Abstract: A drive circuit for servomotors that eliminates the need for microswitches to protect the motor when the system is driven to its limits of travel. The circuit monitors the current to the motor, identifies overload currents and terminates current flow to the motor when an overload occurs. The current flow is restored only when a reverse rotation command signal is received by the drive circuit.

Abstract: A method and apparatus for performing high speed graphics fill is provided. Any closed line geometric shape or polygon that can be defined by pixel position is stored in memory. The memory pixel positions are stored in address locations corresponding to row and column positions. A first sequential examination of the data is made in reverse raster scan order to make a preliminary determination of the pixel positions inside the closed polygon. A second sequential examination of the data is made in forward or regular raster scan order and a final determination is made whether the pixel positions are inside the polygon and shall be filled. The final determination of pixel positions to be filled is stored shortly before the graphics fill operation is performed so that the fill operation is performed in raster scan time at high speed.

Abstract: A controller for maintaining a motor operation at a desired rotational speed utilizes a phase locked loop that receives input signals from a tachometer coupled to the motor shaft. Reference frequencies for the phase locked loop are generated by a voltage control oscillator in response to voltages selected in accordance with the desired motor speed. These selected voltages are coupled to the motor speed control to establish a motor speed within the lock-in range of the phase locked loop. Tachometric feedback is applied in parallel for the phase locked loop. The open loop drive provided by the selected voltage guarantees degraded open loop control of the motor should the control circuit fall.

Abstract: A synthesizer circuit which generates a family of independent clock signals from multiple input clock signal sources under microprocessor control.

Abstract: Apparatus for providing precise convergence measurements of electron beams in a CRT display by sensing the displacement of brightness peaks as an array of phosphorescent regions are sequentially illuminated by energy from the electron beams deflected by the deflection apparatus of the display system and an independent external time varying magnetic field applied by enclosing the CRT housing within a pair of external coils. Convergence is calculated by calibrating the recorded brightness peaks as a function of beam displacement. The system is adaptable to measuring both vertical and horizontal components of convergence as well as linewidth. The apparatus operates independently of and does not require interruption of dynamic functions which operate in synchronism with the deflection circuits, such as dynamic convergence correction.

Abstract: A differential capacitance detector comprising two pulse generators and a comparator. The width of each pulse generator output is representative of the capacity of each of two capacitors whose differential is to be determined. A comparator provides a third pulse whose width is the difference of the width of the pulses input from the pulse generators and is representative of the capacitance differential between the two capacitors.

Abstract: A magnetic actuator for providing a single-axis, noncontacting force capability with unconstrained cross-axis mobility utilizes flux feedback force linearization. Electromagnets cooperating with an armature suspended therebetween are energized by a bias flux and a signal derived from flux densities sensed in the air gaps. The bias flux density may be optimized to minimize the peak power required by the actuator. The flux density signals are applied in a closed force loop to provide a net force directly proportional to the commanded flux.

Abstract: A cruise speed control apparatus for aircraft wherein small differences between the target Mach command and the actual Mach number of the aircraft are used to displace the aircraft from its reference altitude to either increase or decrease actual Mach number in the short term. Long term differences are corrected through a special isolation filter to separate the engine control loop and pitch control loop dynamics and an integration technique to adjust the automatic throttles about a thrust target for the commanded Mach.Large differences between the target Mach and the actual Mach or large changes in the commanded Mach are compensated for by a non-linear gain that effectively increases or decreases the target thrust to cause the aircraft to accelerate or decelerate to the commanded Mach.

Abstract: A digital signal detector utilizing a detected input digital signal derived from a reference square wave and a received pulse train to establish phase and frequency variations between the reference signal and the received signal. The detected signal and the reference signal are coupled to up-down counters wherein overflow counts from preset values are obtained which are representative of the frequency and phase difference between the reference and received signals. These overflow counts are utilized to establish phase and frequency error correction signals which may be coupled to control the reference oscillator to provide frequency and phase lock between the reference and received signals.

Abstract: A plurality of concentric sealing rings on the face of a static sealing surface provides a positive seal when used with Teflon film or like materials that have a tendency to cold flow under pressure into recesses created by the concentric sealing rings.

