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Ultrasonic correlator versus signal averager as a signal to noise enhancement instrumentUltrasonic inspection of thick and attenuating materials is hampered by the reduced amplitudes of the propagated waves to a degree that the noise is too high to enable meaningful interpretation of the data. In order to overcome the low Signal to Noise (S/N) ratio, a correlation technique has been developed. In this method, a continuous pseudo-random pattern generated digitally is transmitted and detected by piezoelectric transducers. A correlation is performed in the instrument between the received signal and a variable delayed image of the transmitted one. The result is shown to be proportional to the impulse response of the investigated material, analogous to a signal received from a pulsed system, with an improved S/N ratio. The degree of S/N enhancement depends on the sweep rate. This paper describes the correlator, and compares it to the method of enhancing S/N ratio by averaging the signals. The similarities and differences between the two are highlighted and the potential advantage of the correlator system is explained.
Document ID
19910035042
Document Type
Conference Paper
Authors
Kishoni, Doron (NASA Langley Research Center; College of William and Mary Hampton, VA, United States)
Pietsch, Benjamin E. (Industrial Quality, Inc. Gaithersburg, MD, United States)
Date Acquired
August 15, 2013
Publication Date
January 1, 1989
Subject Category
INSTRUMENTATION AND PHOTOGRAPHY
Meeting Information
International Instrumentation Symposium(Orlando, FL)
Distribution Limits
Public
Copyright
Other