| 摘要 |
PROBLEM TO BE SOLVED: To detect accurately a propagation time difference of an ultrasonic wave by a simple operation. SOLUTION: An ultrasonic signal emitted from an ultrasonic vibrator 2 on the upstream of a conduit 1 is received by a vibrator 3 on the downstream, and an ultrasonic signal emitted from the vibrator 3 on the downstream is received by the vibrator 2 on the upstream, and two digital data acquired by sampling each signal are determined. In an operation unit 9, while shifting each time base of the data, the sum total of differences of two signal strings is determined, and the propagation time difference is determined in a CPU 11, based on a point where the sum total of differences becomes minimum, to thereby determine the flow velocity of fluid. COPYRIGHT: (C)2008,JPO&INPIT
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