Abstract: The optoelectronic cross-point switch suitable for a broadband switching array includes a photodiode which converts an optical signal impinging upon it to an electronic signal and a biasing circuit for selectively reverse biasing the photodiode to render the photodiode responsive to the optical signal or forward biasing the photodiode to render the photodiode substantially non-responsive to an optical signal. The biasing circuit consists of positive and negative voltage sources and a controllable switch to connect the sources to the photodiode. A load circuit which is connected to the photodiode for developing the output signal may consist of a single resistor, a pair of series resistors, an operational amplifier with feedback or an rf transformer. The load circuit can also include an rf switching diode connected to the photodiode to improve isolation and to reduce the electrical power required to forward bias the photodiode.

Abstract: The conductivity cell consists of a first set of electrodes fixed rigidly to a second set of electrodes. Each set of electrodes has an insulating material support with an electrode well through it, and three spaced electrodes positioned sequentially within the well. In one embodiment, the support is a glass tube and the three electrodes are deposited on the inner surface of the glass tubes. In a further embodiment, the three electrodes are washer shaped conductive strips fixed within the electrode well and spaced by two washer shaped non-conductive strips also fixed within the electrode well. Each set of electrodes further includes a glass tubing fixed within the electrode well between each outer electrode and the outer end of the electrode well. In another embodiment, washer shaped electrodes are recessed in the wall of the electrode well such that the surface of the strips are flush with the electrode well surface.

Abstract: The prism light guide is a longitudinal hollow structure made of transparent dielectric material. The structure has substantially planar inner and outer surfaces which are in "octature". The hollow structure is formed of one or more longitudinal sections which may be bonded together with an adhesive having a refractive index similar to the refractive index of the sections. The cross-section of each section is preferably constant along the length of the section, and the surfaces in each section are flat and polished smooth. One preferred light guide includes a rectangular or square hollow structure made of four longitudinal wall sections bonded together. Each wall section has a planar inner surface and an outer surface having 90.degree. angle longitudinal corrugations. The dielectric material is acrylic plastic or optically clear glass and the light guide includes an outer jacket for protecting the outer surface.

Abstract: Apparatus for generating electric power directly from a supersonic gas flow. An obstacle is positioned in the supersonic gas flow to establish a standing shock wave having a potential gradient. A pair of electrodes, one located in the upstream direction from the shock wave and the other located in the downstream direction from the shock wave, are used to extract power from the potential gradient.

Abstract: The loudspeaker telephone apparatus consists of a hybrid circuit which interconnects a telephone line and its line balance impedance with receive and transmit amplifiers. These amplifiers are connected to a bridge circuit, the arms of which are formed from two pairs of similar coil groups located in two multi-filar moving coil loudspeakers. The coil groups in one loudspeaker are connected in series aiding while the coil groups in the other loudspeaker are connected in series bucking. In one arrangement, the bridge circuit may be connected directly to the amplifier, the receive amplifier being connected across the pair of coils in each loudspeaker and the transmit amplifier being connected across the junction between the pair of coils in each loudspeaker. In another arrangement, a second hybrid circuit is used to connect the bridge to the amplifiers which are connected to the hybrid by its amplifier terminals.

Abstract: A gas laser system which provides sequence lines of emission in addition to the regular lines. The system includes a discharge cavity having a discharge tube and a hot gas absorber cell. The lasing gas and the gas in absorber are identical and may be either CO.sub.2, N.sub.2 O or isotopes of this gas. The absorber cell is approximately 1/5 to 1/3 the length of the discharge cavity with the interior temperature of the absorber cell being greater than 200.degree. C. and the pressure within the cell being in the order of 20 torr.

Abstract: The apparatus generates a train of pulse signals in real time which are fed to a Plan Position Indicator radar display video bright-up circuit. A line is formed on the display at a bearing .theta..sub.R , the direction of a VHF/DF fix, and passes through a point having the coordinates R.sub.o, .angle..theta..sub.o .degree., the position of the VHF/DF receiver, with respect to the center of the plan position indicator rotating radial scan. The radial scan operates at a radar trigger pulse repetition frequency F and rotates at a frequency f to subtend an angle .DELTA..theta.=360.degree..times.f/F per scan. The apparatus includes an up-counter for storing a count of R.sub.o sin (.theta..sub.R -.theta..sub.o), and a down-counter coupled to the up-counter and enabled at the pulse repetition frequency F to receive the count from the up-counter. The down-counter is adapted to provide an output pulse signal to the video bright-up circuit when its count reaches 0.

