Research On Bistatic SAR-GMTI Clutter Suppression Methods Based On Sparse Recovery

Bistatic synthetic aperture radar(Bistatic SAR,Bi SAR)is a new SAR system in which the receiver and the transmitter are placed on different platforms.Compared with monostatic SAR,it can not only provide high-quality forward/backward images,but also has strong concealment and high anti-interference.Therefore,Bi SAR has very important research value and application prospects in the fields of military and national economy fields.In addition to providing high-quality scene images,Bi SAR can also be combined with Ground Moving Target Indication(GMTI)technology to detect and identify moving targets to meet the demand for situational awareness of moving targets.Clutter suppression is a key link in the realization of Bi SAR-GMTI.Bi SAR-GMTI clutter suppression based on sparse recovery technique refers to using the sparsity of ground stationary clutter in the space-time domain,and through signal processing methods to solve the clutter suppression performance degradation caused by the nonstationary and inhomogeneous characteristics of Bi SAR-GMTI clutter.It can effectively suppress non-stationary and inhomogeneous clutter and build the foundation for detecting ground moving targets.In this thesis,related theoretical research and simulation verification are carried out around Bi SAR clutter modeling,characteristic analyzing and clutter suppression method based on sparse recovery.The main contents are as follows:1.The Bi SAR space-time clutter modeling method based on non-standard elliptical coordinate transformation is researched,and the range migration,non-stationarity and space-time sparse characteristics of Bi SAR-GMTI clutter are analyzed,which lays a theoretical basis for the research on sparse recovery clutter suppression methods.2.The clutter suppression methods based on atomic norm minimization and local search orthogonal matching are studied.The limitations and main problems of the above methods in Bi SAR-GMTI clutter suppression are pointed out.3.A Bi SAR-GMTI sparse suppression method based on atomic optimally searching is proposed.From the perspective of atom searching,through power spectrum dimensionality reduction,the global search is performed first and then the local optimal search method is used to solve the problem of long search time and poor atomic position accuracy,which suppress the Bi SAR-GMTI clutter effectively.4.A Bi SAR-GMTI sparsity suppression method based on clutter ridge matching is proposed.From the perspective of dictionary reconstruction,an overcomplete dictionary effectively matched with space-time clutter ridges is reconstructed according to the prior information,which solves the problem of sparse recovery performance degradation caused by off-grid problem.This method realizes the effective suppression of nonstationary and inhomogeneous clutter,which guarantees well performance in moving target detection.The effectiveness of the above methods in this thesis is verified by theoretical analysis and numerical simulation and experimental data processing.The results illustrate that these proposed methods can suppress the Bi SAR-GMTI non-stationary inhomogeneous clutter effectively.