Systems and Communications Commons^™

Gerald Barna, Gerald Barna

Online Journal of Space Communication

Acting Deputy Director of the NASA Glenn Research Center

Joseph Rothenberg, Joseph Rothenberg

Online Journal of Space Communication

NASA's Associate Administrator for Space Flight

Advanced Shipboard Communications Demonstrations With Acts, Roy A. Axford, T. C. Jedrey, M. Rupar

Online Journal of Space Communication

For ships at sea, satellites provide the only option for high data rate (HDR), long haul communications. Furthermore the demand for HDR satellite communications (SATCOM) for military and commercial ships, and other offshore platforms is increasing. Presently the bulk of this maritime HDR SATCOM connectivity is provided via C-band and X-band. However, the shipboard antenna sizes required to achieve a data rate of, say T1 (1.544 Mbps) with present C-/X-band SATCOM systems range from seven to ten feet in diameter. This limits the classes of ships to which HDR services can be provided to those which are large enough to …

A Ka-Band High Data Rate Shipboard Satellite Terminal, M. Rupar, David Beering, D. Hoder

Online Journal of Space Communication

A fully articulated steerable shipboard satellite antenna system operating at Ka-band was developed by engineers from the Naval Research Laboratory (NRL), NASA's Glenn Research Center, and a number of industry partners. A series of tests conducted in October of 1998 on Lake Michigan achieved an unparalleled data rate transmission of 45 megabits per second (Mbps) between a moving vessel at sea and a fixed-earth station using NASA's Advanced Communications Technology Satellite (ACTS). Network and application layer tests ran concurrently with the data rate transmission trials, examining TCP/IP file transfers, video and voice transfer technologies, and Asynchronous Transfer Mode (ATM) techniques. …

Gigabit Satellite Network For Nasa's Advanced Communication Technology Satellite (Acts): Features, Capabilities, And Operations, M. Bergamo, D. Hoder

Online Journal of Space Communication

This paper describes the Gigabit Satellite Network (GSN) being developed under joint sponsorship of NASA and ARPA. The system will use the wide-band Satellite Switched Time Division Multiple Access (SS-TDMA) capability and hopping beam antennas of NASA's Advanced Communications Technology Satellite (ACTS). The GSN network will provide full-duplex SONET services over satellite at OC-3 (155.54 Mb/s) and OC-12 (622.078 Mb/s) rates. Typical applications will include connection of distributed SONET/ATM fiber "islands" over satellite, wide-area distributed supercomputer networking, high-definition digital TV, and high-speed file transfer.

The RF link consists of 30 GHz uplink and 20 GHz downlink signals transmitted using a …

Acts 118x Final Report High-Speed Tcp Interoperability Testing, W. Ivancic, M. Zernic, D. Hoder, D. Brooks, David Beering, A. Welch

Online Journal of Space Communication

With the recent explosion of the Internet and the enormous business opportunities available to communication system providers, great interest has developed in improving the efficiency of data transfer using the Transmission Control Protocol (TCP) of the Internet Protocol (IP) suite. The satellite system providers are interested in solving TCP efficiency problems associated with long delas and error-prone links. Similarly, the terrestrial community is interested in solving TCP problems over high-bandwidth links. Whereas the wireless community is intested in improving TCP performance over bandwidth constrained, error-prone links.

NASA realized that solutions had already been proposed for most of the problems associated …

A History Of The Improvement Of Internet Protocols Over Satellites Using Acts, M. Allman, S. Ostermann, H. Kruse

Online Journal of Space Communication

This paper outlines the main results of a number of ACTS experiments on the efficacy of using standard Internet protocols over long-delay satellite channels. These experiments have been jointly conducted by NASA's Glenn Research Center and Ohio University over the last six years.

