Rotational Motion Compensation Research Articles

Application of adaptive joint time–frequency algorithm for focusing distorted ISAR images from simulated and measured radar data

An adaptive joint time–frequency algorithm has been applied and evaluated for focusing distorted ISAR (inverse synthetic aperture radar) images when the target motion is confined to a two-dimensional plane. It is shown that the adaptive joint time–frequency algorithm provides an effective method of achieving rotational motion compensation for ISAR imaging. Examples provided demonstrate the effectiveness of the adaptive joint time–frequency algorithm with both simulated and experimental ISAR data. Results show that if a target is moving smoothly, standard motion compensation generates a clear image of the target by using the conventional Fourier transform methods. However, when a target performs complex motion such as perturbed random motions, standard motion compensation is not sufficient to generate an acceptable image. In this case, the adaptive joint time–frequency algorithm provides an efficient candidate to resolve the image smearing caused by the time-varying behaviour and leads to a well focused ISAR image when the target motion is confined to a two-dimensional plane. The study also adds insight into the distortion mechanisms that affect the ISAR images of a target in motion.