Imaging Of Ground Moving Targets With Airborne SAR

In the recent decades,Synthetic Aperture Radar(SAR)has developed into an advanced microwave imaging radar of high resolution which can work with all-time and all-weather.This technique has been successfully used in civilian and military areas for static ground targets.However,if we use those technologies to process the received signal of the ground moving targets,these will be blurs or smearing in the SAR imaging generally.Therefore,the traditional SAR imaging technologies are no longer applicable to the moving targets.This thesis conducted an in-depth research in SAR imaging of ground moving targets,the main content is as follows:1.A geometrical model of airborne SAR ground moving target is established.This thesis studies the effects of different motion parameters of moving targets on the results of SAR imaging,and reveals the cause of moving target' misregistration and smearing in SAR image through theoretical derivation and analysis.The key techniques of ground moving target imaging of airborne SAR are analyzed.2.The motion compensation method and parameter estimation for airborne broad-side looking SAR are studied.The concept of distance migration are introduced and the calibration standards are analyzed.Two kinds of classical RCMC methods of time domain and frequency domain are introduced.Based on the analysis of the motion error model of broad-side looking SAR,a novel method for raw data based motion parameters extraction and motion compensation is presented.Finally,two methods of parameter estimation which are line fitting method based on instantaneous Doppler frequency and motion parameter estimation based on search of global minimum are introduced,and the effectiveness of this approach has been verified by the simulation results.3.Based on Doppler parameter estimation of ground moving target,the classical time-frequency analysis is studied,the SWVD time-frequency analysis is presented,this distribution has high time-frequency resolution without disturbance of cross-terms.An airborne SAR moving target imaging method based on the Wigner-Ville distribution(WVD)is introduced.Based on multi target imaging problem for large scenes and low azimuth resolution,an airborne SAR moving target imaging method based on the cross Wigner-Ville distribution(SWVD)is proposed,this proposed algorithm can get better focusing performance of imaging compared with the traditional algorithm by the simulation results.