CORRELATION OF ACOUSTIC SIGNALS SCATTERED AT A ROUGH SURFACE.
Abstract
The cross correlation and covariance of the acoustic signals reflected from a statistically-rough surface is given. The transition from small roughness to large roughness if given for a randomly corrugated surface. The sound reflected and scattered at each sub-area were separated into coherent and incoherent components. It was necessary to add the coherent components from the sub-areas coherently. The incoherent components were added incoherently. Numerical examples are given to show the magnitude of the signals scattered from the sub-areas. The covariance of signals observed at a pair of receivers are given as a function of the separation. The conditions of applicability of the theory to a geophysical problem have shown that: (1) The upper limit on the size of sub-areas is given by the lambda/8 criteria for the plane wave approximation. (2) The lower limit is given by the requirement that the dimensions of the sub-area be many correlation distances of the rough surface. (3) Far field conditions require that the source and receiver be many acoustic wave lengths from the surface. (Author)
Document Details
- Document Type
- Technical Report
- Publication Date
- Jul 01, 1969
- Accession Number
- AD0693115
Entities
People
- C. S. Clay
Organizations
- University of Wisconsin–Madison