Three Dimensional ISAR Autofocus based on Sparsity Driven Motion Estimation

Inverse Synthetic Aperture Radar (ISAR) exploits the motion of the target to achieve cross range imaging, as opposed to its range resolving capability (along line of sight) which relies on the bandwidth of the signal. In ISAR imaging, it is usually the case that the relative motion between the radar and the target of interest is unknown. The lack of precise knowledge of this relative motion affects the quality of the reconstructed image. Therefore, estimating the relative motion is an essential step for ISAR imaging. Compared to the two dimensional ISAR, the three dimensional ISAR imaging requires more motion components to be estimated. In this paper we present a sparsity driven algorithm that tackles the problem of three dimensional ISAR auto-focusing based on relative motion estimation.