Real Time Rotational Motion Compensation algorithm for focusing Spot-SAR / ISAR images in case of variable rotation-rate

摘要

The problem of compensating image blurring induced by target rotation in Spot-SAR/ISAR imaging is investigated. Oppositely to what is generally assumed, the case of a variable rotation-rate during coherent processing time is considered since this usually happens in forward looking SAR geometry as well as in aircraft or ship ISAR imaging. A novel algorithm is proposed to solve the addressed problem with particular emphasis given to a possible mechanisation for real-time applications. To this respect, the performance in terms of required computational load is analysed. The concept of the proposed algorithm is derived by a suitable simplification of the SAR/ISAR signal phase equation. The effectiveness of the proposed algorithm is verified also by processing real radar data acquired during extensive flights campaign: the dramatic improvement, with respect to traditional techniques, demonstrates the effectiveness of the proposed approach.