System for automatic real-time calibration of remotely-located capacitive- type fuel quantity measurement probes

摘要

A system including a method and means for trimming capacitive- type remotely-located fuel probes that eliminates the previously-used variable trim capacitor and substitutes a rugged, inexpensive, standard- value signature resistor connected between the AC input and ground to provide "calibration offset" data needed by the fuel measurement electronics to make a determination of actual probe capacitance. The system may be applied to any such probe having a blocking capacitor in series with the probe capacitor, which blocking capacitor insures accurate measurement of the signature resistor when the leakage resistance is significant. When applied to DC or AC FHC probes, the C.sub. fhc capacitor is replaced with a non-critical DC-blocking capacitor, that is typically at least 100 times greater in capacitance value than the C. sub.probe capacitor, and then a software modeled FHC algorithm may be used along with the signature resistor value, which acts as a pointer to a lookup table, to provide accurate, real-time calibration of the probe.