The purpose of this paper is to experimentally demonstrate advantages of a
multi-frequency ECT system. In this system, a precise crack imaging was ach
ieved by using spectrograms obtained from an eddy-current probe multifreque
ncy response. A complex signal containing selected sinusoidal components wa
s used as an excitation, The results of measurements for various test speci
mens are presented. (C) 2000 Elsevier Science B.V. All rights reserved.