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1

Public service satellite communications  

NASA Technical Reports Server (NTRS)

It is suggested that the high effective isotropic radiated power provided by high-power satellite transmitters and high-gain antennas could be used in conjunction with economical ground receivers to furnish public services in remote areas of the U.S. Applications to health care, education and public safety are mentioned. A system concept involving a communications satellite operating in the Ku-band (12-GHz down, 14-GHz up) and either 100/30 watt stationary earth terminals with 1-1.8 m antennas or mobile terminals with omnidirectional antennas is presented.

Wolff, E. A.

1978-01-01

2

Satellite communication for public services  

NASA Technical Reports Server (NTRS)

Public service programs using NASA's ATS-6 and CTS satellites are discussed. Examples include the ATS-6 Health and Education Telecommunications experimental program and the use of CTS to enable students in one university to take courses presented at another distant university. Possible applications of satellite communication systems to several areas of public service are described, and economic and political obstacles hindering the implementation of these programs are considered. It is suggested that a federally sponsored program demonstrating the utility of satellites accomodating a large number of small terminals is needed to encourage commercial satellite operations.

Cooper, R. S.; Redisch, W. N.

1977-01-01

3

A public service communications satellite user brochure  

NASA Technical Reports Server (NTRS)

The capabilities of a proposed communications satellite that would be devoted to experiments and demonstrations of various public services is described. A Public Service Communications Satellite study was undertaken at the NASA Goddard Space Flight Center (GSFC) to define the problems and opportunities of a renewed NASA role and the form such NASA involvement should take. The concept that has evolved has resulted from careful consideration of experiments that were already undertaken on existing satellites.

1977-01-01

4

Public Service Communications Satellite User Requirements Workshop  

NASA Technical Reports Server (NTRS)

Information on user requirements for public service communications was acquired to provide the basis of a study to determine the optimum satellite system to satisfy user requirements. The concept for such a system is described: Topics discussed included requirements for data and message services, elementary and secondary education, extension and continuing education, environmental communications, library services, medical education, medical services, public broadcasting, public safety, religious applications, state and local communications, and voluntary services. Information was also obtained on procedures to follow to make the transfer to commercial services.

Wolff, E. A.

1977-01-01

5

Mobile satellite communications in the Forest Service  

NASA Technical Reports Server (NTRS)

There are usually some places within a forest that do not have adequate communication coverage due to line-of-sight or other reasons. These areas are generally known by the foresters and radio technicians and allowances are made for that when working or traveling in those areas. However, when wildfire or other emergencies occur, communications are vital because wildfires can require hundreds of firefighters and cover thousands of acres. During these emergency operations, the existing communications are not adequate and complete radio systems are moved into the area for the conduct of fire communications. Incident command posts (ICPs) and fire camps are set up in remote locations and there is constant need for communications in the fire area and to agency headquarters and dispatch offices. Mobile satellite communications would be an ideal supplement to the Forest Service's current communications system in aiding forest fire control activities.

Warren, John R.

1988-01-01

6

Mobile satellite communications in the Forest Service  

NASA Astrophysics Data System (ADS)

There are usually some places within a forest that do not have adequate communication coverage due to line-of-sight or other reasons. These areas are generally known by the foresters and radio technicians and allowances are made for that when working or traveling in those areas. However, when wildfire or other emergencies occur, communications are vital because wildfires can require hundreds of firefighters and cover thousands of acres. During these emergency operations, the existing communications are not adequate and complete radio systems are moved into the area for the conduct of fire communications. Incident command posts (ICPs) and fire camps are set up in remote locations and there is constant need for communications in the fire area and to agency headquarters and dispatch offices. Mobile satellite communications would be an ideal supplement to the Forest Service's current communications system in aiding forest fire control activities.

Warren, John R.

1988-05-01

7

USDA Forest Service mobile satellite communications applications  

NASA Technical Reports Server (NTRS)

The airborne IR signal processing system being developed will require the use of mobile satellite communications to achieve its full capability and improvement in delivery timeliness of processed IR data to the Fire Staff. There are numerous other beneficial uses, both during wildland fire management operations or in daily routine tasks, which will also benefit from the availability of reliable communications from remote areas.

Warren, John R.

1990-01-01

8

Mobile satellite service communications tests using a NASA satellite  

NASA Technical Reports Server (NTRS)

Emerging applications of commercial mobile satellite communications include satellite delivery of compact disc (CD) quality radio to car drivers who can select their favorite programming as they drive any distance; transmission of current air traffic data to aircraft; and handheld communication of data and images from any remote corner of the world. Experiments with the enabling technologies and tests and demonstrations of these concepts are being conducted before the first satellite is launched by utilizing an existing NASA spacecraft.

Chambers, Katherine H.; Koschmeder, Louis A.; Hollansworth, James E.; ONeill, Jack; Jones, Robert E.; Gibbons, Richard C.

1995-01-01

9

Satellite communications in China  

Microsoft Academic Search

The current status of satellite communication technology in China is reviewed. Particular attention is given to satellite communication networks for public service and some specialized communication networks.

Guorui Chen; Warren Stutzman

1991-01-01

10

Satellite communications for the next generation telecommunication services and networks  

NASA Technical Reports Server (NTRS)

Satellite communications can play an important role in provisioning the next-generation telecommunication services and networks, provided the protocols specifying these services and networks are satellite-compatible and the satellite subnetworks, consisting of earth stations interconnected by the processor and the switch on board the satellite, interwork effectively with the terrestrial networks. The specific parameters and procedures of frame relay and broadband integrated services digital network (B-ISDN) protocols which are impacted by a satellite delay. Congestion and resource management functions for frame relay and B-ISDN are discussed in detail, describing the division of these functions between earth stations and on board the satellite. Specific onboard and ground functions are identified as potential candidates for their implementation via neural network technology.

Chitre, D. M.

1991-01-01

11

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

NASA Technical Reports Server (NTRS)

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.

1977-01-01

12

Laser Communication Demonstration System (LSCS) and Future Mobile Satellite Services  

NASA Technical Reports Server (NTRS)

The Laser Communications Demonstration System (LCDS) is a proposed in-orbit demonstration of high data rate laser communications technology conceived jointly by NASA and U.S. industry. The program objectives are to stimulate industry development and to demonstrate the readiness of high data rate optical communications in Earth Orbit. For future global satellite communication systems using intersatellite links (ISLs), laser communications technology can offer reduced mass , reduced power requirements, and increased channel bandwidths without regulatory restraint. This paper provides comparisons with radio systems and status of the program.

Chen, C. -C.; Lesh, J. R.

1995-01-01

13

Satellite communications experiment for the Ontario air ambulance service  

NASA Technical Reports Server (NTRS)

A satellite communications experiment was conducted to develop a reliable voice communications system between paramedics and doctors at certain larger medical centers. The experiment used INMARSAT's Atlantic Ocean Region satellite which provides coverage to the western border of Ontario. Forward downlink power from the satellite is in great demand, so two highly power-efficient modulation schemes were chosen for evaluation during the experiment. These were amplitude-companded single-sideband (ACSSB) and linear predictive coding in conjunction with DMSK modulation. Good performance with a signal to noise ratio of about 10 dB was demonstrated from many parts of the province with the evevation angle to the satellite ranging from five to twenty degrees and with the aircraft both in-flight and on the runway.

Butterworth, John S.

1988-01-01

14

Public service communications satellite. [health, education, safety and information transfer applications  

NASA Technical Reports Server (NTRS)

Health, education, public safety, and information transfer applications of public service communications satellites are discussed with particular attention to the use of communications satellites to improve rural health delivery. Health-care communications requirements are summarized. The communications system concept involves small inexpensive stationary, portable, and moving ground terminals which will provide communications between any two points in the U.S. with both fixed and moving terminals on a continuous 24-hour basis. User requirements, wavebands, and privacy techniques are surveyed.

Wolff, E. A.

1978-01-01

15

Satellite applications to electric-utility communications needs. [land mobile satellite service  

NASA Technical Reports Server (NTRS)

Significant changes in the Nation's electric power systems are expected to result from the integration of new technology, possible during the next decade. Digital communications for monitor and control, exclusive of protective relaying, are expected to double or triple current traffic. A nationwide estimate of 13 Mb/s traffic is projected. Of this total, 8 Mb/s is attributed to the bulk-power system as it is now being operated (4 Mb/s). This traffic could be accommodated by current communications satellites using 3- to 4.5-m-diameter ground terminals costing $35,000 to $70,000 each. The remaining 5-Mb/s traffic is attributed to new technology concepts integrated into the distribution system. Such traffic is not compatible with current satellite technology because it requires small, low-cost ground terminals. Therefore, a high effective isotropic radiated power satellite, such as the one being planned by NASA for the Land Mobile Satellite Service, is required.

Horstein, M.; Barnett, R.

1981-01-01

16

Satellite provided fixed communications services: A forecast of potential domestic demand through the year 2000: Volume 2: Main text  

NASA Technical Reports Server (NTRS)

Potential satellite-provided fixed communications services, baseline forecasts, net long haul forecasts, cost analysis, net addressable forecasts, capacity requirements, and satellite system market development are considered.

Kratochvil, D.; Bowyer, J.; Bhushan, C.; Steinnagel, K.; Kaushal, D.; Al-Kinani, G.

1983-01-01

17

Laser Communication Demonstration System (LCDS) and future mobile satellite services  

NASA Technical Reports Server (NTRS)

The Laser Communications Demonstration System (LCDS) is a proposed in-orbit demonstration of high data rate laser communications technology conceived jointly by NASA and U.S. industry. The program objectives are to stimulate industry development and to demonstrate the readiness of high data rate optical communications in Earth orbit. For future global satellite communication systems using intersatellite links, laser communications technology can offer reduced mass and power requirements and higher channel bandwidths without regulatory constraints. As currently envisioned, LCDS will consist of one or two orbiting laser communications terminals capable of demonstrating high data rate (greater than 750Mbps) transmission in a dynamic space environment. Two study teams led by Motorola and Ball Aerospace are currently in the process of conducting a Phase A/B mission definition study of LCDS under contracts with JPL/NASA. The studies consist of future application survey, concept and requirements definition, and a point design of the laser communications flight demonstration. It is planned that a single demonstration system will be developed based on the study results. The Phase A/B study is expected to be completed by the coming June, and the current results of the study are presented in this paper.

Chen, Chien-Chung; Wilhelm, Michael D.; Lesh, James R.

1995-01-01

18

Satellite communication services for Tibet autonomous region by domestic satellite in China  

Microsoft Academic Search

This article describes the factors to be considered, the type-selecting principles and the refinement of the prototype in construction of the Tibet thin-route satellite telecommunication network. Western China is the cradle of the culture and economic development of the country. It has vast territory, abundant resources and great potential. The application of satellite communication technology in our country has been

Bao-Kun Wu

1992-01-01

19

Use of communications. [satellite communication  

NASA Technical Reports Server (NTRS)

Progress in the field of satellite communications is reviewed, and useful services which may be provided by future satellite communications systems are considered. Recommendations are made with regard to mobile communications for use on land and at sea, position determination, mineral and energy exploration, the possibility of using electronic means to assist in main delivery, education and health-care experiments, and the use of satellite telecommunications to enhance the quality of life in rural areas by making available a full range of educational and entertainment programs. The needs of the amateur radio community are also considered.

1975-01-01

20

78 FR 14952 - Earth Stations Aboard Aircraft Communicating with Fixed-Satellite Service Geostationary-Orbit...  

Federal Register 2010, 2011, 2012, 2013

...Fixed-Satellite Service Geostationary-Orbit Space Stations AGENCY: Federal Communications...be authorized to communicate with GSO space stations of the FSS on a primary basis in the 11.7-12.2 GHz band (space-to-Earth), on an unprotected...

2013-03-08

21

Maritime terrestrial and satellite communications - Their relative role in the overall maritime radio-communication service in the coming decades  

Microsoft Academic Search

The considerations set forth in the present paper indicate that the maritime radio communications service of the future will be arrived at only after extensive international discussion in a number of fora, including IMCO and CCIR. With the arrival of satellite communications, this process of consultation is at a watershed. It is time now for ideas to be discussed. Gradually

S. R. Temple

1978-01-01

22

78 FR 14920 - Earth Stations Aboard Aircraft Communicating With Fixed-Satellite Service Geostationary-Orbit...  

Federal Register 2010, 2011, 2012, 2013

...Fixed-Satellite Service Geostationary-Orbit Space Stations AGENCY: Federal Communications...Service (FSS) geostationary-orbit (GSO) space stations operating in the 10.95-11...45-11.7 GHz, 11.7-12.2 GHz (space-to-Earth or downlink) and...

2013-03-08

23

Optimization of orbital assignment and specification of service areas in satellite communications  

NASA Technical Reports Server (NTRS)

The mathematical nature of the orbital and frequency assignment problem for communications satellites is explored, and it is shown that choosing the correct permutations of the orbit locations and frequency assignments is an important step in arriving at values which satisfy the signal-quality requirements. Two methods are proposed to achieve better spectrum/orbit utilization. The first, called the delta S concept, leads to orbital assignment solutions via either mixed-integer or restricted basis entry linear programming techniques; the method guarantees good single-entry carrier-to-interference ratio results. In the second, a basis for specifying service areas is proposed for the Fixed Satellite Service. It is suggested that service areas should be specified according to the communications-demand density in conjunction with the delta S concept in order to enable the system planner to specify more satellites and provide more communications supply.

Wang, Cou-Way; Levis, Curt A.; Buyukdura, O. Merih

1987-01-01

24

Land mobile communications satellite  

NASA Astrophysics Data System (ADS)

The economic value and salient technical and operational characteristics of a European Land Mobile Communication Satellite (LMCS) to complement and supplement the demand for mobile services of Western European countries in the 1995 to 2005 time frames were assessed. A significant future expansion of demand for LCMS services on the part of the public is anticipated. Important augmentations of current service capabilities could be achieved by a satellite service, improving the overall system performances and/or assisting the PTT's in containing their investments in the required infrastructure. The satellite service itself could represent a profitable revenue producer.

Carnebianca, C.; Pavesi, B.; Tuozzi, A.

1986-09-01

25

An approach to effective UHF (S/L band) data communications for satellite Personal Communication Service (PCS)  

NASA Technical Reports Server (NTRS)

Reliable signaling information transfer is fundamental in supporting the needs of data communication PCS via LMS (Land Mobile Service) SSs (satellite systems). The needs of the system designer can be satisfied only through the collection of media information that can be brought to bear on the pertinent design issues. We at ISI hope to continue our dialogue with fading media experts to address the unique data communications needs of PCS via LMS SSs.

Hayase, Joshua Y.

1995-01-01

26

Radio determination satellite service  

Microsoft Academic Search

The capabilities and measured performance of a geosynchronous satellite-based service called the radio determination satellite service (RDSS), which operates at radio frequencies allocated by the International Telecommunications Union (ITU) and is licensed in the United States by the Federal Communications Commission (FCC), are discussed. Plans for both improvement in capability and expansion to nearly global coverage are described. Since RDSS

Robert D. Briskman

1990-01-01

27

Telecom 1 - A national communication satellite for domestic and business services  

NASA Astrophysics Data System (ADS)

The French Telecom 1 satellite telecommunications project and the services to be provided by it are surveyed. Telecom 1 will comprise operational and spare satellites located in GEO at 4 and 7 deg W and operating in the 14/12 and 6/4-GHz bands, permanent receive-transmit stations for business data and telephone links, and both permanent receive-only and portable transmit-only stations for video-transmission services. The satellite communications payload includes six 36-MHz 20-W TWT transponders for either video or data transmission at 14/12 GHz and four 6/4-GHz transponders for telephone and video service to the Caribbean and Indian Ocean departments. A demand-assignment TDMA system provides data transmission at 2.4 kbit/s to 2 Mbit/s with nonpermanent links and variable network structure.

Lombard, D.; Rancy, F.; Rouffet, D.

28

Study of spread spectrum multiple access systems for satellite communications with overlay on current services  

NASA Technical Reports Server (NTRS)

The feasibility of using spread spectrum techniques to provide a low-cost multiple access system for a very large number of low data terminals was investigated. Two applications of spread spectrum technology to very small aperture terminal (VSAT) satellite communication networks are presented. Two spread spectrum multiple access systems which use a form of noncoherent M-ary FSK (MFSK) as the primary modulation are described and the throughput analyzed. The analysis considers such factors as satellite power constraints and adjacent satellite interference. Also considered is the effect of on-board processing on the multiple access efficiency and the feasibility of overlaying low data rate spread spectrum signals on existing satellite traffic as a form of frequency reuse is investigated. The use of chirp is examined for spread spectrum communications. In a chirp communication system, each data bit is converted into one or more up or down sweeps of frequency, which spread the RF energy across a broad range of frequencies. Several different forms of chirp communication systems are considered, and a multiple-chirp coded system is proposed for overlay service. The mutual interference problem is examined in detail and a performance analysis undertaken for the case of a chirp data channel overlaid on a video channel.

Ha, Tri T.; Pratt, Timothy

1989-01-01

29

An overview of the technical design of MSAT mobile satellite communications services  

NASA Astrophysics Data System (ADS)

The Canadian MSAT mobile satellite communications system is being implemented in cooperation with the American Mobile Satellite Consortium (AMSC). Two satellites are to be jointly acquired and each satellite is expected to backup the other. This paper describes the technical concepts of the services to be offered and the baseline planning of the infrastructure for the ground segment. MSAT service requirements are analyzed for mobile radio, telephone, data, and aeronautical services. The MSAT system will use nine beams in a narrow range of L-band frequencies with frequency reuse. Beams may be added to cover flight information areas in the Atlantic and Pacific oceans. The elements of the network architecture are: a network control centre, data hub stations, gateway stations, base stations, mobile terminals, and a signalling system to interconnect the elements of the system. The network control center will manage the network and allocate space segment capacity; data hub stations will support a switched packet mobile data service; the gateway stations will provide interconnection to the public telephone system and data networks; and the base stations will support private circuit switched voice and data services. Several alternative designs for the signalling system are described.

Davies, N. George

30

Wide-area technologies and services in the Trans-Pacific High Data Rate (HDR) satellite communications experiments  

NASA Technical Reports Server (NTRS)

This paper describes the technologies and services used in the experiments and demonstrations using the Trans-Pacific high data rate satellite communications infrastructure, and how the environment tasked protocol adaptability, scalability, efficiency, interoperability, and robustness.

Hsu, E.; Hung, C.; Kadowaki, N.; Yoshimura, N.; Takahashi, T.; Shopbell, P.; Walker, G.; Wellnitz, D.; Gary, P.; Clark, G.; Yoshikawa, M.; desJardins, R.; Gill, M.; Tatsumi, H.

2000-01-01

31

Business use of satellite communications.  

PubMed

The development of satellite communications over the past two decades has been very rapid. At the same time, space and electronics technologies have progressed sufficiently to allow satellite systems to keep pace with user requirements and to expand in several dimensions, including capacity, coverage, performance, reliability, and variety of services. The principal services provided by satellite systems have been long-distance trunks for telephone circuits and television program distribution. Recently, data transmission and network services have been added to meet emerging requirements for "office of the future" and other business applications. Data services are now expected to be the most rapidly expanding element of satellite communications. PMID:17747848

Edelson, B I; Cooper, R S

1982-02-12

32

Maritime satellite communication and navigation  

NASA Astrophysics Data System (ADS)

The contribution of satellite services to improving maritime safety, covering navigation as well as safety and distress communication, is discussed. The availability and accessibility of these services must be ascertained through international agreements. Satellite services will play an essential role for the electronic sea chart display. International carriage requirements and performance standards are necessary for the relevant equipment on board ships. New generic mobile satellite services will also be of relevance for maritime communication. As far as safety and distress communication is concerned, government agreements are necessary.

Ehlers, Peter

1992-07-01

33

Satellite Communications for U.S. Schools; A Proposed Public Service Offering by Private Business.  

ERIC Educational Resources Information Center

The Federal Communications Commission has asked that companies seeking authorization to construct and operate communications satellite facilities for multi-purpose commercial uses in the United States give consideration to the communications needs of schools. In response to this request, MCI Lockheed Satellite Corporation proposes a low-cost…

Krause, Lloyd I.

34

Communications satellites - The experimental years  

NASA Technical Reports Server (NTRS)

Only eight years after the launc of Sputnik-1 by the Soviet Union, the first commercial satellite, 'Early Bird', entered service. In just twelve years commercial satellite service extended around the earth and became profitable. The reasons for the successful development of the communications satellite services in a comparatively short time are considered. These reasons are related to the presence of three ingredients, taking into account technology to create the system, communications requirements to form a market, and a management structure to implement the system. The formation of the concept of using earth orbiting satellites for telecommunications is discussed. It is pointed out that the years from 1958 to 1964 were the true 'experimental years' for satellite communications. The rapid development of technology during this crucial period is described, giving attention to passive satellites, active systems, and development satellites.

Edelson, B. I.

1983-01-01

35

Communications satellites - The experimental years  

NASA Astrophysics Data System (ADS)

Only eight years after the launc of Sputnik-1 by the Soviet Union, the first commercial satellite, 'Early Bird', entered service. In just twelve years commercial satellite service extended around the earth and became profitable. The reasons for the successful development of the communications satellite services in a comparatively short time are considered. These reasons are related to the presence of three ingredients, taking into account technology to create the system, communications requirements to form a market, and a management structure to implement the system. The formation of the concept of using earth orbiting satellites for telecommunications is discussed. It is pointed out that the years from 1958 to 1964 were the true 'experimental years' for satellite communications. The rapid development of technology during this crucial period is described, giving attention to passive satellites, active systems, and development satellites.

Edelson, B. I.

1983-10-01

36

Communications satellite systems capacity analysis  

NASA Technical Reports Server (NTRS)

Analog and digital modulation techniques are compared with regard to efficient use of the geostationary orbit by communications satellites. Included is the definition of the baseline systems (both space and ground segments), determination of interference susceptibility, calculation of orbit spacing, and evaluation of relative costs. It is assumed that voice or TV is communicated at 14/11 GHz using either FM or QPSK modulation. Both the Fixed-Satellite Service and the Broadcasting-Satellite Service are considered. For most of the cases examined the digital approach requires a satellite spacing less than or equal to that required by the analog approach.

Browne, L.; Hines, T.; Tunstall, B.

1982-01-01

37

Satellite communication antenna technology  

NASA Technical Reports Server (NTRS)

A general overview of current technology in the field of communication satellite antennas is presented. Among the topics discussed are: the design of multiple beam systems; frequency reuse; and polarization control of antenna measurements. Consideration is also given to: contour beam synthesis; dual shaped reflector synthesis; beam shaping; and offset reflector design. The applications of the above technologies to present and future generations of communications satellites is considered, with emphasis given to such systems as: the Intelsats; the Defense Satellite Communications System, (DSCS-III); Satellite Business System (SBS), and Comstar.

Mittra, R. (editor); Imbriale, W. A. (editor); Maanders, E. J. (editor)

1983-01-01

38

Digital satellite communications  

NASA Astrophysics Data System (ADS)

The use of satellite communications in point-to-multipoint transmission of data is studied. The theory, systems, and equipment for satellite communications are described. The topics of satellite orbits, satellite construction, earth station equipment, and the analysis of the satellite link are discussed. Different types of digital modulation for carrier transmission, and techniques for enhancing the transmission capacity, such as digital speech interpolation and demand assignment, are examined. Techniques and equipment for performing the multiple access-broadcasting functions including FDMA, TDMA, DAMA, CDMA, and random access are considered.

Ha, T. T.

1986-06-01

39

IRIDIUM(R) aeronautical satellite communications  

Microsoft Academic Search

The ever-increasing demand to stay in touch, to be able to communicate anywhere and anytime, has created a market for Low Earth Orbit (LEG) satellite communications services such as the Iridium System. The Iridium satellite communications network is being developed to support the needs of the passenger, the cabin crew and the flight crew. Iridium Communications LLC owns a network

P. W. Lemme; S. M. Glenister; A. W. Miller

1998-01-01

40

Odyssey personal communications satellite system  

NASA Technical Reports Server (NTRS)

The spectacular growth of cellular telephone networks has proved the demand for personal communications. Large regions of the world are too sparsely populated to be economically served by terrestrial cellular communications. Since satellites are well suited to this application, TRW filed with the FCC on May 31, 1993 for the Odyssey construction permit. Odyssey will provide high quality wireless communication services worldwide from satellites. These services will include: voice, data, paging, and messaging. Odyssey will be an economical approach to providing communications. A constellation of 12 satellites will be orbited in three, 55 deg. inclined planes at an altitude of 10,354 km to provide continuous coverage of designated regions. Two satellites will be visible anywhere in the world at all times. This dual visibility leads to high line-of-sight elevation angles, minimizing obstructions by terrain, trees and buildings. Each satellite generates a multibeam antenna pattern that divides its coverage area into a set of contiguous cells. The communications system employs spread spectrum CDMA on both the uplinks and downlinks. This signaling method permits band sharing with other systems and applications. Signal processing is accomplished on the ground at the satellite's 'Gateway' stations. The 'bent pipe' transponders accommodates different regional standards, as well as signaling changes over time. The low power Odyssey handset will be cellular compatible. Multipath fade protection is provided in the handset.

Spitzer, Christopher J.

1993-01-01

41

System considerations, projected requirements and applications for aeronautical mobile satellite communications for air traffic services  

NASA Technical Reports Server (NTRS)

The projected application and requirements in the near term (to 1995) and far term (to 2010) for aeronautical mobile services supporting air traffic control operations are addressed. The implications of these requirements on spectrum needs, and the resulting effects on the satellite design and operation are discussed. The U.S. is working with international standards and regulatory organizations to develop the necessary aviation standards, signalling protocols, and implementation methods. In the provision of aeronautical safety services, a number of critical issues were identified, including system reliability and availability, access time, channel restoration time, interoperability, pre-emption techniques, and the system network interfaces. Means for accomplishing these critical services in the aeronautical mobile satellite service (AMSS), and the various activities relating to the future provision of aeronautical safety services are addressed.

Mcdonald, K. D.; Miller, C. M.; Scales, W. C.; Dement, D. K.

1990-01-01

42

Experiment In Aeronautical-Mobile/Satellite Communication  

NASA Technical Reports Server (NTRS)

Report describes study of performance of digital mobile/satellite communication terminals of advanced design intended for use in ground stations and airplanes in aeronautical-mobile service. Study was collaboration of NASA, Federal Aviation Administration (FAA), Communications Satellite Corp. (COMSAT), and International Maritime Satellite System (INMARSAT).

Jedrey, Thomas C.; Lay, Norman E.; Dessouky, Khaled

1992-01-01

43

Communication satellite technology trends  

NASA Technical Reports Server (NTRS)

A chronology of space-Earth interconnectivity is presented. The Advanced Communications Technology Satellite (ACTS) system, Land Mobile Satellite, space-Earth antennas, impact of antenna size on coverage, intersatellite links are outlined. This presentation is represented by graphs and charts only.

Cuccia, Louis

1986-01-01

44

Amateur Radio Satellite Communications.  

ERIC Educational Resources Information Center

The Amateur Radio Satellite Communications project had, as its goal, the assembly of an amateur radio satellite station in a high school physics classroom. Specific objectives were to provide: (1) a special source of interest as a motivator for attracting students and building public relations; (2) a center of interest as a motivator for the study…

Koch, David P.

45

Iridium(R) aeronautical satellite communications  

Microsoft Academic Search

The ever-increasing demand to stay in touch, to be able to communicate anywhere and anytime, has created a market for low Earth orbit (LEO) satellite communications services such as the Iridium system. The Iridium satellite communications network is being developed to support the needs of the passenger, the cabin crew and the flight crew for: aeronautical public correspondence (APC); aeronautical

P. W. Lemme; S. M. Glenister; A. W. Miller

1999-01-01

46

The 18 and 30 GHz fixed service communications satellite system study. [to determine the cost and performance characteristics  

NASA Technical Reports Server (NTRS)

The use of the 18 and 30 GHz bands for fixed service satellite communications is examined. The cost and performance expected of 18 and 30 GHz hardware is assessed, selected trunking and direct to user concepts are optimized, and the cost of these systems are estimated. The effect of rain attenuation on the technical and economic viability of the system and methods circumventing the problem are discussed. Technology developments are investigated and cost estimates of these developments are presented.

Bronstein, L. M.

1979-01-01

47

Millimeter wave communication satellite concepts  

NASA Technical Reports Server (NTRS)

Methodology has been developed for identifying viable and appropriate technologies for future NASA millimeter wave research as based upon the technical requirements of potential space communication services. Applicability of the methodology has been verified through its use with two conceptual communications systems. The subsystem cost and weight models are the appropriate level of detail for this study. Application of the methodology to the detailed design of a satellite system would require further model refinement.

Holland, L. D.; Hilsen, N. B.; Wallace, R. W.; Stevens, G.

1978-01-01

48

Demand for satellite-provided domestic communications services up to the year 2000  

NASA Technical Reports Server (NTRS)

Three fixed service telecommunications demand assessment studies were completed for NASA by The Western Union Telegraph Company and the U.S. Telephone and Telegraph Corporation. They provided forecasts of the total U.S. domestic demand, from 1980 to the year 2000, for voice, data, and video services. That portion that is technically and economically suitable for transmission by satellite systems, both large trunking systems and customer premises services (CPS) systems was also estimated. In order to provide a single set of forecasts a NASA synthesis of the above studies was conducted. The services, associated forecast techniques, and data bases employed by both contractors were examined, those elements of each judged to be the most appropriate were selected, and new forecasts were made. The demand for voice, data, and video services was first forecast in fundamental units of call-seconds, bits/year, and channels, respectively. Transmission technology characteristics and capabilities were then forecast, and the fundamental demand converted to an equivalent transmission capacity. The potential demand for satellite-provided services was found to grow by a factor of 6, from 400 to 2400 equivalent 36 MHz satellite transponders over the 20-year period. About 80 percent of this was found to be more appropriate for trunking systems and 20 percent CPS.

Stevenson, S.; Poley, W.; Lekan, J.; Salzman, J. A.

1984-01-01

49

Public service communications  

NASA Technical Reports Server (NTRS)

The purpose of the paper is to construct, for detailed analysis, satellite and terrestrial communications delivery system models. Attention is given to the Public Service Communications Delivery System Architectural Study, that takes advantage of the extensive experience which exists among the public service experimenters. The Application Test Pilot is examined, which is a program designed to help awareness, in a practical sense, of the technology available and by the users innovative talents, adapts the technology to solve their problems.

Whalen, A. A.

1979-01-01

50

Satellite Communications Using Commercial Protocols  

NASA Technical Reports Server (NTRS)

NASA Glenn Research Center has been working with industry, academia, and other government agencies in assessing commercial communications protocols for satellite and space-based applications. In addition, NASA Glenn has been developing and advocating new satellite-friendly modifications to existing communications protocol standards. This paper summarizes recent research into the applicability of various commercial standard protocols for use over satellite and space- based communications networks as well as expectations for future protocol development. It serves as a reference point from which the detailed work can be readily accessed. Areas that will be addressed include asynchronous-transfer-mode quality of service; completed and ongoing work of the Internet Engineering Task Force; data-link-layer protocol development for unidirectional link routing; and protocols for aeronautical applications, including mobile Internet protocol routing for wireless/mobile hosts and the aeronautical telecommunications network protocol.

Ivancic, William D.; Griner, James H.; Dimond, Robert; Frantz, Brian D.; Kachmar, Brian; Shell, Dan

2000-01-01

51

47 CFR 25.225 - Geographic Service Requirements for 17/24 GHz Broadcasting Satellite Service.  

Code of Federal Regulations, 2010 CFR

...Service. 25.225 Section 25.225 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) COMMON CARRIER SERVICES SATELLITE COMMUNICATIONS Technical Standards § 25.225 Geographic Service Requirements for...

2010-10-01

52

Business use of satellite communications  

NASA Astrophysics Data System (ADS)

The development, systems technology, and future applications of digital transmission systems for business use of satellite systems are explored. Intelsat currently has 22 satellites in space, applied mostly to data, telephone, and television transmission. An all digital communications network called the Integrated Services Digital Network is replacing the former, analog, systems with wideband digital transmission for voice, data, video, and industrial control information, with domestic satellites serving as the central node of transmissions in a service area. The digital systems are faster than the analog systems, and the U.S. Postal Service is developing an electronic mail system with six other countries. Various magazines are now teleprinted in various locations from broadcasts from a central source, and chain stores are employing data transmission for centralized management, inventory, and procurement.

Edelson, B. I.; Cooper, R. S.

