ACR Electronics Nauticast 2607 - Manual (Page 33)

Installation Manual 29 Y1-03-0204 Rev.K
Coaxial down-leads must be used for all receiving antennas, and the coaxial screen should
be connected to the ground at one end.
3.11.2 GNSS Antenna installation
A Class A AIS must be connected to a GNSS antenna.
Location
The GNSS antenna must be installed where it has a clear view of the sky, so that it accesses
the horizon freely through 360°, with a vertical observation of 5 to 90 degrees above the
horizon. Small diameter obstructions, such as masts and booms, do not seriously impair
signal reception, but such objects must not eclipse more than a few degrees of any given
bearing.
The antenna must be located at least three meters away from, and out of the transmitting
beam of high-power transmitters (S-Band Radar and/or Inmarsat systems). This includes the
ship‟s own AIS VHF antenna, if it is designed and installed separately. See also sample for
antenna layout in Installation Manual Appendix 8.2 (Drawings)
If a DGNSS system is included or connected to the AIS system, the installation of the
antenna should be undertaken in accordance with IEC 61108-4, Edition 1.
Cabling
To achieve optimum performance, the gain of the antenna pre-amplifier should match the
cable attenuation. The NAUTICAST can be equipped with two different types of internal GPS
receivers. It differs between „Jupiter‟ and „µBlox‟
The resulting installation gain for Jupiter (pre-amplifier gain - cable attenuation) should be
within 0 to 10 dB and for µBlox 5 to 15 dB. RG214 as GPS antenna cable has an 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 be
routed directly, in order to reduce electromagnetic interference. The cable should not be
installed close to high-power lines, such as radar or radio-transmitter lines, or near the AIS
VHF antenna cable. A space of one meter or more is recommended in order to avoid
degradation due to RF-coupling. Crossing of antenna cables should take place at 90 degrees,
to minimize magnetic field coupling.