GPS Multipath Detection with ANOVA for Adaptive Arrays

We present a statistical detection test for GPS multipath based on a one-way ANOVA method. Given an antenna array with a multi-channel software GPS receiver in tracking mode, the signal from each channel is correlated with a reference signal in batches of one CA code period. The relative phase delay for the direct line-of-sight (DLOS) GPS signal from each antenna is then removed. Assuming the multipath and DLOS signal have different angles of arrival (AOA), the average correlator outputs are identical for all channels if no multipath is present. The ANOVA test is applied to detect the presence of multipath. Receiver operating characteristic (ROC) curves under various signal conditions are presented to assess the performance of the ANOVA method. Theoretical analysis and simulation results show that good detection performance can be achieved under most operating conditions using less than 10 CA code periods of data. The detection performance improves as the multipath delay time decreases.