Abstract: A circuit for detecting arc faults and over-currents includes two overcurrent detection circuits and a ground fault circuit referenced to a single ground and configured to receive power from a single power supply. Each over-current detection circuit includes a Hall effect current sensor configured to determine a current in a corresponding pole conductor. A method for detecting arc faults and over-currents includes determining a current in a pole conductor using a sensor not in contact with the pole conductor. This circuit and method allow a two-pole breaker circuit to be configured in a form similar to a one-pole circuit and eliminate tripping caused by spurious signals from bimetal sensors.

Abstract: A pressurized fluid system provides electrical power to a load and includes a fluid motor, a generator, an energy storage device and a controller. The system supplies fluid to the fluid motor, which provides a generator with power producing a voltage used to supply power to a load and provide energy to the energy storage device. The controller selects which of various sources within the system provides fluid to the fluid motor based on the operating mode of the system. When fluid supplied to the fluid motor is discontinued, the energy storage device discharges providing power to the load.

Abstract: Wide bandwidth compensating circuits are disclosed for compensating for the nonlinearity of other circuits placed in cascade therewith over a relatively wide bandwidth, particularly for high linearity optical modulators, in which first and second versions of a signal are generated having different gains and different nonlinear distortions. The first signal has a higher gain with a lower distortion. The second signal has a lower gain with a higher distortion, and is subtracted from the first larger amplitude signal to form an output signal having a desired nonlinear transfer characteristic over a relatively wide frequency range. A first exemplary circuit has a first higher gain path and a second lower gain path having a transfer characteristic with a substantially greater amount of negative cubic distortion. The first and second signals are subtracted in a wide band differential amplifier to form a resultant signal having a desired positive cubic distortion.

Abstract: A correlator for identifying global positioning satellites includes an antenna at a central location for receiving signature signals from a plurality of the satellites. Each received signal is converted from analog to digital form. A filter is employed to correlate each digital signal with a respective, unique code sequence. Each filtered digital signal is supplied to a circuit which produces an indication that identifies each satellite from the filtered digital signal supplied to the circuit.

Abstract: An apparatus for convening vibratory motion along a predetermined vibration axis to electrical energy comprises an enclosure having first and second opposite walls substantially parallel to one another. A magnet carrier structure in the enclosure also has first and second opposite walls substantially parallel to one another. A pair of springs suspend the carrier structure in the enclosure so that corresponding first walls and corresponding second walls, respectively, face one another with a predetermined spacing therebetween. The springs allow reciprocating movement of the carrier structure relative to the enclosure only along the vibration axis in response to the vibratory motion. Separate magnet sets, each comprising a row of permanent magnets, are attached to a respective outer surface of the first and second walls of the carrier structure for producing a respective magnet flux.

Abstract: An optical communication system includes a first and a second optical communication assembly that are coupled together via an optical coupling medium. Each optical communication assembly includes a respective time delay unit; an optical pattern imager coupled to the time delay unit; a respective transmission-reception apparatus coupled to the time delay unit; and a respective optical signal generator coupled to the time delay unit for passing a pulse of coherent light into the time delay unit. The optical pattern imager in each optical communications assembly is disposed to receive an interference fringe pattern that corresponds to the respective phase shifts introduced by both the transmitting and receiving optical communications assemblies. The position of the interference pattern with respect to a reference standard on the imager provides a signal for a code-key data signal.

Abstract: A distributed delta-sigma analog-to-digital (A/D) converter is partitioned between an ultrasonic probe and an imaging console which are coupled to each other by optical links. The ultrasonic probe houses an integrator for receiving an analog input signal and generating an integrated analog output signal. The integrated output signal is supplied to a light emitting diode for generating a light beam. The probe also houses photoconductive switches for coupling positive and negative reference voltages to a summing node of the integrator. The imaging console houses a photodiode for receiving the light beam via a fiber optic cable and converting the light beam to an analog electrical signal which is later converted to a digital signal. A feedback loop includes an internal A/D converter in the console that is coupled to the photoconductive switches via LED-generated light beams passed through other fiber optic cabling.

