Research On The Algorithm For GNSS Secondary Code Acquisition And Unambiguous Code Tracking For BOC Signals

With the development of GNSS Modernization, GNSS signal structure hasintroduced some significant changes, such as, new carrier frequencies, new modulationschemes (BOC and its derivative schemes), channel coding, secondary codes and pilotchannels and so on. New GNSS signal structure greatly enhances system performance andbrings challenges for the receivers at the same time. Signal processing technique for thenew GNSS signal structure has become a main focus recently. This thesis focuses onsecondary code acquisition and the unambiguous tracking of BOC signals.Bit sign transition causes a spectrum splitting effect of the CAF (similar to the onegenerated by a BOC), which results in a degradation of acquisition performance evensome errors. Existing secondary code acquisition methods can hardly seek a compromisebetween acquisition performance and computational load. This thesis proposed a newDBZP based secondary code acquisition algorithm which is a combination of DBZP andproper secondary code searching strategy. Compared with existing representativealgorithms, the new algorithm greatly reduces computational load without a noticeabledegradation of acquisition performance. Simulation results verify the validity andperformance of the new algorithm. Finally, potential scenarios are pointed out.The multi-peaked autocorrelation characteristic of BOC modulation may arouse falselock problems of code tracking. This thesis analyses the mechanism of false locks, thenintroduces three unambiguous code tracking algorithms with details: Bump-Jump,ASPeCT and Dual Estimator Technique. Tracking performance is comparatively analyzedin three aspects: tracking jitter, multi-path performance and hardware resource utilizationwith different parameter settings. Comprehensive analysis shows that the Dual EstimatorTechnique is the most promising BOC tracking algorithm currently.