Showing papers by "Raytheon published in 1970"

Laser-Doppler system for detection of aircraft trailing vortices

Abstract: This paper reviews the results of a test program utilizing a CW CO 2 laser-Doppler velocimeter system that has demonstrated the capability of detecting wing tip vortices by the measurement of Doppler shifted back scatter from atmospheric aerosols naturally suspended in the atmosphere. The velocity signatures of vortices generated by a C-47 aircraft making low altitude cooperative flybys are shown. Some considerations of an operational detection system are given.

Vehicle command and control system

Abstract: A dual frequency ranging and communication system for communicating with and locating mobile vehicles in a multipath environment such as an urban center. This system functions in urban areas for both communication and ranging where line of sight radiation techniques may not properly function. A plurality of remote relay stations are located at points throughout the urban area, each station receiving and transmitting coded digital data and tone signals, the tone signals being used for phase ranging. Each of the vehicles is equipped with a transponder responsive only to the radio signal having a formatted message including the vehicle identification code with a ranging tone suitably impressed thereon. The formatted signal is transmitted from one of the relay stations at a first frequency and picked up by a preselected number of other relay stations as well as by the vehicle transponder. The vehicle transponder in turn generates a reply signal at a second frequency containing message data and a tone signal modulated on the second frequency for use in ranging, all of which signals are processed at a central location.

Atmosphere Propagation and Communication Channel Model for Laser Wavelengths

Abstract: The advent of the laser has generated much interest in its use for communication. Consideration is given in this paper to obtaining a communication channel model of the atmosphere for laser frequencies. For this purpose a fairly exhaustive, tutorial, and partly critical review of a major part of the extensive literature pertaining to theoretical and experimental results on the propagation of laser signals in the atmosphere is given. Some of the basic characteristics of the channel for Which detailed results are given are 1) channel time spread (or, equivalently, channel coherence bandwidth) due to multipathing and dispersion, 2) channel gain, 3) channel doppler spread and coherence time, 4) channel spatial coherence and amplitude covariance functions. Consideration is given to both point receivers and area receivers, heterodyne and direct detection receivers, nonplanar (i.e., spherical and beam) wave propagation, and infinite plane-wave propagation. The results are given for clear weather conditions. Brief attention is given to additive noise. In reviewing the extensive literature dealing with the propagation of optical signals through a turbulent medium, an attempt is made to put this varied, diverse, and in some instances controversial material into proper perspective; to note where theoretical results derived for one set of conditions were applied to experimental results obtained for another set of conditions; to correct some invalid conclusions drawn from some theoretical results as far as signal degradation effects and parameter variations; and to indicate where out-of-date vertical profile models were used with updated models being given, and where possible the new theoretical predictions based on these models provided. The paper should, as a result, be of help to those familiar with the literature as Well as those who are not. For those not acquainted with the literature, in addition to providing a fairly in-depth knowledge of the characteristics of propagation through a turbulent medium and an indication of the status of our understanding of this subject, the paper should provide a stepping stone for obtaining a more thorough understanding of the subject and for doing work in the field.

Surface acoustic wave delay lines with small temperature coefficient

Abstract: Surface acoustic wave delay lines having a vanishing first-order temperature coefficient of delay time near room temperature have been constructed. The devices were operated near 60 MHz and had about 5 µs delay. The surface waves, generated and received using interdigital electrodes, were propagated along the twofold crystallographic axis of ST-cut quartz. The phase delay change as a function of temperature has a parabolic temperature dependence with a second-order coefficient of approximately 31.5 × 10-9/° C2.

Demand access digital-communications system

Abstract: This disclosure relates to a multiparty data-transmission system in which a central location controls the communication traffic in a transmission loop while at the same time permitting remote locations to independently request transmission privileges or ''''demand access'''' to the communications loop without interference or message overlap either with demand access requests originating at other remote locations or with other data which may be present on the transmission line, whether destined to or from the central location.

