Saab R5 SUPREME AIS Operation & Installation Manual

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Saab R5 SUPREME AIS Operation & Installation Manual Manual pdf 20 page image

R5 SUPREME AIS SystemINSTALLATION7000 118-300, A3 Page 20 Tighten the anti-vibration glands so that the cables are secured. Connect the cables to the terminal blocks. Fix the lid to the box casing.3.10 Mount the VHF AntennaThe R5 SUPREME Transponder, like any other ship borne transceiver operating in the VHFmaritime band, may cause interference to a ship‟s VHF radiotelephone. Because AIS is a digitalsystem, this interference may occur as a periodic (e.g. every 10 second) soft clicking sound on aship‟s radiotelephone. This effect may become more noticeable when the VHF radiotelephoneantenna is located close to the AIS VHF antenna and when the radiotelephone is operating onchannels near the AIS operating channels (e.g. channels 27, 28 and 86).Attention should be paid to the location and installation of different antennas in order to obtain thebest possible efficiency. Special attention should be paid to the installation of mandatoryantennas like the AIS antennas.So, installing the AIS VHF antenna is also a crucial part of the system installation. How andwhere you install your AIS VHF antenna and cable will affect its efficiency.3.10.1 VHF Antenna LocationLocation of the mandatory AIS VHF antenna should be carefully considered. Digitalcommunication is more sensitive than analogue/voice communication to interference createdby reflections in obstructions like masts and booms. It may be necessary to relocate the VHFradiotelephone antenna to minimize the interference effects. Installing the VHF antenna forAIS on a vessel is a compromise between the following items: Antenna type Antenna separation Clear view of the horizon Antenna height3.10.1.1 Antenna TypeThe AIS VHF antenna should have Omni directional vertical polarization providing unitygain.3.10.1.2 Antenna SeparationAIS transponders use simplex channels at frequencies on the high side of the marinemobile band (AIS channel A = 2087, 161.975 MHz, and AIS channel B = 2088, 162.025MHz). These channels are close to the duplex channels used for shore to ship marinecommunication. The AIS VHF antenna should be separated as much as possible from thevoice VHF installations used for main communication to avoid unnecessary interference.There should not be more than one antenna on the same level. The AIS VHF antennashould be mounted directly above or below the ship‟s primary VHF radiotelephone antenna,with no horizontal separation and with a minimum of 2 meters vertical separation. If it islocated on the same level as other antennas, the distance apart should be at least 10meters.The AIS VHF antenna should be installed safely away from interfering high-power radiatingsources like radar and other transmitting radio antennas, preferably at least 3 meters awayfrom and out of the transmitting beam.