| 摘要 |
PURPOSE:To measure a wide range of distance, by correcting the propagation loss of an ultrasonic signal and adding peak AGC function. CONSTITUTION:An ultrasonic wave is transmitted from a transmission part 3 driven by a pulse wave synchronous to the fundamental timing of a main oscillation part and the ultrasonic wave reflected by a reflecting article 11 is received by a receiving part 4. The received ultrasonic signal is amplified by a signal amplifier 5 and the distance up to the reflecting article 11 is operated and displayed from the amplified signal. The peak value of the output waveform of the amplifier 5 is detected by a peak detector 6 and an amplifier control circuit 7 allows the amplifying degree of the amplifier 5 to increase in synchronous relation to the main oscillation part 1 over time and performs control so as to keep the max. value of the output voltage of the amplifier 5 constant on the basis of the output of the peak detector 6.
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