Multiple moving targets ISAR imaging based on discrete match fourier transformation

When multiple moving targets are close to each other, the returned signals from these targets are overlapped in time. Therefore, by applying conventional motion compensation algorithms designed for single target, the multiple targets cannot be resolved, and individual one cannot be clearly imaged. However, each individual target may have its own velocity different from others. The translational motion can be viewed as a uniformly accelerative motion, so the Doppler variation of echoes in cross can be approximated by a first-order polynomial which is called linear frequency modulation signal. For different targets, the chirp rates are different from each other. In this paper, a new algorithm based on discrete match Fourier technique is proposed to separate the signals from different target in each cross-range cell. By the CLEAN technique, the number of targets need not be appointed. We use envelop correlation and PGA algorithms to compensate the motion of each target signals, then the image of each target can be obtained by applying Range-Doppler algorithm. The results of computer simulation are given to show the efficiency of the proposed algorithm for multiple moving targets imaging.