Estimation of Multipath Error in GPS Pseudorange Measurements

Abstract

Multipath is a significant source of error when using GPS, and one that is not eliminated using differential GPS (DGPS). Rather, it becomes the major remaining source of error. This paper presents a new algorithm that can estimate multipath errors in real time for a stationary, single-frequency receiver in the case of one dominating, specularly reflected multipath signal. This algorithm exploits an observed strong correlation between the signal-to-noise ratio (SNR) measurements and multipath errors. Measurements from this new method are compared with those from a second method using a dual-frequency receiver. The paper also includes a test of the algorithm's performance using DGPS. The results show that the estimation method has the potential to reduce both the standard deviation of errors and maximum errors in DGPS positioning by 40 to 50 percent.