| 摘要 |
PURPOSE:To prevent erroneous operation due to the effect of secondary reflection and to reduce power, by variably controlling the level of an ultrasonic pulse transmitted in inverse proportion to the receiving level of a reflected ultrasonic pulse. CONSTITUTION:A signal processing part 1 uses a DC power source +V as a power source to generate a transmission order signal A at a predetermined constant cycle. A transmission part 2 receives the supply of the signal A from the processing part 1 to transmit an ultrasonic pulse B and a receiving part 3 receives the reflected wave B' from an object 4 to be measured of the pulse B to output a receiving signal C to supply the same to the processing part 1. A peak holding part 5 receives the signal C from the receiving part 3 and holds the peak level thereof until the next signal C is supplied to output the same. A transmission level control part 6 supplies the output obtained by applying level control to the power source +V in inverse proportion to the output signal of the peak holding part 5 to the transmission part 2 to variably control the level of the ultrasonic pulse transmitted by the transmission part 2.
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