FINAL REPORT - Stakeholders - Ofcom

� 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)
6.11.1 Frequency Allocations (international)
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.
6.11.2 Technology Description
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.
6.11.3 Operational Requirements
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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