NavCom SF-2040 Rev.F - Manual (Page 45)

SF-2040 User Guide – Rev. F
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
° West. An inclination and bearing
estimation tool is available on NavCom’s website
to aid in determining potential obstructions to
StarFire™ signal.
Block Diagram
The SF-2040 has two user configurable physical
communications ports and several internal logical
communications ports. The Com ports are described
in the next section. To aid in distinguishing these
ports, please refer to the block diagram below.
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