Abstract: A mobile tracking unit capable of operating in a power-starved environment for a vehicle tracking system includes a navigation set for generating data corresponding to a respective vehicle position. The navigation set is periodically energized at a selected activation rate F.sub.G while the vehicle is moving to generate the vehicle position data. The tracking unit includes an electromagnetic emitter which is capable of transmitting the vehicle position data and which is periodically energized at a selected activation rate F.sub.EM while the vehicle is moving to transmit at least the vehicle position data. A motion sensor is employed for generating data indicative of vehicle motion. A tracking unit controller receives the vehicle motion data and controls the navigation set and the emitter based upon the vehicle motion data so that when the vehicle is stationary each of activation rates F.sub.G and F.sub.

Abstract: An optical detection system includes an array of photodetectors, each of which is positioned for receiving light and converting the light into an electrical signal. A plurality of high pass filters is positioned with each one of the high pass filters electrically coupled to a respective photodetector for passing a portion of a respective electrical signal having frequency components at least as high as the high pass filter cutoff frequency. In one embodiment, each one of the filters comprises a capacitance coupled to the photodetector and a depletion mode FET with shorted gate-to-source terminals coupled between the photodetector and a bias voltage source.

Abstract: Single-crystal diamond consisting of isotopically pure carbon-12 or carbon-13 has been found to have a thermal conductivity higher than that of any substance previously known, typically at least 40% higher than that of naturally occurring IIA diamond. It may be prepared by a method comprising comminution of diamond of high isotopic purity, such as that obtained by low pressure chemical vapor deposition employing an isotopically pure hydrocarbon in combination with hydrogen, followed by conversion of the comminuted diamond to single-crystal diamond under high pressure conditions.

Abstract: An interferometer Fourier transform spectrometer, having increased speed, is capable of performing a Fourier transform in parallel, in analog form, using a weighted matrix. The spectrometer includes a linear detector array responsive to an interferogram. The detector array is coupled to a plurality of integrating sampling amplifiers. Each column of a group of columns of the matrix is coupled in parallel to a respective integrating sampling amplifier, and the output signals from each row of a group of rows form an output signal array.

Abstract: An instrument for characterizing tumor tissue includes a broad-band light source, a monochromator for filtering collimated light from the broad-band light source, a scanner for scanning the monochromator through a range of predetermined wavelengths, and a hollow needle including a shaft with a tip on one end and a base on the other end. An optical fiber is positioned within the hollow needle for delivering light from the monochromator through the tip to a desired tissue region, A photodiode is mounted in the shaft and has a light sensitive surface facing outward from the shaft for detecting back-scattered light from the tissue region. The back-scattered light detected by the photodiode is monitored by a computer which records the optical absorption spectrum of light back-scattered from the tissue region at discrete locations in the tissue as the needle is inserted or withdrawn through the mammographically abnormal tissue.

Abstract: In an array of charge injection device (CID) detectors, integer amplification is incorporated into each respective detector of the array. The amplifier for each CID detector in the array performs multiple nondestructive readouts. This provides a gain of N amplification of the signal charge in that detector wherein the signal charge is accurately replicated in a separate charge storage well defined by a magnitude capacitor coupled to the detector. Thus, at the end of the readout process, this separate well contains charge equal to N times the signal charge, N being the number of nondestructive readout cycles in the readout process.

Abstract: A spatially resolved map of the eye's refractive characteristics are provided by measuring the eye's refractive characteristics on a point-by-point basis across the anterior surface of the eye. This spatially resolved refraction data may be obtained subjectively by providing a reference pattern and a measurement beam, by establishing a particular position on the cornea as the location to be measured and manipulating the orientation of the measurement beam at that measurement point to bring the measurement beam to a desired position relative to the reference image. When the patient indicates that the measurement beam is in the desired position relative to the reference pattern, the orientation of the beam is recorded as the refractive data for that measurement point and the process proceeds to another measurement point. This provides relatively rapid, physiologically accurate refractive data on a spatially resolved basis.

