Numerical Filtering of Ultrasonic Backscattered Signals
Ultrasonic backscattered signals are caused by scattering of sound waves at the ensemble of polycrystals in various materials. Besides an overall exponential decay these curves exhibit a characteristic interference pattern which originates from incomplete phase cancellation of the scattered waves. The interference pattern severely limits the accuracy in determining the decay constant of the backscattered curve containing information on the mean grain size of the material under consideration. We describe a method which allows one to extract the attenuation constant despite this difficulty. It is based on the convolution of the backscattered signal with a gaussian of certain width D. D is closely related to the frequency components of the interference pattern, and can be derived experimentally.
KeywordsSurface Wave Interference Pattern Gaussian Filter Scattered Wave Backscatter Signal
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