Wavelet Screenshot

AGU-Vallen Wavelet is a tool which allows you to calculate and display the wavelet- and Choi-Williams distribution of individual waveforms. A time-frequency transform distributes the energy of a wave in time and frequency. Hence it is possible to identify at what time which frequency content occurs. This kind of analysis is not possible by use of standard Fourier transform.

AGU-Vallen Wavelet has been developed in collaboration between Vallen Systeme GmbH, Aoyama Gakuin University (AGU), Tokyo, Japan and University of Denver, US. The AGU group has pioneered in the research of time-frequency analysis in the field of Acoustic Emission and Vallen has actively generated software tools.

Choi-Williams distribution was added in 2009 to AGU-Vallen Wavelet program.

About wavelet transformation

A wavelet transform (WT) of an AE signal provides information which wave modes carry significant energy and where in a mode the energy as a function of frequency and time is to be found.

About Choi-Williams transformation

The time-frequency transformation called Choi-Williams transform as proposed by Hyung-Ill Choi and William J. Williams and first published in IEEE Transactions on Acoustic Speech and Signal Processing Vol. 37, No. 6, June 1989. The advantage of the Choi-Williams transformation is the improved resolution of frequency vs. time. A minor drawback is the less sensitive energy resolution.

AGU-Vallen Wavelet is freeware. Download it free of cost in our downloads section. Directly access the file from here: AGU-Vallen Wavelet (wvsetup.exe, ca. 3.3MB)