Improvements In Dynamic GPS Positions Using Track Averaging

James R. Clynch, Richard Franke and Beny Neta

Abstract:	The issue of improving a Global Positioning System (GPS), Precise Positioning System (PPS) solution under dynamic conditions through averaging is investigated. Static and dynamic data from the Precision Lightweight GPS Receiver (PLGR) were used to analyze the error characteristics and design an averaging technique for dynamic conditions. It was found that the errors in PPS solutions are dominated by the satellite broadcast ephemeris parameters. The solution errors are highly correlated for a given set of satellites/ephemeris. The variation can be as low as 0.4 m in dynamic conditions, but a slowly changing "bias" of several meters is also present. For fitting the location of a road observed repeatedly with a PPS receiver a technique based on "space curves" was developed. Here the solutions are transformed from functions of time to functions of space (location). These then are used. Curves could be fit with a Bézier polynomial easily to the 0.4 m level. These analytic curves were then used to form an ensemble average. The bias vectors between the solutions were found with least squares estimation. These vectors were averaged using several techniques. This idea was applied to a short road segment. Using 9 independent measurements taken over 6 months, the road was surveyed at the submeter level.
Published in:	Proceedings of the 2000 National Technical Meeting of The Institute of Navigation January 26 - 28, 2000 Pacific Hotel Disneyland Anaheim, CA
Pages:	768 - 778
Cite this article:	Clynch, James R., Franke, Richard, Neta, Beny, "Improvements In Dynamic GPS Positions Using Track Averaging," Proceedings of the 2000 National Technical Meeting of The Institute of Navigation, Anaheim, CA, January 2000, pp. 768-778.
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