Robust Towed Array Beamforming

The overall objective of this SBIR program is to provide robust towed array beamforming when increasing numbers of hydrophones become inoperative. Digital Systems Resources (DSR) proposes to explore multiple techniques, both conventional and adaptive, aswell as a recently published innovative approach developed at DSR.To accelerate transition of the proposed technology into Navy fleet systems, DSR will use the SURTASS production software as a testbed to verify the proposed techniques. We will also develop system specifications and requirements for each method toprepare for easy transition to the production system on an accelerated schedule.At DSR, Shapo and Bethel have pioneered a new ABF method. The new technique, Spatial Processing: Optimized and Constrained (SPOC), seeks the minimum energy plane wave set that coherently accounts for all the energy at each sensor. This criterion for theadaptive weights is a departure from traditional ABF methods, which perform noise minimization at the beamformer output. This method has been highly successful with simulated data and shows great initial promise with at-sea acoustic data.All the work described above is quite general in its approach to beamforming. The option task will extend each of the previous tasks to include the twinline array. Successful completion of the Phase I and II work will result in technology that merits inclusion in existing SONAR processing systems. The primary candidate system is the SURTASS program but this work also could directly benefit other passive platformssuch as submarine and surface ship towed array systems, as well as active programs including the AN/SQQ-89. The anticipated beamformer benefits will pay dividends not only for the SONAR operator via improved broadband and narrowband displays but also byproviding improved performance for downstream automation processing including target detection, tracking, and classification. Advanced array processing, implemented in portable software for execution on low-cost commercial hardware, will result in majorcapability improvement for the target SONAR systems. Finally, the techniques investigated here could apply to other kinds of sensor array systems including RADAR and medical imaging.