FINAL REPORT - Stakeholders - Ofcom
FINAL REPORT - Stakeholders - Ofcom
FINAL REPORT - Stakeholders - Ofcom
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4.2.3.9 Possible Overall Spectrum Efficiency Improvements<br />
<strong>Ofcom</strong> should initiate a market survey to determine the extent of usage of such<br />
equipment and identify potential frequencies that could be used in the UK, if such are<br />
available and required, in order to bring the usage of such equipment into a licensed<br />
framework.<br />
4.3 Shipborne<br />
4.3.1 MSR (Maritime Surveillance Radar)<br />
4.3.1.1 Technology Description<br />
The description given in section 4.2.1.1 concerning ground-based radars applies equally<br />
here and has not been duplicated for the purpose of brevity.<br />
The requirements for ship-borne radars vary; many vessels are required by the IMO<br />
convention on safety of life at sea to carry two radars. This requirement can be met by<br />
fitting two 9 GHz radars or one 9 GHz radar and one either 3 GHz or 5 GHz radar. The<br />
band 9200 – 9500 MHz is by far the most commonly employed, but the 3 GHz band is<br />
used on ships which encounter sleet and snow on a regular basis, as it gives better<br />
results in these conditions due to a reduction in the effects of clutter relative to the 9 GHz<br />
band. A low-power version of the 9 GHz radar is fitted to a large number of yachts and<br />
pleasure vessels.<br />
4.3.1.2 Operational Requirements<br />
IMO Operational Requirements<br />
The IMO sets out the operational performance criteria which maritime radars shall meet.<br />
This standard sets limits for accuracy of measurement and minimum and maximum range<br />
over which the radar must produce the specified level of accuracy.<br />
The practical implication of the range requirement translates into the need to mount the<br />
radar head at least 15 metres above sea level. It is common practise, however that the<br />
electronics associated with the radar (including the RF modules) are on the deck. This<br />
has a direct impact on the technical specifications of the radar. The short delay in sending<br />
the transmitted signal up 15 metres of cable, and waiting the same time for the received<br />
reflections, together with the speed at which it is possible to switch between transmit and<br />
receive, plus the minimum range requirement (i.e. how close to a vessel the radar must<br />
function) of 40 metres has a direct impact on the pulse-width, which must remain short in<br />
order to meet the IMO operational requirements. Keeping the pulse short implies a wider<br />
bandwidth.<br />
GMDSS Requirements<br />
The Global Maritime Distress and Safety System (GMDSS) is a maritime communication<br />
system for all vessels. However, it is not just for emergencies and can be used for vesselto-vessel<br />
routine communications. Commercial vessels over 300 gross tonnage and<br />
certain smaller fishing vessels, including some fishing boats are mandated to carry<br />
GMDSS equipment. Most of the well-known offshore yacht races now insist yachts are<br />
GMDSS equipped too. The GMDSS requirements split the oceans into 4 different kinds of<br />
area, each dependent on distance from the shore, and density of maritime traffic. The sea<br />
area a vessel is to operate in, determines which of the elements of the GMDSS that it<br />
must carry.<br />
There are several elements that make up the total GMDSS communications package<br />
including Digital Selective Calling (DSC) via radio. The other elements include satellite<br />
communications, Navtex for weather and navigation information, Search and Rescue<br />
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