Showing papers by "Raytheon published in 1983"

Decoupled Kalman filters for phased array radar tracking

Abstract: Kalman filters have been used in numerous phased array radars to track satellites, reentry vehicles, and missiles. This paper considers the design of these filters to reduce computational requirements, ill-conditioning, and the effects of nonlinearities. Several special coordinate systems used to represent the Kalman filter error covariance matrix are described. These covariance coordinates facilitate the approximate decoupling required for practical filter design. A tutorial discussion and analysis of ill-conditioning in Kalman filters is used to motivate these design considerations. This analysis also explains several well-known phenomena reported in the literature. In addition, a discussion of nonlinearities and methods to mitigate their ill effects is included.

2-20-GHz GaAs Traveling-Wave Power Amplifier

Abstract: Power amplification in FET traveling-wave amplifiers is examined, and the mechanisms which limit power capability of the amplifier are identified. Design considerations for power amplification are discussed. A novel single-stage and two-stage monolithic GaAs traveling-wave power amplifier with over 250-mW power output in the 2-20-GHz frequency range is described.

A review of the state-of-the-art of oil spill fate/behavior models

Abstract: The fate and behavior of spilled oil can be affected by nine physical, chemical, and biological processes: advection, spreading, evaporation, dissolution, emulsification, dispersion, auto-...

Multifrequency microwave source

Abstract: A frequency-agile source of microwave frequency signals is shown to include: a voltage-controlled oscillator operating within a band of microwave frequencies; a crystal-controlled oscillator operating at a frequency lower than the band of microwave frequencies and producing harmonics within such band; a phase detector having samples of the signals out of the crystal-controlled oscillator and the voltage-controlled oscillator applied as input signals; and a shaping amplifier receiving the output signal of the phase detector to provide a control signal related to the phase difference between the signal out of the voltage-controlled oscillator and the harmonic of the crystal-controlled oscillator nearest to the frequency of the voltage-controlled oscillator.

Continuous wave radar with ranging capability

Abstract: A frequency modulated continuous wave radar wherein analog signals received from a target are converted to digital form, processed by correlation with differently delayed signals, also in digital form, of a modulation waveform repetitively applied to the transmitted signals and the frequency spectra of the resulting signals are determined, such spectra being indicative of range of the target. In addition, a digital correlator adapted to perform the desired correlation is shown.

Missile guidance design tradeoffs for high-altitude air defense

Abstract: Practical design considerations for a high-altitude radar-guided air defense missile are presented. Three major contributors to miss distance are discussed—the radar signal return, the radar tracking seeker component imperfections, and the missile response limitations. At high altitude, glint may be the major contaminant in the radar signal. In addition, seeker component imperfections such as imperfect gimbal stabilization, radome refraction slope, and seeker gyro acceleration sensitivity cause stability and miss distance problems that the guidance system designer must solve. Finally, the missile response to guidance commands is limited by reduced acceleration capability, increased response time, and control fin rate saturation. The miss distance sensitivity of each of these factors is discussed and, in addition, the stability issues associated with the unwanted feedback paths created by component imperfections are addressed. Numerical examples are presented showing the significance of including practical hardware imperfections in preliminary design if performance goals at high altitude are to be met when the system is built. The paper provides a perspective of real-world problems which in theoretical investigations are often viewed as secondary issues, but which in fact may be the dominant factors that dictate the guidance and control system design parameters.

Measurement of series resistance in IMPATT diodes

Abstract: A new method is given for determining the electrical series resistance of an IMPATT diode. The measurement is based on observation of the oscillation threshold bias current for a diode in a standard circuit. The method is applied to GaAs diodes near 40 GHz. The values obtained are used to quantitatively explain other performance characteristics of the diodes.

Sputtering apparatus and methods

Abstract: A method of depositing material onto an object in an ionization chamber having a shutter therein which has an object-obscuring portion comprising the step of confining particles of matter deposited on the object-obscuring portion of the shutter to such object-obscuring portion while the object is being deposited with material. The object-obscuring portion of the shutter includes an open ended container, the open end thereof being formed in an upper portion of the shutter. During ionization a glow region is formed in the chamber separated from a source of the material by a dark space region. The upper surface of the shutter is disposed in the dark space region and the bottom of the container is separated from the source sufficiently to enable ionization. Prior to deposition of the material onto the object, the object-obscuring portion of the shutter is positioned between a source of the material and the object and contaminents on the surface of such source are removed therefrom and are collected within the container. After this cleaning process, the object-obscuring portion of the shutter is removed from between the source and the object to allow deposition of the material onto the object. The container confines particles of the matter collected therein during the cleaning process and prevents such particles from falling onto the object during the object deposition process.

