Abstract: Cost and weight of a heat transfer structure for a space vehicle can be reduced by an arrangement of redundant channels for the flow of coolant to heat radiating panels, micrometeroid resisting bumpers located adjacent the channels for preventing penetration by all but the most energetic micrometeroids, and a sensing and control arrangement for sensing the penetration of a coolant channel for shutting off that channel to prevent loss of coolant.

Abstract: An overdrive control for a GaAs FET power amplifier is provided by a PIN diode attenuator positioned at the input of the FET amplifier where the amount of attenuation is controlled by a control signal derived from the gate current of the following FET amplifier.

Abstract: A high data rate optical network data communication system includes a receiver including a photodiode detector, a data slicer and a data decision circuit. A clock recovery arrangement includes an impulse generator coupled to the data slicer to generate impulse signals. The impulse generator includes a high speed ECL NOR gate driven by mutually out-of-phase and relatively delayed data. The impulse signals are applied to ring a coaxial cavity by way of a resistor and an input magnetic coupling loop. The coupling loop allows the cavity to achieve high Q so it will oscillate for a relatively long time, and also provides a path by which bias is applied to the output of the NOR gate to fulfill ECL biasing requirements. The cavity Q is maintained high by coupling signals from the cavity by way of a second magnetic coupling loop. The oscillations are applied by way of a limiter to the data decision circuit.

Abstract: An unbalanced quarternary phase-shift keying modulator provides relatively higher signal power for one of two signal information channels. The carrier to be modulated is split into two equal-amplitude, equal-phase portions, each of which is applied to a biphase modulator. Each of the information signals is also applied to one of the biphase modulators, for producing two equal-amplitude, phase modulated carriers, each biphase modulated by one of the information signals. The modulated carriers are applied to the ports of a quadrature hybrid coupler which is other than a 3 dB (equal-amplitude) coupler. In one embodiment, the coupler is a 7 dB coupler. The modulated carrier applied to the through port of the coupler appears with reference amplitude and phase at the output of the hybrid. The modulated carrier applied to the other or coupled port appears at the output with relatively reduced amplitude and a relative phase shift. In one embodiment, the phase shift is 90.degree..

Abstract: A novel material is disclosed which is the reaction product of acrylic acid and a novoloid fiber. The material has excellent ablative and flame resistant properties.

Abstract: A set of magnetically responsive vanes are secured for rotation about their mass center of gravity in a given angular spacing. The vanes have corresponding magnetic field producing coils which are in a different angular spacing such that one coil and vane is aligned and a second coil and vane are misaligned. An electrical switch is coupled to the vanes for operation in response to rotation of the vanes. A current applied to one coil aligns its vane thereto and closes the switch. The closed switch applies a load current to a second coil whose vane is misaligned. When an overcurrent occurs, the corresponding resulting field aligns its vane and opens the switch. An off current applied to a coil can align a corresponding vane to also open the switch. The switch and actuator are dynamically balanced so that moments produced by shock and vibration do not operate the actuator vanes or switch.

Abstract: A nutation damping control for a dual-spin satellite is provided by tilting the axis of the rotor relative to the normal spin axis of the satellite and back a half nutation period later. The tilting is in the direction of the angular momentum vector component that is transverse to the rotor's spin axis.

Abstract: A balun comprises a one-to-two, equal-power, matched power divider having branch transmission lines whose lengths differ by 1/2 wavelength at a design frequency. The shorter of these two branch transmission lines has two 1/4 wavelength long, shorted stub transmission lines branching therefrom 1/4 wavelength apart.

Abstract: A power conversion system is constructed of a plurality of identical Stirling engine modules paired off in opposed, aligned relation with their respective expansion spaces in juxtaposition. Two engine module pairs are arranged in a common plane and in mutually perpendicular relation to create a module group, with plural such module groups stacked together to provide an expanded, self-balanced system with all the modules sharing a common, centrally located thermal energy source. Each module includes a pair of compression positions operating on a common axis intersecting the displacer cylinder axis at right angles. Heat exchangers, either tubes or heat pipes, are disposed within the expansion space to transfer heat from the source to the working fluid therein, thus providing a more idealized Stirling engine cycle.

Abstract: The present invention provides three embodiments of circuitry, responsive to the application of an energizing pulse to the high pressure tube of a hybrid laser, for de-energizing the normally continuously energized low-pressure tube of the hybrid laser for only a given time interval which is longer than the duration of the high-energy pulse of coherent wave energy generated by the high pressure tube when energized. This solves a prior-art problem of sporadic spike emissions by the low-pressure tube during the time interval in which echoes from objects of interest are being received by a LIDAR employing a hybrid laser transmitter portion.

Abstract: An electrically regeneratable fuel cell is disclosed which has positive electrodes comprised of an alloy of about 50 to 55 percent by weight of silver and about 50 to 45 percent by weight of indium. The fuel cell of this invention is chargeable to a higher voltage at a lower pressure, has a substantially higher capacity, lower internal resistance and is lighter in weight than comparable conventional electrically regeneratable fuel cells.