Harmonic generation in octave bandwidth traveling-wave tubes

Abstract: This paper describes the investigation of harmonic generation in traveling-wave tubes (TWT's) via large-signal analysis and digital computer techniques. Efficiency degradation and harmonic power content are shown to be importantly related to such TWT design considerations as circuit dispersion, harmonic coupling impedance ratio, and gain level. Also described is the phenomenon of second harmonic interference in the beam bunching process and how it leads to substantial efficiency reduction in TWT's employing relatively nondispersive structures.

Image detection through bipolar correlation

Abstract: The purpose of this paper is to describe the bipolar reference concept. A bipolar reference is simply a reference that can take on a continuous range of both positive and negative numerical values. It will be shown that for map matching via the convolution operation, references that yield maximum signal-to-noise ratios, in general, will be bipolar references. Algorithms for generating bipolar references and digital simulation results are given.

Crossed field microwave device

Abstract: A traveling wave crossed field device is disclosed having dual sets of spaced conductive cathode electrode segments in parallel electrically with one set cooperating as a control element and the remaining set performing primarily as the emitter Discrete electron cycloidal trajectories are considered in arriving at the spacing between adjacent elements The cathode configuration provides for space charge control throughout the entire interaction region Additionally, high- mu switching, as well as high-speed shutoff characteristics, has been achieved by means of very low-control voltage requirements

Critique of Current Theories of Akhieser Damping in Solids

Abstract: There are two widely used theories of ultrasonic attenuation in the Akhieser ($\ensuremath{\Omega}\ensuremath{\tau}\ensuremath{\ll}1$) regime. Woodruff and Ehrenreich used the Boltzmann equation and found that the attenuation was a function of the specific heat of the thermal phonons. Mason and Bateman obtained the fundamentally different result that the attenuation also involved the thermal energy. It is shown here that the Mason-Bateman theory contains both mathematical and conceptual errors and that its apparent agreement with experimental data on Si and Ge is fortuitous.

Microstructure Development in Yttrium Iron Garnet

Abstract: Sintering and grain-growth rates were determined for yttrium iron garnet as a function of the yttrium/iron ratio. Rates decreased with an increase in this ratio; this behavior is interpreted as a result of the oxygen content variation through the garnet field. For constant sintering time, density and grain size, as well as microstructure-dependent properties, varied through the garnet field. Remanent magnetization and coercive force in particular depended on composition and sintering temperature. The rf field for nonlinear spin-wave excitation, hcrit, measured for dense samples with grain sizes from ∼4 to 30 μm, varied by a factor of four.

Optical scanning system

Abstract: An optical scanning system wherein infrared energy radiating from an object is directed to a Porro prism, such Porro prism being rotatable about the boresight axis of the optical scanning system so that the image of the object rotates, in the image plane of such system about its boresight axis, at an angular rate twice that of the Porro prism. A linear array of infrared detector elements is disposed in the image plane radially from the boresight axis of the scanning system. The angular deviation of the object from the boresight axis of the scanning system is measured by determining: (1) the angular position of the Porro prism when one, or more, of the infrared detector elements in the linear array is energized; and (2) which one, or ones, of such elements is energized.

Imaging system utilizing spatial coding

Abstract: An imaging system suitable for use with high energy nuclear particles or photons such as gamma radiation and X-radiation. The system provides means for illuminating an object with radiation as well as spatially coding the illuminating radiation or emitted radiation if the object is self-luminous, to provide a composite image representing the summation of the shadows from all points of the source of illumination. Spatial modulation is accomplished by a mask having a coded pattern of transparent and opaque regions linearly scanned in time. The resulting signal has the characteristics of a chirp waveform typical of pulse compression radars. The composite image is readily decoded by a delay line having a phase or delay characteristic complementary to that of the spatial modulation pattern.

Visual display system

Abstract: A cathode ray display system in which characters are generated by a monoscope and in which the character address information for the entire raster of a cathode ray tube display is stored in a dynamic memory which is continuously read and regenerated by character entry and read-out logic which controls the monoscope scanning to supply the proper characters to the cathode ray tube as it scans in a raster.