1982-02-01

53

A new wave of communication satellites  

NASA Technical Reports Server (NTRS)

Satellites provide at present telephone, television, data, and business services on a national, regional, and international scale, and the geostationary arc has become crowded at C-band (6/4 GHz) and Ku-band (14/11 GHz) frequencies. The evolution and the present state of satellite communications are discussed along with details regarding the development of direct broadcast satellites, the position of Canada with respect to satellite communications, Japanese developments, ESA and Eutelsat, aspects of collaboration between France and Germany regarding communications satellites, the United Kingdom, and the Nordic countries.

Lovell, R. R.; Cuccia, C. L.

1984-01-01

54

A new wave of communication satellites  

NASA Astrophysics Data System (ADS)

Satellites provide at present telephone, television, data, and business services on a national, regional, and international scale, and the geostationary arc has become crowded at C-band (6/4 GHz) and Ku-band (14/11 GHz) frequencies. The evolution and the present state of satellite communications are discussed along with details regarding the development of direct broadcast satellites, the position of Canada with respect to satellite communications, Japanese developments, ESA and Eutelsat, aspects of collaboration between France and Germany regarding communications satellites, the United Kingdom, and the Nordic countries.

Lovell, R. R.; Cuccia, C. L.

1984-03-01

55

Overview of commercial satellite communications  

NASA Astrophysics Data System (ADS)

A brief history of communications satellites is presented, taking into account the launching of Sputnik 1 in October 1957, the Explorer 1 in January of 1958, the launch of the Score as the world's first active communications satellite in December 1958, the Communications Satellite Act in 1962, and the launch of 'Early Bird' in 1964. The Intelsat satellites are considered along with maritime satellite communications, the U.S. domestic satellite systems, Alaskan satellite communications, cable television, broadcast TV stations, print media, the hotel/motel industry as a large market for satellite communications terminals, the opening of a minicable and satellite master antenna TV market for TV receive-only systems, and business telecommunications earth terminals. Attention is also given to future directions regarding satellite positions, the concept of 'video-plus', and direct broadcast satellites.

Beakley, G. W.

1984-07-01

56

Cost Consideration for Future Communications Satellite  

NASA Astrophysics Data System (ADS)

This paper discusses the cost driving factors of the future communications satellite rather than discussing its cost itself directly, in terms of development period of time, services, and R&D by government. In the first, a period of time for development of a communications system is discussed in comparison of satellite communications system with a terrestrial communications system. Generally speaking, the terrestrial communications system is developed in a short period. Especially, the recent network related IT technology changes very rapidly, like so-called as "Dog Year". On the other hand, it takes a long time, more than several years, to develop a satellite communications system. This paper will discuss this time period of development is how to influence the system realization in various cases. In the second, the service related cost is discussed. First, a mobile communications satellite system is considered as an example. The tremendous penetration speed of the terrestrial cellular phones prevents from the success of the mobile satellite communications system. The success of the mobile satellite communications system depends on how early and user friendly to develop its user terminals. Second, the broadcasting service is described as a successful example. It is described that the satellite broadcasting has a very competitive advantage to the terrestrial broadcasting service from the cost point of view. Finally, the cost of the technology R&D for the future communication satellite by the government is discussed. A model of the future communications satellite for next 30 years has been proposed(1)(2). As an example, this paper estimates the satellite cost of the 60 Gbps range of capacity which is called as 1.5G satellite, where the capacity of the second generation Internet satellite (2G) is 50-500 Gbps per satellite. In the paper, the R&D plan of the future communications satellite will be discussed as a next R&D project to the first generation Internet satellite from a cost point of view. References (1)T.Iida and Y.Suzuki: "Satellite Communications R&D for Next 30 Years", 19th AIAA (2)T.Iida, Y.Suzuki and A.Akaishi: "Satellite Communications R&D for Next 30 Years:

Iida, Takashi

2002-01-01

57

AERONAUTICAL BROADBAND COMMUNICATIONS VIA SATELLITE  

Microsoft Academic Search

The paper discusses various aspects of aeronautical broadband satellite communications (AirCom). A range of applications and services is identified and categorized into the scenarios of in-flight entertainment, in-flight office, telemedicine, flight security, and flight logistics & maintenance. A number of operational and planned AirCom systems are presented. A structured overview of key issues and respective steps for the system design

M. Werner; M. Holzbock

58

Odyssey, an optimized personal communications satellite system  

NASA Astrophysics Data System (ADS)

Personal communications places severe demands on service providers and transmission facilities. Customers are not satisfied with the current levels of service and want improvements. Among the characteristics that users seek are: lower service rates, hand held convenience, acceptable time delays, ubiquitous service, high availability, reliability, and high quality. The space industry is developing commercial space systems for providing mobile communications to personal telephones. Provision of land mobile satellite service is fundamentally different from the fixed satellite service provided by geostationary satellites. In fixed service, the earth based antennas can depend on a clear path from user to satellite. Mobile users in a terrestrial environment commonly encounter blockage due to vegetation, terrain or buildings. Consequently, high elevation angles are of premium value. TRW studied the issues and concluded that a Medium Earth Orbit constellation is the best solution for Personal Communications Satellite Service. TRW has developed Odyssey, which uses twelve satellites in medium altitude orbit to provide personal communications satellite service. The Odyssey communications system projects a multibeam antenna pattern to the Earth. The attitude control system orients the satellites to ensure constant coverage of land mass and coastal areas. Pointing can be reprogrammed by ground control to ensure optimized coverage of the desired service areas. The payload architecture features non-processing, "bent pipe" transponders and matrix amplifiers to ensure dynamic power delivery to high demand areas. Circuit capacity is 3000 circuits per satellite. Each satellite weighs 1917 kg (4226 pounds) at launch and the solar arrays provide 3126 Watts of power. Satellites are launched in pairs on Ariane, Atlas, or other vehicles. Each satellite is placed in a circular orbit at an altitude of 10,354 km. There are three orbit planes inclined at 55° to the equatorial plane. Deployment of the satellites permits phased introduction of service. After only three launches, in which two satellites are launched into each plane, continuous service can be provided to most of the world. After three more launches for a total of 12 satellites, service can be expanded to all populated regions of the Earth with path diversity to most regions. The Odyssey system is superior to both geostationary satellites and low earth orbiting satellites. Odyssey provides many benefits to the end user which are described in the paper. These include: low cost, convenience, high availability, reliability, and acceptable time delay. Odyssey exhibits benefits for telecommunications operators: simple operations, incremental, phased startup, long space segment life-time, high profitability, dynamic flexibility for adjustment and short time to market. Since submission of an FCC application in 1991, TRW has continued to explore ways to further improve the Odyssey approach by expanding coverage to the entire world and reducing the initial investment while maintaining high quality service.

Rusch, Roger J.

59

Satellite communications system  

NASA Astrophysics Data System (ADS)

A satellite communication system is disclosed which provides an increased probability of reception by selective call receivers. In carrying out the invention in one form, there is provided a method comprising the step of relaying, from two or more locations via at least one satellite, a transmission to a receiver. By relaying the information being transmitted from two different locations (angles) at different points in time, the probability of reception is increased. Programming means are provided for determining the first and second locations and times of transmitting the information.

Schwendeman, Robert J.

1993-04-01

60

Land-mobile satellite communication system  

NASA Technical Reports Server (NTRS)

A satellite communications system includes an orbiting communications satellite for relaying communications to and from a plurality of ground stations, and a network management center for making connections via the satellite between the ground stations in response to connection requests received via the satellite from the ground stations, the network management center being configured to provide both open-end service and closed-end service. The network management center of one embodiment is configured to provides both types of service according to a predefined channel access protocol that enables the ground stations to request the type of service desired. The channel access protocol may be configured to adaptively allocate channels to open-end service and closed-end service according to changes in the traffic pattern and include a free-access tree algorithm that coordinates collision resolution among the ground stations.

Yan, Tsun-Yee (Inventor); Rafferty, William (Inventor); Dessouky, Khaled I. (Inventor); Wang, Charles C. (Inventor); Cheng, Unjeng (Inventor)

1993-01-01

61

Satellite Services Workshop, Volume 1  

NASA Technical Reports Server (NTRS)

Key issues associated with the orbital servicing of satellites are examined including servicing spacecraft and equipment, servicing operations, economics, satellite design, docking and berthing, and fluid management.

1982-01-01

62

Laser satellite communication network-vibration effect and possible solutions  

Microsoft Academic Search

A number of serious consortiums develop satellite communication networks. The objective of these communication projects is to service personal communication users almost everywhere on Earth. The intersatellite links in those projects use microwave radiation as the carrier. Free-space optical communication between satellites networked together can make possible high-speed communication between different places on Earth. Some advantages of an optical communication

SHLOMI ARNON; N. S. Kopeika

1997-01-01

63

Activities of Canadian Satellite Communications, Inc.  

NASA Astrophysics Data System (ADS)

Canadian Satellite Communications (Cancom) has as its core business the provision of television and radio signals to cable systems in Canada, with the objective of making affordable broadcast signals available to remote and/or small communities. Cancom also provides direct-to-home services to backyard receiving dishes, as well as satellite digital data business communications services, satellite business television, and satellite network services. Its business communication services range from satellite links for big-city businesses with small branch operations located far from major centers, to a mobile messaging and tracking system for the trucking industry. Revenues in 1992 totalled $48,212,000 and net income was just over $7 million. Cancom bought 10 percent interest in Leosat Corp. of Washington, DC, who are seeking approval to operate a position locator network from low-orbit satellites. Cancom has also become a partner in SovCan Star Satellite Communications Inc., which will build an international satellite system in partnership with Russia. The first satellite in this east-west business network will be placed in a Russian orbital slot over the Atlantic by 1996, and a second satellite will follow for the Pacific region. This annual report of Cancom's activities for 1992 includes financial statements and a six year financial review.

1992-12-01

64

The satellite communications alternative for maritime safety  

NASA Astrophysics Data System (ADS)

The current status of satellite communication technology for maritime users is surveyed, with an emphasis on emergency communication capabilities. Topics addressed include the organizational structure of Inmarsat, the present and planned Inmarsat space segment, the coastal and ship earth stations, the compact Standard-C terminal, the Enhanced Group Call system, and the L-band Satellite Emergency Position Indicating Radio Beacon. Consideration is given to the services available to Standard-C stations, distress and safety communication procedures, and the use of satellite communication to disseminate weather information. The equipment costs for various ship installations are indicated in a table.

Fear, James L.

1988-10-01

65

AUSSAT mobile satellite services  

NASA Technical Reports Server (NTRS)

An overview of AUSSAT's planned mobile satellite system is given. The development program which is being undertaken to achieve the 1992 service date is described. Both business and technical aspects of the development program are addressed.

Nowland, Wayne L.; Wagg, Michael; Simpson, Daniel

1988-01-01

66

Potential Use of the Australian Satellite Communications System for School of the Air and Enhanced Educational Services. Report Prepared for the Commonwealth/State Advisory Committee on the Educational Use of Communications Technology.  

ERIC Educational Resources Information Center

This report considers the potential for the use of the Australian Communications Satellite System (ACSS) for the Australian Schools of the Air (SOTAs) and the delivery of enhanced educational services, and develops the concept of all SOTAs operating through one transponder in a national beam. An evolutionary introduction of satellite transmission…

Davies, N. G.; Gillam, J. A.

67

Optical satellite communications in Europe  

NASA Astrophysics Data System (ADS)

This paper describes optical satellite communication activities based on technology developments, which started in Europe more than 30 years ago and led in 2001 to the world-first optical inter-satellite communication link experiment (SILEX). SILEX proved that optical communication technologies can be reliably mastered in space and in 2006 the Japanese Space Agency (JAXA) joined the optical inter-satellite experiment from their own satellite. Since 2008 the German Space Agency (DLR) is operating an inter-satellite link between the NFIRE and TerraSAR-X satellites based on a second generation of laser communication technology, which will be used for the new European Data Relay Satellite (EDRS) system to be deployed in 2013.

Sodnik, Zoran; Lutz, Hanspeter; Furch, Bernhard; Meyer, Rolf

2010-02-01

68

Advanced satellite communication system  

NASA Astrophysics Data System (ADS)

The objective of this research program was to develop an innovative advanced satellite receiver/demodulator utilizing surface acoustic wave (SAW) chirp transform processor and coherent BPSK demodulation. The algorithm of this SAW chirp Fourier transformer is of the Convolve - Multiply - Convolve (CMC) type, utilizing off-the-shelf reflective array compressor (RAC) chirp filters. This satellite receiver, if fully developed, was intended to be used as an on-board multichannel communications repeater. The Advanced Communications Receiver consists of four units: (1) CMC processor, (2) single sideband modulator, (3) demodulator, and (4) chirp waveform generator and individual channel processors. The input signal is composed of multiple user transmission frequencies operating independently from remotely located ground terminals. This signal is Fourier transformed by the CMC Processor into a unique time slot for each user frequency. The CMC processor is driven by a waveform generator through a single sideband (SSB) modulator. The output of the coherent demodulator is composed of positive and negative pulses, which are the envelopes of the chirp transform processor output. These pulses correspond to the data symbols. Following the demodulator, a logic circuit reconstructs the pulses into data, which are subsequently differentially decoded to form the transmitted data. The coherent demodulation and detection of BPSK signals derived from a CMC chirp transform processor were experimentally demonstrated and bit error rate (BER) testing was performed. To assess the feasibility of such advanced receiver, the results were compared with the theoretical analysis and plotted for an average BER as a function of signal-to-noise ratio. Another goal of this SBIR program was the development of a commercial product. The commercial product developed was an arbitrary waveform generator. The successful sales have begun with the delivery of the first arbitrary waveform generator.

Staples, Edward J.; Lie, Sen

1992-05-01

69

Advanced satellite communication system  

NASA Technical Reports Server (NTRS)

The objective of this research program was to develop an innovative advanced satellite receiver/demodulator utilizing surface acoustic wave (SAW) chirp transform processor and coherent BPSK demodulation. The algorithm of this SAW chirp Fourier transformer is of the Convolve - Multiply - Convolve (CMC) type, utilizing off-the-shelf reflective array compressor (RAC) chirp filters. This satellite receiver, if fully developed, was intended to be used as an on-board multichannel communications repeater. The Advanced Communications Receiver consists of four units: (1) CMC processor, (2) single sideband modulator, (3) demodulator, and (4) chirp waveform generator and individual channel processors. The input signal is composed of multiple user transmission frequencies operating independently from remotely located ground terminals. This signal is Fourier transformed by the CMC Processor into a unique time slot for each user frequency. The CMC processor is driven by a waveform generator through a single sideband (SSB) modulator. The output of the coherent demodulator is composed of positive and negative pulses, which are the envelopes of the chirp transform processor output. These pulses correspond to the data symbols. Following the demodulator, a logic circuit reconstructs the pulses into data, which are subsequently differentially decoded to form the transmitted data. The coherent demodulation and detection of BPSK signals derived from a CMC chirp transform processor were experimentally demonstrated and bit error rate (BER) testing was performed. To assess the feasibility of such advanced receiver, the results were compared with the theoretical analysis and plotted for an average BER as a function of signal-to-noise ratio. Another goal of this SBIR program was the development of a commercial product. The commercial product developed was an arbitrary waveform generator. The successful sales have begun with the delivery of the first arbitrary waveform generator.

Staples, Edward J.; Lie, Sen

1992-01-01

70

Survey: National Environmental Satellite Service  

NASA Technical Reports Server (NTRS)

The national Environmental Satellite Service (NESS) receives data at periodic intervals from satellites of the Synchronous Meteorological Satellite/Geostationary Operational Environmental Satellite series and from the Improved TIROS (Television Infrared Observational Satellite) Operational Satellite. Within the conterminous United States, direct readout and processed products are distributed to users over facsimile networks from a central processing and data distribution facility. In addition, the NESS Satellite Field Stations analyze, interpret, and distribute processed geostationary satellite products to regional weather service activities.

1977-01-01

71

Interim Service ISDN Satellite (ISIS) network model for advanced satellite designs and experiments  

NASA Technical Reports Server (NTRS)

The Interim Service Integrated Services Digital Network (ISDN) Satellite (ISIS) Network Model for Advanced Satellite Designs and Experiments describes a model suitable for discrete event simulations. A top-down model design uses the Advanced Communications Technology Satellite (ACTS) as its basis. The ISDN modeling abstractions are added to permit the determination and performance for the NASA Satellite Communications Research (SCAR) Program.

Pepin, Gerard R.; Hager, E. Paul

1991-01-01

72

New inclined synchronous satellite system for mobile communications and radiodetermination  

Microsoft Academic Search

A new satellite system using inclined synchronous satellites is proposed. This system can provide radiodetermination services as well as communication services for mobile earth stations in the common satellite system. In this system, two or more satellites can be always observed at the same time from any mobile terminal on the earth (including the polar regions) with an elevation angle

Fumiaki Sugaya; Yutaka Yasuda; Yasuo Hirata

1988-01-01

73

Encryption protection for communication satellites  

NASA Astrophysics Data System (ADS)

In connection with the growing importance of the commercial communication satellite systems and the introduction of new technological developments, users and operators of these systems become increasingly concerned with aspects of security. The user community is concerned with maintaining confidentiality and integrity of the information being transmitted over the satellite links, while the satellite operators are concerned about the safety of their assets in space. In response to these concerns, the commercial satellite operators are now taking steps to protect the communication information and the satellites. Thus, communication information is being protected by end-to-end encryption of the customer communication traffic. Attention is given to the selection of the NBS DES algorithm, the command protection systems, and the communication protection systems.

Sood, D. R.; Hoernig, O. W., Jr.

74

Trends in mobile satellite communication  

NASA Technical Reports Server (NTRS)

Ever since the U.S. Federal Communication Commission opened the discussion on spectrum usage for personal handheld communication, the community of satellite manufacturers has been searching for an economically viable and technically feasible satellite mobile communication system. Hughes Aircraft Company and others have joined in providing proposals for such systems, ranging from low to medium to geosynchronous orbits. These proposals make it clear that the trend in mobile satellite communication is toward more sophisticated satellites with a large number of spot beams and onboard processing, providing worldwide interconnectivity. Recent Hughes studies indicate that from a cost standpoint the geosynchronous satellite (GEOS) is most economical, followed by the medium earth orbit satellite (MEOS) and then by the low earth orbit satellite (LEOS). From a system performance standpoint, this evaluation may be in reverse order, depending on how the public will react to speech delay and collision. This paper discusses the trends and various mobile satellite constellations in satellite communication under investigation. It considers the effect of orbital altitude and modulation/multiple access on the link and spacecraft design.

Johannsen, Klaus G.; Bowles, Mike W.; Milliken, Samuel; Cherrette, Alan R.; Busche, Gregory C.

1993-01-01

75

Odyssey, an optimized personal communications satellite system  

NASA Astrophysics Data System (ADS)

Personal communications places severe demands on service providers and transmission facilities. Customers are not satisfied with the current levels of service and want improvements. Among the characteristics that users seek are: lower service rates, hand held convenience, acceptable time delays, ubiquitous service, high availability, reliability, and high quality. The space industry in developing commercial space systems for providing mobile communications to personal telephones. Provision of land mobile satellite service is fundamentally different from the fixed satellite service provided by geostationary satellites. In fixed service, the earth based antennas can depend on a clear path from user to satellite. Mobile users in a terrestrial environment commonly encounter blockage due to vegetation, terrain or buildings. Consequently, high elevation angles are of premium value. TRW studied the issues and concluded that a Medium Earth Orbit constellation is the best solution for Personal Communications Satellite Service. TRW has developed Odyssey, which uses twelve satellites in medium altitude orbit to provide personal communications satellite service. The Odyssey communications system projects a multibeam antenna pattern to the Earth. The attitude control system orients the satellites to ensure constant coverage of land mass and coastal areas. Pointing can be reprogrammed by ground control to ensure optimized coverage of the desired service areas. The payload architecture features non-processing, 'bent pipe' transponders and matrix amplifiers to ensure dynamic power delivery to high demand areas. Circuit capacity is 3000 circuits per satellite. Each satellite weighs 1917 kg (4226 pounds) at launch and the solar arrays provide 3126 watts of power. Satellites are launched in pairs on Ariane, Atlas, or other vehicles. Each satellite is placed in a circular orbit at an altitude of 10,354 km. satellites permits phased introduction of service. After only three launches, in which two satellites are launched into each plane, continuous service can be provided to most of the world. After three more launches for a total of 12 satellites, service can be expanded to all populated regions of the Earth with path diversity to most regions. *The Odyssey system is superior to both geostationary satellites and low earth orbiting satellites. -Odyssey provides many benefits to the end user which are described in the paper. These include: low cost, convenience, high availability, reliability, and acceptable time delay. Odyssey exhibits benefits for telecommunications operators: simple operations, incremental, phased startup, long space segment life-time, high profitability, dynamic flexibility for adjustment and short time to market. %Since submission of an FCC application in 1991, TRW has continued to explore ways to further improve the Odyssey approach by expanding coverage to the entire world and reducing the initial investment while maintaining high quality service.

Rusch, Roger J.

76

Antennas for mobile satellite communications  

NASA Astrophysics Data System (ADS)

A NASA sponsored program, called the Mobile Satellite (MSAT) system, has prompted the development of several innovative antennas at L-band frequencies. In the space segment of the MSAT system, an efficient, light weight, circularly polarized microstrip array that uses linearly polarized elements was developed as a multiple beam reflector feed system. In the ground segment, a low-cost, low-profile, and very efficient microstrip Yagi array was developed as a medium-gain mechanically steered vehicle antenna. Circularly shaped microstrip patches excited at higher-order modes were also developed as low-gain vehicle antennas. A more recent effort called for the development of a 20/30 GHz mobile terminal antenna for future-generation mobile satellite communications. To combat the high insertion loss encountered at 20/30 GHz, series-fed Monolithic Microwave Integrated Circuit (MMIC) microstrip array antennas are currently being developed. These MMIC arrays may lead to the development of several small but high-gain Ka-band antennas for the Personal Access Satellite Service planned for the 2000s.

Huang, John

1991-12-01

77

Antennas for mobile satellite communications  

NASA Technical Reports Server (NTRS)

A NASA sponsored program, called the Mobile Satellite (MSAT) system, has prompted the development of several innovative antennas at L-band frequencies. In the space segment of the MSAT system, an efficient, light weight, circularly polarized microstrip array that uses linearly polarized elements was developed as a multiple beam reflector feed system. In the ground segment, a low-cost, low-profile, and very efficient microstrip Yagi array was developed as a medium-gain mechanically steered vehicle antenna. Circularly shaped microstrip patches excited at higher-order modes were also developed as low-gain vehicle antennas. A more recent effort called for the development of a 20/30 GHz mobile terminal antenna for future-generation mobile satellite communications. To combat the high insertion loss encountered at 20/30 GHz, series-fed Monolithic Microwave Integrated Circuit (MMIC) microstrip array antennas are currently being developed. These MMIC arrays may lead to the development of several small but high-gain Ka-band antennas for the Personal Access Satellite Service planned for the 2000s.

Huang, John

1991-01-01

78

Mobile satellite service in the United States  

NASA Astrophysics Data System (ADS)

Mobile satellite service (MSS) has been under development in the United States for more than two decades. The service will soon be provided on a commercial basis by a consortium of eight U.S. companies called the American Mobile Satellite Consortium (AMSC). AMSC will build a three-satellite MSS system that will offer superior performance, reliability and cost effectiveness for organizations requiring mobile communications across the U.S. The development and operation of MSS in North America is being coordinated with Telesat Canada and Mexico. AMSC expects NASA to provide launch services in exchange for capacity on the first AMSC satellite for MSAT-X activities and for government demonstrations.

Agnew, Carson E.; Bhagat, Jai; Hopper, Edwin A.; Kiesling, John D.; Exner, Michael L.; Melillo, Lawrence; Noreen, Gary K.; Parrott, Billy J.

1988-05-01

79

Mobile satellite service in the United States  

NASA Technical Reports Server (NTRS)

Mobile satellite service (MSS) has been under development in the United States for more than two decades. The service will soon be provided on a commercial basis by a consortium of eight U.S. companies called the American Mobile Satellite Consortium (AMSC). AMSC will build a three-satellite MSS system that will offer superior performance, reliability and cost effectiveness for organizations requiring mobile communications across the U.S. The development and operation of MSS in North America is being coordinated with Telesat Canada and Mexico. AMSC expects NASA to provide launch services in exchange for capacity on the first AMSC satellite for MSAT-X activities and for government demonstrations.

Agnew, Carson E.; Bhagat, Jai; Hopper, Edwin A.; Kiesling, John D.; Exner, Michael L.; Melillo, Lawrence; Noreen, Gary K.; Parrott, Billy J.

1988-01-01

80

Satellite communication from user to user  

NASA Astrophysics Data System (ADS)

Satellite communication systems which allow a multitude of user-to-user, point-to-point, and multipoint connections, are presented. The bit rates are 64 kbit/sec and multiples, up to 1.92 Mbit/sec. If required, the ground-stations are installed at the customer's site or at suitable locations in order to serve several customers. However, technical requirements for station location have also to be fulfulled, in order to avoid interference with terrestrial radio services. The increasing number of participants to Satellite Multi Service and INTELSAT Business Services imposes the solution of the problem of communication using cheap techniques. The changes of the German Federal Post Office also permit the economic use of satellite radio techniques for short distances.

Gern, Manfred

81

Modulation and coding used by a major satellite communications company  

NASA Technical Reports Server (NTRS)

Hughes Communications Inc., is a major satellite communications company providing or planning to provide the full spectrum of services available on satellites. All of the current services use conventional modulation and coding techniques that were well known a decade or longer ago. However, the future mobile satellite service will use significantly more advanced techniques. JPL, under NASA sponsorship, has pioneered many of the techniques that will be used.

Renshaw, K. H.

1992-01-01

82

Navy satellite communications systems in transition  

NASA Astrophysics Data System (ADS)

Navy SATCOM programs require advanced system engineering, program management, and long range planning to improve satellite and ground system technology. Solutions are being sought to develop Navy transitional issues within the framework of the total Defense MILSATCOM architecture. Several of the Navy SATCOM transition issues are discussed: the current Navy SATCOM baseline, consisting of three GAPFILLER (MARISAT) satellites and a constellation of geosynchronous FLTSATCOM satellites; a Demand Assignment time-division Multiple Access (DAMA) system, which permits a more efficient use of the 25 kHz FLTSAT hard-limiting transponders. A leased satellite (LEASAT) will provide extended UHF SATCOM service at four geosynchronous orbital locations. The navy also plans to increase connectivity, capacity, and AJ protection of Fleet Satellite Communications by introduction of SHF service.

Newell, J. W.

83

Broadband satellite communication ... -Google Livros Descrio geral  

E-print Network

Broadband satellite communication ... - Google Livros Descrição geral > Pré-visualização Críticas (0) Comprar (0) - Escrever crítica Adicionar à minha biblioteca Obter este livro Springer Amazon » Livros relacionados Todos os livros relacionados » Links Patrocinados Global Teleport Services

Monteiro, Edmundo

84

Delivery of satellite based broadband services  

NASA Astrophysics Data System (ADS)

Availability of speedy communication links to individuals and organizations is essential to keep pace with the business and social requirements of this modern age. While the PCs have been continuously growing in processing speed and memory capabilities, the availability of broadband communication links still has not been satisfactory in many parts of the world. Recognizing the need to give fillip to the growth of broadband services and improve the broadband penetration, the telecom policies of different counties have placed special emphasis on the same. While emphasis is on the use of fiber optic and copper in local loop, satellite communications systems will play an important role in quickly establishing these services in areas where fiber and other communication systems are not available and are not likely to be available for a long time to come. To make satellite communication systems attractive for the wide spread of these services in a cost effective way special emphasis has to be given on factors affecting the cost of the bandwidth and the equipment. As broadband services are bandwidth demanding, use of bandwidth efficient modulation technique and suitable system architecture are some of the important aspects that need to be examined. Further there is a need to re-look on how information services are provided keeping in view the user requirements and broadcast capability of satellite systems over wide areas. This paper addresses some of the aspects of delivering broadband services via satellite taking Indian requirement as an example.

Chandrasekhar, M. G.; Venugopal, D.

2007-06-01

85

Communications and media services  

NASA Technical Reports Server (NTRS)

NASA's internal and external communication methods are reviewed. NASA information services for the media, for the public, and for employees are discussed. Consideration is given to electron information distribution, the NASA TV-audio system, the NASA broadcast news service, astronaut appearances, technology and information exhibits, speaker services, and NASA news reports for internal communications. Also, the NASA worldwide electronic mail network is described and trends for future NASA communications and media services are outlined.

Mcculla, James W.; Kukowski, James F.

1990-01-01

86

Gigabit Satellite Network for NASA's Advanced Communication Technology Satellite (ACTS)  

NASA Technical Reports Server (NTRS)

The advanced communication technology satellite (ACTS) gigabit satellite network provides long-haul point-to-point and point-to-multipoint full-duplex SONET services over NASA's ACTS. at rates up to 622 Mbit/s (SONET OC-12), with signal quality comparable to that obtained with terrestrial fiber networks. Data multiplexing over the satellite is accomplished using time-division multiple access (TDMA) techniques coordinated with the switching and beam hopping facilities provided by ACTS. Transmissions through the satellite are protected with Reed-Solomon encoding. providing virtually error-free transmission under most weather conditions. Unique to the system are a TDMA frame structure and satellite synchronization mechanism that allow: (a) very efficient utilization of the satellite capacity: (b) over-the-satellite dosed-loop synchronization of the network in configurations with up to 64 ground stations: and (c) ground station initial acquisition without collisions with existing signalling or data traffic. The user interfaces are compatible with SONET standards, performing the function of conventional SONET multiplexers and. as such. can be: readily integrated with standard SONET fiber-based terrestrial networks. Management of the network is based upon the simple network management protocol (SNMP). and includes an over-the-satellite signalling network and backup terrestrial internet (IP-based) connectivity. A description of the ground stations is also included.

Hoder, Douglas; Bergamo, Marcos

1996-01-01

87

Telemammography Using Satellite Communications  

NASA Technical Reports Server (NTRS)

Telemammography, the electronic transmission of digitized mammograms, can connect patients with timely, critical medical expertise; howev er, an adequate terrestrial communications infrastructure does not exist in these areas. NASA Lewis Research Center's Advanced Space Commu nications Laboratory is now working with leading breast cancer resear ch hospitals, including the Cleveland Clinic and the University of Virginia, to perform the critical research necessary to allow new satell ite networks to support telemammography.

1996-01-01

88

Managing a satellite communications program in a hospital library.  

PubMed Central

A satellite communications service used for the continuing education of hospital staff can be successfully managed by a hospital library. Organization of the service includes managing equipment and personnel, finding programming, marketing the service, arranging for teleconferences, and establishing videotape procedures. A satellite communications program gives the library the opportunity to establish new partnerships with other departments in the hospital as well as with other segments of the community. PMID:3594024

Sutton, L S; Phillips, F M; Winfield, S R

1987-01-01

89

Coding for reliable satellite communications  

NASA Technical Reports Server (NTRS)

Several error control coding techniques for reliable satellite communications were investigated to find algorithms for fast decoding of Reed-Solomon codes in terms of dual basis. The decoding of the (255,223) Reed-Solomon code, which is used as the outer code in the concatenated TDRSS decoder, was of particular concern.

Lin, S.

1984-01-01

90

Communications satellite systems operations with the space station, volume 2  

NASA Technical Reports Server (NTRS)

A financial model was developed which described quantitatively the economics of the space segment of communication satellite systems. The model describes the economics of the space system throughout the lifetime of the satellite. The expected state-of-the-art status of communications satellite systems and operations beginning service in 1995 were assessed and described. New or enhanced space-based activities and associated satellite system designs that have the potential to achieve future communications satellite operations in geostationary orbit with improved economic performance were postulated and defined. Three scenarios using combinations of space-based activities were analyzed: a spin stabilized satellite, a three axis satellite, and assembly at the Space Station and GEO servicing. Functional and technical requirements placed on the Space Station by the scenarios were detailed. Requirements on the satellite were also listed.

Price, K.; Dixon, J.; Weyandt, C.

1987-01-01

91

Satellite Servicing Technology Development Missions  

NASA Technical Reports Server (NTRS)

A new capability regarding the U.S. space efforts will be related to the servicing of satellites in orbit utilizing first-generation space station as the collection point or base for Shuttle-delivered payloads. Orbital maneuvering vehicles could move payloads or spacecraft assembled at the Shuttle/space station terminus to other earth orbit locations. It is assumed that such a capability will be initially available in the early 1990's. The benefits provided by satellite servicing in orbit are discussed, taking into account extended satellite lifetimes, lower acquisition cost, improved satellite performance, the possibility to change a satellite's mission, optimized science, and higher satellite reliability. The requirements for Satellite Servicing Technology Development Missions (TDMs) are considered. It is found that existing technology is insufficient, in various areas, to perform the servicing operations. A list is provided of critical technologies which must be developed.

