Showing papers by "Raytheon published in 1985"

Multirate digital signal processing

Abstract: There has been a great deal of material in the area of discrete-time transforms that has been published in recent years. This book does an excellent job of presenting important aspects of such material in a clear manner. The book has 11 chapters and a very useful appendix. Seven of these chapters are essentially devoted to the Fourier series/transform, discrete Fourier transform, fast Fourier transform (FFT), and applications of the FFT in the area of spectral estimation. Chapters 8 through 10 deal with many other discrete-time transforms and algorithms to compute them. Of these transforms, the KarhunenLoeve, the discrete cosine, and the Walsh-Hadamard transform are perhaps the most well-known. A lucid discussion of number theoretic transforms i5 presented in Chapter 11. This reviewer feels that the authors have done a fine job of compiling the pertinent material and presenting it in a concise and clear manner. There are a number of problems at the end of each chapter, an appreciable number of which are challenging. The authors have included a comprehensive set of references at the end of the book. In brief, this book is a valuable contribution to the general areas of signal processing and communications. It can be used for a graduate level course in perhaps two ways. One would be to cover the first seven chapters in great detail. The other would be to cover the whole book by focussing on different topics in a selective manner. This book by Elliott and Rao is extremely useful to researchers/engineers who are working in the areas of signal processing and communications. It i s also an excellent reference book, and hence a valuable addition to one’s library

Adder/substractor for variable length numbers

Abstract: An adder/subtractor wherein N/2 two bit adders are connected to allow the addition of numbers having N bits, each one of the two bit adders having associated control circuitry adapted: (a) to cause each two bit adder either to add applied bits directly or to add one applied bit and the "two's complement" of the other bit; and (b) to electrically separate any selected ones of the two bit adders from the others.

Track Biases and Coalescence with Probabilistic Data Association

Abstract: It is shown that probabilistic data association yields biased tracks in a multitarget environment, and the magnitude of the bias is investigated. A critical target separation distance exists, within which the tracks tend to coalesce completely. The problem of track initiation on new targets is also discussed.

Precision pointing using a dual-wedge scanner.

Abstract: A system was developed for calibrating and precisely pointing a germanium dual-wedge scanner for a CO2 Doppler lidar from an airborne platform. The equations implemented in pointing the scanner and those in the iterative calibration program, which combines available data with estimated parameters of the scanner orientation relative to the axes of the aircraft's inertial navigation system to arrive at corrected scanner parameters are described. The effect of specific error conditions on program performance and the results of the program when used on 1981 test data are investigated.

Asynchronous data clock generator

Abstract: A circuit and method for generating a substantially smooth clock for clocking asynchronous data to a user device. Incoming asynchronous data is stored in an elastic buffer such as a first-in first-out memory. Periodically, an output identifiable bit is read into the memory and a multibit digital signal corresponding to the number of output clock pulses for it to be read out is determined. This signal, which corresponds to the occupancy of the first-in first-out memory, is used to generate an analog voltage which controls a voltage controlled oscillator that provides the substantially smooth clock for reading data out of the first-in first-out memory. The control loop causes the long term rate of the smooth clock to be substantially equal to the incoming asynchronous data rate.

Fiber optic beam delivery system for high-power laser

Abstract: A system is provided for delivering a high-power laser beam through a fiber optic cable to a metal workpiece for drilling, cutting or welding the workpiece. The laser beam is focused onto a first end of the fiber optic cable, with a gas being applied to the first end of the cable as a cooling agent. The gas is transmitted coaxially with the fiber optic cable along the length thereof. The laser beam emerges from a second end of the fiber optic cable and is received and focused onto a workpiece by a beam delivery assembly. The transmitted gas is applied to the second end of the fiber optic cable as a cooling agent and injected onto the workpiece coaxially with the focused laser beam. With such arrangement, a laser beam is delivered to a workpiece for processing the workpiece via a flexible system, allowing the beam to be dexterously maneuvered about the workpiece. Also, since the gas cooling agent is applied to the workpiece coaxially with the focused beam, the gas may comprise an element which assists the laser beam in processing the workpiece. Also included is a mechanism for facilitating connection of the beam delivery assembly to an arm for maneuvering the beam delivery assembly through a plurality of positions with respect to the workpiece. Such mechanism inhibits rotation of the beam delivery assembly and the fiber optic cable during such maneuvering, thus preventing rotational strain from being applied to the cable and reducing the possibility of cable breakage.

