Abstract: A low cost, simple to manufacture, two axis gyro having an outer flexure assembly and an inner flexure assembly. Each flexure assembly contains two flexure hinges which represent a reduction in the number of hinges and milled cuts from those required in prior art devices. The inner flexure assembly is designed to nest within the outer flexure assembly and both are mounted centrally on a rotatable shaft for rotation about the gyro spin axis. The two flexures of the outer assemblies are separated 180.degree. from each other and adjacent to two slots also separated by 180.degree. in the rim of the outer gimbal. Likewise, the two flexures of the inner flexure assembly are separated 180.degree. from each other and 90.degree. from each of the outer flexures. The outer flexure assembly axis is offset axially by a controlled amount from the inner flexure assembly axis to achieve nominal balance on both flexure axes.

Abstract: In a ring laser gyroscope having a triangular optical resonator with mirrors at its corners, in order to prevent lock-in, a portion of the light from the beams that passes through the mirrors at the corners is fed back into the clockwise and counter-clockwise beams after being passed through an optical resonator containing a nonreciprocal phase shifter.

Abstract: The power switch driver circuit of a brushless DC motor control ensures synchronous operation by utilizing a ROM addressed by motor shaft position sensors. Excess current drawn by the motor windings is sensed by a detector which provides an additional bit of address input to correct the condition. The address input may also be modified by a bit signifying forward or reverse operation of the motor.

Abstract: A solid state synchro torque receiver driver that uses unfiltered AC as the power source and push-pull regulating transistors operating in the linear mode to drive the torque receiver stator loads. A feedback amplifier compares the push-pull outputted AC signal against an inputted AC data reference (i.e. the desired stator excitation amplitude) and thus closes the loop forcing the output to follow the input. The synchro torque receiver operates in a closed loop and thus has realizable potential of near infinite resolution and high accuracy.

Abstract: An improved input system for isolating resolver or synchro outputs from inputs to demodulators or analog-to-digital converters uses current transformers rather than voltage transformers. The resistances of resistors connected in series with the primary windings of the isolation transformers are adjusted to standardize the input currents of the transformers.

Abstract: A gyroscope with a solid rotor synchronous motor having three-phase square wave supply voltage is provided, and control circuitry including logic circuit components for periodically producing an amplitude modulation in the motor excitation voltage of constant frequency that results in a periodic slipping of a few degrees of the solid rotor relative to the electrical field is provided, whereby gyro drift errors varying sinusoidally in sense and magnitude in accordance with the relative rotation between field and rotor, balance out during each complete cycle of relative rotation.

Abstract: A method and apparatus for pre-setting the position of a piezoelectric actuator used in controlling the path length of the laser beam of a ring laser gyroscope is disclosed. The path length controller of this invention minimizes the necessary rectilinear motion of the actuator by presetting the actuator position according to the environmental or start-up temperature of the ring laser gyroscope to anticipate changes in the laser path length resulting from changes in the environmental temperature and/or self heating effect when the gyroscope is in operation.

Abstract: The invention comprises a novel strapdown gyro inertial system having a single degree of freedom between it and the vehicle upon which it is mounted. An angular transducer having a low friction bearing is mounted on the vehicle along the vehicle roll axis bearing and supports the strapdown gyros and accelerometers that are skewed with respect to the roll axis. The method of determining the total vehicle attitude employs the gyros so that the vehicle rate around each gyro axis is integrated and combined with the vehicle angular roll to obtain the total attitude. The inertial momentum of the sensor block, electrically enhanced or strictly dependent upon its mass, decouples high acceleration inputs along the free axis and thus reduces the dynamic rate sensing requirement along the free axis. Also the novel configuration of the sensors skewed with respect to the free axis, permits easy calibration of gyro scale factors and other inertial parameters which are characteristics of gyroscopes and accelerometers.

Abstract: An anode for a ring laser gyroscope which provides improved current stability in the glow discharge path is disclosed. The anode of this invention permits operation at lower currents thereby allowing a reduction of heat dissipation in the ring laser gyroscope. The anode of one embodiment of this invention is characterized by a thumbtack appearance with a spherical end where the normal sharp end of the thumbtack would be located. The stem of the anode extends from the outside of the gyroscope structure to the interior of the structure such that the spherical end is substantially adjacent to the laser beam.