Middleton, R.; Waltz, D.; Schrock, S.

1984-01-01

92

Customer concerns regarding satellite servicing  

NASA Technical Reports Server (NTRS)

The organization of orbital servicing of satellites is discussed. Provision of servicing equipment; design interfaces between the satellite and the servicing equipment; and the economic viability of the concept are discussed. The proposed solution for satisfying customer concerns is for the servicing organizations to baseline an adequate inventory of servicing equipment with standard interfaces and established servicing costs. With this knowledge, the customer can conduct tradeoff studies and make programmatic decisions regarding servicing options. A dialog procedure between customers and servicing specialists is outlined.

Rysavy, Gordon

1987-01-01

93

Satellite communication - A review of experiences and possibilities  

Microsoft Academic Search

The scope of a multinational conference is presented regarding satellite communication. Specific attention is given to available satellite service, development and planning strategies, new applications for satellite networks, and technological growth in both space- and land-based systems. The use of leased transponders, digitalization, and different signal treatment systems are considered, and the problems associated with the 11-14 GHz range are

Francisco Gomez Alamillo

1990-01-01

94

Mobile satellite service for Canada  

NASA Technical Reports Server (NTRS)

The Mobile Satellite (MSAT) system and a special program designed to provide interim mobile satellite services (IMSS) during the construction phase of MSAT are described. A mobile satellite system is a key element in extending voice and and data telecommunications to all Canadians.

Sward, David

1988-01-01

95

Research Supporting Satellite Communications Technology  

NASA Technical Reports Server (NTRS)

This report describes the second year of research effort under the grant Research Supporting Satellite Communications Technology. The research program consists of two major projects: Fault Tolerant Link Establishment and the design of an Auto-Configurable Receiver. The Fault Tolerant Link Establishment protocol is being developed to assist the designers of satellite clusters to manage the inter-satellite communications. During this second year, the basic protocol design was validated with an extensive testing program. After this testing was completed, a channel error model was added to the protocol to permit the effects of channel errors to be measured. This error generation was used to test the effects of channel errors on Heartbeat and Token message passing. The C-language source code for the protocol modules was delivered to Goddard Space Flight Center for integration with the GSFC testbed. The need for a receiver autoconfiguration capability arises when a satellite-to-ground transmission is interrupted due to an unexpected event, the satellite transponder may reset to an unknown state and begin transmitting in a new mode. During Year 2, we completed testing of these algorithms when noise-induced bit errors were introduced. We also developed and tested an algorithm for estimating the data rate, assuming an NRZ-formatted signal corrupted with additive white Gaussian noise, and we took initial steps in integrating both algorithms into the SDR test bed at GSFC.

Horan Stephen; Lyman, Raphael

2005-01-01

96

Trends in NASA communication satellites  

NASA Technical Reports Server (NTRS)

Satellite telecommunications can help to satisfy several national needs such as education, health care, cultural opportunities, and data transfer. There are current experiments being conducted with NASA spacecraft ATS 1, 3, and 5 in an attempt to satisfy these national needs. Future experiments are planned for the ATS F/G and CTS spacecrafts. The next generation of communications satellites must provide multiple region coverage, multichannel capability, high quality TV pictures, and must allow low cost ground receivers to be used. The proposed NASA spacecrafts, ATS H/I, will satisfy these requirements. Other countries of the world can benefit from ATS H/I technology.

Sivo, J. N.; Robbins, W. H.; Stretchberry, D. M.

1972-01-01

97

Full Service ISDN Satellite (FSIS) network model for advanced ISDN satellite design and experiments  

NASA Technical Reports Server (NTRS)

The Full Service Integrated Services Digital Network (FSIS) network model for advanced satellite designs describes a model suitable for discrete event simulations. A top down model design uses the Advanced Communications Technology Satellite (ACTS) as its basis. The ACTS and the Interim Service ISDN Satellite (ISIS) perform ISDN protocol analyses and switching decisions in the terrestrial domain, whereas FSIS makes all its analyses and decisions on-board the ISDN satellite.

Pepin, Gerard R.

1992-01-01

98

Satellite-Based Quantum Communications  

Microsoft Academic Search

Single-photon quantum communications (QC) offers the attractive feature of 'future proof', forward security rooted in the laws of quantum physics. Ground based quantum key distribution (QKD) experiments in optical fiber have attained transmission ranges in excess of 200km, but for larger distances we proposed a methodology for satellite-based QC. Over the past decade we have devised solutions to the technical

Richard J Hughes; Jane E Nordholt; Kevin P Mc Cabe; Raymond T Newell; Charles G Pterson

2010-01-01

99

Advanced mobile satellite communications using COMETS satellite in MM-wave and Ka-band  

NASA Technical Reports Server (NTRS)

Early in the 21st century, the demand for personal communications using mobile, hand-held, and VSAT terminals will rapidly increase. In a future system, many different types of services should be provided with one-hop connection. The Communications Research Laboratory (CRL) has studied a future advanced mobile satellite communications system using millimeter wave and Ka band. In 1990, CRL started the Communications and Broadcasting Engineering Test Satellite (COMETS) project. The satellite has been developed in conjunction with NASDA and will be launched in 1997. This paper describes the COMETS payload configuration and the experimental system for the advanced mobile communications mission.

Ohmori, Shingo; Isobe, Shunkichi; Takeuchi, Makoto; Naito, Hideyuki

1993-01-01

100

Satellite-Based Quantum Communications  

SciTech Connect

Single-photon quantum communications (QC) offers the attractive feature of 'future proof', forward security rooted in the laws of quantum physics. Ground based quantum key distribution (QKD) experiments in optical fiber have attained transmission ranges in excess of 200km, but for larger distances we proposed a methodology for satellite-based QC. Over the past decade we have devised solutions to the technical challenges to satellite-to-ground QC, and we now have a clear concept for how space-based QC could be performed and potentially utilized within a trusted QKD network architecture. Functioning as a trusted QKD node, a QC satellite ('QC-sat') could deliver secret keys to the key stores of ground-based trusted QKD network nodes, to each of which multiple users are connected by optical fiber or free-space QC. A QC-sat could thereby extend quantum-secured connectivity to geographically disjoint domains, separated by continental or inter-continental distances. In this paper we describe our system concept that makes QC feasible with low-earth orbit (LEO) QC-sats (200-km-2,000-km altitude orbits), and the results of link modeling of expected performance. Using the architecture that we have developed, LEO satellite-to-ground QKD will be feasible with secret bit yields of several hundred 256-bit AES keys per contact. With multiple ground sites separated by {approx} 100km, mitigation of cloudiness over any single ground site would be possible, potentially allowing multiple contact opportunities each day. The essential next step is an experimental QC-sat. A number of LEO-platforms would be suitable, ranging from a dedicated, three-axis stabilized small satellite, to a secondary experiment on an imaging satellite. to the ISS. With one or more QC-sats, low-latency quantum-secured communications could then be provided to ground-based users on a global scale. Air-to-ground QC would also be possible.

Hughes, Richard J [Los Alamos National Laboratory; Nordholt, Jane E [Los Alamos National Laboratory; Mc Cabe, Kevin P [Los Alamos National Laboratory; Newell, Raymond T [Los Alamos National Laboratory; Pterson, Charles G [Los Alamos National Laboratory

2010-09-20

101

Satellite communications systems and technology. Volume 1; Analytic Chapters  

NASA Technical Reports Server (NTRS)

Volume 1 (Analytical Chapters) of the final report of the NASA/NSF Panel Satellite Communications Systems and Technology is presented. The panel surveyed advanced technology being developed for commercial use in the satellite communications field in Europe, Japan, and Russia. All aspects of satellite communications were considered, including fixed, broadcast, mobile, personal communications, navigation, low earth orbit, and small satellites. The focus of the study was on experimental and advanced technology being developed in R&D and demonstration programs rather than on today's production capabilities. The report focuses on commercial satellite technology, and does not review defense-related or other confidential satellite communications capabilities. The NASA/NSF panel concluded that the United States has lost its leading position in many critical satellite communications technologies. Although U.S. industry retains a leading position in today's marketplace for satellite communications systems and services, this position is largely founded on technologies and capabilities developed in the 1960s and 1970s. Because the United States is losing ground with respect to a wide range of technologies and systems that will be key to future communications markets, the market share of the U.S. satellite communications industry is at risk.

Jennings, Raymond D.; Mahle, Christoph E.; Miller, Edward F.; Riley, Lance; Pelton, Joseph N.; Bostian, Charles W.; Brandon, William T.; Chan, Vincent W. S.; Hager, E. Paul; Edelson, Burton I.; Kwan, Robert K.; Helm, Neil R.

1993-01-01

102

Satellite communications systems and technology. Volume 1: Analytical chapters  

NASA Technical Reports Server (NTRS)

This is Volume 1 (Analytical Chapters) of the final report of the NASA/NSF Panel Satellite Communications Systems and Technology. The panel surveyed advanced technology being developed for commercial use in the satellite communications field in Europe, Japan, and Russia. All aspects of satellite communications were considered, including fixed, broadcast, mobile, personal communications, navigation, low earth orbit, and small satellites. The focus was on experimental and advanced technology being developed in R&D and demonstration programs rather than on today's production capabilities. Focus was on commercial satellite technology, and does not review defense-related or other confidential satellite communications capabilities. The NASA/NSF panel concluded that the United States has lost its leading position in many critical satellite communications technologies. Although U.S. industry retains a leading position in today's marketplace for satellite communications systems and services, this position is largely founded on technologies and capabilities developed in the 1960's and 1970's. Because the United States is losing ground with respect to a wide range of technologies and systems that will be key to future communications markets, the market share of the U.S. satellite communications industry is at risk.

Edelson, Burton I. (editor); Pelton, Joseph N. (editor); Bostian, Charles W.; Brandon, William T.; Chan, Vincent W. S.; Hager, E. Paul; Helm, Neil R.; Jennings, Raymond D.; Kwan, Robert K.; Mahle, Christoph E.

1993-01-01

103

Protocol Design for Mobile Radio Group Communications Over Satellite  

Microsoft Academic Search

A protocol design for a mobile radio service supporting half-duplex push-to-talk voice communications over mobile satellite systems is presented. The service enables a closed group of mobile radio users to communicate among themselves, so that a transmission from any user is received by all. A key issue is the efficient utilization of satellite channels. Demand-assignment multiple access (DAMA) is employed

Victor C. M. Leung

1992-01-01

104

Application of the Iridium Satellite System to Aeronautical Communications  

NASA Technical Reports Server (NTRS)

The next generation air transportation system will require greater air-ground communications capacity to accommodate more air traffic with increased safety and efficiency. Communications will remain primarily terrestrially based, but satellite communications will have an increased role. Inmarsat s aeronautical services have been approved and are in use for aeronautical safety communications provided by geostationary satellites. More recently the approval process for the Iridium low earth orbit constellation is nearing completion. The current Iridium system will be able to provide basic air traffic services communications suitable for oceanic, remote and polar regions. The planned second generation of the Iridium system, called Iridium NEXT, will provide enhanced capabilities and enable a greater role in the future of aeronautical communications. This paper will review the potential role of satellite communications in the future of air transportation, the Iridium approval process and relevant system testing, and the potential role of Iridium NEXT.

Kerczewski, Robert J.; Meza, Mike; Gupta, Om

2008-01-01

105

A review of mobile satellite communication systems  

NASA Astrophysics Data System (ADS)

This article describes mobile satellite systems in the planning or development stage such as MSAT, AMSC and Geostar and mobile satellite communication experiments such as PRODAT. Studies on the system such as T-SAT are also reviewed. In addition, Japanese ETS-V and ETS-VI are described. The development of mobile-satellite communication systems is promoted along with those of communication and satellite technologies.

Kondo, Kimio

1990-03-01

106

The Impact of Satellites on Cable Communications.  

ERIC Educational Resources Information Center

Two recent developments in communications satellite technology may speed the coming of cable TV (CATV) networks. First, increases in satellite power are reducing the cost of ground stations. Second, a connection between one ground station, the satellite, and any other ground station is no longer necessarily fixed. Now one station can communicate

Chayes, Abram

107

Ground-to-satellite laser communication experiments  

Microsoft Academic Search

Ground-to-satellite laser communication experiments between the optical ground station located in Koganei, central Tokyo, and a low earth orbit (LEO) satellite were jointly performed by the Japan Aerospace Exploration Agency and the National Institute of Information and Communications Technology. In 18 trials during three non-consecutive months, the satellite was acquired and tracked 61 % of the time, when clear or

Monio Toyoshima; Yoshihisa Takayama; Takashi Takahashi; Kenji Suzuki; Shinichi Kimura; Kenichi Takizawa; Tosbiaki Kuri; Werner Klaus; Masahiro Toyoda; Hiroo Kunimori; Takashi Jono; Katsuyoshi Arai

2008-01-01

108

Satellite communications and broadcasting; Proceedings of the International Conference, London, England, Dec. 2-4, 1986  

NASA Astrophysics Data System (ADS)

Papers are presented on private satellite networks in the U.S.; the competitive market for international satellite services; private satellite networks in Europe; and various applications for satellites, in particular data broadcasting and business communications. Topics discussed include the worldwide regulation of satellite broadcasting and communications; the capabilities of Eutelsat II; trends in satellite technology; and the role of insurance in space industries. Consideration is given to the use of the ASTRA satellite for TV broadcasting; the services provided by Intelsat; the evolution of American television due to satellites; consumer satellite Television Receive Only marketing in Europe; and satellite programming.

109

Domestic satellite communications - The Canadian experience  

NASA Astrophysics Data System (ADS)

The history of commercial satellite communications in Canada is surveyed. The benefits provided by the existing system are illustrated by focusing on the experience of a particular Arctic hamlet (Pangnirtung). Attention is given to the factors that have differentiated the Canadian system from the American one (smaller, less homogenous, and more widely dispersed population). The problem posed by 'pirate' earth stations in Canada is discussed. An account is given of the origin of the dual-band Anik B (6/4 GHz and 14/12 GHz channels) satellite series, and the experiments (telemedicine, tele-education, communication with remote communities) carried out with the Anik B are discussed. Attention is also given to the promising results obtained in the direct-to-home TV service delivered by Anik B. Plans for the Anik C (16 channels 14/12 GHz frequency band) and Anik D (24 channels 6/4 GHz frequency band) series are discussed. Canada's communications needs are such that the continued development of satellite systems seems assured.

Golden, D. A.

1980-09-01

110

Communication by Polar-Orbit Satellite Relay  

Microsoft Academic Search

Aircraft on transpolar flights do not have highly reliable noise-free communications. By the use of polar-orbiting satellite repeaters, UHF communications can be utilized. Active, wideband repeaters are proposed in the satellite, using equipment similar to existing hardware. A system is discussed for a 5000-mile altitude satellite orbit and a 3500-mile ground distance separation. Complete system parameters are described. The satellite

W. Hagan

1960-01-01

111

Experiments on aeronautical satellite communications using ETS-V satellite  

Microsoft Academic Search

The world's first aeronautical satellite communication experiments, conducted at L-band frequencies using a commercial aircraft, are described. An airborne antenna with electronically steerable beam and communication equipment was installed in a B-747F freighter flying over transoceanic flight routes. The satellite used in these experiments is the Engineering Test Satellite-Five (ETS-V). During the test period, various experiments, such as antenna pattern

S. Ohmori; Y. Hase; H. Wakana; S. Taira

1992-01-01

112

An optimization model of communications satellite planning  

NASA Astrophysics Data System (ADS)

A mathematical planning model is developed to help make cost effective decisions on key physical and operational parameters, for a satellite intended to provide customer premises services (CPS). The major characteristics of the model are: (1) interactions and tradeoffs among technical variables are formally captured; (2) values for capacity and operational parameters are obtained through optimization, greatly reducing the need for heuristic choices of parameter values; (3) effects of physical and regulatory constraints are included; and (4) the effects of market prices for transmission capacity on planning variables are explicitly captured. The model is solved optimally using geometric programming methods. Sensitivity analysis yields coefficients, analogous to shadow prices, that quantitatively indicate the change in objective function value resulting from variations in input parameter values. This helps in determining the robustness of planning decisions and in coping with some of the uncertainty that exists at the planning stage. The model can therefore be useful in making economically viable planning decisions for communications satellites.

Dutta, Amitava; Rama, Dasaratha V.

1992-09-01

113

Packet radio in the amateur satellite service  

Microsoft Academic Search

A review of the satellite-based packet radio activities taking place in the Amateur Radio Service is presented. Five projects are discussed. The Digital Communications Experiment (DCE) on Uosat OSCAR-11 is a store-and-forward system that is accessed by a limited number of stations around the world designated as DCE gateways. These gateway stations retrieve and store messages forwarded to them via

Robert J. Diersing; Jeffrey W. Ward

1989-01-01

114

Packet radio in the Amateur Satellite Service  

Microsoft Academic Search

A review of the satellite-based packet radio activities taking place in the Amateur Radio Service is presented. Five projects are discussed. The Digital Communications Experiment (DCE) on UoSAT-OSCAR-11 is a store-and-forward system that is accessed by a limited number of stations around the world designated as DCE gateways. These gateway stations retrieve and store messages forwarded to them via terrestrial

ROBERT J. DIERSING; JEFFREY W. WARD

1989-01-01

115

Phased arrays for communications satellites  

NASA Astrophysics Data System (ADS)

This paper describes a design approach for frequency-reuse communications satellites that use multibeam array antennas. The multibeam antenna is able to cover all or part of the earth's surface with contiguous independent circularly polarized beam spots, with overlap to minimize loss of gain between spots. The transmitting and receiving antennas are active space-fed planar arrays which use wide bandwidth elements and real time delay lines for beam formulation. The array is not phase scanned; it is a fixed, space-fed, active constrained lens. The term 'active' means that RF power amplifiers are distributed in the main aperture of the transmitting antenna, and RF pre-amplifiers are distributed in the main aperture of the receiving antenna. Multiple circularly polarized beams are produced by multiple independent antenna feeds. Good polarization isolation and low sidelobes allow a high degree of frequency reuse.

Schultz, J.

116

Satellite services system analysis study. Volume 2: Satellite and services user model  

NASA Technical Reports Server (NTRS)

Satellite services needs are analyzed. Topics include methodology: a satellite user model; representative servicing scenarios; potential service needs; manned, remote, and automated involvement; and inactive satellites/debris. Satellite and services user model development is considered. Groundrules and assumptions, servicing, events, and sensitivity analysis are included. Selection of references satellites is also discussed.

1981-01-01

117

A practical system for regional mobile satellite services  

NASA Technical Reports Server (NTRS)

The Regional Mobile Satellite (MSAT) concept proposes a worldwide, interconnected mobile satellite service (MSS) network in which MSAT-type satellites provide the space segment services to separate regions (i.e., one or a few countries). Using this concept, mobile communications users across entire continents can now be served by a handful of regionally controlled satellites in geostationary earth orbit (GEO). All requirements, including hand-held telephone capabilities, can be cost-effectively provided using proven technologies. While other concepts of regional or global mobile communications continue to be explored, the Hughes Regional MSAT system demonstrates the near-term viability of the GEO approach.

Glein, Randall; Leverson, Denis; Olmstead, Dean

1993-01-01

118

Communications satellite system for Africa  

NASA Astrophysics Data System (ADS)

Earlier established requirement estimations were improved upon by contacting African administrations and organizations. An enormous demand is shown to exist for telephony and teletype services in rural areas. It is shown that educational television broadcasting should be realized in the current African transport and communications decade (1978-1987). Radio broadcasting is proposed in order to overcome illiteracy and to improve educational levels. The technical and commercial feasibility of the system is provided by computer simulations which demonstrate how the required objectives can be fulfilled in conjunction with ground networks.

Kriegl, W.; Laufenberg, W.

1980-09-01

119

INMARSAT SATELLITE DATA COMMUNICATION CHANNEL SIMULATOR  

Microsoft Academic Search

This paper describes Inmarsat Satellite data communication infrastructure for a simulator. This communication channel implements GMDSS (Global Maritime Distress and Safety System) and data transfer functions between INMARSAT-C compatible terminal and a Land Earth Station (LES). Thrane & Thrane compatible software, installed on embedded controller is used for simulation of Inmarsat terminal. This controller transfer data to simulated Inmarsat satellite

Sorin-Robertino Sintea

120

Dimensioning of Aeronautical Satellite Services  

NASA Astrophysics Data System (ADS)

This paper will provide a generalised baseline for a systematic AirCom design process and address in particular the dimensioning of satellite systems for aeronautical services. These services will roll out soon in medium- and long-haul aircraft. The offered services will range from low rate telephony, internet access, and streaming applications for video and audio. The aggregate bit rates on up- and downlink will certainly be statistically time-dependent and asymmetric in forward and backward direction. A tool will be described that is able to model this traffic. Furthermore the dimensioning of satellite constellations can be done. Due to the stochastic nature of the traffic, multi-service models for the traffic generation of different services will be described. Furthermore, the traffic will be affected by the available bit rate and shaping or blocking will equalize the peak loads. If fleets with many aircraft are considered, aeronautical traffic models must be based on actual aircraft routes, flight schedules, location and time of day, as well as seats per aircraft and type of aircraft (charter, business etc.). The regionally distributed traffic has to be served by several satellites and appropriate sharing of the serving satellites may spread the traffic in hot zones and yield a better load distribution. When aeronautical services will spread out, the capacity demand will grow quickly and the capacity of existing Ku-band GEO satellites will soon be exceeded. Changing to higher frequency bands will provide large spectrum portions and smaller spotbeams will allow better frequency reuse. Even constellations with non-geostationary satellites could be re-advent to serve better the higher latitude regions. Then, another mobility component for the fast changing satellite topology need to be addressed, and routing issues of the traffic must be considered. The paper will describe solutions for the mapping of satellites and traffic demand as well as routing algorithms. Numerical values will show the capabilities of the developed tool by calculating the performance of some selected scenarios. The paper will also address wireless cabin services (cell phones and W-LAN access for laptops) of the WirelessCabin project.

Holzbock, M.; Jahn, A.; Werner, M.

2002-01-01

121

NASA compendium of satellite communications programs  

NASA Technical Reports Server (NTRS)

A comprehensive review is given of worldwide satellite communication programs that range in time from the inception of satellite communications to mid-1974. Particular emphasis is placed on program results, including experiments conducted, communications system operational performance, and technology employed. The background for understanding these results is established through brief summaries of the program organization, system configuration, and satellite and ground terminal characteristics. Major consideration is given to the communications system aspects of each program, but general spacecraft technology and other experiments conducted as part of the same program are mentioned summarily.

1975-01-01

122

Satellite services handbook. Interface guidelines  

NASA Technical Reports Server (NTRS)

Satellite interfaces for on orbit servicing, both manned and unmanned are identified, and is intended to be used by designers of space vehicles, both foreign and domestic. A primary concern is for design of interfaces with the astronaut in the loop, especially extravehicular activity, but also intravehicular activity and operations that are remote but have man-in-the-loop. The main emphasis is on servicing in low earth orbits from the Space Shuttle and also from the Space Station or other platforms.

1983-01-01

123

Estimating Rain Attenuation In Satellite Communication Links  

NASA Technical Reports Server (NTRS)

Attenuation computed with help of statistical model and meteorological data. NASA Lewis Research Center Satellite Link Attenuation Model (SLAM) program QuickBASIC computer program evaluating static and dynamic statistical assessment of impact of rain attenuation on communication link established between Earth terminal and geosynchronous satellite. Application in specification, design, and assessment of satellite communication links for any terminal location in continental United States. Written in Microsoft QuickBASIC.

Manning, R. M.

1991-01-01

124

Prediction of fading phenomena in land-satellite communication links  

Microsoft Academic Search

This paper addresses the problem of prediction of probability of successful radio communication of any mobile or stationary subscriber located in areas of service such as complex urban environments characterized by nonline-of-sight propagation conditions, which limit GPS, Low Earth Orbit, and Medium Earth Orbit services in land-satellite communications. It presents a self-consistent physical-statistical approach for predicting fading phenomena usually occurring

N. Blaunstein; Y. Cohen; M. Hayakawa

2010-01-01

125

Space industrialization - Education. [via communication satellites  

NASA Technical Reports Server (NTRS)

The components of an educational system based on, and perhaps enhanced by, space industrialization communications technology are considered. Satellite technology has introduced a synoptic distribution system for various transmittable educational media. The cost of communications satellite distribution for educational programming has been high. It has, therefore, been proposed to utilize Space Shuttle related technology and Large Space Structures (LSS) to construct a system with a quantum advancement in communication capability and a quantum reduction in user cost. LSS for communications purposes have three basic advantages for both developed and emerging nations, including the ability to distribute signals over wide geographic areas, the reduced cost of satellite communications systems versus installation of land based systems, and the ability of a communication satellite system to create instant educational networks.

Joels, K. M.

1978-01-01

126

A new phase for NASA's communications satellite program  

NASA Technical Reports Server (NTRS)

NASA's research in communications satellite technology is discussed, including orbit-efficient techniques and applications by the commercial sector. Attention is given to expanding the capacities of the C-band (6-4 GHz) and the Ku-band (14-11 GHz), opening the Ka-band (30/20 GHz), broadly applied 're-use' of the spectrum, and developing multibeam spacecraft antennas with on-board switching. Increasing wideband services in video, high-speed data, and voice trunking is considered, as are narrow-band systems that may be used for data collection or public safety, with possible expansion to a thin-route satellite system. In particular, communication for medical, disaster, or search-and-rescue emergencies may be met by the integration of a satellite service with land mobile communications via terrestrial radio links. Also considered is a large geostationary platform providing electrical power, thermal rejection, and orbital station-keeping for many communications payloads.

Dement, D. K.

1980-01-01

127

The Mobile Satellite Services Market.  

ERIC Educational Resources Information Center

Mobile satellite (MSAT) technology is the basis for a new component of the telecommunications industry capable of providing services to small inexpensive subscriber terminals located almost any place in the world. The market for MSAT space segment capacity (bandwidth and power) is a natural monopoly that can be logically and technically…

Anderson, Samuel

128

The Use of Satellite for Multimedia Communications  

Microsoft Academic Search

This paper is a discussion of the issues relating to the use of satellite to deliver multimedia services. Following an introduction\\u000a to satellite services and comparison with terrestrial services, the factors affecting cost and performance are addressed and\\u000a practical examples are given. The performance of TCP over satellite is described and the use of performance enhancing proxies\\u000a investigated. The conclusion

M Fitch

2003-01-01

129

An overview of the OmniTRACS: The first operational mobile Ku-band satellite communications  

NASA Technical Reports Server (NTRS)

The service features of the OmniTRACS system developed by Omninet Communications Services of Los Angeles, California are described. This system is the first operational mobile Ku-band satellite communications system that provides two-way messaging and position determination and reporting services to mobile users on a nationwide basis. The system uses existing Ku-band satellites under a secondary international allocation for mobile satellite services.

Salmasi, Allen

1988-01-01

130

Satellite fixed communications service: A forecast of potential domestic demand through the year 2000. Volume 3: Appendices  

NASA Astrophysics Data System (ADS)

Voice applications, data applications, video applications, impacted baseline forecasts, market distribution model, net long haul forecasts, trunking earth station definition and costs, trunking space segment cost, trunking entrance/exit links, trunking network costs and crossover distances with terrestrial tariffs, net addressable forecasts, capacity requirements, improving spectrum utilization, satellite system market development, and the 30/20 net accessible market are considered.

Kratochvil, D.; Bowyer, J.; Bhushan, C.; Steinnagel, K.; Kaushal, D.; Al-Kinani, G.

1983-09-01

131

76 FR 57923 - Establishment of Rules and Policies for the Satellite Digital Audio Radio Service in the 2310...  

Federal Register 2010, 2011, 2012, 2013

...FEDERAL COMMUNICATIONS COMMISSION 47 CFR Part 25...Policies for the Satellite Digital Audio Radio Service in the...Frequency Band AGENCY: Federal Communications Commission. ACTION: Final...contained in the Satellite Digital Audio Radio Service...

2011-09-19

132

Interim Service ISDN Satellite (ISIS) hardware experiment development for advanced ISDN satellite designs and experiments  

NASA Technical Reports Server (NTRS)

The Interim Service Integrated Service Digital Network (ISDN) Satellite (ISIS) Hardware Experiment Development for Advanced Satellite Designs describes the development of the ISDN Satellite Terminal Adapter (ISTA) capable of translating ISDN protocol traffic into Time Division Multiple Access (TDMA) signals for use by a communications satellite. The ISTA connects the Type 1 Network Termination (NT1) via the U-interface on the line termination side of the CPE to the RS-499 interface for satellite uplink. The same ISTA converts in the opposite direction the RS-499 to U-interface data with a simple switch setting.

Pepin, Gerard R.

1992-01-01

133

Interim Service ISDN Satellite (ISIS) hardware experiment design for advanced ISDN satellite design and experiments  

NASA Technical Reports Server (NTRS)

The Interim Service Integrated Services Digital Network (ISDN) Satellite (ISIS) Hardware Experiment Design for Advanced Satellite Designs describes the design of the ISDN Satellite Terminal Adapter (ISTA) capable of translating ISDN protocol traffic into time division multiple access (TDMA) signals for use by a communications satellite. The ISTA connects the Type 1 Network Termination (NT1) via the U-interface on the line termination side of the CPE to the V.35 interface for satellite uplink. The same ISTA converts in the opposite direction the V.35 to U-interface data with a simple switch setting.

Pepin, Gerard R.

1992-01-01

134

Keep in Touch: Communications and Satellites  

NSDL National Science Digital Library

How do we communicate with each other? How do we communicate with people who are close by? How do we communicate with people who are far away? In this lesson, students will explore the role of communications and how satellites help people communicate with others far away and in remote areas with nothing around (i.e., no obvious telecommunications equipment). Students will learn about how engineers design satellites to benefit life on Earth. This lesson also introduces the theme of the rockets curricular unit.

Integrated Teaching And Learning Program

135

Land Mobile Satellite Service (LMSS) channel simulator: An end-to-end hardware simulation and study of the LMSS communications links  

NASA Technical Reports Server (NTRS)

The design and implementation of the Land Mobile Satellite Service (LMSS) channel simulator as a facility for an end to end hardware simulation of the LMSS communications links, primarily with the mobile terminal is described. A number of studies are reported which show the applications of the channel simulator as a facility for validation and assessment of the LMSS design requirements and capabilities by performing quantitative measurements and qualitative audio evaluations for various link design parameters and channel impairments under simulated LMSS operating conditions. As a first application, the LMSS channel simulator was used in the evaluation of a system based on the voice processing and modulation (e.g., NBFM with 30 kHz of channel spacing and a 2 kHz rms frequency deviation for average talkers) selected for the Bell System's Advanced Mobile Phone Service (AMPS). The various details of the hardware design, qualitative audio evaluation techniques, signal to channel impairment measurement techniques, the justifications for criteria of different parameter selection in regards to the voice processing and modulation methods, and the results of a number of parametric studies are further described.

Salmasi, A. B. (editor); Springett, J. C.; Sumida, J. T.; Richter, P. H.

1984-01-01

136

Satellite-aided mobile communications, experiments, applications and prospects  

NASA Technical Reports Server (NTRS)

NASA's ATS-series of satellites were used in a series of communications and position fixing experiments with automotive vehicles, ships and aircraft. Applications of the communications were demonstrated and evaluated for public services including law enforcement, search and rescue, and medical emergency, and for commercial uses in the land and maritime transportation industries. The technical success of the experiments and the demonstrated potential value of the communications prompted a study that concluded an operational satellite-aided system would be a valuable augmentation of planned trunking or cellular type terrestrial mobile radio telephone systems.

Anderson, R. E.; Frey, R. L.; Lewis, J. R.; Milton, R. T.

1980-01-01

137

Resource allocation and scheduling for communication satellites with advanced transmission antennas  

E-print Network

For multimedia and other data services over satellite networks, the efficient management of scarce satellite communication resources is critical for the economic competitiveness of the medium. To support a broad spectrum ...

Choi, Jihwan Patrick, 1975-

2006-01-01

138

Optical antenna in laser inter-satellite communication  

Microsoft Academic Search

In the modern world of telecommunications, the concept of wireless global coverage is of the utmost importance. However, real global coverage can only be achieved by satellite systems. Satellites communication is the most important mean of the communication network. The traditional satellites communication and inter-satellites links are built by microwave. In recent years, laser links for inter-satellites communication are becoming

Chuanhua Wen; Chunxia Wang; Yuquan Li

2005-01-01

139

Satellite servicing: A business opportunity?  

