Mitigation of GPS Multipath via Exploitation of Signal Dynamics

Joseph M. Kelly, Michael S. Braasch

Abstract:	In the implementation of differential GPS, correlated errors are subtracted out such that the dominant remaining error source is multipath. The dynamic nature of the GPS constellation coupled with a typically time-varying line of sight distance causes all multipath reflections to have some inherent fading frequency. Previous theoretical work [1] has shown that multipath error can be reduced significantly if its fading frequency is greater than the code tracking loop bandwidth. The purpose of this paper is to show that a coherent delay lock loop (CDLL) will offer the advantage of an unbiased code phase estimation over the more robust non-coherent loop (NCDLL) for fast-fading multipath. The remaining slow-fading reflection can often be mitigated by proper antenna design and siting. The result will be a reduction in multipath error that stems from implementation of the, as yet, unexploited CDLL. What follows is significantly improved accuracy in DGPS applications. Simulation data are presented and discussed to verify the theoretical performance predictions.
Published in:	Proceedings of the 55th Annual Meeting of The Institute of Navigation (1999) June 27 - 30, 1999 Royal Sonesta Hotel Cambridge, MA
Pages:	619 - 624
Cite this article:	Kelly, Joseph M., Braasch, Michael S., "Mitigation of GPS Multipath via Exploitation of Signal Dynamics," Proceedings of the 55th Annual Meeting of The Institute of Navigation (1999), Cambridge, MA, June 1999, pp. 619-624.
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