Abstract: System and method of error reduction in which a comparator is sequentially operated to produce series of pulses in which the time distribution of the pulses is related to the displacement being monitored by the transducer. In particular, the comparator is sequentially operated to provide two sets of pulses using a positive ramp voltage, and then using a negative ramp voltage having a magnitude equal to the positive ramp voltage. Averaged time periods between the pulses are used to eliminate offset errors in the determination of the value that the transducer is monitoring. The transducer is adapted to monitor the substantially linear movement of the level (fuel-air interface) of fuel in a tank and the angular position of an input shaft.

Abstract: A method and system determines the density of a liquid, such as aircraft fuel, by measuring the amplitude of the reflections of ultrasonic pulses from the faces of the walls of a reference material. A transducer is used to transmit an ultrasonic interrogation pulse through a liquid to the reference material. The density of the reference material is known, and its boundaries are well defined. The interrogation pulse is reflected from the faces of the reference material boundaries to provide first, second and third return pulses that can be used to determine the density of the liquid. The density determination is accomplished by determining characteristic impedances, reflection coefficients and transmission coefficients as a function of the returned pulse amplitudes.

Abstract: A displacement detector provides a light beam which impinges on an article with different combinations of light altering materials such as reflecting and non-reflecting surfaces, wave retarding plates, and linear polarizers attached to the article to determine angular position, relative angular displacement, and speed of rotatably mounted articles. These beam altering materials change either the polarization state or the magnitude of the light in a predictable manner. When used on different ends of a rotating shaft, the shaft speed and torsional displacement of the front shaft end with respect to the rear shaft end can be determined. When used with an article such as a rotatably mounted throttle, the angular displacement of the throttle can be determined.

Abstract: A rotating shaft torsional displacement and speed detector provides a light beam which impinges on one or both ends of the rotating shaft. Different combinations of beam altering materials such as reflecting and non-reflecting surfaces, wave retarding plates, and linear polarizers are attached to the front shaft end and rear shaft end. These beam altering materials change either the polarization or magnitude of the light beam in a predictable manner that allows for the detection of shaft speed and torsional displacement of the front shaft end with respect to the rear shaft end.