Reduction of Pseudorange Multipath Error in Static

Nobuaki Kubo and Akio Yasuda

Abstract:	The accuracy requirements of the different positioning applications vary widely. Many important applications, however, require greater accuracy under multipath conditions. DGPS can provide meter-level and, even sub-meter-level, position estimates depending upon the closeness of a user to a reference station. Multipath and receiver noise are uncorrelated at the reference and user receivers, and cannot be corrected by DGPS. Therefore, it is important to minimize these errors by careful siting and equipment selection at both reference and user stations. Several researchers have devised methods experimentally and theoretically to counter multipath effects in GPS positioning. A few special correlator techniques also have been developed. However applying code multipath estimated from GPS measurements to pseudorange in GPS positioning is not implemented often. This paper shows an improvement of accuracy in static DGPS positioning in case of applying code multipath we estimated to pseudorange. This paper also shows the effect of diffraction in pseudorange. In order to estimate and remove code multipath, not only code minus carrier technique but also geometrical relation between GPS antenna and reflectors are used. Geometrical relation is very useful to estimate some multipath parameters. Multipath parameters are the amplitude, the delay and the phase of the reflected signal relative to the direct signal. Once multipath parameters are known, the effect of code multipath relative to pseudorange can be estimated. This method was tested under multipath conditions. As a result, vertical and horizontal errors are decreased significantly by using this method and carrier smoothing. It is also confirmed that pseudorange wasn’t almost affected due to diffraction, though carrier to noise ratio (C/N0) measurements decrease radically due to diffraction.
Published in:	Proceedings of the 15th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GPS 2002) September 24 - 27, 2002 Oregon Convention Center Portland, OR
Pages:	452 - 459
Cite this article:	Kubo, Nobuaki, Yasuda, Akio, "Reduction of Pseudorange Multipath Error in Static," Proceedings of the 15th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GPS 2002), Portland, OR, September 2002, pp. 452-459.
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