Analysis of Simulated Performance of Integrated Vector Tracking and Navigation Loops for GPS

Abstract

An alternative GPS signal tracking method that uses an extended Kalman-Bucy filter in place of traditional independent, parallel tracking loops is presented in this thesis. Furthermore, this method is extended into a combined tracking and navigation filter coupled with inertial sensors. This approach significantly reduces filter design complexity and allows for optimal navigation performance in a variety of conditions. Specifically, the proposed method is demonstrated under high dynamic platform motion while experiencing significant levels of jamming. A simulation in a single-axis configuration was used to compare the proposed method to an existing, aided fixed-gain method in order to ascertain the expected level of anti-jam performance as well as immunity to dynamic stress. Results from this simulation indicate a nominal, expected positioning performance improvement of 5 meters with improvements of up to 25 meters in some cases. Additionally, increased jamming immunity of 17 dB J/S was seen in the simulations. A simulation comparing IMU's of differing grades was also run to ascertain the proposed method's dependence upon inertial sensor quality.