The de-noising of sonic echo test data through wavelet transform reconstruction

This paper presents the results of feasibility study into the application o f the wavelet transform signal processing method to sonic based non-destruc tive testing techniques. Finite element generated data from cast in situ fo undation piles were collated and processed using both continuous and discre te wavelet transform techniques. Results were compared with conventional Fo urier based methods. The discrete Daubechies wavelets and the continuous Me xican hat wavelet were used and their relative merits investigated. It was found that both the continuous Mexican hat and discrete Daubechies D8 wavel ets were significantly better at locating the pile toe compared than the Fo urier filtered case. The wavelet transform method was then applied to field test data and found to be successful in facilitating the detection of the pile toe.