Abstract: A light viscoelastic damping structure has a plurality of damping strips widely separated on the surface of a lightweight panel. The strips may be arranged parallel or at right angles to each other. Each damping strip includes a viscoelastic damping layer, a first honeycomb structure having opposing face sheets and attached to one surface of the damping layer, and a second honeycomb structure having face sheets on opposing sides thereof attached to the damping layer and to the panel.

Abstract: The detector is responsive to a modulated intermediate frequency (IF) or radio frequency (RF) signal for producing four sample signals spaced at 90.degree. one-quarter IF (or RF) cycle apart, the first and third sample signals corresponding to the amplitude of the IF signal and its negative value, respectively, the stream of such sample signals corresponding to the inphase component of the IF signal; the fourth and second sample signals corresponding to the amplitude of the IF signal and its negative value, respectively, the stream of such sample signals corresponding to the quadrature component of the IF signal.

Abstract: A Stirling engine heater head is constructed to provide an annular heat exchange region defined between a pressure vessel sidewall and the engine displacer cylinder. From an external manifold, through which a heated fluid flows, either heat pipes or heat exchange tubes are sealingly introduced into the heat exchange region. Thermal energy is thus transferred to the engine working fluid, while the heated fluid is maintained isolated from the vessel walls and the displacer cylinder. For a compound Stirling engine configuration, thermal energy is introduced from a common heated fluid manifold to the heat exchange regions of a pair of axially aligned Stirling engine modules via heat pipes or heat exchange tubes. This manifold may be sealingly joined with the pressure vessel to create a chamber which is pressurized to pressure balance the vessel walls.

Abstract: An apparatus for breaking the periodicity of the pseudorandom bit stream output from a linear sequence generator. The apparatus includes a ring oscillator which periodically corrupts the sequence of the generator. The level of the supply voltage applied to the logic elements of the ring oscillator is varied over time, thereby altering the oscillator output frequency. In a second embodiment, the temperature of the logic elements of the ring oscillator is varied over time, thereby also altering the oscillator output frequency. A system comprising four of the above-disclosed apparatus having different linear sequences and different corrupting influences, are multiplexed, wherein the multiplexing selection criterion is determined by a logical combination of the four linear sequences.

Abstract: A multi-beam optical recording system includes a semiconductor laser array. The laser beams are expanded via a prism beam expander to have generally circular cross-sections for optimum spot intensity on the recording medium. According to the teaching of the prior art, the average beam angle of incidence on the input prism of the beam expander is the Brewster angle. According to the present invention, means are provided for rotating the beam expander to minimize the variations in spacing between beams, these variations resulting from the magnification distortion of the prisms of the beam expander.

Abstract: A switch-mode power supply includes the series combination of an inductor and a controllable switch adapted to be coupled to a voltage source for producing a succession of increasing and decreasing ramp currents through the inductor. The average value of the ramp currents is controlled by a feedback loop. A second controllable switch arrangement is coupled for causing the current leaving the inductor to recirculate through the inductor during those intervals in which the second switch is conductive. An integrator is coupled to the inductor for integrating ramp current from the inductor during those intervals in which the second switch is nonconductive, for generating load voltage. A second feedback arrangement senses the load voltage and controls the average conduction of the second switch to control the load voltage. In one embodiment, an inverter receives ramp current from the inductor and generates alternating current, which are transformed and rectified before application to the integrator.

Abstract: An adaptive interference cancelling signal processing system includes N+1 processors for cancelling N interfering auxiliary signals from a primary signal. During a prelook or inactive period of the primary signal when a component of interest is not present in the primary signal, the N+1 processors are configured to produce the N(N+1)/2 correlation coefficients L.sub.ij which enable weights for the auxiliary signals to be determined. The same N+1 processors may be reconfigured to convert these L.sub.ij values to the N weights without requiring matrix inversion. The N+1 processors may be reconfigured to multiply the auxiliary signals by the N weights during an active period of the primary signal when the component of interest is present in the primary signal. These weighted auxiliary signals are combined with the primary signal to provide a modified primary signal from which correlated interference in the auxiliary signals has been cancelled.

Abstract: Satellite is maintained in the geostationary orbit about the equator by use of solar sails. These solar sails are oriented to use the sun's radiation pressure to sail the satellite in a first direction for a first portion of the orbit and in a second opposite direction during a second portion of the orbit to counteract the forces tending to pull the satellite out of its equatorial orbit.

Abstract: A method and system is described for simultaneously precessing and nutation damping a spinning spacecraft that includes a computer, thrusters for precession and nutation damping and gyros aligned with or parallel to each of three orthogonal axes with the x-axis being the spin axis. The gyro information from three orthogonal axes is used to compute the momentum vector and target vector. The error vector is computed from the computed momentum vector and target vector. When the error vector's component along a given axis orthogonal to the x-axis changes sign, the thrusters are fired to apply corrective torques according to a computed control error.

Abstract: A printed circuit dipole monopulse antenna includes a planar printed circuit substrate having a plurality of dipole antennas and a feed network including a sum and difference hybrid printed thereon. Low sidelobe and monopulse operation are provided along one axis of the antenna.