Abstract: A support fixture for a printed circuit board connector having L-shaped wire wrapping pins attached to a printed circuit board includes a plurality of L-shaped elements, each for placement in the L-shaped space defined by adjacent arrays of pins, connector body and printed circuit board. An outer L-shaped structure is juxtaposed with the pins at their bends and with the elements to preclude motion of the pins at their bends in response to wire wrapping forces on the ends of the pins protruding from the printed circuit board.

Abstract: An apparatus for testing the crosspoints of an RF switching matrix injects a test signal having the characteristics of noise into the matrix. The test signal recovered from the matrix is mixed with a frequency-swept signal and the difference signal is applied to a bandpass filter. The filter provides a window through which all of the frequency-shifted components of the recovered signal pass during the period of the frequency-swept signal. The total energy of the components in the window is continually monitored during the sweep period. A comb generator provides the test signal having a multiplicity of substantially equal amplitude components, uniformly spaced over a selected frequency spectrum. The frequency-swept signal is provided by a VCO having a sawtooth waveform input voltage. The amplitudes of the test signal components are sufficiently low that if coupling occurs between the test signal and a configured external antenna, the resulting transmission is virtually indistinguishable from noise.

Abstract: Thermoelectric elements of both P-type and N-type lead tellurides having unique characteristics including, particularly in the case of the P-type, a figure-of-merit 90% above that of the best commercial P-type element, are produced by a new process involving as key steps chill casting, cold pressing and sintering to 85-90% theoretical density under protective atmosphere.

Abstract: A burst mode fiber optic or light-wave communication system uses as a transmitter a light emitting device requiring drive current to produce a light output. The characteristics of the light emitting device change with time, so the drive current must be periodically adjusted. In a high speed burst data system, the magnitude of the light output and the new value of drive current cannot be determined until a time well after the beginning of the burst, or possibly after the burst has ended. If the drive current is adjusted to a new value during burst transmission, the change in light output may be interpreted by a receiver as a data transition, which may result in data errors. The change in the control signal which controls the magnitude of the drive signal is delayed until a time between data bursts, whereby the drive current magnitude remains constant during any burst transmission.

Abstract: Thermoelectric elements of both P-type and N-type lead tellurides having unique characteristics including, particularly in the case of the P-type, a figure-of-merit 90% above that of the best commercial P-type element, are produced by a new process, involving as key steps chill casting, cold pressing and sintering to 85-90% theoretical density under protective atmosphere.

Abstract: A cover for a semiconductor package includes a composite layer on its upper most surface containing a passive circuit. The passive circuit may include a number of passive components to fulfill various functions such as capacitive coupling and decoupling, resistive pull-up and pull-down, et al. Appropriate terminal points of the passive circuit terminate in contacts which are disposed on the top surface of the composite layer. Terminals are attached to the contacts for interconnecting the passive circuit with terminal leads of the semiconductor package or other circuit components.

Abstract: An RF switch employing a PIN diode as the switching element includes a first bias circuit providing forward dc current through the diode to enable RF transmission therethrough, and a second bias circuit providing reverse dc voltage across the diode to disable RF transmission through the switch. Status circuitry monitors the switch for failure modes of the diode, and control circuitry selectively enables the bias circuits. A short circuit failure of the PIN diode is indicated by the flow of reverse current in the second bias circuit in excess of the diode leakage current. Under this condition, the reverse current is latched by a thyristor in the second bias circuit and the status circuitry generates an alarm signal to the control circuitry inhibiting further selection of the first bias circuit. Optical couplers provide electrical isolation of the first and second bias circuit from the control and status circuitry.

Abstract: An optical system is described for use in processing information on a surface of an erasable record disc. The system decreases erasure time by forming an elongated spot from the generally circular cross section of a collimated laser beam so as to provide increased illumination time to an area recorded on the disc. The system includes a source of collimated light having a generally circular cross section, a cylindrical lens for focusing one aspect of the collimated light at a finite distance f, and a beam expander having the principal plane of its input lens at the distance f from the cylindrical lens, where the light forms a beam waist. An objective lens focuses the expanded elongated beam to a diffraction spot on the surface of the record disc. A linear actuator, such as a voice coil, responds to a control signal to position the cylindrical lens in the path of the collimated light beam for the erasing process, or out of the light path for the recording process.

Abstract: A transmit/receive space diversity system communicates between transmitter-receivers at two separate sites. Each site has at least two antennas. Each antenna at a first one of the sites transmits a pilot signal, at differing frequencies. At the second or other site, all the pilot signals are received by each antenna, and the pilot signals are evaluated to determine which pilot-signal-receiving antenna is part of the lowest loss path between the sites. A data source at the second site is routed to the identified antenna for transmission of data signals back to the first site. At the first site, the data signals are received by all the antennas, and the best of the received data signals is routed to utilization apparatus. A data signal from the first site is transmitted to the second site, at which it is received by the selected antenna.