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At least 91 records · Page 5

Advanced Communications Technology Satellite (ACTS)

The benefits that will be offered by the NASA-sponsored communication spacecraft ACTS which is scheduled for launch in 1992 are described together with examples of demonstrations on proposed data, video, and voice applications supported by the advanced ACTS technologies. Compared to existing satellite service, the ACTS will provide lower cost, better service, greater convenience, and improved service reliability of telecommunications to customers around the world. In addition, the pioneering ACTS technology will provide many capabilities qualitatively different from those of current satellite systems, such as on-demand assignment, frequency reuse, and the flexible targeting of spot beams directly to the very-small-aperture terminals at customer premises.

Olmstead, Dean A.↗

Space Station Freedom attached payloads and commercialization

NASA's Space Station Freedom (SSF) attaches external payloads to its main truss structure via Attached Payload Accommodation Equipment (APAE); this equipment also provides access to such SSF resources as electrical power, command/control, and data handling. In orbit, APAE payloads are installed and maintained by a teleoperated robot or by an astronaut in EVA. Commercialization of EPAE will be accomplished by private companies concerned with the development of materials processing, earth resources and ocean resources monitoring, telecommunications, and industrial services. Attention is given to APAE user-integration activity.

Furio, N.↗

Scheduling the future NASA Space Network: Experiences with a flexible scheduling prototype

NASA's Space Network (SN) provides telecommunications and tracking services to low earth orbiting spacecraft. One proposal for improving resource allocation and automating conflict resolution for the SN is the concept of flexible scheduling. In this concept, each Payload Operations Control Center (POCC) will possess a Space Network User POCC Interface (SNUPI) to support the development and management of flexible requests. Flexible requests express the flexibility, constraints, and repetitious nature of the user's communications requirements. Flexible scheduling is expected to improve SN resource utilization and user satisfaction, as well as reduce the effort to produce and maintain a schedule. A prototype testbed has been developed to better understand flexible scheduling as it applies to the SN. This testbed consists of a SNUPI workstation, an SN scheduler, and a flexible request language that conveys information between the two systems. All three are being evaluated by operations personnel. Benchmark testing is being conducted on the scheduler to quantify the productivity improvements achieved with flexible requests.

Happell, Nadine↗

AdaNET services

MountainNet is a small firm which serves as a distribution center for AdaNET Services. These services include providing host systems and telecommunications for AdaNET, developing and supporting AdaNET Information Services, and developing a dynamic software inventory. AdaNET hosts are a Data General MV8000II and DEC VAX. Telecommunications are provided via the MountainNet private network and the Telenet public access dial network. Initially, the AdaNET Information Services will include software repositories, user communications and forums, software engineering information, bibliographic and library services, and an educational directory. The dynamic software inventory, which will become available in January 1990, will contain software engineering code and parts.

Digman, Michael↗

New applications for the EUTELTRACS service

The EUTELTRACS two-way Mobile Satellite Messaging and Automatic Satellite Position Reporting (ASPR) service is Europe's first commercially operated Mobile Satellite Service. It was introduced by the European Telecommunications Satellite Organization (EUTELSAT) for commercial service in 1991. The system is based on a centralized network architecture organized around a single hub station operated by EUTELSAT. Initially the system was designed with a close user group architecture enabling a mobile user to communicate exclusively with its own headquarters. This paper describes the new applications (design and tests prior to their introduction into service) especially developed for the European market and particularly the Double Hop Services opening the system to authorized external entities. In addition, the European Commission (EC) pilot demonstrations in which the EUTELTRACS system is involved are described.

Colcy, Jean-Noel↗

International organizations to enable world-wide mobile satellite services

Numbers of systems exist or have been proposed to provide world-wide mobile satellite services (MSS). Developers of these systems have formulated institutional structures they consider most appropriate for profitable delivery of these services. MSS systems provide niche services and complement traditional telecommunications networks; they are not integrated into world-wide networks. To be successful, MSS system operators must be able to provide an integrated suite of services to support the increasing globalization, interconnectivity, and mobility of business. The critical issue to enabling 'universal roaming' is securing authority to provide MSS in all of the nations of the world. Such authority must be secured in the context of evolving trends in international telecommunications, and must specifically address issues of standardization, regulation and organization. Today, only one existing organization has such world-wide authority. The question is how proponents of new MSS systems and services can gain similar authority. Securing the appropriate authorizations requires that these new organizations reflect the objectives of the nations in which services are to be delivered.

