Accession Number : ADA335304

Title :   Underwater Acoustic Imaging: A Computing Hardware Approach to Rapid Processing

Descriptive Note : Technical note

Corporate Author : DEFENCE SCIENCE AND TECHNOLOGY ORGANISATION CANBERRA (AUSTRALIA)

Personal Author(s) : Blair, David G.

PDF Url : ADA335304

Report Date : SEP 1997

Pagination or Media Count : 42

Abstract : High-resolution underwater acoustic imaging using multi-element arrays implies a large computational load. For a three-dimensional viewing volume resolved into 3x10(exp 9) voxels (volume pixels), with 4000 elements, the computations needed are around 9x(1.2x10(exp 13)) floating-point operations. This report develops one of the more promising options for computing the full image. First, parallel computation is used to deal with the different sensor elements simultaneously, when calculating the address of the appropriate instantaneous voltage at the sensor element-or, equivalently, the calculation of the round-trip distance traveled by the acoustic pulse. This calculation requires, in a typical near-field situation, the computation either of a square root or of a fifth degree polynomial. This polynomial allows increased parallelism. Second, the summation in the beamforming is likewise done with a high degree of parallelism. A machine with the above design, with 10(exp 9) clock cycles per second, would compute the entire image in roughly 6 seconds. Cost and availability are not investigated.

Descriptors :   *SIGNAL PROCESSING, *UNDERWATER ACOUSTICS, *SONAR ARRAYS, IMAGE PROCESSING, REAL TIME, ACOUSTIC WAVES, SIGNAL TO NOISE RATIO, PARALLEL PROCESSING, HIGH RESOLUTION, BEAM FORMING, AUSTRALIA, PIXELS, FLOATING POINT OPERATION, SONAR IMAGES.

Subject Categories : Acoustic Detection and Detectors

Distribution Statement : APPROVED FOR PUBLIC RELEASE