Abstract: A local oscillator frequency measurement system for measuring the frequency of a local oscillator of an ESM receiver. The frequency measurement system includes a global positioning system (GPS) receiver (20) for providing a GPS pulse time and time interval signal; a threshold detector (45) responsive to the GPS pulse time and time interval signal for detecting pulses in the GPS pulse time and time interval signal for providing an output indicative of the occurrences of the pulses; a counter (41) clocked by the output of the local oscillator for providing a counter output; a latch (43) for sampling the counter output pursuant to detection of the pulses to provide sampled counts, whereby the sampled counts represent the outputs of the counter at the time the pulses are detected; and a processor (50) for processing the sampled counts to determine the frequency of the local oscillator.
Abstract: An optical mount secures an optical component so that its freedom of movement is restricted in all directions. The mount uses a spring retainer assembly to urge the optical component against various faces of the mount. The mount is especially well suited for work with crystals, such as frequency doubling or optical parametric oscillation crystals.
Abstract: A current source that uses a regulated constant current power source to supply current to drive a load, and the load current is controlled by shunt switches. If a plurality of loads utilize less than 50% duty factor, then one current source can drive N multiple dissimilar impedance loads, each at 100%/N duty factor. The current source includes a power converter coupled between the power source and the load(s) for providing pulsed current thereto. A current sensor is provided for sensing current flowing through the loads. A controller is coupled between the sensor and the power converter for regulating the amplitude of the output current supplied to the loads. A shunt switch is coupled across the loads, and a duty factor controller is coupled to the shunt switch for setting the duty factor of the shunt switch. A laser drive circuit, or driving light emitting diode arrays is also disclosed that include a plurality of the current sources.
Abstract: A method and system for providing video on demand from a database of textual information. In accordance with the inventive method, video data is stored on an addressable medium. The addresses for video segments are stored for retrieval when corresponding textual information is accessed in the database. In a particular embodiment, the addresses are stored in a lookup table which is read whenever a section of textual data is accessed. When the table indicates that video is available, corresponding to the text being viewed, an icon is displayed on the screen. When the video option is exercised, the address for the video segment is retrieved from the table and used to access the video storage medium. Video from the medium is then displayed interactively. The invention thus provides a system and technique for providing access to live action video at appropriate locations in a computer database.
June 6, 1995
Date of Patent:
April 7, 1998
Hughes Missile Systems Company
Charles M. DeLair, Grant Schmieder, Mark S. Sprague, Kenneth W. Virgil, Anthony F. Zucco
Abstract: A linear displacement device (1) is provided with a lead screw (24) having a helical threaded portion (70) and a roller nut assembly (10). The roller nut assembly (10) includes a housing (50) having openings (52, 54) for receiving the lead screw (24) therethrough. A pair of bearings (56, 58) are supported within said housing (50). The bearings (56, 58) each have an inner race (60), an outer race (62) and a plurality of balls (64) disposed between the inner and outer races (60, 62). A spring (94) is disposed between the pair of bearings (56, 58), for biasing the bearings (56, 58) apart. The bearings (56, 58) are provided with a flank engaging portion (66) for engaging the flank (68, 72) of a helical threaded portion (70) of the lead screw (24) and a crest contacting portion (74) for engaging a crest (76) of the helical threaded portion (70) of the lead screw (24).
Abstract: A driver circuit for regulating the current flowing through the coils of a rotary field microwave phase shifter. The circuit includes logic circuitry functions which implements an algorithm to provide decision making capability to avoid failure-inducing conditions, reducing power consumption, and enhancing testability of the circuit. The circuit includes two switches that respectively drive either a positive or a negative voltage to the load, to begin steering the load current to the appropriate direction. The logic circuitry includes a current mode mapping function to determine whether a commanded current value requires positive, negative or no voltage applied to the load. The logic circuitry further includes a finite state machine to control the two switches, to ensure that both switches are never commanded to be conductive at the same time, and to permit toggling of only one of the switches to regulate the current to a target value in a feedback loop.
