Study On High-resolution SAR Ground Moving Target Detection Algorithms

As an extension of synthetic aperture radar(SAR), synthetic aperture radar ground moving target indication(SAR/GMTI) plays an important role in both military and civilian areas. Among all the SAR/GMTI techniques, multi-channel processing has been widely used, since it introduces additional spatial degrees of freedom, which can effectively reduce the minimum detectable velocity(MDV) of the system. However, with increasing resolution of SAR imaging in recent years, range cell migration and azimuth defocusing of moving target in SAR image become more obvious, leading to the decreasing signal to clutter plus noise ratio(SCNR) of moving target that finally causes the performance loss in moving target detection. To address this problem, this paper focuses on the detection performance degradation caused by two-dimensional defocusing of moving target and proposes two new moving target detection algorithms based on the study of classical multi-channel SAR processing techniques. The main contents of this paper are as follows.1 The model of moving target echo is established. Based on that, azimuth displacement, azimuth defocusing and range cell migration of moving target caused by self-motion are analyzed and verified by simulation experiments. After that, classical multi-channel SAR clutter suppression algorithms including clutter suppression interferometry(CSI) and space-time adaptive processing(STAP) are studied in detail, with the performance verified by experimental results.2 A multi-channel SAR moving target detection algorithm based on multi-look processing and combination of amplitude detection and interferometric phase detection is proposed. The major related techniques, i.e., the multi-look processing, along-track interferometry(ATI) and cell-averaging constant false alarm ratio(CA-CFAR) detection are investigated in detail and the advantages of the combination are analyzed. Finally, the effectiveness of this algorithm is verified by a group of measured data collected by a P-band four-channel airborne SAR system.3 A multi-channel SAR moving target detection algorithm based on autofocus and variational threshold CFAR detection is proposed. Autofocus processing is used for reducing the negative effects resulting from defocusing of moving target in order to improve SCNR. CA-CFAR detection with different thresholds also applies to detect moving target and exclude the false alarm respectively. Experimental results show that this algorithm can effectively detect moving target and reduce the false alarm probability sufficiently.