| 摘要 |
The level measuring system measures a variable level within a sensing area containing a mass of material. A sensing probe is positioned within the area and is coupled to the tank of an oscillating circuit through a switching network. A reference probe positioned in or near the sensing area is also coupled through the switching network to the tank of the oscillating circuit. The frequency of oscillation will depend upon a physical parameter of the mass of material within the immediate vicinity of sensing probe. Environmental conditions affecting the reactance of the sensing probe will equally affect the reference probe and therefore a change in the frequency produced by the sensing probe relative to the frequency produced by the reference probe will provide a true indication of the physical parameter being measured. Signal processing means are coupled to the oscillator for processing this frequency change. The sensing probe can be a cable antenna extending vertically into a material container for measuring the level of the material therein.
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