Abstract: A frequency controlled microwave oven having an oven cavity, a frequency agile microwave source for energizing the oven cavity, a detector for detecting the power absorption in a load at various source frequencies within a bandwidth and a control circuit for setting the microwave source at frequencies as determined by the power absorption levels. The frequencies at which the oven cavity is energized are selected by the control system to obtain high efficiency, i.e. low power reflection from the cavity, and to obtain improved heating uniformity by the superimposing of various heating patterns produced by the different operating frequencies.

Abstract: The scanning microwave detection apparatus provides a moisture profile along the width of a predetermined sample such as a sheet or web. The apparatus includes a number of moisture sensors spaced along the width of the sample, such that each sensor couples microwave energy with a finite area of the sample. Each sensor is preferably a pair of horns with one located on each side of the sample to provide a microwave path through the sample. A first filter is coupled to the input of each sensor and a second filter is coupled to the output of each sensor. The pair of filters associated with each sensor is tuned to the same frequency, and each of the pairs of filters are tuned to a different predetermined frequency within a selected frequency band such that the sensors operate at different frequencies, within substantially non-overlapping frequency band-passes. The filters are preferably directional.

Abstract: A method and apparatus for switching an infrared radiation signal laser beam in which a semiconductor, capable of transmitting the signal beam without damage, is provided and upon which the signal beam is incident at an angle which may preferably be Brewster's angle. The surface of the semiconductor is irradiated by a second laser beam which has a sufficiently high frequency to produce free carriers in the semiconductor and which has a sufficient radiation intensity and time duration to produce a free carrier density greater than the critical density for the signal beam resulting in substantially total reflection of the signal beam from the semiconductor surface. In particular, a pulsed CO.sub.2 laser beam which is incident on a polycrystalline n-type germanium semiconductor is reflected by irradiating the semiconductor with a pulsed ruby or Nd:glass laser beam.

Abstract: The quadrupole mass spectrometer has four conventional rod-shaped poles symmetrically located about the ion injection axis. Opposite pairs of rods are interconnected and connected to an rf voltage source. A shield having a circular aperture is located at the output end of the rods to assure the stoppage of low mass particles. In addition, a stopping element also preferably circular is located on the axis at the output to assure the stoppage of heavy particles. A pair of grids incorporating the stopping element, are sequentially located at the output, normal to the axis, the first is connected to a dc voltage source to accelerate the remaining particles through the fringing field of the quadrupole and the second is connected to a dc voltage source to subsequently decelerate the particles.

Abstract: The single-sided microwave applicator has a section of a microwave waveguide with an open end for receiving microwave energy and an end which is electrically shorted. A slot is located in one of the wide sides of the waveguide extending along the center line from the shorted end. A conductive ridge is mounted within the waveguide extending upward from the other side through the slot. One end of the ridge is connected to the shorted end of the waveguide, while the other end of the ridge is tapered from a point within the slot. The slot is generally in the order of 3/4 to 1 inch and at least 21/2 inches long, when the operating frequency is 2450 MHz. Since one end of the waveguide is shorted, standing waves are produced resulting in a non-uniform field having at least one maximum along the length of the slot. The electric field produced is non-radiating and its strength diminishes exponentially above the slot.

Abstract: Chemical compounds resulting from the mixing of organosilanes and quinones in the presence of di-tert-butyl peroxide as a sensitizer, exhibit strong blue phosphorescence. These compounds are highly resistant to deterioration by heat and UV irradiation. The unique feature of enhanced phosphorescence quantum efficiency at high temperature makes these systems most suitable for solar pumped lasers which usually will operate at relatively high temperature.

