Robust Towed Array Beamforming

Even when built to exacting standards, towed arrays invariably suffer acoustic sensor failures. A relatively small number of sensors can have large negative impact on beamformer side-lobe levels. This SBIR program will develop, implement, and integrate atowed array beamformer shading algorithm that provides robust performance as hydrophones fail. The selected algorithm must provide better acoustic performance than current conventional shading, operate within the structure of existing beamformerprocessing, and execute in affordable computer resources. We will evaluate two classes of solutions to this problem: 1) data independent, and 2) data dependent. Data independent methods are usually much less computationally expensive. Data dependentalgorithms are typically more expensive than data independent methods, because sensor weights must be continuously adjusted based on real-time sensor data. However, these algorithms also have much greater performance recovery potential. Our approach forPhase 1 algorithm selection entails an Analysis of Alternatives. This analysis will consider the following factors: (1) Quantitative Acoustic Performance; (2) Computer Resource Requirements; (3) Implementation Complexity and Cost; (4) Systems IntegrationComplexity and Cost. These tradeoff criteria will be evaluated collectively to make an appropriate algorithm selection decision. This SBIR technology will provide improved array gain performance and increased operational availability for towed array sonarsystems. Potential commercial applications include seismic survey systems that employ multi-line towed acoustic streamers.