Research Of Airborne Hight Resolution SAR Imaging And Location Techniques

The unmanned aerial vehicle(UAV)platform is small and inertial.The platform is easy to shake during flight.So it is difficult to obtain high-resolution images by relying on the classical algorithm only.The high-resolution SAR imaging algorithm and location technology in view of the characteristics of small size and large jitter in the low and middle altitude airborne radar have been studied in this thesis.The measured data has been utilized to study the parameter estimation and motion compensation based on the R-D algorithm so that the algorithm can better adapt to the UAV platform and obtain higher resolution images.The Doppler center frequency is estimated by correlation function method.The estimation of Doppler frequency modulation is obtained by iterative Map Drift(MD)algorithm,and the motion compensation based on echo data is used to compensate the envelope and phase of the carrier track in the normal plane and heading direction.Experiments show the effectiveness and necessity of Doppler parameters estimation and motion compensation.The resolution of the obtained SAR images are 0.5m by our method.SAR location should transform the coordination of the target in the image into terrestrial coordinate system.The relationship between the different coordinate systems used by SAR location is studied and the transformation method is given,which is essential for SAR location.The principle of the R-D constellation model is analyzed and the calculation of the model from the mathematical point of view is given.The experimental results by simulation data show that the location results are sensitive to the terrain and attitude angles.In order to improve the location accuracy,the calculation steps of R-D algorithm based on digital elevation map(DEM)is studied.The accuracy of location model is proved by measured data experiment.The location error of proposed strategy can meet the application requirement without DEM.