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Airborne Maritime Radar Based Submarine Periscope Detection and Discrimination at High Grazing Angles

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Sensors & Electronics Technology

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AntiSubmarine Warfare, High Grazing Angle, Periscope Detection and Discrimination, Radar


Maritime wide area surface search radars have traditionally operated at low altitudes (=300 m.) and utilized short coherent integration times (most non-coherently). These designs provide for rapid updates and good clutter performance at low grazing angle where mean clutter levels are low but where sea spike returns are routinely larger than target returns. The non-coherent radar return characteristics of sea clutter at low grazing angles (


The objective of this RTG is to advance the level of knowledge across all participating RTG members in the area of radar-based high-altitude submarine periscope detection and discrimination. Specifically, the RTG should address key aspects of the high altitude periscope detection and discrimination problem to facilitate its development and fielding by participating nations.


1. Document expected submarine mast exposure discipline as a function of submarine type, patrol objectives, patrol area, patrol phase, surface sea state and crew proficiency. Mast type, exposure height and exposure duration are critical inputs to airborne radar mode design and tactical usage. Perform analytical, numerical and experimental analysis of submarine mast radar cross sections as a function of grazing angle, mast(s) configuration and exposure, surrounding sea state, look direction relative to the sea and radar operating frequency. In order to gain insight into the scattering mechanisms, the initial analyses will consider simple structures such as metallic cylinders and elevated spheres as submarine mast surrogates. Multipath scattering from the surrounding sea surface has a significant role in apparent radar scattering cross section of the submarine mast. 3. Perform analytical, numerical and experimental analysis of the submarine mast detection techniques. Candidate techniques include single and multichannel coherent processing, sparse signal separation approaches, time-frequency analysis and machine learning based approaches. The objective is to improve high grazing angle detection performance and provide front-end false alarm mitigation (prior to potential back-end mast discrimination/classification) in the presence of sea clutter (including sea spikes) and flotsam. 4. Perform analytical, numerical and experimental analysis of mast signature discrimination techniques to separate masts from unassociated sea clutter and flotsam returns as well as returns from other man-made objects such as buoys and small boats. A variety of candidate techniques for discriminator development will be considered including first order logic based expert systems and machine learning approaches. 5. Prepare general mode design guidelines for high grazing angle submarine mast detection and discrimination for various radar hardware configurations including fixed-beam mechanically scanned radar systems, single and multiple fixed AESA radar systems and single panel gimballed AESA radar systems.

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