm Rate 

CISPR International Special Committee on Radio Interference 

CLOVER 

CLT Radio Luxembourg 

The generic name of a class of modulation waveforms that use sequential 

amplitude-shaped tone pulses to send data. The modulation may be forms 

or combinations of frequency, phase, or amplitude shift modulation of a 

tone pulse. 

CNS Communications, Navigation and Surveillance 

COM Communications 

COMSAR Search and Rescue Committee (of IMO) 

COSPAS-SARSAT International Satellite System for Search and Rescue 

CPDLC Controller Pilot Datalink Communications 

CRC Cyclic Redundancy Check 

CSC Common Signal Channel 

CSMA Carrier Sense Multiple Access 

Page 299

CSR Coast Station Radio 

D8PSK Differential 8-ary Phase Shift Keying 

DAP Downlink Airborne Parameters 

dB Decibel 

DECT Digital Enhanced Cordless Telecommunications 

DEFRA Department for Environment, Food & Rural Affairs 

DF Direction Finding 

DGNSS Differential Global Navigation Satellite Systems 

DGPS Differential Global Positioning System 

DME Distance Measuring Equipment 

DOS Directory of Services 

DfT Department for Transport 

DPSK Differential Phase Shifting Keying 

DRM Digital Radio Mondiale 

DSB Double Side Band 

DSC Digital Selective Calling 

DSI Detailed Spectrum Investigation 

DSP Digital Signal Processing 

DSSS Direct Sequence Spread Spectrum 

DTI Department of Trade and Industry 

DVOR Doppler Very High Frequency Omnidirectional Range 

EC (1) European Commission 

EC (2) Executive Controller (Radar Controller) 

ECAC European Civil Aviation Conference 

ECC Electronic Communications Committee 

ECDIS Electronic Chart Display and Information Systems 

EGNOS European Geostationary Navigation Overlay Service 

EIRP Effective Isotropic Radiated Power 

ELT Emergency Locator Transmitter 

EMA European Maritime Area 

EMC Electromagnetic Compatibility 

ENG/OB Electronic News Gathering (Outside Broadcast) 

EPFD Equivalent Power Flux Density 

EPIRB Emergency Position Indicating Radio Beacon 

ERO European Radiocommunications Office of CEPT 

ESA European Space Agency 

ESV Earth Stations on Vessels 

Page 300

ETRA Environment, Transport and Regional Affairs Committee 

ETSI European Telecommunications Standards Institute 

EU European Union 

EUROCAE European Organisation for Civil Aviation Equipment 

EUROCONTROL European Organisation for the Safety of Air Navigation 

FAA Federal Aviation Administration 

FATDMA Fixed Access Time Division Multiple Access 

FCC Federal Communications Commission of the USA 

FDD Frequency Division Duplex 

FEC Forward Error Correction 

FHSS Frequency Hopping Spread Spectrum 

FM Frequency Modulation 

FM WG Frequency Management Working Group (of CEPT) 

FMS Flight Management System 

FRUIT False Replies Unsynchronised In Time 

FSK Frequency Shift Keying 

FSS Fixed Satellite Service 

GA General Aviation 

GBAS Ground-Based Augmentation Systems 

GDP Gross Domestic Product 

GES Ground Earth Station 

GFSK Gaussian Frequency Shift Keying 

GHz Gigahertz 

GICB 

Ground Initiated “Comm B” – (note that “Comm B” is a specific protocol 

used by Mode S SSR) 

GLA General Lighthouse Authorities 

GLONASS Global Orbiting Navigation Satellite System 

GLS GPS Landing System 

GMDSS Global Maritime Distress and Safety System 

GMSK Gaussian Minimum Shift Keying 

GNSS Global Navigation Satellite System 

GPS Global Positioning System 

GPWS Global Proximity Warning System 

GSC Global Signalling Channel 

GSM Global System for Mobile communications 

HF High Frequency (3 MHz – 30 MHz) 

HFDL HF Data Link 

I2S Integrated Information System 

Page 301

IALA 

International Association of Marine Aids to Navigation and Lighthouse 

Authorities 

IARU International Amateur Radio Union 

IATA International Air Transport Association 

ICAO International Civil Aviation Organisation 

IEC International Electrotechnical Commission 

IEEE Institute of Electrical and Electronic Engineers 

IFE In-Flight Entertainment 

IFF Interrogate Friend or Foe 

IFR Instrument Flight Rules 

ILS Instrument Landing System 

IMO International Maritime Organization 

IMT International Mobile Telecommunications 

IMT 2000 

International Mobile Telecommunications (global standard for third 

generation (3G) wireless communications) 

INS Inertial Navigation System 

IP Internet Protocol 

IPR Intellectual Property Rights 

IRS Inertial Reference System 

ISM Industrial, Scientific or Medical 

ITT International Telephone and Telegraph 

ITU International Telecommunication Union 

JTIDS Joint Tactical Information Distribution System 

kHz KiloHertz 

LAAS Local Area Augmentation System 

LAN Local Area Network 

LEO Low Earth Orbit 

LF Low Frequency (30 kHz – 300 kHz) 

LNA Low Noise Amplifier 

LOM Locator Outer Marker 

LOP Line-Of-Position 

LORAN Long Range Navigation 

LSC Local Signalling Channels 

MASPS Minimum Aviation Systems Performance Specification (or Standard) 

MATS Manual of Air Traffic Services 

MCA Maritime and Coastguard Agency 

MED Marine Equipment Directive 

MEO Medium Earth Orbit 

Page 302

MF Medium Frequency (300 kHz – 3000 kHz) 

MHz MegaHertz 

MIDS Multifunction Information Distribution System 

MITRE A registered trademark of the MITRE Corporation 

MLS Microwave Landing System 

MMR Multi-Mode Receiver 

MMSI Maritime Mobile Service Identity 

MNP Marine Navigation Plan 

MoD Ministry of Defence 

MOPS Minimum Operational Performance Specification 

M-PSK M-ary Phase Shift Keying 

MRNS Maritime Radionavigation Service 

MSI Maritime Safety Information 

MSK Minimum Shift Keying 

MSO Message Start Opportunities 

MSP Mode S Specific Protocol 

MSS Mobile Satellite Service 

MSSR Monopulse Secondary Surveillance Radar 

NAS National Airspace System 

NATO North Atlantic Treaty Organisation 

NATS National Air Traffic Services 

NAV Navigation 

NAVTEX Navigational Text 

NBDP Narrow Band Direct Printing 

NBPSK Narrow Band Phase Shift Keying 

NCS Network Coordination Stations 

NDB Non-Directional Beacon 

NELS Northwest European Loran-C System 

NEXCOM Next Generation Air/Ground Communications 

NGSS Next Generation Satellite System 

nm Nautical Mile 

NOC Network Operations Centre 

NPA Non-Precision Approach 

NPV Non-Precision approach operations with Vertical guidance 

NRA National Regulatory Authority 

NVIS Near Vertical Incidence Sky-wave 

ODIAC Operational Development of Initial A/G Data Communications 

Page 303

Ofcom UK Office of Communications 

OoB Out of Band 

PA Precision Approach 

PAR Precision Approach Radar 

PBR Private Business Radio 

PC Provisional Council 

PCS Personal Communications System 

PFD Power Flux Density 

PMSE Programme Making and Special Events 

P-NAV Precision Area Navigation 

POP3 Post Office Protocol No 3 

PPM Pulse Position Modulation 

PRF Pulse Repetition Frequency 

PS Polling Service 

PSK Phase Shift Keying 

PSR Primary Surveillance Radar 

QPSK Quadrature Phase Shift Keying 

R&D Research and Development 

R&TTE Radio and Telecommunications Terminal Equipment 

RA WG Regulatory Affairs Working Group (of CEPT) 

RAAS Regional Area Augmentation System 

RACON Radar Beacons 

RAF Royal Air Force 

RCS Radar Cross Section 

RES Radio Equipment and Systems 

RF Radio Frequency 

RICE Remote Interface Control Equipment 

RNAV aRea NAVigation 

RNLI Royal National Lifeboat Institution 

RNP Required Navigation Performance 

RPM Revenue Passenger Miles 

RR Radio Regulations (of the ITU) 

RSC Regional Signalling Channel(s) 

RSGB Radio Society of Great Britain 

RSIM Reference Stations and Integrity Monitors 

RTCA Radio Technical Commission for Aeronautics 

RTCE Real Time Channel Evaluation 

Page 304

RTCM Radio Technical Commission for Maritime Services 

RTE (1) Radar Target Enhancers 

RTE (2) Radio Telefis Eireann 

RVR Runway Visual Range 

SA Selective Availability 

SAR Search and Rescue 

SARPS Standards and Recommended Practices 

SART Search and Rescue Transponder 

SATCOM Satellite Communication 

SDLS Satellite Data Link Service 

SDM System Definition Manual 

SE WG Spectrum Engineering Working Group (of CEPT) 

SICASP 

Secondary Surveillance Radar Improvements and Collision Avoidance 

Systems Panel 

SIEM Mode S extended squitter simulation model operated by Qinetiq. 

SITA 

Provider of global information and telecommunication solutions to the air 

transport and related industries. 