Mutual coupling analysis of a conformal array of elements on a cylindrical surface

Abstract: The analysis of multiport antennas may be approached by resorting to the powerful concept of eigenexcitations of the structure. They may be defined as the eigenvectors of the admittance matrix, i.e., those sets of voltages and currents at the antenna terminals which are related simply by a proportionality factor (eigenvalue of the admittance matrix). Similarly, the eigenexcitations may be alternatively defined as the eigenvectors of the scattering matrix. The analysis for this special kind of excitation is sometimes relatively easy. The general case may then be treated by utilizing superposition principle. An array of infinitely long longitudinal slots equispaced on a conducting cylinder is analyzed in detail. The eigenvectors of the admittance and scattering matrices are easily found because of the symmetry of the structure. Expressions for the eigenvalues of these matrices, and for the radiation patterns due to the array eigenexcitations, are found in the form of infinite series rapidly convergent (even for cylinders of large radius). By using linearity an expression for the radiation pattern of the single excited element in the array environment (the main result of this paper) is then established. Expressions are also given for the coupling (or scattering) coefficients. A number of numerical examples with different cylinder radii are discussed in detail.

Pulse compression radar system

Abstract: A pulse compression radar system wherein a coding signal indicative of the modulation to be impressed on a transmitted signal is read out of a read only memory and converted to: (a) an analog modulation signal impressed on a radio frequency carrier; and (b) the complex conjugate of the discrete Fourier transform of the coding signal stored in a memory. Each echo signal resulting from illumination of a different target by the modulated transmitted signal is converted to a corresponding digital form indicative of the modulation on each such echo signal, transformed in a discrete Fourier transform and correlated with the stored complex conjugate of the coding signal for the transmitted signal. The resulting correlation signal is weighted and then converted back to a time varying signal in an inverse discrete Fourier transform for utilization.

Combined infrared-radar detection system

Abstract: A combined infrared-radar detection system wherein a radar antenna also serves as the primary mirror in an infrared focusing arrangement.

Heat transfer structure

Abstract: A heat transfer structure and system including a matrix of tubes and spheres bonded together to provide a conduit for a first fluid such as water and a plurality of interconnected paths for a second fluid such as hot flue gas. The paths are made up of the spaces between the spheres such that the walls of the paths are portions of spherical surfaces. The total path length is made less than twenty times the average radius of curvature of the spherical surfaces and the spacing between adjacent tube elements is of the same order of magnitude as the average length of the paths. A water heater or boiler so constructed may be made to transfer substantially all the heat in a flue gas to water in an average path length of one inch or less.

Acoustic impedance matching system

Abstract: A transducer assembly incorporating a stratified medium for conducting acoustic waves from an acoustic source of relatively high impedance, such as a piezoelectric crystal, to a gaseous environment of relatively low impedance, the stratified medium including typically at least one layer of a foam structured low density plastic material, whereby uniform variations in impedance are provided progressively from the source through the layers of the stratified medium into the gaseous environment to effect an impedance match.

The Receiving Antenna and Micrewave Power Rectification

Abstract: In a space power system the energy captured from the sun by means of a gigantic solar cell array is relayed to the Earth by means of a microwave beam where the microwave energy is captured and conv...

Visual display system

Abstract: A limited access real-time data communication and display system wherein access to selected portions of stored data may be gained by the insertion of a coded identification card into the system resulting in the display on a cathode-ray tube of the selected data in a line raster adjacent to which and aligned with are a plurality of line selection switches which allow an operator to gain access to additional data in accordance with the displayed information and in accordance with the coded identification card.

Shielded optical radiation detecting device

Abstract: An optical radiation detecting device adapted particularly for temperature detection systems such as welding apparatus and which comprises a fluid-cooled fiber optic radiation sensing and transmitting means having means for shielding the sensing portion of the device from extraneous or stray radiation in the visible and near visible portions of the spectrum.

Disturbance sensitive switch

Abstract: A disturbance sensitive device comprising an electrical switch having resilient means for supporting a movable contact member in normally open relationship with a stationary contact member, and structured to provide prolonged closure when the device is disturbed. A further improvement includes a second resilient means which is carried on the movable contact member for reducing the gap between the contacting members and increasing the closure time interval.

