R5 SOLID AIS System
INSTALLATION
7000 118-200, C2 Page 19
Coaxial cables should not be exposed to sharp bends, which may lead to a change of
the characteristic impedance of the cable. The minimum bending radius should be 5
times the cable's diameter.
All outdoor installed connectors should be weather proofed, e.g. with shrink tubing,
watertight seal tape or butyl rubber tape and plastic tape sealing, to protect against
water penetration into the antenna cable.
Secure the cable properly close to the cable ends.
3.5.4 VHF Cable Grounding
Coaxial down-leads must be grounded. The coaxial shielding screen should be
connected to ground at one end.
3.6 Mount the R5 SOLID GPS Antenna
The R5 SOLID shall be connected to a GPS antenna type MA-700, AT575-68 or a
combined AC Marine GPS/VHF antenna. 5V DC is supplied through the antenna lead for
the antenna preamplifier.
Please note the Compass Safe Distances in section 6.3 “Environmental”.
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 the best possible efficiency. Special attention should be paid to the
installation of mandatory antennas like the AIS antennas.
So, installation of the GPS antenna is a crucial part of the system installation. How and
where you install your GPS antenna and cable will greatly affect its sensing efficiency.
3.6.1 GPS Antenna Location
The GPS antenna must be installed where it has a clear view of the sky. The objective
is to see the horizon freely through 360 degrees with a vertical observation of 5 to 90
degrees above the horizon. Small diameter obstructions, such as masts and booms, do
not seriously degrade signal reception, but such objects should not eclipse more than a
few degrees of any given bearing. Do not mount the antenna in the top of a mast or
tower, as this may degrade the COG and SOG readings.
Locate the GPS antenna at least 3 meters away from and out of the transmitting beam
of high-power transmitters such as S-Band Radar (typically 15° vertically from the
array’s centre point) and/or Inmarsat systems (A, B, C, or M; typically 10º from the
array’s centre point in any of the possible transmitting directions).
Locate the GPS antenna at least 3 meters away from HF or VHF radios or their
antennas. This includes the ship’s own AIS VHF antenna if it is designed and installed
separately.
3.6.2 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 recommended for optimum
performance.
Double shielded coaxial cable is recommended. The coaxial cable should be routed
directly between the GPS antenna and the R5 SOLID GPS connector in order to
reduce electromagnetic interference effects. The cable should not be installed close to