| 摘要 |
PURPOSE:To obtain the titled measuring apparatus characterized in that installation work is simple, measuring time is short and performance and economical efficiency are excellent, by using a coaxial cable as a sensor and measuring the time from an incident pulse from a reflected pulse by integrating the reflected pulse to display the same. CONSTITUTION:A coaxial cable having waterproofness and stable characteristic impedance is used as a sensor. At first, a high-stability clock is formed by a quartz oscillation circuit 1 and a frequency dividing circuit 2 to be inputted to a pulse generating circuit 3 and a pulse having a constant width synchronous to a reference clock is formed and amplified by a power-amplifying circuit 4 to be applied to the coaxial cable from the terminal 9 thereof as an incidence pulse. The incidence pulse propagates through the coaxial cable to return as a reflected pulse. Only the reflected pulse not synchronous to the incidence pulse is detected by a reflected pulse detection circuit 5 and a (flip-flop) FF circuit 6 leads out high level output when is set by the output of the circuit 2 and is reset by the output of the circuit 5 to obtain low level output. The output of an integrating circuit 7 receiving the output of the circuit 6 is given by a predetermined formula and proportional to the length of the coaxial cable and, therefore, if the output voltage of the circuit 7 is measured, the length of the coaxial cable is determined.
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