NASA Technical Reports Server (NTRS)

The possibilities of satellite servicing as a business opportunity are examined. The service rate which a user must be charged to yield a reasonable return is derived and then compared against the market's willingness to pay that rate. Steps taken to provide the basis from which the service rate could be derived include: (1) constructing a hypothetical on orbit servicing business offering both on orbit and associated ground services; (2) estimating the total on orbit service business potential by analyzing mission models to the year 2000; and (3) setting up ground rules to bound the conduct of the business. Using this basic information service demand (business volume) cost to set up the business, costs for operation and maintenance tax rates and desired rate of return are estimated to determine the user charge. Sensitivity of the service rate to various parameters are also assessed. The time span for the business venture runs from 1986 through 2000 with service to 1991 provided via the orbiter and by a space station beyond 1991. This point analysis shows about five years of negative cash flow, with steady profits thereafter.

Wong, R. E.; Medler, E. H.

1984-01-01

140

Mobile satellite communications in the 1990's  

NASA Astrophysics Data System (ADS)

The evolution of Inmarsat global services from a single market and single service of the 1980's to all of the key mobile markets and a wide range of new terminals and services in the 1990's is described. An overview of existing mobile satellite services, as well as new services under implementation for introduction in the near and longer term, including a handheld satellite phone (Inmarsat-P), is provided. The initiative taken by Inmarsat in the integration of its global mobile satellite services with global navigation capability derived from GPS (Global Positioning System) and the GLONASS (Russian GPS) navigation satellite systems and the provision of an international civil overlay for GPS/GLONASS integrity and augmentation is highlighted. To complete the overview of the development of mobile satellite services in the 1990's, the known national and regional mobile satellite system plans and the various recent proposals for both orbiting and geostationary satellite systems for proving handheld satellite phone and/or data messaging services are described.

Singh, Jai

1992-07-01

141

Spacecraft design project: High latitude communications satellite  

NASA Technical Reports Server (NTRS)

The spacecraft design project was part of AE-4871, Advanced Spacecraft Design. The project was intended to provide experience in the design of all major components of a satellite. Each member of the class was given primary responsibility for a subsystem or design support function. Support was requested from the Naval Research Laboratory to augment the Naval Postgraduate School faculty. Analysis and design of each subsystem was done to the extent possible within the constraints of an eleven week quarter and the design facilities (hardware and software) available. The project team chose to evaluate the design of a high latitude communications satellite as representative of the design issues and tradeoffs necessary for a wide range of satellites. The High-Latitude Communications Satellite (HILACS) will provide a continuous UHF communications link between stations located north of the region covered by geosynchronous communications satellites, i.e., the area above approximately 60 N latitude. HILACS will also provide a communications link to stations below 60 N via a relay Net Control Station (NCS), which is located with access to both the HILACS and geosynchronous communications satellites. The communications payload will operate only for that portion of the orbit necessary to provide specified coverage.

Josefson, Carl; Myers, Jack; Cloutier, Mike; Paluszek, Steve; Michael, Gerry; Hunter, Dan; Sakoda, Dan; Walters, Wes; Johnson, Dennis; Bauer, Terry

1989-01-01

142

A personal communications network using a Ka-band satellite  

NASA Technical Reports Server (NTRS)

The feasibility of portable communications terminals that can provide 4.8-kbps voice communications to a hub station via a Ka-band geosynchronous satellite was investigated. Tradeoffs are examined so that the combined system of the hub and gateway earth stations, the satellite, and the personal terminals can provide a competitive service in terms of cost, availability, and quality. A baseline system is described using a spacecraft with approximately 140 spot beams that cover CONUS with 5-watt power amplifiers in each beam. Satellite access in both the forward and return directions uses Frequency Division Multiple Access/Code Division Multiple Access (FDMA/CDMA) with a chip rate of 2.5 Mchip/sec. An experiment is recommended using the Advanced Communications Technology Satellite (ACTS) to demonstrate some of the features of the portable terminal concept.

Palmer, L. C.; Stern, A.; Sohn, P. Y.

1991-01-01

143

Overview of the Anik C satellites and services  

NASA Astrophysics Data System (ADS)

An overview of the important technical characteristics of the Anik C series of Canadian communications satellites is presented. The system was launched as part of the Telesat Communications payload of the Space Shuttle in 1982. Among the services the system will in the near future provide are: a 27 MHz channel bandwidth television service for pay-TV distribution in Canada; two TV channels for hockey broadcasts and a transportable TV system; a heavy-voice route telephone service for five major Canadian cities; and a telephone system for business voice and data communications. Services anticipated for Anik-C satellites later in the decade include a Single Channel Per Carrier (SCPC) voice and data communications system for British Columbia and the Maritime Provinces, and a direct-to-home broadcast service to be sold to television markets in the United States.

Smart, F. H.

144

The role of rain in satellite communications  

Microsoft Academic Search

The most fundamental obstacle encountered in design of satellite communication systems at frequencies above 10 GHz is attenuation by rain. The microwave power radiated toward an earth station, being limited by factors such as available primary power and size of antenna on the satellite, is insufficient, with present technology, to overcome the large attenuation produced by intense rain cells on

D. C. Hogg; Ta-Shing Chu

1975-01-01

145

Narrow-Band Applications of Communications Satellites.  

ERIC Educational Resources Information Center

This paper attempts to describe the advantages of "narrow-band" applications of communications satellites for education. It begins by discussing the general controversy surrounding the use of satellites in education, by placing the concern within the larger context of the general debate over the uses of new technologies in education, and by…

Cowlan, Bert; Horowitz, Andrew

146

Satellite Communication and Development: A Reassessment.  

ERIC Educational Resources Information Center

The potential benefits of satellite communications development have been recognized since the notion of a geostationary "space platform" was proposed by Arthur C. Clarke in 1945. Although there have been examples of developmental applications of satellite technology, the promise has been slow in being fulfilled. The history of the application of…

Hudson, Heather E.

147

Introduction to Satellite Communications Technology for NREN  

NASA Technical Reports Server (NTRS)

NREN requirements for development of seamless nomadic networks necessitates that NREN staff have a working knowledge of basic satellite technology. This paper addresses the components required for a satellite-based communications system, applications, technology trends, orbits, and spectrum, and hopefully will afford the reader an end-to-end picture of this important technology.

Stone, Thom

2004-01-01

148

The Arctic Regional Communications Small SATellite (ARCSAT)  

NASA Technical Reports Server (NTRS)

Traditional satellite missions are extremely complex and expensive to design, build, test, launch and operate. Consequently many complementary operational, exploration and research satellite missions are being formulated as a growing part of the future space community capabilities using formations of small, distributed, simple to launch and inexpensive highly capable small scale satellites. The Arctic Regional Communications small SATellite (ARCSAT) initiative would launch a Mini-Satellite "Mothership" into Polar or Sun Sync low-earth-orbit (LEO). Once on orbit, the Mothership would perform orbital insertion of four internally stored independently maneuverable nanosatellites, each containing electronically steerable antennas and reconfigurable software-defined radios. Unlike the traditional geostationary larger complex satellite communication systems, this LEO communications system will be comprised of initially a five small satellite formation that can be later incrementally increased in the total number of satellites for additional data coverage. ARCSAT will provide significant enabling capabilities in the Arctic for autonomous voice and data communications relay, Maritime Domain Awareness (MDA), data-extraction from unattended sensors, and terrestrial Search & Rescue (SAR) beacon detection missions throughout the "data starved desert" of the Arctic Region.

Casas, Joseph; Kress, Martin; Sims, William; Spehn, Stephen; Jaeger, Talbot; Sanders, Devon

2013-01-01

149

STS-5 deployment of communications satellites  

NASA Technical Reports Server (NTRS)

The Telesat Canada ANIK C-3 communications satellite rises from its protective 'cradle' (obscured by another such device in the foreground) in the cargo bay of the Space Shuttle Columbia. The empty, closed shield in the cargo bay (foreground) earlier had protected Satellite Business Systems (SBS-3) satellite. Both orbital maneuvering system (OMS) pods, part of the vertical tail and part of the wing stand out in this photo.

1982-01-01

150

Polarization tracking for quantum satellite communications  

NASA Astrophysics Data System (ADS)

Satellite networks and quantum communications offer complementary opportunities for enhanced operations. Quantum communications provide security for the transmissions between satellites and ground stations; while the free-space link of satellite networks provide the potential of long distance transmission of quantum bits (qubit) for space communications. However, with the promising advantages of the two approaches, challenges remain to fully develop quantum-based satellite communications such as robust and reliable information detection which is difficult to achieve due to the movement of satellites. In this paper, a tracking algorithm is proposed for polarization-encoded quantum satellite communications where polarization states are used to determine the bit transfer between the transmitter and receiver. The polarization tracking is essential for the decoding of a qubit and the quantum key distribution (QKD). A practical channel model for free-space quantum communications is adopted in this paper. With the estimated polarization, a novel dynamic polarization compensation scheme is also proposed. The results show that our methods can accurately estimate the polarization, providing much lower quantum bit error rate (QBER) by compensation, as compared with the direct qubit detection without polarization tracking and compensation scheme.

Wang, Gang; Shen, Dan; Chen, Genshe; Pham, Khanh; Blasch, Erik

2014-06-01

151

Soviet satellite communications science and technology  

SciTech Connect

This is a report by six US scientists and engineers concerning the current state of the art and projections of future Soviet satellite communications technologies. The panel members are experts in satellite stabilization, spacecraft environments, space power generation, launch systems, spacecraft communications sciences and technologies, onboard processing, ground stations, and other technologies that impact communications. The panel assessed the Soviet ability to support high-data-rate space missions at 128 Mbps by evaluating current and projected Soviet satellite communications technologies. A variety of space missions were considered, including Earth-to-Earth communications via satellites in geostationary or highly elliptical orbits, those missions that require space-to-Earth communications via a direct path and those missions that require space-to-Earth communications via a relay satellite. Soviet satellite communications capability, in most cases, is 10 years behind that of the United States and other industrialized nations. However, based upon an analysis of communications links needed to support these missions using current Soviet capabilities, it is well within the current Soviet technology to support certain space missions outlined above at rates of 128 Mbps or higher, although published literature clearly shows that the Soviet Union has not exceeded 60 Mbps in its current space system. These analyses are necessary but not sufficient to determine mission data rates, and other technologies such as onboard processing and storage could limit the mission data rate well below that which could actually be supported via the communications links. Presently, the Soviet Union appears to be content with data rates in the low-Earth-orbit relay via geostationary mode of 12 Mbps. This limit is a direct result of power amplifier limits, spacecraft antenna size, and the utilization of K{sub u}-band frequencies. 91 refs., 16 figs., 15 tabs.

Birch, J.N.; Campanella, S.J.; Gordon, G.D.; McElroy, D.R.; Pritchard, W.L.; Stamminger, R.

1991-08-01

152

Low Earth Orbit satellite/terrestrial mobile service compatibility  

NASA Technical Reports Server (NTRS)

Currently the geostationary type of satellite is the only one used to provide commercial mobile-satellite communication services. Low earth orbit (LEO) satellite systems are now being proposed as a future alternative. By the implementation of LEO satellite systems, predicted at between 5 and 8 years time, mobile space/terrestrial technology will have progressed to the third generation stage of development. This paper considers the system issues that will need to be addressed when developing a dual mode terminal, enabling access to both terrestrial and LEO satellite systems.

Sheriff, Ray E.; Gardiner, John G.

1993-01-01

153

Deployment of the SBS-4 communications satellite  

NASA Technical Reports Server (NTRS)

Deployment of the SBS-4 communications satellite by the STS 41-D crew. The cylindrical spacecraft spins and rises from the its protective shield in the space shuttle payload bay. Behind it is another, closed protective cradle for the Syncom IV communications satllite. The earth's surface can be seen to the left of the frame.

1984-01-01

154

Personal Communications via Acts Satellite Hbr Transponders.  

National Technical Information Service (NTIS)

The concept of a fully meshed network of briefcase-sized terminals is presented for personal communications over Ka-band satellite transponders. In this concept, undesirable double-hop delays are avoided for voice communications. The bandwidth and power r...

R. J. F. Fang

1991-01-01

155

Satellite Communications in the 1980's.  

ERIC Educational Resources Information Center

Space communications have developed tremendously since 1963 when the National Aeronautics and Space Administration (NASA) launched the synchronous communication satellite, Syncom II, into geostationary orbit. The capacity of that spacecraft was one two-circuit voice channel. Intelsat V, launched in 1980, has a capacity of 12,000 circuits plus two…

Usunier, Pierre

156

Developments in land mobile satellite service in Europe  

NASA Technical Reports Server (NTRS)

The evolution of land mobile radio has reached a stage to benefit from satellite communications. The provision of a service on a pan-European basis makes the use of satellites a viable proposition. The paper describes the European position on both system and space segment aspects of the land mobile satellite service. Also, some of the functions of the European institutions, such as the European Telecommunications Standards Institute (ETSI), the Conference of European Postal and Telecommunications Administrations (CEPT), and the Commission of European Communities (CEC), in establishing these services are identified.

Jayasuriya, D. A. R.

1990-01-01

157

High-Latitude Communications Satellite (HILACS)  

NASA Technical Reports Server (NTRS)

The Naval Postgraduate School in the AE 4871 Advanced Spacecraft Design course designed a communications satellite (HILACS) that will provide a continuous UHF communications link between stations located north of the region covered by geosynchronous communications satellites. The communications payload will operate only for that portion of the orbit necessary to provide specific coverage. The satellite orbit is elliptic with perigee at 1204 km in the Southern Hemisphere and an apogee at 14,930 km with 63.4 degrees inclination. Analysis and design of each of the subsystems was done to the extent possible within the constraints of an eleven week quarter and the design and analysis tools available. Work was completed in orbital analysis, the reaction control system, attitude control subsystem, electric power subsystem, telemetry, tracking, and control, thermal control subsystem, and the structures subsystem. The design team consisted of 12 students. Additional support was provided by the Jet Propulsion Laboratory and the Naval Research Laboratory.

1990-01-01

158

Satellite services system analysis study. Volume 3: Service equipment requirements  

NASA Technical Reports Server (NTRS)

Service equipment mission requirements are discussed. On-orbit operations, satellite classes, and reference missions are included. Service equipment usage and requirements are considered. Equipment identification methodology is discussed. Service equipment usage is analyzed, including initial launch, revisit, Earth return, and orbital storage. A summary of service requirements and equipment is presented, including service equipment status, even interaction, satellite features, and observations.

1981-01-01

159

The use of satellites in non-goestationary orbits for unloading geostationary communication satellite traffic peaks. Volume 2: Technical report  

NASA Technical Reports Server (NTRS)

The part of the geostationary (GEO) orbital arc used for United States domestic fixed, communications service is rapidly becoming filled with satellites. One of the factors currently limiting its utilization is that communications satellites must be designed to have sufficient capacity to handle peak traffic leads, and thus are under utilized most of the time. A solution is to use satellites in suitable non-geostationary orbits to unload the traffic peaks. Three different designs for a non-geostationary orbit communications satellite system are presented for the 1995 time frame. The economic performance is analyzed and compared with geostationary satellites for two classes of service, trunking and customer premise service. The result is that the larger payload of the non-geostationary satellite offsets the burdens of increased complexity and worse radiation environment to give improved economic performance. Depending on ground terminal configuration, the improved economic performance of the space segment may be offset by increased ground terminal expenses.

Price, K.; Turner, A.; Nguyen, T.; Doong, W.; Weyandt, C.

1987-01-01

160

Satellite utilization for educational communications in the U.S.  

NASA Technical Reports Server (NTRS)

This paper summarizes completed, continuing and planned satellite experiments in the U.S. related to the delivery of educational services and networking. It also describes some results of an on-going study at Washington University directed towards defining applications of fixed/broadcast communication satellites in the U.S. and alternative systems and strategies for large-scale telecommunication-based educational delivery systems utilizing satellites. An analysis is presented of recent actions which may influence future development of such systems.

Morgan, R. P.; Singh, J. P.

1974-01-01

161

The Globalstar mobile satellite system for worldwide personal communications  

NASA Technical Reports Server (NTRS)

Loral Aerospace Corporation along with Qualcomm Inc. have developed a satellite system which offers global mobile voice and data services to and from handheld and mobile user terminals with omni-directional antennas. By combining the use of low-earth orbit (LEO) satellites with existing terrestrial communications systems and innovative, highly efficient spread spectrum techniques, the Globalstar system provides users with low-cost, reliable communications throughout the world. The Globalstar space segment consists of a constellation of 48 LEO satellites in circular orbits with 750 NM (1389 km) altitude. Each satellite communicates with the mobile users via the satellite-user links and with gateway stations. The gateway stations handle the interface between the Globalstar network and the OSTN/PLMN systems. Globalstar transceivers are similar to currently proposed digital cellular telephones in size and have a serial number that will allow the end user to make and receive calls from or to that device anywhere in the world. The Globalstar system is designed to operate as a complement to existing local, long-distance, public, private and specialized telecommunications networks. Service is primarily designed to serve the rural and thin route communications needs of consumers, government users, and private networks.

Wiedeman, Robert A.; Viterbi, Andrew J.

1993-01-01

162

Use of low orbital satellite communications systems for humanitarian programs  

NASA Technical Reports Server (NTRS)

Communication and information exchange play a decisive role in progress and social development. However, in many parts of the world the communication infrastructure is inadequate and the capacity for on-line exchange of information may not exist. This is true of underdeveloped countries, remote and relatively inaccessible regions, sites of natural disasters, and of all cases where the resources needed to create complex communication systems are limited. The creation of an inexpensive space communications system to service such areas is therefore a high priority task. In addition to a relatively low-cost space segment, an inexpensive space communications systems requires a large number of ground terminals, which must be relatively inexpensive, energy efficient (using power generated by storage batteries, or solar arrays, etc.), small in size, and must not require highly expert maintenance. The ground terminals must be portable, and readily deployable. Communications satellites in geostationary orbit at altitudes of about 36,000 km are very expensive and require complex and expensive ground stations and launch vehicles. Given current technology, it is categorically impossible to develop inexpensive satellite systems with portable ground terminals using such satellites. To solve the problem of developing an inexpensive satellite communications system that can operate with relatively small ground stations, including portable terminals, we propose to use a system with satellites in low Earth orbit, at an altitude of 900-1500 km. Because low orbital satellites are much closer to the Earth than geostationary ones and require vastly less energy expenditure by the satellite and ground terminals for transmission of messages, a system using them is relatively inexpensive. Such a system could use portable ground terminals no more complex than ordinary mobile police radios.

Vlasov, Vladimir N.; Gorkovoy, Vladimir

1991-01-01

163

Photogrammetric mobile satellite service prediction  

NASA Technical Reports Server (NTRS)

Photographic images of the sky were taken with a camera through a fisheye lens with a 180 deg field-of-view. The images of rural, suburban, and urban scenes were analyzed on a computer to derive quantitative information about the elevation angles at which the sky becomes visible. Such knowledge is needed by designers of mobile and personal satellite communications systems and is desired by customers of these systems. The 90th percentile elevation angle of the skyline was found to be 10 deg, 17 deg, and 51 deg in the three environments. At 8 deg, 75 percent, 75 percent, and 35 percent of the sky was visible, respectively. The elevation autocorrelation fell to zero with a 72 deg lag in the rural and urban environment and a 40 deg lag in the suburb. Mean estimation errors are below 4 deg.

Akturan, Riza; Vogel, Wolfhard J.

1994-01-01

164

Modeling of terrains for simulation of integrated mobile terrestrial and satellite communications systems  

Microsoft Academic Search

In this paper we present methods to generate models of mountainous regions. For these regions statistical methods are unsuitable to predict the service coverage, blocking and termination probabilities for systems involving fast moving satellites. We present methods using modeled terrains to analyze the service coverage in satellite integrated mobile communications systems. Results of service coverage analyses based on these methods

Gunar Schorcht; Ulrich Freund; Horst Salzwedel; Harald Keller

1996-01-01

165

Satellite broadcasting - Capabilities for public service  

NASA Technical Reports Server (NTRS)

Satellite broadcast services to support health-care and educational transmissions must work with small, low-cost terminals in allocated radio-frequency bands. The ATS-6 spacecraft has successfully demonstrated such capability in the bands of non-technical users. It supports interactive television broadcasting to simple, low-cost terminals in a nationwide series of experiments in the delivery of health-care and educational services. ATS-6 achieves this capability with a very large antenna and moderate transmitter power. The coverage limitations inherent in this approach will be overcome by the joint U.S.-Canadian Communications Technology Satellite to be launched in December 1975. The CTS will demonstrate broadcast capability with new, high-power technology in a newly-allocated radio-frequency band. This will make it possible to use smaller antennas, greatly enlarging the area coverage available to the many nontechnical experimenters using CTS for their own needs. A practical application of these technologies is now in development for operational broadcasting services in Japan.

Marsten, R. B.

1975-01-01

166

Silicon-Germanium Fast Packet Switch Developed for Communications Satellites  

NASA Technical Reports Server (NTRS)

Emerging multimedia applications and future satellite systems will require high-speed switching networks to accommodate high data-rate traffic among thousands of potential users. This will require advanced switching devices to enable communication between satellites. The NASA Lewis Research Center has been working closely with industry to develop a state-of-the-art fast packet switch (FPS) to fulfill this requirement. Recently, the Satellite Industry Task Force identified the need for high-capacity onboard processing switching components as one of the "grand challenges" for the satellite industry in the 21st century. In response to this challenge, future generations of onboard processing satellites will require low power and low mass components to enable transmission of services in the 100 gigabit (1011 bits) per second (Gbps) range.

Quintana, Jorge A.

1999-01-01

167

Connection Protocol For Mobile/Satellite Communications  

NASA Technical Reports Server (NTRS)

Throughput increased by better resolution of competing simultaneous requests for connections. Improved protocol sorts out simultaneous competing requests by message-originating stations for connection to satellite transmission link of land-mobile/satellite digital communication system. Applies to multiple-channel packet-message system with synchronous timeslots on all channels. Communication system has Q channels. Transmissions of packets allowed to begin only at beginnings of timeslots. Provides, to all users, binary feedback information on state of channel - namely, whether or not there is collision - during each timeslot.

Tan, Harry H.; Yan, Tsun-Yee

1990-01-01

168

Von Karman Lecture - The rocky road to communication satellites  

NASA Astrophysics Data System (ADS)

The history of communications satellites traced in terms of the confluence of the forces of technology, economics and public policy is discussed. The idea of placing communications satellites in GEO was put forward by a science fiction writer in 1945. Syncom II was launched, with a TWT amplifier, into GEO in 1963. Telstar provided the first live transoceanic broadcasts in 1962, just before Comsat was chartered. Early Bird proved that telephony links through GEO satellites was feasible. The follow-up, Intelsat II, was partially spurred by the Apollo program with its worldwide communications demands. Intelsat began with three spacecraft that formed the foundation for the present system. The Intelsat monopoly on worldwide common carrier links is being challenged by ground-based links and entrepreneurial activities spurred by deregulation. An open-skies policy formulated in the U.S. in the late 1960s has led to the launch of various domestic satellite systems with narrow beam transmissions using C- and Ku-band frequencies. Satellite access costs have fallen because of the capabilities of renting or selling individual transponders. Mobile communications systems may soon be served through a joint U.S.-Canada project. Finally, the WARC 1977 set the ground rules for DBS television service, which is in the process of being implemented, mainly by cable operators.

Wheelon, A. D.

1986-01-01

169

A framework for implementing data services in multi-service mobile satellite systems  

Microsoft Academic Search

Mobile satellite systems being planned for introduction in the early 1990s are expected to be invariably of the multi-service type. Mobile Telephone Service (MTS), Mobile Radio Service (MRS), and Mobile Data Service (MDS) are the major classifications used to categorize the many user applications to be supported. The MTS and MRS services encompass circuit-switched voice communication applications, and may be

Mohammed O. Ali; Victor C. M. Leung; Andrew I. Spolsky

1988-01-01

170

My Own Communication Service Provider  

Microsoft Academic Search

The World Wide Web has become an important platform for delivering services in the last decade. Openness and flexibility are indeed key factors for the success of the Web where end-users develop applications freely. As a consequence, end-users become producers and consumers of contents and services. End-users rely for their communication needs on communication platforms (CPs). CPs managed by Service

Sivasothy Shanmugalingam; Noel Crespi; Paul Labrogere

2010-01-01

171

The future role of satellite communications in an improved air traffic management  

NASA Astrophysics Data System (ADS)

The need for air to ground communication in Air Traffic Control (ATC) is discussed and a summary on the birth of aeronautical satellite communication is given. The standardization of an aeronautical mobile communications service by the International Civil Aviation Organization is reported. The feasibility analysis of satellite communications for ATC carried out by the French civil aviation is described. This 'South Pacific Trial' is regarded as a first step towards a full operational implementation.

Gauthier, Patrice

1992-07-01

172

Viterbi Decoding for Satellite and Space Communication  

Microsoft Academic Search

Convolutional coding and Viterbi decoding, along with binary phase-shift keyed modulation, is presented as an efficient system for reliable communication on power limited satellite and space channels. Performance results, obtained theoretically and through computer simulation, are given for optimum short constraint length codes for a range of code constraint lengths and code rates. System efficiency is compared for hard receiver

J. Heller; I. Jacobs

1971-01-01

173

Domestic satellite communications - The Canadian experience  

Microsoft Academic Search

The history of commercial satellite communications in Canada is surveyed. The benefits provided by the existing system are illustrated by focusing on the experience of a particular Arctic hamlet (Pangnirtung). Attention is given to the factors that have differentiated the Canadian system from the American one (smaller, less homogenous, and more widely dispersed population). The problem posed by 'pirate' earth

D. A. Golden

1980-01-01

174

Satellite Communications technological advancements in Latin America  

Microsoft Academic Search

Although rightly associated as a region historically fraught with change and turmoil, Latin America has been able to radically transform itself over the past two decades and increasingly become a leader in technological development. One key area of growth has been the rapid advance of satellite communications. It seems that at the current pace, the region will quickly reach the

Abdulrahman Yarali; Sebastian Coe

2009-01-01

175

Securing multimedia services over satellite ATM networks  

Microsoft Academic Search

1. SUMMARY In recent years, there has been increasing interest in interconnecting satellite and ATM networks because both share common characteristics of the ability to provide bandwidth-on-demand and flexibility of integrating voice, video and data services. There are several new satellite constellation proposals that support multimedia service and transport ATM traffic. For a successful implementation of such systems, it is

H. Cruickshank; I. Mertzanis; B. G. Evans; H. Leitold; R. Posch

1998-01-01

176

Performance of Duplex Communication between a Leo Satellite and Terrestrial Location Using a Geo Constellation  

NASA Technical Reports Server (NTRS)

A network comprised of a terrestrial site, a constellation of three GEO satellites and a LEO satellite is modeled and simulated. Continuous communication between the terrestrial site and the LEO satellite is facilitated by the GEO satellites. The LEO satellite has the orbital characteristics of the International Space Station. Communication in the network is based on TCP/IP over ATM, with the ABR service category providing the QoS, at OC-3 data rate. The OSPF protocol is used for routing. We simulate FTP file transfers, with the terrestrial site serving as the client and the LEO satellite being the server. The performance characteristics are presented.

Robinson, Daryl C.; Konangi, Vijay K.; Wallett, Thomas M.

1998-01-01

177

Management and Service Discovery in Satellite and Avionic Networks  

E-print Network

. Lockwood Department of Computer Science and Engineering Washington University in Saint Louis St. Louis, MO of both satellite and aircraft links to provide services that best sat- isfy the immediate needs of ground on the ground. UAVs are used to analyze pollution, relay communications and host a variety of sensors

Lockwood, John W.

178

Protocol design for mobile radio group communications over satellite  

Microsoft Academic Search

The protocol design for a mobile radio service supporting half-duplex push-to-talk voice communications over mobile satellite systems is presented. Two types of protocols are considered, namely, a demand assignment multiple access protocol to assign channels only to those user groups in active sessions of conversations and a signaling protocol to arbitrate contentions among members of the same user group within

Victor C. M. Leung

1992-01-01

179

Satellite mobile data service for Canada  

NASA Technical Reports Server (NTRS)

A commercial mobile satellite system which is to be constructed and operated in Canada is examined. This is done in two phases. First, mobile data services was introduced. Hub equipment and 3000 mobile data terminals were supplied. Over the satellite tests were performed. The mobile data service provides full two way digital messaging automatic vehicle location and fleet management services. The second phase is to construct, launch and make operational the MSAT satellite and associated network control facilities. The implementation is examined of the mobile data service in Canada, including the technical description. Marketing and applications are also examined.

Egan, Glenn R.; Sward, David J.

1990-01-01

180

Annual Survey of Communication Services  

NSDL National Science Digital Library

The Census Bureau has released findings for selected United States communications industry groups from 1995 to 1996. Telephone communication revenues showed an increase of 10 percent while radio and television broadcasting services increased 9 percent. Cable and other pay television services grew the most in 1996 with total revenues of $38 Billion at an increase of 14 percent. Overall, the industry boomed in 1996 with revenues of more than $322 billion.

181

“KUPON” spacecraft of “Bankir” satellite communication and data transmitting system  

Microsoft Academic Search

The “KUPON” spacecraft is designed for data retranslation (data transmission, telefax, telephone) between subscribers of the satellite communication network. It was developed for the “Bankir” satellite communication and data transmitting system of the Central Bank of Russian Federation. The spacecraft was designed on the basis of the Lavochkin satellite communications. That has led to a decrease in terms of development

S. D. Koulikov; K. M. Pitchkhadze; V. I. Makarov; V. I. Kouznetsov

1998-01-01

182

Command and Service Module Communications  

NASA Technical Reports Server (NTRS)

This viewgraph presentation examines Command and Service Module (CSM) Communications. The communication system's capabilities are defined, including CSM-Earth, CSM-Lunar Module and CSM-Extravehicular crewman communications. An overview is provided for S-band communications, including data transmission and receiving rates, operating frequencies and major system components (pre-modulation processors, unified S-band electronics, S-band power amplifier and S-band antennas). Additionally, data transmission rates, operating frequencies and the capabilities of VHF communications are described. Major VHF components, including transmitters and receivers, and the VHF multiplexer and antennas are also highlighted. Finally, communications during pre-launch, ascent, in-flight and entry are discussed. Overall, the CSM communication system was rated highly by flight controllers and crew. The system was mostly autonomous for both crew and flight controllers and no major issues were encountered during flight.

Interbartolo, Michael

2009-01-01

183

Satellite switched FDMA advanced communication technology satellite program  

NASA Technical Reports Server (NTRS)

The satellite switched frequency division multiple access system provided a detailed system architecture that supports a point to point communication system for long haul voice, video and data traffic between small Earth terminals at Ka band frequencies at 30/20 GHz. A detailed system design is presented for the space segment, small terminal/trunking segment at network control segment for domestic traffic model A or B, each totaling 3.8 Gb/s of small terminal traffic and 6.2 Gb/s trunk traffic. The small terminal traffic (3.8 Gb/s) is emphasized, for the satellite router portion of the system design, which is a composite of thousands of Earth stations with digital traffic ranging from a single 32 Kb/s CVSD voice channel to thousands of channels containing voice, video and data with a data rate as high as 33 Mb/s. The system design concept presented, effectively optimizes a unique frequency and channelization plan for both traffic models A and B with minimum reorganization of the satellite payload transponder subsystem hardware design. The unique zoning concept allows multiple beam antennas while maximizing multiple carrier frequency reuse. Detailed hardware design estimates for an FDMA router (part of the satellite transponder subsystem) indicate a weight and dc power budget of 353 lbs, 195 watts for traffic model A and 498 lbs, 244 watts for traffic model B.

Atwood, S.; Higton, G. H.; Wood, K.; Kline, A.; Furiga, A.; Rausch, M.; Jan, Y.

1982-01-01

184

Need for, and financial feasibility of, satellite-aided land mobile communications  

NASA Technical Reports Server (NTRS)

Questions regarding the role of a mobile-satellite system in augmenting the terrestrial communications system are considered, and a market assessment study is discussed. Aspects of an investment analysis are examined, taking into account a three phase financial study of four postulated land Mobile Satellite Service (LMSS) systems, project profitability evaluation methods, risk analysis methods, financial projections, potential investor acceptance standards, and a risk analysis. It is concluded that a satellite augmented terrestrial mobile service appears to be economically and technically superior to a service depending exclusively on terrestrial systems. The interest in the Mobile Satellite Service is found to be worldwide, and the ground equipment market is potentially large.

Castruccio, P. A.; Marantz, C. S.; Freibaum, J.

