Abstract: A test assembly for automatically testing and diagnosing digital printed-circuit boards has a driver circuit for supplying a stimulus pulse to the circuit board to be tested, a sensor circuit for detecting the output from the circuit board in response to the stimulus pulse, a program for directing the testing operation of the test assembly, an input device such as a keyboard for entering instructions including the program to the test assembly, and an output device such as a printer for displaying the results of the test operation. The test assembly also includes a sense and hold circuit interconnected with the driver circuit, the sensor circuit and the circuit board, which senses the output pulses from the circuit board in response to the stimulus pulse, and provides an input pulse to the sensor circuit having a period greater than the minimum duration period capable of being detected by the sensor circuit.

Abstract: A decoding device for use in pulse compression radars to decode a novel pe code that has the advantage of precompression bandwidth tolerance. The novel code type is described by the following formula (where .DELTA..phi..sub.k,p is the phase change at the kth subpulse of the pth subsequence within the width of a phase-modulated pulse):.DELTA..phi..sub.k,p =(2.pi./N) [k+pN][p-(1/2)(N-1)]k=0, 1,2, . . . , N-1p=0, 1,2, . . . , N-1 (N any integer)The input signal is fed into multi-stage I and Q shift registers. Each stage in the shift register is fed into an adder, correlation being effected by first multiplying the real and quadrature parts of the signal stored in the stages of the I and Q shift register by a preselected multiplying factor, the sequence of multiplying factors corresponding to the time-reversed and negative phases of the transmitted pulse. The sum signal at the output of the adder corresponds to the auto-correlation function of the received signal.

Abstract: A process of fabricating an optical directional coupler switch for the TE- and TM-mode polarizations at a given wavelength. Initially, a trial set of waveguide fabrication parameters is used to fabricate a series of channel waveguide directional couplers having the same waveguide spacing and differing interaction lengths. The step is repeated for other waveguide spacings. The power splitting ratio of each directional coupler so fabricated is determined for guided light of one of the polarizations at the given wavelength. For each series of directional couplers having a respective common waveguide spacing, the arctangent of the square root of the power splitting ratio versus the interaction length is graphed and the coupling coefficient for the one polarization is found from the graph slope. The log of the coupling coefficients so determined is graphed versus the corresponding waveguide spacings. The previous three steps are repeated for guided light of the other polarization at the given wavelength.

Abstract: A broadband high frequency power oscillator employing a GaAs FET transistor and a two-port coupling network whose input port is connected across the drain and source terminals of the GaAs FET. The coupling network consists of 3 branches in T- or .pi.-configuration. One branch includes a matching network and the load. The other two branches are purely reactive and each includes at least one independently tunable reactance element, such as a varactor.

Abstract: A coupler employing two similar sections of waveguide which extend coliney in longitudinal succession. Adjacent ends of the guide sections are spaced apart to form a gap in the boundary of the sections. A third section of waveguide is disposed external to and coaxial with at least a part of each of the two waveguide sections to provide a boundary surrounding the gap. Electromagnetic energy propagating down one of the two similar sections of waveguide in a first mode and entering the gap is converted partly to a plurality of other modes. The converted energy is reconverted to the first mode upon reaching the other of the two similar sections of waveguide. The electric field pattern exciting the section of waveguide at the end of the gap and propagating down it is exclusively in the first mode.

Abstract: Free-electron lasers and masers are modified by eliminating the resonator cavity as such. The feedback mechanism, essential to oscillation, is distributed through and integrated with the transmission line which guides the electromagnetic wave at the active region where interaction with the electron beam takes place. The feedback structure is created by perturbations in the transmission line along the length thereof at the locations of the zero electric field lines of a desired oscillatory standing wave mode. The perturbations may take the form of axial, helical, and azimuthal deformation of the transmission line.

