In:
The Journal of the Acoustical Society of America, Acoustical Society of America (ASA), Vol. 122, No. 5_Supplement ( 2007-11-01), p. 2960-2960
Abstract:
Optical fiber infrasound sensors (OFIS) are compliant tubes wrapped with two optical fibers that integrate pressure variation along the length of the tube with laser interferometry. The coherent signals traveling at acoustic speed are averaged along the length of the OFIS at the speed of light, while spatially incoherent noise traveling at wind speed is attenuated. We present new wind noise measurements, which augment initial work that suggested an OFIS has a lower noise floor above 1 Hz than a traditional microbarometer with a rosette pipe or hose filter in light wind. We also discuss OFIS configurations and techniques to determine the signal phase velocity direction. The instrument response is a function of the orientation of the OFIS relative to that of the wavefront. That property can be exploited to help determine the phase velocity of infrasound signals. This type of instrument-response-dependent beamforming is theoretically an improvement to standard beamforming for the same number of sensors when the signals are immersive or continuous in nature. When the signals are more impulsive in nature, the success of these techniques mostly depends on how successful the OFIS is in reducing wind noise and the signal bandwidth.
Type of Medium:
Online Resource
ISSN:
0001-4966
,
1520-8524
Language:
English
Publisher:
Acoustical Society of America (ASA)
Publication Date:
2007
detail.hit.zdb_id:
1461063-2
