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Proceedings Paper

Applications of higher-order spectral analyses to detection and identification of seismic and acoustic signals generated by machinery
Author(s): Zoltan A. Der; Douglas R. Baumgardt
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Paper Abstract

Machinery typically generates mechanical vibrations at multiple, harmonically related frequencies which arise from various mechanically coupled moving components of machines or characteristic nonlinearities in their operational loads. These mechanical vibrations propagate from their origin through the air as acoustic waves and through the earth as various types of seismic waves. Of the two modes of propagation the seismic mode of propagation is the more complicated since the same harmonic may propagate simultaneously in various wave types (compressional waves, shear waves and various surface wave types) with differing propagation vehicles. Moreover, air-to-ground coupling has been shown to occur in some cases. The consequence of this multi-mode propagation is that standing wave interference patterns are set up over the terrain surrounding the sources which complicates the frequency-wavenumber analysis and identification of the signals. Since the set of harmonics omitted from a given type of machinery tend to be phase- coupled, higher order spectral analysis offers means for detecting and separating such coupled sets and reducing much of the Gaussian background noise and uncoupled sinusoidal noise components. In this paper we utilize sections through bispectral estimates obtained from continuous signals from various types of machinery with durations exceeding a minute.

Paper Details

Date Published: 24 July 1997
PDF: 11 pages
Proc. SPIE 3081, Peace and Wartime Applications and Technical Issues for Unattended Ground Sensors, (24 July 1997); doi: 10.1117/12.280643
Show Author Affiliations
Zoltan A. Der, ENSCO, Inc. (United States)
Douglas R. Baumgardt, ENSCO, Inc. (United States)

Published in SPIE Proceedings Vol. 3081:
Peace and Wartime Applications and Technical Issues for Unattended Ground Sensors
Gerold Yonas, Editor(s)

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