Method of forming isolated device regions by selective successive etching of composite masking layers and semiconductor material prior to ion implantation

Abstract: A method for forming isolation regions in a semiconductor structure is provided. A mask comprising an upper and a lower layer of different materials is provided over the surface of the structure. A window is formed in the upper layer over the portions of the structure wherein the isolation regions are to be provided. Using the window in the upper layer as a mask, a larger window is formed in the lower layer by bringing a chemical etchant which etches only the lower layer into contact with the portions of the lower layer exposed by the window in the upper layer. The larger window formed in the lower layer is used as an etching mask to form an isolation groove, or depression, in the underlying semiconductor structure. The upper layer having the smaller window is used as an ion implantation mask for implanting particles into the bottom portion of the groove while masking the side portions of the grooves from the ions. With such method, lateral oxidation regions having self-registered anti-inversion regions which are located under the bottoms of the isolation regions and are spaced from the peripheries of the isolation regions by uniform, predetermined distances are obtained.

Line-of-sight reconstruction for faster homing guidance

Abstract: A novel way to generate the signal required for homing guidance is to reconstruct the line of sight angle by combining seeker boresi ht error with an integrated rate gyro signal (1.2,3,1,5). The paper shows that line-of-sight (LQS) reconstruction allows reduced stabilization loop gain requirements over other guidance implementations. For a given stabilization loop gain, faster guidance system time constants can be achieved with LQS reconstruction, thus enabling the guidance system to achieve more accurate hominq than other implementations.

Apparatus and method for frequency modulation

Abstract: A method and apparatus for frequency modulating a continuous wave signal is shown to comprise a voltage-controlled oscillator (VCO) having a first and a second control loop to maintain the carrier frequency of such VCO at a frequency determined by a crystal-controlled oscillator and to maintain the peak deviation of the FM modulation on such carrier frequency at a value equal to the deviation of the first Bessel null from the carrier frequency.

Compliant layer printed circuit board

Abstract: A printed circuit board having a compliant layer sandwiched between a pattern of conductors and an insulating layer. The printed circuit board has leadless chip carriers attached to soldering pads on the board using conventional soldering techniques. The elasticity of the compliant layer between the pattern of conductors and the insulating layer provides mechanical decoupling for minimizing stresses on the solder joints due to the different thermal coefficients of expansion of contiguous materials.

Adaptive beam forming apparatus

Abstract: A beam forming apparatus is provided having a plurality of beam ports producing a corresponding plurality of differently directed beams, each one of such beams being associated with a corresponding one of the beam ports, one of such beams being directed at a desired signal source and at least one of the beams being directed at an interfering signal source. A processor is coupled to the beam ports, for combining signals at such beam ports into a composite signal with the ratio of the power of the desired signal component of such composite signal to the power of the interfering signal component of such composite signal being increased from the ratio of the power in such desired and interfering signal components at the one of the beam ports associated with the beam directed at the desired signal source. The beam forming apparatus directs one of the beams at a desired signal source and an additional beam at each one of a number of interfering signal sources. The signals within the additional beams are weighted and then subtracted from the signals in the desired signal directed beam to substantially cancel the interfering signals from the desired signal. The number of weights required for computation is equal to the desired signal port plus the number of additional beam ports; i.e., one plus the number of interfering signal sources.

Calculation of the acoustic material signature of a layered solid

Abstract: A theory is presented for the calculation of the acoustic material signature of a multilayered elastic half‐space overlain by a fluid The solid layers are composed of homogeneous isotropic linearly elastic materials and are firmly bonded at the interfaces The calculation procedure is valid at an arbitrarily high frequency of excitation Results are presented for a uniform, a single layered and a four layered model of the half‐space at two frequencies of excitation; one moderate (35 MHz) and the other relatively high (370 MHz) Several new features of the material signatures and their possible use in the material characterization of layered specimen are indicated

Transmit/receive switch

Abstract: A transceiver transmit/receive (T/R) switching arrangement for electrically decoupling the transceiver's receiver circuit from first and second transceiver ports during transmission, and for electrically decoupling the transceiver's transmitter circuit from the first and second transceiver ports during reception Each such circuit includes an amplifier for amplifying an applied microwave signal and operating with a relatively high output impedance when power is applied thereto Each amplifier is inhibited from amplifying an applied microwave signal when power is removed therefrom First bias means switchably applies power to the transmitter amplifier during transmission and removes power from the transmitter amplifier during reception to switch the relatively high output impedance of such amplifier to a relatively low output impedance Second bias means switchably applies power to the receiver amplifier during reception and removes power from the receiver amplifier during transmission to switch the relatively high output impedance of such amplifier to a relatively low output impedance Additional circuitry in the transmitter circuit couples the amplified microwave signal from the transmitter amplifier to the second transceiver port during transmission, and transforms the relatively low output impedance of the transmitter amplifier to a relatively high impedance at the second transceiver port during reception Similar circuitry in the receiver circuit couples the amplified microwave signal from the receiver amplifier to the first transceiver port during reception, and transforms the relatively low output impedance of the receiver amplifier to a relatively high impedance at the first transceiver port during transmission

