Research On ISAR Imaging Based On MIMO Technology

Radar imaging technology is an important way to obtain more abundant information for reconnaissance and identification under the information warfare conditions.Inverse synthetic aperture radar(ISAR)imaging is one of the typical methods for imaging moving targets,but with non-cooperative targets stealth technology,ultra-high-speed penetration,electronic interference and anti-radiation weapons and other anti-radar means more advanced,traditional ISAR imaging performance and even battlefield survival for radar itself is severely challenged.At the same time,array signal processing technology,which is represented by multiple input multiple output(MIMO)technology,provides an opportunity to make up for the deficiency of traditional ISAR imaging.MIMO technology applied to ISAR can improve ISAR battlefield survivability,robustness and imaging performance.However,there is no mature theory for the overall structure and imaging algorithm of MIMO-ISAR system.Therefore,the related problems of MIMO-ISAR imaging are studied in this paper.The main contents and major innovation of this paper are as follows:Firstly,based on the detailed analysis of MIMO system and ISAR imaging technology,design of orthogonal phase coded signals based on simulated solidification-iterative algorithm(SSIA)and the combination of phase encoding and linear frequency modulation(PCM-LFM)design are proposed.Through the calculation and analysis of the orthogonality and resolution performance of the designed waveform,it is proved that the proposed waveform has better performance than the traditional waveform.The MIMO-ISAR array based on the phase center approximation(PCA)principle is studied.The theoretical analysis shows that the MIMO system can produce more virtual elements than the actual physical elements,and the constraints of the principle are given.Secondly,on the basis of the overall structure of the system,combined with the basic characteristics of MIMO and ISAR and the motion model of the target,the problem of echo disorder caused by the spatial separation of MIMO system is studied,and the MIMO-ISAR system echo sorting and rearrangement,and spatial spectrum analysis based on the target motion state are proposed.This paper systematically analyzes the equivalence between space and time in the MIMO-ISAR system which is urgently needed.In addition,in order to solve the motion compensation problem of the moving target under the MIMO system,the motion compensation algorithm of MIMO-ISAR is studied.The envelope-alignment algorithm based on the accumulation-envelope correlation method(AECM)and the Doppler center tracking(DCT)phase correction algorithm are applied,simulation experiments show that this algorithm can achieve better motion compensation effect.Finally,the target velocity estimation method based on the minimum entropy criterion of the image is studied,and the imaging algorithm of interpolation and de-redundancy based on echo data is proposed.The simulation results show the correctness and superiority of the proposed algorithm compared with the traditional ISAR imaging results.