Abstract: A low noise amplifier (LNA) circuit including a linear amplifier which generates low noise in the presence of a high level signal and includes a field effect transistor with input and output matching networks and which retains linear operation in the presence of high level (high magnitude) interfering signals.

Abstract: A power density spectrum controller circuit which incorporates a programming element in conjunction with a voltage controlled oscillator and which uses spread spectrum techniques to provide a relatively clean output signal having little or no ripple, little or no noise and little or no signature while having a minimum output filtering requirement.

Abstract: A system for the secure and rapid acquisition of a transmitted acquisition composite code composed from acquisition component codes. The acquisition composite code may, for example, be composed in accordance with a Boolean majority voting rule. Reference component codes that correlate respectively with the acquisition component codes are combined to provide a verification composite code that correlates with the acquisition composite code only when all of the reference component codes in the verification code are each in alignment with the corresponding acquisition component codes in the acquisition composite code. The verification code may, for example, be composed in accordance with a modulo-2 addition rule. Initially, the reference component codes are individually brought into alignment with the transmitted signal during the acquisition thereof.

Abstract: An apparatus for providing asymmetrical torque-switching for an aircraft autopilot. The invention provides an increased amount of available pitch servo torque at high altitude. The direction of pitch of the aircraft is sensed. An increased amount of torque is provided for the pitch-up direction thereby providing more positive control of the aircraft.

Abstract: Adaptive filters are used to separate frequency hop signals to improve the detection and estimation of the frequency hop signals. In preferred embodiments, two or more adaptive filters (which can be connected in series or in parallel) exhibit different convergence characteristics to isolate a frequency hop signal.

Abstract: This invention is directed to a spectrum analyzer system which is laser-driven and which includes a standard Bragg cell and a standard photo-diode array as the output detector. In this system, the Bragg cell is driven by a bandwidth expansion circuit which receives the typical R.F. input signal, supplies it to a variable center frequency filter or to a bank of filters which then down-converts the signal and supplies the signal to a real time signal storage memory at a first signal rate. The signals are retrieved from the memory at a second, much greater signal rate, up-converted and supplied to the Bragg cell to affect the operation thereof in the usual fashion. This time base compression circuit has the effect of producing an improved optical spectrum analyzer with expanded frequency resolution.

Abstract: A battery powered optical sensor, capable of functioning for a period of time approximately equal to the shelf life of the battery, utilizes an LED driven by an optical transducer and biased by the battery at a level that exceeds the shot noise level of the LED by the dynamic range of the sensor.

Abstract: A variable coupler fiberoptic sensor in which a fused, tapered, biconical directional fiberoptic coupler is encapsulated in a stress birefringent medium whose index of refraction changes with applied stress.The ratio of power in the output fibers of the directional coupler varies with the change of index of refraction of the encapsulating medium as stress is applied to the medium.

Abstract: A cathode ray tube provides a raster can symbol display superimposed on a stroke vector display, with selected regions of the stroke vector display preferentially masked in response to priority instructions. Stroke vector priority data is loaded into a full-field bit-mapped memory by a raster symbol generator and used to provide a stroke vector masking signal in synchronism with the picture elements of the raster scan. The system provides efficient generation of dynamic stroke priority areas by utilizing the repetitive nature of the raster scan to load the stroke priority full-field bit-mapped memory without requiring corresponding processor intervention.

Abstract: A dispersive Surface Wave Acoustic (SAW) filter is provided by a dispersive reflective array, and input and output transducers that we aligned with respect to the array so that the angle of incidence of a SAW from the input transducer is approximately equal to the angle of reflection from the reflective array over the entire range of the dispersive array, wherein the transducers are constructed to provide a frequency response which is matched to the periodicity of the dispersive array. Such design may be accomplished by forming the transducers with hyperbolically curved electrode fingers. The transducers may consist of relatively narrower inner electrode fingers and relatively wider outer electrode fingers. The transducers may also be divided into a plurality of tracks with each of the tracks being subdivided into a plurality of subtransducer elements which are capacitively coupled in electrical series.