| 摘要 |
PROBLEM TO BE SOLVED: To reduce power consumption in an ultrasonic flowmeter, to lower measurement error due to transient vibration in a transmitter-receiver when turning it on and to cancel out reverberant noise and 1.5 round-trip noise by turning on a power supply for an analog circuit of a received wave detection part only for a short period of time during reception. SOLUTION: A first transmission is performed by using a first transmission command signal from a control part. As soon as this is received, transmission is performed again, which is successively repeated a plurality of (n) times. When a zero crossing point of a specific order wave of received waves is caught, the measurement of total attainment time is started. After that, the power supply is turned on when a time period obtained by subtracting a fixed period of time from the previous attainment time has passed since this time transmission. After the total attainment time measurement is started, the first zero crossing is assumed to be a reception point after a fixed period of time has passed since the transmission based on the previous attainment time. In addition, the numbers of positive and negative drive pulses are equalized with each other. COPYRIGHT: (C)2004,JPO
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