Energy absorber and evaporative cooling system

Abstract: A transmission line termination load or attenuator device is provided with energy absorbing means including a medium for absorption of thermal energy, particularly, in the electromagnetic spectrum. The device is coupled to an evaporative type cooling system to evolve a relatively low pressure, low flow rate means for handling extremely high power levels with a relatively small volume of absorbent. The device utilized in either application has substantially low reflection coefficient characteristics over relatively wide frequency bandwidths and may be in either rectangular or coaxial waveguide configurations.

Optical depth finder and elements therefor

Abstract: AN IMPROVED OPTICAL DEPTH FINDER, AND ELEMENTS THEREFOR, FOR DEPTH SOUNDING AND DETECTION OF SUBMERGED TARGETS FROM AN AIRBORNE VEHICLE. THE DISCLOSED SYSTEM USES A COHERENT BEAM OF POLARIZED LIGHT FROM A LASER DIRECTED DOWNWARDLY TOWARD THE SURFACE OF A BODY OF WATER AND PROCESSES THE POLARIZED SURFACE SPECULAR REFLECTED ENERGY, ENERGY REFLECTED BY SUBMERGED TARGETS WITHIN THE BEAM, AND ENERGY REFLECTED BY THE BOTTOM OF THE BODY OF WATER TO DERIVE THE DESIRED INFORMATION. MEANS ARE PROVIDED SELECTIVELY TO ATTENUATE THE REFLECTED ENERGY IN ACCORDANCE WITH THE PARTICULAR SOURCE THEREOF SO AS TO PERMIT THE DYNAMIC RANGE OF THE PROCESSOR OF THE REFLECTED ENERGY TO BE REDUCED AND THE SYSTEM TO BE USED WHEN THE HEIGHT OF THE AIRBORNE VEHICLE CHANGES OR CONDITION OF THE WATER VARIES.

Highway vehicle sensor system

Abstract: A highway vehicle sensor, consisting of a main loop energized with low radiofrequency energy and having side legs spaced apart a predetermined distance, is buried in the surface of a highway. Around each side leg is a probe loop in which a signal is generated by the presence of a vehicle over the probe loop. The two output signals from the two probe loops are processed to determine vehicle presence, direction of travel, speed and length and headway between vehicles on the highway.

Probing linear filters-- Signal design for the detection problem

Abstract: The problem of designing an optimum probing signal for discriminating between two known linear filters in the presence of noise is considered. It is shown that in the general case of colored noise, the optimum signal is the solution of two simultaneous integral equations. An expression for the probability of error is given, and some illustrative examples are presented.

Remote underwater device activating system

Abstract: An apparatus for activating a remote underwater device comprising detecting means responsive to incident acoustic waves provides signal indication of the presence or absence of predetermined frequencies thereof. A logic arrangement decodes only those signal indications indicating a joint presence of some of the pre-selected frequencies and the absence of others of the pre-selected frequencies. This discriminates signals against broad-band acoustic noise. The logic arrangement further includes means for activating the remote underwater device only if the decoded successive signal indications match a predetermined pattern. This further discriminates between a present received acoustic wave and a prior transmitted acoustic wave present because of multipath or reverberation. Lastly, a timing and gating means responsive to a first decoded signal indication couples the detecting means to the logic arrangement only at periodic intervals thereafter. The time gating also reduces the chances of obtaining a prior multipath and reverberation signal because the pulse repetition period of the successive acoustic waves is predetermined.

Balanced optical demodulator

Abstract: A demodulator for optical signals, the contemplated demodulator including a polarizer and mirror arrangement for combining the signals to be demodulated and optical local oscillator signals into a first and a second composite beam, the first beam being modulated in a manner corresponding to the algebraic sum of the signals to be detected and the optical local oscillator signals and the second beam being modulated in a manner corresponding to the algebraic difference between such signals. Each composite beam is directed to a different photodetector and the difference signal between the electrical output signals of the photodetectors is derived. Such difference signal, which is proportional only to the product of the signals to be demodulated and a constant related to the optical local oscillator signals, may then be processed to derive the desired demodulated signals.