ASA 128th Meeting - Austin, Texas - 1994 Nov 28 .. Dec 02

5aSA10. Wave packet synthesis via the wavelet transform.

David M. Drumheller

David H. Hughes

Brian O'Connor

Charles F. Gaumond

Acoust. Div. Naval Res. Lab., Washington, DC 20375-5350

A wavelet transform is used to synthesize distinct contributions from the monostatic form function for a randomly ribbed, complex end-capped, finite cylindrical shell. In order to achieve satisfactory wave packets, as measured by their cross-correlation with the original impulse response, two wavelet transforms are used, a temporal wavelet transform and a spectral wavelet transform. This is in contrast to synthesizing wave packets from the Wigner distribution where just one two-dimensional surface was necessary. However, interference terms between components in the Wigner distribution, which is quadratic in the underlying signal, are absent in the linear wavelet transform. This allows for a more facile synthesis of the acoustic excitations. The interference terms in the Wigner distribution can sometimes fall at points in the time-frequency plane where a signal component exists, making it difficult to synthesize that component without corruption caused by the presence of other compounds in the form function.