Mount The Gps Or Dgps Navigation Antenna - Saab R5 Supreme Operation & Installation Manual

2.5

Mount the GPS or DGPS Navigation Antenna

The R4 Navigation Sensor should be connected to the included antenna, which in the GPS
configuration is a MGA-2 GPS antenna and in the DGPS configuration is a MGL-4
combined GPS/Beacon antenna.
Attention should be paid to the location and installation of the different antennas on the ship
in order to obtain the best possible signal reception. Installation of the Navigation Sensor's
antenna is a crucial part of the system installation. How and where you install your antenna
and cable will greatly affect its sensing efficiency.
2.5.1 Antenna Location
Mount the MGA-2 or MGL-4 antenna at a location with a clear, unobstructed view of
the sky. For best beacon reception performance, mount the MGL-4 antenna so that the
center of the black gasket is at least 8 cm (3 in) above any metal surface.
Local noise generated by your vessel or surroundings may affect your navigation
system performance. To minimize this impact, you should locate the antenna outside
the path of any radar beam, away from any transmitting antennas, and away from any
other sources of interference such as motors, solenoids and other electronics. Do not,
however, mount the antenna in the top of a mast or tower, as this may degrade the
COG and SOG readings.
The MGA-2 and MGL-4 uses a 1-14-UNS thread for mounting. Mount the antenna on a
standard US 1‖ 14 thread pipe or other standard antenna mount (not included).
Note: Antennas threaded onto a mount should be tightened only by hand. Do not
tighten the antenna by turning on the antenna cover, instead hold the mounting shaft
located at the bottom of the antenna and tighten by hand. Do not thread the pipe
deeper than ¾ into the antenna. Do not use tools to install the antenna on the pipe as
this may cause damage. Damage caused by over tightening is not covered by
warranty.
Note: Once the system has been correctly mounted and connected, it is possible to
monitor the R4 Navigation Sensor receiving performance via the graphical interface of
the R5 SUPREME CDU. This information can be used to locate the optimum
placement of the antenna. This is further described in section 5.11.3.
2.5.2 Cabling
The maximum allowable cable loss is 18 dB for the MGA-2 and MGL-4 antennas. The
maximum cable length depends on the attenuation of the cable and the chosen
antenna.
Double shielded coaxial cable is recommended. The coaxial cable should be routed
directly between the antenna and the R4 Navigation Sensor 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 any AIS VHF antenna cable. A
separation of one meter or more is recommended to avoid interference due to RF-
coupling. Crossing of antenna cables should be done at 90 degrees to minimize
magnetic field coupling.
The table below gives recommendation on cables that can be used for the GPS-
antenna connections. Due to the high frequency it's important that the attenuation in
the cable is low for the specific frequency (1.5 GHz).
7000 118-301, A3
R5
SUPREME - Navigation System
INSTALLATION
Page 25