Low-Cost Acoustic Cameras for Underwater Wideband Passive Imaging

The imaging of underwater acoustic sources using passive 3-D sonar systems has many potential applications. However, to achieve both wide bandwidth and low cost, an array that is superdirective at low frequencies and aperiodic, to avoid aliasing at high frequencies, is required. To design a sparse array layout and the related filter-and-sum beamformer, a recently proposed method for airborne acoustic cameras is applied. First, the method is generalized to include position errors. Next, the method is used to demonstrate that 49 low-cost, poorly matched hydrophones are sufficient to create a square array for an underwater acoustic camera working from 500 Hz to 8.75 kHz with a side length of 1 m. Finally, the images of a simulated acoustic scenario obtained using different passive systems are compared, which reveals the advantages of the proposed design strategy.