Abstract: A television signal encoding and decoding system providing a line-spin scrambled video signal with substantially reduced amplitude gaps and line tilt and a digitally-encrypted audio signal that can be transmitted within the bandwidth limitations of a conventional NTSC television signal. The television signal encoding system, located at a television transmitter, includes a video and an audio encoder. The video encoder selectively line spin scrambles, reverses and inverts certain video lines or video line segments to generate a line-spin scrambled video signal having amplitude gaps less than some desired value. The audio encoder digitally encrypts the audio signal and modulates the encrypted audio signal with a three-level partial response waveform to generate and encrypted audio signal that can be transmitted within the bandwidth limitations of a conventional NTSC television signal. The television signal decoding system, located at a television receiver, includes a video and an audio decoder.

Abstract: An improved thrust vector control system for steering and controlling an aerospace vehicle propelled by a reaction type motor. The improved thrust vector control system simultaneously rotates and laterally translates the reaction motor with respect to the longitudinal axis of the vehicle. This complex motion of the reaction motor generates sufficiently large control moments that allows the reaction motor to be moved very close to the center of gravity of the vehicle. As a result, the vehicle can be shortened and the structure that is typically required to position the reaction motor at a swivel point farther aft eliminated.

Abstract: A method and apparatus that compensates for line tilt in a video line scrambled by a line spin scrambling technique. Line spin scrambling provides relatively secure transmission of video signals, with a modest amount of complexity and cost. However, line spin scrambling suffers from certain distortions that corrupt the unscrambled video signal. One of these distortions is caused by line tilt, and results in a chaotic hashing of luminance striations in a received picture. The method of the invention includes the steps of measuring the amplitude of the line tilt introduced into a video signal, generating a complementary ramp based on the measured amplitude, and summing the complementary ramp with the spun video line.

Abstract: A free-electron laser including one or more diffraction gratings as part of a resonator structure, to automatically compensate for resonator reflector pointing errors. The angle of reflection of radiation incident on the diffraction grating is frequency-dependent, and this permits compensation of the pointing errors by small shifts in the frequency of operation of the laser, within its normal bandwidth of operation. The technique may be employed in various resonator structures, including a ring resonator.

Abstract: Apparatus for multiplexing or demultiplexing multiple laser beams of different wavelength. In multiplexing, the outputs from multiple diode lasers are combined in such a manner as to produce a practically parallel set of beams for direction onto a diffraction grating. The latter component deflects each beam from its normal path by an angular amount determined from the wavelength of the incident light. The angles of incidence of the multiple beams are chosen to provide angles of diffraction that are practically identical for all wavelengths under consideration. In demultiplexing, similar apparatus includes a diffraction grating to provide angular dispersion of the multiple wavelengths, at least one lens to magnify the angular differences, and a set of detectors positioned in the paths of the dispersed beams of different wavelengths.

Abstract: Switching circuitry for automatically connecting two sets of terminals in two circuit modules, through a larger set of conductors, some of which may be defective or unavailable for other reasons. The circuitry includes two identical switching matrices, each of which receives signals indicative of the availability status of the conductors, and connects the terminals to an available subset of the conductors. Each switching matrix has an array of switching cells arranged in such a manner that a cell will connect a terminal to a conductor unless the conductor is not available, or unless the same terminal has already been assigned to another conductor, or the same conductor has already been assigned to another terminal.

Abstract: A plasma type metal plating apparatus is characterized by a magnetically confined electrical plasma containing a high percentage of metal ions directed toward the target substrate, containing the passages with passage walls to be plated, and means for increasing the longitudinal velocity of the moving ions of the plasma in the region of the substrate prior to incidence of those ions on the substrate. The method of plating minute diameter high aspect ratio holes in microelectronic integrated circuit substrates employs steps of directing an electrical plasma containing a high percentage of metal ions, suitably 80% or greater, toward the microelectronic substrate; and adding energy to the plasma in the vicinity of said substrate to increase longitudal movement velocity of the ions prior to incidence of said ions on said substrate.

Abstract: An analog-to-digital converter quantizer and bidirectional counter using superconducting quantum interference devices (SQUD's) as the principal elements. A double-junction non-latching SQUID is used as a quantizer to produce unipolar output pulses on two different output lines, indicative of positive and negative increments of change in an analog signal current. The unipolar pulses are then counted in a bidirectional counter that employs double-junction non-latching SQUID's as counter stages and as logic gates for the propagation of carry and borrow signals from stage to stage.

Abstract: Spacecraft components having critical surfaces which must arrive in outer space in a contamination-free, pristine state to assure their effecient operation over the entire spacecraft mission life are protected against contamination by applying to the surfaces a protective coating which sublimes away when exposed to the outer space environment, thereby exposing the surfaces in their pristine state to the environment.

Abstract: A semiconductor diode structure including a light-absorbing substrate, an active region, and a pair of cladding layers surrounding the active region. Lasing is inhibited by means of an inclined end facet, which reflects light down into the substrate, where it is absorbed, to provide only one pass of the spontaneously emitted light through the active region. One disclosed embodiment has a conventional end facet for the out-coupling of edge-emitted light. Another embodiment includes a surface-emitting facet formed in an opening in the substrate adjacent to the inclined facet. Yet another embodiment has two inclined facets. One inclined facet may serve to reflect light into the absorbing substrate, or both may serve to reflect light through separate surface emitting facets.

