Abstract: A pneumatically dithered ring laser gyroscope features providing an oscillatory motion directly to a segment of the excited gas which serves as the laser photon source. Alternately switching ionizing potential between two cathodes in appropriately designed cavities establishes desired oscillatory gas velocities to effect emitted frequencies within the gyro, thereby permitting the detection of rotational rates below the "lock-in" rate of the undithered gyro.

Abstract: To determine the angular orientation of polarization axes within a length of polarization-maintaining optical fiber, a coherent light source, such as a laser, is focused onto the side of the polarization-maintaining optical fiber and a resultant scattered pattern is generated. A sensor/analyzer monitors the resultant scattered pattern and determines the location of the polarization axes.

Abstract: Radar data vectors of a desired number of pixels in length are scan converted, at a desired angular rate. A complete 360 degree radar data scan is maintained in memory. A raster image of a desired number of pixels in size and of arbitrary position and angular orientation with respect to the radar scan in memory is outputted. The resolution of the raster output image is varied to adjust its update rate. A high resolution, motion stabilizing radar display is provided and a multiresolution capability is available to eliminate image artifacts attributed to raster image update rate.

Abstract: A two degree of freedom gyroscope having a drive motor (20), with a permanent magnet rotor (22), which includes an optical sensor (11) for providing an X-axis signal and a Y-axis signal which are indicative of the displacement of the actual rotor (22) spin axis from the null spin axis (28), a torquer coil (26) looped around the permanent magnet rotor (22) and disposed in a plane orthogonal to the null spin axis, and torquer drive elements (52, 54, 56) responsive to the X-axis and Y-axis signals induced in the sensor when the actual rotor (22) spin axis is displaced from the null spin axis (28) for providing current to said torquer coil (26) to urge the axes to coincide.

Abstract: A two-sided hermetically sealed package of a metal matrix composite material includes a heat sink and integral cooling fins on each of the two sides which are totally enclosed to retain cooling fluid. Power semiconductors are mounted on ceramic substrates having metallic conductors mounted on both sides thereof. The substrates are mounted to the heat sinks. Cooling is provided by the passage of cooling fluid into one end of the enclosed fins, over the fins and out the other end. The metal matrix composite material and the ceramic are thermally matched and the package is provided with a minimum number of thermal interfaces.

Abstract: A stable output, widely dimmable light source (20) utilizing a gas discharge lamp (14) including an external igniter (12) which is utilized to provide lamp ignition at approximately the same time as an AC potential source (22) provides power to the lamp (14) cathodes. A high voltage pulse is applied to the external igniter (12) causing ionization of the lamp gasses at the start of each time period during which the ballasted AC potential source (22) is applied to the lamp (14). Average light output level is controlled by a light output selector (36) which controls lamp on time and thus the average light output of the lamp (44). During operation lamp (14) is turned on several times per second, such as sixty-eight and the AC potential source (22) has a relatively high frequency, such as 45 KHz.

Abstract: Sensitivity time control (STC) data for an airborne weather radar system is provided as a function of aircraft altitude and radar system antenna tilt angle to normalize radar return signals at high as well as low aircraft altitudes. In one form of the invention the STC data is used to adjust the gain of a signal applied to a radar system received by a system antenna and in another form of the invention the STC data is used to establish a desired threshold for said signal.

Abstract: A closed loop fiber optic gyro features signal processing wherein square wave phase modulation is added to a modulation drive signal after overflow logic so that the square wave modulation will not cause a phase modulation ramp to exceed overflow/underflow logic limits. The arrangement is such that the phase modulation causes a retrace with each modulation period when the amplitude of the ramp is within predetermined limits. A variable time constant in a retrace correction loop gives better retrace limit correction performance when the gyro is first turned on as during a "warm-up" period. The amplitude of the gyro square wave output is determined by taking the difference between the output of the first half cycle of the square wave modulation and the average of adjacent second half cycles thereof. An error signal for a retrace limit is developed by considering changes in the square wave amplitude and not the square wave amplitude itself.

Abstract: The accuracy of the performance of an inertial navigation system is validated by comparing data measured by a fourth gyro and accelerometer to an analytic equivalent constructed from measurements made by a primary gyro/accelerometer orthogonal triad.

Abstract: A method for synchronizing a distributed multiple clock system in which the first clock to reach a first predetermined number of counts generates a polling request signal. The remaining clocks compare the content of their counters to determine if they are in synchronization with the clock that generated the polling request signal. Each clock will place itself inactive if it determines it is out of synchronization with the active clocks. The first active clock to reach a second predetermined number of counts will generate a synchronization interrupt signal which resets a counter in each clock to zero. A start subroutine readmits inactive clocks when after a synchronization interrupt signal is generated its counts are within a predetermined readmittance range or its counter counts up to a third predetermined value.

