Research Of Carrier Tracking Algorithm Based On UKF For High Dynamic GNSS Software Receiver

High dynamic signal tracking is one of the most important technologies of the GNSS receiver, and carrier signal tracking is the most difficult of the baseband signal disposal. The GNSS signals which are received by software receiver assembled in the high dynamic vector have high Doppler frequency, frequency rate and second derivative of frequency. Therefore, GNSS software receiver applied for high dynamic environment needs high dynamic carrier tracking algorithm accordingly. So in this paper, to solve the problems of high dynamic carrier tracking for high dynamic GNSS software receiver, taking GPS software receiver as an example, a high dynamic carrier signal tracking technology based on Kalman Filter is studied in detail, in order to make GNSS carrier tracking loop can be used in high dynamic conditions, with high precision and stability, and overcome the limit of loop-band.This thesis first introduced the structure of GPS signal and the architecture and principles of GPS software receiver, and the traditional method of tracking GPS signal. Next related knowledge and the characters of different sorts of Kalman Filter are elicited and analyzed in theory, to select which sort is fit for high dynamic carrier signal tracking. Then,the traditional disposal of the baseband signal used by the GNSS receiver is introduced, the limit of which is also shown to prove that such receiver cann't not work steady in high dynamic conditions. Bringing the EKF and UKF into the improved carrier tracking loop, the performance of which are compared and analyzed in theory. Finally, according to the definition of high dynamic, the EKF and UKF algorithm model of high dynamic GPS receiver are designed for carrier tracking. By simulating, the results of the simulation showed: in high dynamic environment, both algorithm can track carrier of GPS signals successfully. However, from the aspect of performance, it can be compared to see: UKF has the less mean square error than EKF. When in the same situation of tracking the carrier signal, UKF has the lowest probability of missing lock.