Improving Tracking Performance of PLL Based on Wavelet Packet De-noising Technology

The Phase-Locked Loop is used to track an incoming signal and provide accurate carrier phase measurements on GPS receivers. However, the PLL performance is affected by the thermal noise and dynamic stress. In order to resolve the conflict between reducing PLL noise and overcoming the dynamic stress, some compromises must be taken in PLL design. This paper proposes a wavelet packet de-noising technology to resolve this conflict. The wavelet packet de-noising technique effectively eliminates the effect of the noise and allows broadening the PLL bandwidth. The performance is evaluated by real signals test. The results show that this method outperforms the ordinary method in terms of Signal-to-Noise Ratios (SNR) and Relative Mean-Square Error (RMSE).