Multipath Effects on GPS Code Phase Measurements

Richard D.J. van Nee

Abstract:	Little is known about the influence of multipath propagation on code phase measurements. It is generally assumed that multipath-induced range errors can be reduced by long averaging times, which is not valid, however, for two reasons. First, a mean range error exists due to the nonlinearity in the phase estimation. Second, for stationary users the periodicity of the range error caused by multipath can reach values in the order of one hour, which, in most applications, makes it practically impossible to minimize the error by averaging. This paper presents an analysis of the multipath-induced range errors, assuming the code phase is measured with the widely used noncoherent delay lock loop. Both specular and diffuse reflections are considered. A rough estimate for the fading bandwidth is given for mobile and stationary users, showing that averaging is far more effective for mobile than for stationary users. In general, however, a certain mean range error is present for both stationary and mobile users, depending on the power-delay profile of the received signal.
Published in:	Proceedings of the 4th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GPS 1991) September 11 - 13, 1991 Albuquerque, NM
Pages:	915 - 924
Cite this article:	Updated citation: Published in NAVIGATION: Journal of the Institute of Navigation
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