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At least 919 records · Page 51
All sourcesNASA NTRSDOE OSTI
NASA NTRS1973

Tracking and Data Relay Satellite System configuration and tradeoff study. Volume 4: Space shuttle launched TDRSS. Part 2: Final Report, 22 August 1972 - 1 April 1973

Configuration data and design information for the space shuttle launched configuration is presented. The overall system definition, operations and control, and telecommunication service system including link budgets are discussed. A brief description of the user transceiver and ground station is presented. A final section includes a summary description of the TDR spacecraft and all the subsystems. The data presented are largely in tabular form.

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NASA NTRS1973

Early childhood education: Status trends, and issues related to electronic delivery

The status of, and trends and issues within, early childhood education which are related to the possibilities of electronic delivery of educational service are considered in a broader investigation of the role of large scale, satellite based educational telecommunications systems. Data are analyzed and trends and issues discussed to provide information useful to the system designer who wishes to identify and assess the opportunities for large scale electronic delivery in early childhood education.

Rothenberg, D.↗
NASA NTRS1973

Conceptual design study for a teleoperator visual system, phase 2

An analysis of the concept for the hybrid stereo-monoscopic television visual system is reported. The visual concept is described along with the following subsystems: illumination, deployment/articulation, telecommunications, visual displays, and the controls and display station.

Grant, C.↗
NASA NTRS1973

Coordination procedure for radio relay and communication satellite services

A global rain rate statistic model is used to link microwave propagation statistics to measurable rain statistics in order to develop international telecommunication site criteria for radio relay and communication satellite services that minimize interference between receivers and transmitters. This rain coordination procedure utilizes a rain storm cell size, a statistical description of the rainfall rate within the cell valid for most of the earth's surface, approximations between Raleigh scatter and constancy of precipitation with altitude, and an analytic relation between radar reflectivity and rain rate.

Eckerman, J.↗
NASA NTRS1972

Teleconferencing: Cost optimization of satellite and ground systems for continuing progressional education and medical services

A set of analytical capabilities that are needed to assess the role satellite communications technology will play in public and other services was developed. It is user oriented in that it starts from descriptions of user demand and develops the ability to estimate the cost of satisfying that demand with the lowest cost communications system. To ensure that the analysis could cope with the complexities of the real users, two services were chosen as examples, continuing professional education and medical services. Telecommunications costs are effected greatly by demographic factors, involving distribution of users in urban areas and distances between towns in rural regions. For this reason the analytical tools were exercised on sample locations. San Jose, California and Denver, Colorado were used to represent an urban area and the Rocky Mountain states were used to represent a rural region. In assessing the range of satellite system costs, two example coverage areas were considered, one appropriate to cover the contiguous forty-eight states, a second appropriate to cover about one-third that area.

Dunn, D.↗
NASA NTRS1973

A Delphi forecast of technology in education

The results are reported of a Delphi forecast of the utilization and social impacts of large-scale educational telecommunications technology. The focus is on both forecasting methodology and educational technology. The various methods of forecasting used by futurists are analyzed from the perspective of the most appropriate method for a prognosticator of educational technology, and review and critical analysis are presented of previous forecasts and studies. Graphic responses, summarized comments, and a scenario of education in 1990 are presented.

Robinson, B. E.↗
NASA NTRS1972

Current concepts for a tracking and data relay satellite system.

Description of two varieties of a tracking and data relay satellite system utilizing geosynchronous relay spacecraft to provide telecommunications service to user spacecraft in low earth orbit. These users are categorized by their earth return data rates. The described system varieties are the two versions of a low and medium data rate system whose definition study is now complete. One of these versions utilizes a spin-stabilized spacecraft, while the other employs a three-axis stabilized one. Some of the communication problems peculiar to these system varieties are discussed.

Clark, G. Q.↗
NASA NTRS1972

System design of the ATS-F RFI measurement experiment.

Description of the system design of an RFI measurement experiment regarding optimal sharing of the 5.925- to 6.425-GHz frequency band between the ATS-F synchronous satellite and terrestrial telecommunication systems. The parametric measurements made will include transmitted and received power levels, propagation-path loss and variations as a function of range, elevation angle, RF polarization, and geographical location of interference sources. The technical objectives of the C-band RFI experiment are outlined, a functional diagram of the total system for the RFI measurement experiment is presented, and the design features of the receiver RF and IF circuits, the filters and detectors, and the computer control are summarized. A basic RFI measurement plan is presented which defines and briefly states the measurement procedure, which involves a number of different measurement modes, each of which is described in detail.

Henry, V. F.↗
NASA NTRS1972

Satellite networks for education.

Consideration of satellite-based educational networking. The characteristics and structure of networks are reviewed, and pressures within the educational establishment that are providing motivation for various types of networks are discussed. A number of studies are cited in which networking needs for educational sectors and services are defined. The current status of educational networking for educational radio and television, instructional television fixed services, inter- and intrastate educational communication networks, computer networks, cable television for education, and continuing and proposed educational experiments using NASA's Applications Technology Satellites is reviewed. Possible satellite-based educational telecommunication services and three alternatives for implementing educational satellite systems are described. Some remarks are made concerning public policy aspects of future educational satellite system development.

