Research On Direction Finding Technology Based On Sparse Reconstruction Algorithm

Space signal DOA estimation is an important research direction in array signal processing technology,and it has important applications in military,industrial and other fields.With the development of radio technology and the increasingly complex electromagnetic environment,the electromagnetic interference in space is becoming more and more severe,which puts higher requirements on the traditional direction finding technology.The direction finding technology based on the sparse reconstruction algorithm adapts to low signal-to-noise ratio,less snapshots,and has the advantage of less calculation,so it has become one of the hot topics in the research of direction finding algorithms.At present,the greedy algorithm in the sparse reconstruction algorithm has higher precision and less computational power in DOA estimation.However,the algorithm still has some deficiencies in stability and accuracy.This paper deeply studies the DOA estimation of the greedy algorithm and optimizes the algorithm's atomic matching process.Another research focus of this paper is DOA estimation of multipath coherent signals.Separate signals and coherent signals are processed by subspace algorithm and sparse reconstruction algorithm,respectively,to achieve DOA estimation of mixed signals.The details are as follows:Firstly,this paper studies the basic principle and signal receiving model of array signal DOA estimation.Further,it studies the principle of sparse reconstruction algorithm and the array signal receiving model based on sparse reconstruction algorithm,which lays the foundation for the following research.Secondly,the research analyzes the advantages and disadvantages of the existing three greedy algorithms.In order to improve the performance of the algorithm,the key steps of the optimization algorithm are optimized.In this paper,the particle swarm optimization algorithm is used to optimize the matching process of atoms,and the backtracking strategy in the compressed orthogonal matching tracking algorithm is used to perform a second inspection on the atoms that have been matched to improve the accuracy of the algorithm.Then,considering the complex direction finding environment in practical applications,the multipath effect will occur during the propagation of the signal.Thesignal received by the array contains both independent and coherent signals,and then the algorithm for processing mixed signal DOA estimation is studied.Through the difference method,the covariance matrix of the signal received by the array is decomposed into three parts: an independent signal matrix,a coherent signal matrix,and a noise matrix.A subspace algorithm is used to process the DOA estimation of independent signals.Construct the coherent signal into a sparse block matrix,construct a perception dictionary,reduce the correlation of the columns in the original sensing matrix,match the atoms through the maximum correlation between the perception dictionary and the residual,and improve the DOA estimation performance of the greedy class algorithm for the coherent signal group.Finally,based on GNU Radio and software radio platform,a basic direction finding system was built.The main modules of the system include a signal generation module,an algorithm processing module,and a result display module.Simulation experiments are carried out in the system to verify that the DOA estimation of the algorithm in this paper has high accuracy.