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1001001-2EN A2 Product Manual 2_0
separate signal cable channels/tubes, and at least 10 cm 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 to the characteristic impedance of the cable. The minimum bend radius should be 5 times
cables should take place at right angles (90°). Coaxial cables should not be exposed to sharp bends, which
may lead to changes to the characteristic impedance of the cable. The minimum bend radius should be 5 times
the cables outside diameter.
Grounding
Coaxial down-leads must be used for all receiving antennas, and the coaxial screen should be connected to
the ground at one end.
Coaxial down-leads must be used for all receiving antennas, and the coaxial screen should be connected to
the ground at one end.
3.5
Mount the NAUTICAST A2 GPS Antenna
The NAUTICAST A2 shall be connected to a GPS antenna type Procom GPS-4 (1001022), Nauticast Standard
GPS antenna (3001002) or to a combined GPS/VHF antenna AC Marine VHF/GPS-2 (1001027). 5V DC is
supplied through the antenna lead for the antenna preamplifier.
GPS antenna (3001002) or to a combined GPS/VHF antenna AC Marine VHF/GPS-2 (1001027). 5V DC is
supplied through the antenna lead for the antenna preamplifier.
Please note the Compass Safe Distances in section 6.3 “Transponder Environment”.
If the combined AC Marine GPS/VHF antenna is used the diplexer unit shall be installed in an indoor
If the combined AC Marine GPS/VHF antenna is used the diplexer unit shall be installed in an indoor
environment.
Attention should be paid to the location and installation of the different antennas on the ship in order to obtain
Attention should be paid to the location and installation of the different antennas on the ship in order to obtain
the best possible efficiency. How and where the GPS antenna and cable is installed will greatly affect its sensing
efficiency.
efficiency.
3.5.1 GPS Antenna Location
The GNSS antenna must be installed where it has a clear view of the sky, so that it accesses the horizon freely
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.
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,
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.
If a DGNSS system is included or connected to the AIS system, the installation of the antenna should be
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.
3.5.2 GPS Cabling
3.5.2 GPS Cabling
The gain of the GPS antenna built-in pre-amplifier shall match the cable attenuation. The resulting installation
gain (pre-amplifier gain minus cable attenuation) shall be within 0 to 26 dB. A minimum value of 10 dB is
gain (pre-amplifier gain minus cable attenuation) shall be within 0 to 26 dB. A minimum value of 10 dB is
recommended for optimum performance.
A double shielded coaxial cable is recommended. The coaxial cable should be routed directly between the GPS
antenna and the NAUTICAST A2 GPS connector in order to reduce electromagnetic interference effects. The
A double shielded coaxial cable is recommended. The coaxial cable should be routed directly between the GPS
antenna and the NAUTICAST A2 GPS connector in order to reduce electromagnetic interference effects. The
cable should not be installed close to high-power lines, such as radar or radio transmitter lines or the AIS VHF
antenna cable. A separation of 1 meter or more is recommended to avoid interference due to RF-coupling.
antenna cable. A separation of 1 meter or more is recommended to avoid interference due to RF-coupling.
Crossing of antenna cables should be done at 90 degrees to minimise magnetic field coupling.
The table below gives recommendation on cables that can be used for the Transponder GPS-antenna
connections, the cables used should always be of marine approved type. Due to the high frequency it’s
The table below gives recommendation on cables that can be used for the Transponder GPS-antenna
connections, the cables used should always be of marine approved type. Due to the high frequency it’s
important that the attenuation in the cable is low for the specific frequency (1.5 GHz).
Type
Attenuation @ 1.5
GHz (dB/m)
GHz (dB/m)
(mm)
Weight (kg/100m)
RG 58
0.9
5
3.7
RG 400
0.6
4.95
6.3
RG 223
0.6
5.40
5.5
RG 214
0.35
10.8
18.5
RG 225
0.3
10.9
23.3
Table 3 – GPS Antenna Cables
For optimum performance approximately +10dB gain should be available when the cable attenuation has been
subtracted from the GPS-antenna preamplifier gain. The net gain shall not exceed +26dB.
subtracted from the GPS-antenna preamplifier gain. The net gain shall not exceed +26dB.