Along-Track Interferometry for Simultaneous SAR and GMTI: Application to Gotcha Challenge Data

This paper describes several alternative techniques for detecting and localizing slowly-moving targets in cultural clutter using synthetic aperture radar (SAR) data. Here, single-pass data is jointly processed from two or more receive channels which are spatially offset in the along-track direction. We concentrate on two clutter cancelation methods known as the displaced phase center antenna (DPCA) technique and along-track SAR interferometry (AT-InSAR). Unlike the commonly-used space-time adaptive processing (STAP) techniques, both DPCA and AT-InSAR tend to perform well in the presence of non-homogeneous urban or mountainous clutter. We show, mathematically, the striking similarities between DPCA and AT-InSAR. Furthermore, we demonstrate using experimental SAR data that these two techniques yield complementary information, which can be combined into a "hybrid" technique that incorporates the advantages of each for significantly better performance. Results are generated using the Gotcha challenge data, acquired using a three-channel X-band spotlight SAR system.