Enhancement of signal noise ratio of eddy-current signals by wavelet transform

In eddy current testing of materials and structures, testing signals are unavoidably corrupted by measurement noises and other undesired signals, and signal processing techniques are usually needed to enhance the signal noise ratio for the defect detection and evaluation. In this paper, a noise reduction technique using wavelet transform is presented for the eddy-current signal processing. Noises in eddy-current signals are effectively reduced by decomposing the signals into wavelets components and then processing the wavelet coefficients. Furthermore, through the inverse wavelet transform of the processed wavelet coefficients, the eddy-current signals of high signal noise ratio are reconstructed.