Research On Angle Estimation Algorithm Based On The Distributed Nested Array

In recent years,a new distributed array sparse radar composed of multiple divided small aperture arrays has become the focus of the radar field due to its flexible mobility,good performance of angle estimation and high stability.Because of the dispersion of the subarray of the array,the large aperture of the array can be realized,and the performance of angle estimation can be improved obviously.However,due to the large spacing of the subarrays and not satisfying the Nyquist sampling theorem,the angular ambiguity affects the performance of angle estimation.In addition,the number of sources that can be estimated does not increase.Therefore,this dissertation mainly focuses on the the angle estimation algorithm of distributed array radar.The main details of this dissertation are as follows:Firstly,with the distributed array as the object,the array structure and signal model of distributed array are studied and the pattern of distributed array is deduced according to its structural characteristics.Two traditional DOA estimation methods based on MUSIC and ESPRIT are expounded amply.Moreover,the effect of grating lobe characteristics on the performance of DOA estimation of the distributed arrays is verified by MATLAB simulation.Secondly,the degree of freedom and resolution of DOA estimation for distributed array are studied.The nested array structure is applied into the existing distributed array radar subarray and an array structure of the distributed nested array is proposed.Meanwhile,according to the characteristics of array structure and signal model,the DOA estimation method based on multi-scale ESPRIT and the DOA estimation method based on pre-processing weighted signal subspace MUSIC are proposed.Theoretical analysis and MATLAB simulation show that these methods can effectively increase the degree of freedom and enlarge the aperture of the array.Both methods lead into short baseline DOA estimation based on the advantage of array,which can improve the precision of reference estimation through multi-layer deblurring,so that the performance of the final long baseline DOA estimation is better.Finally,the joint estimation method of DOD and DOA for bistatic distributed nested array MIMO radar is studied.Combining the advantage of distributed nested array withbistatic MIMO radar,an array structure of bistatic distributed nested array MIMO radar is proposed,and a high-precision angle estimation dual-scale ESPRIT based on the angle disambiguation method by information of targets is proposed.Theoretical analysis and MATLAB simulation show that the proposed method can achieve the virtual expansion of the short baseline and the long baseline of the array without increasing the hardware complexity,and improve the super resolution and angle estimation accuracy of the system.Moreover,the additional pairing algorithm is doesn't need for DOD and DOA estimation using proposed method,which further improves the performance of the algorithm and the resolution of the target.