Time-Exposure Acoustics for Imaging Underground Structures
Abstract
We have developed a new technique for imaging underground facilities based on the passive monitoring of acoustic emissions from both stationary and moving equipment within such facilities. It is well known that all mechanical devices, such as motors, gears, etc, emit acoustic signals. It is possible to identify an acoustic source based on its noise spectrum. Passive "listening" has been considered and employed in the past to detect underground structures based upon noise emitted from within. The fundamental difference in our approach is that we rigorously considered the inverse source problem subject only to the assumption that the noise source is localized. Rather than using time delays across a sensor array to "triangulate" on the source, our method, known as time-exposure acoustics (TEA), coherently sums the data receiver over an array of sensors and back-propagates it into the host geologic formation. This procedure yields an image of the source that is similar to the image formation process used in reflection seismic exploration.
Document Details
- Document Type
- Technical Report
- Publication Date
- Sep 30, 2003
- Accession Number
- ADA417769
Entities
People
- Alan Witten
- Alex Oren
- Frank Funak
- I. J. Won
- Steve Norton