1982-01-01

185

Satellite communication from user to user  

Microsoft Academic Search

Satellite communication systems which allow a multitude of user-to-user, point-to-point, and multipoint connections, are presented. The bit rates are 64 kbit\\/sec and multiples, up to 1.92 Mbit\\/sec. If required, the ground-stations are installed at the customer's site or at suitable locations in order to serve several customers. However, technical requirements for station location have also to be fulfulled, in order

Manfred Gern

1986-01-01

186

Intersatellite link application to commercial communications satellites  

NASA Technical Reports Server (NTRS)

The fundamental characteristics of intersatellite link (ISL) systems, and their application to domestic, regional, and global satellite communications, are described. The quantitative advantages of using ISLs to improve orbit utilization, spectrum occupancy, transmission delay (compared to multi-hop links), coverage, and connectivity, and to reduce the number of earth station antennas, are also presented. Cost-effectiveness and other systems benefits of using ISLs are identified, and the technical and systems planning aspects of ISL systems implementation are addressed.

Lee, Young S.; Atia, Ali E.; Ponchak, Denise S.

1988-01-01

187

Forecast of space shuttle flight requirements for launch of commercial communications satellites  

NASA Technical Reports Server (NTRS)

The number of communication satellites required over the next 25 years to support domestic and regional communication systems for telephony, telegraphy and other low speed data; video teleconferencing, new data services, direct TV broadcasting; INTELSAT; and maritime and aeronautical services was estimated to determine the number of space shuttle flights necessary for orbital launching.

1977-01-01

188

Land mobile communications satellite mission (LAMOCOSAMIS) Task 1: Market study  

NASA Astrophysics Data System (ADS)

Land mobile communication service demand in Europe and the Mediterranean basin in the years 1995-2005 was estimated. A traffic model was derived. There is an exploding demand for land mobile communications in Europe, with overwhelming preference for two way telephone services. The users survey shows a surprising lack of sensitivity to prices and tariffs, which widely contributed to the preeminence of the needs for telephone services. This demand justifies that every effort be made to develop as fast as possible a compatible pan-European terrestrial mobile system. If a large proportion of the needs may be satisfied by terrestrial mobile system solutions, the potential remaining needs for telephony, outside of the presently planned terrestrial mobile, which can be served only by satellite, even under the pessimistic economic scenario and high cost/tariff assumptions, requires a number of equivalent telephone circuits which cannot be achieved with available state of the art technology.

1985-12-01

189

HR SERVICES COMMUNICATION SESSION  

E-print Network

;Completed Projects 2013 · Data Cleansing ­ ­ New Processes Implementation ­ Audit Reports · Core Upgrade Level Agreement · Recruitment KPIs · HRIS KPIs #12;HR Services Projects ­ 2013 DMS Core Data Cleansing

190

Vibration noise control in laser satellite communication  

NASA Astrophysics Data System (ADS)

Laser satellite communication has become especially attractive in recent years. Because the laser beam width is narrow than in the RF or microwave range, the transmitted optical power may be significantly reduced. This leads to development of miniature communication systems with extremely low power consumption. On the other hand, the laser communication channel is very sensitive to vibrations of the optical platform. These vibrations cause angular noise in laser beam pointing, comparable to the laser beam width. As result, as significant portion of the optical power between transmitter and receiver is lost and the bit error rate is increased. Consequently, vibration noise control is a critical problem in laser satellite communication. The direction of the laser beam is corrected with a fast steering mirror (FSM). In this paper are presented two approaches for the FSM control. One is the feedback control that uses an LQG algorithm. The second is the direct feed- forward control when vibration noise is measured by three orthogonal accelerometers and drives directly the F SM. The performances of each approach are evaluated using MATLAB simulations.

Saksonov, Avigdor; Shlomi, Arnon; Kopeika, Norman S.

2001-08-01

191

Concept for advanced satellite communications and required technologies  

NASA Technical Reports Server (NTRS)

The advanced communications technology satellite (ACTS) program of NASA is aimed at the development of high risk technologies that will enable exploiting higher frequency bands and techniques for improving frequency reuse. The technologies under development include multiple beam spacecraft antennas, on-board switching and processing, RF devices and components and advanced Earth stations. The program focus is on the Ka-band (30/20 GHz) as the implementing frequency since it has five times the bandwidth of either the C- or Ku-bands. However, the technology being developed is applicable to other frequency bands as well and will support a wide range of future communications systems required by NASA, other Government agencies and the commercial sector. An overview is presented of an operational 30/20 GHz satellite system that may evolve. How the system addresses service requirements is discussed, and the technology required and being developed is considered.

Ramler, J. R.; Salzman, J. A.

1982-01-01

192

FEC decoder design optimization for mobile satellite communications  

NASA Technical Reports Server (NTRS)

A new telecommunications service for location determination via satellite is being proposed for the continental USA and Europe, which provides users with the capability to find the location of, and communicate from, a moving vehicle to a central hub and vice versa. This communications system is expected to operate in an extremely noisy channel in the presence of fading. In order to achieve high levels of data integrity, it is essential to employ forward error correcting (FEC) encoding and decoding techniques in such mobile satellite systems. A constraint length k = 7 FEC decoder has been implemented in a single chip for such systems. The single chip implementation of the maximum likelihood decoder helps to minimize the cost, size, and power consumption, and improves the bit error rate (BER) performance of the mobile earth terminal (MET).

Roy, Ashim; Lewi, Leng

1990-01-01

193

Channel simulation to facilitate mobile-satellite communications research  

NASA Technical Reports Server (NTRS)

The mobile-satellite-service channel simulator, which is a facility for an end-to-end hardware simulation of mobile satellite communications links is discussed. Propagation effects, Doppler, interference, band limiting, satellite nonlinearity, and thermal noise have been incorporated into the simulator. The propagation environment in which the simulator needs to operate and the architecture of the simulator are described. The simulator is composed of: a mobile/fixed transmitter, interference transmitters, a propagation path simulator, a spacecraft, and a fixed/mobile receiver. Data from application experiments conducted with the channel simulator are presented; the noise converison technique to evaluate interference effects, the error floor phenomenon of digital multipath fading links, and the fade margin associated with a noncoherent receiver are examined. Diagrams of the simulator are provided.

Davarian, Faramaz

1987-01-01

194

An experiment to enable commercial mobile satellite service  

NASA Astrophysics Data System (ADS)

A Mobile Satellite Experiment (MSAT-X) is described, based on a planned cooperative U.S./Canadian program. The experiment would establish network architecture, develop system and ground-segment technology, and define the technical characteristics needed to help structure the regulatory/institutional framework needed to enable a first-generation commercial satellite service. A satellite of this type would augment terrestrial systems, both cellular and noncellular, in the thin-route/rural areas of the country where service is either unavailable or inadequate. Applications range from wide-area radio/dispatch (e.g., oil exploration and interstate trucking) to extension of the public mobile telephone service. Market estimates are provided and experiment objectives and requirements are delineated. The requirements are being developed in close coordination with the Department of Communications (DOC) of Canada and with industry and potential-user organizations. The paper closes with a development plan and milestone chart.

Lovell, R. R.; Knouse, G. H.; Weber, W. J.

195

An experiment to enable commercial mobile satellite service  

NASA Technical Reports Server (NTRS)

A Mobile Satellite Experiment (MSAT-X) is described, based on a planned cooperative U.S./Canadian program. The experiment would establish network architecture, develop system and ground-segment technology, and define the technical characteristics needed to help structure the regulatory/institutional framework needed to enable a first-generation commercial satellite service. A satellite of this type would augment terrestrial systems, both cellular and noncellular, in the thin-route/rural areas of the country where service is either unavailable or inadequate. Applications range from wide-area radio/dispatch (e.g., oil exploration and interstate trucking) to extension of the public mobile telephone service. Market estimates are provided and experiment objectives and requirements are delineated. The requirements are being developed in close coordination with the Department of Communications (DOC) of Canada and with industry and potential-user organizations. The paper closes with a development plan and milestone chart.

Lovell, R. R.; Knouse, G. H.; Weber, W. J.

1982-01-01

196

Leveraging Commercial Communication Satellites to support the Space Situational  

NASA Astrophysics Data System (ADS)

The majority of USSTRATCOM detect and track requirements in the geosynchronous regime could be met via strategic placement of medium grade optical sensors on select geosynchronous satellites at relatively low cost in less than 48 months. An architecture which includes hosting SSA sensors on eight to ten commercial communication satellites could provide for highly accurate, timely and relatively inexpensive detect and track capabilities. The major factors considered when hosting any sensor on a commercial communications satellite are size, weight (mass) and power or SWAP. Additional sensor specific items must also be considered to form a complete feasibility analysis. These include data rate, mounting constraints, thermal balance, timing accuracy, and attitude stability requirements. All of these factors directly impact the cost and flexibility of hosting such a sensor on a geosynchronous communication satellite. By choosing a relatively light weight, low power consumption sensor which requires a small amount of bandwidth to transmit its data, the cost of hosting the sensor is kept to a minimum. Once the type of sensor or sensors is identified, the next step is to identify idea geosynchronous locations for the "hosted" sensors. Once these locations are identified, then one would identify a potential host which needs to be replaced within the desired timeframe. Once the host is identified, then the satellite owner / operator should be approached about hosting a "neighborhood" watch sensor aboard their spacecraft. Commercial satellites are routinely replaced based on age, lack of available station keeping fuel or to allow a service provider to upgrade its capabilities. Each commercial communication satellite operator maintains a plan of replacing spacecraft. Between the two largest commercial SATCOM providers, INTELSAT and SES, six to eight spacecraft will be replaced each year (100 plus spacecraft with 15 year average lifetimes). The satellites are usually procured, designed, built, launched and operational within 36 months. In order for the US Government to adapt to this timeline, a sensor specification would need to be established as well as a sensor procurement pipeline. The sensors would then be provided to the satellite bus manufacturer for integration onto the bus. The spacecraft would then be launched and operated by the commercial SATCOM operator for the life of the spacecraft. Based on this approach, it is highly conceivable that a complete geosynchronous "neighborhood" watch program could be completed within 48 months of initiation.

Deaver, T.

197

AeroTCP: A Splitting Transport Protocol for an IP-based Satellite Network Supporting Aeronautical Communications  

Microsoft Academic Search

The IP-based Broadband Aeronautical Satellite Network will provide numerous new applications and services for both airspace system operations and passenger communications. However, the performance of data communications protocols and applications over such systems is dramatically degraded, especially the Internet TCP\\/IP protocol suite. In this paper, we propose a new transport protocols for satellite network supporting Internet and data services. Based

Yadong Shang; Michael Hadjitheodosiou; John Baras

198

Research on telescope array for inter-satellites laser communication  

Microsoft Academic Search

Recent years have seen an explosive increase in the application of inter-satellites laser communication system. Considerations make phased arrays an attractive target for optical communication applications. This paper proposes a novel telescope array for inter-satellites laser communication and investigates phased telescope arrays to be employed in receive terminals of free-space laser inter-satellites communication links. Potential advantages over single monolithic telescopes

Li Zhou; Chuanhua Wen

2006-01-01

199

Land vehicle antennas for satellite mobile communications  

NASA Technical Reports Server (NTRS)

Antenna designs applicable to future satellite mobile vehicle communications are examined. Microstrip disk, quadrifilar helix, cylindrical microstrip, and inverted V and U crossed-dipole low gain antennas (3-5 dBic) that provide omnidirectional coverage are described. Diagrams of medium gain antenna (9-12 dBic) concepts are presented; the antennas are classified into three types: (1) electronically steered with digital phase shifters; (2) electronically switched with switchable power divider/combiner; and (3) mechanically steered with motor. The operating characteristics of a conformal antenna with electronic beam steering and a nonconformal design with mechanical steering are evaluated with respect to isolation levels in a multiple satellite system. Vehicle antenna pointing systems and antenna system costs are investigated.

Haddad, H. A.; Paschen, D.; Pieper, B. V.

1985-01-01

200

Satellite Communication in the Internet: Its history and the Technology  

Microsoft Academic Search

This paper describes the history of satellite communication technology used on the Internet. Satellite links have been used on the Internet since the 1970s. In the early stages of the Internet, satellite links were used to connect one node to another. It was called a point-to-point connection. Several communication techniques and network topologies have been developed and deployed. This paper

Jun Takei; Jun Murai

2003-01-01

201

Multifunction personal and mobile SMM antenna for satellite communications systems  

Microsoft Academic Search

There are a number of personal and mobile communications systems based on the use of microwave links relayed by Earth-orbiting satellites between small, low-cost Earth terminals using antennas of low directivity and broad beam aiming at the appropriate satellites. These satellite communications systems are now either deployed or in various stages of development and planning. For example, there are the

J. J. H. Wang; J. K. Tillery

1997-01-01

202

Direct broadcast satellite service by direct broadcast satellite corporation  

Microsoft Academic Search

It is noted that common carrier operation implies the offer to transmit television programs or any other information in electronic form for any customer at a rate posted in a tariff recorded at the FCC and applied without discrimination. The satellite system developed must be flexible enough to provide virtually any transmision service its customers may decide to offer at

W. L. Pritchard; H. W. Radin

1984-01-01

203

A digitally implemented communications experiment utilizing the communications technology satellite, Hermes  

NASA Technical Reports Server (NTRS)

Developments which will reduce the costs associated with the distribution of satellite services are considered with emphasis on digital communication link implementation. A digitally implemented communications experiment (DICE) which demonstrates the flexibility and efficiency of digital transmission of television video and audio, telephone voice, and high-bit-rate data is described. The utilization of the DICE system in a full duplex teleconferencing mode is addressed. Demonstration teleconferencing results obtained during the conduct of two sessions of the 7th AIAA Communication Satellite Systems Conference are discussed. Finally, the results of link characterization tests conducted to determine (1) relationships between the Hermes channel 1 EIRP and DICE model performance and (2) channel spacing criteria for acceptable multichannel operation, are presented.

Jackson, H. D.; Fiala, J.

1980-01-01

204

Satellite Communications with NRAO Green Bank Antennas  

NASA Astrophysics Data System (ADS)

The National Radio Astronomy Observatory's Green Bank facility has several medium and large antennas that are available for satellite communications. The 100 meter Robert C. Byrd Green Bank Telescope (GBT), the largest and most sensitive antenna on site, is capable of receiving signals at frequencies as high as 86 GHz. In addition to the GBT are the fully operational 43 meter, 20 meter, and 13.7 meter antennas, and three mothballed 26 meter antennas. A transmitter could be fitted to any of these antennas for spacecraft uplinks. We discuss the characteristics of these antennas and possible operational models for future planetary science mission support.

Ford, John M.; Ford, H. Alyson; Watts, Galen

2014-11-01

205

In-Space Internet-Based Communications for Space Science Platforms Using Commercial Satellite Networks  

NASA Technical Reports Server (NTRS)

The continuing technological advances in satellite communications and global networking have resulted in commercial systems that now can potentially provide capabilities for communications with space-based science platforms. This reduces the need for expensive government owned communications infrastructures to support space science missions while simultaneously making available better service to the end users. An interactive, high data rate Internet type connection through commercial space communications networks would enable authorized researchers anywhere to control space-based experiments in near real time and obtain experimental results immediately. A space based communications network architecture consisting of satellite constellations connecting orbiting space science platforms to ground users can be developed to provide this service. The unresolved technical issues presented by this scenario are the subject of research at NASA's Glenn Research Center in Cleveland, Ohio. Assessment of network architectures, identification of required new or improved technologies, and investigation of data communications protocols are being performed through testbed and satellite experiments and laboratory simulations.

Kerczewski, Robert J.; Bhasin, Kul B.; Fabian, Theodore P.; Griner, James H.; Kachmar, Brian A.; Richard, Alan M.

1999-01-01

206

The Atlas family - Evolving and growing to meet communications satellite needs  

Microsoft Academic Search

The evolution of the Atlas family to meet the changing needs of the communication satellite community is discussed. Attention is given to Atlas enhancements and how they can be used to improve launch service cost effectiveness on current and future satellite designs through the decade. The December 1991 launch of the first Atlas II demonstrated the mission design flexibility and

D. R. Dunbar; R. C. Waterman; R. C. White; M. W. Henley

1992-01-01

207

The northern Utah satellite (NUSAT) communications link  

NASA Technical Reports Server (NTRS)

During the planning stages of the NUSAT satellite, an obvious issue to be discussed was the method of communications to be used. The frequencies would have to be high enough to pass through the atmosphere relatively unattenuated but low enough that antennas and transmission lines would not be so critical in length and properties that unexperienced students would have difficulty with handling them. The frequencies of 450.000 MHz and 137.900 MHz were decided upon and applied for licensing. Representatives of the amateur radio satellite organization, AMSAT, were contacted for ideas. This organization seems to favor AM types of emissions such as CW to control their OSCAR series of satellites and also the current Phase 3 unit. NUSAT personnel felt, however, that there would be merit in the improved signal to noise ratio usually obtained in an FM mode. Doppler shift of the transmitted information on the NUSAT also had to be considered. The final decision was to use Audio Frequency Shift Keying (ASKF) modulated on an FM carrier. In this mode audio tones used would not shift frequency with Doppler.

Barrett, L.

1986-01-01

208

Presentations of the Ninth Advanced Communications Technology Satellite Propagation Studies Workshop (APSW IX)  

NASA Technical Reports Server (NTRS)

The Advanced Communications Technology Satellite Propagation Studies Workshop (APSW) is convened each year to present the results of the ACTS Propagation Campaign. Representatives from the satellite communications (satcom) industry, academia, and government are invited to APSW for discussions and exchange of information. The ACTS Propagation campaign is completing three years of Ka-Band data collection at seven sites in North America. Through this effort, NASA is making a major contribution to growth of satcom services by providing timely propagation data and models for predicting the performance of Ka-Band satellite communications systems.

Golshan, Nasser (Editor)

1997-01-01

209

Two-way time transfer via communication satellites  

Microsoft Academic Search

The history of two-way satellite time transfer is provided and developments in satellite communications technology conducive to this time transfer technique are briefly reviewed. The difference between one-way and two-way satellite time transfer is explained, and the advantages and disadvantages of the two-way method are pointed out. The theory of the two-way technique using geostationary communication satellites is presented showing

Dieter Kirchner

1991-01-01

210

Ka-band aeronautical satellite communications experiments using COMETS  

Microsoft Academic Search

This paper describes the results of evaluation tests of an aeronautical satellite communications experiments system in the Ka-band using Japan's communications and broadcasting engineering test satellite (COMETS). An active phased-array antenna with an open-loop satellite tracking capability operating in the Ka-band was installed just behind the passenger window of an airplane to receive a satellite signal. The propagation measurements showed

Amane Miura; Shinichi Yamamoto; Huan-Bang Li; Masato Tanaka; Hiromitsu Wakana

2002-01-01

211

Communicating Services Brands' Values Internally and Externally  

Microsoft Academic Search

This paper explores the ways that services brand values are communicated to both staff and customers. Values are communicated to employees via overt internal communications, the ripple effect, senior management example\\/involvement, HR activities and external communications. A number of failure factors which could hinder the communication of values to employees are identified. For consumers, values are communicated via their holistic

Leslie De Chernatony; Susan Cottam; Susan Segal-Horn

2006-01-01

212

Satellite constellations summary, analysis and design for China mobile satellite communication  

Microsoft Academic Search

We proposed and studied a number of methods of satellite constellation design for regional mobile satellite communication (MSC), and obtained some useful results for China's regional MSC. These methods of constellation design can also be applied for other regional mobile satellite communication systems

Duan Shaohua; Zhang Zhongzhao; Zhang Naitong

1998-01-01

213

Denial of service prevention in satellite networks  

Microsoft Academic Search

Networks integrating satellite shared access, such as DVB-S\\/RCS, are particularly exposed to denial of service (DoS) attacks through which a satellite terminal can maliciously use the Network Control Center (NCC) resources by submitting a high number of bogus requests. Anti-clogging techniques used in terrestrial mesh networks to thwart DoS attacks fall short of solving DoS problems in the case of

M. Onen; R. Molva

2004-01-01

214

ESA personal communications and digital audio broadcasting systems based on non-geostationary satellites  

NASA Technical Reports Server (NTRS)

Personal Communications and Digital Audio Broadcasting are two new services that the European Space Agency (ESA) is investigating for future European and Global Mobile Satellite systems. ESA is active in promoting these services in their various mission options including non-geostationary and geostationary satellite systems. A Medium Altitude Global Satellite System (MAGSS) for global personal communications at L and S-band, and a Multiregional Highly inclined Elliptical Orbit (M-HEO) system for multiregional digital audio broadcasting at L-band are described. Both systems are being investigated by ESA in the context of future programs, such as Archimedes, which are intended to demonstrate the new services and to develop the technology for future non-geostationary mobile communication and broadcasting satellites.

Logalbo, P.; Benedicto, J.; Viola, R.

1993-01-01

215

a System Design and Analysis for Satellite Communication Link  

NASA Astrophysics Data System (ADS)

A satellite RF communication link is analyzed based on a simple fundamental equations by systematic approach in this paper. The number of variables related to a design and analysis of satellite RF link is often a dozen or more, thus it is a tedious and time-consuming task. With the given input data, the important parameters are calculated step by step and three communication characteristics such as communication channel capacity, carrier-to-noise ratio (CNR) at the satellite and ground station are analyzed. It gives very useful information to the system engineers for designing and analyzing the overall satellite communication system in the conceptual design phase.

Chung, Tae-Jin; Eun, Jong-Won

2000-12-01

216

NASA to launch second business communications satellite  

NASA Technical Reports Server (NTRS)

The two stage Delta 3910 launch vehicle was chosen to place the second small business satellite (SBS-B) into a transfer orbit with an apogee of 36,619 kilometers and a perigee of 167 km, at an inclination of 27.7 degrees to Earth's equator. The firing and separation sequence and the inertial guidance system are described as well as the payload assist module. Facilities and services for tracking and control by NASA, COMSAT, Intelsat, and SBS are outlined and prelaunch operations are summarized.

1981-01-01

217

Payload system tradeoffs for mobile communications satellites  

NASA Technical Reports Server (NTRS)

System level trade-offs carried out during Mobile Satellite (M-SAT) design activities are described. These trade-offs relate to the use of low level beam forming, flexible power and spectrum distribution, and selection of the number of beams to cover the service area. It is shown that antenna performance can be improved by sharing horns between beams using a low level beam forming network (BFN). Additionally, greatly increased power utilization is possible using a hybrid matrix concept to share power between beams.

Moody, H. J.

1990-01-01

218

Telematic services via satellite in Europe  

NASA Astrophysics Data System (ADS)

Telematics in Europe is intended to provide service through five satellites: Eutelsat, Telecom 1, Unisat, DFS, and Italsat. A 'Central Europe' zone will have coverage from the five satellites simultaneously; Eutelsat will be at the hub of the network and will have the largest coverage of all. Two to five transponders per satellite are to be used for telematic special services on the 12.5-12.75 GHz down-link band; Italsat will use a 20 GHz down-link. The ground segment will use several hundred small 3.5 m dish antennas and SCPC or 25-60 Mb/s TDMA equipment. Among many services, telematics will include videoconferences, computer-to-computer data transfer, high speed facsimile, and transatlantic digital business. Although all five networks will operate independently, future interconnection among them will allow efficiency improvements.

Goumy, C.; Golden, E.

1984-03-01

219

Faster than fiber: Advantages and challenges of LEO communications satellite systems  

NASA Astrophysics Data System (ADS)

Low Earth Orbit (LEO) communications satellite systems are emerging as attractive alternatives to the Geostationary Earth Orbit (GEO) systems. GEO satellites have largely dominated the commercial and government communications satellite systems for telecommunications services since the early 1960's. A principal driver behind the move to LEO satellites is the competition to long propagation delay geostationary orbit satellite systems created by rapid expansion of short propagation delay terrestrial land and undersea fiber optic cable links for national and global connectivity. Communication paths over LEO satellites can have shorter propagation delay than terrestrial fiber. This is because the speed of electromagnetic wave propagation via LEO satellites is 50% greater than that of light in fiber optic cable. This fact eliminates the long propagation delay property that has become synonymous with GEO communications satellite systems. Other drivers are the use of small portable and hand-held earth terminals and the promise of lower launch cost of small satellites to low earth orbits. The paper expands on the properties that promise to make LEO communications satellite systems the choice of the future.

Campanella, S. Joseph; Kirkwood, Timothy J.

1995-01-01

220

A study and experiment plan for digital mobile communication via satellite  

Microsoft Academic Search

The viability of mobile communications is examined within the context of a frequency division multiple access, single channel per carrier satellite system emphasizing digital techniques to serve a large population of users. The intent is to provide the mobile users with a grade of service consistant with the requirements for remote, rural (perhaps emergency) voice communications, but which approaches toll

J. J. Jones; E. J. Craighill; R. G. Evans; A. D. Vincze; N. N. Tom

1978-01-01

221

A framework for implementing data services in multi-service mobile satellite systems  

NASA Technical Reports Server (NTRS)

Mobile satellite systems being planned for introduction in the early 1990s are expected to be invariably of the multi-service type. Mobile Telephone Service (MTS), Mobile Radio Service (MRS), and Mobile Data Service (MDS) are the major classifications used to categorize the many user applications to be supported. The MTS and MRS services encompass circuit-switched voice communication applications, and may be efficiently implemented using a centralized Demand-Assigned Multiple Access (DAMA) scheme. Applications under the MDS category are, on the other hand, message-oriented and expected to vary widely in characteristics; from simplex mode short messaging applications to long duration, full-duplex interactive data communication and large file transfer applications. For some applications under this service category, the conventional circuit-based DAMA scheme may prove highly inefficient due to the long time required to set up and establish communication links relative to the actual message transmission time. It is proposed that by defining a set of basic bearer services to be supported in MDS and optimizing their transmission and access schemes independent of the MTS and MRS services, the MDS applications can be more efficiently integrated into the multi-service design of mobile satellite systems.

Ali, Mohammed O.; Leung, Victor C. M.; Spolsky, Andrew I.

1988-01-01

222

A digital simulation of message traffic for natural disaster warning communications satellite  

NASA Technical Reports Server (NTRS)

Various types of weather communications are required to alert industries and the general public about the impending occurrence of tornados, hurricanes, snowstorms, floods, etc. A natural disaster warning satellite system has been proposed for meeting the communications requirements of the National Oceanic and Atmospheric Administration. Message traffic for a communications satellite was simulated with a digital computer in order to determine the number of communications channels to meet system requirements. Poisson inputs are used for arrivals and an exponential distribution is used for service.

Hein, G. F.; Stevenson, S. M.

1972-01-01

223

Communications satellite systems operations with the space station. Volume 3: Supplementary technical report  

NASA Technical Reports Server (NTRS)

The NASA space station has the potential to provide significant economic benefits to commercial communications satellite operators. The initial reports qunatified the benefits of space-based activities and assessed the impacts on the satellite design and the space station. Results are given for the following additional tasks: quantify the value of satellite retrievability operations and define its operational aspects; evaluate the use of expendable launch vehicles for transportation of satellites from the Earth to the space station; and quantify the economic value of modular satellites that are assembled and serviced in space.

Price, K. M.; Russell, P.; Weyandt, C.

1988-01-01

224

Satellite Communications Technology Database. Part 2  

NASA Technical Reports Server (NTRS)

The Satellite Communications Technology Database is a compilation of data on state-of-the-art Ka-band technologies current as of January 2000. Most U.S. organizations have not published much of their Ka-band technology data, and so the great majority of this data is drawn largely from Japanese, European, and Canadian publications and Web sites. The data covers antennas, high power amplifiers, low noise amplifiers, MMIC devices, microwave/IF switch matrices, SAW devices, ASIC devices, power and data storage. The data herein is raw, and is often presented simply as the download of a table or figure from a site, showing specified technical characteristics, with no further explanation.

2001-01-01

225

Mass and power modeling of communication satellites  

NASA Technical Reports Server (NTRS)

Analytic estimating relationships for the mass and power requirements for major satellite subsystems are described. The model for each subsystem is keyed to the performance drivers and system requirements that influence their selection and use. Guidelines are also given for choosing among alternative technologies which accounts for other significant variables such as cost, risk, schedule, operations, heritage, and life requirements. These models are intended for application to first order systems analyses, where resources do not warrant detailed development of a communications system scenario. Given this ground rule, the models are simplified to 'smoothed' representation of reality. Therefore, the user is cautioned that cost, schedule, and risk may be significantly impacted where interpolations are sufficiently different from existing hardware as to warrant development of new devices.

Price, Kent M.; Pidgeon, David; Tsao, Alex

1991-01-01

226

Capacity as a consideration for providing aeronautical mobile satellite air traffic services in the US domestic airspace  

Microsoft Academic Search

International standards are being developed by the International Civil Aviation Organization for an aeronautical mobile-satellite service (AMSS). Moreover, the American Mobile Satellite Corporation (AMSC) is constructing a satellite communications that could provide this service in US domestic airspace. The author describes a preliminary analysis of the capacity (number of aircraft) that could be handled by the first-generation AMSC system in

C. A. Shively

1992-01-01

227

ANNUAL REPORT NOAA SATELLITE AND INFORMATION SERVICE  

E-print Network

MISSION To understand and predict changes in Earth's climate, weather, oceans, and coasts; share, and apply this understanding to issues such as the causes and consequences of climate change; the physical The NOAA Satellite and Information Service: Who We Are, What We Do 8 Goal 1: Climate Adaptation

228

The Automated Digital Network System (ADNS) Interface to Transformational Satellite Communications System (TSAT)  

Microsoft Academic Search

The U. S. Department of Defense (DoD) is in the initial phase of building the Global Information Grid (GIG), a private secure internetwork connecting a number of its joint and service-specific IP networks. Two of these networks are the Automated Digital Network System (ADNS) and the Transformational Satellite Communications System (TSAT). ADNS provides network services and entry into the Defense

Joanna N. Ptasinski; Yenchi Congtang

2007-01-01

229

Rain Fade Compensation Alternatives for Ka Band Communication Satellites  

NASA Technical Reports Server (NTRS)

Future satellite communications systems operating in Ka-band frequency band are subject to degradation produced by the troposphere which is much more severe than those found at lower frequency bands. These impairments include signal absorption by rain, clouds and gases, and amplitude scintillation's arising from refractive index irregularities. For example, rain attenuation at 20 GHz is almost three times that at 11 GHz. Although some of these impairments can be overcome by oversizing the ground station antennas and high power amplifiers, the current trend is using small (less than 20 inches apertures), low-cost ground stations (less than $1000) that can be easily deployed at user premises. As a consequence, most Ka-band systems are expected to employ different forms of fade mitigation that can be implemented relatively easily and at modest cost. The rain fade mitigation approaches are defined by three types of Ka-band communications systems - a low service rate (less than 1.5 Mb/s), a moderate service rate (1.5 to 6 Mb/s) system and a high service rate (greater than 43 Mb/s) system. The ACTS VSAT network, which includes an adaptive rain fade technique, is an example of a moderate service rate.

Acosta, Roberto J.

1997-01-01

230

Emerging commercial opportunities based on combined communication navigation services  

NASA Astrophysics Data System (ADS)

Cost reduction pressure on companies and increasing regulatory and legislative demand together with rapid technological progress in space-based communication and navigation are opening up new and exciting commercial opportunities. In this framework, a novel service for maritime applications is presented using a two-way messaging system and the global navigation satellite system (GNSS). The system implements an end-to-end solution for asset tracking and fleet management, positioning and tracing, messaging and security for all types of sea-going vessels. The service applies a vessel-based terminal hosting a GNSS receiver which transmits the navigation status together with messages to a Service Center with a flexible return-link capability. A hybrid space segment is considered comprising the Inmarsat constellation of geostationary communications satellites augmented by two highly inclined low earth orbit satellites for truly global services. Services will be offered to commercial enterprises such as fishing companies as well as public entities such as National Coast Guards. A detailed market analysis has been performed to assess these markets and to determine their penetration. Commercial viability has been proven for business models purely based on Inmarsat and a hybrid space segment using Inmarsat and dedicated micro-satellites. Both cases represent viable businesses in the range of MEUR 100 p.a. Although tailored to a specific market, the approach can be extended to other commercial opportunities requiring space-based communication-navigation services.

Gill, Eberhard; Fox, Brian M.; Kreisel, Joerg

2006-07-01

231

A robust signalling system for land mobile satellite services  

NASA Technical Reports Server (NTRS)

Presented here is a signalling system optimized to ensure expedient call set-up for satellite telephony services in a land mobile environment. In a land mobile environment, the satellite to mobile link is subject to impairments from multipath and shadowing phenomena, which result in signal amplitude and phase variations. Multipath, caused by signal scattering and reflections, results in sufficient link margin to compensate for these variations. Direct signal attenuation caused by shadowing due to buildings and vegetation may result in attenuation values in excess of 10 dB and commonly up to 20 dB. It is not practical to provide a link with sufficient margin to enable communication when the signal is blocked. When a moving vehicle passes these obstacles, the link will experience rapid changes in signal strength due to shadowing. Using statistical models of attenuation as a function of distance travelled, a communication strategy has been defined for the land mobile environment.

