Research On Gps Multipath Detection And Suppression Method Based On Correlator Output

With the completion of the Beidou satellite navigation system network,Beidou has become the third mature satellite navigation system after the United States GPS and Russian GLONASS.Due to the signal system and electromagnetic wave propagation characteristics,multipath interference still has a serious impact on the signal processing and positioning of the receiver in complex environments such as urban areas,and it has always been a hot and difficult problem in satellite navigation signal processing research.Due to the different scenarios generated by multipath,the signal fading and delay caused by it are very uncertain.It is difficult to use modeling technology or differential technology to eliminate the multipath effect error in the navigation solution link,and the suppression methods are limited;In the front-end baseband signal processing link,the existing narrow correlation technology and high-resolution correlator technology have limited suppression effects on the multipath effect,and some features of the correlator are not fully utilized.Therefore,the research uses the baseband solution link to merge navigation Further research on the solved multipath effect suppression technology is very necessary.Based on the in-depth analysis and research of traditional multipath detection and suppression strategies,the paper focuses on starting from the baseband correlation curve change,exploring effective multipath detection schemes,based on this,classifying the tracked satellite signals whether they are affected by multipath,and then applying iteration The weighted model performs multipath suppression and further improves the quality of navigation solution.The specific research content is as follows:First,analyze the relevant characteristics of the multipath effect,study the mechanism of the multipath effect and the characteristics of modern navigation satellite signals.In-depth analysis of the correlation ambiguity of the BOC signal is carried out,and an improved de-blurring algorithm is proposed to make the autocorrelation function waveform of the BPSK signal similar to that of the BPSK signal,so that the same solution can be used for follow-up The processing of multipath detection and suppression,simulation verifies the effectiveness of the processing scheme.Secondly,study the influence of multipath effect on the output of the tracking link correlator.Take GPS L1 as an example to deeply analyze the multipath detection algorithm for BPSK modulated signal,including carrier-to-noise ratio index,CMCD index,ratio index,Delta index,Double-Delta index,the detection performance of each index is verified by simulation,and the optimal multipath detection scheme combining the carrier-to-noise ratio index,CMCD index,and Delta index is comprehensively considered.In order to further improve the reliability of the detection result,the multipath detection stage is introduced The window filtering process overcomes the problem that external interference has a greater impact on the detection result of a single indicator.The advantages of the design scheme are verified through simulation comparison and data analysis.Then,on the basis of studying traditional multipath suppression algorithms(narrow correlation technology,HRC technology,and improved HRC technology)that improve the discriminator of the tracking link,the appropriate discriminator is determined from the comprehensive analysis of the suppression effect and implementation complexity,and uses The aforementioned research methods form weighted reference information.In the receiver solution process,WPDOP is used as the reference of the measured value.An iterative weighted screening model is designed to determine the optimal weight combination of each measured value.This scheme can avoid the traditional direct elimination of quality.Poor measurement values lead to situations where positioning is impossible,which improves the positioning accuracy of the receiver in complex environments and suppresses multipath effects.Finally,the optimized multipath detection algorithm and the multipath suppression model considering WPDOP are cascaded,and the multipath signal generated by the simulator is used to complete performance testing and functional verification.The test of multipath detection proves that the proposed windowing filtering scheme can achieve 96% and 93%detection probabilities of multipath signals in static and dynamic scenes respectively,and the false alarm probability is 1.53e-3,confirming the detection The effectiveness of the program.Through the analysis of the positioning results of the cascade scheme,it can be seen that the iterative weighting scheme can improve the positioning performance by 19% and 27% in static and dynamic scenarios,respectively,indicating that the overall scheme in this paper is reasonable and effective.