Microstrip antenna with circular ring

Abstract: A radar antenna is shown in a first embodiment to have a ground plane and a feed line on opposite sides of a dielectric sheet and a ring-shaped antenna element on another dielectric sheet to form a microstrip assembly wherein such antenna element is capacitively coupled to the feed line. In a second embodiment the radar antenna has a parasitic antenna element on still another dielectric sheet, such parasitic antenna element being in register with the ring-shaped antenna element.

Ventilated gas range with modular cooking units

Abstract: A gas surface range having modular burner cartridges and a down draft ventilation system. The cartridges can be removed for repairing, cleaning, or changing the range top configuration. For example, one cartridge type may include tubular burners and an igniter mounted in a pan so that a grill may be positioned thereover to form a grilling surface. A second cartridge type may include conventional top surface burners and an igniter mounted in a pan. Each range compartment into which the cartridges insert have two orifice hoods and an electrical connector rigidly secured therein. The positioning of an inserted cartridge is such that the mixer heads of the burners align with the respective orifice hoods and a rigid conductor of the igniter makes electrical contact with the connector. The connector also has a second terminal for providing an electrical return for the igniter. One type of cartridge also includes an extending post which permits it to only be inserted in one particular compartment. Furthermore, its presence there is sensed so that activation of either burner automatically causes the down draft system to operate.

Holographic laser protection device

Abstract: A holographic reflector (20) for reflecting laser radiation at a predetermined wavelength. The reflector employs a plurality of holograms (31, 33) which are disposed adjacent to one another and which are conterminous with each other. The holograms (31, 33) are generally disposed in a support structure (21) which may be a visor or goggle arrangement. Each of the holograms may be either parallel fringe holograms or slanted fringe holograms. The angular orientation of the fringes and the relative spacing thereof determine the angular coverage provided by the reflector (20). The reflector (20) provides for reflection of laser radiation at a predetermined wavelength and within a particular angular subtence (DELTA)3,DELTA)4,DELTA)5) while allowing high see-through in the visible wavelength region. Multiple sets of holograms may also be stacked in order to protect against multiple laser sources.

Method and apparatus for baseband generation of a spread spectrum reference signal for use in an LMS adaptive array processor

Abstract: A method and apparatus for baseband generation of a spread spectrum reference signal for an LMS adaptive array processor is provided. An IF summed, weighted spread spectrum signal is output from the processor and translated to baseband to produce an I (in-phase) channel spread baseband signal and a Q channel (quadrature-phase) spread baseband signal. A baseband correlator receives the I channel and Q channel baseband signals and delayed versions of in-phase and quadrature-phase PN signals and produces despread I channel and Q channel baseband output signals. A baseband linear spreader receives the despread I channel and Q channel baseband output signals and the in-phase and quadrature-phase PN signals and produces respread I channel and Q channel baseband signals. A baseband modulator modulates the respread I channel and Q channel baseband signals with a phase-shifted local oscillator to produce the reference signal. The reference signal is subtracted from the spread spectrum signal to produce an error signal consisting essentially of the undesired signal components in the spread spectrum signal. The adaptive array processor minimizes the mean-square value of the error signal to minimize these undesired signal components. If desired, multi-channel capability can be provided by a summer for summing respread I channel and Q channel baseband signals from a plurality of channels in the spread spectrum communication system.

Performance of Diversity Combining Techniques for FH/MFSK in Worst Case Partial Band Noise and Multi-Tone Jamming

Abstract: Diversity combining techniques to be used in frequency hopped MFSK spread spectrum communication systems with explicit redundant transmission are examined. Expressions are given for the conventional linear noncoherent combining technique to compute the BER performance under worst case partial band noise jamming. Results obtained indicate that the conventional linear combining is far from optimum in the jamming environment. In order to combat the worst case jammer, several non-linear algorithms have been examined through computer simulation to obtain the BER performance for comparison. A practical anti-jam combining algorithm is recommended. When binary convolutional code is used in conjunction with M-ary FSK modulation (M ≫ 2), soft decision decoding can be accomplished by means of a M-ary to binary metric conversion algorithm. Modem BER performance based on this algorithm has been obtained for the 8-FSK waveform through computer simulation and is presented in this paper.

