Systems Engineering and Multidisciplinary Design Optimization Commons^™

Jeffrey Grant, Jeffrey Grant

Online Journal of Space Communication

Vice President and Chief Technical Officer of Astrolink, a joint venture of several communications companies

Edward Fitzpatrick, Edward Fitzpatrick

Online Journal of Space Communication

Vice President of Hughes Network Systems

Tom Brackey, Tom Brackey

Online Journal of Space Communication

Executive Director, Technical Operations for External Affairs, and Chief Scientist for internal technical matters,Hughes Space and Communications Company

Joseph Rothenberg, Joseph Rothenberg

Online Journal of Space Communication

NASA's Associate Administrator for Space Flight

Gerald Barna, Gerald Barna

Online Journal of Space Communication

Acting Deputy Director of the NASA Glenn Research Center

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 …