| 摘要 |
PROBLEM TO BE SOLVED: To provide an ultrasonic flowmeter causing no synchronous deviation of detection timing to prevent a flow speed/rate measurement error due to a detection timing error. SOLUTION: This ultrasonic flowmeter is provided with a timing means 4 deciding at least one sampling selection window synchronously with an ultrasonic transmission signal, a signal receiving means 5 receiving an ultrasonic wave transmitted in the normal/opposite direction during the sampling selection time window, a received signal waveform shaping means 6 correlating the received signal and a filtering pattern with each other, a synchronism detection means 7 detecting a trigger level as a synchronism detection point from the shaped signal waveform, a propagation time difference computing means 8 computing a propagation time difference of an ultrasonic wave propagated in the normal/opposite direction from the detected synchronism detection point, and a flow rate computing means 9 finding a flow speed/rate of the fluid on the basis of the propagation time difference.
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