A theory for the design of one-way and two-way phase-coherent communication systems - Phase- coherent tracking systems
Network analysis of theoretical design of one-way and two-way phase coherent satellite communication systems
Lindsey, W. C.↗
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Max '91 Workshop 2: Developments in Observations and Theory for Solar Cycle 22
Papers and observatory reports presented at the second workshop of the Max '91 program are compiled along with discussion group summaries and invited reviews. The four discussion groups addressed the following subjects: high-energy flare physics; coordinated magnetograph observations; flare theory and modeling; and Max '91 communications and coordination. A special session also took place on observations of Active Region 5395 and the associated flares of March 1989. Other topics covered during the workshop include the scientific objectives of solar gamma ray observations, the solar capabilities of each of the four instruments on the Gamma Ray Observatory, and access to Max '91 information.
Winglee, Robert M.↗
Guidelines for Creating and Using Abbreviations and Acronyms
The unchecked use of acronyms and initialisms in technical writing presents a huge obstacle to clarity and readability. Although technical communicators are certainly more aware of this problem than are the engineers, scientists, and managers with whom they work, they need concrete guidelines and at least a small degree of self-righteousness on this subject to help them cope with the onslaught. That acronyms frustrate communication is well founded in linguistic theory, not to mention common sense. Suggestions for mitigating their destructiveness include issues of audience, term selectivity, frequency and occasion of use, and aesthetics.
Miller, Diane F.↗
Quantum detection of coherent-state signals in the presence of noise
A general method for solving an important class of quantum detection problems will be presented and evaluated. The quantum theory for detecting pure states for communications purposes has been developed over two decades ago, however the mixed state problem representing signal plus noise states has received little attention due to its great complexity. Here we develop a practical model for solving the mixed-state problem using a discrete approximation to the coherent-state representation of signal plus noise density operators.
Quantum communication quantum detection↗
Modulation/demodulation techniques for satellite communications. Part 2: Advanced techniques. The linear channel
A theory is presented for deducing and predicting the performance of transmitter/receivers for bandwidth efficient modulations suitable for use on the linear satellite channel. The underlying principle used is the development of receiver structures based on the maximum-likelihood decision rule. The application of the performance prediction tools, e.g., channel cutoff rate and bit error probability transfer function bounds to these modulation/demodulation techniques.
Omura, J. K.↗
Modulation/demodulation techniques for satellite communications. Part 3: Advanced techniques. The nonlinear channel
A theory for deducing and predicting the performance of transmitter/receivers for bandwidth efficient modulations suitable for use on the nonlinear satellite channel is presented. The underlying principle used throughout is the development of receiver structures based on the maximum likelihood decision rule and aproximations to it. The bit error probability transfer function bounds developed in great detail in Part 4 is applied to these modulation/demodulation techniques. The effects of the various degrees of receiver mismatch are considered both theoretically and by numerous illustrative examples.
Omura, J. K.↗
Communication training for aircrews: A review of theoretical and pragmatic aspects of training program design
This study is the final report of a project studying methods of communications training applicable to both civilian and military aviation personnel, including multiperson teams or single pilot fixed wing or rotary wing aircraft. A review is provided of a number of theories proposed as relevant for producing training materials for improved communications. Criteria are given for evaluating the applicability of training programs to the aviation environment, and these criteria are applied to United Airlines' Resources Management Training, as well as to a number of commercially available general purpose training programs. The report considers in detail assertiveness training and grid management training, examining their theoretical background and attempts made to validate their effectiveness. It was found that there are substantive difficulties in assessing the effectiveness of both training programs, as well as problems with the theories underlying them. However, because the aviation environment offers unique advantages for studying the effectiveness of communications training, recommendations are made on the design of appropriate training programs and on procedures that might be used to validate them.
Linde, Charlotte↗
A theory of human error
Human error, a significant contributing factor in a very high proportion of civil transport, general aviation, and rotorcraft accidents is investigated. Correction of the sources of human error requires that one attempt to reconstruct underlying and contributing causes of error from the circumstantial causes cited in official investigative reports. A validated analytical theory of the input-output behavior of human operators involving manual control, communication, supervisory, and monitoring tasks which are relevant to aviation operations is presented. This theory of behavior, both appropriate and inappropriate, provides an insightful basis for investigating, classifying, and quantifying the needed cause-effect relationships governing propagation of human error.
Mcruer, D. T.↗
On the application of extreme-value statistics to command oriented problems
Extreme value theory for estimating statistical parameters of spacecraft communication systems
SPACECRAFT COMMUNICATION↗
Double error probability in differential PSK.
Double error probability in differentially coherent phase shift keyed communications systems, noting computerized simulation substantiation of theory
Oberst, J. F.↗
A unified theory of coherent digital systems which track Doppler frequency Interim technical report
Unified theory for design of optimum coherent digital communication systems
Weber, C. L.↗
NASA multidisciplinary research grant
Research is discussed in the multidisciplinary areas of space and planetary science; materials and radiation; systems, instrumentation, and structures; and technology and man. Highlights are identified as an alpha-recoil track method of archeological dating; infrared astronomical telescope; reaction rates data, semiconductor radiation detectors, and analysis of time-dependent systems; Gunn effect devices for microwave generation and detection, mode-locked lasers, and radiation theory; and the application of a satellite communication system to educational development. Detectors to be flown on Apollo 16 to measure heavy particle flux in the solar wind and to be part of the HEAO-A experiment on extremely heavy nuclei in cosmic rays were developed. The impact of the multidisciplinary research on university activities is described, and individual departmental reports are included.