Abstract: A controllable precision delay line implemented in a digital integrated circuit device including a counter circuit for measuring a representative propagation delay for a delay element in the digital integrated circuit, and a binary controlled digital delay line responsive to the counter circuit and including L delay stages respectively having 2.sup.0 through 2.sup.L-1 delay elements, wherein the delay stages are controllably switched into a delay path pursuant to the measured representative propagation delay. Preload connections are provided between the outputs of delay elements of stages S(0) through S(L-2) and inputs of delay elements of the next in sequence stages S(1) through S(L-1) to prevent glitches being imposed on the delayed signal during adjustments in the number of stages included in the delay path.
Abstract: A fin blanket for attenuating radio-frequency scattering, thereby protecting a surface such as a feed-horn or radiator panels of a spacecraft. The fin blanket includes a plurality of fins formed of a microwave absorbing film, each fin including at least one planar side positioned generally parallel to an electric field formed by the radio-frequency scattering.
Abstract: A slide rule permits rapid calculations of parameters used in the Six Sigma quality analysis program. For a given number of defects per product and a known number of parts per product (opportunities), the device permits rapid calculation of the number of defects per million opportunities as well as various statistical relationships, with a single movement of the slide.
Abstract: The operating point of a nonlinear amplifier is determined by injecting a known test signal into the communication channel and measuring the gain of the amplified test signal. Each amplifier is characterized by a small signal gain curve that relates the gain of the test signal to the input power of the amplifier. In the amplifier's nonlinear range, the gain uniquely determines the input power level of the amplifier, which in turn uniquely determines the operating point of the amplifier. The invention is particularly applicable to satellite transponder architectures that employ "burst" transmission schemes and phased array antennas.
Abstract: A virtual image instrument panel display (20) has a display source (22) and reflective elements (24, 26). The display source (22) generates a beam (28) including an image to be viewed. The reflecting elements (24, 26) receive the beam and provide a virtual image of the image of the beam. The virtual image is focused on a viewing plane at a predetermined and substantial virtual distance away from the user to enable easy eye focus transition between the virtual image and distant objects. The folded nature of the optical system provides for a compact package suitable for installation in an automotive dashboard.
Abstract: A memory cell is constructed using a ferroelectric capacitor having an insulator formed of a ferroelectric material that has a zero field capacitance which is controllably dependent upon the electrical charging path by which the zero field capacitance is reached. Preferably, the material is characterized by a first zero field capacitance following saturation of the polarization by a first applied voltage applied in a first polarization direction, and a second zero field capacitance following saturation of the polarization by the first applied voltage applied in the first polarization direction followed by partial depolarization by a second voltage applied in a direction opposite to the first polarization direction. A second ferroelectric capacitor or a linear capacitor may be placed in parallel with the ferroelectric capacitor to form a two-capacitor memory cell. Data may be read to or from the capacitor cell without impairing the state of the stored data.
Abstract: A receiver used in a system having a transmitter (10) that sends an exciting signal to a remote transponder (18) is configured to receive a relatively weak signal from the transponder and to cancel out relatively high level interference from the transmission itself. A received frequency shift keying signal is fed to a tuned amplifier (22) for preliminary analog signal conditioning, and thence fed to an analog to digital converter (24). The output of the analog to digital converter is integrated (26) over a selected number of clock pulses and then dumped into a quarter rate quadrature demodulator (60) that multiplies the integrated signal by the same signal delayed by one clock interval. Undesired artifacts generated in the demodulator (60) are removed by a cascade of comb filters (70), and the demodulated digital output is available as the desired output of the receiver.
April 30, 1996
Date of Patent:
March 17, 1998
Wade J. Stone, Robert Tso, John M. Burns
Abstract: A low cost night vision system for use in connection with law enforcement vehicles, marine vessels, and other nonmilitary surface vehicles. The invention includes a night vision camera having an array of uncooled detectors. A mechanism is provided for adjusting the pointing angle of the night vision camera in response to scan control signals. Output signals from the uncooled detectors are further processed into a standard video format and displayed on a conventional display located, for example, within a vehicle or marine vessel.
