Showing papers by "Raytheon published in 1971"

Divergence of the Kalman filter

Abstract: The Kalman estimation technique is examined from the point of view of the asymptotic behavior of the errors in the estimates. It is shown that, under certain conditions, the mean-square errors may become unbounded with time, and that this divergence may or may not be correctable by increasing the intensity of process noise assumed in the filtering model General results are derived for multidimensional systems, and both "true" and "apparent" divergence are demonstrated by a simple scalar system. Divergence due to numerical inaccuracies is considered, and an example problem in orbital navigation is used to demonstrate divergence and its elimination.

Acoustic surface wave filters

Abstract: Acoustic surface waves offer several advantages in the construction of delay lines and filters in the UHF range. In these devices the frequency response is determined by the finger spacing and overlap of the interdigital comb structures used as input and output transducers. Models are developed to describe these devices, and the predictions of these theories are compared with several experimental filters, including band-pass filters and dispersive delay lines.

Signal-to-Noise Relationships for Coaxial Systems that Heterodyne Backscatter from the Atmosphere.

Abstract: This paper analyzes the signal-to-noise ratio for a coaxial laser system that heterodynes the signal backscattered from the atmospheric aerosol. The laser radiation, which is assumed to have a wavefront with a gaussian amplitude distribution, is transmitted into the atmosphere through a telescope. Radiation is collected by the same telescope and directed onto a detector where it is mixed with a local oscillator beam originating from the same laser source. The signal-to-noise ratio at the output of the detector is calculated under shot noise limited conditions. The calculation is general and applies for both near and far fields and for focused and unfocused systems. Three specific cases are considered. These are a pulsed system, a cw system illuminating an infinite target, and a cw system illuminating a target of finite extent.

Phased array system

Abstract: A phased array antenna utilizing a parasitic reflector in which the area of the array of radiating elements is smaller than the area of the reflector. The reflector has a concave surface which, in one embodiment of the invention, is a hyperbola of revolution for collimating the rays of radiation incident thereupon from the array of radiating elements. The surface of the reflector is particularly adapted to permit the generation of a set of phase shift command signals by means of a novel ray tracing program to provide a collimated beam which may be scanned in response to the phase shift imparted through radiation radiated by the radiating elements. A narrow beam of radiation is obtained by virtue of the relatively large sized reflector even though the dimensions of the array of radiating elements are relatively small.

A new low-loss high-k temperature-compensated dielectric for microwave applications

Abstract: A new dielectric material has been developed with a temperature-stable dielectric constant of 38. The low loss exhibited at microwave frequencies, the excellent reproducibility, and the good mechanical properties of this dielectric make it an attractive substrate for microstrip circuits. The dielectric is also suitable for the resonant elements of dielectric filters and stabilizing cavities for hybrid solid-state sources.

Speed measurement system

Abstract: A speed measurement system utilizing a plurality of radiators coupled to a medium for transmitting radiant energy signals within the medium between the radiators in a manner wherein the frequency of the radiant energy is adjusted to retain a predetermined number of wavelengths between a transmitting radiator and a receiving radiator independently of the speed of the medium relative to the radiators. In one embodiment of the invention sonic signals are transmitted through a fluid medium which is moving relative to the radiators. A phase locked loop is interconnected between a pair of radiators by means of a switching arrangement which permits alternative transmissions of sonic energy in the direction of fluid movement (downstream) and in the direction opposite to the fluid movement (upstream). Phase lock is obtained when the frequency of the phase locked loop is such that the predetermined number of wavelengths of the sonic transmission is present. The speed of the fluid medium as well as the speed of sound propagation within the fluid medium are obtained by arithmetic combinations of the values of the upstream and downstream frequencies.

Subsurface traveling wave antenna

Abstract: A subsurface traveling wave antenna for generating and receiving primarily surface waves in either the vertical or horizontal position below the surface. The antenna comprises an insulated linear radiating element terminated with a matched load for coupling a portion of the surface wave component. Impedance elements interconnecting portions of the radiating element at periodic intervals along its extent provide speed matching between the phase velocity of the wave propagating down the radiating element and the surface wave component.

Energy seal for high frequency energy apparatus

Abstract: A high frequency oven having a door sealed to the oven by a seal which prevents the escape of high frequency energy between the door and the oven by acting as a choke to energy modes attempting to pass across the seal in which excitation of energy in a band of frequencies including the desired operating frequency range of the oven is controlled along the seal. An energy absorbing gasket surrounds the seal to absorb any energy passing outwardly from the energy seal.

