Frequency Based Noise Coherence-Function Extension and Application to Passive Bottom-Loss Estimation

Authors

Lanfranco Muzi, Portland State UniversityFollow
Martin Siderius, Portland State UniversityFollow
Peter L. Nielsen, Center for Maritime Research and ExperimentationFollow

Published In

The Journal of the Acoustical Society of America

Document Type

Article

Publication Date

9-2016

Subjects

Acoustics instrumentation, Spatial analysis, Underwater acoustics, Ocean floor -- Acoustic properties

Abstract

Accurate modeling of acoustic propagation in the ocean waveguide is important to SONAR-performance prediction. Particularly in shallow waters, a crucial contribution to the total transmission loss is the bottom refection loss, which can be estimated passively by beamforming the natural surface-noise acoustic field recorded by a vertical line array of hydrophones. However, the performance in this task of arrays below 2 m of length is problematic for frequencies below 10 kHz" role="presentation" style="display: inline; line-height: normal; word-spacing: normal; word-wrap: normal; white-space: nowrap; float: none; direction: ltr; max-width: none; max-height: none; min-width: 0px; min-height: 0px; border: 0px; padding: 0px 2px 0px 0px; margin: 0px; position: relative;">10 kHz10 kHz It is shown in this paper that, when the data are free of interference from sources other than wind and wave surface noise, data from a shorter array can be used to approximate the coherence function of a longer array. This improves the angular resolution of the estimated bottom loss, often making use of data at frequencies above the array design frequency. Application to simulated and experimental data shows that the technique, rigorously justified for a halfspace bottom, is effective also on more complex bottom types. Dispensing with active sources, small autonomous underwater vehicles equipped with short arrays can be envisioned as compact, efficient seabed-characterization systems. The proposed technique is shown to improve significantly the reflection-loss estimate of an array that would be a candidate for such application.

Description

This is the publisher's final pdf. Copyright (2016) Acoustical Society of America.

Version of record can be found at:

https://doi.org/10.1121/1.4962229

DOI

10.1121/1.4962229

Persistent Identifier

http://archives.pdx.edu/ds/psu/19446

Citation Details

Muzi, L., Siderius, M., & Nielsen, P. L. (2016). Frequency based noise coherence-function extension and application to passive bottom-loss estimation. The Journal of the Acoustical Society of America, 140(3), 1513-1524.