| 摘要 |
An acoustic flow meter in which a plurality of different frequencies are transmitted in both upstream and downstream directions, and corresponding differences in transmission phase-delays due to such frequency changes detected and used to compute the fluid velocity by the formula <IMAGE> when L is the distance between transmitter and receiver, MD is the slope of the graph of phase delay vs. transmitted frequency for the upstream direction of transmission, and Mu is the corresponding slope for the downstream direction. A signal processor using a least-squares algorithm is preferably employed to obtain best values for MD and Mu from the several values of phase-delay difference produced by the several different transmitted frequencies.
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