Sparse array technology for 3‐D sonar imaging systems

A three‐dimensional sonar imaging system is under development for use by Navy divers for mine‐field reconnaissance and mine‐hunting systems. Divers require a small, low‐power, lightweight acoustic imaging system with high resolution for examining and disposing of underwater ordinance. Sparse array technology is investigated to develop a sonar requiring the minimal number of signal processing channels while maintaining the beamwidth and sidelobe structure required for high‐resolution imaging. Beamwidth and sidelobe structure are examined as a function of transducer element count, channel bandwith, and element location when optimized using various cost functions. Locally optimum solutions are computed for uniformly weighted sparse arrays. Cost functions evaluated for the optimization process compute average sidelobe energy, peak sidelobe energy and a weighted average sidelobe energy. Images will be formed using multiple CCD/CMOS time‐delay beamforming circuits to compute the large number of beams required t...