Robust method for the motion compensation of ISAR imagery

A technique for improving stepped-frequency inverse synthetic aperture radar (ISAR) imagery via entropy minimization is presented. Image improvement is achieved in the frequency domain where the echo phase can be adjusted to compensate for radial motion. The computational algorithm which determines motion parameters that reduce entropy to an absolute minimum is based on the golden-section-search method and operates in a closed-loop mode. Using this technique one can efficiently focus the image generated by a fully automated high-resolution-radar system that evaluates its own performance in terms of image quality.