Abstract: A system and method for providing a constant rate of sparking in the spark gap of an internal combustion engine by supplying constant power to the capacitor which discharges through the spark gap. The capacitor receives current from the secondary coil of a transformer. The system uses a multivibrator to control current flow through the primary circuit of a transformer. The multivibrator is controlled by a comparator which compares an integrated transformer feedback signal to a temperature compensated reference voltage. In any two equal time periods, substantially the same amount of current flows to the capacitor from the secondary of the transformers. Substantially the same number of sparks are discharged through a spark gap during equal time periods.

Abstract: An optical fiber mounting device and method of installation and monitoring of a structure using the device. The device includes an optical fiber connected to a support sheet. The support sheet is readily adapted to be connected to a structure. The method of installation of the device includes affixing the support sheet to a structure. The fabricated structure is monitored by propagating light through the installed optical fiber and continuously monitoring the light to detect changes in temperature, pressure, stress and/or strain in the structure.

Abstract: A connector device and method of use thereof provide positioning and hermetic sealing of electrical contacts in protective housings. The housings protect wires which connect the speed sensor of a turbine engine to a display. The connector supports the electrical contacts in an electrical insulator. The connector includes a malleable flange which is adapted to be hermetically sealed between two housings which protect wires connected to the speed sensor in the turbine engine. The flange is hermetically sealed between a tongue on one housing and a groove in the other housing. The sealing flange extends radially from the central axis of the connector and is compressed by the tongue of a releasable housing into the groove of a permanent housing to form a hermetic seal. The flange supports the electrical insulator which holds electrically conducting inner contacts in position to be slideably mounted into outer contacts which are supported by the connector housing.

Abstract: The sensor and method of monitoring of the invention uses light diffracted from diffracting elements having at least one region of nonuniformity. The sensor is useful for monitoring displacement, stress, temperature and pressure. In one form of the invention, a diffraction grating is fabricated from first and second gratings and has a step-wise change in the grating period at an inter-grating boundary. The grating is illuminated with broadband light that is diffracted as a function of the irradiated position on the grating with the wavelength of the diffracted light and the change in wavelength being a function of the diffraction grating position. In another form of the present invention, a diffraction grating is provided with a variable grating period than can vary linearly, exponentially, or in accordance with some other function with the wavelength of the diffracted light being a function of the relative displacement of the grating.

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: The sensor and method of monitoring of the invention uses light diffracted from diffracting elements having at least one region of nonuniformity. The sensor is useful for monitoring displacement, stress, temperature and pressure. In one form of the invention, a diffraction grating is fabricated from first and second gratings and has a step-wise change in the grating period at an inter-grating boundary. The grating is illuminated with broadband light that is diffracted as a function of the irradiated position on the grating with the wavelength of the diffracted light and the change in wavelength being a function of the diffraction grating position. In another form of the present invention, a diffraction grating is provided with a variable grating period that can very linearly, exponentially, or in accordance with some other function with the wavelength of the diffracted light being a function of the relative displacement of the grating.

Abstract: An optical frequency domain distributed strain sensor for determining the strain distribution along an optical fiber includes an optical source that provides a polarization controlled optical interrogation signal having a frequency that varies in a recurring linear manner. The interrogation signal is injected into a sensor fiber embedded within a composite structure that places the fiber under strain. A portion of the interrogation signal is backscattered from the sensing fiber as a consequence of the strain experienced by the fiber and is mixed with a reference signal to produce beat frequency signals. The frequency of the beat signals is directly related the to position of backscatter in the sensing fiber while the amplitude of each beat frequency signal is directly related to the integrated strain-induced birefringence up to the backscatter point.

Abstract: Apparatus and method for determining capacitive and resistive values of an electrical component, such as a fuel level determining probe, includes a waveform generator for subjecting the probe to a time-varying waveform that includes a linearly varying ramp portion and a fixed, constant portion. A selectively controlled sample and hold circuit senses the voltage potential of the probe in response to a zero-crossing detector during the linearly varying ramp portion of the waveform to provide information indicative of the capacitive value and again senses the voltage potential at selected time thereafter during the fixed portion of the waveform to provide resistive value information. The output of the sample and hold is provided to an analog-to-digital converter which provided digital information to a stored-program controlled processor which provides the desired output information.

Abstract: A system and method of operation of a jet aircraft for a specific flight. The mass of liquid fuel in the aircraft's fuel tank is determined from the actual heating value of the fuel, based upon its density and temperature. The flight time available from the amount of fuel in the tank is determined and displayed. At least the amount of the fuel required for a specific flight is loaded into one or more fuel tanks on the aircraft.

Abstract: An optically powered sensor system with improved signal conditioning includes a plurality of sensors connected to a system optical bus that communicates with a system controller. Optical energy is transmitted along the bus for distribution to all sensor in the system with return pulses from the various sensors transmitted on the bus to the system controller. Each sensor includes a photodiode array for converting optical energy transmitted system-wide by the controller into electrical energy for storage in a storage capacitor associated with each sensor. A capacitance probe transducer and a fixed-value reference capacitor are connected to a resettable integrating pulse encoder that produces a series of short-duration pulses having a pulse spacing that is dependent upon the fixed value of the reference and the parameter-affected value of the transducer. The pulses are used to drive an optical source for transmitting optical pulses from the sensor to the system controller.

