Study Of DOA Estimation Algorithm For Distributed Multi-shipboard Swothr Based On Array Interpolation

Distributed Multi-Shipboard Surface Wave Over-The-Horizon Radar is a new kind of SWOTHR, the transmitters and receivers of which are set on various ships in a battle group. It has the advantage of anti-interference and high angular resolution. DMS-SWOTHR is a complex and delicate system. It works on the difference between target echo and interference in Doppler element. So it is a great challenge to develop DMS-SWOTHR. In this paper, DMS-SWOTHR explores on sea as the research background. The main researches are about how to transform moving distributed arrays to a virtual array with large aperture, and to get the DOA of targets. It Includes DMS-SWOTHR model and received signal, DMS-SWOTHR virtual interpolation array reconstruction, the high resolution DOA estimation, DMS-SWOTHR GUI.Firstly, this paper introduces the development of DMS-SWOTHR at home and abroad. Then this paper introduces the relevant theoretical knowledge of high resolution DOA estimation algorithm, including MUSIC algorithm, symmetric matrix method refactoring and spatial smoothing algorithm, the optimal beam-forming theory.Then we talk about how to reconstruct the arrays of DMS-SWOTHR to virtual array, what is the main content of this article. Based on the structural feature of moving array, this paper puts a pre-estimation-based VIA transform method. And the structure of DMS-SWOTHR is analyzed, including arrays baseline Angle, distance, the influence of the Doppler Effect. From the max distance, the relative velocity and the angle of baseline, we analyze the conditions of reconstruction, within a certain error range. We discuss in details how to determine the baseline of virtual array position, and how to set up a virtual array element number, and get a reasonable range.In addition, we get the DOA of targets by pre-estimation-based VIA transform method and high resolution DOA estimation algorithm. In this part, we describe the DMS-SWOTHR model at first. By the spatial smoothing and covariance matrix reconstruction algorithms, MUSIC is estimated respectively. Because the noise matrix of the virtual array is not symmetric positive definite matrix, it can’t do the bleaching process in advance. Increasing the number of spatial smoothing sub-matrix can reduce the noise. Then we make simulations for the optimal beam-forming based on virtual interpolation reconstruction. We make simulations in first-order sea clutter interference and space color noise environment by spatial smoothing MUSIC algorithm, and get the DOA estimation. At last, we design the DMS-SWOTHR GUI.