| 摘要 |
PURPOSE:To measure the distance between two points without utilizing any reflected wave by finding the distance between the two points according to the difference in time required for transmission between two kinds of signals which differ in transmission speed. CONSTITUTION:A transmitter 1 is equipped with a radio wave transmission part 1a which sends a radio wave and an acoustic wave transmission part 1b which sends an ultrasonic wave, and radiates the radio wave and ultrasonic waves at the same time. A receiver 2 inputs the outputs of a radio wave receiving circuit 5 and an acoustic wave receiving circuit 6 to a time difference detecting circuit 7, generates a start signal when the output level of the circuit 5 becomes L, and generates a stop signal when the output level of the circuit 6 becomes L. Here, the radio wave has a speed about 10<6> times as fast as that of the ultrasonic wave, so the time from the stop of the radio wave to the detection on the side of the receiver 2 is found on the side of the transmitter 1 and the distance between the transmitter and receiver 2 is found by considering the propagation speed of the ultrasonic speed.
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