Application of the reassignment time–frequency method on an acoustic signals backscattered by an air-filled circular cylindrical shell immersed in water

Authors: M. Laaboubi, E. Aassif, R. Latif, A. Dliou, G. Maze, D. Décultot

Abstract:
In this paper, the time–frequency representations of the Spectrogram (SP), the Reassigned Spectrogram (RSP), the Smoothed Pseudo-Wigner–Ville (SPWV) and the Wavelet Transform (WT) were used. These techniques are applied for analyzing experimental acoustic signal backscattered by an air-filled tube immersed in water. From the time–frequency images obtained, one can go up easily with certain characteristics of the acoustic waves such as the attenuation and the group delay of each circumferential wave. A comparative performance study of these four time–frequency representations was used. The reassigned spectrogram was chosen for its better localization and good resolution of the signal components in the time–frequency plane. It allows a better visibility of the circumferential waves which are propagated around the target. The estimated parameters from the reassigned spectrogram time– frequency image are in very good agreement with those obtained by the theoretical methods.

Keywords:
Acoustic signals
Spectral analysis
Time–frequency analysis
Reassigned spectrogram
Circumferential waves

Published in: Aerospace Science and Technology  (Volumes 27, Issue 1, June 2013)

Publisher: Elsevier

ISSN Information: 1270-9638

Application of the reassignment time–frequency method on an acoustic signals backscattered by an air-filled circular cylindrical shell immersed in water

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