Differential GPS Operation With Multiple Ground Reference Stations

Wang Tang, Newton Johnson, Jack Graff

Abstract:	A typical differential GPS (DGPS) configuration consists of a ground reference receiver placed at a surveyed location to estimate pseudo-range error for each visible satellite. The estimated errors are then uplinked to other receivers in the vicinity for the use in pseudo-range measurement compensation. The DGPS operation offers significant position accuracy improvement if both reference and participating receivers are close to each other. However, the DGPS accuracy degrades as the separation of two receivers increases. In this paper a new concept of the DGPS operation is introduced. The main objective is to increase the DGPS accuracy and operational coverage with multiple ground reference stations. Each ground reference station broadcasts the locally measured pseudo-range errors and the participating receivers then use the measured errors to compute the best estimate of pseudo-range errors for selected satellites. An algorithm based on the Kalman filtering technique has been developed to optimally process the measurements from all ground reference stations. The Kalman filter statistically weights each measurement according to the distance between the ground reference station and the user. The filter estimates are then used by the receiver for the pseudo-range compensation. Illustrative examples are presented to demonstrate the estimation process of this DGPS implementation with multiple ground reference stations. The general guidelines of its applications as well as some restrictions are also discussed in the paper.
Published in:	Proceedings of the 2nd International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GPS 1989) September 27 - 29, 1989 The Broadmoor Hotel Colorado Spring, CO
Pages:	319 - 323
Cite this article:	Tang, Wang, Johnson, Newton, Graff, Jack, "Differential GPS Operation With Multiple Ground Reference Stations," Proceedings of the 2nd International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GPS 1989), Colorado Spring, CO, September 1989, pp. 319-323.
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