| 摘要 |
PURPOSE:To calibrate phase characteristics easily and surely by supplying the frequency differing from the frequency supplied to a flaw detecting probe by means of electromagnetic coupling. CONSTITUTION:A flaw detecting probe 2 is connected to an eddy current flaw detector 1 to be tested, and a high frequency signal 7' is supplied to the probe 2. The detector 1 inputs the signal to a cathode-ray tube 3 for two-dimentional display. Now when the probe 2 is inserted into a hollow bobbin 8, the frequencies of the sum and the difference of the frequencies f1, f2 of the high frequency signals 7, 7' are obtained with respect to said frequencies by the electromagnetic coupling with the magnetic field generated by a coil 9. Then if the phase characteristics of a processing circuit are linear with respect to the input phase, a true cicle is drawn on the tube 3 and from the condition of the circle, the phase characteristics are known. Thus the phase characteristics are calibrated easily and accurately. |
