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Section 5 Principle
Differential GPS (DGPS)
The differential GPS comprises a reference station with its position(latitude
and longitude) accurately known, a beacon station for radio broadcasting of
DGPS correction data, and user-owned GPS sensor equipped with a differential
correcting function.
The GPS sensor is used to fix the position of the reference station whose
position is accurately known and to compare this with the actual reference station
position to get range errors. The range errors are transmitted to the beacon station
as the DGPS correction data and are broadcast from the beacon station to the
user. This DGPS correction data is received by the user-owned beacon receiver,
and is sent to the GPS sensor. The GPS sensor calculates its own position by
adding the correction data to the actual data transmitted from the satellites.
Compared with the fixed positioning provided by existing GPS sensors, the
DGPS system calculates the position with a very small error not exceeding 10%
of the measure.
DGPS System
Figure 5-7
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