Research And Implementation Of BeidouB2a Signal Tracking Algorithm

In recent years,China’s Beidou navigation system has developed rapidly.The Beidou-3 navigation satellite system was successfully networked in 2022.In the Beidou-3satellite navigation system,the upgraded B2a signal has replaced the original B2I signal,which means that the tracking loop needs to reconsider the tracking algorithm,and the research on the new signal is particularly important.This topic studies the theory and implementation of B2a signal tracking of Beidou 3.The main work contents are as follows:1)Firstly,on the basis of studying the carrier,pseudo code and message in the traditional satellite navigation signal,the composition of B2a signal is deeply studied.The characteristics of the new system signal and the principle of spread spectrum in signal generation are analyzed.Then I learned the working principle and operation mechanism of each module of the navigation system.2)The carrier tracking loop is designed for B2a signals.Different frequency discrimination algorithms and different phase discrimination algorithms are compared.By analyzing the working characteristics of frequency locked loop and phase locked loop,the loop structure of frequency locked loop auxiliary phase locked loop is determined.The principle of loop filter is studied,the performance of different order filters is analyzed,and the carrier tracking loop structure of third order frequency locked loop assisted fourth order phase locked loop is designed to adapt to high dynamic environment.By comparing three carrier tracking loop algorithms,the two-component joint carrier tracking loop that can fully use signal power is selected as the carrier tracking loop in this paper.3)The pseudo code tracking loop based on dual component joint tracking is designed,and the structure and principle of the dual component joint tracking loop of pseudo code are introduced.Analyzing the impact of different phase discriminator of the algorithm on the code tracking loop,and choose the appropriate phase discriminator of the pseudo-code tracking loop.Analyzing the effects of the spacing of correlators on the pseudo-code tracking loop.According to the relationship between the pseudo distance and the pseudo-code phase,the working characteristics of the delay locking loop are studied,and the structure of the pseudo-code tracking loop is determined.4)Use MATLAB simulation to design the double signal combined tracking loop of the design to verify the feasibility of the tracking ring.Based on modular programming ideas,the entire ring is divided into signal processing module,information processing module,locking indication module,loop filter module and local pseudo-code generation module.In terms of implementation,this paper uses ZYNQ development platform to complete.The ZYNQ development board uses an ARM+FPGA design architecture.Complete the information processing part that requires complex calculations on ARM.The signal processing part requiring high-speed signal acquisition is completed on FPGA.After all the designs are completed,simulation tests are carried out on each module respectively.Finally,the antenna is used to receive satellite signals for board level verification.