Design And Hardware Implementation Of Dual Channel Fast Acquisition Platform For BDS-3 B1C Signal Receiver

In June 2020,the third generation Beidou satellite network has been completed,and the BDS has realized the navigation capability from regional to global coverage.The mature GNSS system needs not only the construction of the space terminal,but also the support of the ground terminal and the user terminal.In order to realize the BDS to provide continuous,real-time,accurate location,speed and time services for the ground terminal,the research and development of baseband chip and receiver is very important.As the primary part of the receiver baseband digital signal processing,the acquisition module directly affects the accuracy,reliability and integrity of the follow-up tracking and positioning.This paper mainly studies the B1C signal adopted by the BDS-3 and the design and implementation of its navigation receiver acquisition module,Firstly,the modulation mode of B1C signal is modeled and analyzed,and the characteristics of B1C signal are summarized.Then,the acquisition algorithms of traditional GNSS signals and BOC signals are studied,and the core ideas and research directions of various algorithms are analyzed.Based on the above analysis,the main work of this paper is as follows:(1)In view of the characteristics that B1C signal adopts dual channel modulation of data and pilot,and the ambiguity caused by autocorrelation sub peak of BOC Signal,a dual channel B1C signal incoherent acquisition algorithm design combined with sub peak elimination technology is proposed.It is verified on MATLAB platform that the algorithm is superior to the single channel acquisition algorithm,can eliminate the influence of sub peak,and runs correctly on software receiver.(2)After the MATLAB platform is verified,the algorithm is transplanted to the FPGA hardware platform,and a fast acquisition algorithm based on FFT average correlation is proposed according to the characteristics of the hardware platform.Finally,according to the simulation and debugging of Modelsim,it is verified that the design can complete the acquisition of B1C frequency point signal,and the processing time of FFT is shortened by about 20%,which reduces the dependence of system time on hardware processing process and improves the real-time processing ability of engineering implementation.