Irish, Dale; Shmith, Gary; Hart, Nick; Wines, Marie

1989-01-01

232

PLANNING AND DEVELOPMENT OF INDONESIA'S DOMESTIC COMMUNICATIONS SATELLITE SYSTEM PALAPA  

Microsoft Academic Search

On that thirty-first anniversary of Indonesian independence, the country's PALAPA domestic communication satellite system was inaugurated by President Suharto. This occasion made Indonesia the first developing country to acquire its own domestic satellite. This article aims to trace back the decision making process that led Indonesia to acquire its domestic satellite system, far ahead of other developing countries, i.e., six

Marwah Daud Ibrahim

233

Suitability of ANSI standards for quantifying communication satellite system performance  

NASA Technical Reports Server (NTRS)

A study on the application of American National Standards X3.102 and X3.141 to various classes of communication satellite systems from the simple analog bent-pipe to NASA's Advanced Communications Technology Satellite (ACTS) is discussed. These standards are proposed as means for quantifying the end-to-end communication system performance of communication satellite systems. An introductory overview of the two standards are given followed by a review of the characteristics, applications, and advantages of using X3.102 and X3.141 to quantify with a description of the application of these standards to ACTS.

Cass, Robert D.

1988-01-01

234

Controlling satellite communication system unwanted emissions in congested RF spectrum  

NASA Astrophysics Data System (ADS)

The International Telecommunication Union (ITU), a United Nations (UN) agency, is the agency that, under an international treaty, sets radio spectrum usage regulations among member nations. Within the United States of America (USA), the organization that sets regulations, coordinates an application for use, and provides authorization for federal government/agency use of the radio frequency (RF) spectrum is the National Telecommunications and Information Administration (NTIA). In this regard, the NTIA defines which RF spectrum is available for federal government use in the USA, and how it is to be used. The NTIA is a component of the United States (U.S.) Department of Commerce of the federal government. The significance of ITU regulations is that ITU approval is required for U.S. federal government/agency permission to use the RF spectrum outside of U.S. boundaries. All member nations have signed a treaty to do so. U.S. federal regulations for federal use of the RF spectrum are found in the Manual of Regulations and Procedures for Federal Radio Frequency Management, and extracts of the manual are found in what is known as the Table of Frequency Allocations. Nonfederal government and private sector use of the RF spectrum within the U.S. is regulated by the Federal Communications Commission (FCC). There is a need to control "unwanted emissions" (defined to include out-of-band emissions, which are those immediately adjacent to the necessary and allocated bandwidth, plus spurious emissions) to preclude interference to all other authorized users. This paper discusses the causes, effects, and mitigation of unwanted RF emissions to systems in adjacent spectra. Digital modulations are widely used in today's satellite communications. Commercial communications sector standards are covered for the most part worldwide by Digital Video Broadcast - Satellite (DVB-S) and digital satellite news gathering (DSNG) evolutions and the second generation of DVB-S (DVB-S2) standard, developed by the European Telecommunications Standards Institute (ETSI). In the USA, the Advanced Television Systems Committee (ATSC) has adopted Europe's DVB-S and DVB-S2 standards for satellite digital transmission. With today's digital modulations, RF spectral side lobes can extend out many times the modulating frequency on either side of the carrier at excessive power levels unless filtered. Higher-order digital modulations include quadrature phase shift keying (QPSK), 8 PSK (8-ary phase shift keying), 16 APSK (also called 12-4 APSK (amplitude phase shift keying)), and 16 QAM (quadrature amplitude modulation); they are key for higher spectrum efficiency to enable higher data rate transmissions in limited available bandwidths. Nonlinear high-power amplifiers (HPAs) can regenerate frequency spectral side lobes on input-filtered digital modulations. The paper discusses technologies and techniques for controlling these spectral side lobes, such as the use of square root raised cosine (SRRC) filtering before or during the modulation process, HPA output power back-off (OPBO), and RF filters after the HPA. Spectral mask specifications are a common method of the NTIA and ITU to define spectral occupancy power limits. They are intended to reduce interference among RF spectrum users by limiting excessive radiation at frequencies beyond the regulatory allocated bandwidth.The focus here is on the communication systems of U.S. government satellites used for space research, space operations, Earth exploration satellite services (EESS), meteorological satellite services (METSATS), and other government services. The 8025 to 8400 megahertz (MHz) X band can be used to illustrate the "unwanted emissions" issue. 8025 to 8400 MHz abuts the 8400 to 8450 MHz band allocated by the NTIA and ITU to space research for space-to-Earth transmissions such as receiving very weak Deep Space Network signals. The views and ideas expressed in this paper are those of the authors and do not necessarily reflect those of The Aerospace Corporation or The National Oceanic and Atmosphe

Olsen, Donald; Heymann, Roger

2007-09-01

235

Personal communications services: Improving theater deployable communications for the 21st century  

NASA Astrophysics Data System (ADS)

Personal Communications Services (PCS) may be the key ingredient for vastly improved military communications capabilities at the turn of the century. The Federal Communications Commission (FCC) defines PCS as a family of mobile or portable radio communications services which could provide services to individuals and businesses and be integrated with a variety of competing networks ... the primary focus of PCS will be to meet communications requirements of people on the move. Today's generation of Theater Deployable Communications, which provides joint tactical communications to deployed forces, is the Tri-Service Tactical Communications (TRI-TAC) system. A description of TRITAC's family of equipment, network topology, typical employment, and critical limitations is presented in this thesis. Five commercial Mobile Satellite Services (MSS) are described as viable candidates for augmenting existing communications systems. Cellular design principles such as frequency reuse, cell splitting, channel access methods, and propagation factors are also addressed. Finally, a framework for comparison of the candidate MSS systems is proposed as a baseline for further studies into the most beneficial implementation of PCS into theater deployable communications systems for the future.

Cournoyer, Ronald C., Jr.

1994-06-01

236

Mobile communications satellite antenna flight experiment definition  

NASA Astrophysics Data System (ADS)

There are classes of application that collectively require a variety of different types of large-aperture space antennas. Fortunately, there are a number of different deployable antenna concepts that have tremendous potential for such applications. However, these concepts vary in maturity from flight-proven designs to extremely innovative configuration definitions. But these promising concepts lack sufficient demonstrations of maturity to be seriously considered in the large size range for immediate application. The reason for this situation is an extremely limited space flight data base in addition to the technical limitations and great costs associated with meaningful ground testing of large, flexible, precision space structures. The user community of such structures, especially the commercial organizations interested in providing a Mobile Communications Satellite (MSAT) on a profit-making basis, will require significant demonstrations of technology readiness prior to application commitment. Such demonstrations will probably be based on a combination of extensive ground testing and subsequent space flight experiments. The Communications Division of the National Aeronautics and Space Administration (NASA) Office of Space Science and Applications sponsored a study at the Jet Propulsion Laboratory (JPL) to determine the technical feasibility and cost of a Shuttle-based flight experiment specifically intended for the MSAT commercial user community. The experiment will include demonstrations of technology in the areas of radio frequency (RF), sensing and control, and structures. This paper summarizes the results of the structural subsystem study. These results include experiment objective and technical approach, experiment structural description, structure/environment interactions, structural characterization, thermal characterization, structural measurement system, and experiment functional description.

Freeland, Robert E.

237

Aeronautical Mobile Satellite Service (AMSS) capacity analysis and protocol performance simulation results  

Microsoft Academic Search

The Federal Aviation Administration (FAA) is supporting the development of standards for the use of satellite communications in aviation. As part of this support, the FAA has conducted an analysis and simulation of the Aeronautical Mobile Satellite Service (AMSS) to determine the capacity of this system to meet data requirements and to determine the message transit delay of the system

Thomas F. Dehel

1992-01-01

238

15 CFR 950.8 - Satellite Data Services Division (SDSD).  

Code of Federal Regulations, 2011 CFR

...2011-01-01 2011-01-01 false Satellite Data Services Division (SDSD). 950.8 Section...COMMERCE GENERAL REGULATIONS OF THE ENVIRONMENTAL DATA SERVICE ENVIRONMENTAL DATA AND INFORMATION § 950.8 Satellite Data...

2011-01-01

239

15 CFR 950.8 - Satellite Data Services Division (SDSD).  

Code of Federal Regulations, 2012 CFR

...2012-01-01 2012-01-01 false Satellite Data Services Division (SDSD). 950.8 Section...COMMERCE GENERAL REGULATIONS OF THE ENVIRONMENTAL DATA SERVICE ENVIRONMENTAL DATA AND INFORMATION § 950.8 Satellite Data...

2012-01-01

240

15 CFR 950.8 - Satellite Data Services Division (SDSD).  

Code of Federal Regulations, 2010 CFR

...2010-01-01 2010-01-01 false Satellite Data Services Division (SDSD). 950.8 Section...COMMERCE GENERAL REGULATIONS OF THE ENVIRONMENTAL DATA SERVICE ENVIRONMENTAL DATA AND INFORMATION § 950.8 Satellite Data...

2010-01-01

241

15 CFR 950.8 - Satellite Data Services Division (SDSD).  

...2014-01-01 2014-01-01 false Satellite Data Services Division (SDSD). 950.8 Section...COMMERCE GENERAL REGULATIONS OF THE ENVIRONMENTAL DATA SERVICE ENVIRONMENTAL DATA AND INFORMATION § 950.8 Satellite Data...

2014-01-01

242

A Hybrid Satellite-Terrestrial Approach to Aeronautical Communication Networks  

NASA Technical Reports Server (NTRS)

Rapid growth in air travel has been projected to continue for the foreseeable future. To maintain a safe and efficient national and global aviation system, significant advances in communications systems supporting aviation are required. Satellites will increasingly play a critical role in the aeronautical communications network. At the same time, current ground-based communications links, primarily very high frequency (VHF), will continue to be employed due to cost advantages and legacy issues. Hence a hybrid satellite-terrestrial network, or group of networks, will emerge. The increased complexity of future aeronautical communications networks dictates that system-level modeling be employed to obtain an optimal system fulfilling a majority of user needs. The NASA Glenn Research Center is investigating the current and potential future state of aeronautical communications, and is developing a simulation and modeling program to research future communications architectures for national and global aeronautical needs. This paper describes the primary requirements, the current infrastructure, and emerging trends of aeronautical communications, including a growing role for satellite communications. The need for a hybrid communications system architecture approach including both satellite and ground-based communications links is explained. Future aeronautical communication network topologies and key issues in simulation and modeling of future aeronautical communications systems are described.

Kerczewski, Robert J.; Chomos, Gerald J.; Griner, James H.; Mainger, Steven W.; Martzaklis, Konstantinos S.; Kachmar, Brian A.

2000-01-01

243

Inter-satellite communications using laser based optical links  

Microsoft Academic Search

Laser Communications offer a viable alternative to established RF communications for inter-satellite links and other applications where high performance links are a necessity. High data rate, small antenna size, narrow beam divergence, and a narrow field of view are characteristics of laser communications that offer a number of potential advantages for system design. This paper will focus on the requirements

Allen S. Panahi; Alex A. Kazemi

2007-01-01

244

Cockpit weather graphics using mobile satellite communications  

NASA Astrophysics Data System (ADS)

Many new companies are pushing state-of-the-art technology to bring a revolution in the cockpits of General Aviation (GA) aircraft. The vision, according to Dr. Bruce Holmes - the Assistant Director for Aeronautics at National Aeronautics and Space Administration's (NASA) Langley Research Center, is to provide such an advanced flight control system that the motor and cognitive skills you use to drive a car would be very similar to the ones you would use to fly an airplane. We at ViGYAN, Inc., are currently developing a system called the Pilot Weather Advisor (PWxA), which would be a part of such an advanced technology flight management system. The PWxA provides graphical depictions of weather information in the cockpit of aircraft in near real-time, through the use of broadcast satellite communications. The purpose of this system is to improve the safety and utility of GA aircraft operations. Considerable effort is being extended for research in the design of graphical weather systems, notably the works of Scanlon and Dash. The concept of providing pilots with graphical depictions of weather conditions, overlaid on geographical and navigational maps, is extremely powerful.

Seth, Shashi

245

The Eutelsat II satellites - Europe's seeds in communication and TV distribution game  

NASA Astrophysics Data System (ADS)

The Eutelsat satellite will furnish Ku-band communication and TV-distribution services with 16 active channels that are simultaneously accessible to users throughout Europe. This Ariane IV-compatible satellite possesses reconfigurable antenna feed networks that permit zoom operation on all 16 channels, and is fully operational during eclipse. Only two antennas will be used for all communications-transmit and -receive stations, greatly simplifying repeater reconfiguration. The use of 8/12 amplifier ring redundancy during and beyond the projected 7-year service life will ensure reliability.

Burgio, C.; Soula, J. L.; Dumesnil, J. J.

1987-10-01

246

Accommodation of Broadcast Satellite (Sound) and Mobile Satellite Services in the 2300-2450 MHZ Band.  

National Technical Information Service (NTIS)

This report provides a feasibility assessment of accommodating the Broadcast Satellite (Sound) Service and a Mobile Satellite Service uplink in the 2300-2450 MHz range. The assessment is based upon measurements by the Institute for Telecommunication Scien...

A. A. Filippi, B. J. Ramsey, F. H. Sanders, K. B. Nebbia, R. L. Hinkle

1992-01-01

247

77 FR 48584 - Tenth Meeting: RTCA Special Committee 222, Inmarsat Aeronautical Mobile Satellite (Route) Services  

Federal Register 2010, 2011, 2012, 2013

...Committee 222, Inmarsat Aeronautical Mobile Satellite (Route) Services AGENCY...Committee 222, Inmarsat Aeronautical Mobile Satellite (Route) Services...Committee 222, Inmarsat Aeronautical Mobile Satellite (Route) Services....

2012-08-14

248

77 FR 30046 - Ninth Meeting: RTCA Special Committee 222, Inmarsat Aeronautical Mobile Satellite (Route) Services  

Federal Register 2010, 2011, 2012, 2013

...Committee 222, Inmarsat Aeronautical Mobile Satellite (Route) Services AGENCY...Committee 222, Inmarsat Aeronautical Mobile Satellite (Route) Services...Committee 222, Inmarsat Aeronautical Mobile Satellite (Route) Services....

2012-05-21

249

75 FR 15770 - Fifth Meeting-Special Committee 222: Inmarsat Aeronautical Mobile Satellite (Route) Services  

Federal Register 2010, 2011, 2012, 2013

...Committee 222: Inmarsat Aeronautical Mobile Satellite (Route) Services AGENCY...Committee 222: Inmarsat Aeronautical Mobile Satellite (Route) Services meeting...Committee 222: Inmarsat Aeronautical Mobile Satellite (Route) Services....

2010-03-30

250

75 FR 39724 - Sixth Meeting-Special Committee 222: Inmarsat Aeronautical Mobile Satellite (Route) Services  

Federal Register 2010, 2011, 2012, 2013

...222: Inmarsat Aeronautical Mobile Satellite (Route) Services...222: Inmarsat Aeronautical Mobile Satellite (Route) Services...222: Inmarsat Aeronautical Mobile Satellite (Route) Services... Status of ATCt filter development activities (Inmarsat)....

2010-07-12

251

Inmarsat's worldwide mobile-satellite services - Today and tomorrow  

NASA Astrophysics Data System (ADS)

The status of existing Inmarsat mobile satellite services, new services under implementation for production in the near term, and also longer-term plans, including those for the hand-held satellite phone, are described. Attention is given to the evolution of the Inmarsat satellite system, smaller lower-cost terminals, and lower-cost voice services.

Singh, Jai P.

1993-01-01

252

Engineering calculations for communications satellite systems planning  

NASA Technical Reports Server (NTRS)

A procedure is described that was used to calculate minimum required satellite separations based on total link carrier to interference requirements. Also summarized are recent results with a switching algorithm for satellite synthesis problems. Analytic solution value bounds for two of the satellite synthesis models studied are described. Preliminary results from an empirical study of alternate mixed integer programming models for satellite synthesis are presented. Research plans for the near future are discussed.

Reilly, Charles H.; Walton, Eric K.; Kohnhorst, Paul

1987-01-01

253

The use of mobile satellite communication terminals  

NASA Astrophysics Data System (ADS)

The role of small portable terminals in military satellite systems is examined; the discussion embraces terminals with an antenna reflector diameter of seven meters or less. Emphasis is placed on the specification of MARMOSET (Marconi Mobile Satellite Earth Terminal). Also considered are ship-borne satellite terminals, the improved SCOT terminal, interoperability, reduced downlink power, and reliability and availability.

Law, P. A.

254

Satellite communication and navigation for mobile users  

NASA Technical Reports Server (NTRS)

Efforts made to utilize space technology for solving communication and navigation problems faced by mobile users in earth orientated situations are outlined. Applications include transoceanic airline communications, reliable long range ship-shore communications, emergency communications in regions with rough terrain, and military operations.

Bernstein, S. L.

1972-01-01

255

47 CFR 90.371 - Dedicated short range communications service.  

Code of Federal Regulations, 2010 CFR

...false Dedicated short range communications service. 90.371 Section...Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) ...for Dedicated Short-Range Communications Service (dsrcs) §...

2010-10-01

256

DMSK Receiver For Mobile/Satellite Service  

NASA Technical Reports Server (NTRS)

Receiver for 2.4-kbit/s differential minimum-shift keying (DMSK) and Gaussian minimum-shift keying(GMSK) suitable for communication between land-mobile stations via geostationary satellites. Operating on phase-shifted signal in 800-MHz band, in presence of fading and Doppler frequency shifts, receiver compact, makes efficient use of frequency spectrum, and wastes little power. Receiver design implemented in very-large-scale-integrated circuits. Basic DMSK receiver design relies on baseband rather than intermediate-frequency processing of in-phase and quadrature signal components because phase errors due to differential delays smaller at baseband.

Davarian, Faramaz; Simon, Marvin K.; Sumida, Joe T.

1989-01-01

257

Low Earth-orbit store-and-forward satellites in the amateur radio service  

Microsoft Academic Search

Several aspects of the most recently launched low-earth-orbit (LEO) store-and-forward satellites operating in the amateur satellite service are described. Included are a description of the satellites and their most interesting implementation details, with particular emphasis on the communications system; a description of the file server and broadcast protocol; a description of operation from the user's viewpoint; and some statistics characterizing

Robert J. Diersing; Greg Jones

1993-01-01

258

Technology programs and related policies - Impacts on communications satellite business ventures  

NASA Technical Reports Server (NTRS)

The DOMSAT II stochastic communication satellite business venture financial planning simulation model is described. The specification of business scenarios and the results of several analyses are presented. In particular, the impacts of NASA on-orbit propulsion and power technology programs are described. The effects of insurance rates and self-insurance and of the use of the Space Shuttle and Ariane transportation systems on a typical fixed satellite service business venture are discussed.

Greenberg, J. S.

1985-01-01

259

The 18/30 GHz fixed communications system service demand assessment. Volume 1: Executive summary  

NASA Technical Reports Server (NTRS)

The total demand for voice, video, and data communications services, and satellite transmission services at the 4/6 GHz, 12/14 GHz, and 18/30 GHz frequencies is discussed. Major study objectives, overall methodology, results, and general observations about a satellite systems market characteristics and trends are summarized.

Gabriszeski, T.; Reiner, P.; Rogers, J.; Terbo, W.

1979-01-01

260

Emerging communication technologies in emergency medical services  

Microsoft Academic Search

Advances in communication technologies are changing the face of emergency medical services (EMS). Two communication technologies in particular—cellular-enhanced 9-1-1 service and automatic crash notification (ACN)—will have a considerable impact on EMS. Although enhanced 9-1-1 service from land-line phones is now available in nearly every EMS system across the country, enhanced 9-1-1 service from cell phones currently does not exist. With

Richard C. Hunt

2002-01-01

261

Space-based laser systems for inter-satellite communications  

NASA Astrophysics Data System (ADS)

Space-based optical communications using satellites in low earth orbit (LEO) and Geo synchronous orbits (GEO) hold great promise for the proposed Internet in the Sky network of the future. Building high speed communications network using optical links in space has proven to be an extremely complicated task and many such schemes were tried without success in the past. However in the last few years, there has been impressive progress made to bring the concept of space based laser systems for inter-satellite communications to fruition in civilian and government-non classified projects. Laser Communications High data rate, small antenna size, narrow beam divergence, and a narrow field of view are characteristics of laser communications that offer a number of potential advantages for system design. Also discussed are the laser based optical inter-satellite communication equipment which enables large capacity communication, and the advantage of their systems. Laser-based communications offer a viable alternative to established RF communications for inter-satellite links and other applications where high performance links are a necessity.

Kazemi, Alex A.; Panahi, Allen

2012-06-01

262

Communication satellites for STS-5 being readied for loading  

NASA Technical Reports Server (NTRS)

Two commercial communication satellites scheduled for flight on STS-5 are pictured as they are being readied for loading into a special canister that will transport them to the launch pad. Telsat Canada's Anik C-3 (at bottom) is seen in its blanket covered cradle assemble. Satellite Business System's SBS-3 is at top. This photo was taken inside the vertical processing facility (VPF).

1982-01-01

263

Analysis of submarine cable and communication satellite systems reliabilities  

Microsoft Academic Search

The performance of AT&T's overseas message telephone circuits for the years 1970-1975 was the basis for ana analysis of the reliability of submarine cables and communication satellite systems. Data presented in 24 tables is devided into three categories: (1) over cable and satellite system outage statistics for each of the six years and the six year average, (2) detailed cable

G. S. Li

1977-01-01

264

Computer-Aided Communication Satellite System Analysis and Optimization.  

ERIC Educational Resources Information Center

Various published computer programs for fixed/broadcast communication satellite system synthesis and optimization are discussed. The rationale for selecting General Dynamics/Convair's Satellite Telecommunication Analysis and Modeling Program (STAMP) in modified form to aid in the system costing and sensitivity analysis work in the Program on…

Stagl, Thomas W.; And Others

265

Hybrid Global Communication Architecture with Balloons and Satellites  

Microsoft Academic Search

Global space communication systems have been developed now for more than three decades, based mainly on geostationary satellites or almost equivalent systems such as the Molnya orbit concepts. The last decade of the twentieth century has seen the emergence of satellite constellations in low or medium Earth orbit, in order to improve accessibility in terms of visibility at higher latitudes

G. Pignolet; A. Celeste; B. Erb

2002-01-01

266

Four configuration comparison for developing Chinese spin stabilization communication satellite  

NASA Astrophysics Data System (ADS)

A comparison among four different configurations based on DFH-2A technology has been made for developing Chinese spin stabilization communication satellite, after analyzing the development approach used abroad. The development strategy of a future development plan for this kind of satellite is the main factor in configuration selection.

Bao, Miaoqin

1992-04-01

267

Estimating Effects Of Rain On Ground/Satellite Communication  

NASA Technical Reports Server (NTRS)

LeRC-SLAM provides static and dynamic statistical assessment of impact of attenuation by rain on communication link established between Earth terminal and geosynchronous satellite. Program designed for use in specification, design, and assessment of satellite link for any terminal location in continental United States. IBM PC version written in Microsoft QuickBASIC, and Macintosh version written in Microsoft Basic.

Manning, R. M.

1992-01-01

268

The optical communication link outage probability in satellite formation flying  

NASA Astrophysics Data System (ADS)

In recent years, several space systems consisting of multiple satellites flying in close formation have been proposed for various purposes such as interferometric synthetic aperture radar measurement (TerraSAR-X and the TanDEM-X), detecting extra-solar earth-like planets (Terrestrial Planet Finder-TPF and Darwin), and demonstrating distributed space systems (DARPA F6 project). Another important purpose, which is the concern of this paper, is for improving radio frequency communication to mobile terrestrial and maritime subscribers. In this case, radio frequency signals from several satellites coherently combine such that the received/transmit signal strength is increased proportionally with the number of satellites in the formation. This increase in signal strength allows to enhance the communication data rate and/or to reduce energy consumption and the antenna size of terrestrial mobile users' equipment. However, a coherent combination of signals without aligning the phases of the individual communication signals interrupts the communication and outage link between the satellites and the user. The accuracy of the phase estimation is a function of the inter-satellite laser ranging system performance. This paper derives an outage probability model of a coherent combination communication system as a function of the pointing vibration and jitter statistics of an inter-satellite laser ranging system tool. The coherent combination probability model, which could be used to improve the communication to mobile subscribers in air, sea and ground is the main importance of this work.

Arnon, Shlomi; Gill, Eberhard

2014-02-01

269

Global maritime mobile service via satellite - The INMARSAT system now and in the future  

NASA Astrophysics Data System (ADS)

The business and technical aspects of the INMARSAT (International Maritime Satellite Organization) system are reviewed along with its present capabilities and services and future developments now being considered. The initial phase of maritime mobile satellite communications began with the introduction by the U.S. of the Marisat system in 1976, satisfying a commitment made by COMSAT (Communications Satellite Corp.) in 1973 to provide a maritime satellite service. The Marisat Consortium, spun off by COMSAT, launched three satellites in 1973 - one to serve shipping in the Atlantic, one for the Pacific, and the third as a spare; the spare was subsequently positioned over the Indian Ocean so that the three provided almost global coverage. Each satellite was served by a coast earth station with a 13-m antenna; satellite-earth station links operated in the 6 and 4-GHz bands and the ship-satellite links were at 1.5 and 1.6 GHz. Superceding the limited Marisat system, the INMARSAT Organization, established in July 1979 and first in service on Feb. 1, 1982, now provides communications through a system of Marecs, Intelsat-V, and Marisat satellites. With 41 Signatories by mid-1985, the organization consists of an Assembly, a Council, and a Directorate. Services provided include: telephone; facsimile; low-speed data; high-speed data; telex; telegram; distress, urgency and safety communications; shore-to-ship group calls; various information and assistance services. Coast earth stations, ship earth stations, network coordination stations, and the London headquarters and operations control center are described. Future developments will include an expanded capacity network, digital services, and a role in the Future Global Maritime Distress and Safety System that will use radio beacons that will automatically transmit distress messages to land-based emergency centers in the event of a disaster at sea.

Snowball, A. E.

1986-06-01

270

Coded Modulations for Mobile Satellite Communication Channels  

NASA Astrophysics Data System (ADS)

The mobile satellite (MSAT) channel is subject to multipath fading, shadowing, Doppler frequency shift, and adjacent channel interference (ACI). Therefore, transmitted signals face severe amplitude and phase distortions. This dissertation investigates various high performance and low decoding complexity coded modulation schemes for reliable voice and data transmissions over the shadowed mobile satellite channel and the Rayleigh fading channel. The dissertation consists of four parts. The first part presents a systematic technique for constructing MPSK trellis coded modulation (TCM) codes for voice transmission over the MSAT channel. The multilevel coding method is used for constructing TCM codes using convolutional codes with good free branch distances as the component codes or using both convolutional and block codes as the component codes. Simulation results show that these codes achieve good coding gains over the uncoded reference system and outperform existing TCM codes with the same decoding complexity. In the second part, using the multilevel coding method, multilevel block coded modulation (BCM) codes are constructed for voice transmission over the MSAT channel. Even though BCM is generally less power efficient than TCM for AWGN channels, BCM has a great potential to compete with TCM in the MSAT channel because of its shorter decoding depth and hence more effective interleaving. Binary Reed -Muller (RM) codes of length up to 32 are used as component codes. Simulation results show that these codes achieve good coding gains over the uncoded reference system and outperform TCM codes with the same decoding complexity. In the third part, a simple and systematic technique for constructing multilevel concatenated BCM schemes for data transmission over the shadowed MSAT channel and the Rayleigh fading channel is presented. These schemes are designed to achieve high-performance or large coding gain with reduced decoding complexity. Construction is based on a multilevel concatenation approach in which long powerful (binary or non-binary) codes are used as the outer codes and coset codes constructed from a linear BCM code and its subcodes are used as the inner codes. Simulation results show that these codes achieve large coding gains over the uncoded reference system and outperform single-level concatenated BCM codes with the same inner codes. Especially, some multilevel concatenated BCM codes achieve an error-floor free communication at BER of 10^{-5 }. In the final part of the dissertation, product coded modulation schemes are constructed by using multilevel concatenating approach. In product coded modulation, the product coding technique and coded modulation are combined to achieve high performance with reduced decoding complexity. Good product 8-PSK modulation codes are constructed for various shadowed MSAT channels. Simulation results show that these codes achieve large coding gains over the uncoded reference system and outperform single-level concatenated BCM codes with the same inner codes.

Rhee, Dojun

1995-01-01

271

COMMUNICATION SATELLITES FOR EDUCATION, SCIENCE AND CULTURE. REPORTS AND PAPERS ON MASS COMMUNICATION, NO. 53.  

ERIC Educational Resources Information Center

THE TECHNOLOGY OF COMMUNICATION SATELLITES IS SUFFICIENTLY ADVANCED THAT CONCERNED AGENCIES, SUCH AS UNESCO, SHOULD BEGIN TO PLAN FOR THEIR USE IN EXCHANGE OF DATA, NEWS TRANSMISSION, CULTURAL EXCHANGE, AND EDUCATION. GROUNDWORK IN TECHNOLOGY, IN THE DESIGN OF A SATELLITE COMMUNICATION SYSTEM, IN VALUE JUDGMENTS, IN AGREEMENTS OF COOPERATION AND…

SCHRAMM, WILBUR

272

President's Task Force on Communications Policy. Domestic Applications of Communication Satellite Technology. Staff Paper Four.  

ERIC Educational Resources Information Center

A staff paper to the President's Task Force on Communications Policy examines the feasibility of a domestic communications satellite system. Although, with expected technological advancement, satellites may play a significant role in domestic transmission and are economically feasible right now, a number of remaining questions make the…

President's Task Force on Communications Policy, Washington, DC.

273

Development and performance of an L-band phased array antenna for mobile satellite communications  

Microsoft Academic Search

The previous years have witnessed an introduction of a large number of mobile satellite (MSS) communications systems. These include a global GEO MSS system, Inmarsat, and domestic GEO MSS systems such as North-American AMSC, Japan's N-Star and the Australian Mobilesat. At present, two types of antennas can be used to access GEO MSS services. They include (1) fixed position antennas,

N. C. Karmakar; M. E. Bialkowskilr

1999-01-01

274

Integrating satellite and terrestrial technologies for emergency communications: the WISECOM project  

Microsoft Academic Search

In this paper, the main concepts of the Wireless Infrastructure over Satellite for Emergency COMmunications project (WISECOM) are presented. These concepts rely upon the idea of a light and rapidly deployable system that can be autonomously used in remote areas where telecommunication networks have broken down to provide access to emergency telecommunication services using a large set of wide-spread telecommunication

Matteo Berioli; Nicolas Courville; Markus Werner

2007-01-01

275

Advanced Technologies and Satellite Services for Enhancing Space Surveillance  

NASA Astrophysics Data System (ADS)

Space-based systems are becoming part of our infrastructure and our dependency on space-based services has grown. Therefore, the assured availability and operational readiness of space-based services is essential, undoubtedly. However, satellites are subject to a variety of damaging effects and potential threats. These are mostly caused by an increasingly crowded region of outer space, by space weather including solar events and, unfortunately, even attacks on space systems which are no longer sience fiction as impressively demonstrated in 2007 with the Chinese anti-satellite test and the intercept of USA-193 in 2008. Today, German armed forces use several space services primarily for reconnaissance, communications and navigation. As a matter of fact, Germany`s sovereignty and national security depend on the availability of multiple space services. This led the Federal Ministry of Defence to set up a dedicated military Space Situational Awareness Centre at Kalkar/Uedem, Germany, as a significant contribution to a national preventive security. This paper provides information on a range of technical issues related to space assets that are important for anyone involved in the debate over space security and gives a brief survey of the German SSA program. The paper deals with a subset of feasible man-made threats and its fatal effects on space assets. Furthermore, the preliminary conceptual design of an onboard sensor suitable for the instant detection of the previously described types of threats is presented. Finally, advanced technologies for the near real-time transfer of data are highlighted.

2010-08-01

276

Communication satellite technology: State of the art and development opportunities  

NASA Technical Reports Server (NTRS)

Opportunities in communication satellite technology are identified and defined. Factors that tend to limit the ready availability of satellite communication to an increasingly wide group of users are evaluated. Current primary limitations on this wide utilization are the availability of frequency and/or synchronous equatorial satellite positions and the cost of individual user Earth terminals. The former could be ameliorated through the reuse of frequencies, the use of higher frequency bands, and the reduction of antenna side lobes. The latter limitation requires innovative hardware, design, careful system design, and large scale production.