Abstract: A delta sigma analog-to-digital architecture assures that all channels in a multi-element receiver follow the same compression and/or time-gain variation curve. This is accomplished by varying the reference voltage as a function of time so that the full scale range and associated quantization noise are large at the beginning of the receiving interval and become smaller as more distant echoes arrive. All channels follow the identical gain curve since all channels have the same reference voltage at the same time. The distribution of time-varying reference voltages may be done by using analog buses or by employing a timevarying digital code that specifies the reference voltages derived from a digital-to-analog (D/A) converter. In the latter case, corrections can be applied to the code at each channel.

Abstract: Coherent light is projected through a scattering medium. The light emerging from the medium is a superposition of a multitude of scattered wavelets, each of which represents a specific scattering path. These wavelets are projected onto a diffuse reflecting surface (the viewing plane of a two-dimensional photodetector array) where they interfere with each other, giving rise to a speckle pattern. By introducing a focused ultrasound pulse into the medium, the position of the scatterers are changed at a known location (probe region) in the medium, and this causes a change in the speckle pattern. By comparing speckle images before and after the scatterers are moved, the light absorption properties of the probe region can be measured even though multiple scattering interferes with direct imaging of the region.

Abstract: Apparatus for sensing linear displacement of an object between first and second locations along an axis is used to sense conditions that can be made to vary displacement of an object in accordance with the condition, such as temperature, pressure and rotary motion. A light beam projected along an incident light path to the object is reflected along a reflective light path by a reflector affixed to the object. A photo-sensor array in the reflective light path intercepts the reflected light beam and produces samples of the intensity of the reflected image at multiple positions along a line across the array. An imager coupled to the array converts the light samples to representative electrical samples.

Abstract: A delta sigma analog-to-digital (A/D) converter includes a digitally-controlled multiplying digital-to-analog converter (MDAC) in a feedback configuration. The MDAC is driven by a digital signal obtained from the output (or an intermediate output) of the A/D converter. An incremental feedback quantum to the first stage integrator is a function of the input values that immediately precede it. In the most general implementation, a table look-up permits an arbitrary relation between the input values and feedback quantum size. In another implementation, the A/D converter output (or intermediate output) signal drive the MDAC and the compression curve of the A/D converter bears a square-root relationship to the input analog signal; a linear relationship is restored by squaring the output signal. In a third implementation, the MDAC is driven by a digital signal obtained from the output (or an intermediate output) of the A/D converter together with an added small positive constant number.

Abstract: The invention relates to holography and more particularly to an electronic holographic apparatus whose electrical output represents the magnitude and phase of coherent light reflected from a three-dimensional object and distributed over the aperture of the apparatus. The apparatus provides a coherent beam which illuminates the object to create a speckle pattern in an aperture bounding an optical sensing arrangement. A reference beam derived from the same source as the illuminating beam illuminates the sensing aperture directly and creates fringes in the speckle pattern. The optical sensing arrangement consists of a charge injection device (CID) camera with plural optical detectors arranged in relation to the speckle pattern to sense the magnitude and spatial phase of each speckle (on the average).

Abstract: A high resolution analog-to-digital (A/D) converter (14) and a pipelined A/D converter are used in a single system so that unknown offset and gain errors of the pipe-lined A/D converter are determined and corrected. Each stage of the pipelined A/D converter includes a flash A/D converter (16), a corresponding digital-to-analog (D/A) converter (18), and a differential amplifier (20) so that, in each stage the output voltage of the D/A converter is subtracted from a sample of the analog input voltage, to constitute the input signal for the next stage. The flash A/D converter of each stage addresses digital words in memory (22) which, when summed by an adder chain (24), constitute the output signal of the system. The flash A/D converter output signals are also supplied to corresponding stages of a shift register (28 or 28') which accumulates the memory address bits.