Specifications

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6.2 Cabling
All outdoor installed connectors on coaxial cables should be fitted with preventive isolation such as
vulcanizing tape to protect against water penetration into the antenna cable.
Coaxial cables should be installed in separate signal cable channels/tubes and at least 10 cm away from
power supply cables. Crossing of cables should be done at right angles (90°). The minimum bend radius of
the coaxial cable should be 5 times the cable's outer diameter.
The cables should be kept as short as possible to minimize signal attenuation.
The type of cables used onboard vessels should be:
o
Halogen free
o
Fire resistant or Flame retardant type
o
Low smoke
6.2.1 GPS antenna
The table below gives recommendations on cables that can be used for the GPS antenna
connections:
Type
Attenuation
@1.5 GHz
(dB/100 m)
Remark
RG58
90
Default for use if length < 20 m and
antenna = An156
RG214 35
If combined GPS/VHF antenna from either AC-Marine, Procom
or Comrod is used, this or better can be used
RG225
30
Cable with lower loss recommended for cable runs >30
meters
For optimum performance of the transponder approximately +10 dB gain should be available when the
cable attenuation has been subtracted from the GPS antenna preamplifier gain. Note that Procom
AIS2/GPS and Comrod AC17-AIS are combined VHF/GPS antennas and additional attenuation from
connectors / diplexer must be taken in consideration. Some examples below:
Cable Type Antenna Preamplifier Gain
(dB/100 m)
Recommended cable length (m)
RG58
AN156
30
<20
RG214
AN156
28
10-30
Comrod AC17-AIS
20
10-20
AC Marine VHF/GPS-B
18
10-20
RG225
AN156
28
10-40
Comrod AC17-AIS
20
10-30
AC Marine VHF/GPS-B
18
10-30