| 摘要 |
Apparatus for the ultrasonic pulse-echo inspection of moving metal strip having a defect signal gate and a backwall signal gate adjusted to provide a backwall signal gate interval of fixed width and a fixed delay between the closing of the defect signal gate and the opening of the backwall signal gate is provided with means for automatically varying the time of closing the defect signal gate in response to changes in the relative position in time of the backwall signal with respect to the backwall signal gate interval so as to keep that gate interval in coincidence with the backwall signal. |