Remotely powered transponder

Abstract: A transponder having a circuit for the extraction of power from an incident interrogating beam of electromagnetic energy, the extracted power being utilized to operate a digital coding circuit. The transponder further comprises an oscillator circuit for developing a train of pulses of electromagnetic energy with successive pulses occurring in a coded format in accordance with a digital code imparted by the digital coding circuit. The transponder is of sufficiently small size to be affixed in the form of a tag to automobiles, personnel, containers and other objects to be identified. The electronic tag communicates with an interrogation system.

Nonparametric Radar Extraction Using a Generalized Sign Test

Abstract: A nonparametric procedure used in a constant false alarm rate (CFAR) radar extractor for detecting targets in a background of noise with unknown statistical properties is described. The detector is based on a generalization of the well-known two-sample sign test and thus requires a set of reference noise observations in addition to the set of observations being tested for signal presence. The detection performance against Gaussian noise is determined for a finite number of observations and asymptotically, for both nonfluctuating and pulse-to-pulse Rayleigh fluctuating target statistics. It is noted that the performance loss, as compared to the optimum parametric detector, depends critically on the number of reference noise observations available when the number of hits per target is not large. In the same case a much larger loss is also found for a pulse-to-pulse fluctuating target even though the asymptotic loss is the same as for a nonfluctuating target. A comparison is finally made with a detector based on the Mann-Whitney test, which usually is considered to be one of the better nonparametric procedures for the two-sample case.

Interchassis cable carrier

Abstract: An electrical console comprising a cabinet having a pair of spaced parallel assemblies slidably supported therein to move in and out of the cabinet independently of one another, a cable carrier disposed between the assemblies and including a pair of hinged arms each of which has a respective end portion pivotally attached to a respective one of the assemblies, and an electrical cable having opposing ends each of which is attached to a respective one of the assemblies and having an intermediate length secured to the arms of the cable carrier.

Multi-beam array antenna

Abstract: A multi-beam array antenna assembly is disclosed, such assembly being adapted to form a plurality of simultaneously existing beams of radio frequency energy, each one of such beams having the gain of the entire antenna aperture and a different scan angle. The preferred embodiment of the contemplated assembly is fabricated, using printed circuit techniques and matching sections on a dielectric substrate, to form an array of antenna elements and constrained electrical paths for radio frequency energy between each one of the antenna elements and a number of feed ports. The electrical length of each one of such paths is adjusted so as to focus radio frequency energy in each one of the desired beams at a different feed port. The preferred embodiment also illustrates a multi-beam array antenna assembly having antenna elements spaced to increase the scan angle of each desired beam.

Temperature compensated acoustic surface wave device

Abstract: A temperature compensated acoustic surface wave device, such as a surface wave delay line is provided in which temperature compensation is provided by the deposition of an interdigital electrode structure on a substrate with an overlay film surface of piezoelectric material of a predetermined thickness. A double substrate arrangement is also disclosed in which the interdigital electrode structure is deposited upon the surface of a non-piezoelectric layer which in turn is placed upon the surface of a piezoelectric substrate.

Transformer system for orthogonal digital waveforms

Abstract: A transformation system for transforming a set of input data samples into a set of output transform components, the transformation being based on the use of a set of orthogonal digitally generated waveforms analogous to the use of sinusoids in a Fourier spectral analysis. The transformation is accomplished by sequentially storing, summing, and subtracting selected data samples and combinations thereof to effect a matrix multiplication of the set of input data samples.

Floating point number processor for a digital computer

Abstract: A processor for digital numbers, specifically a multiplier using a ''''floating point'''' technique, is disclosed. The disclosed processor is adapted to determine the product of two unnormalized digital numbers, each one of such numbers being expressed as a mantissa and a signed exponent of a selected base, and to express such product as a mantissa with the greatest possible degree of significance and a signed exponent of the base. The processor is operative simultaneously to determine the sum of the exponents and the partial products of the mantissas of the numbers being processed and to normalize one of such mantissas, adjusting the sum of the exponents correspondingly. Means are also provided to stop the multiplication process as soon as all significant partial products are determined.

Behavior of ferrites in the microwave frequency range

Abstract: Present and foreseen applications of ferrites in the microwave frequency range are reviewed. The material parameters that are required or desirable for these applications are discussed. Special attention is given to the losses observed in polycrystals at biasing fields much smaller or much larger than the field for resonance. The loss may be characterized by an effective linewidth ƊHeff, which is a function of frequency and dc magnetic fieldstrength. In low loss polycrystals ƊHeff is typically much smaller in the off-resonance regions than near resonance, but even in the best polycrystals it is considerably larger than in good single crystals. The near-resonance behavior of ƊHeff can be explained quite well in terms of inhomogeneity induced scattering of energy into spin waves, having wavenumbers comparable to the inverse grain size. The off-resonance behavior is less well understood. Inhomogeneity induced scattering into phonons is discussed as a possible loss mechanism. For fine-grain ferrites the observed dependence of ƊHeff upon grain size and that of the spinwave linewidth (inferred from the instability threshold) upon grain size and frequency is in rough agreement with .the behavior expected theoretically for this mechanism. The microwave properties of partially magnetized ferrites are discussed. A simple theoretical formula, applicable in the demagnetized state, is derived. It is shown to agree reasonably well with the observed behavior both at high frequencies (where the losses are low) and at intermediate frequencies (0.1-3 GHz) (where the losses are high).

