ANNEX 4
LIAISON STATEMENT FROM IMO TO ITU-R
Working Party 8B
1 The IMO Sub-Committee on Safety of Navigation, at its forty-fourth session (20 to 24 July 1998), noted the amended question Q.216/8 concerning the technical compatibility of radionavigation systems and radiolocation systems operating in the band 2.9-3.3 GHz.
2 The Sub-Committee wishes to inform the Working Party that this band is an important band for maritime radars involving a SOLAS carriage requirement for many ships. Maritime radars operate on a nominal frequency Of 3.05 GHz and it will be very difficult to change to another frequency, as well as requiring a considerable time span. There are also large numbers of fixed RACONS operating around coastlines.
3 In the interests of safety at sea IMO has recently improved the Performance Standards for maritime radars which has created a need for the use of shorter pulse widths. This in time may increase the out of band emissions produced by marine radars which will fall in the band 2.9-3.3 GHz and which need to be taken into account in compatibility studies with other radars.
4 The Sub-Committee further noted Recommendation ITU-R SM.329-7 on spurious emissions. Two categories are included - Category A which applies to maritime mobile radars Category B which may apply to maritime fixed radar for Vessel Traffic Services (VTS). The Sub-Committee would like to point out that VTS radars are maritime mobile radars adapted as appropriate to the VTS environment. It is therefore illogical that maritime mobile radars, used for safety purposes, meeting the Category A limits of 60 dB (- 13 dBm) when used in a VTS should be required to meet Category B limits of 100 dB (- 30 dBm). Enforcement of such limits would lead to a significant increase in costs of VTS systems.
