
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 : Highresolution underwater acoustic imaging using multielement arrays implies a large computational load. For a threedimensional viewing volume resolved into 3x10(exp 9) voxels (volume pixels), with 4000 elements, the computations needed are around 9x(1.2x10(exp 13)) floatingpoint 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 elementor, equivalently, the calculation of the roundtrip distance traveled by the acoustic pulse. This calculation requires, in a typical nearfield 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