Synthetic Aperture Radar Moving Target Detection And Imaging Studies

Moving Target Detection and Image (MTDI) is a hot topic in the area of Synthetic Aperture Radar (SAR) and plays an important role in both martial field and civilian field. Now many countries in the world are making great efforts to develop MTDI systems and explore high efficient MTDI algorithms.This dissertation studies thoroughly the key techniques of MTDI, makes an improvement on it in order to get high detection probability and good image of moving target and presents several novel MTDI approaches that are more efficient and useful in practice. The major devotement of this dissertation is as follows.1. After analyzing the theory of MTDI and setting up the model of moving target echoes, the dissertation discusses in detail the effect of moving target Doppler center frequency and Doppler rate on the conventional SAR image. It also analyzes detailedly the range migration of moving target from time field and frequency field and provides migration model in both fields. After that, it divides algorithms of MTDI into several classes, analyzes the influence of signal-to-noise on the detection results and gives the flow chart of moving target imaging processing.2. The dissertation uses spectral-filter method to detect moving target in the real echoes received from an airborne SAR system. It combines the real echoes with the date simulated using the real airborne SAR system parameters to analyze and validate the method. After the combined data are filtered, the improved greatest of cell-average constant-false-alarm-rate (GO-CA-CFAR) is used to judge whether moving target is detected or not. In the following, real moving target is detected and its velocity and position is gained through which it is focused well.3. After studying deeply the multi-antenna SAR MTDI based on displaced phase center antenna (DPCA), a new double-antenna method is proposed which remedies the shortcomings of conventional ways. The method needn't meet the constraint condition that conventional ways must meet and can suppress ground cluttereffectively and detect moving target. Then its mathematical model is set up and its validity is proved by computer simulation results. In the following, a new processing method of using three-antenna to detect, locate and image moving target is proposed based on DPCA and interferometric theory. This method can not only suppress ground clutter effectively and detect moving target but also locate accurately azimuth position of moving target and estimate its velocity. The detecting and imaging processing scheme is presented and described detailedly. The typical computer simulation results are given and illustrate its validity. Some problems such as receiving channels mismatch and blind speed are discussed and solved.4. The dissertation studies in-depth the multi-aperture SAR MTDI based on along-track interferometry (ATI). It presents and describes the detecting processing in SAR image domain using double apertures and analyzes the influence of all kinds of factors including ground clutter, noise, signal-to-clutter, range velocity, multi-look processing and etc on the detection performance. To remedy its shortcomings, a new processing method in range-Doppler domain to detect moving target is proposed. The detecting processing scheme is presented and described at length. The method can detect moving target more effectively as is validated by computer simulation results. The dissertation also gives another interferometric processing method using three apertures to detect, locate and image moving target and describes its processing scheme.