Abstract: An apparatus for generating phase modulated angular positional signals in digital form. A phase tracking loop receives a phase modulated signal from the rotor of a resolver whose stator windings are excited in quadrature. The phase output of the resolver is proportional to the angular displacement of the rotor. Signals for exciting the stator windings of the resolver are applied in phase quadrature to a phase detector to develop an analog error signal when combined with the rotor output signal. The analog phase error signal provides an output indicative of the angular displacement of the rotor. The error signal is applied to a voltage controlled oscillator, converted to digital form, and combined with the excitation signals in a closed loop to force the error signal to a null, whereupon the indicated digital output angle is in coincidence with the angular displacement of the rotor shaft.

Abstract: A digital phase-locked loop provides substantially real-time measurements of frequency differences between an applied input signal and a reference signal. The system is especially adapted for the measurement of Doppler frequency shift in a Doppler sonar detection system. A two phase clock receives a reference signal and generates complementary clock signals. A phase-frequency detector receives an applied input signal containing a frequency shift and a further reference signal derived and applied in closed loop fashion. Frequency and phase discrepancies between the applied input signal and a second reference signal are gated to a counter to increment the frequency count or blank the frequency count for a predetermined period, thereby to synchronize the second reference signal with the applied input signal in frequency and phase.

Abstract: A flight director command indicator for a cathode ray tube display has a single cue positioned in roll, pitch and translation by combining roll attitude and pitch attitude command signals. It includes cooperating indicia for providing visual commands to bring the aircraft to a predetermined flight path of attitude to satisfy the flight director command.

Abstract: A contour line generator for identifying and displaying real time elevation contour lines for use with a moving map display. A plurality of data points neighboring a selected data point are compared to determine the presence or absence of a contour line. An average elevation is computed and applied to address a contour memory, having stored therein the elevations at which contour lines are desired to be displayed. The resultant logic signals are applied dynamically to override normal display data when a contour line is to be generated. The system provides programability for flexibility in modifying contour line intervals.

Abstract: A synchronous counter operating from a fixed frequency time base senses the data rate of an incoming bit stream and provides a time base synchronized with the incoming data. Detection of the data rate is accomplished in real time without software or user intervention. A two-stage counter, clocked by a crystal oscillator, is triggered by transitions of bi-phase data pulses. The circuit automatically shifts the frequency of operation to conform to the incoming data rate and returns to the high speed mode upon the cessation of low speed data rates.

Abstract: An improved apparatus for automatic deceleration of a helicopter to substantially zero air speed from a glide slope descent. Parameters available in a typical helicopter automatic flight control system, such as vertical speed, glide slope error, longitudinal acceleration, and pitch attitude are blended together in a manner as to approximate helicopter ground speed which is then used in a control law computation to decelerate the helicopter to a near hover speed as the vehicle approaches a preset altitude minimum.

Abstract: Method and apparatus for commanding an optimal flight path for an aircraft encountering a windshear condition. An airspeed rate signal equal in magnitude and opposite in sense to the windshear is applied to derive a variable rate of change of airspeed command for application to a flight director indicator. Limits are placed on the derived command such that the minimum allowable speed command is stick shaker speed and the maximum allowable speed command is the nominal speed in the absence of the windshear. The resultant command signal represents a true airspeed rate that yields an optimal flight path for the aircraft to exit the windshear condition.

Abstract: A dynamically reconfigurable array logic (DRAL) is capable of in-system logical reconfiguration in real time and comprises a RAM programmable logic array of bits, each bit comprising a fuse connection between logic elements. I/O means are coupled to the RAM programmable logic array for logical selection of registered output. A first register is coupled for receiving data and high-level commands. A sequencer includes a pair of up/down counters and functions to generate addresses. A timing device controls DMA transfers and issues READ and WRITE strobes. A second register monitors outputs and functions as a comparator, in a first mode, and functions to load outputs during specified time intervals in a second mode.

Abstract: A circuit for regulating the output of a DC power supply that substantially eliminates turn-on transients induced by the switching of a silicon-controlled rectifier (SCR). A zero-crossover detector senses the AC voltage waveform of an applied power source and provides a trigger signal at the zero-crossing point. The trigger signal is applied to cause induction of the SCR's and raise the output voltage when the power supply output drops below a regulated value, and is interrupted so as to inhibit conduction of the SCR's and decrease the output voltage when the power supply output exceeds the regulated value.

Abstract: A remote indicator for displaying the position of a power control switch whether or not power is applied to the switch. An auxiliary DC power supply provides a reference potential to a plurality of voltage dividers. One voltage divider provides a first reference potential to a comparator. A second voltage divider and the reference power supply are connected through the power control switch so that a second reference potential is applied to the comparator when the power switch is closed. Differences of the two reference potentials corresponding to the open and closed switch positions are sensed by the comparator and used to activate an indicator accordingly.

