NavCom SF-2040 Rev.F - Manual (Page 75)

SF-2040 User Guide – Rev. F
optimized for a dual-frequency system such as
StarFire™ in which dual-frequency ionospheric
measurements are available at both the reference
receivers and the user receivers. It is the use of dual-
frequency receivers at both the reference stations
and the user equipment together with the advanced
processing algorithms, which makes the exceptional
accuracy of the StarFire™ system possible.
Creating the corrections is just the first part. From our
two processing centers, the differential corrections
are then sent to the Land Earth Station (LES) for
uplink to L-Band communications satellites. The
uplink sites for the network are equipped with
NavCom-built modulation equipment, which
interfaces to the satellite system transmitter and
uplinks the correction data stream to the satellite that
broadcasts it over the coverage area. Each L-Band
satellite covers more than a third of the earth.
Users equipped with a StarFire™ precision GPS
receiver actually have two receivers in a single
package, a GPS receiver and an L-Band
communications receiver, both designed by NavCom
for this system. The GPS receiver tracks all the
satellites in view and makes pseudorange
measurements to the GPS satellites. Simultaneously,
the L-Band receiver receives the correction
messages broadcast via the L-Band satellite. When
the corrections are applied to the GPS
measurements, a position measurement of
unprecedented real time accuracy is produced.
Reliability
The entire system meets or exceeds a target
availability of 99.99%. To achieve this, every part of
the infrastructure has a built-in back-up system.
All the reference stations are built with duplicate
receivers, processors and communication interfaces,
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