Characterization of Diffusive Noise Fields Using Ambient Noise Interferometry, Spatial Gradients and Acoustic Bright Spots

Award Information
Agency:
Department of Defense
Branch
Navy
Amount:
$70,000.00
Award Year:
2010
Program:
STTR
Phase:
Phase I
Contract:
N68335-10-C-0432
Agency Tracking Number:
N10A-004-0723
Solicitation Year:
n/a
Solicitation Topic Code:
NAVY 10T004
Solicitation Number:
n/a
Small Business Information
Rocky Mountain Geophysics, Inc.
167 Piedra Loop, Los Alamos, NM, 87544
Hubzone Owned:
N
Minority Owned:
N
Woman Owned:
N
Duns:
826538360
Principal Investigator:
Steven Taylor
President
(505) 412-2841
srt-rmg@comcast.net
Business Contact:
Steven Taylor
President
(505) 412-2841
srt-rmg@comcast.net
Research Institution:
University of California, San Diego
Peter Gerstoft
Marine Physical Laboratory, Sc
University of California
San Diego, CA, 92093
(858) 534-7768
Nonprofit college or university
Abstract
We propose to conduct a feasibility study for utilizing broadband sampling of the diffusive noise field in a dynamic environment. In ambient noise studies, the ability to resolve a wavefield is proportional to its time-bandwidth (TB) product. In a dynamic environment such as in the atmosphere or ocean, the nature of the impinging wave field is changing rapidly so that only short time segments can be used to model the ambient wave field thereby reducing the TB product. One way to counter the effect of a reduced time window is to increase the bandwidth of measurement. Our approach is to broaden the frequency spectrum used to characterize diffusive noise fields in dynamic environments by addition of Intensity Level Differences (ILD) caused by diffraction around a shadowing object to the more commonly used interferometric phase delay methods. Diffraction around a shadowing object can create acoustic bright spots that are easily detected. As an experimental test, we will use ambient noise data from existing infrasonic arrays and characterize the dynamic wavefield using passive interferometry and spatial gradiometry techniques. For spatial gradient techniques, the required sensor footprint is smaller and the wavefield can be mapped at higher resolution at closer ranges.

* information listed above is at the time of submission.

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