Self-Differential GPS-What Are the Limits?

E.M. Somerville and J.F. Raquet

Abstract:	This paper describes a self-differential GPS (SDGPS) technique in which position is calculated relative to a previous time, rather than relative to a reference receiver, using only carrier-phase measurements. This approach results in a relative position measurement, which can be useful for some applications. The approach presented can be accomplished in real-time using a single receiver (i.e., no reference receiver is needed), and no ambiguity resolution is necessary. This paper describes the algorithm and then evaluates performance using real data under a variety of conditions, including moving/stationary, use of ionospheric-free measurements, use of precise orbits and clocks, and use of a tropospheric model. The results show that relative position can be calculated to sub-meter accuracy over a three hour time period, as long as all possible error mitigation techniques are applied (including use of precise orbits and clocks and ionospheric-free measurements). The error quality degrades as error mitigation techniques are removed. The most significant error source was tropospheric error (with no model applied), followed by ionospheric error and precise satellite position and clock. Additionally, motion did not seem to have a significant effect on the results.
Published in:	Proceedings of the 2006 National Technical Meeting of The Institute of Navigation January 18 - 20, 2006 Hyatt Regency Hotel Monterey, CA
Pages:	847 - 857
Cite this article:	Somerville, E.M., Raquet, J.F., "Self-Differential GPS-What Are the Limits?," Proceedings of the 2006 National Technical Meeting of The Institute of Navigation, Monterey, CA, January 2006, pp. 847-857.
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