Innovative Adaptive Algorithms for Multipath Mitigation and Interference Suppression for GPS Receivers

The satellite-based GPS systems are vulnerable to intentional and unintentional interferences. Much work has been done on the development of anti-jam techniques using adaptive arrays for GPS receivers. Almost all of the anti-jam techniques proposed are based on the standard Capon beamformer or its robust variations. To improve the interference suppression performance of broadband jammers and to increase the number of narrowband jammers that can be suppressed, STAP and the related SFAP techniques have been used with beam forming/null steering. Multipath mitigation is another important challenge for GPS receivers. If the multipath time delays are small, the direct and the reflected paths are highly correlated and the multipath can affect the accuracy of the GPS receiver significantly. However, none of the aforementioned adaptive array techniques can work well when the desired signal is highly correlated with its multipath signals. The main objective of this program is to develop innovative techniques for the effective mitigation of multipath effects on airborne anti-jam GPS adaptive antennas. The secondary objective is to develop, test and deliver a software-based simulation capability that realistically simulates a GPS receiver equipped with a small anti-jam GPS antenna array operating in a multipath and interference environment.