A new method for quasi on-line eddy current signal analysis : wavelet transform

In this paper, a new method for the automatic analysis of eddy current impedance signals from the testing of tubes with differential probes is proposed. This method is based on the wavelet transform, the application being prompted by the fact that the quadrature components of the signals from the individual indications can be modelled by a function which satisfies the condition to be a wavelet. Initial laboratory work was carried out on standard tubes with graded defects. The method was then checked on tubes with real defects from a laboratory mock-up condenser.