Research On Detecting And Imaging Of Moving Target With Airborne Synthetic Aperture Radar

The technique of moving target detection and imaging by Synthetic Aperture Radar (SAR) is very important in military area. The moving target's radar images can provide valuable information. It's very pivotal that the Doppler parameter should be accurately estimated; Ground Moving Target Indication (GMTI) mode of SAR can fulfill the tasks of war zone search and pre-alert. It can provide images of covered area and senses moving targets at the same time. Single-channel SAR system, i.e. system with one receiving antenna, has the advantages of lower hardware effort, less computational load for data processing, and lighter weight. So it's very suitable for low altitude unmanned aircrafts flying fast. Many research institutes in China have gained many achievements on different aspects in SAR area and accomplished several tests of SAR. This paper focuses on moving targets imaging and indication of SAR/GMTI mode and has a deep search on it. It gives a systematic method of SAR moving targets imaging and indication, and put forward some innovations on some pivotal problems. This paper finally shows the results by processing the raw data and some works fill up the blank of radar area. The author brings up a method by research to get clearer image for moving targets by dechirping the frequency rate of them and to relocate the moving targets in radar image by moving the Doppler spectrum. The task of estimating Doppler parameter is a pivotal task of SAR signal processing. This paper brings up an improved method of Doppler centroid Estimation: improved energy balancing method. This method is precise and it can compute the Doppler centroid without iterative computations, so it is more suitable for real time processing on DSP and has higher efficiency. This paper shows the new method's results by processing the raw data and analyzes its performance. This paper put forward that the SAR processing method which includes range cell migration correction technique and azimuth dechirping technique can improve image quality effectively in DBS imaging when on SAR/GMTI mode. At last, some satisfying images by DBS based on the raw radar data are presented. This paper gives a systematic way to fulfill the task of single-channel SAR/GMTI and brings forward several effective method in different aspects including constant false alarm rate, estimation of moving targets'parameter and plot-track association processing. At last, it completes the whole research of the task. This paper finally summarizes the research work, and discusses those potential research topics in future.