Woodford, J. B. (compiler)

1978-01-01

277

Communication Practices in Employee & Campus Services  

E-print Network

Page 1 Communication Practices in Employee & Campus Services The University of Texas at Austin Fall of Communication Studies 512-695-9183 or keristephens@mail.utexas.edu Research Assistants: Stephanie L. Dailey Students, Department of Communication Studies #12;1.0 Executive Summary Page 2 1.1 Study Summary

Yang, Zong-Liang

278

Secure Satellite Communications and Turbo-like Codes  

Microsoft Academic Search

Various error control codes have been used before to provide a dual role, that is to correct errors and improve the level of security in a communications system. This paper shows how turbo-like codes can also help increase the level of security in a satellite communication system at no extra cost in system resources or decrease in performance. The basic

Sorin Adrian Barbulescu

279

An overview of the communications technology satellite project: Executive summary  

NASA Technical Reports Server (NTRS)

An overview of the Communications Technology Satellite (CTS) project, a joint venture between NASA and the Canadian Department of Communications is given. A brief technical description of the CTS spacecraft and its cognate hardware and operations, a history of the CTS project, and a list of the CTS experiments and demonstrations conducted during the course of the project are given.

Rapp, W.; Ogden, D.; Wright, D.

1982-01-01

280

Satellite to Submarine Laser Communications (SLC): Advanced filter technology  

Microsoft Academic Search

This final report describes results of work to design, fabricate, and test narrow bandwidth, wide field of view (FOV) acousto-optic tunable filters (AOTF's) operating in the green spectral region. Such filters have potential for application in satellite to submarine optical communications (SLC) links. The AOTF tunability has advantages for both downlink and uplink communications. The motivation of the technical approach

John D. Feichtner

1992-01-01

281

Land vehicle antennas for satellite mobile communications  

NASA Technical Reports Server (NTRS)

The RF performance, size, pointing system, and cost were investigated concepts are: for a mechanically steered 1 x 4 tilted microstrip array, a mechanically steered fixed-beam conformal array, and an electronically steered conformal phased array. Emphasis is on the RF performance of the tilted 1 x 4 antenna array and methods for pointing the various antennas studied to a geosynchronous satellite. An updated version of satellite isolations in a two-satellite system is presented. Cost estimates for the antennas in quantities of 10,000 and 100,000 unites are summarized.

Haddad, H. A.; Pieper, B. V.; Mckenna, D. B.

1985-01-01

282

Analysis of satellite servicing cost benefits  

NASA Technical Reports Server (NTRS)

Under the auspices of NASA/JSC a methodology was developed to estimate the value of satellite servicing to the user community. Time and funding precluded the development of an exhaustive computer model; instead, the concept of Design Reference Missions was involved. In this approach, three space programs were analyzed for various levels of servicing. The programs selected fall into broad categories which include 80 to 90% of the missions planned between now and the end of the century. Of necessity, the extrapolation of the three program analyses to the user community as a whole depends on an average mission model and equivalency projections. The value of the estimated cost benefits based on this approach depends largely on how well the equivalency assumptions and the mission model match the real world. A careful definition of all assumptions permits the analysis to be extended to conditions beyond the scope of this study.

Builteman, H. O.

1982-01-01

283

Communication protocols and on-board processor for a new national scale private mobile radio service [medical information environment  

Microsoft Academic Search

A satellite-aided mobile radio communication service opens a new horizon of the integrated medical information environment. Doctors of medicine working on fixed or mobile stations, located in remote geographical areas, are able to communicate\\/cooperate each other by exchanging, handling and processing medical data simultaneously. The authors present a new national scale private mobile radio service using satellite facilities. This new

S. Kotsopoulos; D. Lymberopoulos

1992-01-01

284

Human interfaces for robotic satellite servicing  

NASA Astrophysics Data System (ADS)

On-orbit servicing (OOS) is growing in importance for the sustainment of certain satellite systems. Although it is more economical to replace satellites in many cases, OOS could be beneficial, or even critical, for more expensive satellites such as Space-Based Laser and constellations such as the Global Positioning System. Some future OOS missions including refueling and modular component replacement will be highly autonomous, but there will still be a need for humans to supervise and to recover when unexpected situations arise. Non-routine tasks such as damage repair or optics cleaning will likely require a more significant level of human control. The human interfaces for such activities can include body tracking systems, three-dimensional audio and video, tactile feedback devices, and others. This paper will provide some insights into when and at what level human interaction may be needed for OOS tasks. Example missions will be discussed and the argument will be made that human interfaces are important even for primarily autonomous missions. Finally some current research efforts within NASA, academia and the military will be discussed including research being conducted in the Air Force Research Laboratory at Wright-Patterson Air Force Base.

Ianni, John; Repperger, Daniel; Baker, Robert W.; Williams, Robert L.

2002-06-01

285

Advanced Communications Technology Satellite (ACTS): Four-Year System Performance  

NASA Technical Reports Server (NTRS)

The Advanced Communications Technology Satellite (ACTS) was conceived at the National Aeronautics and Space Administration (NASA) in the late 1970's as a follow-on program to ATS and CTS to continue NASA's long history of satellite communications projects. The ACTS project set the stage for the C-band satellites that started the industry, and later the ACTS project established the use of Ku-band for video distribution and direct-to-home broadcasting. ACTS, launched in September 1993 from the space shuttle, created a revolution in satellite system architecture by using digital communications techniques employing key technologies such as a fast hopping multibeam antenna, an on-board baseband processor, a wide-band microwave switch matrix, adaptive rain fade compensation, and the use of 900 MHz transponders operating at Ka-band frequencies. This paper describes the lessons learned in each of the key ACTS technology areas, as well as in the propagation investigations.

Acosta, Roberto J.; Bauer, Robert; Krawczyk, Richard J.; Reinhart, Richard C.; Zernic, Michael J.; Gargione, Frank

1999-01-01

286

EHF (28/19 GHz) personal communications satellite terminal development  

NASA Technical Reports Server (NTRS)

The concept of communicating on a personal basis using a small terminal has been investigated globally from many different applications and technology perspectives. Applications range from terrestrial handheld communicators for paging, cellular, zone voice/data networks, etc., to satellite terminals of pocket dimensions for voice/low speed data or similar terminals using larger antennas for VSAT, news gathering (30 cm), and video (1.2 m). A brief status of some developments in the satellite personal communications at CRC will be presented.

Pike, Corey

1991-01-01

287

Aeronautical mobile satellite service: Air traffic control applications  

NASA Technical Reports Server (NTRS)

Canada's history both in aviation and in satellite communications development spans several decades. The introduction of aeronautical mobile satellite communications will serve our requirements for airspace management in areas not served by line-of-sight radio and radar facilities. The ensuing improvements in air safety and operating efficiency are eagerly awaited by the aviation community.

Sim, Dave

1990-01-01

288

Leo Satellite Communication through a LEO Constellation using TCP/IP Over ATM  

NASA Technical Reports Server (NTRS)

The simulated performance characteristics for communication between a terrestrial client and a Low Earth Orbit (LEO) satellite server are presented. The client and server nodes consist of a Transmission Control Protocol /Internet Protocol (TCP/IP) over ATM configuration. The ATM cells from the client or the server are transmitted to a gateway, packaged with some header information and transferred to a commercial LEO satellite constellation. These cells are then routed through the constellation to a gateway on the globe that allows the client/server communication to take place. Unspecified Bit Rate (UBR) is specified as the quality of service (QoS). Various data rates are considered.

Foore, Lawrence R.; Konangi, Vijay K.; Wallett, Thomas M.

1999-01-01

289

A satellite-based personal communication system for the 21st century  

NASA Technical Reports Server (NTRS)

Interest in personal communications (PCOMM) has been stimulated by recent developments in satellite and terrestrial mobile communications. A personal access satellite system (PASS) concept was developed at the Jet Propulsion Laboratory (JPL) which has many attractive user features, including service diversity and a handheld terminal. Significant technical challenges addressed in formulating the PASS space and ground segments are discussed. PASS system concept and basic design features, high risk enabling technologies, an optimized multiple access scheme, alternative antenna coverage concepts, the use of non-geostationary orbits, user terminal radiation constraints, and user terminal frequency reference are covered.

Sue, Miles K.; Dessouky, Khaled; Levitt, Barry; Rafferty, William

1990-01-01

290

Propagation considerations for emerging satellite communications applications  

Microsoft Academic Search

The effects of rain and other propagation concerns for new applications areas, currently in operation or planned for implementation by the end of this decade, are described. The areas include: VSAT systems employing low operating margins and\\/or low elevation angles; traditional communications applications operating with inclined geosynchronous orbits; and mobile and personal communications applications employing networks of low earth orbit

THOMAS A. RUSSELL

1993-01-01

291

GSFC conceptual design study for an inter-satellite Optical Multiple Access communication system  

NASA Technical Reports Server (NTRS)

System and terminal level specifications for an inter-satellite Optical Multiple Access (OMA) communication system are presented, as well as the resulting hardware designs for both OMA relay and OMA user terminals. The OMA relay terminal design uses a mechanical innovation which moves multiple fiber optic pickups in the focal plane, thereby providing simultaneous links with multiple OMA user terminals via a single telescope. Thus, with such a terminal on a relay satellite, multiple access service can be provided with a minimum of impact on the relay satellite.

Fox, Neil; Maynard, Will; Clarke, Ernest; Bruno, Ronald

1991-01-01

292

Land mobile communications satellite missions (LAMOCOSAMIS) task 4: Hybrid system concept  

NASA Astrophysics Data System (ADS)

The possibility of a hybrid satellite/terrestrial network for land mobile communication in Europe was assessed. The interdependency of the system parameters makes the problem of satellite mission difficult to approach, and the regulatory context (no frequency allocation for land mobile satellite service in Europe) offers more fields of investigation, as UHF and L-Band have to be considered as candidate frequency bands. It is shown that in L-Band, a capacity of 100 telephone channels is possible with spacecraft of the EUROSTAR class, indicating that a hybrid concept is attractive.

1985-12-01

293

Evaluation of spacecraft technology programs (effects on communication satellite business ventures), volume 1  

NASA Technical Reports Server (NTRS)

Commercial organizations as well as government agencies invest in spacecraft (S/C) technology programs that are aimed at increasing the performance of communications satellites. The value of these programs must be measured in terms of their impacts on the financial performane of the business ventures that may ultimately utilize the communications satellites. An economic evaluation and planning capability was developed and used to assess the impact of NASA on-orbit propulsion and space power programs on typical fixed satellite service (FSS) and direct broadcast service (DBS) communications satellite business ventures. Typical FSS and DBS spin and three-axis stabilized spacecraft were configured in the absence of NASA technology programs. These spacecraft were reconfigured taking into account the anticipated results of NASA specified on-orbit propulsion and space power programs. In general, the NASA technology programs resulted in spacecraft with increased capability. The developed methodology for assessing the value of spacecraft technology programs in terms of their impact on the financial performance of communication satellite business ventures is described. Results of the assessment of NASA specified on-orbit propulsion and space power technology programs are presented for typical FSS and DBS business ventures.

Greenburg, J. S.; Gaelick, C.; Kaplan, M.; Fishman, J.; Hopkins, C.

1985-01-01

294

Satellite communications provisions on NASA Ames instrumented aircraft platforms for Earth science research/applications  

NASA Technical Reports Server (NTRS)

Earth science activities at NASA Ames are research in atmospheric and ecosystem science, development of remote sensing and in situ sampling instruments, and their integration into scientific research platform aircraft. The use of satellite communications can greatly extend the capability of these agency research platform aircraft. Current projects and plans involve satellite links on the Perseus UAV and the ER-2 via TDRSS and a proposed experiment on the NASA Advanced Communications Technology Satellite. Provisions for data links on the Perseus research platform, via TDRSS S-band multiple access service, have been developed and are being tested. Test flights at Dryden are planned to demonstrate successful end-to-end data transfer. A Unisys Corp. airborne satcom STARLink system is being integrated into an Ames ER-2 aircraft. This equipment will support multiple data rates up to 43 Mb/s each via the TDRS S Ku-band single access service. The first flight mission for this high-rate link is planned for August 1995. Ames and JPL have proposed an ACTS experiment to use real-time satellite communications to improve wildfire research campaigns. Researchers and fire management teams making use of instrumented aircraft platforms at a prescribed burn site will be able to communicate with experts at Ames, the U.S. Forest Service, and emergency response agencies.

Shameson, L.; Brass, J. A.; Hanratty, J. J.; Roberts, A. C.; Wegener, S. S.

1995-01-01

295

Satellite radio interface and radio resource management strategy for the delivery of multicast\\/broadcast services via an integrated satellite-terrestrial system  

Microsoft Academic Search

A variety of hybrid systems combining third-generation mobile communication networks with broadcast systems have been proposed for the delivery of multimedia broadcast multicast services (MBMS) to mobile users. The article discusses one of these alternatives, which involves the use of a geostationary satellite component for MBMS delivery. In particular, it proposes a radio access scheme for the satellite component of

M. Karaliopoulos; K. Narenthiran; B. Evans; P. Henrio; M. Mazzella; W. de Win; M. Dieudonne; P. Philippopoulos; D. I. Axiotis; I. Andrikopoulos; I. Mertzanis; G. E. Corazza; A. Vanelli-Coralli; N. Dimitriou; A. Polydoros

2004-01-01

296

Communications Satellite Receiver Systems for Public Schools: A Technical Primer.  

ERIC Educational Resources Information Center

Designed to aid school districts contemplating use of some of the telecommunications services now available by satellite, this document contains information on home satellite receiving dishes (Television Receive-Only--TVROs), which can receive radio signals carrying television, sound, and data. This information includes: some factors involved in…

Texas Education Agency, Austin.

297

The principle of a navigation constellation composed of SIGSO communication satellites  

NASA Astrophysics Data System (ADS)

The Chinese Area Positioning System (CAPS), a navigation system based on geostationary orbit (GEO) communication satellites, was developed in 2002 by astronomers at Chinese Academy of Sciences. Extensive positioning experiments of CAPS have been performed since 2005. On the basis of CAPS, this paper studies the principle of a navigation constellation composed of slightly inclined geostationary orbit (SIGSO) communication satellites. SIGSO satellites are derived from GEO satellites which are near the end of their operational life by inclined orbit operation. Considering the abundant frequency resources of SIGSO satellites, multi-frequency observations could be conducted to enhance the precision of pseudorange measurements and ameliorate the positioning performance. A constellation composed of two GEO satellites and four SIGSO satellites with an inclination of 5° can provide service to most of the territory of China with a maximum position dilution of precision (PDOP) over 24 h of less than 42. With synthetic utilization of the truncated precise code and a physical augmentation factor in four frequencies, the navigation system with this constellation is expected to obtain comparable positioning performance to that of the coarse acquisition code of the Global Positioning System (GPS). When the new method of code-carrier phase combinations is adopted, the system has the potential to possess commensurate accuracy with the precise code in GPS. Additionally, the copious frequency resources can also be used to develop new anti-interference techniques and integrate navigation and communication.

Ji, Hai-Fu; Ma, Li-Hua; Ai, Guo-Xiang; Shi, Hu-Li

2013-04-01

298

Study of LEO-SAT microwave link for broad-band mobile satellite communication system  

NASA Technical Reports Server (NTRS)

In the field of mobile satellite communications, a system based on low-earth-orbit satellites (LEO-SAT's) such as the Iridium system has been proposed. The LEO-SAT system is able to offer mobile telecommunication services in high-latitude areas. Rain degradation, fading and shadowing are also expected to be decreased when the system is operated at a high elevation angle. Furthermore, the propagation delay generated in the LEO-SAT system is less pronounced than that in the geostationary orbit satellite (GEO-SAT) system and, in voice services, the effect of the delay is almost negligible. We proposed a concept of a broad-band mobile satellite communication system with LEO-SAT's and Optical ISL. In that system, a fixed L-band (1.6/1.5 GHz) multibeam is used to offer narrow band service to the mobile terminals in the entire area covered by a LEO-SAT and steerable Ka-band (30/20 GHz) spot beams are used for the wide band service. In this paper, we present results of a study of LEO-SAT microwave link between a satellite and a mobile terminal for a broad-band mobile satellite communication system. First, the results of link budget calculations are presented and the antennas mounted on satellites are shown. For a future mobile antenna technology, we also show digital beamforming (DBF) techniques. DBF, together with modulation and/or demodulation, is becoming a key technique for mobile antennas with advanced functions such as antenna pattern calibration, correction, and radio interference suppression. In this paper, efficient DBF techniques for transmitting and receiving are presented. Furthermore, an adaptive array antenna system suitable for this LEO-SAT is presented.

Fujise, Masayuki; Chujo, Wataru; Chiba, Isamu; Furuhama, Yoji; Kawabata, Kazuaki; Konishi, Yoshihiko

1993-01-01

299

47 CFR 64.617 - Neutral Video Communication Service Platform.  

Code of Federal Regulations, 2013 CFR

...2013-10-01 2013-10-01 false Neutral Video Communication Service Platform. 64...With Disabilities § 64.617 Neutral Video Communication Service Platform. ...Commission are required to utilize the Neutral Video Communication Service Platform to...

2013-10-01

300

Personal communications: An extension to the mobile satellite  

NASA Technical Reports Server (NTRS)

As time progresses, customer demands become far more universal, involving integrated, simple to operate, cost effective services, with technology virtually transparent to the operator. Industry will be in a position of providing the necessary services to meet the subscribers' needs. Our resource based industries, transportation services, and utilities in the more rural and unserviced areas will require quality and affordable services that can only be supplied via satellite. One answer to these needs will be one- and two-way interoperable data messaging.

Epstein, Murray; Draper, Francois

1990-01-01

301

Spread spectrum mobile communication experiment using ETS-V satellite  

NASA Technical Reports Server (NTRS)

The spread spectrum technique is attractive for application to mobile satellite communications, because of its random access capability, immunity to inter-system interference, and robustness to overloading. A novel direct sequence spread spectrum communication equipment is developed for land mobile satellite applications. The equipment is developed based on a matched filter technique to improve the initial acquisition performance. The data rate is 2.4 kilobits per sec. and the PN clock rate is 2.4552 mega-Hz. This equipment also has a function of measuring the multipath delay profile of land mobile satellite channel, making use of a correlation property of a PN code. This paper gives an outline of the equipment and the field test results with ETS-V satellite.

Ikegami, Tetsushi; Suzuki, Ryutaro; Kadowaki, Naoto; Taira, Shinichi; Sato, Nobuyasu

1990-01-01

302

Computer-aided communication satellite system analysis and optimization  

NASA Technical Reports Server (NTRS)

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.; Morgan, N. H.; Morley, R. E.; Singh, J. P.

1973-01-01

303

High speed laser communication network for satellite systems  

NASA Astrophysics Data System (ADS)

Using optical links in space and building high speed laser communications network has proven to be an extremely complicated task and many such schemes were tried without success in the past. However, in the last few years, there has been impressive progress made to bring the concept to fruition in civilian and government-non classified projects. In this paper we will focus on the requirements of the space-based lasers and optics used for beam forming, as well as receiver antenna gain and detectors used in free space communications. High data rate, small antenna size, narrow beam divergence, and a narrow field of view are characteristics of laser communications that offer a number of potential advantages for system design. Space-based optical communications using satellites in low earth orbit (LEO) and Geo-synchronous orbits (GEO) hold great promise for the proposed Internet in the Sky network of the future. Also discussed are the critical parameters in the transmitter, channel, receiver, and link budget that are employed in successful inter-satellite communications system. We cover that Laser Communications offer a viable alternative to established RF communications for inter-satellite links and other applications where high performance links are a necessity.

Panahi, Allen; Kazemi, Alex A.

2011-06-01

304

An adaptive array antenna for mobile satellite communications  

NASA Technical Reports Server (NTRS)

The design of an adaptive array antenna for land vehicle operation and its performance in an operational satellite system is described. Linear and circularly polarized antenna designs are presented. The acquisition and tracking operation of a satellite is described and the effect on the communications signal is discussed. A number of system requirements are examined that have a major impact on the antenna design. The results of environmental, power handling, and RFI testing are presented and potential problems are identified.

Milne, Robert

1990-01-01

305

Optical deep space communication via relay satellite  

NASA Technical Reports Server (NTRS)

The possible use of an optical for high rate data transmission from a deep space vehicle to an Earth-orbiting relay satellite while RF links are envisioned for the relay to Earth link was studied. A preliminary link analysis is presented for initial sizing of optical components and power levels, in terms of achievable data rates and feasible range distances. Modulation formats are restricted to pulsed laser operation, involving bot coded and uncoded schemes. The advantage of an optical link over present RF deep space link capabilities is shown. The problems of acquisition, pointing and tracking with narrow optical beams are presented and discussed. Mathematical models of beam trackers are derived, aiding in the design of such systems for minimizing beam pointing errors. The expected orbital geometry between spacecraft and relay satellite, and its impact on beam pointing dynamics are discussed.

Gagliardi, R. M.; Vilnrotter, V. A.; Dolinar, S. J., Jr.

1981-01-01

306

Shuttle station, and satellite communications program  

NASA Technical Reports Server (NTRS)

A parametric approach is developed to analyze and evaluate the performance of any link or links of a satellite relay system. The approach factors into the calculations the constraints of coherent radio frequency interference, multipath, and equipment design. The report is divided into three sections dealing with Spread Spectrum Techniques (Section 1), Power Budget Calculations (Section 2), and Required Capabilities and Design Factors for Tracking and Data Relay Systems TDRS (Section 3).

Lawsine, L.

1974-01-01

307

College curriculum-sharing via CTS. [Communications Technology Satellite  

NASA Technical Reports Server (NTRS)

Domestic communication satellites and video compression techniques will increase communication channel capacity and reduce cost of video transmission. NASA Ames Research Center, Stanford University and Carleton University are participants in an experiment to develop, demonstrate, and evaluate college course sharing techniques via satellite using video compression. The universities will exchange televised seminar and lecture courses via CTS. The experiment features real-time video compression with channel coding and quadra-phase modulation for reducing transmission bandwidth and power requirements. Evaluation plans and preliminary results of Carleton surveys on student attitudes to televised teaching are presented. Policy implications for the U.S. and Canada are outlined.

Hudson, H. E.; Guild, P. D.; Coll, D. C.; Lumb, D. R.

1975-01-01

308

Service outages in GPS associated with satellite failures  

Microsoft Academic Search

The planned NAVSTAR\\/GPS satellite constellation of 18 satellites plus 3 active spares will provide excellent coverage over the CONUS if all are operating properly. This report examines the coverage under conditions of one satellite failure. It turns out that the failure of any satellie results in service outages of up to half an hour somewhere in the CONUS. While altimeter

R. M. Kalafus

1984-01-01

309

Modulation/demodulation techniques for satellite communications. Part 1: Background  

NASA Technical Reports Server (NTRS)

Basic characteristics of digital data transmission systems described include the physical communication links, the notion of bandwidth, FCC regulations, and performance measurements such as bit rates, bit error probabilities, throughputs, and delays. The error probability performance and spectral characteristics of various modulation/demodulation techniques commonly used or proposed for use in radio and satellite communication links are summarized. Forward error correction with block or convolutional codes is also discussed along with the important coding parameter, channel cutoff rate.

Omura, J. K.; Simon, M. K.

1981-01-01

310

Acquisition and pointing control for inter-satellite laser communications  

Microsoft Academic Search

Communications and range estimation between formation members are essential functions of formation flying. The inherent features of laser free-space link: small weight and mass, power efficiency, broadband, high precision, availability of state-of-the-art components, make it a very attractive candidate for micro-satellite formation flying missions. A single two-way laser link, performing simultaneously communication and range estimation functions between formation spacecraft is

M. Guelman; A. Kogan; A. Kazarian; A. Livne; M. Orenstein; H. Michalik; S. Arnon

2004-01-01

311

Broadband and scalable mobile satellite communication system for future access networks  

NASA Astrophysics Data System (ADS)

Due to the recent market trends, NTT has begun research into next generation satellite communication systems, such as broadband and scalable mobile communication systems. One service application objective is to provide broadband Internet access for transportation systems, temporal broadband access networks and telemetries to remote areas. While these are niche markets the total amount of capacity should be significant. We set a 1-Gb/s total transmission capacity as our goal. Our key concern is the system cost, which means that the system should be unified system with diversified services and not tailored for each application. As satellites account for a large portion of the total system cost, we set the target satellite size as a small, one-ton class dry mass with a 2-kW class payload power. In addition to the payload power and weight, the mobile satellite's frequency band is extremely limited. Therefore, we need to develop innovative technologies that will reduce the weight and maximize spectrum and power efficiency. Another challenge is the need for the system to handle up to 50 dB and a wide data rate range of other applications. This paper describes the key communication system technologies; the frequency reuse strategy, multiplexing scheme, resource allocation scheme, and QoS management algorithm to ensure excellent spectrum efficiency and support a variety of services and quality requirements in the mobile environment.

Ohata, Kohei; Kobayashi, Kiyoshi; Nakahira, Katsuya; Ueba, Masazumi

2005-07-01

312

The Army's Use of the Advanced Communications Technology Satellite  

NASA Technical Reports Server (NTRS)

Tactical operations require military commanders to be mobile and have a high level of independence in their actions. Communications capabilities providing intelligence and command orders in these tactical situations have been limited to simple voice communications or low-rate narrow bandwidth communications because of the need for immediate reliable connectivity. The Advanced Communications Technology Satellite (ACTS) has brought an improved communications tool to the tactical commander giving the ability to gain access to a global communications system using high data rates and wide bandwidths. The Army has successfully tested this new capability of bandwidth-on-demand and high data rates for commanders in real-world conditions during Operation UPHOLD DEMOCRACY in Haiti during the fall and winter of 1994. This paper examines ACTS use by field commanders and details the success of the ACTS system in support of a wide variety of field condition command functions.

Ilse, Kenneth

1996-01-01

313

Utilization of photovoltaic for broadband satellite communications in rural area of Thailand  

NASA Astrophysics Data System (ADS)

Electricity, Information and Communication Technologies (ICTs) are very important not only in urban areas but also in rural areas. To provide ICTs service in rural areas, sources of electricity and communication infrastructures must be implemented. Electricity is a major condition due to the fact that all electronic devices needed it in order to power on, so that it is impossible to operate any forms of ICTs in areas where the main national grid line is unavailable. Almost rural areas of Thailand where the main national grid line is unavailable have very good sunlight intensity. Photovoltaic is the most effective renewable energy technologies in those areas for meeting electricity needed in areas that are not connected to the main national grid line. In this paper, the efficiency utilization of photovoltaic as source of electricity for broadband satellite communication systems as well as social and economic impact and quality of life of people in rural areas of Thailand are presented. The results show that most rural communities would be able to universally access to the basic telecommunications services such as internet access and public telephone via satellite communication systems. However, in some field case study, broadband internet access via satellite communication may be unnecessary for some rural communities and the most exactly rural communities needed are electricity for household usage and battery charger.

Jinayim, Theerawut; Mungkung, Narong; Kasayapanand, Nat

2013-06-01

314

DS-CDMA satellite diversity reception for personal satellite communication: Downlink performance analysis  

NASA Technical Reports Server (NTRS)

The downlink of a satellite-mobile personal communication system employing power-controlled Direct Sequence Code Division Multiple Access (DS-CDMA) and exploiting satellite-diversity is analyzed and its performance compared with a more traditional communication system utilizing single satellite reception. The analytical model developed has been thoroughly validated by means of extensive Monte Carlo computer simulations. It is shown how the capacity gain provided by diversity reception shrinks considerably in the presence of increasing traffic or in the case of light shadowing conditions. Moreover, the quantitative results tend to indicate that to combat system capacity reduction due to intra-system interference, no more than two satellites shall be active over the same region. To achieve higher system capacity, differently from terrestrial cellular systems, Multi-User Detection (MUD) techniques are likely to be required in the mobile user terminal, thus considerably increasing its complexity.

DeGaudenzi, Riccardo; Giannetti, Filippo

1995-01-01

315

Emergency Communications over Satellite: the WISECOM Approach  

Microsoft Academic Search

This paper presents the overall architecture of the WISECOM system, which can quickly re-establish and provide telecommunication services after a disaster. The architecture is explained and it is described together with a role model, which adapts to the system. The work tries to map the existing complex interactions taking place nowadays in an emergency situation to a sensible architecture, which

M. Berioli; N. Courville; M. Werner

2007-01-01

316

Satellite Point-to-Multipoint Services for Information Dissemination: Opportunities and Economics.  

ERIC Educational Resources Information Center

Outlines the current status of satellite-delivered narrowcasting services in Europe; identifies potential applications, including electronic publishing and corporate data communications; compares various transmission technologies; and explores economic issues with the aid of a spreadsheet model for the cases of a facsimile broadcast and a weather…

Casewell, I. E.

1992-01-01

317

Improving Library Services to Satellite Campuses: The Case of the University of Lethbridge  

ERIC Educational Resources Information Center

A survey was done of instructors at two satellite campuses located at a distance from the main campus of the University of Lethbridge in order to ascertain both utilization and awareness of library resources and services. Results were enlightening, indicating that lack of awareness and communication is one of the biggest obstacles for these…

Eva, Nicole C.

2012-01-01

318

2011NOAA SATELLITE AND INFORMATION SERVICE Annual Repor t  

E-print Network

Technical Writers- Patricia Huff, Toni Parham, Ryan Quick Special thanks to the NESDIS Communications Teamth Warmest on Record NOAA Satellites Track Raging U.S. Wild El Niño-Southern Oscillation a 2010 One

319

Uplink Power Control For Earth/Satellite/Earth Communication  

NASA Technical Reports Server (NTRS)

Proposed control subsystem adjusts power radiated by uplink transmitter in Earth station/satellite relay station/ Earth station communication system. Adjustments made to compensate for anticipated changes in attenuation by rain. Raw input is a received downlink beacon singal, amplitude of which affected not only by rain fade but also by scintillation, attenuation in atmospheric gases, and diurnal effects.

Chakraborty, Dayamoy

1994-01-01

320

New Opportunities with the Advanced Communications Technology Satellite (ACTS)  

NASA Technical Reports Server (NTRS)

Various issues associated with the Advanced Communications Technology Satellite (ACTS) are presented in viewgraph form. Specific topics include: 1) ACTS program review; 2) Spot beam locations; 3) Key ACTS technologies; 4) ACTS accomplishments; 5) Experiments operations; 6) Inclined orbit opportunity, mission and impact; 7) Modifications summary; 8) Experiment opportunity, categories, processes; and 9) Recent and ongoing activity.

Bauer, Robert

1998-01-01

321

Operation of higher layer data communication protocols over satellite links  

Microsoft Academic Search

The International Standards Organization's (ISO's) seven-layer reference model for computer communication protocols is discussed. The layering arises out of the stratification of functions across the layers. The various protocol functions performed at each higher layer are examined in detail, identifying the appropriate procedures that affect the efficient operation of these protocols over satellite links for different ranges of transmission speeds

D. M. Chitre; Hsi-Ming Lee

1990-01-01

322

Achieving QoS for TCP Traffic in Satellite Networks with Differentiated Services  

NASA Technical Reports Server (NTRS)

Satellite networks play an indispensable role in providing global Internet access and electronic connectivity. To achieve such a global communications, provisioning of quality of service (QoS) within the advanced satellite systems is the main requirement. One of the key mechanisms of implementing the quality of service is traffic management. Traffic management becomes a crucial factor in the case of satellite network because of the limited availability of their resources. Currently, Internet Protocol (IP) only has minimal traffic management capabilities and provides best effort services. In this paper, we presented a broadband satellite network QoS model and simulated performance results. In particular, we discussed the TCP flow aggregates performance for their good behavior in the presence of competing UDP flow aggregates in the same assured forwarding. We identified several factors that affect the performance in the mixed environments and quantified their effects using a full factorial design of experiment methodology.

Durresi, Arjan; Kota, Sastri; Goyal, Mukul; Jain, Raj; Bharani, Venkata

2001-01-01

323

Applications of Multi Port Amplifier to personal satellite communications  

NASA Technical Reports Server (NTRS)

In personal satellite communications, satellite antenna beam becomes narrow, and number of beams will be thirty to more than one hundred. This paper shows that Multi Port Amplifier is most suitable to multiple beam transmitter for personal communications satellite. It was shown that the single beam coverage area(cell) diameter is determined by personal earth station(PES) eirp, uplink C/No and uplink frequency band. Required number of cells for European or North American regional coverage at FPLMTS uplink frequency band is shown as around 32. It was shown that 32 beams systems will be easily implemented by using 2 set of 16-port MPA. Redundancy to SSPA failure is considered by increasing number of SSPAs. Actual configuration for 16-port MPA are briefly shown. The presented configuration will be easy to implement and the most economical solution.

Egami, Shunichiro

1995-01-01

324

Fault-tolerant onboard digital information switching and routing for communications satellites  

NASA Technical Reports Server (NTRS)

The NASA Lewis Research Center is developing an information-switching processor for future meshed very-small-aperture terminal (VSAT) communications satellites. The information-switching processor will switch and route baseband user data onboard the VSAT satellite to connect thousands of Earth terminals. Fault tolerance is a critical issue in developing information-switching processor circuitry that will provide and maintain reliable communications services. In parallel with the conceptual development of the meshed VSAT satellite network architecture, NASA designed and built a simple test bed for developing and demonstrating baseband switch architectures and fault-tolerance techniques. The meshed VSAT architecture and the switching demonstration test bed are described, and the initial switching architecture and the fault-tolerance techniques that were developed and tested are discussed.

