Le Gonidec Y, Conil F, Gibert D
Géosciences Rennes (CNRS UMR 6118), Campus de Beaulieu, Université Rennes 1, 35042 Cedex, Rennes, France.
Ultrasonics. 2003 Aug;41(6):487-97. doi: 10.1016/s0041-624x(03)00151-3.
We analyze interfaces by using reflected waves in the framework of the wavelet transform. First, we introduce the wavelet transform as an efficient method to detect and characterize a discontinuity in the acoustical impedance profile of a material. Synthetic examples are shown for both an isolated reflector and multiscale clusters of nearby defects. In the second part of the paper we present the wavelet response method as a natural extension of the wavelet transform when the velocity profile to be analyzed can only be remotely probed by propagating wavelets through the medium (instead of being directly convolved as in the wavelet transform). The wavelet response is constituted by the reflections of the incident wavelets on the discontinuities and we show that both transforms are equivalent when multiple scattering is neglected. We end this paper by experimentally applying the wavelet response in an acoustic tank to characterize planar reflectors with finite thicknesses.
我们在小波变换框架下利用反射波分析界面。首先，我们引入小波变换，它是一种检测和表征材料声阻抗剖面中不连续性的有效方法。文中给出了孤立反射体和附近缺陷多尺度簇的合成示例。在本文的第二部分，当待分析的速度剖面只能通过传播小波穿过介质进行远程探测时（而不是像小波变换那样直接卷积），我们将小波响应方法作为小波变换的自然扩展提出。小波响应由入射小波在不连续处的反射构成，并且我们表明当忽略多次散射时，这两种变换是等效的。本文最后通过在声学水槽中实验应用小波响应来表征具有有限厚度的平面反射体。
