Abstract: A control system using a duty cycle converter to convert an analog input into both a second order or velocity squared feedback as well as a set of clockwise and counterclockwise pulse trains the frequency of which is dependent upon the amplitude of the input signal. The velocity squared feedback is augmented by a position feedback from a stepper motor to provide optimum operation. To obtain optimum performance from a stepper motor, the rate of change of input pulses must not exceed a predetermined value for starting or stopping or the motor will react improperly to some of the pulses. The present system provides a linear increase in the step rate to a maximum and then a linear decrease in the step rate such that there is no overshoot beyond the requested analog input signal.

Abstract: An incremental type shaft position encoder which provides a distinguishable signal at each of a plurality of predetermined shaft rotational positions, and which further provides a unique electrical signature associated with each of predetermined ones of the signals.

Abstract: Gasket material which is curved in cross-sectional shape. The curved section is placed between mating flanges situated around an opening such as an RF conduit. The radius of curvature is such that the modulus of elasticity is not exceeded upon compression of the flanges and thus the gasket is reusable while providing maximum contact pressure on the mating surfaces for sealing purposes. The curved contact area is offset from any openings in the flange for the passage of fastening means that provides the compressive action. This offset of the maximum pressure contact areas from openings increases the sealing capability of the gasket.

Abstract: In a mechanical filter, a ferrite transducer rod is attached to a disk resonator by bonding with an adhesive which is deposited in an annular housing affixed to the disk prior to inserting the transducer rod therein.

Abstract: A circuit for detecting and synchronizing an incoming signal to a reference clock wherein the incoming signal has a slightly lower frequency and may be variable in frequency with respect to the reference clock frequency. The output from this synchronizer will be stable during the first half-cycle of the reference clock and may vary during the second half-cycle of the reference clock.

Abstract: A non-linear output signal is generated from an input signal by multiplying the input signal with a feedback signal which is directly proportional to the difference between the output signal and some signal threshold level whenever the output signal is in one region with respect to the signal threshold level and zero whenever the output signal is in the other region.

Abstract: Method and apparatus for controlling aircraft flight control surfaces. A signal indicative of control surface movement rate is provided and tested for level and duration. When said rate indicative signal exceeds a predetermined level for a predetermined time, authority of positioning apparatus over the aircraft control surface is reduced.

Abstract: An optical transducer encoding system for use with mechanical counting means such as intermittent movement type counting mechanisms is illustrated using a stationary support means thereof as a housing for a plurality of transducers which transmit light to reflective means on the web of each one of a plurality indicia wheels and which light is reflected to optical sensors within the stationary support. All the reflective means are at the same radial distance from the hub of the wheel and the transducers provide an encoded electrical output indicative of the indicia readout.

Abstract: A temperature compensated constant voltage circuit utilizing a constant current supply circuit having a positive temperature coefficient of current for supplying current to a nearly constant voltage dropping circuit. The voltage dropping circuit includes a zener diode which has a negative temperature coefficient. The combination of the positive and negative coefficients cooperate to produce a temperature stable constant voltage circuit.

Abstract: The outputs of two like frequency oscillators are combined to form a single reliable clock signal, with one oscillator functioning as a slave under the control of the other to achieve phase coincidence when the master is operative and in a free-running mode when the master is inoperative so that failure of either oscillator produces no effect on the clock signal.

Abstract: A fast-attack circuit is employed in an A.C. amplifier automatic gain control circuit to temporarily apply a D.C. gain control signal immediately to the amplifier circuit in response to a sudden signal increase in excess of a predetermined threshold level to avoid the problems of over-attack and pinch-down which might otherwise arise during the period required for the AGC loop to achieve stabilized control following the inception of the signal increase.

