METHOD FOR REDUCING DIGITAL DATA IN AN EMAT PIG

摘要

To determine the size of defect, an envelope is formed determining the width of an ultrasonic sleeve and the minima between peak amplitudes falling below a threshold. The time between the minima is stored. If the peak amplitude between two vectors does not exceed the threshold the minimum amplitude peak is determined. Envelopes with a width less than the threshold or with a form not having desired characteristic are excluded. Amplitude and propagation time are determined for the envelopes and the data is compressed. To determine the signal base, the ultrasonic echoes are divided into time intervals of length four times the ultrasonic frequency wavelength. The peak amplitudes in these times are averaged.