Abstract: Wavelet transform processing is performed on an input signal received at a receiver circuit of an electronic article surveillance (EAS) system. The input signal includes a target signal generated by an EAS marker and also includes correlated high amplitude interference signals. The wavelet transform processing is performed so as to generate from the input signal plural wavelet transform signals having mutually different phases. The wavelet transform is substantially phase invariant with respect to the interference signals and lacks phase invariance with respect to the target signal. Uncorrelated components of the plural phase-diverse wavelet transform signals are identified to detect the target signal.

Abstract: The present invention is generally directed to an apparatus and method of echo identification wherein the sources of echoes generated from interface boundaries in a medium may be more effectively identified in the processing of obtained waveform data to generate higher resolution in the obtained data. The method of the present invention is particularly useful for performing ultrasound reflectometry and medical sonography by obtaining data representative of a medium being studied and suppressing signals from overlapping echo waveforms generated from obstacles adjacent an object under test. More particularly, the method of the invention enables the sources of such echo waveforms to be more effectively identified to yield an indication of the contribution of overlapping echoes to generate higher resolution data signals. The processing includes generating a power spectral estimate of the data which is utilized to obtain a phase estimate thereof.