Study Of Moving Target Imaging Method On High Resolution Wide Swath SAR

With the continuous development of SAR imaging system,imaging requirements are also rising,and now requires SAR system with high resolution and wide swath(HRWS)imaging capabilities.The traditional single-channel SAR can't meet these two indicators at the same time,the new multi-channel system can provide the solution.Through effective multi-channel signal processing,it can cover a wider swath at the same resolution.The ground moving target identification(GMTI)under HRWS condition is of great concern.Therefore,it is very meaningful to study the effective solution of HRWS-GMTI.In this paper,HRWS-GMTI is studied,and the suppression of clutter,the prediction of moving target velocity and the suppression of moving target ambiguity are analyzed.The solution of these problems is studied and the feasible moving target imaging method is designed.The main tasks include:1.The multi-channel echo signal of the clutter and moving target is deduced and compared with the signal model.And the clutter suppression is carried out by using the displaced phase center antenna technique(DPCA).And the phase difference of the multi-channel echo is given.The process of channel correction and clutter cancellation is given,and the effect of clutter suppression is verified by simulation.Then,by analyzing the shortcomings of DPCA,the clutter suppression method of space time adaptive processing(STAP)is introduced.The principle of STAP and its application in multi-channel SAR system are introduced.The simulation results show that the clutter suppression and compared with the DPCA method.2.The method of estimating the moving target speed is studied.Firstly,the minimum entropy method based on DPCA clutter suppression is introduced to estimate the moving target velocity,and the realization process of the method is summarized.Then,in the STAP clutter suppression method,the moving velocity estimation method of Lv's Distribution(LVD)is introduced.The principle of the method is introduced and the performance of the two methods is compared.3.In the HRWS model,it is necessary to suppress azimuth blurring in order to achieve moving target high resolution imaging.This paper introduces the traditional multi-channel reconstruction method,and uses the estimated target speed based on the Doppler frequency offset of the moving target,which is applied to the reconstruction of the moving target and the suppression of the moving target ambiguity.It also introduces a further improved multi-channel reconstruction method to solve the problem of singularity of transfer function matrices in moving target reconstruction.4.Analyze the feasibility of applying the LVD method to the HRWS model,and transfer the coordinate of the original method to deal with the data after the clutter suppression.The influence of the azimuth velocity on the imaging is analyzed,and the moving velocity of the moving target is estimated by LVD,and the image quality is improved by the improved imaging method.