NavCom SF-2040 Rev.E - Manual (Page 47)

SF-2040 User Guide - Rev. E
constellation. This proprietary wide area DGPS
( WADGPS ) algorithm is 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.
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