August 26, 1996
Date of Patent:
March 17, 1998
Hughes Aircraft Company
Stuart H. Klapper, Howard Laitin, Alex L. Kormos, Lacy G. Cook, David M. Masarik, Paul R. Salvio
Abstract: A multiple image multiplexed holographic display including a light pipe (11, 111) having first and second opposing surfaces (11a, 11b, 111a, 111b) and a plurality of input surfaces (15, 115) located between adjacent edges of the first and second opposing surfaces. A multiple image hologram structure (13, 113) attached to one of the first and second opposing surfaces is illuminated with respective beams injected into the light pipe by a plurality of light sources (17, 50, 61) adjacent respective input surfaces. The injected beams are incident on the hologram structure at different incidence angles, and the hologram structure contains holographic images that are recorded to reconstruct in response to respective injected beams, whereby each holographic image is selectively displayed by controlling its associated light source.
Abstract: An automated system and method for testing a sensor by evaluating the output thereof with respect to a known target. The advantageous method includes the step of acquiring an output signal from the sensor in response to a known target, said output including signature signal S, random noise N.sub.R and fixed pattern noise N.sub.FP. Next, the sensor output signal is processed to provide a first signal which includes essentially signature signal S and fixed pattern noise N.sub.FP, a second signal which includes essentially random noise N.sub.R and a third signal which includes essentially fixed pattern noise N.sub.FP. The third signal is adaptively filtered to provide a filtered signal fixed pattern noise signal N'.sub.FP. The filtered signal N'.sub.FP is subtracted from the first signal to extract a signature S. In a particular embodiment, the signature is processed to acquire a modulation transfer function and a signal peak baseline therefrom.
Abstract: A head mounted projector system with extremely high resolution. The system includes a retro-reflecting gain screen. The on-helmet apparatus of the system includes a truncated spherical mirror, a redirecting multi-faceted mirror and a small rotating polygon scanner. The system includes off-helmet apparatus including a background image source and an area-of-interest (AOI) image source. The background and AOI images are scanned into a linear ribbon array of fibers. To provide 20/20 visual acuity, one fiber per each 0.7 arc-minute field-of-view is used.
Abstract: Test equipment and test methods employing signature analysis to achieve fault isolation of parts contained in digital modules. Fault free signatures of a digital module are stored in a lookup table that are derived from physical measurement or simulation of all parts. All of the parts in the functional digital module are shorted and opened (either physically or by simulation) and each of their resulting faulty signatures are recorded in a storage device. Each signature with its corresponding faulty part is stored in the lookup table or memory. Test input signals are then applied to a tested digital module, and outputs of all parts thereof are applied to masking circuitry which allows sequential selective masking of all parts but one, for each part on the tested digital module. Outputs of the masking circuitry are applied to a multiple input shift register signal analyzer that performs pass/fail signature analysis using the applied signals.
Abstract: An improved circuit and method of making precise time of arrival measurements on optical pulse data of relatively varying widths. The invention provides an analog input pulse representing received optical pulse data, along with a delayed version of the analog input pulse. The time of delay is set such that the original analog pulse and the delayed analog pulse cross each other at a predetermined point. This cross-over consistently occurs at the same point on the signal independent of the size or shape of the analog pulse. Preferably, the cross-over occurs at approximately 70% of the analog pulse amplitude. The cross-over point between the original pulse and the delayed pulse triggers the generation of the leading edge of a time of arrival pulse.
Abstract: A low profile, compact microstrip-to-waveguide or stripline-to-waveguide transition. The end of the waveguide is terminated in a cavity backed slot defined in a groundplane formed on a dielectric substrate. The slot is excited by a microstrip or stripline conductor defined on the opposite side of the substrate. The conductor is terminated in a T-shaped junction including two opposed arms extending along the slot, each having a length equal to one-quarter wavelength at the center frequency of operation. A cavity covers the substrate on the conductor side, and is sized so that no cavity modes resonate in the frequency band of operation. The transition is matched by appropriate selection of the length of the slot and the length and position of the microstrip.