NavCom SF-3050 Rev.I - Manual (Page 113)

SF-3050 GNSS Product User Guide – Rev I
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Do not place the antenna too close to other active antennas. The wavelength of L5 is
0.255m and G1 is 0.187m. The minimum acceptable separation between antennas is 1m
(39 in), which provides 5.9dB of isolation. For 10 dB of isolation, separate the GNSS
antennas by 2.55m, and for 13dB of isolation (recommended) separate the antennas by
5.1m.
Active antennas (those with LNA’s or amplifiers) create an electrical field around the
antenna. These radiated emissions can interfere with other nearby antennas. Multiple
GNSS antennas in close proximity to each other can create multipath and oscillations
between the antennas. These add to position error or the inability to process the satellite
signals.
Most antenna’s have better gain when the satellite is high in elevation. Expect tracking
performance to fade as the satellite lowers in elevation. It is not unusual to see 10dB
difference in antenna gain (which translates into signal strength) throughout the entire
elevation tracking path.
Map obstructions above the horizon using a compass and inclinometer. Use satellite
prediction software with a recent satellite almanac to assess the impact on satellite
visibility at that location
(available on NavCom’s web site).
A clear line of sight between the antenna and the local INMARSAT satellite is required to
track the StarFire signal. INMARSAT satellites are geo-synchronized 35,768kms above
the Equator, currently at Longitudes 15.5

West, 97.65

West, 142

West, 025

East,
109

East, and 178

East. An inclination and bearing estimation tool is available on
NavCom ’s website to aid in determining potential obstructions to StarFire signal.
GNSS Sensor
Mount the SF-3050 GNSS sensor on a flat surface. Shock isolators suitable for 0.50kg
(1.1 lbs) may be necessary for environments with high vibration, i.e., earth-moving
equipment or aircraft.
Do not place the sensor in a confined space or where it may be exposed to excessive
heat, moisture, or humidity.

MED Compass Safe Distance: The SF-3050 receiver may not be installed
closer than 250mm to the ship’s compass.
The SF-3050 can be installed in a backpack for mobile surveying applications.

There are no user serviceable parts inside the SF-3050 GNSS sensor.
Removing the screws that secure the front end and rear end plates will
void the equipment warranty.

If the receiver will be used or transported above 40,000 ft (12.2. km), it
must be located in a pressurized compartment.