On the time-frequency analysis of signals that decay exponentially with time

The use of the short-time Fourier transform and the wavelet transform imple mented using the new harmonic wavelets for analyzing the time variation of the spectral contents of exponentially time-decaying signals is studied in the present investigation. Focus is also placed on how well these methods c an recover the decay constant of each frequency component in the signals in a relatively narrow bandwidth situation. Both artificial and experimentall y recorded signals have been used. Results suggest that the short-time Four ier transform is in general more reliable than the wavelet transform for th e present purpose. The short-time Fourier transform also gives excellent re covery of the decay constants if the signals are made up of discrete freque ncy components. (C) 2000 Academic Press.