Leakage suppression tunnel for conveyorized microwave oven

Abstract: A conveyorized microwave oven having two leakage suppression tunnels in series wherein the first tunnel includes a microwave choke and a second tunnel has a ferromagnetic layer covered with a smooth microwave transparent sheet. The choke tunnel presents a high impedance to microwave energy at the operating or fundamental frequency and the second tunnel attenuates spurious out-of-band radiation which propagates through the first tunnel and is typically concentrated at the harmonics. The ferromagnetic layer absorbs the broad-banded microwave energy and the smooth microwave transparent layer such as Lexan provides a surface that is easily cleanable and acceptable for use in cooking food. The sides of the second tunnel can be pivoted to an opened position by hinges to provide easy access to the inside for cleaning.

Combination microwave and convection oven

Abstract: A combination microwave and convection oven in which a gas burner positioned outside the oven provides heated combustion products which are drawn from the burner area along with vapor from an outlet of the oven by a blower system and the combined output of the blower system is blown into the oven through an oven inlet region in the oven wall. Both the oven outlets and the oven inlet are formed of holes substantially less than one-half wavelength in diameter. A predetermined portion of the blower output system is blown through an exhaust vent thereby creating slight negative pressures in the oven and in the burner plenum to accurately control the air flow through the burner.

Tool and method for cleaving optical fibers

Abstract: An optical fiber cleaving tool comprising a base supporting a sled which is biased to carry an optical fiber clamp thereon away from an inner surface of an orthogonal end wall having extending through it in alignment with the clamp an aperture disposed to receive a fiber optic connector end portion. The connector has a terminal end surface provided with a central aperture through which an optical fiber end portion extends to the clamp on the sled for axial tensioning. Aligned with the aperture in the wall is a recess having an end surface chordally disposed with respect to the aperture for abutting engagement with the terminal end surface of the connector and serving as a reference plane. A cutter rotatably mounted above the recess end surface has a peripheral portion from which protrudes resiliently a diamond-tipped end portion of a wafer-like blade which is slidably disposed in a slot extending diametrically of the disc and having a thickness greater than the thickness of the blade. A leaf spring overlying the slot has a flexible end portion bearing against an underlying ball which presses resiliently on the wafer-like blade in the slot to urge it laterally into resilient contacting relationship with the terminal end surface of the connector for nicking the optical fiber at a transverse plane disposed in predetermined positional relationship with the terminal end surface of the connector.

Method of controlling antiaircraft fire

Abstract: A method of controlling antiaircraft fire is described in which an aircraft is tracked continuously during the flight of a burst of projectiles and the probability of a hit is continuously revised according to the latest target maneuver as the projectiles proceed to the intercept point. If, before all of the projectiles reach the aircraft, the probability of a hit falls below a specified level, another burst of projectiles is fired. As this second burst proceeds to target its computed probability of hit is combined with that of the previously fired burst to determine the cumulative probability of hit of the two bursts taken together. If, before the second burst reaches the target, the cumulative probability falls below the specified level then a third burst is fired. This activity repeats until the cumulative probability of hit is driven up and kept up above the specified level.

Radio frequency signal direction finding apparatus

Abstract: A system for determining the difference in phase between a pair of radio frequency signals wherein quadrature components of one of such pair of signals are alternatively combined with the other one of such pair of radio frequency signals to provide sum and difference signals thereof. Alternative ones of such sum and different signals are alternatively coupled to an output to provide a composite signal having a phase related to the difference in phase between the pair of radio frequency signals. The composite signal is then amplified and the phase of the amplified radio frequency signal is detected to determine the difference in phase between the pair of radio frequency signals.