The focus of our investigations has been the impact of long-delay networks with non-zero bit-error rates on the performance of the suite of Internet protocols. In particular, we have focused on the most widely used transport protocol, the Transmission Control Protocol (TCP), as well as several application layer protocols. This paper presents our main results, as well …

Nasa Acts Satellite: A Disaster Recovery Test, H. Kruse, D. Flournoy

Online Journal of Space Communication

In September 1993, NASA launched its long-awaited Advanced Communication Technology (ACTS) satellite. ACTS is a $500 million experimental all-digital spacecraft hosting a number of first-time technologies: on-board processing and switching, high-powered electronically hopping spot beams, adaptive rain-fade compensation and opening of the Ka frequency band.

Among the earliest of the tests on the new satellite was a NASA sponsored project conducted by Ohio University and its commercial partner, the Huntington National Bank. HNB is a $17 billion regional bank with 338 offices in fourteen states. Transactions on HNB's data networks currently travel on terrestrial T-1 lines. The Ohio University/HNB tests …

Survey Of Advanced Applications Over Acts, Robert Bauer, Paul Mcmasters

Online Journal of Space Communication

The Advanced Communications Technology Satellite (ACTS) system provided a national testbed that enabled advanced applications to be tested and demonstrated over a live satellite link. Of the applications that used ACTS, some offered unique advantages over current methods, while others simply could not be accommodated by conventional systems. The initial technical and experiments results of the program were reported at the 1995 ACTS Results Conference, in Cleveland, Ohio. Since then, the Experiments Program has involved 45 new experiments comprising 30 application experiments and 15 technology related experiments that took advantage of the advanced technologies and unique capabilities offered by ACTS. …

Propagation Effects Handbook For Satellite Systems Design, Louis J. Ippolito

Online Journal of Space Communication

This paper describes the latest edition of the NASA Propagation Effects Handbook for Satellite Systems Design and presents a summary of application of the handbook information to satellite link design and performance. NASA, which has supported a large part of the experimental work in radiowave propagation on space communications links, recognized the need for a reference handbook of this type, and initiated a program in the late 1970's to develop and update a document that will meet this need. The Fifth Edition provides, in a single document, an update to two previous NASA handbooks; the fourth edition of a handbook …

Special Effects: Antenna Wetting, Short Distance Diversity And Depolarization, Roberto J. Acosta

Online Journal of Space Communication

The Advanced Communication Technology Satellite (ACTS) communications system operates in the Ka frequency band. ACTS uses multiple, hopping, narrow beams and very small aperture terminal (VSAT) technology to establish a system availability of 99.5% for bit-error-rates of 5x 10-7 or better over the continental United States. In order maintain this minimum system availability in all US rain zones, ACTS uses an adaptive rain fade compensation protocol to reduce the impact of signal attenuation resulting from propagation effects. The purpose of this paper is to present the results of system and sub-system characterizations considering the statistical effects of system variances due …

Ka-Band System And Propagation Effects On System Performance, Roberto J. Acosta, Sandra Johnson

Online Journal of Space Communication

The Advanced Communication Technology Satellite (ACTS) is an experimental communications satellite system launched in September 1993. ACTS introduces many new technologies, including operation in the Ka frequency band. ACTS uses multiple hopping narrow beams and very small aperture terminal (VSAT) technology to establish a system availability of 99.5% for a bit-error-rates of 5x10-7 or better over the continental United States. In order to maintain a minimum system availability f 99.5% over all US rain zones ACTS uses an adaptive rain fade compensation protocol to reduce the impact of signal attenuation resulting from propagation effects. The purpose of this paper is …

Comparison Of Multiple Rain Attenuation Models With Three Years Of Ka Band Propagation Data Concurrently Taken At Eight Different Locations, Glenn S. Feldhake, Lynn Ailes-Sengers

Online Journal of Space Communication

In June 1996, Working Party 3M of the ITU-R presented research comparing the estimations of 10 rain attenuation models with the 186 station years of earth-space propagation data contained within the ITU-R database known as DBSG5. Now, twenty-one station years of new data taken exclusively in the Ka band (20.185 GHz and 27.505 GHz) across North America are measured against many of those same models. Results are presented both in terms of error statistics as well as in comparison to the ITU database results.