Anglin, Richard L., Jr.↗

Toward domain-specific design environments: Some representation ideas from the telecommunications domain

ACME is an experimental environment for investigating new approaches to modeling and analysis of system requirements and designs. ACME is built on and extends object-oriented conceptual modeling techniques and knowledge representation and reasoning (KRR) tools. The most immediate intended use for ACME is to help represent, understand, and communicate system designs during the early stages of system planning and requirements engineering. While our research is ostensibly aimed at software systems in general, we are particularly motivated to make an impact in the telecommunications domain, especially in the area referred to as Intelligent Networks (IN's). IN systems contain the software to provide services to users of a telecommunications network (e.g., call processing services, information services, etc.) as well as the software that provides the internal infrastructure for providing the services (e.g., resource management, billing, etc.). The software includes not only systems developed by the network proprietors but also by a growing group of independent service software providers.

Greenspan, Sol↗

Telecommunications Relay Support of the Mars Phoenix Lander Mission

The Phoenix Lander, first of NASA's Mars Scout missions, arrived at the Red Planet on May 25, 2008. From the moment the lander separated from its interplanetary cruise stage shortly before entry, the spacecraft could no longer communicate directly with Earth, and was instead entirely dependent on UHF relay communications via an international network of orbiting Mars spacecraft, including NASA's 2001 Mars Odyssey (ODY) and Mars Reconnaissance Orbiter (MRO) spacecraft, as well as ESA's Mars Express (MEX) spacecraft. All three orbiters captured critical event telemetry and/or tracking data during Phoenix Entry, Descent and Landing. During the Phoenix surface mission, ODY and MRO provided command and telemetry services, far surpassing the original data return requirements. The availability of MEX as a backup relay asset enhanced the robustness of the surface relay plan. In addition to telecommunications services, Doppler tracking observables acquired on the UHF link yielded an accurate position for the Phoenix landing site.

Edwards, Charles D., Jr.↗

Developing satellite communications for public service: Prospects in four service areas

The Public Service Satellite Consortium evaluated prospects for satellite telecommunications in four areas of the public service: the U.S. health care system, elementary and secondary education, American libraries, and that sector of the public service which is concerned with the provision of continuing education to health professionals. Three important conclusions were reached. First, throughout the public service there are three recurring needs: improved access, cost containment, and maintenance of quality. Appropriate application of communication satellite systems could ameliorate each of these concerns. Second, there appears to be an enormous latent demand for data communication services throughout the public service. The potential demand in 1982 to support requirements in hospital administration, library services and other information-retrieval activities, equipment maintenance, and environmental monitoring may be in excess of $300 million a year. Third, administrative applications of data communication networks show particular promise, especially in rural areas.

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The Mars Reconnaissance Orbiter mission operations: architecture and approach

The Mars Reconnaissance Orbiter (MRO) was launched on August 12, 2005 by an Atlas V launch vehicle from Cape Canaveral Air Force Station. MRO will carry a rich set of science instruments to Mars and provide global, regional survey, and targeted observations. In addition, a set of engineering instruments providing optical navigation, Ka band telecommunication and UHF relay services to future Mars missions are part of the MRO payload.

MRO↗

The Mars Reconnaissance Orbiter Mission Operations: Architecture and Approach

The Mars Reconnaissance Orbiter (MRO) was launched on August 12, 2005 by an Atlas V launch vehicle from Cape Canaveral Air Force Station. MRO will carry a rich set of science instruments to Mars and provide global, regional survey, and targeted observations. In addition, a set of engineering instruments providing optical navigation, Ka band telecommunication and UHF relay services to future Mars missions are part of the MRO payload. During the mission, the MRO operations teams are presented with two major challenges - unprecedented high data rate and data volumes, and complex science planning and resource sharing. MRO has the capability to communicate with earth at a maximum of six Megabits per second (> 50 times any previous Mars missions). With the current Deep Space Network (DSN) contact schedule of 19 eight-hour tracks per week, the baseline mission plan is for MRO to return 34 Terabits of raw science data during the two year primary science phase. Each of the science instruments has its unique requirements for global mapping, regional survey, and targeted observations. Some instruments prefer nadir-only observations, while others require off-nadir observations (especially for stereo viewing). The requirements from these Mars viewing instruments presented a significant challenge for the operations team to design the complex science planning and resource sharing/allocation process. This paper describes what MRO project is implementing to solve these challenges.

Mars Reconnaissance Orbiter (MRO)↗

Telecommunications, navigation and information management concept overview for the Space Exploration Initiative program

An overview is provided of the Space Exploration Initiative (SEI) concepts for telecommunications, information systems, and navigation (TISN), and engineering and architecture issues are discussed. The SEI program data system is reviewed to identify mission TISN interfaces, and reference TISN concepts are described for nominal, degraded, and mission-critical data services. The infrastructures reviewed include telecommunications for robotics support, autonomous navigation without earth-based support, and information networks for tracking and data acquisition. Four options for TISN support architectures are examined which relate to unique SEI exploration strategies. Detailed support estimates are given for: (1) a manned stay on Mars; (2) permanent lunar and Martian settlements; short-duration missions; and (4) systematic exploration of the moon and Mars.