Laser hardened missile casing

Abstract: A thermally protective covering for a structure includes a thermally ablating layer comprising a nonporous ablative material comprising pyrolytic graphite or carbon composites bonded to a rigid, nonporous insulating layer comprising composites having high strength fibers in an insulating matrix. The insulating layer is bonded to the casing of the structural element to be protected. More preferably, the thermally ablating layer comprises pyrolytic graphite and the rigid, nonporous insulating member comprises silica phenolic. The ablating layer is bonded to the insulating layer with a high temperature graphite cement having adhesive properties to at least 3000° K. In a preferred embodiment, means are provided for venting pyrolysis gas produced during exposure of the ablating layer to a high energy laser.

Faraday Loss for L-Band Radar and Communications Systems

Abstract: The mechanism of Faraday rotation as it affects radar and communication propagation has been extensively treated (1, 7). The purpose of this paper is to point out the magnitude of the effect and its possible consequences which have not been appreciated. Contrary to what many believe, the two-way Faraday rotation angle and loss can be large at L-band for ground-based, linearly polarized radar systems observing targets above the ionosphere. Similarly, the one-way Faraday rotation and loss for linearly polarized, ground-to-space pace communication links at comparable frequencies can be large. The magnitude of the rotation loss depends on the location of the radar or communication station in latitude and longitude, the condition of the ionosphere, and the elevation and azimuth angles of the target. For example, based on the total electron content in 1970 (a peak sunspot activity year) at L-band, a two-way Faraday rotation greater than 50°a loss greater than 3.8 dB is calculated to occur at 60° N, 70° W, 75 percent of the time between the hours of 10 A.M. and 4 P.M. for nine months, and 22 percent of the total time for the entire year, when looking toward the south magnetic pole at low elevation angles. For the same year this rotation and loss at 15°N, 150° is calculated to occur 48 percent of the total time when looking south at low elevation angles.

The Multioscillator Ring Laser Gyroscope

Abstract: The multioscillator (or four-frequency) ring laser gyroscope is discussed from both a theoretical and a practical point of view. Fundamentals of device operation are presented, important nonideal behaviors (error sources) are discussed and analyzed from first principles, typical multioscillator gyroscopes are described, and samples of representative data from developmental instruments in our laboratories are reviewed. A key to the development of practical multioscillator instruments has been the introduction of nonplanar ring resonators. The theoretical formalisms (geometric and wave optic) necessary for understanding the properties of nonplanar ring resonators, and nonplanar gyroscopes, are derived and discussed in detail. Much of the material presented is new.

Radar system with incremental automatic gain control

Abstract: A radar receiver having a feed-forward control circuit for adjusting the automatic gain control (AGC) setting in 6 dB increments for each range cell in a next sweep based on the AGC setting of each corresponding range cell in the present sweep, the magnitude of the larger of the in-phase (I) or quadrature (Q) components of the video signals of the present sweep from an A/D converter, the status of present sweep and previous sweep A/D limit conditions, and a selected guardband thereby holding the level of the radar return signal within the dynamic range of the A/D converter. The AGC setting is adjusted using a switchable attenuator which changes the level of the video signal into the A/D converter in 6 dB increments, each increment corresponding to a common I and Q data exponent directly used for floating point signal processing. A pulse interference detection and signal replacement apparatus and method utilizes an 8-bit log magnitude representation of each range cell sample generated from a floating point exponent and reduced precision mantissa components to detect a range cell pulse of interference at a specific range M and causes replacement of the range cell sample with an interpolated value determined from the average of the radar return signals of adjacent sweeps at range M.

Gas oven with recessed broil burner

Abstract: A gas oven having a broil burner recessed up into a chamber above the ceiling to provide more usable space in the oven cavity A partition closely above or extending from the sides of the burner forms an upper chamber duct which extends from an exhaust flue at the rear to a passageway to the cavity at the front of the chamber The products of combustion from the burner flow forwardly in lateral troughs to the passageway where they mix with other cavity vapors and then rearwardly in the duct to the exhaust flue The duct functions to reduce the body temperature of the burner to prevent flashback and also enhances stack action