Source record↗
Antennas and Propagation; Proceedings of the International Conference, 8th, Heriot-Watt Univeristy, Edinburgh, UK, Mar. 30 - Apr. 2, 1993. Vols. 1 & 2
Conference papers from sessions on the following topics are presented: satellite antennas; modal analysis of transmission line structures; fading and scintillation; microcellular; numerical analysis; Olympus; indoor mobile; mechanical aspects of satellite antennas; flat plate and printed antennas; fade counter measures; electromagnetic theory; feeds for satellites; antennas for personal communications; frequency selected surfaces; remote sensing; active patch antennas; antenna measurements; clear air/trans horizon; high frequency system and noise; rain attenuation and rain scatter; and high frequency direction finding.
Source record↗
Discrete-time demodulation of continuous-time signals.
Nonlinear stochastic estimation theory is applied to the problem of obtaining discrete-time demodulator structures for the common types of analog communication signals. A stochastic communication model is presented that can be treated with current results in estimation theory. Approximate algorithms are developed for the estimation problem that yield mathematically realizable receiver structures for the cases of AM, PC, and FM. The digital receivers yield performance characteristics that compare favorably with those of their analog counterparts.
Kelly, C. N.↗
A theory of human error
Human errors tend to be treated in terms of clinical and anecdotal descriptions, from which remedial measures are difficult to derive. Correction of the sources of human error requires an attempt to reconstruct underlying and contributing causes of error from the circumstantial causes cited in official investigative reports. A comprehensive analytical theory of the cause-effect relationships governing propagation of human error is indispensable to a reconstruction of the underlying and contributing causes. A validated analytical theory of the input-output behavior of human operators involving manual control, communication, supervisory, and monitoring tasks which are relevant to aviation, maritime, automotive, and process control operations is highlighted. This theory of behavior, both appropriate and inappropriate, provides an insightful basis for investigating, classifying, and quantifying the needed cause-effect relationships governing propagation of human error.
Mcruer, D. T.↗
Advances in Modeling Solar System Internet Structures and their Data Flows
With an ever-increasing presence in space, there is also an increasing burden on existing communications infrastructure. We are heading towards an inflection point where the traditional approach of scheduled, single-path communications for space will no longer be viable. One answer is Delay Tolerant Networking (DTN), which takes the once disparate system of point-to-point links and unifies them in a networked architecture, thereby making communications more scalable. However, much work remains for discovering and harnessing the underlying theory of DTN. For example, in the terrestrial setting the interplay between routing domains is well-understood, however this is not the case in DTNs. In this paper, we build up the fundamental foundations of DTN, with an emphasis on modeling time varying networks and data flows across them, with examples of cross-domain routing in a DTN. A lofty goal of DTN is to enable the so-called Solar System Internet (SSI), which implies a standardized and robust suite of protocols. These protocols include routing across disconnected networks using store, carry, and forward mechanisms, which is necessary due to the disconnections, delays, and mobility intrinsic to space networks. Due to these factors, each of which generalize traditional networking, there is a deep and rich theory of DTNs. Here we build off of past successes to broaden this theory while striving to keep actionable results a goal for future implementations and operations. The approach includes modeling the unicast, broadcast, and multicast communications using the language of hypergraphs, which capture the geometric properties of such networked communications algebraically. Also inherent to these networks is their time-varying nature, particularly given mobility, and hence we also cultivate modeling techniques that respect this time dependence. This leads us to develop models using tools from category theory and algebraic geometry, which provide a language well-suited to describing synchronization and optimization over such networks. We also introduce and study a novel generalization of curvature applicable to time-evolving networks, which provides quantitative controls on diffusion processes on the network. Because an interplanetary network would feature links with propagation delays the preclude discovery (feedback) mechanisms, they will always feature a scheduled component. However, it is beneficial to support discovery where possible. While DTNs do not yet have strong definitions for their analogues of autonomous systems or network areas, we show how to join dynamic and schedule-based routing domains, using the language of sheaves, which marks progress towards such definitions. We conclude with a discussion of the progress made, as well as suggestions for future work.
Delay Tolerant Networking↗
Analytic short period lunar and solar perturbations of artificial satellites
A short period luni-solar theory was generalized for application to arbitrary obliquity of the ecliptic and inclination of the moon's orbit to the ecliptic. Analytic first order lunar perturbations to the elements were derived. The theory is illustrated by an application to the communication satellite Intelsat 3F3.
Fisher, D.↗
Analytic short period lunar and solar perturbations of artificial satellites.
The short period luni-solar theory of Kozai is generalized for arbitrary obliquity of the ecliptic and inclination of the moon's orbit to the ecliptic. Analytic first order lunar perturbations to the elements are derived. The theory is illustrated by an application to the communication satellite Intelsat 3F3.
Fisher, D.↗