GPS Dynamic Multipath Analysis in Urban Areas

Bernd Eissfeller, Jon Olafur Winkel

Abstract:	Urban areas cause a very severe multipath environment for absolute and differential GPS positioning. In order to analyze the impact of multipath in urban canyons on pseudorange and carrier phase measurements a detailed and rigorous multipath model was developed, taking into account the transmission path including depolarization and damping effects and the receiver code and phase tracking functions. A large number of reflectors (buildings) and multiple reflections can be included in the model in order to estimate the impact on GPS positioning in a very realistic way. In the paper the mathematical structure of the dynamic multipath model is presented. The destabilzation potential of multipath for the closed tracking loops is discussed. Simulation results are presented and special consideration is given to the multipath effects in specific urban environments. It is shown that many critical tracking conditions in urban environment could occur, where the code and phase detector functions are heavily deformed and multiple zeros of the detector exist It was found that a conventional stationary multipath analysis, i.e. finding the zeros of the code and phase detector function, is not sufficient for all cases of operation, and the dynamic approach is superior to it. This holds especially for the case, where the Doppler difference between direct and multipath signal is approaching the bandwidth of the tracking loops.
Published in:	Proceedings of the 9th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GPS 1996) September 17 - 20, 1996 Kansas City, MO
Pages:	719 - 727
Cite this article:	Eissfeller, Bernd, Winkel, Jon Olafur, "GPS Dynamic Multipath Analysis in Urban Areas," Proceedings of the 9th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GPS 1996), Kansas City, MO, September 1996, pp. 719-727.
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