Rain Attenuation Model Comparison And Validation, Charles E. Mayer, Bradley E. Jaeger

Online Journal of Space Communication

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Ka-Band Propagation Modeling For Fixed Satellite Applications, Asoka Dissanayake

Online Journal of Space Communication

Propagation impairments produced by the troposphere are a limiting factor for the effective use of the 20/30 GHz frequency band. Use of smaller earth terminals, while very attractive for consumer and transportable applications, make it difficult to provide sufficient link margin for propagation related outages. In this context, reliable prediction of propagation impairments for low-availability systems becomes important. This paper addresses the issues related to predicting different types of propagation impairments as well as combining them together to determine the overall impact on satellite links over a wide range of outage probabilities.

A Prediction Model That Combines Rain Attenuation And Other Propagation Impairments Along Earth-Satellite Paths, Asoka Dissanayake, Jeremy Allnutt, Fatim Haidara

Online Journal of Space Communication

The rapid growth of satellite services using higher frequency bands such as the Ka-band has highlighted a need for estimating the combined effect of different propagation impairments. Many projected Ka-band services will use very small terminals and, for some, rain effects may only form a relatively small part of the total propagation link margin. It is therefore necessary to identify and predict the overall impact of every significant attenuating effect along any given path.

A procedure for predicting the combined effect of rain attenuation and several other propagation impairments along earth-satellite paths is presented. Where accurate models exist for some …

Acts Propagation Experiment: Experiment Design, Calibration, And Data Preparation And Archival, Robert K. Crane, Xuhe Wang, D. B. Westenhaver, Wolfhard J. Vogel

Online Journal of Space Communication

The National Aeronautics and Space Administration Advanced Communications Technology Satellite (ACTS) propagation experiment was designed to obtain slant-path attenuation statistics for locations within the United States and Canada for use in the design of low-margin Ka-band satellite communication systems. Experimenters at seven different locations have collected propagation data for more than two years. The propagation terminals used for the experiment were identical. A single preprocessing program was used by the experimenters to provide for automatic calibration, generation of attenuation histograms, and data archival. In this paper, the calibration procedures are described and estimates given for measurement accuracy.

ACTS provided beacons …

Ka-Band Propagation Measurements: An Opportunity With The Advanced Communications Technology Satellite (Acts), Robert Bauer

Online Journal of Space Communication

The Advanced Communications Technology Satellite (ACTS) was conceived at the National Aeronautics and Space Administration (NASA) as a follow-on program to its long history in satellite communications projects that have reduced the risk of developing new technologies that fall outside the sponsorship capability of the private sector.

To counter the foreign challenge that developed in the late 1970's to the once insuperable U.S. lead in this field, ACTS was developed to maintain the U.S. preeminence. Launched in September 1993 from the space shuttle, key technologies on ACTS include a multibeam antenna, a baseband processor, a 900-MHz wideband microwave switch matrix, …

Historical Development: Acts Technology, Richard Gedney, Ron Schertler, Frank Gargione

Online Journal of Space Communication

The following material has been extracted from "The Advanced Communications Technology Satellite" book by Richard Gedney, Ron Schertler and Frank Gargione.

Advanced Communications Technology Satellite (Acts): Design And On-Orbit Performance Measurements, Frank Gargione, R. Acosta, T. Coney, R. Krawczyk

Online Journal of Space Communication

The Advanced Communications Technology Satellite (ACTS), developed and built by Lockheed Martin Astro Space for the NASA Lewis Research Center, was launched in September 1993 on the Shuttle STS 51 mission. ACTS is a digital experimental communications test bed that incorporates gigahertz bandwidth transponders operating at Ka band, hopping spot beams, on-board storage and switching, and dynamic rain fade compensation. This paper describes the ACTS enabling technologies, the design of the communications payload, the constraints imposed on the spacecraft bus, and the measurements conducted to verify the performance of the system in orbit.

Historical Development: Acts Program Formulation, Richard Gedney, Ron Schertler, Frank Gargione

Online Journal of Space Communication

The following material has been extracted from "The Advanced Communications Technology Satellite" book by Richard Gedney, Ron Schertler and Frank Gargione.

