Abstract: Relatively large parts, such as large fasteners and the like, are mass electroplated in a plating drum rotatable in a plating solution, without damaging contact of the parts with one another, by confining the parts in separate plating cells of the drum containing openings for circulation of plating solution through the cells and electrodes between which the parts move back and forth during drum rotation to effect exposure of the entire surface area of each part to the electroplating action.

Abstract: A redundancy switching system particularly suitable for transponders of the type used in spacecraft. A plurality of elements such as amplifiers is selectively connectable to a similar plurality of terminals such as input or output ports by switches. For each amplifier there is provided one switch and the switches are interconnected to form a closed loop. The switches may have three or four-port configuration and may be double-pole or triple-pole transfer switches, wafer switches, waveguide transfer switches or the like. In another form of the invention each element is connected to one output port by a switch and additional redundant elements are cross-connected to each other by extra switches so that failed elements can be replaced by standby elements.

Abstract: One of the isotopes of an element having several isotopes can be separated from the others in a dense, neutral plasma. Thus initially a neutral plasma is prepared including the element in question. This may consist of positive ions and negative electrons or alternatively of positive and negative ions, or else of a mixture of positive ions, negative ions and electrons. The plasma may then be injected into a magnetic field or may be generated in the field where more energy is imparted to a selected isotope than to the others. Finally, the isotopes are separated from each other on the basis of their differential energies. For example, the selected isotope may be given more energy than the others by stimulating it within the plasma at its resonant frequency which may be close to the cyclotron frequency, either by an electric field or by a magnetic field.

Abstract: A vertical dipole antenna for the ELF (extremely low frequency) range. The antenna provides a series resonant circuit consisting of an inductor and the distributed capacitance of the conductor such as a wire which may be carried by lighter-than-air craft. The lighter-than-air craft may be conductive, in which case it contributes to the capacitance or the capacitance may be solely represented by the wire. The antenna may be frequency or phase modulated. In case of frequency modulation the frequency of the generator must be changed accordingly so that the series resonant circuit remains resonant at the frequency to be radiated. The antenna can be readily moved. A plurality of antennas may be provided to form a super-radiant array.

Abstract: A laser of the type which generates linearly polarized light and including optical means for self-alignment. Among such polarized lasers are, for example, solid state lasers and particularly ruby lasers, as well as various gas lasers employing Brewster windows. The problem is solved by utilizing a corner reflector in the laser cavity which generates two parallel laser beams. In order to achieve effective laser operation the polarization determining aspect of the laser, that is the crystal axis or Brewster windows, must be so oriented with respect to the corner reflector that the laser beam in passing through the laser is so reflected by the corner reflector that the light will return through the laserable material with the same directon of polarization as that of the original laser beam generated by the laser.

Abstract: An improved holographic instrument for evaluating the structural integrity of a load-bearing structure by recording on a holographic recording medium two successive holograms of the structure under differing stress conditions to produce a holographic interferogram containing information defining a deformation fringe pattern representing the deformations in the structure resulting from the change in stress conditions. A holographic recording unit for the optical signature instrument and for general holographic recording use.

Abstract: An inert diluent such as N.sub.2, He, Ar, etc., is injected into the reactant streams emerging from the cavity nozzle of a CW, supersonic, laser to increase the cavity power and lower the cavity temperature by enhancing mixing of the reactant stream while maintaining high pressure recovery.

Abstract: Disclosed is a method and apparatus for remote sensing of the salinity of large bodies of water.A sequence of intensity values is obtained for the horizontally and vertically polarized components of sunlight specularly reflected as a solar glitter pattern at successive points on the surface of the body of water. For readings corresponding to each pair of points, the fractional change of horizontal and vertical component intensity between the points is computed, as in the ratio of the fractional change in the vertical component to the fractional change in the horizontal component. If the ratio is sufficiently near a theoretical value, dependent on the solar zenith angle, to indicate that the corresponding intensity changes were actually caused by a change in salinity, the salinity change is calculated using formulae derived from the Fresnel equations.

Abstract: A microwave bandpass filter of the coupled bar type providing either an interdigital or combline structure. The filter consists of a plurality of resonator sections having two ground planes and a resonating bar integral with the structure and extending perpendicularly from one of the walls and parallel to the ground planes. The spacer sections match the dimensions of the resonator sections, but may have different widths thereby to control the spacing between adjacent resonator bars. Alternate resonator sections and spacer sections are mechanically interconnected to form a filter of the desired electrical properties.

Abstract: Disclosed is a multiple output DC-to-DC converter. The DC input power is filtered and passed through a chopper preregulator. The chopper output is then passed through a current source inverter controlled by a squarewave generator. The resultant AC is passed through the primary winding of a transformer, with high voltages induced in a plurality of secondary windings. The high voltage secondary outputs are each solid-state rectified for passage to individual output loads. Multiple feedback loops control the operation of the chopper preregulator, one being responsive to the current through the primary winding and another responsive to the DC voltage level at a selected output.

