Multiple GPS receiver multipath mitigation technique

The applications using differential GPS (DGPS) have grown in recent years, and the dominant error source for many DGPS techniques is reference receiver multipath. As a result, there is great interest in reducing reference receiver multipath, especially for safety-critical applications such as DGPS-based precision landing. 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. Using this method, a least-squares condition adjustment is performed to generate a multipath estimate for each individual receiver/satellite pair. It does so on an epoch by epoch basis, so no filtering over time is required, and no initialisation period is necessary. Static and dynamic test results using this method are presented. For these tests, 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 enhance carrier-phase integer ambiguity resolution.