Research On Acquisition Technology For Galileo Satellite Navigation Receiver

With the rapid development of satellite navigation technology in many countries,the satellite signals of many systems are concentrated in a fixed frequency band,resulting in increasingly serious interference between different signals,and the security of the signal cannot be guaranteed.Considering the importance of satellite navigation systems in economic development and national defense construction,new modulation method emerged.In order to solve these problems as soon as possible,now most of the satellite navigation system signals,such as the GPS M-code signals,the GALILEO system El,E5,E6-band signals,"BeiDou ?" B1C satellite signals,have begun to use BOC(Binary Offset Carrier),the new modulated signal,to replace the BPSK modulated signal in traditional satellite signals.Because the BOC modulated signal has the advantages of sharper autocorrelation peaks,splitting spectrum,higher code tracking accuracy and stronger anti-multipath interference capabilities.Therefore,the research on synchronous capture technology for BOC modulated signals is also intensifying in various countries.First,deeply research was conducted on the modulation principle and signal structure of the BOC modulation signal.Based on this general BOC signal,the modulation principle and characteristics of the MBOC modulation signal in the E1 frequency point of the Galileo system are also studied.And the MATLAB was used for related simulation research.A frequency conversion module based on the MAX2769 was designed for its spectrum characteristics.Secondly,lucubrate some of the BOC modulation signal capture algorithms proposed today.Based on a thorough analysis of the mechanism characteristics of the modulated signal in the El band of the Galileo system,a strategy for acquiring MBOC modulated signals using the combination of the secondary sampling method,FFT and accurate acquisition method is proposed.The simulation of the improved algorithm by MATLAB,verifies the correctness of the design.Finally,a Galileo satellite navigation receiver hardware platform based on FPGA+DSP architecture was designed.The improved capture algorithm was written in FPGA using Verilog HDL language,the DSP assists the FPGA in acquisition control,judgment,subsequent signal tracking and navigation message resolution.After finishing joint debugging RF module and improved algorithm on FPGA and DSP,SPIRENT analog sources provide different intensities Galileo E1 signals for testing.The test results show that the improved algorithm can successfully acquire the CBOC(6,1,1/11)modulated signal and achieve the desired goal.Confirmed the correctness of the design,it laid a solid foundation for the tracking of BOC modulation signals and the calculation of navigation messages.