Research On Array Calibration And Robust Estimation Algorithm For Non-uniform Sparse Array

DOA estimation is one of the research contents of array signal processing,which is widely used in seismic exploration,radar,wireless communication and other fields.Because of its larger aperture,less elements and high estimation performance,nonuniform sparse linear array has attracted widespread attention in academia and industry.This paper mainly studies the array calibration and robust DOA estimation algorithm based on the nonuniform sparse linear array.The research is carried out on the techniques of the mutual coupling modeling,robust estimation method against the mutual coupling effect,amplitude phase error calibration,and the performance analysis of the differential array MUSIC.The main work of this paper is as follows:(1)A robust DOA estimation algorithm for the mutual coupling effect of nested arrays is proposed.Compared with the existing algorithms,the proposed algorithm can estimate more angles and obtain better estimation performance.This algorithm analyzes the relationship between the array structure of the nested array and the mutual coupling effect,points out that the virtual array is affected by the mutual coupling effect,constructs the received signal model of the differential array with the mutual coupling effect reduced,and then uses the joint sparse estimation technology to realize the DOA estimation,so that the number of estimated signals can exceed the number of array elements.(2)A robust DOA estimation method under the angle dependent mutual coupling effect and multipath effect is proposed.Firstly,according to the structure of the mutual coupling matrix,the middle subarray of the received signal is extracted to eliminate the mutual coupling effect,and then the linear prediction model of the front and back terms is constructed and solved to estimate the DOA of the coherent signal,so as to achieve higher degree of freedom and better estimation performance.(3)A method of array calibration for amplitude phase error of nonuniform linear array is proposed.Using a single auxiliary source at unknown direction,firstly,a linear equation system is constructed according to diagonal of covariance matrix,and amplitude error is estimated.Then,the DOA and amplitude phase errors are estimated alternately in the differential co-array and physical array respectively.Finally,the array can be calibrated.(4)Aiming at the Gaussian modeling error of nonuniform linear array,the estimation performance of MUSIC based on differential co-array is analyzed,and two kinds of the MSE expressions are proposed.Firstly,by analyzing the augmented covariance matrix,the deviation expression of music estimation is given.Then,according to the deviation expression,the MSE asymptotic expression of differential co-array MUSIC is obtained.Furthermore,the relationships between MSE asymptotic expression and SNR,MSE and number of sources,MSE and source interval,and MSE and sensor numbers are analyzed.Finally,the validity of the proposed expressions is verified by experiments.