Abstract: An S-band standing wave electron accelerator structure having a multiplicity of resonant accelerating cavities and resonant coupling cavities mounted sequentially in an alternating accelerating cavity-coupling cavity pattern along an accelerator axis, with adjacent cavities separated by a common wall. The common walls and end walls of the structure have beam holes concentric with the axis, and the common walls further have two slots for coupling energy between the cavities. To prevent direct coupling between the accelerating cavities which are separated by a coupling cavity, the coupling slots in one wall of the coupling cavity are rotated approximately 90.degree. about the accelerator axis with respect to the coupling slos in the other wall. The structure is assembled by brazing a number of conductive segments together. Each segment forms half of each of the adjacent cavities having the common wall and thus consists of half of an accelerating cavity and half of a coupling cavity.

Abstract: The precision measuring amplifier includes one or more amplifiers, a number of fixed attenuators, a RMS detector and a logarithmic converter for converting the output of the RMS detector to a logarithmic value. A number of fixed voltage sources each providing a voltage precisely related to the attenuation of a corresponding attenuator, are selectively coupled to a summing amplifier to which the logarithmic converter output is also connected. The number of attenuators connected either manually or automatically into amplifier apparatus at one time is dependent on the input signal level, and for every attenuator connected into the amplifier apparatus, a voltage source is connected to the summing amplifier to provide an output signal proportional to the logarithm of the RMS value of the input signal.

Abstract: Apparatus for thermal spraying powdered material onto a substrate. The apparatus consists of an elongated conductive tube, an electrode positioned coaxially within one end of the tube. Inert gas such as helium is mixed with a powdered material such as a ceramic or a metal and a controlled amount is injected evenly into the tube. A high energy pulse is applied between the electrode and the conductive tube to produce current sheets which move from one end of the electrode to the other forming a high temperature and velocity plasma for melting and discharging the powdered material at a high velocity from the other end of the tube.

Abstract: A point-to-point high frequency communications system has a first set of frequency channels for transmission between a first terminal and a second terminal, and a second set of frequency channels for transmission between the second terminal and the first terminal. The channel evaluation apparatus includes a sounding transmitter and receiver at each terminal. These equipments operate in parallel with the regular communications system and provide the facility for real-time evaluation of all assigned channels using a sampling technique. Each sounding transmitter periodically transmits sounding signals in time-step sequence through its respective frequency channels to the sounding receiver at the other terminal. The sounding signals for each channel are evaluated for transmission quality and this information is displayed.

Abstract: An adaptive delta modulation system wherein the input analog signal is periodically sampled and a binary bit is generated for each period, the logic level of the binary bit being dependent on whether the sampled signal is greater or smaller than the approximate signal of the previous sample. Decoding apparatus converts the stream of binary bits to approximate the analog signal by periodically charging or discharging a capacitor integrator by predetermined variable steps. The charging or discharging of the integrator during each period is determined by the logic level of the binary bits, whereas the increase or decrease in step size for successive periods is determined by successive similar signal binary bits or successive dissimilar bits, respectively. The increase or decrease in step size is achieved by storing a binary step size number S in a register and adding or subtracting a fraction of the number to or from itself during each period, producing a new step size number for each period.

Abstract: The voice processing system for radio telephone consists of a compressor in the transmitter and an expander in the receiver. The compressor divides the input voice signal into syllabic groups and applies a gain to each syllabic group depending on the peak amplitude of the signal of the respective group, resulting in a reduction or compression of the dynamic range of the voice. The expander on the other hand increases or expands the dynamic range of the signal restoring the voice to its original form. The compressor and expander are synchronized such that the amount of expansion or instantaneous gain in the receiver is exactly the reciprocal of the amount of compression in the transmitter, i.e. when the gain of the compressor is N, the gain of the expander is 1/N. In this way the total system gain is always unity and is therefore transparent to voice and other analog signals passing through it.

Abstract: The ultrasonic air data system determines the relative velocity of an aircraft with respect to the medium in one, two or three directions. In addition, it may determine the speed of sound and the approximate temperature. In the one direction system, a first ultrasonic transducer transmits a pulse to a second transducer where it is detected and reflected back to the first transducer and again reflected to the second transducer. The pulse transmit times for each direction are determined, and the relative velocity, the speed of sound and the approximate temperature are provided as a function of the transit time. In the two or three direction systems, three or four transducers are positioned in a two or three dimensional configuration. In the first half cycle, the first transducer transmits a pulse to the second where it is reflected to the third or last transducer in a two-dimension system and then to the last transducer in a three-dimension system.