Abstract: A synchronous decoder for recovering a train of binary data encoded in a biphase format and decoding into NRZ format. Encoded data is sampled during the first half of a bit period and the second half of a bit period and stored respectively into two storage elements. The stored data is combined and applied to a third storage element at the beginning of the next bit period. The state of the third storage element is responsive to the sequentially applied combined signals in the train of data and thereby produces a pulsed output encoded in NRZ format.

Abstract: An integrated-optic waveguide apparatus uses a photoelastic substrate for sensing temperature changes. Optical channels are formed in a photoelastic crystal substrate by depositing film stripes thereon to cause stress-induced changes in the relative refractive index responsive to changes in the substrate temperature. Absorption and coupling or switching of light waves between the channels provides a variable light intensity as a function of temperature. A single-mode temperature sensor of the interferometer type provides high sensitivity without requiring a secondary reference light source. Multimode temperature sensors are also described which exhibit a wide dynamic range useful up to several hundred degrees C. at a slight compromise in sensitivity.

Abstract: A transformer for coupling electrical power from a stationary location to a moving location with a minimum of disturbance forces between the stationary and moveable components. The transformer is particularly adapted to coupling power to a magnetically suspended platform. The transformer includes an enclosed core housing two windings, a stationary primary coil, and a secondary coil free to move linearly and angularly over a limited displacement, where the secondary coil is affixed to the moveable platform, thereby enabling energy to be extracted for powering apparatus mounted within the platform.

Abstract: A servo system simulator utilizing an electronic equivalent of the servomotor to drive a programmable electronic load which mimics the actual load encountered by the servo system simulated.

Abstract: A ball structure for stabilizing bearing torque in high speed, preloaded, angular contact load supporting ball bearings operating on elastohydrodynamic lubricant films. Angular momentum developed about a ball spin axis that is not parallel to the bearing rotation axis results in a continuous creep of the ball about the momentum axis, thereby allowing a long term preload and torque variation. The improved ball set is shaped so that each ball has a mass inertia about its desired spin axis that is greater than about all other axes, so as to develop a restoring moment tending to maintain rotation about a fixed axis in each ball. The ball cage is configured to maintain ball alignment during run-up and run-down of the bearing.

Abstract: The invention provides for rapid response and reliable detection of vertical windshear during the takeoff and approach phases of flight. Standard instrumentation available on many aircraft is used to calculate the down-draft acceleration and its effect on the aircraft's performance capability. The invention utilizes inputs from vertical acceleration, true airspeed, pitch angle, and angle of attack sensors. The rate of change of vertical wind is derived from the sensed signals and used to determine the margin between the aircraft's present performance capability and the predicted performance capability at stick shaker speed.

Abstract: A cathode ray beam deflection system operable in slew and random stroke and periodic raster display modes provides automatic power supply voltage switching to maintain linear operation and high efficiency. Control of automatic switching is obtained by continuously monitoring yoke voltage, yoke current, and deflection voltage, a power supply voltage being switched to a voltage of higher magnitude to provide a higher deflection rate when the yoke voltage exceeds a predetermined level at a predetermined current polarity and returned to a power supply voltage of lower magnitude when the higher deflection rate is no longer required.

Abstract: Apparatus for the automatically controlling aircraft descent to a computed descent flight path. At any point in the descent portion of flight, a path error signal is used to compute an incremental speed command that is algebraically summed with a nominal descent speed command to cause the aircraft to converge to or maintain the computed descent path. Means are provided to rate limit the algebraic addition of the incremental speed command so that the convergence rate to the path is virtually constant for a given path error and so that the relatively short term dynamics of accelerating and decelerating the aircraft which may cause oscillatory behavior are avoided. The use of an incremental speed command permits a simplified control law over the prior art and permits the direct control of the minimum and maximum allowable speeds of the aircraft without the necessity of switching control laws or additional monitoring.

Abstract: A digital hysteresis circuit which generates a stable signal for driving a digital readout indicator from an analog signal indicative of the position of a mechanical driving device having noise signal components leading to erratic indications superposed thereon.A reference signal generated by an up-down counter is compared with the digitized input signal in a memory store. Only when the difference in the compared digital values exceeds a predetermined digital hysteresis value in the memory store corresponding to the allowable noise signals is a command signal generated to increment or decrement the counter so as to reduce the difference in digital value. The reference signal is applied to drive the digital readout indicator, thereby precluding unstable indications due to noise, jitter, and system threshold uncertainty.

Abstract: An electron beam magnetic deflection system capable of raster and stroke deflection and providing minimum power dissipation in raster mode. Automatic switching of the voltage demanded in raster mode is obtained by continuously sampling the yoke current, the power supply voltage being switched in magnitude and polarity corresponding to the direction of change and polarity of the yoke current. By returning energy stored in the yoke to the power supply during portions of the raster cycle, power efficiency is substantially enhanced.