Abstract: An arrangement for testing the performance of an electronic system utilizing a phased array antenna as its principal radiator into a predetermined sector of space includes, as one of its main components, an enclosure which bounds a miniature anechoic chamber located in the near-field region of the antenna array during the performance of a testing operation and lined with material that absorbs free space electromagnetic radiation. The enclosure has an opening that is aligned with the phased array antenna the performance of which is being tested. Two dual-polarized testing horn antennas are situated at a wall of the enclosure that is opposite to the wall provided with the opening. Electrical signals received from the horn antennas and representative of the near-field electromagnetic radiation emitted by the phased array antenna are supplied to an evaluating circuit which gives indication of the performance of the electronic system of the phased array antenna.

Abstract: A receiving modem is locked to a transmitting modem by employing a burst data and clock signal having an effective data rate compatible with the data rate of a receiving data set. The receive modem processes a transmitted analog signal as sent by the transmitting modem to provide a digital signal which is applied to an interpolation filter. The filter provides at an output a retimed signal. This retimed signal is monitored by a baud sync measurement circuit which detects the drift of baud transitions in the retimed interpolated signal to provide an output phase error signal. This phase error signal is used to control the filter coefficients of the interpolation filter for the next data block. In this manner the interpolation filter provides a newly retimed digital output signal according to the detected phase error. The output signal is demodulated and converted to a burst data and a burst clock signal for application to a receiving data set.

Abstract: A microchannel electron multiplier is formed by placing into a glass tube a plurality of bundles optical fibers, each having an etchable glass core and a glass cladding which is non-etchable when subjected to the conditions used for etching the core material. The fiber bundles located around the inside edge of the glass tube are replaced by support fibers having both a core and a cladding of a material which is non-etchable under the above-described conditions. The assembly of the tube, bundles and support fibers is heated to fuse the tube, bundles and support fibers together. The etchable core material is then removed and the assembly sliced into wafers. The inner surface of each of the claddings which bound the channel formed after removal of the core material is rendered electron emissive by reduction of the lead oxide by hydrogen gas. Metal films are deposited onto the opposed surfaces of each of the wafers to form contacts.

Abstract: An image intensifier tube and a method of making same are disclosed wherein veiling glare caused by the amplification of off axis light is reduced. Included is a non-reflective, near infrared light absorbing first layer formed on the face plate of the tube adjacent any surface at which off-axis light could otherwise be reflected to the photoemissive device associated with the face plate and an electronically conductive second layer formed on top of the first layer. Such coatings are preferably formed by sputter deposition.

Abstract: Electronic priority map storage and control for prioritizing radar detections for fire control or monitoring purposes relative to batteries of mortars or artillery or other projectile sources. Use of a priority map to increase probability of location of at least one weapon in each battery is desired. The theory is based upon the premise that all guns in a battery are firing at the same target and, consequently, all projectiles from a battery will be detected within a relatively small area. By distributing track initiations over a large area of detection, the probability of tracking projectiles from all batteries is increased. The use of the priority map to accomplish this function is made in order to save time in a general purpose data processing computer employed additionally for other functions. A group of priority map cells are combined to form a track initiation cell. That is, a second map is formed with coarser granularity for the purpose of controlling the priority of track initiations.

Abstract: A process for manufacturing GaAs FET's having refractory metal gates provides for reducing the size of the gate relative to a mask by an etch sequence which results in precisely controlled and repeatable self-limited undercutting of the mask. A reactive ion etch of the refractory metal in a CF.sub.4 O.sub.2 plasma containing an inert gas provides the self-limiting undercut at a pressure in the range of 175-250 mTorr when the power is less than 0.15 W/cm.sup.2. Preceeding the undercut, an anisotropic RIE in a CF.sub.4 plasma can be employed to clear unmasked areas of the refractory metal and an initial sputter cleaning in argon improves the quality of the initial etch.

Abstract: The provision of an intermediately doped transition region between respective n+ implanted source and drain regions in a GaAs FET and the lightly doped channel region under the gate permits device optimizaiton for low source and drain resistance in EFET's while employing the same n+ implant for source and drain optimization in DFET's while also maintaining the same n+ to gate contact spacing in both device types. Additionally, in high frequency operation of an asymmetrically implanted FET, the tapered doping profile offered by the transition region on the drain side of the gate provides high transconductance without sacrificing high output resistance. The transition region can be provided in a self-aligned implant employing dielectric sidewall spacers and the n+ implant can be self-aligned with an etch mask employed in gate definition.

Abstract: There is disclosed a high light level cutoff apparatus for use with night vision devices. The apparatus employs a digital method of timing implemented by a divider counter responsive to a crystal controlled input frequency which essentially controls a latch to produce an automatic shutoff of a night vision device during high light ambient conditions which conditions would undesirably reduce the effective life of such a night vision device. The circuitry disclosed utilizes a digital method of clocking and employs the latching relay as indicated which is operated by the digital counter. The circuitry provides a feed back from the latching relay which resets the night vision system so that it will re-operate if a transient accidentally serves to operate the goggles while the light level is in a high state.

