Measurement and analysis of array gain degradation due to bubble scattering

Park, J. Daniel, Holt, Fred D., Culver, R. Lee, Coles, David and Leighton, Timothy (2010) Measurement and analysis of array gain degradation due to bubble scattering. Journal of the Acoustical Society of America, 127 (3), part 2, 1817-1818. (doi:10.1121/1.3384194).

Abstract

When an array is steered in the direction of a signal, array gain (AG) is maximum when the signal is coherent across the array, meaning that the signals add in phase for all elements and the noise or interference is incoherent across the array (i.e., it adds with random phase). For an acoustic array operating in the ocean, we would like to understand the degree to which scattering by nearby bubbles degrades AG. Bubble attenuation can also degrade array performance by attenuating the signal of interest, but that is separate from AG degradation. The degradation of AG due to scattering by nearby bubbles has been measured for different bubble densities. We have analyzed the relationship between bubble density at the array and the degradation in AG. We present probability density functions (pdfs) of signal amplitude and phase at the array elements. The amplitude pdfs can be approximated as a Rayleigh–Rice distribution, and the phase pdfs follow the von Mises distribution. With independence assumed between amplitude and phase distributions, simulated distributions generate array gain distributions closely matching the measured AG distribution

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Contributors

Author: Timothy Leighton

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