Spectral-temporal filtering of NDT data using wavelet transform modulus maxima

In this paper, a method is described for the filtering of non-destructive testing (NDT) signals. By employing wavelet transform modulus maxima filtering in the time–frequency plane, it allows the high frequency components associated with features within the signal to be retained while high frequency components associated with both signal ring down and noise are removed. The method is applied to sonic echo signals associated with the NDT of piled foundations. The method allows for spectral-temporal filtering of the signal and offers a superior partitioning of the signal of interest from both noise and ringdown artefact. The method has applications in the elucidation of other signals.