Study On Compressive-Sensing-Based ISAR Imaging Methods

As an emerging technology of radar signal processing,CS has gained lots of researchers'interests.CS alleviates the problem of large amount of data for high-resolution radar imaging,reduces the hardware complexity of the radar system,and can also deal with incomplete echo data and undersampled data caused by its own or external causes.In addition,the image reconstructed based on CS technology has super-resolution image features and good image contrast.In this paper,ISAR imaging method based on CS technology is studied.The research content is as follows:Firstly,the basic principle of ISAR imaging is introduced briefly,and the principle of CS imaging is expatiated.Then the research status of radar imaging based on CS technology is analyzed.At last,the research background and main research contents are given.A two-dimensional CS image reconstruction algorithm based on SLO is studied.The method reconstructs the range and azimuth of the ISAR image by constructing the two-dimensional CS system function.Comparing with the usual CS image reconstruction method which transforms the two-dimensional signal into a one-dimensional vector,this method reduces the memory consumption,reduces the computation and speeds up the computation time.The effectiveness of the two-dimensional CS imaging method based on the SLO is verified by the processing of the ISAR data.This paper studies the CS method based on KF.The Greedy Kalman Filter algorithm is proposed by combining KF with the greedy algorithm,and the image is reconstructed under the sparse constraint.The results of ISAR data processing verify the effectiveness of the GKF imaging method.The GKF method is superior to other CS imaging methods,e.g.OMP and LARS.The compensation of the target secondary rotation phase component based on CS is studied.Firstly,the MTRC corrections are made to the echoes,and then the observation matrix composed of the quadratic phase is constructed.The target image is obtained by maximizing the image sharpness,and at the same time the target rotation angular velocity can be estimated.The rotational speed is also used for azimuthal image scaling.The results of ISAR data processing verify the effectiveness of the proposed imaging processing method.The imaging quality is improved compared with the image obtained by RDA under the assumption of the linear rotation component with small rotation angle.The evaluation method of CS image quality is studied.Two methods are given which is based on"true value" and based on traditional image quality indicators.The first one is used to evaluate the accuracy of the position and amplitude of the scatter points reconstructed using the CS imaging method.The second one assesses the main objective assessment of image visual effects.The ISAR data of airplane,ship and space object are respectively imaged with GKF,OMP and BCS.Then the two methods are used to analyze the image quality.The analysis results reflect the image quality of each algorithm objectively.Finally,the paper summarizes the results of the thesis and points out the problems that need to be further studied and solved.