Performance Evaluation of the Multipath Estimating Delay Lock Loop

Bryan Townsend, D.J. Richard van Nee, Patrick Fenton and Keith Van Dierendonck

Abstract:	In many differential GPS applications, the positioning errors are mainly caused by multipath propagation. While the C/A-code noise errors are in the order of a decimetre when using Narrow CorrelatorTM spacing, the errors caused by multipath can be at the metre level. In a previous paper, the authors demonstrated that it is possible to greatly reduce multipath errors by using a new receiver concept, the Multipath Estimating Delay Lock Loop (MEDLL). The MEDLL estimates both line-of- sight and multipath parameters, thereby reducing the influence of the multipath signals on the code and carrier estimates of the line-of-sight signal. The basic one-channel MEDLL prototype receiver has been expanded to a multi-channel receiver, which makes it possible to evaluate the performance improvement of pseudorange observables by using double differencing or other techniques that isolate multipath errors. Measurements are performed in various environments in order to compare the MEDLL code and carrier performance as compared to a standard receiver using Narrow Correlatorm spacing. The improved performance of the MEDLL can be of great help in critical DGPS applications, where the multipath errors associated with using conventional receivers can easily exceed the accuracy requirements.
Published in:	Proceedings of the 1995 National Technical Meeting of The Institute of Navigation January 18 - 20, 1995 Disneyland Hotel Anaheim, CA
Pages:	277 - 283
Cite this article:	Updated citation: Published in NAVIGATION: Journal of the Institute of Navigation
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