Adaptive S-method based ISAR imaging of maneuvering targets

The range-Doppler imaging algorithm is a basic method for ISAR imaging, which is based on the uniform rotation of a target in a fixed plane. For maneuvering target, however, its rotational velocity and the axle often vary with time, so the second-order phase terms are induced to target echoes. Aimed at this situation, an adaptive S-method based imaging algorithm is proposed in this paper. First, translational motion compensation is implemented to the raw data. Then, this algorithm is applied to the echo of each range cell, to eliminate second-order phase terms and obtain ISAR imaging in the range frequency-Doppler domain. Since it only requires complex multiplications and adding, this algorithm has low computational complexity in practical use. In addition, due to the adaptiveness, it can adjust itself according to the returned signals, and reduce the influence of cross-terms for each range cell at the same time. The measured data has proved the validity of this algorithm.