Abstract: An antenna selectively fed from a square waveguide in one of two orthogonal linear TE.sub.1,0 modes includes a transition between the square waveguide and a larger square horn. A transition arrangement including a plurality of thin conductive elements or vanes is dimensioned and located at the transition to provide a gradual transition between the smaller waveguide dimension and the larger horn dimension in the E plane, and an abrupt transition in the H plane, regardless of the polarization selected. The abrupt transition in the H plane converts some of the TE.sub.1,0 mode energy to the TE.sub.3,0 mode. The radiating aperture is at a predetermined distance from the transition arrangement so that the desired relative phase between the TE.sub.1,0 and TE.sub.3,0 modes may be established. The E-plane aperture distribution is unaffected by the phasing, but the H-plane aperture distribution can be controlled by selection of the appropriate relative phase in order to provide a more linear distribution than TE.sub.

Abstract: An array of flared horn antennas is adapted to be fed from circular waveguide. The apertures of the horns are closely spaced. Prior art horns with circular apertures leave gaps in the aperture. The gaps are eliminated, and the gain of the array is increased by about 1/2 dB by tapering the horns from a circular cross-section at the feed end to a hexagonal cross-section at the radiating aperture end.

Abstract: A composite amplifier includes a plurality of signal amplifiers. The amplified signals are coupled by transmission lines to node points for combination. In order to achieve a reduction in power below full output power, some of the amplifiers are deenergized. Shorting switches at selected points along the transmission lines are selectively rendered conductive to adjust the impedances to maintain impedance match. Short- or open-circuited transmission lines may also be switched in-circuit to aid in maintaining impedance match.

Abstract: A phase shifter uses a PIN diode or diode pairs operated in a switching mode to switch transmission-line elements for phase-shifting radio frequency or microwave signals. A drive circuit for each diode(s) includes a FET switch controlled by a first level of a bilevel control signal to apply B+ to forward bias the diode(s) with a forward current. When forward biased, the active region of the diode(s) becomes flooded with charge carriers. The first FET switch is turned OFF by a second level of the bilevel control signal, and a second FET switch is turned ON to apply a reverse bias voltage to the diode(s) to render them nonconductive. Before the diode(s) become nonconductive, the excess charge carriers must be swept out of the diode(s). To achieve fast switching, the second FET switch must draw a large current for a short time as the excess charge carriers are removed.

Abstract: A multidisk spindle includes a plurality of mounting plates affixed to a shaft for mounting an equal plurality of record disks thereon such that the disks are parallel to each other and perpendicular to the rotational axis of the shaft. The shape of the mounting plates and their dimensions relative to the central apertures of the record disks permit the record disks to be mounted to the spindle after it has been fully assembled. In this way the assembled mounting plates may be abraded to provide plane disk-mounting surfaces which are parallel to each other and perpendicular to the axis of rotation.

Abstract: A multi-beam optical record/playback system includes optical elements for directing pluralities of write and read beams as respective diffraction limited spots on the optically-sensitive surface of a rotating disk. The spots on the disk are positioned such that information can be read immediately after it is written. A prism is selectively interposed in the path of write beams for the purpose or erasing previously recorded information. The prism refracts the write beams, causing a shift of its diffraction limited spots to positions behind the corresponding read spots, thus allowing the read beams to track recorded information which is subsequently erased by the light from the refracted beams.

Abstract: A subranging A/D converter generates high and low voltages using first and second DACs. A voltage divider receives the high and low voltages to generate plural reference voltages. A bank of comparators compares the analog voltage which is to be converted to each of the reference voltages, and a clocked logic circuit generates an intermediate digital signal indicative of the analog value relative to the plural reference voltages. The intermediate signal is used to decrement the high voltage and increment the low voltage, so that the reference voltages produced by the voltage divider assume subrange values. The process is repeated for as many clock cycles as is required to converge the high and low voltages to equal the analog voltage.

Abstract: A composition suitable for forming polyalkylsilsesquioxane coatings is prepared by emulsion hydrolysis of one or more silanes in the presence of a nonvolatile, nonionic catalyst, a nonionic fluorochemical surfactant and sufficient water to only partially hydrolyze the silanes. The resulting stable composition will form the final resin upon exposure to atmospheric moisture. A novel resin, polymethyl/isobutylsilsesquioxane, is particularly suitable for such coatings.

Abstract: A coupler for extracting energy in the TE.sub.21 mode from a circular waveguide propagating energy in both the TE.sub.11 and TE.sub.21 modes, characterized in that an annular iris on the inner circumference of the waveguide and a longitudinally stepped transition portion of the waveguide define therebetween a TE.sub.21 mode resonant cavity which is coupled via a narrow axially extending rectangular slot contained in the wall portion of the waveguide which defines the cavity. At least one external resonant chamber may be provided on the waveguide through which the TE.sub.21 mode energy is extracted and transmitted to a detector thereof via the slot, which chamber cooperates with the resonant cavity to define a multiple resonant filter for improving the matching to the TE.sub.21 mode while reducing the perturbation to the TE.sub.11 mode.

Abstract: An end effector suitable for manipulating articles such as mail flats is disclosed. This end effector has parallel reciprocating arms having suction cups for gripping the article to be manipulated and mechanical grippers mounted on the arms outboard of the suction cups. These mechanical grippers may be actuated to provide a mechanical grip on a manipulated article in addition to the suction grip.