wide area maritime surveillance. Even platforms that we typically think of as operating at low attitudes such as manned and unmanned helicopters prefer to fly at 1 to 2.5 km altitude rather than the 150 to 450 m required for traditional periscope detection radar modes. Submarine periscope detection has always been one of the most challenging radar problems. A well-disciplined submarine crew will limit exposure times to less than 10 seconds when in attack postures. The development and fielding of low-profile photonics masts allow operators to pop up for very short periods of time and record multispectral 360-degree images in visible light, low light, and infrared.

Lacking a capability to counter this threat places ships at significant risk.

 

The desired operational capability would balance the periscope detection and discrimination performance from high altitudes with the instantaneous area coverage needed to respond to the short periscope exposure time. While it is expected the approaches will be applicable to older, fixed-beam mechanically-scan radar systems (MSA), those radar systems using agile beam active electronically scanned antenna systems (AESA) will likely be most suited to this solution. This SBIR topic seeks to develop robust techniques to exploit mast signatures so that they can be separated from those of other man-made and environmental returns. The balance between detection/discrimination performance and area coverage should be assessed in a variety of conditions and characterized through receiver operating characteristic curves. A variety of candidate techniques for discriminator development will be considered including first order logic-based expert systems and machine learning approaches.

 

Work produced in Phase II may become classified. Note: The prospective contractor(s) must be U.S. owned and operated with no foreign influence as defined by DoD 5220.22-M, National Industrial Security Program Operating Manual, unless acceptable mitigating procedures can and have been implemented and approved by the Defense Security Service (DSS). The selected contractor and/or subcontractor must be able to acquire and maintain a secret level facility and Personnel Security Clearances, in order to perform on advanced phases of this project as set forth by DSS and NAVAIR in order to gain access to classified information pertaining to the national defense of the United States and its allies; this will be an inherent requirement. The selected company will be required to safeguard classified material IAW DoD 5220.22-M during the advanced phases of this contract.

 

Although not required, it is highly recommended to work in coordination with the original equipment manufacturer (OEM) to ensure proper design and to facilitate transition of the final technology into currently fielded Navy maritime surveillance radar systems such as the APY-10, ZPY-3, APS-153, ZPY-8, and the ZPY-9.

 

PHASE I: Perform analytical and numerical analysis of representative but simplified submarine mast shape 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, initially consider simple structures such as metallic cylinders and elevated spheres as submarine mast surrogates. Explore the role of multipath scattering from the surrounding sea surface in apparent radar scattering cross section of the submarine mast. Show how this scattering behavior and associated prototype detection techniques such as single and multichannel coherent processing, sparse signal separation approaches, and time-frequency analysis could be leveraged to discriminate mast signatures from other objects on the sea surface. The Phase I effort will include prototype plans to be developed under Phase II.

 

PHASE II: 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. Complete development of the prototype system and evaluate its performance over a range of conditions using a combination of synthetically generated datasets and Government-provided field data.

 

It is probable that the work under this effort will be classified under Phase II (see Description section for details).

 

PHASE III DUAL USE APPLICATIONS: Mature and test the mode on transitioning Navy airborne maritime surveillance radar systems (cited above) in coordination with the radar systems� OEM.

 

Techniques might be applicable to commercial satellites surveilling ocean environments and seeking to detect small boats. Both users of commercial satellite synthetic aperture radar data and providers of the data (e.g., Capella, RadarSat, TerraSAR-X and COSMO-Skymed) would be beneficiaries.