Research On Acquisition And Tracking Method Of Beidou-3 Multi-band Satellite Signal

Now BeiDou Navigation Satellite System(BDS),as one of the Global Satellite Navigation Systems(GNSS),is steadily promoting construction in accordance with the development strategy.In order to achieve global coverage and better service to the needs of users in China and around the world,BDS-3 is been developing and establishing now.With the acceleration of the construction of BDS-3,its demand and application market will also rapidly expand and develop.Therefore,as the basis for incorporating BDS-3 into user applications,the acquisition and tracking of B1 C,B2a and B3 I signals with better performance in BDS-3 has become a crucial research content.Since Beidou-3 satellites have just been put into use and new signals have been added,there is little research on the acquisition and tracking methods of these new signals.In this thesis,the signal structure was analyzed and improved acquisition and tracking methods were proposed.In addition,the study can also provide a theoretical basis for the use of BDS-3.The research in this thesis mainly includes the following five aspects:1.The modulation mode and basic signal characteristics of Beidou-3 signals were analyzed.Meanwhile the Binary Offset Carrier(BOC)used in B1 C signal and the Binary Phase Shift Keying(BPSK)used in B2 a and B3 I signals were compared.In addition,the autocorrelation properties for both modulation methods were studied.2.The method of generating the ranging code of each satellite signal of BDS-3 was analyzed which includes the method of truncation of Weil code and truncation of Gold code,and the local replica of each signal ranging code was completed.Simultaneously their autocorrelation and cross-correlation properties were studied which verified their good performance.3.The real signals of each frequency band of BDS-3 were gathered by the receiver.The problem of Doppler frequency shift encountered during satellite signal acquisition was also introduced.Meanwhile the time domain sequential search method and FFT search method that commonly used in the field of signal acquisition were analyzed.In addition,an improved FFT search method was proposed to complete the acqusition of the Beidou-3 signal.4.Based on the acquisition,the tracking method was researched in order to track various signals which including the working principle of carrier tracking loop and code tracking loop.An adaptive phase-frequency switching carrier tracking loop was designed for the characteristics of the Beidou-3 signal.The signal tracking was completed and the results can verify the correctness of the tracking method.At the same time,the method of calculating the carrier-to-noise ratio was designed which is helpful for judging the satellite signal strength.5.The navigation message structure,teletext decoding method and satellite position algorithm of Beidou-3 B1 C signal were analyzed.The correctness of the decoding method was verified by calculating the satellite orbit height.