Abstract: An optical frequency division multiplex system including a transmitter, a receiver, and a transmission path connecting the transmitter to the receiver. In the transmitter a master laser is operated to produce a central peak at an optical frequency f.sub.o with side peaks separated by an amount .DELTA.f running to both sides of the central peak. The master laser output goes through an optical isolator to an optical coupler where it is split up into N+1 beams. Each optical output from the coupler is then positioned to be coupled into N slave lasers. Each slave laser is tuned to approximately coincide with one of the side peaks thus producing a single output frequency of (f.sub.o .+-.n.DELTA.f) from each slave laser diode. Electrical modulating signals for each of N information channels are applied separately to modulate the phase of each of the slave laser outputs. The outputs of the slave lasers are then recombined in a N.times.

Abstract: A phased array lens antenna which includes a lens having two faces disposed ubstantially at a right angle to each other. Transmit-receive modules which include phase-shifters are shared between the two lens faces. Two lens antennas positioned in back-to-back relationship about a ship superstructure scan 360.degree..

Abstract: A field-emitter switching device wherein a positive pulse is applied to a te (which is held at a bias potential V.sub.1 just below turn-on). A collector is held at a potential higher than the gate in order to collect emitted electrons from a field emitter source. As the voltage is applied to the gate, electrons are emitted immediately from the source and travel to the most positive potential at the collector. Because of the field emitter geometry, such electron transport is extremely fast. The ultra-fast switching speed is attained because the electrons reach near-maximum velocity within a few field tip diameters of the source.

Abstract: A circuit which detects environmental sources of echos received by a pulscho system such as a radar and classifies the sources of the echo at each range resolution cell as either short-pulse interference, rain clutter or jamming, distributed land clutter, an isolated target or thermal noise. The circuit implements on the screen of a cathode ray tube a digital map of a selected echo source type by modulating the electron beam intensity with a binary digit (0 or 1) at each increment of the sweep corresponding to a range resolution cell. The circuit utilizes a pulse-to-pulse noncoherent subtraction to remove correlated echos, leaving only uncorrelated type echos. Short-pulse interference is then detected and the uncorrelated echo component is compared to thermal noise to determine if rain clutter or noise jamming is present. The threshold for either target detection or land clutter is determined from the uncorrelated echo component, and all correlated targets and land clutter are next detected.

Abstract: An intense, space-charge-neutralized, pulsed ion beam is used to heat a magnetically-confined plasma, such as tokamak plasma, by injecting the ion beam into the plasma along a trajectory that is generally tangential to the confining magnetic field. The intense ion beam is injected into the tokamak before the plasma is fully formed, the remainder of the plasma is formed around the beam, and the beam transfers its energy to the plasma by classical collisions with the electrons and ions of the plasma. Heating of the plasma can be sufficient to produce breakeven or ignition.

Abstract: A process for patterning a target for lasing at X-ray wavelengths from materials which cannot be readily shaped. A substrate of one material is placed in a gaseous atmosphere of another material, and the substrate is cooled below the freezing point of the other material so that a frozen layer of the other material condenses onto the substrate. Part of the frozen layer of the other material is masked, and the unmasked part of the frozen layer is vaporized so that the substrate of the one material is coated with the other material according to the pattern of the mask. The target made by the process is also disclosed.

Abstract: A signal processor for generating the ambiguity integral using a modulatable, broadband, incoherent light source, a multiplicity of acousto-optic cells and diffraction gratings, and a two-dimensional time-integrating photodetector array. The various colors of the source spectrum are shifted by differing radio frequencies. These modified spectral components are also modulated by an input signal and serve as input sources for performing a multiplicity of correlations using an acousto-optic cell with an unknown Doppler-shifted signal. The answer is displayed on a two-dimensional time-integrating photodetector array where the spectral components are dispersed within the columns. The row corresponding to the color that has been properly frequency-compensated will contain the correlation or ambiguity peak, thereby identifying the Doppler component. Position within the row determines range.

