Relative Speed Step Size in SAR processing for Moving Target Detection

Abstract

Ground moving target indication (GMTI) using synthetic aperture radar (SAR) is studied in this paper. For systems using long integration time relative speed between the target and the SAR platform has to be included in the detection algorithm. A separation between the true relative speed and the relative speed used in the SAR process will cause unfocused targets. Unfocused targets decrease the detectability. In the detection phase of SAR moving targets blind hypothesis on relative are used. The step size between the hypotheses or the quantization step in relative speed is a trade off between the number of hypotheses to test and detectability. A large number of tests will increase detectability but will also increase computation load and vice versa. The importance of relative speed increases as the azimuth integration time gets larger. Long integration time is associated with low signature moving targets detection in strong clutter environment and especially for SAR GMTI at low frequencies. In this paper we determine the optimum quantization of relative speed for moving target detection. The optimum quantization is derived from the moving target impulse response. By using the optimum quantization the computation burden in SAR GMTI is reduced and the detectability secured