Abstract: A multipurpose modular spacecraft is adaptable quickly and easily for performing a variety of short- and long-range space missions, such as on-orbit maintenance missions and the like. The multipurpose modular spacecraft comprises a fully integrated short-range space vehicle including one or more relatively small modular propulsion sets which provide propulsion capability for relatively short-range missions and close-in maneuvering requirements. Longer-range propulsion capability is provided by a comparatively larger propulsion module designed for removable nested mounting within an open-sided chamber in the short-range vehicle. Relatively simple and easily operated latch mechanisms retain the propulsion sets and the propulsion module on the short-range space vehicle in preselected positions with relatively simple electrical fittings connected together to provide a control interface with the short-range space vehicle.

Abstract: An optical filter and detector, and a related method for its operation, in which signal photons are admitted into a detector cell and selectively excite atoms or molecules of a vapor to a selected metastable state. An illuminating laser then photoionizes a large proportion of the excited atoms or molecules, and the resulting free electrons are collected as a measure of the number of incident signal photons. The initial excitation step to a metastable state is highly sensitive to the wavelength of the signal photons and therefore acts as a narrowband filter.

Abstract: An analog-to-digital converter employing superconducting quantum interference devices (SQUID's) to produce countable voltage pulses at uniformly spaced quantization levels, the converter having multiple SQUID quantizers, each of which receives an identical analog signal current to be converter to digital form, and a bias current to provide an offset in the position of the quantization level for each quantizer. For a quantization current of .DELTA.i, the bias currents in each of 2.sup.n quantizers are 0, .DELTA.i/2.sup.n, 2.DELTA.i/2.sup.n, and so forth up to (2.sup.n -).DELTA.i/2.sup.n. The outputs of the quantizers are monitored in associated flip-flop circuits, the states of which are sampled and decoded to yield an n-bit output that can be combined with the output of a binary counter monitoring just one of the quantizers. The quantizers provide outputs that are effectively interleaved between adjacent quantization levels of a single quantizer.

Abstract: An electrooptically tunable waveguide array combined with a semiconductor phase-locked laser array, to provide both amplitude shaping and phase control of the optical output. The tunable waveguide array includes an input waveguide array section with an array spacing matching that of the laser array, a tunable coupling array section for tailoring power distribution among the array elements, a tunable phase shifter array section for tailoring the relative phase distribution among the array elements, and an output waveguide array section of various possible configurations. The tunable waveguide array can be implemented either externally, independent of the laser array, or incorporated into the laser array to form a composite cavity-array.

Abstract: A multilayer printed circuit board in which multiple layers of a composite material, fabricated by the lay-up of an aramid fiber tape, are employed to provide a circuit board with a desired coefficient of thermal expansion. Tape lay-up of aramid fibers provides a composite layer having a lower thermal coefficient of expansion than a composite layer fabricated from woven aramid fibers. Degradation in the tensile modulus of elasticity caused by the over and under characteristics of woven fabrics is also eliminated by tape lay-up, thus providing a circuit board with better mechanical strength. In addition, tape lay-up reduces the amount of resin required to fabricate the circuit board and eliminates the need for twisting the aramid fibers into yarns and then weaving the yarns, thus reducing the cost of the circuit board.

Abstract: A process for the catalytic production of hydrogen, from a wide variety of low heating value fuel gases containing carbon monoxide, comprises circulating a carbonaceous material between two reactors--a carbon deposition reactor and a steaming reactor. In the carbon deposition reactor, carbon monoxide is removed from a fuel gas and is deposited on the carbonaceous material as an active carbon. In the steaming reactor, the reactive carbon reacts with steam to give hydrogen and carbon dioxide. The carbonaceous material contains a metal component comprising from about 75% to about 95% cobalt, from about 5% to about 15% iron, and up to about 10% chromium, and is effective in suppressing the production of methane in the steaming reactor.

Abstract: An array of semiconductor lasers formed in a single substrate and having parallel waveguides that terminate in a wide diffraction region fabricated with the array structure. The diffraction region has a curved reflective surface selected to achieve a desired degree of coupling among the elements of the array, and to enhance and stabilize a preferred lateral mode of oscillation.

Abstract: A semiconductor laser diode array structure in which interelement losses are deliberately included, to favor operation at higher-order array modes of operation, and thereby avoid the disadvantage of beam broadening that results when lower-order array modes of operation are used at very high drive currents. To provide a desirable far-field radiation pattern, the structure includes a wide-waveguide interferometric configuration to select only the lowest of the higher-order modes. The desired interelement losses are obtained in the illustrative embodiment by a buffer layer that provides antiguiding in a transverse direction, but only in the interelement regions. The buffer layer is transparent, for strong interelement coupling and stability of operation. The illustrative embodiment was operated at drive currents in excess of four times threshold current, and with beam broadening only slightly above the diffraction limit.

Abstract: A high-resolution shaft encoder and a related encoding method for accurately measuring angular position and velocity of rotating shafts. The high-resolution shaft encoder includes an annular-shaped actuator ring that rotates at high speed, a shaft centered within the actuator ring, and an encoder housing. The shaft encoder generates measurements of shaft position .theta..sub.p and velocity .omega..sub.p, with respect to the encoder housing, from measurements of three time intervals t.sub.p, t.sub.r and .DELTA.t. These time interval measurements are computed from the output of a sensor element positioned on the shaft and a sensor element positioned on the encoder housing, both of which respond to an input actuation element positioned on the rotating actuator ring.

Abstract: A semiconductor light-emitting device structured similarly to an index-guided laser, but having waveguide channels that are formed at a selected small angle of inclination with respect to a direction normal to cleaved facets formed in the structure. The angle of inclination should be at least half the critical beam angle above which total internal reflection will not occur within the waveguide channels. The angled condition of the waveguide channels ensures that effective mirror losses at the facets exceed the modal gain of the device, so that lasing will not occur, even when the current and power are increased to high levels. The device produces up to 30 mW or more of output power at a large spectral bandwidth and small coherence length.