Research And Implementation Of Blind Acquisition Of Beidou Satelite Signal

GNSS(Global Navigation Satellite System)mainly refers to the GPS navigation of America,GLONASS of Russia,GALILEO of the European Union,and Beidou navigation system of China.GPS navigation system occupies more than 90% market share in the fields of military,commerce and life.In order to break its monopoly position,China must develop its own navigation system.Generally,Beidou satellite navigation and positioning need to go through three stages of signal processing modules: signal acquisition,signal tracking and locking,and signal calculation.Among them,the capture of satellite signal is the first and very important step,because the performance of acquisition algorithm directly influences the accuracy and speed of navigation and positioning.Therefore,it has important practical meaning to study how to capture satellite signals quickly and accurately,which is the research goal of this paper.In essence,Beidou satellite acquisition is to roughly estimate the carrier Doppler frequency and code phase of the satellite signal,but the common acquisition algorithms,such as Serial capture algorithm and FFT-based parallel capture algorithm,have shortcomings of low acquisition speed and low accuracy,which can not meet the requirements of high-precision and fast navigation and positioning in reality.In this paper,an algorithm of Beidou satellite signal acquisition based on blind separation model is introduced.The Doppler frequency and code phase can be accurately solved by the blind separation model of satellite signal,to realize the rapid acquisition of satellite signal.The following are the main research ideas of this paper:(1)Firstly,we study the structure of Beidou satellite signal,and Beidou satellite signal source is built on MATLAB platform as the digital IF signal in the simulation.Through the simulation of pseudorandom code,we can see that the pseudorandom code has good autocorrelation and cross-correlation,which lays the foundation for the next proposed Beidou satellite signal model based on blind separation method.(2)Secondly,because the source signal and transmission channel of Beidou satellite are unknown,the blind signal separation model of Beidou satellite is established by using the theory of blind signal separation.Before blind separation of the mixed signals of Beidou satellite,the preprocessing should be carried out,to enhance the performance of blind signal separation algorithm,which provides a theoretical foundation for the next step to propose a fast and highly accurate Beidou satellite signal acquisition algorithm.(3)Finally,based on the traditional capture methods of satellite signal,an improved highprecision fast acquisition algorithm of Beidou satellite signal is put forward.The proposed algorithm is used to estimate the number of signals,Doppler frequency and code phase of Beidou satellite,and recover the unobservable source signals.In addition,the indicators of false alarm rate,detection probability and common decision strategies are used to evaluate the reliability of the proposed acquisition algorithm.This paper proposes a new acquisition algorithm theory,i.e.a high-precision and fast acquisition algorithm of Beidou satellite signal based on blind separation,and verifies the feasibility and effectiveness of the algorithm through MATLAB simulation platform.Compared with the traditional acquisition method,the simulation results indicate that,the new acquisition algorithm proposed in this paper can achieve high precision and fast acquisition of Beidou satellite signal,and overcome the technical shortcomings of the current acquisition methods that can not accurately and quickly acquire satellite signals simultaneously.The algorithm can more effectively meet the actual needs of Beidou satellite acquisition,which has good academic research value and engineering application prospect.