De-noising method for tracking results of GPS software receiver based on wavelet packet soft-threshold algorithm

An algorithm using three-layer wavelet packet to de-noise threshold is proposed for processing the output of tracking module in software GPS receiver.The decomposition coefficient of each node is obtained from the decomposition of third-layer wavelet packet.The Shannon entropy criterion is given,and the best wavelet packet is selected.Then a soft-threshold algorithm is used to quantify the decomposition coefficients of each node and reconstruct these quantified coefficients to obtain the de-noised signals.Simulations are made to compare with conventional IIR filter,and the results show that the SNR and RMS are improved 4 dB and 0.14 respectively by the proposed method,and the de-noised signals are much smoother.These are beneficial to the bit synchronization of the receiver.