SITOR Simplex Telex Over Radio 

SMA Spectrum Management Activities (in EUROCONTROL) 

SNDCF Sub-Network Dependent Convergence Function 

SNR Signal to Noise Ratio 

SOLAS Safety of Life at Seas 

SOTDMA Self-Organised Time Division Multiple Access 38 

SPI Special Position Indicator 

SRD Short Range Devices 

SRE Surveillance Radar Element 

SSB Single Sideband 

SSR Secondary Surveillance Radar 

STDMA Self-organising time division multiple access 

TACAN Tactical Air Navigation 

TDD Time Division Duplex 

TDMA Time Division Multiple Access 

TETRA Terrestrial Trunked Radio 

TFTS Terrestrial Flight Telephone System 

38 By convention, “SODTMA” is used in the Maritime community for self-organising TDMA 

whereas “STDMA” is used by the Aeronautical community 

Page 305

TIS-B Traffic Information Services – Broadcast 

TMA Terminal Manoeuvring Area 

TOA Time Of Arrival 

TOR Telex Over Radio 

TRSB Time Reference Scanning Beam 

TWT Travelling Wave Tube 

UAT Universal Access Transceiver 

UAV Unmanned Airborne Vehicle 

UHF Ultra High Frequency (300-3000 MHz) 

UK United Kingdom 

UMTS Universal Mobile Telecommunications System 

UN United Nations 

URL Uniform Resource Locator 

UTC Universal Time Co-ordinates 

UWB Ultra-Wide Band 

VDL VHF Data Link 

VDR VHF Data Radio 

VFR Visual Flight Rules 

VHF Very High Frequency (30 to 300 MHz) 

VOLPE FAA, John A. Volpe National Transportation Systems Center (in USA) 

VOR Very High Frequency Omnidirectional Range 

VSWR Voltage Standing Wave Radio 

VTS Vessel Traffic Services 

WAAS Wide Area Augmentation System 

WCDMA Wide-band CDMA 

WLAN Wireless Local Area Network 

WRC World Radiocommunication Conference 

Page 306

ANNEX 2 Mandatory Standards 

Annex 2-1 Aeronautical Radiodetermination Standards 

Band 130-535 kHz (selected bands) 

Service Aeronautical radionavigation 

Aviation use 

Annex 10 

Non-directional beacons, locator beacons 

SARPs Annex 10, Volume I, Chapter 3, paragraphs 3.4 and 3.9 

Frequency plan Regional plan 

Channelisation 1 kHz spacing; in EUR Region 0.5 kHz assignments may also 

be used. 

Planning criteria 

Annex 10, Volume V, Chapter 3, paragraph 3.2 

Annex 10, Volume I, Attachment C, paragraph 6 

Annex 10, Volume V, Attachment B 

Air Navigation Plan European Area Regional Plan, Part X, Table COM-4 

Other regions to be added 

RTCA MOPS DO-179; MOPS for ADF equipment (1982) 

Eurocae MOPS 712-7 

ARINC characteristic ED-51 

ITU Res./Rec./Reg. None 

Other material CCIR Report No. 910-1 - Sharing between the maritime mobile 

service and the aeronautical radionavigation service in the band 

415-526.5 kHz. Note.-This report is published in Annex 3 to 

Volume VIII of the Report of the XVII Plenary Assembly of the 

International Radio Consultative Committee (CCIR) (Düsseldorf, 

1990). 

Final Acts of the Regional Administrative Conference for the 

Planning of the MF Maritime Mobile and Aeronautical 

Radionavigation Service (Region l), Geneva 1985. 

Band 1800-2000 kHz (Region 3) 

Service Radionavigation 

Aviation use LORAN A 

Annex 10 

SARPs None 

Frequency plan None 

Channelisation Two frequencies - 1850 kHz and 1950 kHz 

Planning criteria None 

RTCA MOPS DO-194 MOPS for airborne area navigation equipment using 

LORAN-C (1986) 

Eurocae MOPS None 

ARINC characteristic None 


Other material None 

Page 307

Band 74.8-75.2 MHz 


Aviation use Marker beacon 

Annex 10 

SARPs Annex 10, Volume I, Chapter 3, 3.1.7 and 3.6 

Frequency plan Fixed frequency of 75 MHz 

Channelisation None 

Planning criteria Annex 10, Volume I, Attachment C, Section 5 

RTCA MOPS DO-143 MOPS for airborne radio marker receiving equipment 

operating on 75 MHz (1970). 

EUROCAE MOPS l/W67/70 




Band 108-117.975 MHz 


Aviation use 

Annex 10 

VOR (108-117.975 MHz ), ILS localizer (108-111.975 MHz ) 

SARPs Annex 10, Volume I, Chapter 3, 3.1 (ILS) and 3.3 (VOR) 

Frequency plan Annex 10, Volume I, Chapter 3, 3.1.6 (ILS) 

Channelisation 100 kHz/50 kHz spacing 


Annex 10, Volume V, Chapter 4, 4.2 

RTCA MOPS 

Eurocae MOPS 

ARINC characteristic 

ITU Res./Rec./Reg. 

Other material 

Annex 10, Volume I, Attachment C, 2.6 (ILS) 

Annex 10, Volume I, Attachment C, 3.5 (VOR/ILS) 

ILS: DO-195, MOPS for airborne ILS localizer receiving 

equipment operating within the radio frequency range of 108-112 

MHz. 

VOR: DO-196 MOPS for airborne VOR receiving equipment 

operating within the radio frequency range of 108-117.95 MHz. 

ILS: ED-46B, ED-74 (combined ILS/MLS) 

VOR: ED-22B, ED-52 (ground equipment) 

ILS: 710-9 

VOR: 711-9 

ITU-R M.441-1: Signal-to-interference ratios and minimum field 

strengths required in the aeronautical-mobile (route) service 

above 30 MHz 

ITU-R SM.1009: Compatibility between the sound broadcasting 

service in the baud 87-108 MHz and the aeronautical services in 

the band 108-137 MHz 

Receiver susceptibility to FM broadcast: 

• DO 176: FM broadcast interference related to airborne 

ILS, VOR and VHF communications (1981) 

• Annex 10, Volume I, Chapter 3, 3.1.4 (ILS) 

• Annex 10, Volume I, Attachment C, 2.2.10 (ILS) 

• Annex 10, Volume I, Chapter 3, 3.3.8 (VOR) 

• Annex 10, Volume I, Attachment C, 3.6.5 (VOR) 

DO-217 MASPS for DGNSS instrument approach system: 

Special Category 1 (SCAT-1) (1993) 

Change 1 to DO-217 (1994), change 2 to DO-217 (1990) 

Page 308

Band 328.6-335.4 MHz 


Aviation use ILS glide path 

Annex 10 

SARPs Annex 10, Volume I, Chapter 3, 3.1.5 

Frequency plan Annex 10, Volume I, Chapter 3, 3.1.6 

Channelisation 300 kHz or 150 kHz spacing 

Planning criteria as for ILS localizer 

RTCA MOPS DO-192, MOPS for airborne ILS glide slope receiving equipment 

operating within the radio frequency range of 328.6-335.4 MHz 

(1986) 

EUROCAE MOPS None 

ARINC characteristic 551 



Band 960-1215 MHz 


Aviation use DME 

Annex 10 

SARPs Volume I, Chapter 3, 3.5 

Frequency plan Volume I, Chapter 3, Table A. Volume V, Chapter 4, 4.3 

Planning criteria Volume I, Attachment C, Section 7 EUR ANP COM/3 

RTCA MOPS DO 189, MOPS for airborne DME operations within the 

frequency range of 960-1215 MHz (1995). 


ARINC characteristic 709, 709A (DMEYP) 

ITU Res./Rec./Reg. The use of the band 1 164-1 300 MHz by systems and networks 

in the radionavigation-satellite service for which complete 

coordination or notification information, as appropriate, is 

received by the ITU Radiocommunication Bureau after 

1 January 2005 is subject to the application of the provisions of 

Nos. 9.12, 9.12A and 9.13. Resolution 610 (WRC-03) shall also 

apply 


Band 1030 MHz and 1090 MHz 


Aviation use 

Annex 10 

SSR/ACAS 

SARPs Annex 10, Volume IV, Chapters 3 and 4 

Frequency plan Two frequencies: 1030 MHz for ground-to-air interrogations and 

1090 MHz for air-to-ground reply. 

Channelisation N/A 

Planning criteria Coordination of the pulse repetition frequency (PRF) on a 

national basis is required for overlapping coverage areas of 

SSR. 

RTCA MOPS 

DO 181C (Mode S) 

DO 185, MOPS for traffic alert and collision avoidance systems; 

airborne equipment consolidated edition (1983/ 1990) 

DO-218B MOPS for the Mode S airborne data link processor 

EUROCAE MOPS 718 (Mode S transponder and ACAS) 


ITU Res./Rec./Reg. Res. No. 18 (Mob-83): Relating to the procedure for identifying 

and announcing the position of ships and aircraft of States not 

parties to an armed conflict 

Page 309

Other material DO-197A MOPS for active traffic alert and collision avoidance 

system 1 (active TCAS 1) (1994) 

Band 1260-1400 MHz 

Service Radiolocation / Aeronautical radionavigation / Radionavigationsatellite 

Aviation use Medium- and long-range surveillance radar 

Annex 10 

SARPs None 

Frequency plan Nationally produced 

Channelisation Nationally produced 

Planning criteria Nationally produced 

RTCA MOPS None 



ITU Res./Rec./Reg. Rec. No. 701: Relating to the use of frequency band 1330-1400 

MHz by the radio astronomy service 

Res. No. 606 (WRC-2000): Use of the frequency band 1215- 

1300 MHz by systems of the radionavigation-satellite service 

(space-to-Earth) 

Res. No. 607 (WRC-2000): Studies on compatibility between 

stations of the radionavigaiton-satellite service (Earth-to-space) 

and the radiolocation service operating in the frequency band 

1300-1350 MHz 

ITU-R M.1463: Characteristics of and protection criteria for 

radars operating in the radiodetermination service in the 

frequency band 1215-1400 MHz 


Page 310

Band 1559-1626.5 MHz 

Service Radionavigation-satellite / aeronautical radionavigation 

Aviation use GNSS 

Annex 10 

SARPs Annex 10, Volume I, Chapters 2 and 3 

Frequency plan GPS; GLONASS 



RTCA MOPS 

DO-208; MOPS for airborne supplemental navigation equipment 

using GPS (1991) 

DO-228; MOPS for GNSS airborne antenna equipment (1995) 


ARINC characteristic 743 (GPS), 743A (GPVGLONASS) 

ITU Res./Rec./Reg. Resolution 220 (WRC-97): Studies to consider the feasibility of 

using a portion of the band 1559-1610 MHz by the mobilesatellite 

service (space-to-Earth) 

ITU-R M.823: Technical characteristics for differential 

transmissions for GNSS from maritime radio beacons in the 

frequency band 283.6-315 MHz in Region 1 and 285-325 MHz in 

Regions 2 and 3 

ITU-R M.1088: Considerations for sharing with systems of other 

services operating in the bands allocated to the radionavigationsatellite 

service 

ITU-R M.1317: Considerations for sharing between systems of 

other services operating in bands allocated to the 

radionavigation-satellite service and aeronautical 

radionavigation services and the global navigation satellite 

system GLONASS 

ITU-R M.1318: Interference protection evaluation model for the 

radionavigation-satellite service in the 1559-1610 MHz band 

ITU-R M.1343: Essential technical requirements of mobile earth 

stations 1-3 GHz 

ITU-R M.1477: Technical and performance characteristics of 

current and planned radionavigation-satellite service (space-to- 

Earth) and aeronautical radionavigation service receivers to be 

considered in interference studies in the hand 1559-1610 MHz 

ITU-R M.1480: Essential technical requirements of land mobile 

earth stations for global GSO MSS systems providing voice 

and/or data communications in the bands 1-3 GHz 

Other material GNSS Panel Reports 

RTCA DO-235 Assessment of Radio Frequency Interference 

Relevant to GNSS (1997). 

