Accession Number:

ADA426191

Title:

Vertical Directionality of Low-Frequency Wind Noise and Vertical Array Optimization for the Wind Noise Limit

Descriptive Note:

Formal rept. 1 Oct 2001-30 Sep 2002

Corporate Author:

NAVAL RESEARCH LAB WASHINGTON DC

Report Date:

2004-08-27

Pagination or Media Count:

21.0

Abstract:

Normal mode-based noise modeling is applied to investigate the structure and the environment dependence of vertical wind noise directionality and the optimal design of vertical arrays for detection in a wind noise background, using, as examples, two deep-water sites, one in the North Atlantic and the other in the North Pacific. The contributions to the noise directionality of the overhead direct-path, surface-interacting, and sediment-interacting components of the noise field are examined through analysis of the vertical noise response of a reference aperture. Environmental influences investigated include the effects of 1 the wind noise source distribution in range, and 2 the acoustic propagation environment, including water-column depth and sound speed, sediment attenuation, and sea surface roughness. Spatial configurations of vertical arrays with arbitrary phone spacing are optimized by simulated annealing to maximize a measure of the mean array The beam patterns of the optimized arrays adapt to the noise directionality by trading off beamwidth, sidelobe levels, and single-element signal-to-noise ratio.

Subject Categories:

  • Acoustic Detection and Detectors
  • Acoustics

Distribution Statement:

APPROVED FOR PUBLIC RELEASE