Geometry and First-order Error Statistics for Three- and Four-station Hyperbolic Fixes on a Spherical Earth
Geometry and First-order Error Statistics for Three- and Four-station Hyperbolic Fixes on a Spherical Earth

Author: Edward A. Lewis

Publisher:

Published: 1964

Total Pages: 96

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Certain fundamental geometric properties of hyperbolas and ellipses on the surface of a sphere are developed. A first-order theory is then presented for the random errors in the location of a point on a spherical earth, by the intersection of spherical hyperbolas physically determined by a time difference technique in which the individual errors are 'normally' distributed and uncorrelated. Two cases are treated: (a) Four time-measuring stations working as two independent pairs, and (b) Three time-measuring stations working on a common time-base. In both cases, the contours of equal error probability density are shown to be ellipses and their properties are discussed. In both cases the distribution of radial error without regard to direction is given by a generalized distribution function which contains the Rayleigh distribution as a special case. Using the general form, the most probable mean, root mean square, and median radial errors are obtained. The results are adaptable to include errors in ordinary direction finders as well as those of the hyperbolic type. Numerical examples are included. (Author).

Geometry and First-order Error Statistics for Three- and Four-station Hyperbolic Fixes on a Spherical Earth
Geometry and First-order Error Statistics for Three- and Four-station Hyperbolic Fixes on a Spherical Earth

Author: Edward A. Lewis

Publisher:

Published: 1964

Total Pages: 0

ISBN-13:

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Certain fundamental geometric properties of hyperbolas and ellipses on the surface of a sphere are developed. A first-order theory is then presented for the random errors in the location of a point on a spherical earth, by the intersection of spherical hyperbolas physically determined by a time difference technique in which the individual errors are 'normally' distributed and uncorrelated. Two cases are treated: (a) Four time-measuring stations working as two independent pairs, and (b) Three time-measuring stations working on a common time-base. In both cases, the contours of equal error probability density are shown to be ellipses and their properties are discussed. In both cases the distribution of radial error without regard to direction is given by a generalized distribution function which contains the Rayleigh distribution as a special case. Using the general form, the most probable mean, root mean square, and median radial errors are obtained. The results are adaptable to include errors in ordinary direction finders as well as those of the hyperbolic type. Numerical examples are included. (Author).

Molecular Structure of 2-(4'-amino-5'-azamethenyl Pyrimidyl)-3 Pentene-4-ol
Molecular Structure of 2-(4'-amino-5'-azamethenyl Pyrimidyl)-3 Pentene-4-ol

Author: N. F. Yannoni

Publisher:

Published: 1964

Total Pages: 4

ISBN-13:

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An X-ray analysis of the molecular and crystal structure of 2-(4'-amino-5'-azamethenyl pyrimidyl)-3 pentene-4-ol was recently completed. Significant results of this work include the determination of the structural parameters of the pyrimidine ring with an accuracy hitherto unavailable in the chemical literature, and the elucidation of a comprehensive system of hydrogen bonds which, in large part, are responsible for the molecular packing as it exists in the crystal. Each molecule participates in a total of six hydrogen bonds. Two amino hydrogen atoms and one hydroxyl hydrogen atom participate in hydrogen bonds to other molecules and three nitrogen atoms (two in the ring and one in the long side-chain) participate in hydrogen bonds which have the hydrogen atom chemically bound to adjacent molecules. (Author).

Earth-to-space Communications at Millimeter Wavelengths
Earth-to-space Communications at Millimeter Wavelengths

Author: Edward E. Altshuler

Publisher:

Published: 1965

Total Pages: 46

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It is expected that with the exploration of outer space, a requirement for high data rate earth-to-space communication channels will arise. A program to investigate the feasibility of using the millimeter-wave region of the spectrum for this application is presented. The theory of atmospheric attenuation resulting from losses due to absorption, scattering and refraction processes is reviewed and used to estimate propagation losses produced by atmospheric gases, clouds and precipitation. Curves of total atmospheric attenuation and noise level as a function of meteorological parameters and antenna elevation angle are also presented. A series of experiments designed to obtain as much information as possible on the limitations imposed by the atmosphere on millimeter-wave propagation is considered. Although experiments using natural celestial bodies such as the sun, moon, planets and galaxies as radio sources are emphasized, those which would utilize aircraft, rockets and satellites are also mentioned. Finally, the characteristics of a recently installed precision 29-ft antenna designed to operate at 35 Gc (wavelength = 8.6 mm) with a traveling-wave maser as a preamplifier for the radiometer are outlined along with the specific experiments for which this antenna system will be used. (Author).

Least Mean Square Error Analysis of PCM Transmission
Least Mean Square Error Analysis of PCM Transmission

Author: Ian T. Young

Publisher:

Published: 1964

Total Pages: 28

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Optimal energy distribution applied to a least mean square error criterion for PCM transmission is discussed. Comparisons are drawn between the optimized scheme and standard scheme for: (1) White Noise Channel (2) White Noise and Rayleigh Fading Channel. It is concluded that for few bit samples only small energy savings are attained. (Author).

A Method for Estimating Atmospheric Noise Amplitudes and Phase Errors in Quenched High-Q Receiving Circuits
A Method for Estimating Atmospheric Noise Amplitudes and Phase Errors in Quenched High-Q Receiving Circuits

Author: E. A. Lewis

Publisher:

Published: 1965

Total Pages: 50

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Very narrow-band quenched filters used for studying VLF radio signals differ from conventional narrow-band circuits in that both signal and atmospheric noise impulses cause only brief quasi-sinusoidal outputs instead of a prolonged ringing. The random overlapping of these short noise and signal bursts can cause errors in phase measurements. It is shown that the distribution of phase errors can be calculated from the amplitude distribution of the output noise envelope. The properties of the phase distribution are discussed in detail, the computation required in the general case is illustrated by means of a numerical example. A simple 'time-sequential' method for experimentally obtaining typical amplitude distributions is suggested. (Author).

A Program for the Solution of a Class of Geometric-analogy Intelligence-test Questions
A Program for the Solution of a Class of Geometric-analogy Intelligence-test Questions

Author: Thomas G. Evans

Publisher:

Published: 1964

Total Pages: 104

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The novel organization of the program in terms of figure descriptions, which are analyzed to find transformation rules, and rule descriptions, which are analyzed to find 'common generalizations' of pairs of transformation rules, has implications for the design of problem-solving programs and for machine learning. These implications are discussed at some length and suggestions are made for work on pattern-recognition and learning techniques based on ideas developed in the course of the present investigation.

Report on Research at AFCRL
Report on Research at AFCRL

Author: Air Force Cambridge Research Laboratories (U.S.)

Publisher:

Published: 1965

Total Pages: 322

ISBN-13:

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Summaries are given of research in the following fields: upper atmosphere physics, microwave physics, space physics, terrestrial sciences, optical physics, data sciences, meteorology, solid state, aerospace instrumentation.