Precise GPS Signal Tracking in Interference and Multipath Environment Using a Multi-Channel Software Receiver

The objective of the project is to develop techniques to allow precise tracking of GPS signals in the presence of multipath interference. Our work has focused specifically on a difficult class of multipath whose time delay relative to that of the direct line of sight signals DLOS is very short. This form of multipath is difficult to detect and mitigate using traditional correlator-based methods. Our approach overcomes the limitations of the existing methods by exploiting the spatial diversities between the DLOS and multipath sources. This approach requires the use of a receiver array and batch-based software receiver processing. The spatial diversity between the multipath and DLOS GPS signals makes it possible to estimate the angle of arrival AOA for each signal. Knowledge of the source AOAs makes it possible to reconstruct the pseudo-inverse for the array manifold and to recover DLOS and multipath signals. During the three year funding time period, we successfully developed and implemented algorithms for detection, estimation, and mitigation of the short delay time multipath signals. In this report, we will give an overview of the technique, the detection, estimation, and mitigation algorithms, and performance evaluations of the method.