NavCom SF-2050 Rev.G - Manual (Page 45)

SF-2050 User Guide – Rev. G
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.
9 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.
9 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).
9 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, 098° West,
142
° West, 025° East, 109° East, and
143.5
° East. An inclination and bearing estimation
tool is available on NavCom’s website to aid in
determining potential obstructions to StarFire™
signal.
L-Band Antenna (SF-2050R Only)
The separate L-band antenna for the SF-2050R 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 GPS antenna. On marine
platforms with many antenna systems, it is better to
locate the standard GPS antenna closer to the
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