Multi-Polarization Inverse Synthetic-Aperture Radar (ISAR) for Automated Ship and Small Craft Classification

RDRTec Inc. and SAIC propose to develop, compare, and test innovative multi-polarization techniques that will both increase the information content in Inverse Synthetic-Aperture Radar (ISAR) images as well as exploit that information to increase the robustness of maritime classification tools that assist sensor operators in rapidly and accurately classifying ships and small boats in the littoral zone. The state of the art in ISAR assisted target recognition uses single polarization image frames. The coherent nature of both SAR and ISAR processing can make it subject to a considerable amount of speckle (or glint of unresolved scatterers) as well as “holes” in the image where the scattering mechanism provides a cross-polarized response to the antenna. Speckle reduction improves the visual quality of SAR and ISAR imagery, and it permits the application of more sophisticated image processing and/or improves the robustness of current feature extraction algorithms. Multiple polarimetric processing techniques have been developed for SAR processing that reduces these problems significantly. If applied to ISAR, these techniques have the potential to significantly improve the quality of the feature extraction and thus classification performance. In addition, different polarization responses are indications of features. For example, if dual circular polarization responses are sampled on receive, resolved scatterers will be separated by channel into even and odd bounce scatterers. This property has the potential to clearly identify the two-bounce scattering at the intersection of the deck and the superstructure from the flat plates of the hull and the superstructure. The proposed work compliments ongoing work being performed by RDRTec and SAIC in the areas of single polarization ISAR and multi-sensor (ISAR and IR) assisted target recognition. Simultaneous dual polarization ISAR data on a small boats and simulated full polarization data will be used in Phase 1 analysis.