Issue 2: From The Guest Editor, Frank Gargione

Online Journal of Space Communication

Guest editor introduction

White Paper Report: Needs In Space Education For The 21st Century—Research, Higher Education, Training And Public Policy, Randall Johnson, Joseph Pelton, Henry Hertzfeld, Don Flournoy, Hussein J. Hussein

Online Journal of Space Communication

May 2, 2003

A Forum Seeking Innovative Answers

• New Approaches to Higher Education and Training
• Distance Learning, Tele-education and the Internet
• Shared Research Facilities and New Approaches to Research
• Joint University Projects
• Multidisciplinary Needs and International Perspectives and Languages
• Space and Security Issues Related to Education
• How to Attract More Students to Higher Education in the Space Field
• How to Prepare Incoming Students More Effectively for College
• Wide Spread Survey on Space Education to Find Concerns and New Solutions

From The Industry: Yasunori Matogawa, Ph.D., Professor Of Space Communications At The Institute Of Space And Astronautical Science, Yasunori Matogawa

Online Journal of Space Communication

Dr. Yasunori Matogawa is Professor at the Institute of Space and Astronautical Science directly reporting to the Ministry of Education, Science, Culture, Sports and Technology. He is also in charge of supervising Kagoshima Space Center in Kyushu as Director General. Widely considered to be the man of space education in Japan, Dr. Matogawa is the President for the Japan Society for Aeronautical and Space Sciences. Internationally, he is well-known as the Chairman of the International Astronautical Federation. The interview was conducted at Sophia University, Japan with the assistance of Dr. Tsutomu Kanayama (Email: kanaya-t@hoffman.cc.sophia.ac.jp).

Students Interested In Satellite Communications Can Gain An Edge In The Job Market By Studying Science And Theory, Ben Chang

Online Journal of Space Communication

The mind has an extraordinary ability to see things that are hoped for, Arthur C. Clarke said in 1973. Years later he noted that it cost about $100, in terms of kilowatt-hours, to go to the moon, "whereas it costs about a billion dollars the way we've done it."

These two quotes from the grandfather of satellite communications and author of 2001: A SPACE ODYSSEY point to one of the primary qualities INTELSAT looks for in filling engineering positions: the ability to apply book knowledge to the practical aspects of satellite communications.

Model Curricula: University Of Texas Medical Branch

Online Journal of Space Communication

University of Texas Medical Branch UTMB/NASA Aerospace Medicine Residency

Model Curricula: University Of Oklahoma

Online Journal of Space Communication

University of Oklahoma Aerospace Engineering

Model Curricula: Space Foundation

Online Journal of Space Communication

The Space Foundation is a national non-profit organization advancing space awareness and space education.

The Space Foundation pursues the mission of vigorously advancing civil, commercial and national security space endeavors for a brighter future and supporting educational excellence through the excitement of space.

Model Curricula: Umea University, Carol Norberg

Online Journal of Space Communication

The town of Kiruna, lying 140 kilometres above the Arctic Circle in northernSweden, has for many years been considered the ‘‘space centre’’ of Sweden.The high latitude makes Kiruna an attractive base for international spaceresearch. This paper describes the practical-oriented Space EngineeringProgram run in Kiruna by the University of Umeå. The students on theprogram benefit from the expertise of resident and visiting space scientistsand engineers. The education is the only one of its kind in Sweden.

Model Curricula: Esa Telecom Training Programme

Online Journal of Space Communication

This paper describes the content of an e-training course on satellite communications prepared under contract to ESA and now available at the ESA Telecom User Support Office website. The contract to develop this online training was led by EADS Fleximage with significant contributions from a team of subcontractors including EADS Astrium, British Telecom Exact Technologies, ENSAE/ SUP'Aero and ISU. The course is divided into five modules covering the following areas in an animated and progressive way:

• Systems and Services
• Communication Link
• Networking
• Space Segment
• Earth Segment