| 摘要 |
There is disclosed a liquid velocity measuring apparatus comprising an actuable generator for providing a relatively high frequency signal to a transmitting transducer for directing an ultrasonic wave into a conduit through which liquid is directed. A receiver transducer is disposed to receive the acoustical wave as reflected from the liquid, and to provide an output signal to be amplified and demodulated to provide a train of high frequency pulses, the frequency of which is indicative of the velocity of the liquid directed through the conduit. The train of pulses is applied to a counter and a decoder for respectively counting and decoding the pulses to provide a signal to a display whereby a digital indication of the liquid velocity is given. Further, a timing circuit is provided for enabling the generator, the counter and the decoder for a first, relatively short period of time, made dependent upon the cross-sectional area (or diameter) of the conduit through which the liquid is directed, and for energizing the display for a second, relatively long period of time to permit reading of the display.
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