| 摘要 |
PROBLEM TO BE SOLVED: To improve measurement accuracy by eliminating the biasing of a measurement error. SOLUTION: An ultrasonic flowmeter is provided with a transmitter 1 for transmitting an ultrasonic signal, a drive circuit 9 for driving the transmitter 1, a receiver 2 for receiving an ultrasonic signal that is transmitted from the transmitter 1 and is propagated through fluid, a reception detection circuit 10 for receiving the output of the receiver 2 and detecting the ultrasonic signal, a timer 11 for measuring the propagation time of the ultrasonic signal, an operation part 12 for obtaining a flow rate from the output of the timer 11 by an operation, and a drive frequency modification part 13 for modifying the drive frequency of the drive circuit 9. As a result, the drive frequency modification part changes the drive frequency of the transmitter with time for transmission, thus preventing influence being given to a reception signal by reverberation and reflection waves for dispersing and averaging and hence eliminating the biasing of a measurement error.
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