Abstract: A digital circuit for generating an error correction or otherwise characterized signal having a value which changes in accordance with a second signal such as the speed of an airplane (MACH). As a specific example, the generated signal is indicative of the error correction required to the static and derived pilot tube pressure signals which error correction changes non-linearly with respect to the velocity of the airplane. Since, in general, each type of airplane requires its own special correction signal, the apparatus must be readily alterable to a given specific application.

Abstract: A system for generating respective X and Y beam deflection command signals as respective running binary counts in X and Y deflection counters utilizing digital computations based on the straight line expressions Y=X tan .alpha., where .alpha. is the line slope. Relative clock rates are defined by the tan .alpha. relationship therebetween, and, by defining a line as lying in one of eight 45.degree. octants, and a circle as successive points of tangency of a plurality of lines tangent to the circle comprising circumferential segments in eight contiguous ones of the octants, the system effects generation of respective X and Y counts to trace a line of selected length and slope as well as a circle of selected radius utilizing but a single table of tangents for angles between 0.degree. and 45.degree. as the required data storage.

Abstract: The circuitry illustrated utilizes duty cycle conversion means for providing signals indicative of Sin and Cos of an angle .theta. as well as the derivative of Sin.theta. and Cos.theta.. The derivative signals are then duty cycle multiplied by the Sin.theta. and Cos.theta. signals and the products are summed to provide an output d.theta./dt which is indicative of angular rate of change.

Abstract: An electromagnetic wave guiding rotary joint admitting of rotary motion about two or more axes. A spherical journal and a complementary spherical race afford electromagnetic communication between two wave guiding means.

Abstract: Rate of change of the angle .theta. conveyed by a three-wire synchro signal is developed as an inherently normalized signal (d.theta./dt) by dividing N sin .theta. (d.theta./dt) signals by N sin .theta. signals and N cos .theta. (d.theta./dt) signals by N cos .theta. signals over selected ones of contiguous segments of a full 360.degree. range of .theta. where the divisor signals do not go through zero. The N sin .theta. and N cos .theta. signals are normalized outputs of dividers which divide synchro carrier reference demodulated sin .theta. and cos .theta. signals by a synchro carrier reference level signal. N sin .theta. and N cos .theta. signals are differentiated to derive the N sin (d.theta./dt) and N cos .theta. (d.theta./dt) signals. Logic circuitry switches appropriately signed ones of the signals as divisor and dividend inputs to an output divider whose output is (d.theta.

Abstract: A series current limiting circuit for intermittent current flow when the current exceeds a predetermined limit. A time delay circuit is incorporated to maintain the interrupted condition for a predetermined additional time after initial interruption before returning the circuit to an ON state whereby it can be determined if the conditions causing overload have been removed.

Abstract: The detection of frequency tones, such as used in telephone pushbutton dialing to identify the digits of a called number, is performed in a digital manner which affords both speed and reliability of detection, by repetitively measuring the frequency of a frequency tone so that each measured frequency can be assigned to one of a plurality of valid frequency bands, maintaining a count thereof for the individual frequency bands, and assigning the frequency tone to the first frequency band to achieve a predetermined count level.

Abstract: Ground closure rate between an aircraft and underlying terrain is obtained by differentially combining a radio altimeter derived rate signal and a barometric altitude rate signal to obtain a rate of change of ground profile signal. The ground profile rate is filtered on an autocorrelation basis to obtain a profile rate signal devoid of amplitude pulses introduced by sharp or discontinuous terrain features and recombined with barometric rate to obtain ground closure rate. The filtering technique imposes no rate limitation on the radio rate signal.

Abstract: A phase lock loop incorporating a novel feedback arrangement to provide an output of the same frequency as an input reference and phase shifted therefrom by a settable amount. The feedback portion of the phase lock loop from the output of the voltage controlled oscillator to the second input of a phase detector comprises a cycling digital counter and a coincidence detector which detects coincidence between the count of the counter and a set or programmable input. Whenever coincidence occurs, an output signal is provided to the phase detector such that the VCO is adjusted to provide the proper phase relationship between the input and the output signal.