| 摘要 |
PURPOSE:To enable a distance to be accurately measured by providing a child instrument with receiving means for receiving ultrasonic pulses from a parent instrument, stand-by time setting means, transmitting means for transmitting the ultrasonic pulses to the parent instrument after the elapse of the stand-by time end the like. CONSTITUTION:A parent instrument 4 intermittently drives a ultrasonic oscillator 2T with a wave transmitting circuit 10 to form ultrasonic pulse waves. By the signals to which ultrasonic signals received by the oscillator 2T are amplified (11) and detected (12) and a DELTAT gate formed from the circuit 10 by a DELTAT gate forming circuit 13, the parent instrument 4 outputs signal discriminating signals and distance signals from a signal discriminating circuit 14 and displays (15) a distance. A child instrument 5 amplifies (16) and detects (17) ultrasonic pulse waves received by a ultrasonic oscillator 2R and, when the received waves are judged to be signals transmitted from the parent instrument 4 by a signal discriminating circuit 24, opens a transmitting gate 19 after a time DELTAT has elapsed from reception by a DELTAT delay circuit 18, driving the oscillator 2R from an oscillating circuit 20 and a wave transmitting amplifier 21 to transmit ultrasonic pulse signals. The time DELTAT is set to a time required for the reflected waves of the ultrasonic pulse waves to disappear.
|