Page 311

Band 2700 - 3300 MHz 

Service Aeronautical radionavigation / Radionavigation 

Aviation use Primary surveillance radar, surveillance radar element (SRE) of 

precision approach radar (PAR) medium-range systems, 

ground-based weather radar. 

Annex 10 

SARPs Annex 10, Volume I, paragraph 3.2.4 






ITU Res./Rec./Reg. ITU-R M.629: Use for the RN service of the frequency bands 

2900-3100 MHz, 5470-5650 MHz, 9200-9300 MHz, 9300-9500 

MHz and 9500-9800 MHz 

ITU-R M.1460: Technical and operational characteristics and 

protection criteria of radiodetermination and meteorological 

radars in the 2900-3100 MHz band 

ITU-R M.1461: Procedures for determining the potential for 

interference between radars operating in the radiodetermination 

service and systems in other services 


radio-navigation and meteorological radars operating in the 



radars operating in the radiodetermination service in the 



Band 4200-4400 MHz 


Aviation use 

Annex 10 

Radio altimeters 

SARPs None 



RTCA MOPS 

DO-155 (Airborne low range radar altimeters (1974)) 

DO-161A (Airborne ground proximity warning system (1976)) 


ARINC characteristic 594 (GPWS), 707 

ITU Res./Rec./Reg. Rec. No. 606 (Mob-87): The possibility of reducing the band 

4200-4400 MHz used by radio altimeters in the aeronautical 

radionavigation service 

Report [BL/8] (Dusseldorf 1990) 

Question 94/8: Bandwidth required for radio altimeter 


Page 312

Band 5000-5250 MHz 


Aviation use 

Annex 10 

MLS 

SARPs Annex 10, Volume I, Chapter 3, 3.11 

Frequency plan Annex 10, Volume I, Table A 


Annex 10, Volume V, Chapter 4, 4.4 

RTCA MOPS 

Annex 10, Volume I, Attachment G, Section 9 

DO- 177, MOPS for MLS airborne receiving equipment (1986) 


ARINC characteristic 727 

ITU Res./Rec./Reg. Rec. No. 607 (Mob-87): Future requirements of the band 5000- 

5250 MHz for the aeronautical radionavigation service 

ITU-R S.1342 Method for determining coordination distances, in 

the 5 GHz band, between the international standard microwave 

landing system (MLS) in the aeronautical radionavigation service 

(ARNS) and non-geostationary mobile-satellite service stations 

providing feeder uplink services. 

Other material RTCA DO-226 guidance material for evolving airborne precision 

area navigation equipment with emphasis on MLS. 

Band 5350-5470 MHz 


Aviation use Airborne weather radar 

Annex 10 

SARPs Annex 6, Part 1, Chapter 6, 6.11 




RTCA MOPS DO-173 MOPS for airborne weather radar and ground mapping 

pulsed radars (1985) 


ARINC characteristic No. 708 

ITU Res./Rec./Reg. No. 5.448B of the Final Acts of ITU WRC-03 concerning use of 

the Frequency Band 5350-5460 MHz by Spaceborne Active 

Sensors. 

Other material DO-220, MOPS for airborne weather radar with forward-looking 

wind shear detection capability (1993) 

Band 8750-8850 MHz 

Service Aeronautical radionavigation/radiolocation 

Aviation use Airborne Doppler radar 

Annex 10 

SARPs None 




RTCA MOPS DO-220, MOPS for Airborne Weather Radar with forwardlooking 

Windshear detection capability (1993) 





Page 313

Band 9000-9500 MHz 

Service Aeronautical radionavigation/radionavigation 

Aviation use Primary radar 3 cm short-range applications including precision 

approach. Airport surface detection equipment (ASDE) 

Annex 10 

SARPs Annex 10, Volume I, Chapter 3, 3.2 






ARINC characteristic 708 (AWR) 

ITU Res./Rec./Reg. ITU-R M.629: Use for the radionavigation service of the radio 

frequency bands 2900-3100 MHz, 5470-5650 MHz, 9200-9300 

MHz, 9300-9500 MHz and 9500-9800 MHz 


Band 13.25-13.4 GHz 


Aviation use Airborne Doppler radar 

Annex 10 

SARPs None 




RTCA M0PS DO-173, DO-220, DO-158 



ITU Res./Rec./Reg. ITU-R M.496-3: Limits of power flux-density of radionavigation 

transmitters to protect space station receivers in the fixedsatellite 

service in the 14 GHz band 


Page 314

Band 15.4-15.7 GHz 

Service Aeronautical radionavigation/radiolocation 

Aviation use Primary radar particularly airport surface detection equipment 

(ASDE) 

Annex 10 

SARPs None 







ITU Res./Rec./Reg. Res. 719 (WRC-95): Urgent studies required in preparation for 

the 1997 World Radiocommunication Conference; Annex to 

Resolution 719. 

Res. 123 (WRC-97): Feasibility of implementing feeder links of 

non-geostationary satellite networks in the mobile-satellite 

service in the band 15.43-15.63 GHz (space-to-Earth) while 

taking into account the protection of the radio astronomy service, 

the earth exploration-satellite (passive) service and the space 

research (passive) service in the band 15.35- 15.4 GHz. 

Res. 116: Allocation of frequencies to the fixed satellite service 

(space-to-Earth) in the band 15.4-15.7 GHz for feeder links of 

non-geostationary satellite networks in the mobile-satellite 

service 

Res 117: Allocation of frequencies to the fixed satellite service 

(Earth-to-space) in the band 15.45-15.65 GHz for use by feeder 

links of non-geostationary satellite networks operating in the 

mobile satellite service. 

ITU-R S.1340 Sharing between feeder links for the mobilesatellite 

service and the aeronautical radionavigation service in 

the Earth-to-space direction in the band 15.4-15.7 GHz. 

ITU-R S.1341 Sharing between feeder links for the mobilesatellite 

service and the aeronautical radionavigation service in 

the space-to-Earth direction in the band 15.4-15.7 GHz and the 

protection of the radio astronomy service in the band 15.35-15.4 

GHz. 


Page 315

Band 24.25-24.65 GHz 


Aviation use Primary radar: airport surface detection equipment 

Annex 10 

SARPs None 









Band 31.8-33.4 GHz 


Aviation use Airport surface detection equipment 

Annex 10 

SARPs None 







ITU Res./Rec./Reg. Rec. No. 707 (WARC-79): Relating to the use of the frequency 

band 32-33 GHz shared between the inter-satellite service and 

the radionavigation service. 


Page 316

Annex 2-2 Maritime Radiodetermination Standards (SOLAS & Marine 

Equipment Directive) 

Organisation Standard Description 

IEC 62252 Radar for craft not in compliance with IMO SOLAS Chapter V 


systems – Radar plotting aids 


systems – Radar 


systems – General requirements 

IMO IB978E Performance Standards for Shipborne Radiocommunication and 

Navigational Equipment 

IMO IB970E Handbook on the Global Maritime Distress and Safety System 

Page 317

Annex 2-3 Aeronautical Communications Standards 

Band 2850-22000 kHz (selected bands) 

Service AM(R)S 

Aviation use Air-ground communications (HF voice and data) 

Annex 10 

SARPs Annex 10, Volume III, Part II, Chapter 2, 2.4 

Frequency plan Appendix 27 (see ITU below) 

Channelisation 3 kHz spacing SSB 

Planning criteria see ITU below 

RTCA MOPS DO-163, MOPS for airborne HF radio communication 

transmitting/receiving equipment (1976) 


ARINC characteristic 719-5 

ITU Res./Rec./Reg. Appendix 27 to Radio Regulations (Frequency Allotment Plan, 

Planning Criteria). 

Res. No. 207. 

Res. No. 405: Relating to the use of frequencies of the 

aeronautical mobile (R) service. 

Rec. No. 401: Relating to the efficient used of aeronautical 

mobile worldwide frequencies. 

Rec. No. 402: Relating to cooperation in the efficient use of 

worldwide frequencies in the aeronautical mobile (R) service. 

ITU-R M.1458 Use of the frequency bands between 2.8-22 MHz 

by the AM(R)S for data transmission using class of emission 

J2D 

Other material The reports of AMCP/3, AMCP/4, AMCP/5 and ADSP/3 contain 

ICAO material relevant to the development of ASRPs for HF 

data link. 

Bands 3023 kHz and 5680 kHz 


Aviation use Search and rescue (SAR) frequencies in HF 

Annex 10 

SARPs None 

Frequency plan Annex 10, Volume V, Chapter 2, 2.2 



RTCA MOPS DO-163, MOPS for airborne HF radio communications 

transmitting/receiving equipment 



ITU Res./Rec./Reg. Res. No. 403: Relating to the use of frequencies 3023 kHz and 

5680 kHz common to the aeronautical mobile (R) and (OR) 

services 

Other material Radio Regulations, Chapter VII and Appendix 13, Appendix 27 

Band 117.975-137 MHz 


Aviation use Air-ground and air-air communication (VHF voice and data) 

Annex 10 

SARPs Annex 10;Volume III, Part II, Chapter 2, 2.1, 2.2 and 2.3 

Frequency plan Annex 10, Volume V, Chapter 4, 4.1 

Channelisation 25 kHz /8.33 kHz 

Planning criteria Annex 10, Volume V, Attachment A 

Page 318

RTCA MOPS DO 186A - MOPS for airborne radio communications equipment 

operating within the frequency range 117.975-137 MHz (1995). 

