| 摘要 |
A system for the automatic measurement of the level, flow rate, and flow volume of liquid flowing through a channel is described. An echolocation system operates to detect returns from the surface of the liquid in the channel during successive transmission cycles in response to the reflection of sonic signals. A source of pulses having a frequency which provides a certain number of pulses corresponding to the travel time of the sonic signals over a distance equal to a maximum predetermined level or head of the liquid in the channel provides pulses from which the liquid level, flow rate, and flow volume can be obtained. The control of the frequency of the pulses from which the measurements are obtained may be accomplished by a digital phase locked loop system to minimize the effects of changes in ambient condition, such as temperature, vapor pressure, and composition of atmosphere as often occurs in such conduits. The system may therefore be used for monitoring liquid levels in a container, effluents, such as waste water in a sewage system and controlling the sampling of such waste water each time a preset volume thereof is discharged via the conduit. Also solids levels in a container may be measured as may any distance from the transducer according to its preset range.
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