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Activity title

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 group should address key aspects of the high altitude periscope detection and discrimination problem to facilitate its development and fielding by participating nations.


Among the candidate questions to be addressed by the RTG include: What are the Doppler characteristics of the sea and of submarine periscopes/masts? How do the electromagnetic scattering characteristics of periscopes (single or multiple masts) change from low grazing angles to higher grazing angles and can this be leveraged for detection and discrimination? How are longer coherent processing intervals used for long range detection and/or improved sensitivity balanced with area revisit rates for both MSA and AESA based radar systems? How do we best leverage the Doppler dimension for discrimination to improve the ability to separate target from clutter, wakes and spray? How does performance scale with choices in Doppler resolution where we expect that the ocean clutter energy can be spread across multiple Doppler bins while the periscope’s Doppler response will produce a narrow Doppler response? Are false alarms from the spikiness of clutter reduced by decorrelation across longer coherent processing intervals? What is the optimum range-Doppler CFAR design? How does performance change as a function of grazing angle, sea state, look direction relative to the seas, swell, periscope/mast exposure time, exposure height and radar cross section?

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