EUROCAE MOPS ED-23B 

ARINC characteristic 716-7,750 (Data) 

ITU Res./Rec./Reg. Rec. No. 714 (Mob-87): Compatibility between the aeronautical 

mobile (R) service in the band 117.975-137 MHz and sound 

broadcasting stations in the band 87.5-108 MHz. 

ITU-R IS. 1009: Compatibility between the sound broadcasting 

service in the band 87-108 MHz and the aeronautical services in 

the band 108-137 MHz 


RTCA DO-225: VHF air-ground communication systems 

improvements alternative studies and selection of proposals for 

future action (1994) 

RTCA DO-224: Signal in space MASPS for advanced VHF 

digital data communications, including compatibility with digital 

voice techniques (1994). 

RTCA DO 176 - FM IX: Interference related to airborne ILS, 

VOR and VHF communications (1981). 

Frequency 121.5 MHz, 123.1 MHz, and 243 MHz 

Annex 10 

SARPs Annex 10, Volume III, Part II, Chapter 5 

Frequency plan Annex 10, Volume V, Chapter 4 



RTCA MOPS 

DO 183 MOPS for emergency locator transmitters operating on 

121.5 and 243ÿMHz. 

DO-204, MOPS for 406 MHz emergency locator transmitters 

(ELT) 



ITU Res./Rec./Reg. Resolution 18 (MOB-83) relating to the procedure for identifying 

and announcing the position of ships and aircraft of States not 

parties to an armed conflict. 

Rec. 604 (Rev. Mob-87): Future use and characteristics of 

emergency position-indicating radio beacons (EPIRBs) 

ITU-R M.690: Technical characteristics of emergency position 

indicating radio beacons (EPIRBs) operating on carrier 

frequencies 121.5 MHz and 243 MHz. 


ITU Radio Regulations, Chapter VII and Appendix 13 

DO-182, ELT equipment and installation performance (1982) 

Bands 406-406.1 MHz 

Service Mobile-satellite (Earth-to-space) 

Aviation use 

Annex 10 

Search and rescue 

SARPs Annex 10, Volume III, Part II, Appendix 1 to Chapter 5 

Frequency plan Annex 10, Volume V 



RTCA MOPS 

DO-204, MOPS for 406 MHz emergency locator transmitters 

(ELT)(1994) 

Change 1 to DO-204 (1994) 



ITU Res./Rec./Reg. Res. No. 205 (Rev. Mob-87): Protection of the band 406-406.1 

MHz allocated to the mobile-satellite service 

Page 319

ITU-R M.633 Transmission characteristics of a satellite position 

indicating radio beacon (satellite ERIRB) system operating 

through a low polar orbiting satellite system in the 406 MHz band 


Band 1544-1545 MHz and 1645.5-1646.5 MHz 

Service Mobile satellite 

Aviation use Distress and safety communications (satellite EPIRBs) 

Annex 10 

SARPs None 






ITU Res./Rec./Reg. Radio Regulations: Article 38/Appendix 15 


Band 1545-1555 MHz and 1646.5 MHz 

Service AMS(R)S 

Aviation use Satellite communications 

Annex 10 

SARPs Annex 10, Volume III, Part I, Chapter 4 

Frequency plan Prepared by space segment provider 



RTCA MOPS DO-210D, MOPS for aeronautical mobile-satellite services 

(1996) 


ARINC characteristic 741 P1 (aircraft installation) 741 P2 (satellite design) 741 P4 

(specification and description language. 

ITU Res./Rec./Reg. Res. No. 44 (Mob-87): Compatibility of equipment used in the 

mobile-satellite service 

Res. No. 222 (WRC-2000): Use of the bands 1525-1559 MHz 

and 1626.5-1660.5 MHz by the mobile-satellite service 

ITU-R M.828-1: Definition of availability for communication 

circuits in the mobile-satellite service 

ITU-R M.1037: Bit error performance objectives for the AMS(R)S 

radio links 

ITU-R M.1089: Technical considerations for the coordination of 

mobile-satellite systems supporting the AMS(R)S 

ITU-R M.1233: Technical considerations for sharing satellites 

network resources between the MSS (other than AMS(R)S) and 

AMS(R)S 

ITU-R M.1234: Permissible level of interference in a digital 

channel of a geostationary satellite network in the AMS(R)S in 

the bands 1545-1555 MHz and 1646.5-1656.5 MHz and its 

associated feeder links caused by other networks of this service 

and the FSS. 

Other material AMCP/5 Report 

Page 320

Annex 2-4 Maritime Communications Standards (SOLAS & Marine Equipment 

Directive) 

TITLE IEC STANDARD 

Global maritime distress and safety system (GMDSS) Part 2: IEC 610972 

COSPAS/SARSAT EPIRB Satellite emergency position 

indicating radio beacon operating on 406 MHz Operational and 

performance requirements, methods of testing and required 

test results 

Global maritime distress and safety system (GMDSS) Part 3: 

Digital selective calling (DSC) equipment Operational and 


testing results 


Inmarsat E Emergency position indicating radio beacon 

(EPIRB) operating through the Inmarsat system Operational 

and performance requirements, methods of testing and 

required test results 


Narrowband direct printing telegraph equipment for the 

reception of navigational and meteorological warnings and 

urgent information to ships (NAVTEX) Operational and 


test results 


Shipborne VHF radiotelephone transmitter and receiver - 

Operational and performance requirements, methods of testing 

and required test results 


Shipborne watchkeeping receivers for the reception of digital 

selective calling (DSC) in the maritime MF, MF/HF and VHF 

bands Operational and performance requirements, methods of 

testing and required test results 


Shipborne transmitters and receivers for use in the MF and HF 

bands suitable for telephony, digital selective calling (DSC) and 

narrow band direct printing (NBDP) Operational and 


test results 


Inmarsat B ship earth station equipment Operational and 


test results 


Survival craft portable two-way VHF radiotelephone apparatus 



IEC 610973 

IEC 610975 

IEC 610976 

IEC 610977 

IEC 610978 

IEC 610979 

IEC 6109710 

IEC 6109712 

Page 321

Global navigation satellite systems (GNSS) Part 1: Global 

positioning system (GPS) Receiver equipment Performance 

standards, methods of testing and required test results 

Maritime navigation and radiocommunication equipment and 

systems Global navigation satellite systems (GNSS) Part 2: 

Global navigation satellite system (GLONASS) Receiver 

equipment Performance standards, methods of testing and 

required test results 


systems Part 1: Shipborne automatic transponder system 

installation using VHF digital selective calling (DSC) 

techniques Operational and performance requirements, 

methods of testing and required test results 


Narrow band direct printing (NBDP) equipment (radiotelex) - 




Reserve sources of energy Operational and performance 

requirements, methods of testing and required test results 



Combined GPS and GLONASS systems Receiver equipment - 

Performance standards, methods of testing and required test 

results 



Differential GPS/GLONASS systems Receiver equipment - 

Performance standards, methods of testing and required test 

results 


systems Integrated Navigation Systems Operational and 


test results 


systems Part 2: Shipborne Universal Automatic Identity 

transponder System (UAIS) Operational and performance 

requirements, methods of testing and required test results 

IEC 611081 

IEC 611082 

IEC 619931 

IEC 6109711 

IEC 6109714 

IEC 611083 

IEC 611084 

IEC 61924 

IEC 619932 

Page 322

ETSI STANDARDS 

DESIGNATION ETSI STANDARDS 

VHF radio installation capable of transmitting and receiving EN 300 162, EN 300 

DCS and radio telephony 

338, EN 300 828 

VHF DSC Watchkeeping receiver EN 300 338, EN 300 

828, EN 301 033 

NAVTEX receiver EN 300 065, EN 301 

011 

EGC Receiver ETS 300 460, EN 300 

829 

HF Maritime Safety Information (MSI) equipment (HF NBDP 

receiver) 

EN 300 067 

406 MHz EPIRB (COSPAS-SARSAT) EN 300 066 

L-band EPIRB (INMARSAT) ETS 300 372 

2182 kHz watch receiver ETS 300 441, EN 301 

090 

Two-tone alarm signal generator EN 300 373 

MF radio installation capable of transmitting and receiving 

DSC and radio telephony 

EN 300 338, EN 300 

373 

MF radiotelephone DSC watchkeeping receiver EN 300 338, EN 301 

033 

Inmarsat C SES ETS 300 460, EN 300 

829 

MF/HF radio installation capable of transmitting and 

receiving DSC, NBDP and radiotelephone 

EN 300 338, EN 300 

373, ETS 300 067 

Radiotelephone MF/HF DSC watchkeeping receiver EN 300 338, EN 301 

033 

Aeronautical two-way VHF radio telephone apparatus EN 301 688 

Portable survival craft two-way VHF radiotelephone 

apparatus 

Final survival craft two-way VHF radiotelephone apparatus EN 301 466 

Electro Magnetic Compatibility (EMC) for Maritime Mobile 

Earth Stations (MMES) operating in the 1,5/1,6 GHz bands 

providing Low Bit Rate Data Communications (LBRDC) for 

the Global Maritime Distress and Safety System (GMDSS) 

EN 300 225, EN 300 

828 

EN 300 829 

Page 323

ANNEX 3 Harmonised Standards (R&TTE Directive) and 

Interface Requirements 

Radio equipment which is not covered by IMO carriage requirements is covered by the 

Radio and Telecommunications Terminal Equipment Directive. 

