Small, Low-Power, Low-Cost 2D Beamformer for Portable Imaging Sonar

The need for multiple, cost-effective deployments of undersea acoustic mine-field reconnaisance and mine hunting systems requires the development of light-weight, low-power, low-cost, high-resolution sonars. These imaging sonars should be portable enough for use in a diver's hands, in a remote imaging sonar on an unmanned undersea vehicle or with a small surface-craft sonar. To achieve these goals, a beamformer capable of forming 100 simultaneous beams on a single low-cost, low-power chip is proposed here. A 100 element two-dimensional array, when used with the proposed beamformer, would produce a real-time 10 by 10 or 100-pixel image. In this way, a detailed image could be formed to search for mine like objects. Obstacles in the vehicles path could be detected and a path to circumnavigate obstacles determined. Areas of interest could be discriminated from clutter in littoral waters. The proposed 2D beamform chip is implemented based on our proprietary CDP technology. The computation power offered by this technology allows a 2D computing algorithm to be efficiently mapped onto a single-chip device. As a result, the chip can support a continuous throughput rate of 14 billion multiply/accumlate operations per second with an estimated power dissipation less than 2 Watts. Compared with a state-of-the-art DSP, Analog Devices' SHARC processor, the proposed 2D-beamforming device provides more than two-orders-of-magnitude power and weight savings when compared to the conventional imprlementation.