Wide Area Differential GPS: A Performance Study

Vidal Ashkenazi, Christopher J. Hill, Jim Nagel

Abstract:	Conventional DGPS systems operate on the principle that the two main error sources (ie the satellite ephemeris and the atmospheric delay) are spatially correlated. Pseudorange measurements made at precisely located reference stations are compared to cotresponding ranges computed from the known coordinates, and the errors derived are transmitted as differential corrections for application by DGPS users within range. The drawback of such systems is the limited range over which the differential corrections are valid, due to the rapid decorrelation of the error sources with increasing distance from the reference station to the user. This research and development study, which was commissioned by Inmarsat, has been jointly carried out by Nottingham University and British Aerospace. It has led to the development of a Wide Area DGPS (WADGPS) system, which will generate corrections for users over an entire Inmarsat ocean region. The system is based on a limited number of reference stations which are sufficient to spatially model the ephemeris, atmospheric and SA errors. The resulting corrections have been found to lead to accuracies comparable to those obtained by conventional DGPS, with no dependence on the distance between the user and reference sites.
Published in:	Proceedings of the 5th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GPS 1992) September 16 - 18, 1992 Albuquerque, NM
Pages:	589 - 598
Cite this article:	Updated citation: Published in NAVIGATION: Journal of the Institute of Navigation
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