Enhanced Submarine Mast Detection and Discrimination

Radar detection and discrimination of submarine masts is very challenging.  Photonics masts can have a very low radar cross section (RCS), and short exposure times. The surrounding sea is very reflective, masking mast signatures and providing potential confusers that must be discriminated from periscope masts. Airborne maritime surveillance operations have moved toward higher altitudes where they are able to provide wide area intelligence and reconnaissance, improving the probability of illuminating an exposed radar mast but increasing mean clutter levels and reducing spatial resolution, thus impacting the ability to effectively detect and discriminate submarine masts from other man-made and environmental signals. Coherent techniques based on SAR processing may be applied to the problem of detection and discrimination of submarine masts. They provide wide area coverage and are far less sensitive to grazing angle than non-coherent techniques. In addition, they offer improved performance due to a richer set of potential discriminants and the ability to detect moving targets with a wide range of motion paths.  Prior studies suggest that mast wake signatures, with similar total power and wider Doppler spread than the mast hard-body signature, may aid in the detection and discrimination of submarine masts, but the added value under various operating conditions (mast configurations, sea states, submarine speed, direction of movement relative to the prevailing seas and radar viewing geometry) has yet to be quantified. RDRTec proposes to use our Challenging-target Airborne Detection & Discrimination (CADD) testbed, with modifications to detect wake mast signatures, to evaluate the improvement in probability of detection that use of wake signatures can provide to the problem of submarine mast detection.  The CADD testbed has been developed under several prior SBIR topics to support the development and test of challenging target detection modes. CADD provides a common architecture for a wide range of target types, environments, and sensor configurations (multi-pol, multi-static, passive, interferometric).  CADD is a modular system in which front-end processing can be modified for SAR, Doppler Beam Sharpening (DBS), and Real-Beam geometries and initial high false alarm detection is followed by multiple discrimination and screening modules that can be tailored to the detection target of interest.  CADD contains an automated clutter-fitting detector, in which clutter statistical models best matching the imagery are used for CFAR detection and screening, enabling CADD to operate optimally at a range of grazing angles and sea conditions.