Abstract: An exposure control for automatically controlling the duration of the exposure time for a photographic material to be printed. The light intensity is sensed by a sensor which could be either of the photoresistive or the photovoltaic type. A range control controls both the light sensor circuit and a timer control. The range control permits to return the indicator to a permanent mark despite variations of the lens aperture, negative density, degree of enlargement and the like, while simultaneously increasing or decreasing the length of a standard timing signal. The timing signal in turn controls the printer lamp to determine the exposure time.

Abstract: A demodulator for a biphase or quadriphase shift-keying system. The demodulator includes two AND gates for biphase demodulation. The AND gate is one which will provide an output signal if and only if the two input signals are in phase. Each of the AND gates forms a feedback with an injection locked oscillator. Therefore depending on the phase of the input signal, one or the other AND gate provides an output which is then injected at the proper phase into the injection locked oscillator. The output of the AND gates is fed to a data logic and envelope detector to recover the data. For quadriphase phase-shift keying, four AND gates are required. The circuit can be constituted either by transistors or by transferred electron devices sometimes called Gunn effect devices.

Abstract: A system for transmitting digital information such as audio or video over a lossy or dispersive medium. The digital information is of the type where certain bits are more important than others and hence the less important bits can suffer a greater bit error rate. Accordingly, the most important bits are encoded into a (7,k) 8-ary Reed Solomon code where 7 is the length of the code and k is the dimension of the code. The less important bits are then respectively encoded into a (7,k+1) or a (7,k+2) 8-ary Reed Solomon code. The code words are modulated onto a plurality of tones or subcarriers. The decoding is effected by initially demodulating the subcarriers and generating a candidate set of code words from each 7-tuple of demodulated 8-ary symbols corresponding to a transmitted code word.

Abstract: A cell is fabricated using a solid alkali metal anode and a fluid cathode which are separated by a modified aluminate solid barrier which permits the flow of only the alkali metal ions. The fluid cathode can contain a solid, gaseous, or liquid oxidizer in a liquid electrolyte. Operating temperatures for these cells range from less than -40.degree. C to approximately 95.degree. C. At ambient temperatures, energy densities of the cells range from approximately 0.7 to 1.8 watt-hour per cubic centimeter. These cells are electrically rechargeable by raising their temperature above the melting point of sodium.

Abstract: An impulser for percussively loading a structure to generate stress waves in the structure by driving a hammer into impact relation with the structure and generating an electrical signal in timed relation to the impact. The impulser may embody means, such as suction cups, for firmly attaching the impulser to the structure and an anvil which is interposed between the hammer and structure and spring loaded against the structure for transmitting the hammer impact to the structure without damaging the structure.

Abstract: A low pressure gas laser is provided with an aerodynamic window for the generated high power laser beam. The window comprises a duct with an oblique opening located in the supersonic part of and aligned with the axis of a Laval nozzle, having an atmospheric entrance. This permits extraction of the beam from the laser without any contact through a solid window.

Abstract: A bifilar helical antenna which will radiate or receive in the backfire mode. The antenna consists of two interlaced helixes fed at the tip. Each helix is fed by a transmission line with energy of equal amplitude but 180.degree. out of phase. Optionally the helixes may be connected to a ground plane at the far end for mechanical stability. For the same reason an insulating right cylinder may be used to support the helixes. The two helixes have such a diameter and such a pitch or pitch distance that the currents flowing from their terminals to the far end are out of phase while the currents flowing in the reverse direction are in phase to provide a fast pseudo wave structure.

Abstract: An improved feedback control system to govern the cyclic operation of the power switch of a non-dissipative power conditioning equipment. The apparatus includes two or three control loops working in unison. The first causes the output DC level to be compared with a reference, and the error amplified for control purposes. The second utilizes the AC component of the voltage across the output filter inductor or the current through the output filter capacitor, and the third loop senses the output transients.

Abstract: An acousto-optic device suitable as a correlator, convolution integrator or Fourier transform device. The device comprises a piezoelectric substrate or crystal such as lithium niobate. The substrate is covered by a thin, outer layer having higher index of refraction than the substrate and a thickness on the order of 50 micrometers. Two acoustic transducers such as interdigital transducers are disposed on opposite ends of the crystal to launch two acoustic surface waves in opposite directions. A laser beam is guided through the outer layer and is coupled with the two acoustic waves to generate either a correlation function, a Fourier transform or a convolution integral depending on the signals impressed thereon.

Abstract: In delay module means, an input signal is divided into a number of subsignals, each separated from the others by a selected time delay. In a primary module the subsignals are selectively weighted and combined with the input signal. In the inverse module, the signal is similarly differentially delayed and weighted, and subtracted from the input by feedback loop means. Audio signal scrambling is accomplished by passing the signal through one or more primary and/or inverse modules in series; descrambling is accomplished by passing the scrambled signal through a complementary series of modules. Frequency translation and/or inversion is also applied for applications requiring increased security.