Analog computation of wavelet transform coefficients in real-time

The authors present a time-domain approach for the implementation and continuous generation of wavelet transform coefficients for spectral analysis applications. The wavelet generation relies on amplitude modulation techniques. This approach offers two extra degrees of freedom through the appropriate use of the modulation index and the selected envelope signal. The added flexibility along with choice of frequencies allows one to generate different time-frequency windows with equal resolution for all frequencies. A convolution (correlator) circuit that computes the wavelet transform and delivers the coefficient corresponding to each wavelet was designed to substantiate theoretical findings. Experimental results of a hardware prototype are presented.