The driving of traditional eddy current instrument is sine wave, processing of signal is also main frequency, so many useful information which within subaltern wave are neglected EEC-41 eddy current instrument adopts Fourier transformation method to analyze the signal in real time, calculate and restore the main frequency and high times harmonic weight of the signal, effectively measure and analyze defect or physics and chemistry performance of work pieces Therefore the EEC-41 can be used in the occasion of general eddy current, low frequency eddy current, pulse eddy current, remote field and leaking magnetism This instrument can choose, analyze the main frequency of the signal or 2,3,4,5,6,7 times harmonic weight, have broken the limitation of the general eddy current instrument that only inspect the main frequency of signal So it greatly expands the range of application, and the function take on an entirely new look