Low voltage amplifier circuit

Abstract: An electronic circuit is provided comprising: a pair of transistors having collector electrodes connected together at an output terminal and emitter electrodes coupled to opposite potentials of a voltage supply; a current source; and, means, responsive to a current produced by the current source, for establishing bias currents to base electrodes of the pair of transistors in accordance with an input signal, such bias currents being dependent on the current produced by the current source and being substantially independent of, over a nominal operating supply voltage range of the circuit, of variations in the voltage supply. With such arrangement, since the bias current to the transistors are provided from a current source, the bias currents are independent of the voltage supply and the circuit may operate with less than a one volt voltage supply. In accordance with a preferred embodiment of the invention, a resistor is coupled between the voltage supply and an emitter of one of the pair of transistors. With such arrangement current gain is provided. Further, the supply voltage may be as low as 2V CE (SAT) +IR where IR is the voltage drop across the resistor, typically 30 millivolts. Hence, the minimum supply voltage is still less than one volt.

Configurable analog integrated circuit

Abstract: An integrated circuit comprising a plurality of gain cells interspersed with a plurality of passive and active, electrically isolated components (e.g. thin-film binarily-weighted resistors and transistors). Each gain cell comprises a differential amplifier gain stage comprising a pair of emitter-coupled transistors, the coupled emitters being connected to a current source. The collectors thereof are coupled to a pair of transistors configured as a current mirror. The emitter-coupled transistors, current source and current-mirror transistors are disposed on a first level of the integrated circuit. A first output stage comprising a common-emitter transistor and a second output stage comprising a transistor having an electrically isolated emitter are disposed on the first level. An upper level of metallization is used for selectively coupling either: the output of the differential amplifier gain stage to the first output stage, thereby configuring the gain cell as a comparator; or, additionally, the second output stage transistor between the collector of the first output stage transistor and the output of the differential amplifier, thereby providing an operational amplifier circuit configuration. With such arrangement, each gain cell has a pre-configured gain stage with predetermined electrical characteristics. The manufacturer may then configure each gain cell as either an analog comparator or an operational amplifier having well-defined electrical characteristics during the final metallization process. The gain cells and passive and active components further are selectively interconnected by second level metallization to thereby configure a desired circuit.

Determination of sin2 theta W and rho in deep-inelastic neutrino-nucleon scattering.

Abstract: We have determined the electroweak parameters ${{sin}^{2}\ensuremath{\theta}}_{\mathrm{W}}$ and $\ensuremath{\rho}$ by a measurement of deep-inelastic neutrino-nucleon scattering used a fine-grained neutrino detector exposed to a narrowband neutrino beam at Fermilab. The sampling properties of our detector have permitted neutralcurrent and charged-current events to be well separated over a wide kinematic range, thereby allowing a determination of ${{sin}^{2}\ensuremath{\theta}}_{\mathrm{W}}$ and $\ensuremath{\rho}$ to be made with good statistics and small systematic errors. We have found ${{sin}^{2}\ensuremath{\theta}}_{\mathrm{W}}=0.246\ifmmode\pm\else\textpm\fi{}0.012\ifmmode\pm\else\textpm\fi{}0.013$ in a single-parameter fit.

Evaporated thick metal and airbridge interconnects and method of manufacture

Abstract: A first masking layer of a first resist is provided over a semiconductor substrate and is patterned in a selected region to provide a masked region over which an airbridge interconnect will be provided. A second relatively thick layer of a second, different type of resist and a third relatively thin layer of resist are provided, respectively, over the substrate. The second and third layers of resist are patterned to provide an aperture having overhanging portions exposing the previously applied patterned regions of the first layer, and selected adjacent portions of the substrate. The second and third layers may also be patterned to provide a region for a patterned strip conductor. A stream of evaporated metal is directed towards the substrate and deposited within the apertures to provide an airbridge interconnect conductor and patterned strip conductor. The overhanging portions of the apertures provide separation between the metal layer deposited within the aperture and the metal layer deposited over the third masking layer, allowing the second and third masking layers to be lifted-off without disturbing the conductors. The masked regions underlying the bridges are also removed leaving the airbridge interconnect and patterned strip conductor.