A model for numerical simulation of nonstationary sonar reverberation using linear spectral prediction

Abstract: An innovative approach to the numerical generation of nonstationery reverberation time series is presented and demonstrated. The computer simulated reverberation time series are of high quality, in that they are accurate representations of those which would result from an actual sonar system (transmit/receive and horizontal/ vertical beampatterns; pulse type, shape, length, and power; frequency and sampling rate), platform (speed and depth), and environment (wind speed and direction, backscattering strengths, and propagation loss). Volume, surface, and/or bottom reverberation as seen by a multiple beam sonar on a moving platform is generated. The approach utilizes recent developments in linear spectral prediction research in which the spectra of stochastic processes are modeled as rational functions and algorithms are used to efficiently compute optimal estimates of coefficients which specify the spectra. A two-fold sequence is formulated; first, the expected reverberation spectra for all beams are predicted and, second, the stochastic time series are generated from the expected spectra. The expected spectra are predicted using a numerical implementation, referred to as the REVSPEC (reverberation spectrum) model, of a general formulation of Faure, Ol'shevskii, and Middleton. Given the spectra, the Levinson-Durbin method is used to solve the Yule-Walker equations of the autoregressive formulation of linear spectral prediction. The numerical implementation of the approach, referred to as the REVSIM (reverberation simulation) model, produces nonstationary coherent multiple-beam reverberation time series. The formulation of the REVSIM model is presented and typical results given. A comparison is made between the simulation outputs of the REVSIM model and those of the REVGEN (reverberation generator) model, a standard well-accepted time series simulation model, to demonstrate the validity of the new approach.

Radio frequency network having plural electrically interconnected field effect transistor cells

Abstract: A radio frequency network is provided having a plurality of field effect transistor cells, each one of such cells having a reactive element, and coupling means for electrically interconnecting the plurality of field effect transistor cells, such coupling means having an impedance in accordance with the reactance of the reactive elements of the cells to provide such radio frequency network with a predetermined characteristic impedance related to the impedance of an input circuit which feeds radio frequency energy to an input one of the plurality of cells. With such arrangement the coupling means and the plurality of field effect transistor cells provide the radio frequency network with a predetermined characteristic impedance which is related to the impedance of the input circuit.

Printed circuit board holder

Abstract: A circuit board holder and module including the circuit board and holder are described wherein a cover plate integral with the holder is in thermal contact with the heat producing elements mounted on the circuit board. The heat generated in the elements is transferred through the cover plate to the peripheral portions of the holder where the holder is in contact with a heat sink.

Parallel plate lens antenna

Abstract: An antenna system is provided for producing a plurality of differently directed beams of electromagnetic energy, each one of such beams being associated with a corresponding one of a plurality of beam ports, each one of such beams being produced from a common array of antenna elements. The antenna system includes a radar frequency energy lens assembly having a plurality of array ports coupled to the plurality of antenna elements. The lens assembly includes a radio frequency lens having a plurality of lens ports disposed about peripheral portions thereof. Each one of a first portion of such plurality of lens ports is coupled to a corresponding one of the antenna elements through a corresponding one of the array ports and each one of a second, opposing portion of the plurality of lens ports being coupled to a corresponding one of the beam ports. Each one of the lens ports in one of the portions thereof includes a pair of tapered feeds. A power divider/combiner is provided for each one of the pair of tapered feeds, such power divider/combiner having a pair of branch lines coupled to the pair of tapered feeds and a common line coupled to the one of the beam ports or array ports coupled to such lens port. The electrical lengths between an input to the common line and the outputs of the pair of tapered feeds coupled to the branch lines of such power divider/combiner are equal.

Dispersion equalized ring laser gyroscope

Abstract: A ring laser gyroscope system uses a non-planar path and no-depolarizing Faraday bias means to achieve four-frequency differential operation. The use of the non-planar path eliminates the crystal rotator normally used to provide reciprocal bias and therefore eliminates scattering surfaces and a major cause of thermal sensitivity. The non-depolarizing Faraday means, such as a thin glass slab having a component of magnetic field along the optic axis of the laser, is used to reduce the corresponding thermal sensitivity of the traditional Faraday bias element normally implemented by a crystal such as quartz. Eliminating these major sources of drift then allows higher-order sources of drift to be corrected. Zeeman splitting of the laser gain medium is used to provide an equal amount of dispersion to each of the two counter-travelling waves of each wave pair, thus eliminating small amounts of drift due to the different phase shifts produced in the propagating waves by the gain medium.