Annex 3-1 Maritime Radiodetermination Standards 

DESIGNATION STANDARD 

IEC Standard - Maritime navigation and radiocommunication 

equipment and systems – Radar 

IEC 60936 

UK MARITIME RADIODETERMINATION INTERFACE REQUIREMENTS 

TITLE REFERENCE 

UK Radio Interface Requirement 2020 for Radar 9 GHz 

2020 

(non-SOLAS) in the maritime radionavigation service – IEC 

60936 

UK Radio Interface Requirement 2031 for Racons (3GHz 

and 9GHz) in the maritime radionavigation service (ITU-R 

M.824) 

UK Radio Interface requirement 2032 for transmission of 

differential correction signals of Global Navigation Satellite 

Systems (DGNSS) from Maritime Radio stations in the 

Frequency Bands 162.4375-162.4625 and 163.0125- 

163.03125 MHz 

UK Radio Interface Requirement 2033 for a universal 

shipborne automatic identification system using time 

division multiple access in the VHF band of the maritime 

mobile service for use coast stations 

UK Radio Interface Requirement 2034 for Radio Beacons of 

the Maritime Radiodetermination Service in the Frequency 

Band 283.5-315 kHz 

2031 

2032 

2033 

2034 

Page 324

Annex 3-2 Maritime Communications Equipment Standards outside the 

SOLAS Convention and the Marine Equipment Directive 

ETSI STANDARDS 

DESIGNATION ETSI 

STANDARD 

UHF EQUIPMENT 

Ultra-High Frequency (UHF) on-board communications 

systems and equipment 

VHF EQUIPMENT 

Radiotelephone transmitters and receivers for the maritime 

mobile service operating in VHF bands 

Radiotelephone transmitters and receivers for the maritime 

mobile service operating in VHF bands 

EN 300 720 

EN 300 162 

EN 301 925 

Survival craft portable VHF radiotelephone apparatus ETS 300 225 

Electro Magnetic Compatibility (EMC) for radiotelephone 

transmitters and receivers for the maritime mobile service 

operating in the VHF bands 

Two-way VHF radiotelephone apparatus for fixed installation 

in survival craft 

Radio telephone transmitters and receivers for the maritime 

mobile service operating in the VHF bands used on inland 

waterways 

Portable Very High Frequency (VHF) radiotelephone 

equipment for the maritime mobile service (for non-GMDSS 

applications only) 

VHF transmitters and receivers for Coastal Stations for 

GMDSS and other applications in the maritime mobile service 

MF/HF EQUIPMENT 

Maritime mobile transmitters and receivers for use in the MF 

and HF bands 

Radiotelex equipment operating in the Maritime MF/HF 

service 

EN 300 828 

EN 301 466 

EN 300 698 

EN 301 178 

EN 301 929 

EN 300 373 

EN 300 067 

Maritime MF/HF radio equipment Class E DEN/ERM-RP01-054 

Page 325

DIGITAL SELECTIVE CALLING (DSC) EQUIPMENT 

Equipment for generation, transmission and reception of 

Digital Selective Calling (DSC) in the maritime MF, MF/HF 

and/or VHF mobile service 

Shipborne watchkeeping receivers for reception of Digital 

Selective Calling (DSC) in the maritime MF, MF/HF and VHF 

bands 

VHF radiotelephone equipment for general communications 

and associated equipment for Class "D" Digital Selective 

Calling (DSC) 

EMERGENCY POSITION INDICATING RADIO BEACONS (EPIRB) 

Float-free maritime satellite Emergency Position Indicating 

Radio Beacons (EPIRBs) operating on 406.025 MHz 

Maritime Emergency Position Indicating Radio Beacons 

(EPIRBs) intended for use on the frequency 121,5 MHz or 

the frequencies 121,5 MHz and 243 MHz for homing 

purposes only 

Maritime float-free satellite Emergency Position Indicating 

Radio Beacon (EPIRB) operating in the 1,6 GHz band 

through geostationary satellites 

PERSONAL LOCATOR BEACONS (PLB) 

Satellite Personal Locators Beacons (PLBs) operating in the 

406,0 MHz to 406,1 MHz frequency band 

NAVTEX EQUIPMENT 

Narrow band direct printing telegraph equipment for 

receiving meteorological or navigational information 

(NAVTEX) 

Electro Magnetic Compatibility (EMC) standard for Narrow 

Band Direct Printing (NBDP) NAVTEX receivers operating in 

the maritime mobile service 

Non printing narrow band telegraph equipment for receiving 

meteorological or navigational information (NAVTEX) 

EN 300 338 

EN 301 033 

EN 301 025 

EN 300 066 

EN 300 152 

EN 300 372 

DEN/ERM-TG26-056 

EN 300 065 

EN 301 011 

MARITIME EQUIPMENT FOR COMMUNICATING WITH AIRCRAFT 

Fixed and portable VHF equipment operating on 121,5 MHz 

and 123,1 MHz 

DEN/ERM-RP01-053 

EN 301 688 

Page 326

MARITIME SATELLITE EQUIPMENT 

Network Control Facilities (NCF) for Maritime Mobile Earth 

Stations (MMES) operating in the 1,5/1,6 GHz and 11/12/14 

GHz bands providing Low Bit Rate Data Communications 

(LBRDC) 

Maritime Mobile Earth Stations (MMES) operating in the 

1,5/1,6 GHz bands providing Low Bit Rate Data 

Communications (LBRDC) for the Global Maritime Distress 

and Safety System (GMDSS) 

Maritime Mobile Earth Stations (MMES) operating in the 

1,5/1,6 GHz bands providing Low Bit Rate Data 

Communications (LBRDC) in the Maritime Mobile Satellite 

Service (MMSS), not intended for distress and safety 


Maritime Mobile Earth Stations (MMESs) operating in the 1,5 

GHz and 1,6 GHz providing voice and/or data for the Global 

Maritime Distress and Safety System (GMDSS) 

MARITIME EMC 

Electro Magnetic Compatibility (EMC) for radiotelephone 

transmitters and receivers for the maritime mobile service 

operating in the VHF bands 

Electro Magnetic Compatibility (EMC) standard for Narrow- 

Band Direct-Printing (NBDP) NAVTEX receivers operating in 

the maritime mobile service 

Electro Magnetic Compatibility (EMC) standard for Maritime 

radio equipment and services covered by the R&TTE 

Directive 

ETS 300 459 

ETS 300 460 

ETS 300 740 

DEN/ERM-RP01-034 

EN 300 828 

EN 301 011 

EN 301 843 

UK MARITIME INTERFACE REQUIREMENTS FOR R&TTE DIRECTIVE 

TITLE REFERENCE 

UK Radio Interface Requirement 2021 for VHF transmitters 2021 

and receivers for use at coast stations in the maritime 

mobile service 

UK Radio Interface Requirement 2023 for transmitters and 

receivers in the MF/HF bands for use at coast stations in the 

maritime mobile service 

UK Radio Interface Requirement 2024 for portable 

radiotelephone equipment in the maritime mobile service 

operating in the VHF bands (for non-GMDSS applications 

only) 

UK Radio Licence Interface Requirement 2025 for a 

universal shipborne automatic identification system using 

time division multiple access in the VHF band of the 

maritime mobile service 

2023 

2024 

2025 

Page 327

UK Radio Licence Interface Requirement 2026 for VHF 

radiotelephone equipment for general communications and 

associated equipment for Class "D" Digital Selective Calling 

(DSC) 

UK Radio Interface Requirement 2029 for Maritime 

Emergency Position indicating Radio Beacons (EPIRBs) 

intended for use on the frequency 121,5MHz or the 

frequencies 121,5 MHz and 243 MHz for homing purposes 

only 

UK Radio Interface requirement 2032 for transmission of 

differential correction signals of Global Navigation Satellite 

Systems (DGNSS) from Maritime Radio stations in the 

Frequency Bands 162.4375-162.4625 and 163.0125- 

163.03125 MHz 

UK Radio Interface Requirement 2033 for a universal 

shipborne automatic identification system using time 

division multiple access in the VHF band of the maritime 

mobile service for use coast stations 

UK Radio Interface Requirement 2034 for Radio Beacons of 

the Maritime Radiodetermination Service in the Frequency 

Band 283.5-315 kHz 

UK Radio Interface Requirement 2035 for maritime UHF onboard 

communications systems and equipment. 

UK Radio Interface Requirement 2039 for hand-held / 

transportable radiotelephone equipment with DSC Distress 

Alerting Capability in the maritime mobile service operating 

in the VHF bands (for non-SOLAS applications only) 

UK Radio Interface Requirement 2042 for Maritime 

Personal Locator Beacons (PLBs) intended for use with the 

COSPAS-SARSAT Distress Alert System on the 

frequencies 406.025MHz or 406.028MHz, with an auxiliary 

121.5MHz transmitter for homing purposes only, and 

optional Navigational Interface (either Internal or External) 

2026 

2029 

2032 

2033 

2034 

2035 

2039 

2042 

Page 328

ANNEX 4 List of pertinent ITU Recommendations for 

Maritime Services 

Direct-printing telegraph equipment in the maritime mobile 

service 

Technical characteristics of VHF radiotelephone equipment 

operating in the maritime mobile service in channels spaced 

by 25 kHz 

Operational procedures for the use of direct-printing 

telegraph equipment in the maritime mobile service 

Digital selective-calling system for use in the maritime 

mobile service 

Operational and technical characteristics for an automated 

direct-printing telegraph system for promulgation of 

navigational and meteorological warnings and urgent 

information to ships 

Operational procedures for the use of digital selectivecalling 

equipment in the maritime mobile service 

ITU-R M 476 

ITU-R M 489 

ITU-R M 492 

ITU-R M 493 

ITU-R M 540 

ITU-R M 541 

Characteristics of maritime radio beacons (Region 1). ITU-R M 588 

Direct-printing telegraph equipment in the maritime mobile 

service 

Technical characteristics of VHF radiotelephone equipment 

operating in the maritime mobile service in channels spaced 

by 25 kHz 

Use of hyperbolic maritime radionavigation systems in the 

band 283.5-315 kHz 

Transmission characteristics of a satellite emergency 

position-indicating radio beacon (satellite EPIRB) system 

operating through geostationary satellites in the 1.6 GHz 

band 

Technical characteristics for a high frequency direct-printing 

telegraph system for promulgation of high seas and 

NAVTEX-type maritime safety information 

Technical characteristics of emergency position-indicating 

radio beacons (EPIRBs) operating on the carrier 

frequencies of 121.5 MHz and 243 MHz 

Technical characteristics of VHF emergency positionindicating 

radio beacons using digital selective calling (DSC 

VHF EPIRB) 

