ACR Electronics NAUTICAST SOLAS AIS Installation Manual

Also see for NAUTICAST: Installation manual Installation manual Manual User manual User manual

Contents

ACR Electronics NAUTICAST SOLAS AIS Installation Manual Manual pdf 33 page image

Installation Manual 29 Y1-03-0204 Rev.HAll outdoor connectors on the coaxial cables should be fitted with preventive isolation, suchas shrink-stocking with silicone to protect the antenna cable against water penetration.Coaxial cables should be installed in separate signal cable channels/tubes, and at least 10cm away from any power supply cables. Crossing of cables should take place at right angles(90°). Coaxial cables should not be exposed to sharp bends, which may lead to changes tothe characteristic impedance of the cable. The minimum bend radius should be 5 times thecables outside diameter.GroundingCoaxial down-leads must be used for all receiving antennas, and the coaxial screen shouldbe connected to the ground at one end.3.11.2 GNSS Antenna installationA Class A AIS must be connected to a GNSS antenna.LocationThe GNSS antenna must be installed where it has a clear view of the sky, so that it accessesthe horizon freely through 360°, with a vertical observation of 5 to 90 degrees above thehorizon. Small diameter obstructions, such as masts and booms, do not seriously impairsignal reception, but such objects must not eclipse more than a few degrees of any givenbearing.The antenna must be located at least three meters away from, and out of the transmittingbeam of high-power transmitters (S-Band Radar and/or Inmarsat systems). This includes theship’s own AIS VHF antenna, if it is designed and installed separately. See also sample forantenna layout in Installation Manual Appendix 8.2 (Drawings)If a DGNSS system is included or connected to the AIS system, the installation of theantenna should be undertaken in accordance with IEC 61108-4, Edition 1.CablingTo achieve optimum performance, the gain of the antenna pre-amplifier should match thecable attenuation. The resulting installation gain (pre-amplifier gain - cable attenuation)should be within 0 to 10 dB (RG214 at GPS attenuation per meter of app. 0,35 dB/m (45m =15,75dB); GPS frequency app. 1,2GHz).The coaxial cable between the antenna and the AIS ship borne station connector should berouted directly, in order to reduce electromagnetic interference. The cable should not beinstalled close to high-power lines, such as radar or radio-transmitter lines, or near the AISVHF antenna cable. A space of one meter or more is recommended in order to avoiddegradation due to RF-coupling. Crossing of antenna cables should take place at 90 degrees,to minimize magnetic field coupling.AttenuationAs described above, the resulting installation gain should be between 0 to 10 dB. If theinternal GPS receiver will be overloaded with more than 18dB, then it could be damaged.