NavCom SF-3050 Rev.B - Manual (Page 103)

SF-3050 User Guide – Rev B
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.
Tall L-band Antenna (High Latitude L-Band
Antenna Kit option)
The separate Tall L-band antenna is used in high
latitude applications and most frequently on marine
vessels. This is an active antenna, meaning it has a
built-in LNA. Therefore, this antenna should have
good isolation from other near-frequency antennae.
The best practice is to follow the same precautions as
the standard GNSS antenna. On marine platforms
with many antenna systems, it is better to locate the
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