Vapor phase epitaxial growth of carbon doped layers of Group III-V materials

Abstract: An epitaxially grown high resistivity crystalline layer of gallium arsenide is produced in a reactor vessel with a predetermined amount of carbon dioxide introduced during growth of the high resistivity gallium arsenide (GaAs) crystalline layer to provide carbon as a dopant. Thus, a plurality of carbon atoms is provided in the crystal, such carbon atoms having electrons at energy levels between a valance energy band and a conduction energy band of the GaAs crystal. With these energy levels, the carbon atoms are substantially ionized at room temperature by accepting a plurality of electrons from the valance band of the GaAs. The presence of these carbon ions in the crystal compensates for a stoichiometric defect which occurs during epitaxial growth of the GaAs crystalline layer. This results in a high resistivity layer which provides a buffer layer between a GaAs substrate and an active GaAs layer. Further, by introducing carbon in the form of carbon dioxide, oxygen released during reduction of the carbon dioxide by reacting the carbon dioxide with hydrogen during the doping of the GaAs produces water. The water reduces the concentration of unwanted silicon oxide material generally introduced by the reactor vessel and contaminants and which is associated with unwanted background donor doping of the GaAs. By reducing the concentration of silicon oxide, the concentration of stoichiometric defects becomes the principle donor source, thus enabling optimum compensation thereof with carbon doping.

Method for audio editing

Abstract: A method for determining an acceptacle splice point is provided to facilitate splicing of a first segment of an audio signal to a second segment thereof. According to the method, an audio signal is converted into a sequence of samples and first and second edit points are selected along the sequence. The first edit point represents a nominal ending point of the first audio segment, and the second edit point represents a nominal starting point of the second audio segment. According to the method, a plurality of samples in a correlation window following the first edit point are weighted and correlated with a plurality of weighted samples in a correlation window following the second edit point for each position of the second edit point. The position of the second edit point is then shifted to the next sample in the sequence. After the correlation is calculated for each position of the second edit point, the location of an acceptable splice point can be determined. Specifically, if an average magnitude difference function (AMDF) is utilized for the correlation, the position of an acceptable splice point is that position of the second edit point which produces a minimum AMDF. However, if a cross correlation function (CCF) is utilized for the correlation, the position of an acceptable splice point is that position of the second edit point which produces a maximum CCF.

Detector with variance sensitivity

Abstract: In a radar or sonar system wherein the detection of a target is to be accomplished with a constant false alarm rate (CFAR), a circuit is provided for adjusting the input to a comparator which compares the received echo signals against the value of a threshold in order to detect targets of interest. The mean value of the background noise is subtracted from the signal, and the resulting difference is divided by the square root of the variance of background noise. The use of the variance compensates for sweep-to-sweep correlation and non-stationarity (in the statistical sense) as is found in clutter so that the clutter, upon the customary sweep-to-sweep integration of the signal, does not tend to introduce a false echo.

Regulated microwave oven and method, using uniformly spaced, integral cycle control

Abstract: A method and apparatus for regulating a microwave oven to a predetermined output power level. The anode current or a voltage corresponding to it is monitored to provide a signal indicative of the actual output power of the magnetron. Time is divided into a sequence of equal time intervals, each interval corresponding to fixed number of ac line cycles. In accordance with the signal, the number of ac cycles to be supplied to the power supply for each interval to regulate the output power towards the regulated level is determined. The determined number of cycles are supplied by switching at the zero current crossings between the line and the power supply. The switching is executed so that the supplied ac cycles are distributed substantially uniformly over the particular time interval.

Laser gyro output optics structure

Abstract: A four frequency laser gyroscope system having a rugged and compact output structure for producing output signals representing the frequency differences between counter-circulating wave pairs circulating as two beams within the gyroscope cavity. A partially transmitting dielectric mirror forms both one of the cavity reflectors and the means for extracting a small portion of each beam. The two extracted beams are combined on a beam splitter. Both the transmitted and reflected beams from the output of the beam splitter, each containing waves of all four frequencies, are utilized. Each resultant beam is then polarization discriminated to extract the desired signal content. The entire structure is adapted for rigid mechanical coupling and may be constructed to have a small size.

Digitally controlled power supply

Abstract: A high power factor AC to DC power supply having a high frequency pulse producing circuit comprising an inductor supplied with rectified raw AC power through a semiconductor switch which provides dynamic power factor correction by maintaining the width of the on-times of the switch substantially constant throughout each cycle of the input AC power. The peak energy stored in the inductor during the on-times are a function of the amplitude of the instantaneous voltage of said rectified AC power, so that each time the switch is turned off, the output pulse of current supplied to the load by the inductor has a time duration which is a direct function of the instantaneous voltage value of the rectified AC power. The output load has a filter whose time constant is greater than a cycle of said rectified AC power, and the average on-time of said switch is varied over a number of cycles of said AC power to regulate the output voltage of said supply.