Abstract: A receiver is provided for use in a fiber optic data communication system of the type employing unipolar trapezoidal Manchester data encoding. The receiver of the invention is capable of processing unipolar optical Manchester signals transmitted over optical fibers. The receiver converts the optical signals into electrical base-band signals, and then amplifies, filters and detects the electrical signals to provide standard digital levels at the receiver output. The receiver incorporates direct-current coupled amplifiers, fast automatic gain control circuitry for the amplifiers, direct current offset correction circuitry to prevent drift of the signal base line, and threshold circuitry controlled to assure half peak amplitude, or mid-amplitude, processing of the electrical signals.

Abstract: A dry tuned two axis gyro having a pulse-rebalanced rate capture loop control. This configuration eliminates the need for an analogue-to-digital converter since the gyro is torquered at a pulse rate using a constant current source. Another feature of the control loop is a cross-channel shaping network which exchanges an electronically damped error from one axis to the other axis. By means of a summing network which combines the error signals from the main channel and the cross channel with a source of time varying ramp voltage, an alternately negative to positive signal is applied to the gyro torquer.

Abstract: A system for cancelling lock-in in a spring suspended ring laser gyroscope by dithering it at a rate which is a function of measured optical phase and dither rate.

Abstract: In order to provide high accuracy shaft angle to linear DC voltage conversion using low accuracy devices, a linear synchro is excited by a 2.5 KHZ square wave which is power buffered, the square wave also used to synchronously demodulate the output of the wound component by sampling and a demodulated voltage then filtered and scaled to the required levels using commonly available operational amplifiers.

Abstract: In a ring laser gyroscope which has a triangular block configuration, and which incorporates a triangular shaped laser resonant cavity defined by three corner mirrors, including an output mirror, the gyroscope is sinusoidally dithered to reduce lock-in effects at low angular rotational rates and the gyroscope output is corrected for error caused by lock-in at the extremities of each oscillation when the dither velocity is equal to zero by accumulating the ac voltage outputs of a photodiode measuring the light intensity of the interference pattern at each zero dither velocity and when the accumulated phase error reaches 2.pi. an overflow or borrow pulse is generated and added to the normal gyroscope output thereby correcting for the accumulated errors caused by lock-in at zero dither velocity.

Abstract: A system for offsetting lock-in in a spring-suspended ring laser gyroscope by dithering it by means of a torquer whose input is controlled by the sum of an analog positive-feedback signal for cancelling out losses due to damping and a piecewise-constant signal for adjusting the effective dither angular velocity phase in each cycle.

Abstract: The adaptation of a heat pipe as a turbo-generator or other power output device for a reliable, quiet, light-weight high-endurance power source is shown. The device requires input thermal energy from a burner radioisotope (or solar heat) and also forced or natural heat rejection from condenser surfaces. Thermal energy conversion to a suitable power output is accomplished by encapsulating a turbine wheel within a heat pipe shell, located in an appropriately geometrical contoured section. Flow work extracted from the kinetic energy of the vapor flow provides rotary shaft power output. The shaft power can drive an electrical generator, pump, compressor, or similar device, also mounted within the heat pipe shell structure. A completely self-contained enclosed unit is provided which requires only external power connection at attachment terminals.

Abstract: In order to more efficiently transmit optical data on an optical data bus to a number of members of an optical data transmission community, an electronic active star element which receives signals from each of a plurality of remote terminals, converts the optical signals to electrical signals, amplifies them, and transmits them to the remaining remote terminals is provided.

Abstract: In order to correct errors in a synchro control transmitter, the error in the transmitter is measured at equal angular increments, the magnitude and phase of the maximum error of the second harmonic determined and resistors placed across two pairs of the three transmitter outputs selected such as to establish a second harmonic load unbalance which is approximately equal in magnitude and opposite in phase to the measured error.

Abstract: In order to provide a system for measuring relative velocity of a surface with the accuracy of a laser velocimeter but avoiding the problems associated with operating down to zero speed and with signal dropout during a run, a tachometer is coupled to measure the relative velocity and the output of the tachometer corrected using the output of the laser velocimeter thereby giving laser velocimeter accuracy over the major portion of the velocity range but still permitting operation down to zero speed and operation when signal dropout occurs.

Abstract: In order to provide improved performance in a printed antenna, particularly for use in a Doppler navigation system, two pairs of linear arrays slanted at 45.degree. are utilized to obtain a beam shape which exhibits a degree of independence from over-water shift with the two sets of arrays constructed respectively as forward and backward firing arrays in order to compensate for frequency changes.