Abstract: A clocked first-in first-out (FIFO) memory includes interleaved dual-port static random access memories (SRAM's) 32 and 36. The FIFO has status flags 44 to indicate empty and full conditions and two programmable flags, almost full and almost empty, to indicate when a selected number of words is stored in memory. In accordance with the present invention, the FIFO has retransmit capability, allowing previously read data to be accessed again. The FIFO is put in retransmit mode by providing a retransmit mode (RTM) input signal. This event causes the current read address stored in the read address registers 52 and 54, the interleave status in toggle circuit 22, the data in the data output latches 18 and 20 and in the pipeline latch 42, and the status flags 44, to be saved in shadow registers 64, 66, 24, (30, 62, 70, 116 and 120.

Abstract: A digital speech-band spectrum inversion apparatus for use in a cordless telephone system provides transmission security of the voice signal between the handset (10) and the base station (18). The apparatus includes an A/D converter (24) for converting an input analog voice-band signal to a digital signal, a digital signal processor (30) for modifying the digital signal in accordance with a prescribed algorithm, and a D/A converter (32) for converting the modified digital signal to an output analog signal, the output analog signal being inverted in frequency spectrum from the input analog signal. A/D converter (24) samples the input analog signal at a periodic rate, and converts the sampled voltage levels to digital representations thereof. The algorithm performed by the digital signal processor (30) computes the two's complement inversion of the digital representations of alternate samples of the input analog signal.

Abstract: Reaction gases are prevented from escaping from a reaction chamber through the use of flexible or gas seals between the interface of the reaction chamber and the junction used to connected successive reaction chambers.

Abstract: A device (10) for controlling current through a circuit has an antifuse material (18) separating a first conductor (12) and a second conductor (20). An insulating element (14) and another insulating element (16) further separate the first conductor (12) from the second conductor (20). The antifuse material (18) includes a dopant which raises the band gap and seals off paths in grain boundaries of the antifuse material (18) in order to limit leakage current from flowing between the first conductor (12) and the second conductor (20). When an interconnection is desired, a high voltage pulse is applied across the first conductor (12) and the second conductor (20) to initially break down the antifuse material (18). The breakdown of the antifuse material (18) causes a filament (22) to form between the first conductor (12) and the second conductor (20). The filament (22) creates a conduction path connecting the first conductor (12) and the second conductor (20) electrically together.

Abstract: A technique is described for improving the sampled current accuracy in current mirror circuits such as are often used to monitor the current output to a load. A reference voltage is established to feedback the load voltage conditions at the output to the current reference circuitry, thereby greatly reducing the error in the reference current over that which is produced by prior art circuits. The technique is shown as applied to a current limiting circuit for driving an output load. An alternative embodiment is also disclosed.

Abstract: A laser radar system for measuring wind velocities including apparatus for permitting the system to measure the direction of the atmospheric flow field. A modulator is used to chirp the laser frequency toward increasing frequencies. The local oscillator frequency available for homodyning will be offset from the initial transmitted frequency by an amount equal to the chirp rate multiplied by the round trip transit time to the aerosols at the focal point of the converging laser beam. During the up-ramped chirps of the optical beam frequency, the Doppler shift frequency of aerosols moving toward the laser beam will be translated to a lower frequency, and the Doppler shift frequency of aerosols moving away from the laser beam will be frequency translated upward.

Abstract: An optical beam steering device for use in a single-aperture laser transceiver system provides deflection of the transmitted and received beam in two planes, while maintaining the distinctive identities, of each channel respective to their polarizations. The invention utilizes four single-dimensional beam deflecting devices, two for each orthogonal linear polarization of the two transceiver channels, one of these for each steering axis. In addition, a 90.degree. polarization rotator and a quarter-wave plate are included in the arrangement of beam deflecting devices to satisfy the polarization requirements of these devices and of the transceiver channels.

Abstract: An interferometer for transmitting a beam of electromagnetic energy toward a target, portions of the transmitted beam reflected by the target being directed onto a detecting surface of a detector element with a local oscillator beam to provide a beat frequency signal representative of, for example, target range. The interferometer comprises a first lens for focusing the target-reflected return beam onto substantially a point on a detecting surface. The interferometer additionally comprises a second lens, for example, for focusing the local oscillator beam through a focal point onto the first lens. The first and second lenses are disposed to align such focal point of the second lens with a focal point of the first lens to thereby direct the local oscillator beam onto the detecting surface of the detector element with a substantially uniform intensity distribution thereon.

Abstract: An adaptive distortion cancellation algorithm minimizes intersymbol interference (ISI) when demodulating signals in the presence of distortion over fading and dispersive channels. The algorithm computes preliminary estimates of received data and feeds them to a canceller structure. The canceller checks the preliminary estimates and then makes a series of subsequent estimates by modifying the elements of the original received estimated data sequence. Each estimate generates a distortion cancellation quantity which is added to the received data estimate to generate a sequence of values; a final decision is determined by that subsequent estimate which is closest to an ideal state. The preliminary estimates are made using a conventional transversal filter whose coefficients are controlled by one of the existing filter tap algorithms.

Abstract: A field emission cathode for use in a cathode-ray tube (CRT) includes groups of electron emission cells that produce different degrees of luminance on the phosphor-coated CRT screen. The cells replace the conventional CRT cathode and are fabricated on a planar surface. Each cell comprises a fixed number of discrete electron emitters, and the groups comprise different numbers of cells, typically in binary relation to one another. The cell groups of are interconnected via separate drive lines; each group is activated by applying voltage to its line. Different combinations of groups may be activated to achieve different brightness intensities on the CRT screen. A cathode having fifteen cells arranged in four groups (1, 2, 4 and 8 cells) is capable of producing sixteen shades of gray.

