Research On Technique Of Airborne Sliding Spotlight SAR Imaging And Motion Error Compensation

Sliding Spotlight Stripmap Synthetic Aperture Radar(SAR)unifies the advantages of wide swath in azimuth for Stripmap SAR and high resolution for Spotlight SAR,and it has advantages in SAR monitoring and mapping field.The dissertation centeres on high resolution of Sliding Spotlight SAR carries on a series of research including theory analytical deduce,signal simulations and processes of real data.The main researches are as follows:The dissertation analyzes the operating principle and signal characteristic for Sliding Spotlight SAR.Based on time-frequency analysis,the system performance parameter and Doppler characteristic are deduced and compared with the former two modes.Aimed on the aliasing of azimuth spectrum for Sliding Spotlight SAR,the dissertation carries on the study of imaging algorithm,up-sampled imaging algorithm and Baseband Azimuth Scaling Algorithm(BASA),and does theory deduction in detail signal simulation.The dissertation validates these two imaging algorithms by real mapping data.To meet the demand of high resolution and to eliminate the effect of instability of airborne platform along the trajectory receiving radar echo,the dissertation does the research of motion error compensation algorithm.Estimating the instant Doppler chirp rate by raw Sliding Spotlight SAR data to obtain the second-order phase error caused by motion error,then compensate it.And the dissertation improve the full-aperture the gradient of high order phase error estimation algorithm based on phase gradient autofocus algorithm.By estimating the full-aperture the gradient of high order phase error to obtain the high order phase error of full-aperture through integral,it will get the Sliding Spotlight SAR fine image to compensate the high order phase error.