Upper bound on the τ-neutrino mass from the previously unobserved decay mode τ→KKπντ

Abstract: We report a measurement of the branching ratios for two decay modes of the tau lepton: R/sub B/(tau/sup + -/-->K/sup + -/K/sup - +/pi/sup + -/nu/sub tau/) = (022/sub -011//sup +017/)% and R/sub B/(tau/sup + -/-->k/sup + -/pi/sup - +/pi/sup + -/(pi/sup 0/ )nu/sub tau/) = (022/sub -013//sup +016/)% The separation of these channels is accomplished in the DELCO detector by use of a gas Cerenkov counter to identify fast kaons The invariant-mass distribution of the k/sup + -/K/sup - +/pi/sup + -/ system has been used to set an upper bound on the tau neutrino mass of 157 MeV at 95% confidence level

Raster display system

Abstract: An echo receiving system is provided for periodically scanning a region for echo returns obtained in polar coordinates and for providing a visual display of such received echo returns in a rectangular raster format, such system comprising: a scan converter, responsive to the echo returns obtained in polar coordinates for converting such returns into rectangular coordinates; and, means for modifying such coordinate converted returns and for displaying such modified, coordinate converted returns in the rectangular raster format with displayed data being a function of the scan-to-scan change in echo returns from objects in the second region. With such arrangment, target build-up and target decay may be presented in the digitally generated raster display in a manner similar to that presented in an analog PPI display.

Dual mode target seeking system

Abstract: A dual mode target seeking system for airborne vehicles which operates under two different frequencies simultaneously includes a radio frequency antenna comprising a slotted plate defining a ground plane with an image plate positioned in front of the ground plane at a distance chosen such that multiple reflected rays are in phase with each other and with waves incident on the image plate. The slotted plate and image plate have aligned central openings through which an electro-optical system for operating under a chosen electro-optical frequency range, for example under infrared frequencies, projects. The electro-optical system includes a detector unit positioned behind the antenna and a focussing system for directing incoming electro-optical radiation into the detector unit. The focussing system includes first and second lenses mounted in the openings in the image plate and slotted plate, respectively. The lenses each transmit radiation in the chosen electro-optical frequency range while at least partially reflecting radio frequency radiation.

A new nonlinear filtering formula for discrete time measurements

Abstract: An exact formula for computing the conditional mean of a random variable is derived for discrete time observations. This formula is analogous to the well-known result of Fujisaki-Kallianpur-Kunita for continuous time observations, and it is similar to the discrete time formula recently derived by Takeuchi and Akashi. The derivation of the new formula is extremely elementary, and it is based on the judicious choice of a certain homotopy function.

Quick-disconnect waveguide connector assembly

Abstract: A quick connect/disconnect waveguide connector assembly is provided comprising first and second mating waveguide connectors. The first mating waveguide connector comprises a first outer member and a first insert disposed within the first outer member. The first insert has a mating portion having a generally conical shape truncated at a first face. The first insert further includes a waveguide slot disposed therethrough and intersecting the first face. The second mating waveguide connector comprises a second insert having a complementary mating portion. Such mating portion has a generally conical-shaped cavity therein truncated at a second face. The second insert further has a waveguide slot disposed therethrough and intersecting the second face. The second mating waveguide connector further comprises a second outer member rotatably mounted about the second insert. The first and second inserts include means for aligning the waveguide slots disposed therethrough with the waveguide slots having the same angular orientation about a common axis, upon mating the first and second inserts at the first and second mating portions thereof to engage the first and second faces thereof. The first and second outer members include means for locking the second outer member to the first outer member and maintaining the mating of the first and second inserts by rotating the second outer member about the first outer member through only a portion of a full turn.

Log magnitude pulse interference detection for a radar system

Abstract: A radar receiver having a feed-forward control circuit for adjusting the automatic gain control (AGC) setting in 6 dB increments for each range cell in a next sweep based on the AGC setting of each corresponding range cell in the present sweep, the magnitude of the larger of the in-phase (I) or quadrature (Q) components of the video signals of the present sweep from an A/D converter, the status of present sweep and previous sweep A/D limit conditions, and a selected guardband thereby holding the level of the radar return signal within the dynamic range of the A/D converter. The AGC setting is adjusted using a switchable attenuator which changes the level of the video signal into the A/D converter in 6 dB increments, each increment corresponding to a common I and Q data exponent directly used for floating point signal processing. A pulse interference detection and signal replacement apparatus and method utilizes an 8-bit log magnitude representation of each range cell sample generated from a floating point exponent and reduced precision mantissa components to detect a range cell pulse of interference at a specific range M and causes replacement of the range cell sample with an interpolated value determined from the average of the radar return signals of adjacent sweeps at range M.

Low-resistance ohmic contacts to p-type GaAs using Zn/Pd/Au metallization

Abstract: We have fabricated the low resistance ohmic contacts to p-type GaAs. Specific contact resistances as low as 7 × 10-7Ω.cm2have been obtained for contacts prepared by heat treating Zn/Pd/Au metallizations deposited on p-type epitaxial GaAs layers with an acceptor concentration of 1.5 × 1019cm-3. These contacts are reproducible, simple to fabricate, exhibit excellent adhesion, and have a uniformly smooth surface morphology.