Multiple Reference GPS Receiver Multipath Mitigation Technique

John F. Raquet

Abstract:	There has been much recent interest in developing methods for reducing code and carrier-phase multipath, as multipath has become the dominant error source in many differential GPS applications. Many of the methods for reducing multipath involve signal processing methods internal to the receiver, which may not be practical for many users. Other methods involve filtering over time to take advantage of the time correlation of multipath errors, or generating a map of the multipath environment surrounding an antenna. A new method for reducing code and carrier phase multipath is presented, which uses measurements from multiple receivers in order to obtain accurate estimates of code or carrier phase multipath. Other error sources such as atmospherics can also be detected. Using this method, a least-squares condition adjustment is performed to generate a multipath estimate for each individual receiver/satellite pair, and it does so on an epoch by epoch basis, so no filtering over time is required, and no initialization period is necessary. The double difference positioning solution generated by using a single reference receiver after the condition adjustment is identical to the solution generated by performing a complete least squares position solution using all available measurements from all of the reference receivers. Initial test results using this method are presented. For this test, code differential positioning is performed with and without the adjustment, and it is shown that the adjustment significantly improves positioning accuracy. It is also demonstrated that the condition adjustment can improve carrier-phase integer ambiguity resolution.
Published in:	Proceedings of the 52nd Annual Meeting of The Institute of Navigation (1996) June 19 - 21, 1996 Royal Sonesta Hotel Cambridge, MA
Pages:	681 - 690
Cite this article:	Raquet, John F., "Multiple Reference GPS Receiver Multipath Mitigation Technique," Proceedings of the 52nd Annual Meeting of The Institute of Navigation (1996), Cambridge, MA, June 1996, pp. 681-690.
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