Abstract: The signal that controls the gain of a sensitivity timing control (STC) circuit is slimmed with a gain correction signal to compensate for gain variations introduced by items such as variations in the parameters of electronic components. A known test signal is injected into the STC circuit and the resulting output signal is measured. The amplitude of the gain correction signal is determined based on the difference between the desired output signal amplitude and the measured output signal amplitude.

Abstract: A method for characterizing frequency modulation rate parameters for a swept frequency signal is based on zero crossing counting and digital signal processing. The method is easy to implement and does not require batch processing so as to be suitable for real time tracking of frequency variations in a variety of applications.

Abstract: A circuit wherein a current sensing device is incorporated in an AC input line. An AC output is taken from the output of said current sensing device and from an other AC input line. Circuitry including two bi-directional switching regulators (positive and negative) and two energy storage capacitors adds current to or subtracts current from the instantaneous output load current. The arrangement is such that the AC output is equal to the AC input with no regulation effect. Substantially one hundred percent efficiency results when very little power factor correction is required.

Abstract: Thermal imaging apparatus including a non-linear optomechanical scanner receiving light from a scene and directing it onto an image plane, the scanner defining a non-linear scan velocity in the image plane, a SPRITE detector disposed in the image plane and including first and second spaced contacts and apparatus for applying a bias voltage across said contacts, and apparatus for varying the bias voltage across the contacts as a function of the non-linear scan velocity, thereby to compensate for the non-linearity of the optomechanical scanner.

Abstract: Each towed field artillery piece in a battery of field artillery pieces uses a heading reference system having a "slave" azimuth gyro, pitch and roll angle sensors and a readout display for correcting azimuth and elevation during a fire mission. A master system includes a "master" azimuth gyro which is mechanically lined up with the axis of the "slave" azimuth gyros in the heading reference systems. The master system transfers azimuth information to the slave system, whereupon the slave system acts as a repeater for the information given by the master to confirm congruency of the master and slave systems and provides the present location of the respective field artillery pieces.

Abstract: A closed loop fiber optic gyro features signal processing wherein square wave phase modulation is added to a modulation drive signal after overflow logic so that the square wave modulation will not cause a phase modulation ramp to exceed overflow/underflow logic limits. The arrangement is such that the phase modulation causes a retrace with each modulation period when the amplitude of the ramp is within predetermined limits. Corrections to the retrace limit are implemented so as to scale a digital output, which enables the determination of accumulated gyro angle with a finer resolution than simple output pulse accumulation as has heretofore been the case.

Abstract: A closed loop fiber optic gyro features signal processing wherein square wave phase modulation is added to a modulation drive signal after overflow logic so that the square wave modulation will not cause a phase modulation ramp to exceed overflow/underflow logic limits. The arrangement is such that the phase modulation causes a retrace with each modulation period when the amplitude of the ramp is within predetermined limits. The square wave amplitude from a cycle immediately after a retrace is considered as errant data that should be excluded from a phase nulling loop. Thus, the phase nulling loop has more accurate input data so that feedback will be accomplished more effectively for improved gyro performance.

Abstract: The phase voltages of a three phase alternating current input voltage are converted into currents. The negative half-cycles of the currents are added and the polarity of the added current is reversed. The current at the reversed (positive) polarity is converted into a positive output voltage which is a measurement of the input voltage.

Abstract: A VHF radio (10) which includes an adjustable antenna (20) formed from a component (28) shaped like an open helical compression spring which engages and can be screwed into a metal supporting collar (40) for tuning the antenna (20). An elongated plastic or rubber cylindrical member (30) is connected to the metal collar and surrounds at least a portion of the helical member (28). An end cap (32) is provided for closing the other end of the cylindrical member (30).

Abstract: A digital video quantizer for use in TCAS and ATCRBS/SIF systems. A digital delay receives a digitized video signal and produces a plurality of delayed digital signals which are used throughout the quantizer. A threshold generator then produces a predetermined threshold and a dynamic threshold, and a quantized video generator compares one of the delayed digitized signals to a threshold to produce a quantized video signal. A slope quantizer detects a slope of the digitized signal which exceeds either a positive or negative threshold. In addition, a rise time detector detects an excessive rise time in the digitized video signal, and a chip amplitude comparator provides a signal which is used in detecting Mode S data bit values. The digital video quantizer's use of digital references rather than analog references, eliminates the inaccuracies caused by a reference voltage varying over time or temperature. The digital references also facilitate modification of the reference values at a later time.