Abstract: A digital-to-synchro converter is provided where a binary input code specifies a desired shaft angle and where an resolver type position transducer is employed with additional circuitry to generate a shaft position error signal indicative of the angular difference between the desired shaft angle and the actual shaft angle. The additional circuitry corrects for known and calculated errors in the shaft position detection process and equipment.

Abstract: An apparatus operates to identify the speech signal of an unknown speaker as one of a finite number of speakers. Each speaker is modeled and recognized with any example of their speech. The input to the system is analog speech and the output is a list of scores that measure how similar the input speaker is to each of the speakers whose models are stored in the system. The system includes front end processing means which is responsive to the speech signal to provide digitized samples of the speech signal at an output which are stored in a memory. The stored digitized samples are then retrieved and divided into frames. The frames are processed to provide a series of speech parameters indicative of the nature of the speech content in each of the frames.

Abstract: A digital divider with both integral and fractional division capabilities is provided by utilization of a counter and one decoder to trigger phase reversal and a second decoder to trigger short-cycling of the counter. The first decoder provides phase reversal to cause extra half pulses during the period established by the second decoder to thus create the fractional count needed for fractional division. A control input is included to select either whole number division or fractional division.

Abstract: A process for manufacturing gallium arsenide microwave circuits makes use of a nonphotosensitive acid resist as an adhesive for holding the "front side" of a gallium arsenide wafer onto a substrate while operations such as etching "via holes" into the wafer are being performed on the "back side" of the wafer. The process comprises front side processing, spinning the nonphotosensitive acid resist onto the frontside of the GaAs wafer, baking the protective acid resist coating onto the wafer, spinning the acid resist onto a substrate, joining the wafer to the substrate, thinning the wafer, and performing backside processing.

Abstract: A photo-detector in the form of an optical field effect transistor comprig a semi-insulating InP substrate (1), a p.sup.+InP gate region ( 2) an n.sup.- InGaAs channel region (3) and source and drain contacts (5,6). Light incident on the bottom face of the substrate is detected. The channel region is thicker and reduced in doping in comparison with a normal JFET in order to achieve efficient light absorption and low gate to source capacitance. The source and drain contacts are interdigitated to increase the area for optical absorption (FIG. 1). Alternatively, (FIG. 2), the channel region is a composite structure including a lowly doped layer (11) for directing photogenerated carriers to a more highly doped layer (12) (active channel layer) of reduced dimensions of reduced area and upon which strip-like source and drain contacts (9,10) are disposed. The optical FET structures proposed facilitate integration with other circuit elements.

Abstract: A solid state radar transmitter pulse modulator system capable of generating high power operating pulses having pulse width and pulse repetition rate agility and being programmable for output pulse current over a substantial range of peak current values to produce corresponding values of transmitter output power. A multi-stage cascade cross-field amplifier (CFA RF chain) is employed, each stage having its own pulse modulator comprised of one or more standard modules paralleled at the output to drive the corresponding CFA stage provides fail-soft operation. Means are included for protecting solid state circuits in the event of CFA or other component failures, for dynamically matching CFA and pulse transformer impedances, and for preventing BH curve "walk-up" during operation.

Abstract: A high voltage pulse clipper for stabilizing the amplitude of successive pulses applied, for example, as modulator pulses to a microwave transmitter. A source of such pulses has its output connected across a capacitor through a series diode whereby the capacitor charge acts as a back bias for the diode. The ground potential side of the capacitor includes a circuit which adds a voltage in opposition to that extant across the capacitor to equalize the capacitor error voltage resulting from variations of the input pulse amplitude and pulse spacing.

Abstract: There is disclosed a small arms sight assembly which enables a firearm such as a revolver or rifle to be employed for both nighttime and daytime use. The gun sight assembly includes a typical telescopic sight assembly of a conventional design which sight assembly includes an image intensifier module which can be selectively removed from the telescopic sight. The intensifier module or assembly when employed in conjunction with the remaining sight components enables the user to operate the weapon under low light conditions. During daytime operation the intensifier module housing section is removed. In this manner there is described a sight which enables a small weapon to be employed for daytime or nighttime use while providing increased effective weapon range when compared to conventional sight devices.

Abstract: A liquid crystal beam splitter includes a magnetic coil adapted to controllably orient, or tilt, the molecules of a layer of liquid crystal material and thereby detune the internal reflections of a polarized light beam component passing therethrough.

Abstract: A method and structure are disclosed for mounting and connecting an electic device such as an integrated circuit to a circuit board. The board has a plurality of embedded shielded conductors for interconnecting the integrated circuit to other devices on the board. In order to limit the capacitance and inductance of the connection, the integrated circuit is mass bonded directly to the conductors and to their coaxial shields.

Abstract: A liquid crystal wave division device includes first and second polarization changing cells, the polarization changing cells utilize homogeneously aligned nematic liquid crystal material to effect the change of polarization of a preselected frequency portion of a multifrequency incident light beam.

Abstract: The variable directional coupler of the subject invention employs 3, 4 or n branches in TEM transmission media, such as coax, stripline and microstrip. Precise control of the coupling is acheived by a variable susceptance connected near the mid-point of the crossover.