Abstract: A liquid gaging system comprising a plurality of sensors, each sensor providing a liquid measurement signal relating to a liquid depth at a particular location in a tank. The invention also comprises apparatus for selectively monitoring individual sensors one at a time. The apparatus for selectively monitoring is connected to the sensors.

Abstract: A magnetoresistive transducer bridge is operated in a saturation mode by an AC signal in an adjacent conductor. The field produced by the AC signal in the adjacent conductor is of sufficient amplitude to magnetically saturate the bridge elements in a pair of opposite arms of the bridge during most of each half cycle of the AC signal. During each zero-crossing of the applied signal, the bridge comes out of saturation and produces a signal pulse. Thus constituting a zero-crossing detector. This response characteristic is utilized in circuitry producing a current-presence detector, a signal amplitude detector, and a power-factor detector.

Abstract: The invention relates to a test unit for testing the operation and accuracy of a microcomputer controlled aircraft fuel gaging system or processor which involves a characterized liquid gaging system sensor and sensor apparatus for determining a depth of liquid in a tank at a particular location in the tank. The fuel gaging system sensor is the wetted length type capacitance probe. The test unit hereof performs tests on processors prior to their being installed in aircraft and operates to provide a real time simulation of capacitive probes which in effect replaces the aircraft tank and probes thereof in testing the processors. A single reference capacitor simulates by multiplexing the capacitances of the set of tank probes, which in operation are scanned in succession by the processor, to verify the proper operation of the processor.

Abstract: Two condition sensors of two entirely different types are selected and monitored by a single condition sensor interface means. The interface means provides for selection of the sensor to be activated, or can be operated in a mode to repetitively sample both sensors. The sensors rely on a hybrid type device utilizing an integrated circuit, discrete components, and a mounting substrate. The sensors may be mounted on the substrate for temperature stability.

Abstract: A liquid gaging system comprising a sensor for providing a liquid measurement signal related to a liquid depth at a particular location in a tank. The system further comprises storage apparatus for storing data including characterization parameters, each parameter being based on tank shape and volume and on sensor location, each parameter defining a relationship between a liquid depth and a value related to a liquid quantity. The system also includes determining apparatus for determining a value related to a liquid quantity in the tank based on the liquid measurement signal and the data, the determining apparatus being connected to the sensor and to the storage apparatus.

Abstract: A characterized liquid gaging system sensor comprising sensor apparatus for determining a depth of liquid in a tank at a particular location in the tank. The sensor also includes storage apparatus for storing characterization parameters, each parameter being based on tank shape and volume and on the location of the sensor apparatus, each parameter defining a relationship between a liquid depth and a value related to a liquid quantity. The sensor apparatus and the storage apparatus are connected.

Abstract: Circuitry for nulling a signal from a capacitive sensor apparatus with a signal from a reference. The invention includes capacitive sensor apparatus for providing a liquid measurement signal. Also included is reference apparatus for selectively providing a series of reference signals having predetermined amplitudes, the reference apparatus having terminal apparatus for receiving rebalance approximation sequence control signals for selectively controlling the signal amplitudes. The invention further includes null detecting apparatus for detecting the presence of a null, the null detecting apparatus being connected to the capacitive sensor apparatus and the reference apparatus.

Abstract: The present invention is part of a liquid gaging system and comprises an apparatus for self testing the system. Included is an excitation signal generator apparatus for providing an excitation signal and a precision reference component for providing a precise electrical load. The invention also comprises apparatus for monitoring the precision reference component. Also included is apparatus for connecting the precision reference component to the excitation signal generator apparatus and to the apparatus for monitoring.

Abstract: A liquid gaging system including a probe for mounting in a tank. A probe for a particular tank produces a length signal dependent upon the length of the probe being immersed in liquid. The system also includes a storage apparatus for storing characterization parameters and a determining apparatus for determining liquid volume in the particular tank based on the length signal and the characterization parameters. In addition, the system includes an apparatus for connecting the storage apparatus to the determining apparatus and an apparatus for connecting the probe to the determining apparatus.