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ARMA PROCESSING OF ULTRASONIC DATA FOR ABSORPTION MEASUREMENTS
- Source: Geophysical Prospecting, Volume 29, Issue 2, Mar 1981, p. 241 - 259
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- 27 Apr 2006
Abstract
Laboratory studies of absorption‐frequency behavior in rocks often use spectral ratios of digitally recorded ultrasonic signals which have been transmitted through a rock sample and a reference sample of very low absorption, respectively. It is proposed to treat the digitally recorded signals as an autoregressive‐moving average (ARMA) process which, using recursive filter concepts, can be represented as a ratio of two polynomials in the z‐transform variable z. The numerator polynomial contains only that part of the signal that is modified by anelastic effects, whereas the denominator contains the elastic effects of the physical apparatus such as reverberations. Examples are given which show that this separation of the recorded signal greatly facilitates the laboratory investigation of loss mechanisms and absorption‐frequency behavior based on spectral ratios.