GPS Marine Position Improvement in the Post SA Era

James R. Clynch

Abstract:	An absolute GPS position is a function of the errors in the ranges and the geometry of the satellites. For the Precise Positioning System the errors in the ranges do not look like white noise over periods shorter than a day. These errors are dominated by errors in the Broadcast Orbit and Clock parameters received in real time by the user. The form of these errors will be examined. The observed range errors look much like large (several meters) biases or slowly changing values with a small random component on top of this. Techniques to model these errors and improve the positions are presented. The techniques center on the use of auxiliary information such as altitude, and attitude as well as the use of an atomic clock. Only the total effects on ranges in a local area are modeled. A orbit/clock improvement is not possible with the information at a single site.
Published in:	Proceedings of the 13th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GPS 2000) September 19 - 22, 2000 Salt Palace Convention Center Salt Lake City, UT
Pages:	1421 - 1426
Cite this article:	Clynch, James R., "GPS Marine Position Improvement in the Post SA Era," Proceedings of the 13th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GPS 2000), Salt Lake City, UT, September 2000, pp. 1421-1426.
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