The need for multiple, cost-effective deployment of undersea acoustic mine-field reconnaissance and mine-hunting systems requires the development of light-weight, low-power, high- resolution sonars. These imaging sonars should be portable enough for use in a diver's hands or in a remote imaging sonar on an unmanned undersea vehicle in shallow waters. Under the support of the DARPA Sonoelectronics program, a system that can simultaneously focus many signals using multiple CCD/CMOS, programmable time-delay beamforming circuits connected to a sparsely-populated 2D acoustic array, is being developed. Using this approach, a real-time image could be formed to search for mine-like objects. To make a sparse array practical, the combination of low insertion loss and wide bandwidth performance is critical to realizing acceptable imaging performance with low illumination levels. In this system, a 20 cm diameter 2 MHz sparse array providing a 0.21 degree main beamwidth is proposed. Using this array, a real-time 2D cross-sectional scan of 128 X 128 pixels is achievable with a down-range and cross-range resolution of approximately 1 cm at a range of 3 m. In this paper, the signal-to-clutter ratios as a function of array bandwidth and sparse-array elements placement are presented. Furthermore, the performance of a CCD/CMOS subarray processor will be reported.

Date Published: 23 July 1999
PDF: 11 pages
Proc. SPIE 3711, Information Systems for Navy Divers and Autonomous Underwater Vehicles Operating in Very Shallow Water and Surf Zone Regions, (23 July 1999); doi: 10.1117/12.354666

Published in SPIE Proceedings Vol. 3711:
Information Systems for Navy Divers and Autonomous Underwater Vehicles Operating in Very Shallow Water and Surf Zone Regions
Jody L. Wood-Putnam, Editor(s)