Abstract: The system and method provide an electrically passive optically controlled acoustic transceiver system which measures the quantity of a liquid, such as aircraft fuel, in a tank. Pulsed electromagnetic radiation, such as light or infrared radiation, is guided through an optical fiber and impinged upon a flexible member adapted to flex when heated and transmit acoustic pulses. An optical fiber detector, is used to monitor the acoustic pulses reflected from the liquid level in a fuel tank. The system is electrically passive and does not require or use electrical power at the sensing location.

Abstract: An optical fiber mounting device and method of installation and monitoring of a structure using the device. The device includes an optical fiber connected to a support sheet. The support sheet is readily adapted to be connected to a structure. The method of installation of the device includes affixing the support sheet to a structure. The fabricated structure is monitored by propagating light through the installed optical fiber and continuously monitoring the light to detect changes in temperature, pressure, stress and/or strain in the structure.

Abstract: The method of the invention provides for actuating at least one actuator, such as a piezoelectric transducer in response to movement of a waveguide, such as an optical fiber. In a preferred embodiment of the invention, both the piezoelectric member and the optical fiber are connected to a structure. The connection is such that movement of the structure is detected by corresponding variations in and/or back scattering from light transmitted into the optical fiber. The piezoelectric member is actuated in response to the movement of the structural member as detected by the variations in the light in passing through the optical fiber. The actuation of the piezoelectric member may effect a dampening of the initial structural movement. Alternatively, monitoring the light passing through the fiber may be used as feed back on the position of the structural member, which in turn may be used to reposition the structural member by further actuation of a piezoelectric member.

Abstract: A liquid level sensor system well suited for sensing the level of fuel in aircraft fuel tanks includes a plurality of capacitive sensors which provide an output capacitance that is a function of the fraction of the sensor wetted by the fuel. A plurality of sensors are positioned in the liquid-containing tank with each sensor having a first and at least a second probe-specific liquid-quantity profile corresponding to a first and at least a second attitude of the tank. The capacitance of the sensors are determined as function of the length of the respective sensor wetted by the liquid. A memory is provided with a first and second sets of address locations containing liquid-quantity profile information for the sensors for their respective first and second attitudes. The memory is addressed by determining an address offset as a function of the attitude of the system, the relative location of the profile information for the sensor, and the fraction of the sensor wetted by the liquid.

Abstract: A sensor testing apparatus which is capable of testing any sensor regardless of the type of polarization the sensor is sensitive to. The testing apparatus comprises a source conditioning apparatus to produce a beam of optical energy of a known polarization state. A polarization conditioning apparatus changes the polarization state of the optical energy beam to any desired polarization state. A transmit quadrant detector detects the polarization of the optical energy and the optical energy is directed to a sensor to be tested. The optical energy transmitted by the sensor is detected by a receive quadrant detector. The polarization state is displayed on the monitor of a computer by virtue of a computer interface with both quadrant detectors.

Abstract: The system and method provide an electrically passive optically controlled acoustic transceiver system which measures the quantity of a liquid, such as aircraft fuel, in a tank. Pulsed electromagnetic radiation, such as light or infrared radiation, is guided through an optical fiber and impinged upon a flexible member adapted to flex when heated and transmit acoustic pulses. An optical fiber detector, is used to monitor the acoustic pulses reflected from the liquid level in a fuel tank. The system is electrically passive and does not require or use electrical power at the sensing location.

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 transducer system that uses diffracted light energy in a transducer application analyzes light diffracted from a diffraction grating to provide an indication of displacement or other measurable environmental changes, such a temperature changes. In one form of the invention, a diffraction grating is fabricated from first and second gratings and has a step-wise change in the grating period at an inter-grating boundary. The grating is illuminated with broadband light that is diffracted as a function of the irradiated position on the grating with the wavelength of the diffracted light and the change in wavelength being a function of the diffraction grating position. In another form of the present invention, a diffraction grating is provided with a variable grating period that can vary linearly, exponentially, or in accordance with some other function with the wavelength of the diffracted light being a function of the relative displacement of the grating.

Abstract: A connector device and method of use thereof provide positioning and hermetic sealing of electrical contacts in protective housings. The housings protect wires which connect the speed sensor of a turbine engine to a display. The connector supports the electrical contacts in an electrical insulator. The connector includes a malleable flange which is adapted to be hermetically sealed between two housings which protect wires connected to the speed sensor in the turbine engine. The flange is hermetically sealed between a tongue on one housing and a groove in the other housing. The sealing flange extends radially from the central axis of the connector and is compressed by the tongue of a releasable housing into the groove of a permanent housing to form a hermetic seal. The flange supports the electrical insulator which holds electrically conducting inner contacts in position to be slideably mounted into outer contacts which are supported by the connector housing.

Abstract: A method and apparatus for monitoring the rate of rotation of a turbine engine shaft during the operation of the engine. A chopper extends radially from the shaft. Infrared radiation is passed through an input optical fiber having a beveled end positioned adjacent to the chopper which chops the infrared radiation. The chopped infrared radiation passes into a beveled end of an output optical fiber which is positioned adjacent to the chopper. The rate of rotation of the shaft is detected by monitoring the chopped infrared radiation from the output optical fiber. Carbonaceous coatings are formed on the beveled ends of the optical fibers by deposition of oil and combustion products thereon. While these coatings are opaque to visible light, they are transparent to the infrared radiation used in accordance with the invention.