Technical characteristics of differential transmissions for 

Global Navigation Satellite Systems from maritime radio 

beacons in the frequency band 283.5-315 kHz in Region 1 

and 285-325 kHz in Regions 2 and 3 

ITU-R M 625 

ITU-R M 627 

ITU-R M 631 

ITU-R M 632 

ITU-R M 688 

ITU-R M 690 

ITU-R M 693 

ITU-R M 823 

Technical Parameters for Radar Beacons (RACONs) ITU-R M 824 

Operational procedures for mobile-satellite networks or 

systems in the bands 1 530-1 544 MHz and 1 626.5- 

ITU-R M 830 

Page 329

1 645.5 MHz which are used for distress and safety 

purposes as specified for GMDSS 

Interim solutions for improved efficiency in the use of the 

band 156-174 MHz by stations in the maritime mobile 

service 

ITU-R M 1084 

Morse telegraphy procedures in the maritime mobile service ITU-R M 1170 

Radiotelephony procedures in the maritime mobile service ITU-R M 1171 

Technical characteristics of single-sideband transmitters 

used in the maritime mobile service for radiotelephony in the 

bands between 1 606.5 kHz (1 605 kHz Region 2) and 

4 000 kHz and between 4 000 kHz and 27 500 kHz 

Technical characteristics of equipment used for on-board 

vessel communications in the bands between 450 and 470 

MHz 

Use of the maritime radionavigation band 283.5-315 kHz 

(Region 1) and 285-325 kHz (Regions 2 and 3) 

A long-term solution for improved efficiency in the use of the 

band 156-174 MHz by stations in the maritime mobile 

service 

ITU-R M 1173 

ITU-R M 1174 

ITU-R M 1178 

ITU-R M 1312 

Technical characteristics of maritime radionavigation radars ITU-R M.1313 

Methods to reduce radar unwanted emissions ITU-R M.1314 

Technical characteristics for a universal shipborne 

automatic identification system using time division multiple 

access in the VHF maritime mobile band 

Technical and operational characteristics and protection 

criteria of radiodetermination and meteorological radars in 

the 2 900-3 100 MHz band 

Procedures for determining the potential for interference 

between radars operating in the radiodetermination service 

and systems in other services 

Characteristics of and protection criteria for radars operating 

in the radiodetermination service in the frequency band 1 

215-1 400 MHz 

Characteristics of and protection criteria for radionavigation 

and meteorological radars operating in the frequency band 

2 700-2 900 MHz 

Characteristics of and protection criteria for radars operating 

in the radiodetermination service in the frequency band 3 

100-3 700 MHz 

ITU-R M 1371 

ITU-R M 1460 

ITU-R M 1461 

ITU-R M 1463 

ITU-R M 1464 

ITU-R M 1465 

Page 330

ANNEX 5 Structure of the 4, 6 and 8 MHz HF Maritime Bands 

Sub-band structure of the 4 MHz maritime band 

4.05 4.1 4.2 4.3 4.4 4.45 

4 063.3 063.3 – – 4 064.8 4 064.8 oceanographic oceanographic research research communications communications - 6 × 0.3kHz chs - 6 × 0.3kHz chs 

4 066.4 – 4 114.4 ship-to-shore radiotelephony - 27 × 3kHz chs 


4 147.4 – 4 150.4 simplex radiotelephony - 2 × 3kHz chs 

4 147.4 – 4 150.4 simplex radiotelephony - 2 × 3kHz chs 

4 154.0 – 4 170.0 ship-to-shore wideband telegraphy, facsimile - 5 × 4kHz chs 

4 154.0 – 4 170.0 ship-to-shore wideband telegraphy, facsimile - 5 × 4kHz 

chs 4 172.5 – 4 181.5 ship-to-shore NBDP (Telex) - 18 × 0.5kHz chs 

4 181.75 – 4 186.75 ship-to-shore Morse telegraphy calling chs 

4 172.5 – 4 181.5 ship-to-shore NBDP (Telex) - 18 × 0.5kHz chs 

4 187.0 – 4 202.0 ship-to-shore Morse telegraphy working channels - 31 × 0.5kHz chs 

4 181.75 – 4 186.75 ship-to-shore Morse telegraphy calling chs 

4 202.5 – 4 207.5 simplex NBDP (Telex) - 10 × 0.5kHz chs 

4 187.0 – 4 202.0 ship-to-shore Morse telegraphy working channels - 31 × 

0.5kHz 4 207.5 – chs 4 209.0 ship-to-shore DSC - 4 × 0.5kHz chs 

4 209.5 – 4 219.0 shore-to-ship NBDP (Telex) - 20 × 0.5kHz chs 


4 219.5 – 4 220.5 shore-to-ship DSC – 3 × 0.5kHz chs 

4 207.5 – 4 209.0 ship-to-shore DSC - 4 × 0.5kHz chs 

4 221.0 – 4 351.0 shore-to-ship wideband telegraphy, facsimile, NBDP, special etc 


4 352.4 – 4 436.4 shore-to-ship radiotelephony - 29 × 3kHz chs 

Page 331 

Colour key 

Radiotelephony 

Wideband and Morse telegraphy, fax, 

etc 

Oceanographic research 

Morse telegraphy 

NBDP – narrow-band direct-printing (tlx) 

DSC - digital selective calling 

Ship station channels 

Coast station channels 

Simplex channels


6.2 6.3 6.4 6.5 


6 225.4 201.4 – – 6 6 231.4 224.4 simplex ship-to-shore radiotelephony radiotelephony - 3 × 3kHz chs - 8 × 3kHz chs 

6 235.0 225.4 – – 6 6 259.0 231.4 ship-to-shore simplex radiotelephony wideband telegraphy, - 3 × 3kHz facsimile chs - 7 × 4kHz chs 

6 261.3 235.0 – 6 6 262.5 259.0 oceanographic ship-to-shore research wideband communications telegraphy, - facsimile 5 × 0.3kHz - 7 chs × 4kHz chs 

6 263.0 261.3 – 6 6 275.5 262.5 ship-to-shore oceanographic NBDP research (Telex) - 25 communications × 0.5kHz chs - 5 × 0.3kHz chs 

6 275.75 263.0 – 6 6 280.75 275.5 ship-to-shore Morse NBDP telegraphy (Telex) - calling 25 × 0.5kHz chs chs 

6 281.0 275.75 – 6 – 284.5 6 280.75 ship-to-shore ship-to-shore NBDP Morse (Telex) telegraphy - 8 × 0.5kHz calling chs chs 

6 285.0 281.0 – – 6 6 300.0 284.5 ship-to-shore Morse NBDP telegraphy (Telex) working - 8 × 0.5kHz channels chs - 31 × 0.5kHz chs 


6 285.0 – 6 300.0 ship-to-shore Morse telegraphy working channels - 31 × 0.5kHz 

chs 6 312.0 – 6 313.5 ship-to-shore DSC - 4 × 0.5kHz chs 

6 314.0 300.5 – 6 6 330.5 311.5 shore-to-ship simplex NBDP NBDP (Telex) - - 23 34 × 0.5kHz chs 

6 331.0 312.0 – 6 6 332.0 313.5 shore-to-ship ship-to-shore DSC DSC – 3 × - 0.5kHz 4 × 0.5kHz chs chs 



Page 332 

Colour key 



etc 







Simplex channels


8.1 8.2 8.3 8.4 8.5 8.6 8.7 8.8 

8 100.0 – 8 8 195.0 simplex radiotelephony 

8 196.4 – 8 8 292.4 ship-to-shore radiotelephony - 33 × - 3kHz 33 × chs 3kHz chs 

8 295.4 – – 8 8 298.4 298.4 simplex simplex radiotelephony - 2 × - 3kHz 2 × 3kHz chs chs 

8 302.0 – 

– 

8 

8 

338.0 

338.0 

ship-to-shore 

ship-to-shore 

wideband 

wideband 

telegraphy, 

telegraphy, 

facsimile 

facsimile 

- 7 × 4kHz 

- 7 

chs 

× 4kHz chs 

8 340.3 – 8 341.5 oceanographic research communications - 5 × 0.3kHz chs 

8 340.3 – 8 341.5 oceanographic research communications - 5 × 0.3kHz chs 

8 342.0 – 8 365.5 ship-to-shore Morse telegraphy working channels - 48 × 0.5kHz chs 

8 342.0 – 8 365.5 ship-to-shore Morse telegraphy working channels - 48 × 0.5kHz 

chs 8 365.75 – 8 370.75 ship-to-shore Morse telegraphy calling chs 

8 371.0 365.75 – 8 – 376.0 8 370.75 ship-to-shore Morse Morse telegraphy telegraphy working channels calling chs - 11 × 0.5kHz chs 

8 376.5 371.0 – – 8 8 396.0 376.0 ship-to-shore NBDP Morse (Telex) telegraphy - 40 × 0.5kHz working chs channels - 11 × 0.5kHz 

chs 


8 376.5 – 8 396.0 ship-to-shore NBDP (Telex) - 40 × 0.5kHz chs 

8 414.5 – 8 416.0 ship-to-shore DSC - 4 × 0.5kHz chs 



8 436.5 414.5 – – 8 8 437.5 416.0 shore-to-ship ship-to-shore DSC DSC – 3 × - 0.5kHz 4 × 0.5kHz chs chs 



Page 333 

Colour key 



etc 







Simplex channels

ANNEX 6 Concerning AIS Carriage Requirements 

MSC 73/21/Add.2 ANNEX 7 Page 137 

2.4 All ships of 300 gross tonnage and upwards engaged on international voyages and 

cargo ships of 500 gross tonnage and upwards not engaged on international voyages and 

passenger ships irrespective of size shall be fitted with an automatic identification system 

(AIS), as follows: 

1. ships constructed on or after 1 July 2002; 

2. ships engaged on international voyages constructed before 1 July 2002: 

2.1. in the case of passenger ships, not later than 1 July 2003; 

2.2. in the case of tankers, not later than the first survey for safety equipment* 

on or after 1 July 2003; 

2.3. in the case of ships, other than passenger ships and tankers, of 50,000 gross 

tonnage and upwards, not later than 1 July 2004; 


tonnage and upwards but less than 50,000 gross tonnage, not later than 1 

July 2005; 



July 2006. 

