Abstract: A system for use with an inertial reference system and a global position receiver for calculating a position error after a loss of integrity by utilizing the global position system values for position and velocity at a time just before the loss of integrity and by utilizing the inertial reference system position modified by the known error in inertial reference system position as it varies with time and the position error as calculated by the global position system velocity extrapolated over the time since integrity loss.

Abstract: A wave-based detection system according to various aspects of the present invention analyzes signals in conjunction with a series of thresholds related to the anticipated input power of the incoming signals. The system implements a scheduled gain system to optimize the dynamic range according to the operating configuration of a transmitter and the characteristics of the receiver. The thresholds are correspondingly scaled using the scheduled gain. Because the thresholds are determined by an algorithm instead of a look up table, with the algorithm being based solely on the anticipated input power, the system uses significantly less memory and empirical data.

Abstract: A self adaptive limiter for use in aircraft control systems during approach and landing is disclosed. Estimated flight path angle is continuously computed during the glidepath tracking phase until a predetermined lock altitude above ground when a nominal flight path angle is latched. Nominal vertical speed is continuously computed below the lock altitude as a function of the latched nominal flight path angle and ground speed of the aircraft. A vertical speed limit function is generated as a function of the nominal vertical speed and radio altitude. During approach and landing a pitch limit is computed from the vertical speed limit, vertical speed, ground speed, and pitch. When a pitch command to the autopilot exceeds the pitch limit(i.e. commands excessive pitch down attitude), it is limited to the pitch limit thus preventing the aircraft from descending below a safe altitude.

Abstract: A system to alter the voltage supplied to the linear regulator of a pulsed transmitter in accordance with the temperature of the regulator, the minimum voltage required for a transmission and the specific aircraft installation requirements so as to reduce problems of heat dissipation in the regulator.

Abstract: A Traffic Alert and Collision Avoidance System(TCAS) antenna is mounted on a selected forward portion of an aircraft thereby extending the effective forward range of the TCAS. The antenna and ground plane are tilted relative to conventional TCAS antennas thereby aligning a peak of the antenna's radiation pattern along the aircraft's level line of flight. The resulting increased gain directed forward of the aircraft increases the forward range of the TCAS for both receiving and transmitting TCAS signals. The invention is also useful to extend the range of other aircraft systems including transponders. Alternate embodiments include tilting a conventional TCAS antenna mounted on a middle portion of the aircraft.

Abstract: An aircraft display combines speed error tapes and multiple speed reference bugs to produce a display which reduces pilot workload. The length of the speed error tape is indicative of the difference between a current aircraft speed and a reference speed. Multiple reference bugs are adjacent to the error tape and are indicative of the difference between the current aircraft speed and other selected reference speeds. The reference bugs move along the error tape thereby communicating the status of the current aircraft speed relative to the multiple reference speeds. The display reduces the need for the pilot to scan and analyze numerous instruments for the same information.

Abstract: A backscatter or secondary wave error reducer for an interferometric fiber optic gyroscope having at least one phase modulator for receiving a square wave bias phase modulation signal and a sine wave carrier suppression modulation signal. The amplitude of the carrier suppression modulation signal is sufficient to greatly reduce the interference between two sets of backscattered or secondary waves of light originating in the Sagnac loop of the gyroscope. Reduction or elimination of the interference of the two sets of secondary waves reduces or eliminates the secondary wave induced rotation rate sensing error. The frequency of the carrier suppression signal is near or equal to an even harmonic of the proper frequency of the Sagnac loop to reduce the sinusoidal or periodic rotation rate sensing error caused by the carrier suppression modulation signal.

Abstract: An aircraft control system improves system flexibility, scalability, redundancy, and separation. The system uses a "virtual backplane" architecture which maximizes system flexibility and scalability and allows easy integration of new functions. The architecture comprises four major elements: processing modules; input and output modules (i.e. I/O modules); database modules; and an aircraft wide system network. Inter module communication occurs via the aircraft wide system network thereby eliminating the need for point to point communication and making modules independent of physical location or what modular units (MUs) they are in. Predetermined periodic and deterministic broadcast techniques improve the safety and communications efficiency of the system.

Abstract: A subtractive color liquid crystal display employing circular polarizers. In the subtractive color display each picture element has three liquid crystal switching elements. Adjacent to each liquid crystal switching element are a circular polarizer and 1/4 wave retarder plate combination. The circular polarizer and 1/4 wave retarder plate combination create a linear notch polarizer for an isolated and steep polarization band for each of the primary colors (red, green blue). The notch polarizes are tuned to the particular backlight of the display in order to provide increased light transmittance and color gamut.

Abstract: An aircraft display communicates three dimensional lateral information to a pilot of the aircraft. An extended course centerline symbol and lateral deviation marks indicate lateral deviation from a desired course along with approximate altitude and distance-to-go information to the pilot. The course centerline extends toward a vanishing point near the horizon line of the display. The centerline symbol swings laterally across the display responsive to changes in lateral deviation of the aircraft such that an intuitive perspective view is provided to the pilot. Lateral deviation marks provide precise lateral deviation information to the pilot. The display is adaptable to all phases of flight, but is particularly useful during the approach phase of flight. The preferred embodiment is on a head-up display for instrument flight conditions.