Bell, Jerome A.↗

Asynchronous Transfer Mode Quality-of-Service Testing

In support of satellite-ATM interoperability, researchers at the NASA Lewis Research Center performed asynchronous transfer mode (ATM) quality-of-service experiments using MPEG-2 (ATM application layer 5, AAL5) over ATM over an emulated satellite link. The purpose of these experiments was to determine the free-space link quality necessary to use the ATM protocol to transmit high-quality multimedia information. The experimental results have been submitted to various International Telecommunications Union (ITU) study groups in order to improve and modify current standards and recommendations for the telecommunications industry. Quality-of-service parameters for Class I, stringent class requirements for ITU-T I.356 are currently being debated. The experimental results presented will help to establish these quality-of-service thresholds. This material will also be useful in the development of the ITU-R WP-4B's Draft Preliminary New Recommendation on the Transmission of Asynchronous Transfer Mode Traffic via Satellite (Rec. S.atm).

Ivancic, William D.↗

European Telecommunications Satellite II (EUTELSAT II)

EUTELSAT II is a regional public telecommunications system for Europe. The services which will be provided are telephone and television. The satellites will be placed at a geostationary orbit within the arcs of 6 degrees east to 19 degrees east or 26 degrees to 36 degrees east. The designed lifetime is 7 years. After separation of the satellites from the launch vehicles, telemetry, telecommand, and ranging will be performed within the S-band frequencies. After positioning of the satellite at its final geostationary orbit, the Ku-band telecommunication equipment will be activated. From this time on, all satellite control operations will be performed in Ku-band. The Deep Space Network (DSN) will support the transfer and drift orbit mission phases. The coverage will consist of the 26-m antennas at Goldstone and Canberra as prime support for the transfer and drift orbits. Maximum support will consist of a 7-day period, plus 14 days of contingency support. Information is given in tabular form for DSN support, frequency assignments, telemetry, command, and tracking support responsibility.

Laemmel, G.↗

Market assessment of photovoltaic power systems for agricultural applications in Morocco

Results of a month-long study in Morocco aimed at assessing the market potential for stand-alone photovoltaic systems in agriculture and rural service applications are presented. The following applications, requiring less than 15 kW of power, are described: irrigation, cattle watering, refrigeration, crop processing, potable water and educational TV. Telecommunications and transportation signalling applications, descriptions of power and energy use profiles, assessments of business environment, government and private sector attitudes towards photovoltaics, and financing were also considered. The Moroccan market presents both advantages and disadvantages for American PV manufacturers. The principle advantages of the Moroccan market are: a limited grid, interest in and present use of PV in communications applications, attractive investment incentives, and a stated policy favoring American investment. Disadvantages include: lack of government incentives for PV use, general unfamiliarity with PV technology, high first cost of PV, a well-established market network for diesel generators, and difficulty with financing. The market for PV in Morocco (1981-1986), will be relatively small, about 340 kwp. The market for PV is likely to be more favorable in telecommunications, transport signalling and some rural services. The primary market appears to be in the public (i.e., government) rather than private sector, due to financial constraints and the high price of PV relative to conventional power sector.

Steingass, H.↗

National law enforcement telecommunications network

Alternative approaches are analyzed to a National Law Enforcement Telecommunications Network (NALECOM) designed to service all state-to-state and state-to-national criminal justice communications traffic needs in the United States. Network topology options were analyzed, and equipment and personnel requirements for each option were defined in accordance with NALECOM functional specifications and design guidelines. Evaluation criteria were developed and applied to each of the options leading to specific conclusions. Detailed treatments of methods for determining traffic requirements, communication line costs, switcher configurations and costs, microwave costs, satellite system configurations and costs, facilities, operations and engineering costs, network delay analysis and network availability analysis are presented. It is concluded that a single regional switcher configuration is the optimum choice based on cost and technical factors. A two-region configuration is competitive. Multiple-region configurations are less competitive due to increasing costs without attending benefits.

Reilly, N. B.↗

Space Platform Technology

Study examines possibility of using few large platforms in space instead of many small satellites to provide communications and other services. Study was based in large measure on user survey. List of 31 potential services was presented to leading telecommunications firms (including carriers, programers, users and manufacturers). Both favorable and antagonistic viewpoints were solicited.

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