Abstract: A method of welding two HY-steel members to produce a weld joint having improved impact toughness. The surface to be welded are first machined, roto-blasted and cleaned with acetone. Then, an insert of Inconel 600 is provided and cleaned with acetone. Next, the Inconel 600 insert is introduced between the surfaces to be welded and the HY-steel members are butted against the insert. Then, a laser welding beam is applied to the Inconel 600 insert to weld together the assembly of steel members and insert.

Abstract: A pulse expansion and compression system, especially useful for radar rang, comprising a pulse coder for expanding an input pulse and a pulse compressor of the matched-filter type. The coder consists of a plurality of delay stages into which the input pulse is fed, a discrete Fourier transform (DFT) circuit to which the output signals of the delay stages are fed by way of respective phase weights and for which every other frequency port is inverted prior to entry to a time-dispersion-means (TDM) comprising an arrangement of adders interconnected by delay stages for differently delaying the output signals from the DFT. The TDM output is fed to a phase modulator and then to the transmitter.The echo signals are conjugated, time-inverted, and passed through the same DFT as the input pulse signal by way of the phase weights. The outputs of the DFT are then inverted at every other frequency port and passed through the TDM, but this time in time-inverted order.

Abstract: A pulse expansion and compression system, especially useful for radar rang, comprising a pulse coder for expanding an input pulse and a pulse compressor of the matched-filter type. The coder consists of a plurality of delay stages into which the input pulse is fed, a discrete Fourier transform (DFT) circuit to which the output signals of the delay stages are fed by way of respective phase weights and for which every frequency port is phase-shifted prior to entry to a time-dispersion-means (TDM) comprising an arrangement of delay stages for differently delaying the output signals from the DFT. The TDM output is fed to a phase modulator and then to the transmitter.The echo signals are conjugated, time-inverted, and passed through the same DFT as the input pulse signal by way of the phase weights. The outputs of the DFT are then phase-shifted at every frequency port and passed through the TDM, but this time in time-inverted order.

Abstract: A system for polyphase encoding transmitted pulses of energy and for decog the received signals to enhance returns from the range interval being examined during a particular processing period and attenuate returns from contiguous range intervals (pulse compression). The system includes a decoding device which comprises a delay circuit having N distributed outputs including its input for producing a uniform delay between adjacent outputs corresponding to N inputted elements of a received phase-coded signal of length N.sup.2 ; a conjugator circuit coupled to the first N/2 successive outputs of the delay circuit; a first signal-combining circuit coupled to the conjugator circuit and to the last N/2 successive outputs of the delay circuit; a multiplier circuit coupled to the first signal-combining circuit; and a second signal-combining circuit coupled to the multiplier circuit. The decoding device provides a decoding phase shift -.DELTA..phi..sub.k,p to the signal elements of the phase-coded signal wherein.DELTA.

Abstract: A system for achieving very uniform illumination of a target. A beam of broadband spatially-coherent light is converted to light with a controlled spatial incoherence and focused on the target. An echelon-like grating breaks the beam up into a large number of differently delayed beamlets with delay increments larger than the coherence time of the beam, and a focusing lens overlaps the beamlets to produce at the target a complicated interference pattern modulated by a smooth envelope that characterizes the diffraction of an individual beamlet. On time scales long compared to the coherence time, the interference pattern averages out, leaving only the smooth diffraction envelope.

Abstract: A method of recovering intact at room temperature a layer of a first material, such as silicon carbide, produced by depositing it from the gas phase at a deposition temperature above room temperature on a substrate of a second material, such as silicon, having a different coefficient of thermal expansion than that of the first material. The substrate is separated from the layer prior to cooling, and then the separated layer is cooled to room temperature free of stresses otherwise present as a result of the different thermal expansions of the substrate and layer.

Abstract: A method of loading a cell of a vertical launching system missile launcher n a combatant ship with a canistered missile from a supply ship wherein the canistered missile is transferred from the supply ship to a fixed guide on the deck of the combatant ship, upended in the guide, moved away to a position over the cell of the missile launcher, and then lowered into the cell.