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 circuit comprising a signal generating circuit and an interrupt enable circuit. The signal generating circuit has an input connected to receive a trigger signal and an output for generating an output signal which includes a timing cycle of known duration. The signal generating circuit is responsive to the trigger signal for initiating the timing cycle. The interrupt enable circuit is connected to the signal generating circuit for interrupting the timing cycle in timed relation to an interrupt signal and for reinitiating the timing cycle in timed relation to a reset signal, the interrupt enable circuit being connected to receive the interrupt and reset signals. The output signal begins in timed relation to the start pulse and terminates in timed relation to the end of the timing cycle following interruption.

Abstract: Circuitry for generating a virtually jitter free delay relative to a start pulse and for generating such delays over both integer and non-integer multiples of the time interval between timing pulses. The circuitry includes delay circuitry and signal generating circuitry. The delay circuitry is responsive to the start pulse and to the timing pulses for generating first and second signal edges. The second signal edge occurs later in time than the first signal edge, and both signal edges occur following the start pulse and in timed relation to the timing pulses. The signal generating circuitry is connected to the delay circuitry and has an output for generating an output signal which includes a timing cycle of known duration. The signal generating circuitry is responsive to the start pulse for initiating the timing cycle, the first signal edge for interrupting the timing cycle, and the second signal edge for reinitiating the timing cycle.

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.

Abstract: A light emitting and light detecting semiconductor device having a light emitting zone and a light detecting zone adaptable for concurrently interfacing with an optical fiber.

Abstract: An electronic circuit to be used in conjunction with eddy current non-destructive flaw detection instrumentation for distinguishing from noise or other undesirable signals a flaw signal having a characteristic frequency and a negative excursion followed by a positive excursion. The circuit includes two channels, each of which comprises a threshold detector, a differentiator, a filter, and a variable pulse width one-shot multivibrator, each of which receives the characteristic signal. One channel processes the negative excursion, and the other channel processes the positive excursion. Each channel produces a pulse of predetermined time duration if the excursion being processed exceeds a predetermined threshold. The leading edge of the pulse produced in association with the negative excursion corresponds in time to the time at which the trailing positive going edge of the negative excursion crosses a predetermined negative threshold.