Research On B1C Signal Acquisition Technology Of BDS-3

During the rapid development of satellite navigation technology,many satellite signals are located in one frequency band,which causes interference among signals to become more and more serious.Since satellite navigation technology occupies an important position in national strategic planning,a new modulation technology was born.In order to improve the problem of spectrum congestion and interference among signals,the M code in the US satellite navigation system(GPS)and the E1 frequency signal in the European Union's satellite navigation system(GALILEO)have begun to adopt BOC(Binary Offset Carrier modulation technology).Since the autocorrelation peak of the BOC modulation signal is sharper than the correlation peak of the BPSK modulation signal and the BOC modulation technique can shift the spectrum,and the BOC modulation signal has high tracking accuracy and strong anti-multipath capability.Many countries have begun research on BOC modulated signal acquisition algorithms.This topic studies the structure of BOC modulated signals on a satellite navigation receiver based on FPGA+DSP.Among them,the BOC(1,1)modulated signal and the QMBOC(6,1,4/33)modulated signal of the B1C frequency point of BDS-3 are mainly studied.According to the MATLAB simulation results of the spectral characteristics of the B1C signal,the down-conversion module of the receiver is designed in the MAX2769 integrated chip.Then,the existing acquisition algorithms of BOC modulation signals are studied.Based on the thorough analysis of the mechanism characteristics of BOC modulation signals in the B1C frequency band of BDS-3.The acquisition of the BOC modulated signal is achieved by a sub-sampling with subcarrier phase cancellation as an improved direction of subsampling combined with a parallel code phase.In the MATLAB simulation software,the feasibility simulation of the algorithm is carried out.The simulation results show that the method is feasible.Finally,B1C signal acquisition is implemented in the FPGA,and the DSP in the receiver performs control and decision during the acquire process.After the joint debugging of the RF module and the acquisition algorithm are completed in the receiver,the SPIRENT satellite signal recorder is used for the acquire test.The test results show that the algorithm can acquire the BOC(1,1)modulated signal in the B1C frequency point and lay the foundation for the tracking,frame synchronization and PVT(Position,Velocity,Time)solution of the B1C signal of BDS-3.