Abstract: A light control device includes a bimorph element comprising two thin polyvinylidene fluoride films and a thin layer disposed therebetween to secure the films together. The bimorph element bends in accordance with an applied electric field to open or close an opening in a panel, thereby displaying a pattern, or to open or close a passageway of light, thereby performing a shutter operation.

Abstract: A dielectric-isolated PNP transistor with Schottky protection, either alone or as one of an integrated pair of complementary bipolar transistors has complete dielectric isolation from neighboring devices and from the substrate by means of a topside anisotropic etch. This leaves the devices in mesa form, thinner versions having the facility of lateral terminations, e.g. for the collector. The method is advantageously adapted to provide single type or complementary bipolars with integrated Schottky barrier protection.

Abstract: A layer of thermally deformable plastic used, for example, in a holographic recording medium has an undulated surface whereby the layer has an uneven thickness. Because of the uneven thickness, the layer has a composite spatial frequency pass band greater than the spatial frequency pass band of a layer of uniform thickness.

Abstract: A PNP bipolar transistor is protected by a Schottky barrier, in which an N- base of the device forms a Schottky diode with a metallizing which is used as the collector. No separate P- semiconductor region is provided as the collector. Such transistors may be combined with NPN transistors having integrated but distinct Schottky and collector electrodes.

Abstract: A shielded, floating ground RF input connector assembly is provided by a conductive enclosure having an aperture in one wall. A coaxial connector is mounted with both the inner and outer conductors extending through the aperture and with the outer conductor spaced from the aperture. A conductive flange extends radially from the outer conductor within the enclosure and covers the opening of the aperture with the flange closely spaced by a member of dielectric material from the inside wall of the enclosure. Bypass capacitors are connected between the conductive flange and the enclosure.

Abstract: A low cost microwave communication system is described in which a transmitter including an IMPATT diode operating CW (Continuous Wave) is amplitude modulated by a video signal such that the radiated RF (radio frequency) output from the transmitter is directly proportional to the amplitude of the video signal. Low level radiated power from the transmitter is picked up by a receiver which includes a "square law" detector. The detector provides an output voltage according to the power level of the received RF signal.

Abstract: For a spacecraft in an equatorial or low inclination orbit predictable roll disturbance torques due principally to solar radiation pressure are minimized by interacting a magnetic dipole oriented parallel to the spacecraft's yaw axis with the earth's magnetic field. Signals either from an on board sun sensor or from an earth station are utilized by the satellite mounted magnetic switching and driver circuit to control the compensating torques.

Abstract: An omnidirectional circularly-polarized antenna system includes a plurality of dipoles equally spaced in a horizontal circle about a metal support mast. The dipoles are tilted at an angle with respect to the plane of the horizontal circle to excite circularly-polarized waves. The dipoles are fed in phase rotation with adjacent dipoles 90.degree. out of phase.

Abstract: The speed and direction of rotation of an electronically commutated brushless D.C. motor is controlled by utilizing a resolver to provide both phase locked servo feedback and motor commutation. The resolver in response to orthogonal signal voltages on its primary coils, provides a signal whose phase is a function of the motor shaft angle. A phase detector provides a signal whose phase varies in accordance with the difference between the phase of the signal from the resolver and the phase of a reference signal. The reference signal phase varies in a predetermined manner as a function of time dependent upon the desired shaft speed and direction of rotation. The phase detector output signal is then used to amplitude modulate the signal from the resolver. The amplitude modulated signal is then demodulated with respect to the orthogonal signal voltages so as to provide signals to energize the control coils of the motor.

Abstract: An input circuit for a wide acquisition range minimum shift keying demodulator includes a pair of phase-locked loops (PLL). Each PLL is designed to receive from a frequency doubler a respective one of two discrete spectral lines in the frequency spectrum separated by a frequency equal to the bit rate. Each PLL operates at one of three frequencies including its own search position frequency and the search position frequency of the other PLL plus or minus the bit rate. A logic decision circuit responsive to the PLLs operates with a frequency synthesizer connected to a mixer at the input of the doubler so that when one PLL locks to one spectral line, the other PLL is operated at its respective frequencies to lock to the other spectral line.

Abstract: A digital tracker in a cooperative collision avoidance system utilizing time division techniques, which is capable of generating track gates and determining critical values of tau (time to collision) for at least 16 targets during the same time frame, the maximum number of targets being limited essentially by the size of the logic memory elements used and the maximum range desired.

