This paper describes an algorithm of the crack reconstruction from noisy signals. In eddy current testing of steam generator tubes, signals are sometimes rendered noisy by the presence of other structures, such as support plates and tube sheets outside of test materials. Moreover, copper and magnetic deposits will also adhere outside the tube near the support plates and tube sheets. A round-robin test of SG tubes with noise source outsides is introduced by JSAEM. Experimental results of a transmit-receive type ECT probe are shown. Noisy signals are processed by a multi-frequency method but residual noise remains. Some other signal processing methods are discussed. Several artificial cracks are reconstructed and inverse results are shown in this paper.
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