An ANOVA-based GPS multipath detection algorithm using multi-channel software receivers

We present a statistical detection test for GPS multipath based on the one-way ANOVA method. Given an antenna array with a GPS software receiver in tracking mode, the signal from each channel is correlated with a reference signal in blocks of one CA code period. When the relative phase delay for the direct GPS signal is stripped off from each channel, the expected values of the correlates is the same for all of the channels only if no multipath is present. A one-way ANOVA test can then used to detect the presence of multipath. An analysis of this method is presented which shows that the parameters affecting its detection performance can be grouped into three classes: the array size, the signal AOAs, and the processed multipath SNR. Receiver operating characteristic curves are given as a function of the processed multipath SNR for fixed array sizes. They show that good detection performance can be achieved under most operating conditions with less than 10 CA code periods of data. It is also shown that the detection performance of this method improves as the multipath time delay decreases. This suggests that the method could be a useful tool in aiding multipath mitigation techniques whose ability to detect multipath typically degrades as the multipath time delay decreases.