Abstract: An ambiguous dial indicator intuitively communicates the relative value of setpoints to an operator. The ambiguous dial indicator includes an ambiguous scale and a pointer or needle. The setpoints are represented by "bugs" which are adjacent to the ambiguous scale. The bugs are limited to a predetermined range about the pointer such that when a setpoint is outside of the predetermined range the associated bug is limited to an edge of the range. When several setpoints are outside of the predetermined range the several associated bugs saturate or park at the edges of the range. The invention is particularly useful in head-up displays and helmet mounted displays.

Abstract: A circuit measures the driving and circulating current in an H-bridge drive network directly and linearly. Voltage across two current sensing resistors are input to two precision half-wave rectifiers. The output of the rectifiers are input to a differential amplifier via a circuit of resistors. The output of the differential amplifier is a signal representative of the current in the H-bridge for both the driven periods and non-driven or freewheeling periods.

Abstract: Airplanes have transponders which receive and transmit signals to communicate information regarding the flight of the airplane. A transponder testing apparatus is integrated into the transponder and verifies that the transponders are operating in accordance to Federal Aviation Regulations.

Abstract: The disclosure is directed to a color liquid crystal display backlight system for daytime and nighttime use. Night vision imaging system retirements are met so that light emissions from the 630 nm to 930 nm range are substantially reduced or eliminated. Separate daytime and nighttime light sources are utilized. The NVIS compatible nighttime source is positioned to be out of sight of a user and produces an appropriately filtered, substantially collimated beam which diffusively reflects from the inside walls and base of the display housing before it illuminates the display surface. Intensities of both daytime and nighttime light sources can be controlled.

Abstract: A novel bias circuit provides precise base emitter voltage(V.sub.BE) which tracks the temperature coefficient of an RF transistor using low cost devices. The bias circuit includes a precision current source which injects current through a P-N junction device to derive a temperature compensating reference voltage thereacross. The P-N junction device is isolated from current fluctuations using a current isolation circuit coupled between the P-N junction device and the base of the RF transistor. The diode is thereby isolated from and unaffected by changes in the base current of the RF transistor. Multiple RF transistors are biased from the single P-N junction device by replicating only a trimming potentiometer and the current isolation circuitry for each additional RF transistor to be biased.

Abstract: An apparatus for providing lateral guidance through a plurality of waypoints utilizing curved path transitions. When the curved path transitions overlap due to a short leg there is a discontinuity in the desired path of the aircraft, causing the aircraft to experience excessive and oscillatory bank angles to maneuver through the turn. The invention adjusts the transition parameters so that there are no discontinuities in the flight path by computing a new turn radius, turn center, or turn center coordinates, in accordance with the course through the waypoints. The invention determines which flight plan legs are short and calculates the parameters so that the path will not violate air space boundaries and bank angles will be minimized. A circular path is generated tangential to course changes in the same or opposite direction, irrespective of the value of the flight plan leg length.

Abstract: A liquid crystal display having pixels illuminated by field emitter arrays. The field emitter arrays may be utilized to illuminate each pixel individually or to be a backlight lamp to illuminate the whole display, whether monochrome or color. A field emitter array back-lighted liquid crystal displays, whether active matrix or passive, provide greater compactness, higher luminous efficiency, more brightness, and longer lifetime than a fluorescent lamp. Field-emitter arrays may also provide light in various colors for the liquid crystal display thereby eliminating the need for color filters which result in duller colors than that of field emitter arrays. Each color filter absorbs two-thirds of the light that it receives. A color filter liquid crystal color display exhibits colors that have diminished chromaticity and purity in comparison to those of a field emitter array liquid crystal display.

Abstract: The virtual graphics processor is a software process that enables different video display systems to execute the same graphical display application. The process also permits the display application to be updated or reconfigured in real time without changing the embedded display system software. The parts of the virtual graphics processor include an application graphics database for storing graphic primitives and associated static primitive data defining one or more graphic pages in a display application. An image control interface (video library) associates graphic functions of the particular video display system with graphic primitives in a requested page. An instruction sequencer within the virtual graphics processor responds to a display request by obtaining the requested graphic page from the graphics database and associated graphics functions from the video library.

Abstract: A method of predicting performance characteristics of an aircraft including modeling thrust-minus-drag of an aircraft with at least one mathematical model using aircraft specific data and input parameters which define the performance characteristics. Coefficients of the at least one mathematical model are learned over at least one flight. The performance characteristics are predicted as a function of the learned coefficients representative of a combined and non-independent thrust-minus-drag relationship.

Abstract: A feedback control system which uses estimated back electromotive force(EMF) from a controlled actuator to provide feedback into the control system and improve control of the actuator. Back EMF is estimated from current through the actuator and voltage across the actuator. The estimated back EMF signal is fed back into the control system where it serves as a rate term. In the preferred embodiment the back EMF signal is used in combination with an actuator position signal which is also feedback into the control system. A complementary filter conditions both the rate and position signals for improved performance. The invention is particularly suited for controlling linear actuators which do not provide conventional rate feedback signals.