| 摘要 |
PROBLEM TO BE SOLVED: To accurately detect quantities of flow etc. by accurately measuring propagation delay times independently of anomalies of transducers such as the adhesion of foreign matter to diaphragms in an ultrasonic fluid measuring apparatus. SOLUTION: The actual frequency (fr) of received waves Wr is detected to reflect the detected frequency (fr) of the received waves in the measurement of a propagation delay time (t). In the case of computing a propagation delay time (t) by subtracting a prescribed detection delay time (tr) from an elapsed time (td) from the transmission time point (t0) of ultrasonic waves to a zero-cross point, the prescribed detection delay time (tr) is corrected on the basis of the frequency (fr) of the received waves. When the frequency (fr) of the received waves is lower, it is preferable to correct the detection delay time (tr) by increasing it more (tr'=tr+δt). COPYRIGHT: (C)2006,JPO&NCIPI
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