Abstract:

To meet the high dynamic environment, global navigation satellite system receivers often combine frequencylocked loop with phaselocked loop to track carrier. An improvement on cross product automatic frequency control loop, which is commonly used, is proposed. The new loop adopts the switch between two identification methods. As a result, it can overcome the data ambiguity and expand the frequency discrimination range 4 times while maintaining the same tracking accuracy. The main factors affecting the tracking accuracy include noise tracking error and dynamic stress error. It is found that there is a greater gap between the traditional theory of thermal noise error and actual results. Using loop linear approximation and considering the relevance of noises in identification results, the new thermal noise tracking error equation is derived. The new value is less than one-fifth of traditional theoretical analysis. Finally, the analysis of frequency discrimination range and thermal noise tracking error is proved by simulation results.