A Kalman Filter Based Tracking Loop in Weak GPS Signal Processing

The GPS software receiver´s architecture is reviewed. And a classic second order phase lock loop and the loop parameters´ configuration are described. Though analyzing the total phase jitter, it is shown that under a realistic weak signal condition, the tracking loop´s ability is inhibited by the noise and transient frequency jump. Then an optimal estimation based intelligent integrated tracking loop is presented. A Kalman filter based optimal estimation algorithm is proposed, it effectively depresses the effective of frequency jump by correctly estimating the frequency of local carrier on the next time nod. At last some testing experiments is done, the results verified that the proposed study have a remarkable performance in processing low C/N carrier signal.