Method of measuring the delay of ultrasound in the pulse reflection method

摘要

PCT No. PCT/DE91/00964 Sec. 371 Date Sep. 30, 1992 Sec. 102(e) Date Sep. 30, 1992 PCT Filed Dec. 12, 1991 PCT Pub. No. WO92/10746 PCT Pub. Date Jun. 25, 1992.A delay time measurement method for ultrasound of the type wherein a testing head transmits an excitation pulse that is as close as possible to the shape of a shock wave and traverses a pretravel path until it reaches the object to be examined which has a front wall and a rear wall, with at least one reflected pulse being generated at its front wall as well as at its rear wall. To improve the above-mentioned type method so that delay time measurements for thickness determinations and abnormalities can be performed reliably even on rough surfaces and if reflected pulses are missing or falsified, a time window is determined for the recording of reflected pulses that follow the excitation pulse, within which window all successive reflected pulses are digitized. Then the reflected pulses that lie within the time window are digitally filtered and parametrized, and the filtered and parametrized reflected pulses are fed to a computer unit and are evaluated on the basis of variable criteria using a predetermined algorithm.