| 摘要 |
Method and apparatus for determining a speed of a flow of a liquid or a gas in a pipe by measuring the travel time of ultrasonic pulses. A received ultrasonic pulse is digitized and transformed to a complex digital signal by a Hilbert filter. From the phase history and the amplitude history of the pulse, and from ultrasonic pulses that were received previously, the speed of the flow is determined. <IMAGE>
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