Enhanced target detection and classification using two-pulse sonar methods

Mistry, Nikhil, White, Paul and Leighton, Timothy (2016) Enhanced target detection and classification using two-pulse sonar methods. Journal of the Acoustical Society of America, 140 (4), 2968. (doi:10.1121/1.4969181).

Abstract

A number of two-pulse sonar techniques can be employed to separate linear and nonlinear scatterers. Twin Inverted Pulse Sonar (TWIPS) and Biased Pulse Summation Sonar (BiaPSS) are processes that exploit nonlinear bubble dynamics to perform such a classification, with clutter reduction. Consequently, these techniques can be used to enhance target detection in bubbly waters. TWIPS and BiaPSS rely upon bubbles being driven to large nonlinear pulsations, but this is dependent upon availability of a high-amplitude source. Previous studies could only access a narrow-band source and therefore used a low frequency so that, over the rarefaction cycle, most ocean bubbles would expand sufficiently (the size range of near-surface ocean bubbles under waves and wakes being large). However, recent access to a broadband high-power source has allowed exploitation of bubble resonances. This talk presents results of investigations using broadband linear sine sweeps, of which one is based upon the simulation of an Atlantic Bottlenose Dolphin (Tursiops truncatus) echolocation click from Capus et al. (2006). Insonifying a cloud of bubbles with a wide band of frequencies excites as many of those sizes at, or close to, their resonance. As such, the contrast between linear and nonlinear scatter is enhanced, improving the target detection capability.

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Contributors

Author: Nikhil Mistry

Author: Paul White

Author: Timothy Leighton

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