Noise measure of metal-semiconductor--metal Schottky-barrier microwave diodes

Abstract: We calculate the impedance and noise measure of metal--semiconductor--metal (m.s.m.) microwave diodes. Assuming that the noise is caused by space-charge-smoothed shot noise accompanying the d.c. bias current, one comes to the conclusion that noise measures less than unity are possible. If shot noise is the main contributing noise source, then m.s.m. diodes should become extremely low-noise microwave oscillators and amplifiers.

Random access memory

Abstract: A random access memory, suitable for monolithic integrated circuit fabrication, having the ability to simultaneously write therein binary data applied thereto and read therefrom binary data previously written therein Each bit of such binary data stored by the random access memory is stored in a binary storage cell, each such cell having independent read and write addressing circuitry Binary data is written into selected ones of a plurality of binary storage cells by establishing in such selected cells a relative voltage polarity Binary data is read from selected binary storage cells by sensing the relative polarity of the voltage established therein

Real time fourier transformation apparatus

Abstract: An apparatus for performing real-time Fourier transformation of a time varying signal by taking successive digital samples in a shift register means and repeatedly transforming preselected pairs of said samples as the samples are progressively shifted down the register. The successive samples are ordered in the register in a binary sequence from 0 to 2n-1 while the pairs are selected when the binary distance between them is equal to 2n m, m being the transformation number, each pair Xa,m, Xb,m being related to its transformed magnitude Xa,m 1 and Xb,m 1 by the relations

Method of intermetallic bonding

Abstract: An intermetallic compound of a metal such as mercury, gallium or indium plus one of the more nobel metals such as copper, gold, nickel, silver or palladium which is utilized for bonding together two metals without the use of any flux or binder so that an excellent thermally and electrically conductive bond is formed. Methods of producing the bonding agent and fabricating structures therewith are disclosed.

System for activating a remote underwater device

Abstract: A system for activating a remote underwater device using a frequency coded acoustic wave generator having at least one notch frequency in the transmission spectrum. The generator is adapted to transmit simultaneous assertion and negation frequencies. An acoustic responsive receiver is located at the remote underwater device. The receiver includes a code validation logic arrangement responsive to each received acoustic wave for verifying the simultaneous presence and absence of the assertion and negation frequencies. A utilization circuit, also in the receiver, is responsive only to a verification signal from the validation logic.

Nd: YAG laser-irradiation-induced damage to LiNbO 3 and KDP

Abstract: It is shown that internal damage in LiNbO 3 and KDP occurs at the same or lower levels of irradiation than surface damage. This is found in crystals used as frequency doublers and Pockels cells as well as in samples having different orientations. It is recommended, therefore, that samples that have suffered surface damage be thoroughly inspected internally before being repolished and reused. Internal filamentary damage in LiNbO 3 is shown to be composed of a series of very fine nearly planar cracks, which intersect to form one or more long lines having diameter \approx 0.4 \mu . When illuminated with visible light, diffraction effects make these lines appear blurred and give the impression of a tube of damaged material. Scanning electron micrographs of surface damage are included in this paper in order to show the very different characteristics of entrance and exit face damage and to reveal the importance of thermal effects as at least one cause of laser-induced damage.

Nonlinear analog-to-digital converter

Abstract: A high speed nonlinear analog-to-digital converter for producing a nonlinear or logarithmic transfer function which utilizes a parallel bank of nonlinear comparators and a parallel bank of linear comparators. The effective gain of the linear comparators is varied depending upon the portion of the logarithmic scale selected by the nonlinear comparators. This variation in gain is accomplished by changing the reference voltage of the linear comparators to coincide with the region of the input range in which the signal lies. The data flow through the converter is timed such that the nonlinear comparators are working on a second sample while the linear comparators are working on the first sample. All data from a complete sample arrives at the output terminals simultaneously.

Array processor for digital computers

Abstract: A digital computer adapted to perform vector and matrix operations without detailed programs is disclosed. The dimensions of matrices or of vectors are entered as codes in reserved fields in successive instruction words and the computer's processor is made to be responsive to such codes to perform any required operations on the matrices or vectors to be processed.