| 摘要 |
A system for indicating the level of material in a vessel as a function of material capacitance comprising a resonant circuit including a capacitance probe adapted to be disposed in a vessel so as to be responsive to variations in capacitance as a function of material level. An rf oscillator has outputs coupled to the resonant circuit and to a phase detector for detecting variations in phase angle as a function of probe capacitance. Level detection circuitry is responsive to an output of the phase detector and to a reference signal indicative of a predetermined level of material for indicating material level as a function of a difference between capacitance at the probe and the reference signal. An automatic calibration circuit adjusts the resonance characteristics of the parallel resonant circuit. A remote module provides facility for initiating a system-test and a system-calibrate operation, either individually or sequentially.
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