Time, Wavelet and Hilbert-Huang Domain Analysis of Signals from Ultrasonic Based Equipment for the Non Destructive Evaluation of Concrete and Brick Masonry Walls

In this paper we compare the effectiveness of the time, wavelet and Hilbert-Huang domain analysis of waveforms from a Non Destructive Test (NDT) equipment. The analysis of the signals from NDT systems is one of the most important activities in the recognition of the presence of possible defects that are usually associated with the presence of echoes from the defects themselves. Very often the echoes traveling back to the sensors are superimposed with the signal from the transducer. We analyze the waveforms obtained by couples of sensors in order to extract the echoes and to recognize the points were they originate. Data are obtained by a measurement campaign on a concrete wall and on masonry specimens of different texture and thickness.