The L2C Signal Tracking Algorithm And Implementation Of GPS Navigation Systems

Global Positioning System (GPS) has been always undergoing changes and upgrade, which willmeet the growing requirement of civilian users, for high-precision positioning in the complexenvironment. U.S government announced a new GPS modernization initiative, one of which isdenoted as L2C signal. Because of using FEC (Forward Error Correction) and TDM (Time DivisionMultiplex), L2C lowers the data demodulation and carrier tracking threshold.As a result, L2C islikely to become the choice for application to personal navigation in wooded areas and insidebuildings. Besides, L2C will provide civilian users the ability to correct the ionospheric delays bymaking dual-frequency measurements, thereby significantly increases accuracy. Currently, L2C istransmitted by eight modernized GPS IIR-M satellites. It’s expected that it will be fully available infuture years. This paper deeply investigates L2C acquisition methods and tracking algorithms.This paper studies the L2C signal tracking algorithms and software defined receiver for L2C toachieve a real-time processing. According to the characteristics of L2C signal, we researched CMcode tracking, CL code tracking and fusion tracking three algorithms. Besides, we compared thethree algorithms by tracking error variance. By comparing the results we summarized a betterperformance tracking algorithm. Simulation results show that data/pilot combined trackingalgorithm has the best performance among the three algorithms both in carrier tracking and codetracking under the same tracking condition. Tracking algorithm using only CL code has bettertracking performance than the one using CM code.