| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide an ultrasonic flowmeter having a constitution for easily detecting the zero-cross point of receiving waveforms. Ž<P>SOLUTION: This ultrasonic flowmeter includes one set of transducers 21 and 22 for transmitting and receiving ultrasonic waves installed in the upstream and downstream of piping, and measures the flow rate of fluid based on the propagation time difference in bidirectional ultrasonic wave between the transducers 21 and 22. The ultrasonic flowmeter has a zero-cross detection section 29 for determining the zero-cross point of the receiving waveform of the transducers having received ultrasonic waves, and determines the propagation time difference based on the time difference of the zero cross point. The zero-cross detection section 29 determines the zero-cross point, by linearly interpolating between points showing values obtained by multiplying a peak value and minimum value, by a predetermined coefficient k, in the receiving waveform between the time of the peak value of the receiving waveform and the time of the minimum value, immediately in front of the peak value. Ž<P>COPYRIGHT: (C)2010,JPO&INPIT Ž
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