Comar Systems 001-1019, User Manual

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CSB200-S
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8.1 GPS Antenna
The GPS antenna used for a Class ‘B’ AIS device must be a dedicated antenna, i.e. not shared with
any other GPS receiver.
Any NMEA GPS positional sentences transmitted as data from other equipment and connected to
the NMEA ports of the CSB200-S will not be used for AIS transmission.
The GPS antenna to be used must be of the active type, i.e. it should incorporate a low noise
amplifier (LNA) and be suitable for marine shipboard applications (index of protection, ruggedness,
means of mounting
etc. ) A GPS antenna should be selected so that there is a minimum total gain of
25 dB available at the antenna connector on the rear of the CSB200-S.
Installation of the GPS antenna is critical for the performance of the built in GPS receiver which is
used for timing of the transmitted time slots and for the supply of navigational information should
the main navigational GPS fail.
We strongly recommend that:
●
The GPS antenna is mounted in an elevated position and free of shadow effect from the
ship’s superstructure.
●
The GPS antenna has a free view through 360 degrees with a vertical angle of 5 to 90 degrees
above the horizon.
●
As the received GPS signal is very sensitive to noise and interference generated by other
onboard transmitters, ensure that the GPS antenna is placed as far away as possible from
RADAR, Inmarsat® and Iridium® transmitters and ensure the GPS antenna is free from direct
view of the RADAR and the Inmarsat beam.
●
It is important that the MF/HF and other VHF transmitter antennas are kept as far away as
possible from the GNSS antenna. It is good practice never to install a GPS antenna within a
radius of 5 metres from these antennas.
8.2 VHF Antenna
The CSB200-S with built-in Antenna Splitter can share a single VHF antenna with a VHF
radiotelephone. The VHF antenna should meet the following requirements:
●
It must be suitable for marine shipboard applications (index of protection, ruggedness,
means of mounting,
etc .)
●
It should be omni-directional and vertically polarised with unity gain (0 dB) with a bandwidth
sufficient to maintain VSWR <1.5 over the frequency range 156 -163 MHz. As a minimum
the 3 dB bandwidth must cover the two AIS channels and the DSC Channel.
●
It should be mounted with at least a two metre vertical separation distance from any other
VHF antenna used for speech or DCS communication.