Abstract: An apparatus is disposed for controlling the brightness of a matrix-addressed flat panel CRT display of a type having intersecting column and row conductors forming, respectively, the gate and cathode electrodes of a field electron emission array. The brightness control is effected by controlling both the duty cycle and the voltage applied to the drive lines of the intersecting conductors. A periodic staircase waveform having progressively increasing voltage steps is sequentially applied to the row conductors. The voltages at each of the steps are preferably selected to enable electron beam currents which provide brightness levels which are twice the brightness of the previous step. Binary-coded video brightness data are simultaneously applied to all of the column conductors. The combined voltages at the intersections of the selected conductors cause a sequence of electron emissions onto luminescing means which result in a corresponding sequence of illumination intervals.

Abstract: A sprayable ablative coating formulation comprises a combination of a polymeric resin, a curing agent, cork flour and a vehicle such as toluene. The mixture is sprayable using conventional spray equipment. The surface to be coated is first sprayed with a primer to improve adhesion, and the mixture is then sprayed over the primed surface until a desired thickness if formed. Once cured, the coating has a uniform fine texture and thickness, providing thermal insulation for the coated surface. Pigments may be added to the formulation to achieve specified coloration of the coating.

Abstract: A production circuit tuning tool consisting of a cover and a number of feed-through, gold-tipped probes that adjust the performance of an underlying circuit. The probes are positioned in the cover so that they may act as temporary jumpers between the trace wiring and tuning patches on the circuit substrate. The portion of the probe that bridges the patches comprises a slender nonconductive plunger of low dielectric constant material having a gold plated tip. Once the proper combination of jumpers is determined, the tuning tool cover is removed, permanent jumpers are soldered into place and a regular production cover is installed.

Abstract: A practical means for electrically addressing the extremely large number and high density of phase shifters needed for operation of an optical phased array beam steerer. The array of phase shifters is subdivided into identical subarrays which completely fill an optical aperture. All subarrays are connected electrically in parallel by electrically interconnecting corresponding electrodes of each subarray. Methods are disclosed herein for providing an enhanced number of beam steering positions for the subaperture-addressed beam steerer.

Abstract: A practical means for electrically addressing the extremely large number and high density of phase shifters needed for operation of an optical phased-array beam steerer. The array of phase shifters is divided into identical subarrays which completely fill an optical aperture. All subarrays are connected electrically in parallel by electrically interconnecting corresponding electrodes of each subarray. Thus, the number of external electrical leads required for addressing the full array is reduced to the number of phase shifters in a signle subarray.

Abstract: A procedure is disclosed for detecting and documenting flaws in the glassivation layer protecting the active device region of an integrated circuit. A droplet of dilute sulfuric acid solution is placed on top of the glassivation layer and a positively biased electrode is immersed in it. The leads coupled to circuit under the glassivation layer are coupled to a more negative voltage. The release of hydrogen bubbles into the solution through flaws in the glassivation via an electrolysis reaction are readily observable. Defects in a glassivation layer over nichrome devices may be documented by reversing the polarity of the bias to cause a reversal of the electrolysis process and a release of oxygen from the defective sites. This causes oxidation and disfigurement of the nichrome which can be documented using ordinary photographic means.

Abstract: A magnetic field sensing and canceling circuit for use with a cathode ray tube (CRT) has a closed loop system consisting of flux gate sensors to measure external magnetic fields and magnetic field cancellation coils around the perimeter of the faceplate of the CRT to cancel the fields and thus minimize color and positional ac image distortion. The coils are mounted on an enclosure fabricated of a high permeability material and are positioned around the perimeter of the CRT's faceplate. Four of the coils are parallel to the top, bottom, and sides of the enclosure opening and a fifth coil is wound around the enclosure adjacent the CRT faceplate. The magnetic flux gate sensors provide output signals that are functions of the detected fields. These signals control the current in the magetic field cancellation coils and thus control the cancellation fields.

Abstract: A laser is provided comprising a laser envelope and a gain medium disposed in the laser envelope. The gain medium comprises a compound subject to dissociation into a plurality of components. Circuitry is included for generating an electrical discharge in the laser envelope, a portion of the electrical discharge passing through the gain medium and disassociating a portion of the compound thereof into the plurality of components. The discharge generating circuitry comprises a cathode, the cathode comprising a first portion for emitting the electrical discharge toward an anode. Such first portion comprises a catalyst for aiding the recombination of the dissociated plurality of components. The first portion of the cathode sputters particulates therefrom during the electrical discharge and a surface is disposed within the laser envelope for collecting the sputtered particulates.

Abstract: A multiple band antenna feed used with parabolic reflector antennas and the like. The feed is arranged as two coaxially disposed waveguides. A planar array of patch elements is disposed at the end of the coaxial waveguides so the energy in each band radiates from a common phase center. This simplifies the arrangement of associated subreflectors.

Abstract: A radio frequency (RF) driven laser system having a starter electrode and discharge control circuitry which facilitates the starting of the laser by ionizing a portion of the gain medium. The starter electrode is aligned with the main electrode but is much smaller and is energized only during the start-up period. RF power is coupled to the main and starter electrodes via RF amplifiers feeding power through a 90.degree. hybrid combiner to impedance matching networks which are individually adjusted for each electrode. The matching network coupled to the starter electrode provides a very high, Tesla coil type, RF voltage to the electrode. Once the start cycle is complete, a time delay circuit shuts down the starter circuit and all power from the two RF amplifiers is steered to the main electrode.