Singh, J. P.↗
NASA NTRS1973

Preliminary design and simulations of a Shuttle-Attached Manipulator System.

The preliminary design of a Shuttle-Attached Manipulator System is based on two arms that are articulated at shoulder, elbow, and wrist. Details of manipulator design are considered, giving attention to arm reach, velocity, acceleration, torque, joint angular travel limits, control, crew systems and man-machine interface, and telecommunications. The results of man-in-the-loop simulations show the feasibility of grappling a representative space payload from the Shuttle using a long boom manipulator system. The task, however, is sufficiently difficult to require the full concentration of one operator who should be relieved of any other tasks while performing operations with the manipulator system.

Brodie, S. B.↗
NASA NTRS1971

Teleconferencing, an annotated bibliography, volume 3

In this annotated and indexed listing of works on teleconferencing, emphasis has been placed upon teleconferencing as real-time, two way audio communication with or without visual aids. However, works on the use of television in two-way or multiway nets, data transmission, regional communications networks and on telecommunications in general are also included.

Shervis, K.↗
NASA NTRS1972

Tracking and data relay satellite system configuration and tradeoff study. Volume 3: TDRSS configuration and data summary, part 1

A reference handbook of configuration data and design information is presented. It treats the overall system definition, operations and control, and telecommunication service system including link budgets. A brief description of the user transceiver and ground station is presented. A final section includes a summary description of the TDR spacecraft and all the subsystems. The data presented are largely in tabular form for easy reference.

Source record↗
NASA NTRS1972

Tracking and data relay satellite system configuration and tradeoff study. Volume 5: TDRS spacecraft design, part 1

A dual spin stabilized TDR spacecraft design is presented for low data rate (LDR) and medium data rate (MDR) user spacecraft telecommunication relay service. The relay satellite provides command and data return channels for unmanned users together with duplex voice and data communication channels for manned user spacecraft. TDRS/ground links are in the Ku band. Command links are provided at UHF for LDR users and S band for MDR users. Voice communication channels are provided at UHF/VHF for LDR users and at S band for MDR users. The spacecraft is designed for launch on the Delta 2914 with system deployment planned for 1978. This volume contains a description of the overall TDR spacecraft configuration, a detailed description of the spacecraft subsystems, a reliability analysis, and a product effectiveness plan.

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NASA NTRS1973

The Arctic data buoy. A system for environmental monitoring in the Arctic

An automated data buoy system for environmental monitoring in the Arctic was developed. The buoy is designed to operate for a minimum of 1 year providing position and environmental data through polar-orbiting satellite telecommunications. It can be deployed by a two or three man crew using a small aircraft. It is capable of operating in both free-floating and frozen-in situations. An experimental unit successfully completed a 5-month test at Fletcher's Ice Island (T-3) during the winter of 1971-72 and six units were deployed in the Arctic during the spring of 1972. Results to data have demonstrated the utility of the basic design, the effectiveness of the satellite communications, and the feasibility of deploying and operating a large array of such buoy systems in the Arctic Ocean.

Haugen, D. P.↗
NASA NTRS1973

Computer-aided communication satellite system analysis and optimization

The capabilities and limitations of the various published computer programs for fixed/broadcast communication satellite system synthesis and optimization are discussed. A satellite Telecommunication analysis and Modeling Program (STAMP) for costing and sensitivity analysis work in application of communication satellites to educational development is given. The modifications made to STAMP include: extension of the six beam capability to eight; addition of generation of multiple beams from a single reflector system with an array of feeds; an improved system costing to reflect the time value of money, growth in earth terminal population with time, and to account for various measures of system reliability; inclusion of a model for scintillation at microwave frequencies in the communication link loss model; and, an updated technological environment.

Stagl, T. W.↗
NASA NTRS1974

Coherent receiver employing nonlinear coherence detection for carrier tracking

The concept of nonlinear coherence employed in carrier tracking to improve telecommunications efficiency is disclosed. A generic tracking loop for a coherent receiver is shown having seven principle feedback signals which may be selectively added and applied to a voltage controlled oscillator to produce a reference signal that is phase coherent with a received carrier. An eighth feedback signal whose nonrandom components are coherent with the phase detected and filtered carrier may also be added to exploit the sideband power of the received signal. A ninth feedback signal whose nonrandom components are also coherent with the quadrature phase detected and filtered carrier could be additionally or alternatively included in the composite feedback signal to the voltage controlled oscillator.

Lindsey, W. C.↗
NASA NTRS1974

Analysis of the proposed utilization of TDRS system by the HEAO-C satellite

The primary function of the study was to assess the impact upon the HEAO telecommunications system of the proposed relay satellite-to-ground-link configuration. The system is designed to perform the function of most of the NASA ground tracking and communications network at a net cost savings for NASA.

Weathers, G.↗