Abstract: Control of an active three-axis multiple-wheel attitude control system is provided with a bias momentum to achieve stiffness about the pitch axis. With this stiffness, the system overcomes the inherent inability of a zero momentum system employing the sun as its yaw reference to be provided with this yaw reference during the periods encompassing satellite high noon and midnight (i.e., approximate coalignment of the sun line and the local vertical). The satellite attitude is normally maintained by angular momentum exchange developed by three or more reaction wheels positioned on the satellite. The control mechanism is arranged to provide net angular momentum in the pitch axis wheels to achieve the momentum bias or stiffness along the pitch axis, whereas the time average of the angular momentum about the roll and yaw axes is substantially zero.

Abstract: In an electro-optic laser beam modulation system wherein the polarization modulation of the laser beam is converted into intensity modulation by an analyzer positioned in the path of the beam, a pair of photo-electric detectors detects a portion of the input and output beams. A divisor registers the ratio between the intensities detected. A compensator rotates the polarization of the output beam to establish a desired ratio, and a comparison system is connected to the divisor and the compensator to maintain the desired ratio.

Abstract: In a cooperative collision avoidance system, probe signals are inhibited for a predetermined time period to prevent autogenetic false alarms, that is, false replies to one's own interrogation probes.

Abstract: In an arrangement for evaluating an incoming speech signal to enable the selection of a receiver with the best quality speech signal over a substantial range of input signal levels, the logarithm of the input signal is processed in an absolute value and filter circuit to obtain the envelope of the logarithm of the input waveform which is next applied to a peak detector and to a valley detector. The output voltage of the peak detector is proportional to the logarithm of the speech peaks, and the output voltage of the valley detector is proportional to the logarithm of the noise floor voltage during the speech pauses. The peak and valley detector output voltages are applied to an arithmetic circuit which provides a voltage that is a function of the ratio of the speech peaks to the intersyllable noise floor.

Abstract: Attitude of a pitch momentum biased satellite in a low inclination orbit is controlled by a closed loop magnetic torquing control system. A magnetic dipole oriented perpendicular to the satellite's pitch axis in the roll/yaw plane and at a predetermined azimuth angle relative to the roll axis minimizes roll and yaw errors by interaction with the earth's magnetic field. Signals from an on-board roll attitude sensor are used by satellite mounted detection and driver circuits to control the compensating torques. Magnetic torquing is initiated whenever the roll error as measured by the roll attitude sensor exceeds a predetermined threshold.

Abstract: A linear/circularly polarized antenna system is provided by four conductive elements. The conductive elements are joined in pairs at their ends with the joined ends spaced by a conductive support member from a flat reflector. The lengths of the conductive elements of each dipole element are changed from being equal lengths of approximately a quarter operating frequency wavelength to one slightly longer and the other slightly less than a quarter wavelength to selectively change operation from that of a linearly polarized antenna to that of a circularly polarized antenna.

Abstract: A system, which selects the most desired signal from similar signals provided by two or more radio receivers, includes a separate arrangement of a signal quality detector, a signal selection gate, and a comparison circuit for each of the similar signals. Each detector provides an output signal level indicative of the quality of the particular one of the similar signals to which it is responsive. The comparison circuits determine from the various detector output signal levels the better signal among the similar signals and provide a control signal to the selection gate in the arrangement including the detector indicating the better signal. The selection gate in the arrangement responsive to the better signal in response to the control signal passes the better signal out of the system. A priority bus is common to all of the above-mentioned arrangements responsive to the respective similar signals.

Abstract: A helical resonator includes a helical coil within a metal enclosure, with the windings at one end of the coil reduced in diameter and shorted to each other so as to form a cylindrical conductive member. The cylindrical conductive member provides one plate of a variable capacitor the other plate of which is partially formed by one wall of the enclosure which is adjacent to the windings of reduced diameter. A screw extends through the one wall of the enclosure and into the cylindrical member. An adjustment of the screw controls the resonant frequency of the cavity.

Abstract: A digital tracker in a cooperative collision avoidance system capable of generating track gates and determining critical values of tau (time to collision) for at least 16 targets and to determine the presence of two targets of substantially similar ranges and to track two such co-range targets.