| 摘要 |
PURPOSE:To make it possible to accurately detect the length of a sensor cable, by sampling the reflection signal from the leading end of the sensor cable in a real time to convert the same to an image signal and calculating the peak position or rising position (time) of the reflection signal. CONSTITUTION:An electric pulse is generated from a pulse generator 14 by the order of a control operation apparatus 18 to be incident to a sensor cable 10 and a reference cable 12 through a switch circuit 16. One shots of the reflected pulses from the leading ends of the cables 10, 12 are detected by a real time sampling type oscilloscope 20 to be displayed on CRT of said oscilloscope 20. The wave forms thereof are caught as images by an image sensor 22 to be digitally stored in an image memory apparatus 24. If the peak positions and rising positions of the wave forms are found out numerically by the apparatus 18, a reflection position (time) can be calculated and, if said position is multiplied by the propagation speed of the pulse, the length of the cable 10 can be measured. As mentioned above, by alternately measuring the cables 10, 12 to compare the measured values, the change in the length of the cable 10 is automatically and accurately calculated by the apparatus 18 and the calculated result is displayed on a display device 26.
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