R5 SOLID AIS System
INSTALLATION
7000 118-200, C2 Page 17
Figure 8 – Combined VHF / GPS Antenna – AC Marine
3.5 Mount the R5 SOLID Transponder’s VHF antenna
The R5 SOLID, like any other ship borne transceiver operating in the VHF maritime band,
may cause interference to a ship’s VHF radiotelephone. Because AIS is a digital system,
this interference may occur as a periodic (e.g. every 10 second) soft clicking sound on a
ship’s radiotelephone. This effect may become more noticeable when the VHF
radiotelephone antenna is located close to the AIS VHF antenna and when the
radiotelephone is operating on channels 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 the best possible efficiency. Special attention should be paid to the installation of
mandatory antennas like the AIS antennas.
So, installing the AIS VHF antenna is also a crucial part of the system installation. How
and where you install your AIS VHF antenna and cable will affect its efficiency.
3.5.1 VHF Antenna Location
Location of the mandatory AIS VHF antenna should be carefully considered. Digital
communication is more sensitive than analogue/voice communication to interference
created by reflections in obstructions like masts and booms. It may be necessary to
relocate the VHF radiotelephone antenna to minimize the interference effects. Installing
the VHF antenna for AIS on a vessel is a compromise between the following items:
Antenna type
Antenna separation
Clear view of the horizon
Antenna height
3.5.1.1 Antenna Type
The AIS VHF antenna should have Omni directional vertical polarization providing unity
gain.
3.5.1.2 Antenna Separation
AIS transponders use simplex channels at frequencies on the high side of the marine
mobile band (AIS channel A = 2087, 161.975 MHz and AIS channel B = 2088, 162.025
MHz). These channels are close to the duplex channels used for shore to ship marine
communication. The AIS VHF antenna should be separated as much as possible from
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