| 摘要 |
PROBLEM TO BE SOLVED: To solve the problem, wherein a difference arises in a received waveform between the upstream side and the downstream side, in a portion where a reception amplitude is relatively large and the difference is detected as error in the propagation time of ultrasonic waves, at the determination of the propagation time. SOLUTION: In this device for measuring flow velocity or a flow rate, a received signal is amplified by a receiving means 35, and a receiving point storage means 38 updates the signal, by overwriting until the maximum value of the signal comes between VH and VL and stores updated receiving point data. Since updating by overwriting i stopped, when the value becomes between VH and VL, a zero crossing point before the maximum amplitude point of a received wave can be made a receiving point, it is possible to measure the propagation time with a reduced error and to attain a power-saving operation by shortening of measurement time. COPYRIGHT: (C)2011,JPO&INPIT |