2.6. in the case of ships, other than passenger ships and tankers, of 300 gross 


July 2007; and 

3. ships not engaged on international voyages constructed before 1 July 2002, not later 

than 1 July 2008; 

4. the Administration may exempt ships from the application of the requirements of 

this paragraph when such ships will be taken permanently out of service within two 

years after the implementation date specified in subparagraphs .2 and .3; 

5. AIS shall: 

5.1. provide automatically to appropriately equipped shore stations, other ships 

and aircraft information, including the ship's identity, type, position, 

course, speed, navigational status and other safety-related information; 

Refer to regulation I/8. 

I:\MSC\73\21a2.DOC 

MSC 73/21/Add.2 ANNEX 7 Page 138 

Page 334

5.2. receive automatically such information from similarly fitted ships; 

5.3. monitor and track ships; and 

5.4. exchange data with shore-based facilities; 

6. the requirements of paragraph 2.4.5 shall not be applied to cases where 

international agreements, rules or standards provide for the protection of 

navigational information; and 

7. AIS shall be operated taking into account the guidelines adopted by the 

Organization.* 

SOLAS/CONF.5/DC/1 ANNEX Page 4 

ANNEX 

[DRAFT] AMENDMENTS TO THE INTERNATIONAL CONVENTION FOR THE SAFETY OF 

LIFE AT SEA, 1974 AS AMENDED 

CHAPTER V SAFETY OF NAVIGATION 

Regulation 19 - Carriage requirements for shipborne navigational systems and equipment 

1 The existing subparagraphs .4, .5 and .6 of paragraph 2.4.2 are replaced by the following: 

“.4 in the case of ships, other than passenger ships and tankers, of 300 gross tonnage 

and upwards but less than 50,000 gross tonnage, not later than the first safety 

equipment survey 1 

after 1 July 2004 or by 31 December 2004, whichever occurs 

earlier; and” 

2 The following new sentence is added at the end of the existing subparagraph .7 of paragraph 2.4: 

“Ships fitted with AIS shall maintain AIS in operation at all times except where international 

agreements, rules or standards provide for the protection of navigational information.” 

CHAPTER XI SPECIAL MEASURES TO ENHANCE MARITIME SAFETY 

3 The existing chapter XI is renumbered as chapter XI-1. 

Regulation 3 - Ship identification number 

4 The following text is inserted after the title of the regulation: 

“(Paragraphs 4 and 5 apply to all ships to which this regulation applies. For ships 

constructed before [1 July 2004], the requirements of paragraphs 4 and 5 shall be complied 

with not later than the first scheduled dry-docking of the ship after [1 July 2004])” 

5 The existing paragraph 4 is deleted and the following new text is inserted: 

“4 The ship’s identification number shall be permanently marked: 

Page 335

ANNEX 7 References 

Annex 7-1 Aeronautical Radiodetermination References – Chapter 3 

The Report of an Investigation into the Characteristics, Operation and Protection 

Requirements of Civil Aeronautical and Civil Maritime System Radar” Alenia Marconi 

Systems 

ITU Radiocommunication Study Group document 8B/28-E - “Use of Statistical and 

Operational Aspects in the Radar’s Protection Criteria” 

Efficient use of the radio spectrum by radar stations –Rec. ITU-R M.1372-1 

Unwanted Emissions in the Out of band Domain ITU-R SM1541 

Considering the Concept of Spectrum Efficiency as applied to Radar SE34(01) 35 

Introduction to Radar Systems Third Edition Merril L. Skolnik 

ICAO Annex 10 Volume IV – “Aeronautical Communications – Surveillance Radar and 

Collision Avoidance Systems” – July 2002. 

EUROCONTROL Mode S Programme – http://www.eurocontrol.int/mode_s/ 

European Commission Roadmap for the Implementation of Datalink Services in European 

ATM – Technology Assessment – version 5.0 – February 2003. 

EUROCONTROL STATFOR Medium Term Forecast of Annual Number of IFR Flights – 

http://www.eurocontrol.int/statfor/forecasts/index.html 

ICAO Document 9718 – AN/957 – Handbook on Radio Frequency Spectrum Requirements 

for Civil Aviation – Third Edition 2003. 

EUROCONTROL ADS Programme – 

http://www.eurocontrol.int/ads/ADS_Programme_content.htm 

ICAO Doc 9688 – Manual of Mode S Specific Services – First Edition, 1997 

ED-73A: Minimum Operational Performance Specification for Secondary Surveillance 

Radar Mode S Transponders, May 1995 

DO-260a, Minimum Operational Performance Standards for 1090 MHz Automatic 

Dependent Surveillance – Broadcast (ADS-B), RTCA SC-186, April 2003 (Also published 

as an earlier draft by EUROCAE as ED-102) 

Technical Link Assessment Report, EUROCONTROL, March 2001 

RTCA Minimum Aviation System Performance Standards for Automatic Dependent 

Surveillance Broadcast, DO-242A, June 2002 

RTCA Minimum Operational Performance Standards for Universal Access Transceiver, 

DO-282, August 2002. 

United Kingdom Table of Radio Frequency Allocations, RA365 

http://www.ofcom.org.uk/static/archive/ra/publication/ra_info/ra365.htm 

Northwest European LORAN-C System – http://www.nels.org/index.html 

EUROCONTROL Navigation Strategy for ECAC – edition 2.1, March 1999. 

Federal Radionavigation Plan 2001 (DoD, Department of Transport, USA). 

EUROCONTROL Transition Plan for the Implementation of the Navigation Strategy in ECAC 

2000-2015+, edition 3, May 2000. 

CAA SRG Cap 670 – ATS Safety Requirements – June 2003. 

Page 336

UK Communications Act 2003 (and EC Communications Directives) 

ICAO APANPIRG – Ultra-Wide Band Technology paper – 20 th July 2001. 

Ofcom 1215-1300MHz report (ARNS/RNSS) 

Page 337

Annex 7-2 Maritime Radiodetermination References – Chapter 4 

IMO resolution A.578 (14) Guidelines for Vessel Traffic Services. 

Radar, Sonar & Navigation Industry News 2003-08-07. 

Norwegian Frequency Allocation table – 

http://www.npt.no/pt_internet/ressursforvaltning/frekvenser/frekvensplan/shf_table.html 

Recommendation ITU-R M.824-2, Technical Parameters for Radar Beacons (RACONs) 

Recommendation ITU-R SM. 1372-1 Efficient use of the radio spectrum by radar stations in 

the radiodetermination service 

Transport Trends, UK Government Department for Transport 

Page 338

Annex 7-3 Aeronautical Communications References – Chapter 5 

HFDL 

HFDL SARPS, ICAO Annex 10, Volume III, Chapter 11, Amendment 74, 1999 . 

DO265, MOPS for Aeronautical Mobile High Frequency Data Link (HFDL). 

DO 277, Minimum Aviation System Performance Standards (MASPS) for the High 

Frequency Data Link Operating in the Aeronautical Mobile (Route) Service (AM(R)S), 

March 2002 . 

SC-188, Minimum Aviation System Performance Standards (MASPS) for High Frequency 

Data Link (HFDL). 

ARINC Characteristics 753 for HF Data Radio (HFDR) and HF Data Unit (HFDU). 

AMSS 

’System Definition Manual’, Inmarsat Maritime Safety Services, Version 2c July 1997. 

Draft 8 of Supplement 10 to ARINC Characteristic 741, “Aviation Satellite Communication 

System, Part 1, Aircraft Installation Provisions”. 

Draft 3 of Supplement 7 to ARINC Characteristic 741, “Aviation Satellite Communications 

System, Part 2, System Design and Equipment Functional Description”. 

D-215A, Guidance on Aeronautical Mobile Satellite Service (AMSS) End-to End System 

Performance. 

D0-270, MASPS for the Aeronautical Mobile-Satellite (R) Service (AMS(R)S) as used in 

Aeronautical Data Links. 

DO-231 Design Guidelines and Recommended Standards for the Implementation and Use 

of AMS(R)S Voice Services in a Data Link Environment. 

DO-222, Guidelines on AMS(R)S Near-Term Voice Implementation and Utilization. 

Satellite Earth Stations and Systems (SES); Aircraft Earth Stations (AES) operating under 

the Aeronautical Mobile Satellite Service (AMSS)/Mobile Satellite Service (MSS) and/or the 

Aeronautical Mobile Satellite in Route Service (AMSIS/ Mobile Satellite Service (MSS), 

ETSI EN 301 473 v 1.2.2 February 2001. 

Satellite Earth Stations and Systems (SES); Survey on the need for an ETS for Aircraft 

Earth Stations (AES) in the Aeronautical Mobile Satellite Service (AMSS), May 1996. 

Honeywell and Thales receive Inmarsat Swift 64 High Speed Data Approval, Airfax2000, 

April 16th 2002. 

VDL Mode 2 

Standards and Recommended Practices (SARPs) for VHF Digital Link, Annex 10, Volume 

III, Part I, ICAO. 

Draft Manual on Detailed Technical Specifications for the VDL Mode 2 Digital Link. 

ED-92: Minimum Operational Performance Specification for an Airborne VDL Mode-2 

Transceiver Operating in the frequency range 118-136.975 MHz. 

Page 339

VHF air-ground Digital Link (VDL) Mode 2; Technical characteristics and methods of 

measurement for ground-based equipment; Part 1: Physical layer, EN 301 841-1 

(published), Part 2: Data link layer, EN 301 841-2 (draft), ETSI, 2002. 

LINK 2000+ Programme Master Plan, Version 0.94. 

Euro VDL Mode 2 – Project Overview, Version 2.0. 

631-3 VHF Digital Link Implementation Provisions Functional Description, October 2000, 

ARINC. 

EUROCONTROL VDL-2 day presentations, 18th April 2001. 

VDL-2 Physical layer validation report, EUROCONTROL COM -5-11-0501. 

PETAL-II Transition and Final Report, Volume 1, EUROCONTROL, May 2002. 

PETAL-II Transition and Final Report, Volume 2, EUROCONTROL, May 2002. 

VDL Mode 3 



Technical Manual – AMCP/7-WP81 Appendix B to the report on Agenda Item 1. 

Implementation Manual – AMCP/7-WP81 Appendix C to the report on Agenda Item 1. 

DO-271, Minimum Operational Performance Standards (MOPS) for Aircraft VDL Mode 3 

Transceiver Operating in the Frequency range 117.975-137.000 MHz, RTCA. 

