Spaceborne radar imaging of maritime moving targets with the Cosmo-SkyMed SAR system

Advanced satellite synthetic aperture radar (SAR) systems, such as Cosmo-SkyMed (CSK), provide high-resolution images with reasonably short revisiting time, allowing for a number of applications in areas such as homeland security and maritime surveillance. Especially in the case of maritime surveillance, moving targets imaging represents a challenge for SAR systems as the complex target motions produce evident image defocusing. In this paper, we propose a complete processing chain that aims at detecting and imaging ship targets moving inside the imaged scene. In the proposed technique, moving targets are focused by using inverse SAR (ISAR) processing, which proves effective also in the case of target's complex motions. The implemented processing chain can be considered an innovative combination of well-established detection and ISAR imaging approaches. It is important to state that the proposed maritime ISAR mode for the CSK SAR system acts as an add-on system and, therefore, does not require any modification to the original CSK design. The effectiveness of the proposed approach is demonstrated by processing archive images acquired by CSK in spotlight mode; moreover results obtained by using CSK images acquired ad hoc against a cooperative target are also provided in order to prove the validity of the overall chain also in presence of targets with small size. As additional option of the proposed maritime ISAR it will also be shown that super-resolution techniques are applicable to targets affected by complex motions after ISAR processing is used. © 2014 IEEE