Underwater Acoustic Imaging: Rapid Signal Processing
Abstract
An innovation program to develop an underwater acoustic imaging system able to resolve objects down to millimetre resolution in turbid waters is under way. The defence need is for the identification of minelike objects. This report reviews options for the signal processing or beamforming stage of the program. An image consisting of 3x10 to the 9th power voxels (volume pixels) could be formed by a summation of the voltages from 4000 sensor elements, each taken from the element's voltage stream at the appropriate time. With a suitable allowance (factor of 9) for calculating the time delays, it appears at first sight that 9x1.2x10 to the 13th power operations would be required. The problem is to calculate a three-dimensional image of adequate quality in the shortest time at the least cost. A hierarchical structure of options is developed in an attempt to capture all possibilities. At the top level, three approaches are identified. First, the use of appropriate hardware, such as computers with parallelism. Second, a reduction in the number of operations (a software' solution). And third, the defining of a suitable reduced goal, which appears to come down to the imaging of a subvolume of the original volume that contains the object of interest. Each of these three approaches is divided into suboptions; these are discussed in detail to bring out difficulties and advantages.
Document Details
- Document Type
- Technical Report
- Publication Date
- Apr 01, 1998
- Accession Number
- ADA349020
Entities
People
- David G. Blair
- Ian S. Jones
Organizations
- Defence Science and Technology Group