DO-224A, Signal-in-Space Minimum Aviation System Performance Standards (MASPS) for 

Advanced VHF Digital Data Communications Including Compatibility with Digital Voice 

Techniques, RTCA. 

GAO-02-710 National Airspace System, FAA’s approach to its New Communication 

system appears prudent, but challenges remain, FAA, July 2002. 

NEXCOM System Requirements Document, FAA-E-2958, FAA, January 2002. 

NEXCOM Multimode Digital Radio, FAA-E-2938, FAA, July 2001 

NEXCOM Next Generation Air/Ground Communications, Jim Eck, FAA, October 2001. 

NEXCOM Avionics Approach, Sandra Anderson, FAA, October 2001. 

Why VDL-3? The rationale behind the FAA’s technology choice for NEXCOM, FAA, 

September 2001. 

DO-279, Next Generation Air/Ground Communications (NEXCOM) Principles of operation 

for VDL Mode 3, RTCA 

VDL Mode 4 

Draft Manual on Detailed Specifications for the VDL Mode 4 Digital Link (EUROCONTROL 

working draft post AMCP WG-M/2), EUROCONTROL (ICAO), 21 January 2002. 



ED-108: Interim MOPS for VDL Mode 4 Aircraft Transceiver for ADS-B EUROCAE, July 

2001. 

Technical Link Assessment Report, EUROCONTROL, March 2001. 

Page 340

Summary of the Functional and Technical Assessment of the ADS-B Link Architecture 

Alternatives, Interim Report, FAA, November 7 2001. 

Simulation of ADS-B using VDL Mode 4 in the LA Basin and Core European Airspace, 

Swedish CAA, Version 3.0, June 1999 . 

VDL Mode 4 in A-SMGCS – Performance Simulations, LFV, January 2002. 

ATC Simulation Report: Delegated Airborne Separation during Approach and Climb Out. 

May 2000, NUP, SATSA. 

NGSS 

Report on agenda item 3 of the 7th meeting of the aeronautical mobile communication 

council, Montreal, ICAO, 22-30, March 2000. 

DO-262, MOPS for Avionics Supporting Next Generation Satellite Systems (NGSS). 

Inventory of Potential ATS and AOC Applications to be served by emerging NGSS, 

EMERTA/WP2.1.1/AATM/04, European Commission, September 1999. 

Long Term Benefits of NGSS, EMERTA/WP2/DERA/002/0.4 European Commission Oct 

2000. 

NGSS Capabilities, EMERTA/WP2.1.2/SOF/0.4, European Commission October 2000. 

NGSS Study Synthesis Report, EMERTA/WP201/SOF/2.0, March 2001. 

Iridium Aviation Datalinks for ADS”, Final Report, Version 0.9, 5 th July 1999. 

SDLS 

Satellite Data Link System (SDLS), Claude Loisy ESA, 30 January 2002. 

Satellite Data Link System (SDLS) Satellite Data Link System (SDLS), Present Status and 

Projected Future Activities, Claude Loisy, ESA, October 2001. 

Preliminary Study of Satellite Spectrum Requirements - Review and Update of ESA SDLS 

and IATA studies, EUROCONTROL COM-SAT-REQ-D1, Edition 1.1, April 2002. 

Satellite Data Link System (SDLS) - A Dedicated Mobile Satellite Communication System 

Responding to the Highly Demanding Requirements of Civil Aviation, Claude Loisy, 

ESTEC, ESA. 

Most Probable Satellite Communication Operating Concept for ECAC and other regions of 

the world, EUROCONTROL, Draft edition, May 2002. 

3G/UMTS/CDMA References 

Second Airborne Trials with the Siemens 3G Testbed, EUROCONTROL, September 2002. 

Study into Modifying the Siemens 3G Testbed for Airborne Trials, EUROCONTROL, August 

2002. 

3rd Generation Partnership Project (3GPP) Standards, 3GPP. 

WCDMA Gets Set For TakeOff in Air Transport, 3G Newsroom, 15 th March 2002. 

Gatelink 

Integrated Information Systems, Rockwell Collins, White Paper. 

Page 341

Study of Wireless Airport Communication Systems (WACS) – Inventory of Existing 

Wireless Systems and Related Activities, COM-2-30-1100, Edition 1.2, February 2000, 

EUROCONTROL . 

Study of Wireless Airport Communication Systems (WACS) – User Requirements, COM-2- 

30-1300, Edition 1.2, February 2000, EUROCONTROL. 

Study of Wireless Airport Communication Systems (WACS) – Spectrum Issues, COM-2- 


Study of Wireless Airport Communication Systems (WACS) – Report on Technical 

Analysis, COM-2-30-1600, Edition 1.2, February 2000, EUROCONTROL. 

Study of Wireless Airport Communication Systems (WACS) – Costs and Benefits, COM-2- 


Study of Wireless Airport Communication Systems (WACS) – Synthesis Report, COM-2- 


Wireless LAN Medium Access Control (MAC) and Physical Layer (PHY) Specifications, 

IEEE 802.11. 

Wireless LAN Medium Access Control (MAC) and Physical Layer (PHY) Specifications: 

High Speed Physical Layer (PHY) in the 5 GHz Band, IEEE 802.11a. 

Wireless LAN Medium Access Control (MAC) and Physical Layer (PHY) Specifications: 

Higher Speed Physical Layer (PHY) Extension in the 2.4 GHz band, IEEE 802.11b. 

Broadband Radio Access Networks (BRAN); HIgh PErformance Radio Local Area Network 

(HIPERLAN), Type 2; Requirements and architectures for wireless broadband access, 

ETSI. 

Compatibility studies related to the possible extension band for HIPERLAN at 5 GHz, 

Report 72, ERC. 

Broadband Radio Access Networks (BRAN); HIPERLAN Type 2; System overview, ETSI. 

Radio Equipment and Systems (RES); Wideband transmission systems; Technical 

characteristics and test conditions for data transmission equipment operating in the 2.4 

GHz ISM band and using spread spectrum modulation techniques, ETS 300 328, ETSI . 

Boeing Connexion 

Connexion by Boeing - Broadband Satellite Services for Aircraft, Michael de La Chapelle et 

al., Boeing Space & Communications, July 2001 . 

Connexion by Boeing - Broadband Satellite Services for Aircraft, AEEC Data Link Users 

Forum, Boston, USA, July 2001, Al Burgemeister, The Boeing Company . 

Boeing's inflight Internet service gets FAA certification, Puget Sound Business Journal, 

May 2002 

United Kingdom Grants License for Connexion by Boeing, CNN Money, July 2002. 

General 

Roadmap for the implementation of data link services in European Air Traffic Management 

(ATM): Technology Assessment, European Commission contract B2001/B2- 

7020D/Si2.330694, Document P167D2020 Version 5.0, 28 February 2003. . 

Roadmap for the implementation of data link services in European Air Traffic Management 

(ATM): Application Assessment, European Commission contract B2001/B2- 

7020D/Si2.330694, Document P167D1030 Version 2.0, 30 October 2002. . 

Page 342

An economic study to review spectrum pricing, Indepen, Aegis and Warwick Business 

School, February 2004. . 

Analyse Options For Initial Air/Ground Data Networks: Executive Summary 

COM.ET2.ST15.0000, EUROCONTROL, 1998 

Page 343

Annex 7-4 Maritime Communications References – Chapter 6 

• United Kingdom Table of Radio Frequency Allocations, RA365 

http://www.ofcom.org.uk/static/archive/ra/publication/ra_info/ra365.htm 

• UK Communications Act 2003 (and EC Communications Directives) 

• An economic study to review spectrum pricing, Indepen, Aegis and Warwick 

Business School, February 2004. 

• ITU Radio Regulations 

• CEPT Recommendation T/R 70-03 concerning SRDs 

• Various Directives of the European Union in particular 1995/5/EC (R&TTE) and 

1996/98/EC (MED) 

• Commission Decision on the Application of 3(3)(e) of 1999/5/EC 

• 2002 List of Registered UK Fishing Vessels – Defra 

• Positioning using a differential GPS in near shore tidal waters – Ince, Edwards 

and Parker – University of Newcastle 

• Cave 2002 Review of Radio Spectrum Management in the UK 

• Airworthiness Information Leaflet – Guidance on Testing Emergency Location 

Transmitters – UK CAA 

• Inception Study to support the development of a business plan for Galileo 

programme – PricewaterhouseCoopers, Belgium – Study contract ETU-B6613- 

E4-PWC-2001-S12.321824 

• Verification and validation of Galileo system and services – Naddeo, Tossaint 

and Strodl 

• High Data Rate HF Communication System – Gangully, Jovancevic, Parker and 

Brown – Center for Remote Sensing Inc. 

Page 344

ANNEX 8 Countries in Receipt of Questionnaire 

COUNTRY Aero, Mar or Reg 

import 

EU15 All 

Notes 

USA All No1 Aero, No 12 

maritime nation 

Canada Aero, Reg 

Panama Mar No 1 maritime nation 

Liberia Mar No 2 maritime nation 

Bahamas Mar No 4 maritime nation 

Malta Mar No 5 maritime nation 

Cyprus Mar No 6 maritime nation 

Singapore Mar, Aero No 7 maritime nation 

China Mar, Aero Including Hong Kong 

Japan All 

Australia Aero, Reg 

New Zealand Reg 

Bermuda UK Dependency 

Norway Aero, Mar Part SAS, No 10 

maritime nation 

Korea Aero, Mar No 15 maritime nation 

Turkey Mar No 20 maritime nation 

South Africa Reg Important regional 

country 

UAE Aero Important regional 

country 

Brazil Important regional 

country 

Russian Federation Important regional 

country 

Note In addition fees and charges information from Lebanon and Pakistan were 

incorporated into the report 

Page 345

ANNEX 9 The Questionnaire 

In order to conserve paper and the size of the document, the questionnaire is presented in the 

form of an embedded word document. 

It can be accessed by clicking the appropriate icon below 

DESCRIPTION EMBEDDED FILE 

Basic Questionnaire 

C:\Questionnair.doc 

Page 346

FINAL REPORT - Stakeholders - Ofcom

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