Shalkhauser, Mary JO; Quintana, Jorge A.; Soni, Nitin J.; Kim, Heechul

1993-01-01

325

Communication for improved health services.  

PubMed

Health education and communication efforts are critical elements in improving individual acceptance of vaccines and of community participation in immunization programs. In particular, communication efforts are needed to involve informal groups and community leaders in promoting preventive health measures. Oral rehydration therapy has a demonstrated efficacy in correcting dehydration and is felt to be an important household intervention to prevent dehydration, malnutrition, and death. Recognition of the usefulness of this simple and inexpensive technology has led to its incorporation into national health programs in most developing countries of the world. Yet, despite this recognized importance for the last decade, ORT was estimated by the World Health Organization to be appropriately used for only 4% of diarrheal episodes in children of developing countries in 1983. It is obvious, from evaluations of some ORT programs, that information on proper treatment of diarrhea is not being conveyed adequately to the public. The communication of the ORT message to the public and to health workers at all levels is of increasing importance. Some health programs can be cited for their successful use of communication techniques to achieve greater use of ORT. The Oral Therapy Extension Program of the Bangladesh Rural Advancement Committee was initiated 5 years ago. This program is built around oral rehydration workers who receive training in a 5-day course, 3 days in class and 2 in the field, and further training in teaching methods and communication skills to enable them to effectively deliver their ORT messages. Mass communication also has been used successfully in ORT programs. The Honduras Mass Media and Health Practices Project used a combination of radio, printed material, and interpersonal communication through health workers to popularize the use of a new ORS product. These interventions illustrate several important steps in communication of health messages: analysis of the local vocabulary and beliefs to enable optimal message design and implementation; pretesting as many messages, materials, and methods as possible; focusing on carefully selected sets of objectives and behaviors; and monitoring and improving the campaign while it is in progress. PMID:12340537

Black, R E

1985-01-01

326

Compatibility - A challenge to universal communications Global cables and satellite communication  

Microsoft Academic Search

The prognosis for worldwide communications is discussed from six viewpoints. A look at the future roles of satellites and submarine cables, an evaluation of the advances in international telephone routing, and a CCITT progress report are presented. The technical and economic tasks necessary to achieve compatibility are outlined, and Comsat's organizational structure, and its relationship to international communications, is appraised.

T. B. Westfall

1966-01-01

327

Communications Satellites: A New Channel for International Communications, A New Source of International Tension.  

ERIC Educational Resources Information Center

Communications satellites could be the subject of bitter and potentially dangerous international controversy. They threaten to upset the comfortable monopoly of internal national communications systems which have enrolled national governments to screen intrusions of unwanted information or ideas. The United Nations Working Committee on Direct…

Mickelson, Sig

328

Space station automation study-satellite servicing, volume 2  

NASA Technical Reports Server (NTRS)

Technology requirements for automated satellite servicing operations aboard the NASA space station were studied. The three major tasks addressed: (1) servicing requirements (satellite and space station elements) and the role of automation; (2) assessment of automation technology; and (3) conceptual design of servicing facilities on the space station. It is found that many servicing functions cloud benefit from automation support; and the certain research and development activities on automation technologies for servicing should start as soon as possible. Also, some advanced automation developments for orbital servicing could be effectively applied to U.S. industrial ground based operations.

Meissinger, H. F.

1984-01-01

329

Capacity as a consideration for providing aeronautical mobile satellite air traffic services in the US domestic airspace  

Microsoft Academic Search

A preliminary analysis of the capacity (number of aircraft) that could be handled by the first generation American Mobile Satellite Corporation (AMSC) system in the early part of the 21st century is reported. The analysis is based on assumptions for the service demand, the Aeronautical Telecommunication Network (ATN), the communications scheme, the satellite channel and the aircraft Earth station. Capacity

Curtis A. Shively

1992-01-01

330

Concepts for 18/30 GHz satellite communication system, volume 1  

NASA Technical Reports Server (NTRS)

Concepts for 18/30 GHz satellite communication systems are presented. Major terminal trunking as well as direct-to-user configurations were evaluated. Critical technologies in support of millimeter wave satellite communications were determined.

Jorasch, R.; Baker, M.; Davies, R.; Cuccia, L.; Mitchell, C.

1979-01-01

331

Communicating data quality through Web Map Services  

NASA Astrophysics Data System (ADS)

The sharing and visualization of environmental data through spatial data infrastructures is becoming increasingly common. However, information about the quality of data is frequently unavailable or presented in an inconsistent fashion. ("Data quality" is a phrase with many possible meanings but here we define it as "fitness for purpose" - therefore different users have different notions of what constitutes a "high quality" dataset.) The GeoViQua project (www.geoviqua.org) is developing means for eliciting, formatting, discovering and visualizing quality information using ISO and Open Geospatial Consortium (OGC) standards. Here we describe one aspect of the innovations of the GeoViQua project. In this presentation, we shall demonstrate new developments in using Web Map Services to communicate data quality at the level of datasets, variables and individual samples. We shall outline a new draft set of conventions (known as "WMS-Q"), which describe a set of rules for using WMS to convey quality information (OGC draft Engineering Report 12-160). We shall demonstrate these conventions through new prototype software, based upon the widely-used ncWMS software, that applies these rules to enable the visualization of uncertainties in raster data such as satellite products and the results of numerical simulations. Many conceptual and practical issues have arisen from these experiments. How can source data be formatted so that a WMS implementation can detect the semantic links between variables (e.g. the links between a mean field and its variance)? The visualization of uncertainty can be a complex task - how can we provide users with the power and flexibility to choose an optimal strategy? How can we maintain compatibility (as far as possible) with existing WMS clients? We explore these questions with reference to existing standards and approaches, including UncertML, NetCDF-U and Styled Layer Descriptors.

Blower, Jon; Roberts, Charles; Griffiths, Guy; Lewis, Jane; Yang, Kevin

2013-04-01

332

The design and fabrication of the satellite relative-movement trajectory simulator for inter-satellite laser communications  

Microsoft Academic Search

The characteristics of the terminals for the inter-satellite laser communication must be tested and verified on ground before flight test. Satellite relative-movement trajectory optical simulator is one of the most important devices of the ground test and verification system. It is used for simulation of the relative-movement between arbitrary satellites. Cooperating with the standard satellite laser communication terminal, the dynamical

Jianfeng Sun; Liren Liu; Maojin Yun; Dejiang Zhang; Nan Xu

2005-01-01

333

Advanced Communications Technology Satellite Now Operating in an Inclined Orbit  

NASA Technical Reports Server (NTRS)

The Advanced Communications Technology Satellite (ACTS) system has been modified to support operation in an inclined orbit that is virtually transparent to users, and plans are to continue this final phase of its operation through September 2000. The next 2 years of ACTS will provide a new opportunity for using the technologies that this system brought online over 5 years ago and that are still being used to resolve the technical issues that face NASA and the satellite industry in the area of seamless networking and interoperability with terrestrial systems. New goals for ACTS have been defined that align the program with recent changes in NASA and industry. ACTS will be used as a testbed to: Show how NASA and other Government agencies can use commercial systems for 1. future support of their operations Test, characterize, and resolve technical issues in using advanced communications 2. protocols such as asynchronous transfer mode (ATM) and transmission control protocol/Internet protocol (TCP/IP) over long latency links as found when interoperating satellites with terrestrial systems Evaluate narrow-spot-beam Ka-band satellite operation in an inclined orbit 3. Verify Ka-band satellite technologies since no other Ka-band system is yet 4. available in the United States

Bauer, Robert A.

1999-01-01

334

A Low Earth Orbit satellite marine communication system demonstration  

NASA Technical Reports Server (NTRS)

An application of Low Earth Orbit (LEO) satellite communications technology was investigated during a joint Canadian/American scientific expedition to the north pole in the summer of 1994. The Canadian ice breaker involved, was equipped with a store-and-forward LEO satellite terminal which was linked to a ground station in St. John's, Newfoundland, via the near-polar-orbiting satellite, HealthSat-l. The objective was to evaluate the performance of such a system while providing an alternate means of communications in the far north. The system performed well, given its inherent limitations. All 151 attempts to send data files to the ship were successful. Only two (2) of the 35 attempts to send files from the ship were unsuccessful. The files ranged in size from 0.1 to 60 Kbytes. In the high arctic, above 80 deg north, this system often provided the only practical means of data communications. This experiment demonstrated the potential of such a system for not-real-time communications with remote and/or mobile stations, and highlighted the many issues involved. This paper describes the project objectives, system configuration and experimental procedure used, related technical issues, trial results, future work, and conclusions.

Elms, T. Keith; Butt, Kenneth A.; Asmus, Ken W.

1995-01-01

335

Market Related System Analysis of Satellite Communication Networks  

NASA Astrophysics Data System (ADS)

The report is devoted to the technique of effectiveness analysis of communication space system with satellites in geostationary orbit using market models. The technique is worked out in order to choose the most optimal alternative of communication space system design. The alternative considered optimal and the system effective when the maximum profit from the system with limited system costs is achieved. The key point of the technique is a wide use of market models and application of market related parameters as an integral part of the design technique in order to secure the high commercial output of the communication space system. A range of models for decisive characteristics of communication space system is synthesized in terms of the technique. Flexible market model with detailed insight into the structure of the given market sector and its trends is created. The technique enables to choose the image and key parameters of the future system such as payload and ground sector characteristics so as to make the system most cost-effective and profitable. It is shown that such factors as the choice of launch vehicle can influence the system effectiveness rather dramatically. In particular, it is shown that under certain conditions delivering the small (five hundred kg) satellite to the geostationary orbit with the help of light-weight launch vehicle and the satellite's own electro-rocket thrusters is forty per cent more cost- effective than when the satellite is delivered with the help of the medium-size launch vehicle. The latter case can lead to the significant losses due to high launch costs that are nearly two times higher for the medium size launch vehicle than for the light launce vehicle. The technique is applicable both for designing a wide range of communication space systems and is recommended for those dealing with designing commercial systems. It can also be used to update and improve the systems that are already in operation.

Malyshev, V. V.; Panasenkova, M. V.

2002-01-01

336

Intelligent fault isolation and diagnosis for communication satellite systems  

NASA Technical Reports Server (NTRS)

Discussed here is a prototype diagnosis expert system to provide the Advanced Communication Technology Satellite (ACTS) System with autonomous diagnosis capability. The system, the Fault Isolation and Diagnosis EXpert (FIDEX) system, is a frame-based system that uses hierarchical structures to represent such items as the satellite's subsystems, components, sensors, and fault states. This overall frame architecture integrates the hierarchical structures into a lattice that provides a flexible representation scheme and facilitates system maintenance. FIDEX uses an inexact reasoning technique based on the incrementally acquired evidence approach developed by Shortliffe. The system is designed with a primitive learning ability through which it maintains a record of past diagnosis studies.

Tallo, Donald P.; Durkin, John; Petrik, Edward J.

1992-01-01

337

76 FR 66350 - Eighth Meeting: RTCA Special Committee 222 Inmarsat Aeronautical Mobile Satellite (Route) Services  

Federal Register 2010, 2011, 2012, 2013

...Special Committee 222 Inmarsat Aeronautical Mobile Satellite (Route) Services AGENCY...Committee 222, Inmarsat Aeronautical Mobile Satellite (Route) Services meeting...Committee 222, Inmarsat Aeronautical Mobile Satellite (Route) Services for the...

2011-10-26

338

75 FR 63534 - Seventh Meeting-Special Committee 222: Inmarsat Aeronautical Mobile Satellite (Route) Services  

Federal Register 2010, 2011, 2012, 2013

...222: Inmarsat Aeronautical Mobile Satellite (Route) Services...222: Inmarsat Aeronautical Mobile Satellite (Route) Services...222: Inmarsat Aeronautical Mobile Satellite (Route) Services...issues. Status of ATCt filter development activities with ARINC...

2010-10-15

339

Usage and protection of the earth exploration satellite service  

Microsoft Academic Search

Earth observations by microwave radiometers are typically performed at frequencies allocated for passive use to the Earth Exploration Satellite Service (EESS). Many of these allocations are shared with the Radio Astronomy Service (RAS) and are also often shared with generally compatible active services. The problem of RFI in spaceborne microwave radiometer data has been known since 1978 when it was

Jeffrey Piepmeier

2008-01-01

340

Advanced mobile satellite communications system using Ka and MM-wave bands in Japan's R and D satellite project  

NASA Technical Reports Server (NTRS)

Communications Research Laboratory (CRL) studied an advanced mobile satellite communications system using Ka and millimeter-wave bands in the R&D Satellite project. The project started in 1990 and the satellite will be launched in 1997. On-board multi-beam interconnecting is one of basic functions to realize one-hop connection among Very Small Aperture Terminals (VSATs), mobile, and hand-held terminals in future mobile satellite communications system. An Intermediate Frequency (IF) filter bank and regenerative transponder are suitable for this function. The transponder configuration of an advanced mobile communications mission of the R&D Satellite for experiment is shown. High power transmitters of Ka and millimeter-wave bands, a 3x3 IF filter band and Single Channel Per Carrier/Time Division Multiplexing (SCPC/TDM) regenerative MODEMS, which will be boarded on the R&D Satellite, are being developed for the purpose of studying the feasibility of advanced mobile communications system.

Isobe, Shunkichi; Ohmori, Shingo; Hamamoto, Naokazu; Yamamoto, Minoru

1991-01-01

341

Destination-directed, packet-switched architecture for a geostationary communications satellite network  

NASA Technical Reports Server (NTRS)

A major goal of the Digital Systems Technology Branch at the NASA Lewis Research Center is to identify and develop critical digital components and technologies that either enable new commercial missions or significantly enhance the performance, cost efficiency, and/or reliability of existing and planned space communications systems. NASA envisions a need for low-data-rate, interactive, direct-to-the-user communications services for data, voice, facsimile, and video conferencing. The network would provide enhanced very-small-aperture terminal (VSAT) communications services and be capable of handling data rates of 64 kbps through 2.048 Mbps in 64-kbps increments. Efforts have concentrated heavily on the space segment; however, the ground segment has been considered concurrently to ensure cost efficiency and realistic operational constraints. The focus of current space segment developments is a flexible, high-throughput, fault-tolerant onboard information-switching processor (ISP) for a geostationary satellite communications network. The Digital Systems Technology Branch is investigating both circuit and packet architectures for the ISP. Destination-directed, packet-switched architectures for geostationary communications satellites are addressed.

Ivancic, William D.; Shalkhauser, Mary JO; Bobinsky, Eric A.; Soni, Nitin J.; Quintana, Jorge A.; Kim, Heechul; Wager, Paul; Vanderaar, Mark

1993-01-01

342

Land Mobile Satellite Service (LMSS): A conceptual system design and identification of the critical technologies: Part 2: Technical report  

NASA Technical Reports Server (NTRS)

A conceptual system design for a satellite-aided land mobile service is described. A geostationary satellite which employs a large (55-m) UHF reflector to communicate with small inexpensive user antennas on mobile vehicles is discussed. It is shown that such a satellite system through multiple beam antennas and frequency reuse can provide thousands of radiotelephone and dispatch channels serving hundreds of thousands of users throughout the U.S.

Naderi, F. (editor)

1982-01-01

343

Considerations for NATO satellite communications in the post-2000 era  

NASA Astrophysics Data System (ADS)

The National Delegates Board of AGARD, upon recommendation by the Avionics Panel of AGARD, approved in March 1986 the establishment of WG-13 to study satellite communications for NATO under the direction of Prof. Dr. Nejat Ince of Turkey. Some 14 scientists/engineers, from research and industrial establishments of Canada, France, the Federal Republic of Germany, Norway, Turkey, the United Kingdom, the United States of America as well as from International Military Staff of NATO and SHAPE Technical Centre, participated in the work of WG-13. This paper is a brief summary of the studies carried out by the group in the period 1988-1990 on the type of satellite communication systems which NATO can have in the post-2000 era including the critical techniques and technologies that need to be developed for this purpose.

Ince, A. Nejat

1993-02-01

344

Medical image transmission via communication satellite: evaluation of ultrasonographic images.  

PubMed

As compared with terrestrial circuits, communication satellites possess superior characteristics such as wide area coverage, broadcasting functions, high capacity, and resistance to disasters. Utilizing the narrow band channel (64 kbps) of the stationary communication satellite JCSAT1 located at an altitude of 36,000 km above the equator, we investigated satelliterelayed dynamic medical images transmitted by video signals, using hepatic ultrasonography as a model. We conclude that the "variable playing speed transmission scheme" proposed by us is effective for the transmission of dynamic images in the narrow band channel. This promises to permit diverse utilization and applications for purposes such as the transmission of other types of ultrasonic images as well as remotely directed medical diagnosis and treatment. PMID:8916265

Suzuki, H; Horikoshi, H; Shiba, H; Shimamoto, S

1996-01-01

345

Coherent versus noncoherent signaling for satellite-aided mobile communications  

NASA Technical Reports Server (NTRS)

The use of coherent versus noncoherent communications is an unresolved issue for the mobile satellite community. Should one select the more robust but less efficient noncoherent strategy for communications over satellite-aided mobile channels, or does the introduction of a space platform in the mobile link improve signal stability (both amplitude and phase) such that conventional coherent schemes become attractive? This publication tries to answer some of the questions by discussing the results from experiments using a coherent QPSK receiver. The issues discussed include items such as the measured performance in Rician fading, the link error floor in a fading environment, etc. The results are compared and contrasted with that of a noncoherent limiter/discriminator FM receiver.

Davarian, F.; Sumida, J.

1986-01-01

346

AIAA International Communication Satellite Systems Conference and Exhibit, 14th, Washington, DC, Mar. 22-26, 1992, Technical Papers. Pts. 1-3  

SciTech Connect

The present conference on international communication satellite systems discusses GEO launch vehicle development, military Satcom systems, GEO mobile Satcom systems, advanced transponder technology, and digital network architecture. Attention is given to digital network architecture, the optical Satcom system, emerging launch alternatives, military and government Satcom systems, satellite communications developments in newly industrialized nations, launch options to nongeostationary orbits, and data relay satellite technology. Topics addressed include LEO satellite systems, earth terminal technology, personal communications, high data rate links via satellite, Italsat, antenna systems, Intelsat system and service development, new spacecraft system concepts, orbit/spectrum allocation and use, and ACTS technology. Also discussed are array antenna technology, VSAT and other small terminal systems, orbits, propagation, onboard satellite switching, reflector antenna technology, and panel small communication satellite systems.

Not Available

1992-01-01

347

Error control techniques for satellite and space communications  

NASA Technical Reports Server (NTRS)

Research activities related to error control techniques for satellite and space communication are reported. Specific areas of research include: coding gains for bandwidth efficient codes, hardware implementation of a bandwidth efficient coding scheme for the Hubble Space Telescope, construction of long trellis codes for use with sequential decoding, performance analysis of multilevel trellis codes, and M-algorithm decoding of trellis codes. Each topic is discussed in a corresponding paper that appears in the appendices.

Costello, Daniel J., Jr.

1991-01-01

348

Mechanical environmental test program for the Communications Technology Satellite  

NASA Technical Reports Server (NTRS)

This paper describes the spacecraft and subsystem level mechanical environmental test program which was developed for the Communications Technology Satellite (CTS). At the spacecraft level it includes sine and random vibration, static loading, centrifuge loading, pyrotechnic and separation shock simulation and (tentatively) acoustics. At the subsystem level it entails the same type of environmental exposure as applicable. Matrices of system and subsystem tests are presented showing type, level and hardware status for each major test.

Buckingham, R.; Sharp, G. R.

1974-01-01

349

A LEO concept for millimeter wave satellite communication  

NASA Technical Reports Server (NTRS)

A conceptual 60 satellite LEO constellation for millimeter wave communication is discussed. It could be launched in segments, with the first 30 satellites providing high elevation angles for all time in the Northern latitudes between Miami and Thule. The second set of 30 satellites would complete the worldwide coverage with emphasis on high ground elevation angles in the densely populated temperate zones. Full earth searches for all time are used to generate probability density functions for elevation angle. The density functions are used to derive optimum frequencies for random elevation systems. The 55 degree average elevation angle and 14 degree standard deviation are seen to be acceptable for 0.997 rain availability in Washington, DC for the 40 to 47 GHz region. The 40 to 47 GHz region is nearly optimum, if 0.99 rain availability is acceptable.

Jackson, A. H.; Christopher, P.

1995-01-01

350

Electric Propulsion for Low Earth Orbit Communication Satellites  

NASA Technical Reports Server (NTRS)

Electric propulsion was evaluated for orbit insertion, satellite positioning and de-orbit applications on big (hundreds of kilograms) and little (tens of kilograms) low earth orbit communication satellite constellations. A simple, constant circumferential thrusting method was used. This technique eliminates the complex guidance and control required when shading of the solar arrays must be considered. Power for propulsion was assumed to come from the existing payload power. Since the low masses of these satellites enable multiple spacecraft per launch, the ability to add spacecraft to a given launch was used as a figure of merit. When compared to chemical propulsion ammonia resistojets, ion, Hall, and pulsed plasma thrusters allowed an additional spacecraft per launch Typical orbit insertion and de-orbit times were found to range from a few days to a few months.

Oleson, Steven R.

1997-01-01

351

The 30/20 GHz communications satellite trunking network study  

NASA Technical Reports Server (NTRS)

Alternative transmission media for a CONUS-wide trunking network in the years 1990 and 2000 are examined. The alternative technologies comprised fiber optic cable, conventional C- and Ku-band satellites, and 30/20 GHz satellites. Three levels of implementation were considered - a 10-city network, a 20-city network, and a 40-city network. The cities selected were the major metropolitan areas with the greatest communications demand. All intercity voice, data, and video traffic carried more than 40 miles was included in the analysis. In the optimized network, traffic transmitted less than 500 miles was found to be better served by fiber optic cable in 1990. By the year 2000, the crossover point would be down to 200 miles, assuming availability of 30/20 GHz satellites.

Kolb, W.

1981-01-01

352

Open-loop nanosecond-synchronization for wideband satellite communications  

NASA Technical Reports Server (NTRS)

A synchronization technique for use with an onboard processing satellite communication system is discussed. The satellite oscillator is used both as the system time reference and as the frequency source for all downlink carriers and data clocks. Downlink timing is established at each system earth terminal through a combination of carrier and data-clock tracking and a downlink timing epoch signal consisting of one bit per TDMA data burst. Uplink timing is established by an open-loop range prediction process using precision ephemerides calculated and distributed by the central control station. Overall timing accuracy of the uplink signal at the satellite receiver of + or - 7 nanoseconds permits unambiguous identification of each data bit position in a 128 Mbps TDMA burst. This is accomplished by means of simple, inexpensive terminal hardware using available crystal oscillators for time/frequency references and digital synthesis techniques that may be implemented in digital LSI chips.

Holmes, W. M., Jr.

1980-01-01

353

Proceedings of the Advanced Communications Technology Satellite (ACTS) Conference 2000  

NASA Technical Reports Server (NTRS)

The ACTS experiments program, which began in December 1993 and consisted of 103 different experiments, has made significant contributions to minimizing the risk of advanced satellite communications technology. The ACTS Conference 2000 (AC2000) was held to report the results of the program since the last ACTS conference was held in 1995 and to celebrate the end of a very successful satellite program. The conference was held on May 31, 2000, as part of the 6th Ka-band Utilization Conference in Cleveland, Ohio. Approximately 280 representatives of industry, academia, and government attended. The conference was organized into two parts: a technical session during the day and an evening reception. During the day, a series of five technical sessions included presentations of 17 papers covering the results of the experiment activity and technical performance of the satellite. In the evening, a reception was held to celebrate the end of the ACTS Experiments Program on one of NASA's most successful experimental communications satellite. These proceedings were developed to capture the entire event, including the evening reception.

Bauer, Robert (Editor); Derwae, Robert (Editor)

2000-01-01

354

The current status of Russian/CIS communication satellites  

NASA Astrophysics Data System (ADS)

As part of a Memorandum of Understanding (MOU) signed by U.S. President George Bush and Russian President Mikhail Gorbackev during a July 1991 summit meeting, the U.S. agreed to expand civil space cooperation with the Russian Federation and the Commonwealth of Independent States (CIS). The goal of the MOU was to increase the technical capabilities of both sides to respond to both natural and man-made disasters and top benefit from the capabilities and involvement of international and non-government organizations. This summit agreement has allowed the Russian Federation to offer unprecedented commercial and emergency relief access to their on-orbit communications satellites. This thesis presents a brief history of the Soviet/Russian communication satellite program, and an examination of current systems as well as future and on-order systems. Simulations were conducted to determine the useability of the major systems (Gorizont, Ekran, Molniya, and Raduga) from 17 geographic locations. This is concluded with an introduction to the Telemedicine Space-bridge Project that is a direct result of the Bush-Gorbachev summit, and a shining example of Russian/U.S. cooperation in the satellite communication arena.

Ninas, Larry E.

1994-09-01

355

Satellite services system analysis study. Volume 5: Programmatics  

NASA Technical Reports Server (NTRS)

The overall program and resources needed for development and operation of a Satellite Services System is reviewed. Program requirements covered system operations through 1993 and were completed in preliminary form. Program requirements were refined based on equipment preliminary design and analysis. Schedules, costs, equipment utilization, and facility/advanced technology requirements were included in the update. Equipment user charges were developed for each piece of equipment and for representative satellite servicing missions.

1981-01-01

356

An assessment of the status and trends in satellite communications 1986-2000: An information document prepared for the Communications Subcommittee of the Space Applications Advisory Committee  

NASA Technical Reports Server (NTRS)

This is a response to a Space Applications Advisory Committee (SAAC) request for information about the status and trends in satellite communications, to be used to support efforts to conceive and recommend long range goals for NASA communications activities. Included in this document are assessments of: (1) the outlook for satellite communications, including current applications, potential future applications, and impact of the changing environment such as optical fiber networks, the Integrated Services Digital Network (ISDN) standard, and the rapidly growing market for Very Small Aperture Terminals (VSAT); (2) the restrictions imposed by our limited spectrum resource; and (3) technology needs indicated by future trends. Potential future systems discussed include: large powerful satellites for providing personal communications; VSAT compatible satellites with onboard switching and having voice capability; large satellites which offer a pervasive T1 network service (primarily for video-phone); and large geostationary communications facilities which support common use by several carriers. Also, discussion is included of NASA particular needs and possible future systems. Based on the mentioned system concepts, specific technology recommendations are provided for the time frames of now - 1993, 1994 - 2000, and 2000 - 2010.

Poley, W. A.; Stevens, G. H.; Stevenson, S. M.; Lekan, J.; Arth, C. H.; Hollansworth, J. E.; Miller, E. F.

1986-01-01

357

Land Mobile Satellite Service (LMSS): A conceptual system design and identification of the critical technologies. Part 1: Executive summary  

NASA Technical Reports Server (NTRS)

A system design for a satellite aided land mobile service is described. The advanced system is based on a geostationary satellite which employs a large UHF reflector to communicate with small user antennas on mobile vehicles. It is shown that the system through multiple beam antennas and frequency reuse provides for radiotelephone and dispatch channels. It is concluded that the system is technologically feasible to provide service to rural and remote regions.

Naderi, F. (editor)

1982-01-01

358

Satellite Communications for Aeronautics Applications: Technology Development and Demonstration  

NASA Technical Reports Server (NTRS)

The National Aeronautics and Space Administration (NASA) is performing research and development to improve the safety and increase the capacity of the National Airspace System (NAS). Improved communications, especially to and from the aircraft flight deck, has been identified as an essential enabling technology for future improvements to the air traffic management system and aviation safety. NASA's Glenn Research Center is engaged in research and development of satellite communications technologies for aeronautical applications. A mobile aero terminal has been developed for use with Ku band commercial communications satellites. This experimental terminal will be used in mobile ground and air-based tests and demonstrations during 2000-2004. This paper will describe the basic operational parameters of the Ku Band aero terminal, the communications architecture it is intended to demonstrate, and the key technology issues being addressed in the tests and demonstrations. The design of the Ku Band aero terminal and associated ground testbed, planned tests and demonstrations, and results to date will be presented.

Kerczewski, Robert J.; Hoder, Douglas J.; Zakrajsek, Robert J.

2001-01-01

359

David Florida Laboratory: Support for mobile satellite communications  

NASA Technical Reports Server (NTRS)

The comprehensive integration and environmental (including RF) test facilities of the Canadian Space Agency's David Florida Laboratory (CSA)(DFL) were used extensively for the MSAT Program. Following a description of the facilities, the paper outlines their application to the qualification of the two MSAT satellites following an overview of the test plan. Particular emphasis is given to passive intermodulation measurement (PIM) demands, which for the MSAT satellites, contributed to the need to extend the anechoic chamber. The extended chamber was also used for an EMC test and SAR signature test of the RADARSAT satellite. The DFL's facilities are being used for additional aspects of mobile satellite communications. One shielded anechoic Extra High Frequency (EHF) chamber and associated test equipment are employed predominantly for measuring the performance of the IRIDIUM satellites' Engineering Model Gateway Moveable Antennas (EM)(GMA). Other chambers are used for testing aeronautical antennas on behalf of Inmarsat. Still others combine thermal and PIM testing. The paper concludes with a review of the test requirements of evolving satcom missions such as Inmarsat Aero-1.

Dumoulin, Jean-Guy; Mamen, Rolf

1995-01-01

360

Requirements for a mobile communications satellite system. Volume 1: Executive summary  

NASA Technical Reports Server (NTRS)

Three types of satellite-aided mobile communications are considered for users in areas not served by (terrestrial) cellular radio systems. In System 1, mobile units are provided a direct satellite link to a gateway station, which serves as the interface to the terrestrial toll network. In System 2, a terrestrial radio link similar to those in cellular systems connects the mobile unit to a translator station; each translator relays the traffic from mobile units in its vicinity, via satellite, to the regional gateway. It is not feasible for System 2 to provide ubiquitous coverage. Therefore, System 3 is introduced, in which the small percentage of users not within range of a translator are provided a direct satellite link as in System 1. While System 2 can operate with leased satellite capacity, Systems 1 and 3 require a dedicated satellite. A major portion of this study is concerned with the design of a satellite for System 1. A weight limit of 10,000 lbs, corresponding to the projected 1990 STS capability, is imposed on the design. Frequency re-use of the allocated spectrum, through multiple satellite beams, is employed to generate the specified system capacity. Both offset-fed and center-fed reflectors are considered. For an assumed 10-MHz allocation and a population of 350,000 subscribers, a two-satellite system is required. The reflector diameters corresponding to offset-fed and center-fed geometries are 46 m and 62 m, respectively. Thus, large-space-structure technology is inherent to the implementation of System 1. In addition to establishing the technical requirements for the three types of satellite systems, the monthly service charge needed to provide a specified return on invested capital is computed. A net present value analysis is used for this purpose.

1983-01-01

361

The link evaluation terminal for the advanced communications technology satellite experiments program  

NASA Astrophysics Data System (ADS)

The experimental NASA satellite, Advanced Communications Technology Satellite (ACTS), introduces new technology for high throughput 30 to 20 GHz satellite services. Contained in a single communication payload is both a regenerative TDMA system and multiple 800 MHz 'bent pipe' channels routed to spot beams by a switch matrix. While only one mode of operation is typical during any experiment, both modes can operate simultaneously with reduced capability due to sharing of the transponder. NASA-Lewis instituted a ground terminal development program in anticipation of the satellite launch to verify the performance of the switch matrix mode of operations. Specific functions are built into the ground terminal to evaluate rain fade compensation with uplink power control and to monitor satellite transponder performance with bit error rate measurements. These functions were the genesis of the ground terminal's name, Link Evaluation Terminal, often referred to as LET. Connectors are included in LET that allow independent experimenters to run unique modulation or network experiments through ACTS using only the RF transmit and receive portions of LET. Test data indicate that LET will be able to verify important parts of ACTS technology and provide independent experimenters with a useful ground terminal. Lab measurements of major subsystems integrated into LET are presented. Bit error rate is measured with LET in an internal loopback mode.

May, Brian D.

1992-01-01

362

The Link Evaluation Terminal for the Advanced Communications Technology Satellite Experiments Program  

NASA Astrophysics Data System (ADS)

The experimental NASA satellite, Advanced Communications Technology Satellite (ACTS), introduces new technology for high throughput 30 to 20 GHz satellite services. Contained in a single communication payload is both a regenerative TDMA system and multiple 800 MHz 'bent pipe' channels routed to spot beams by a switch matrix. While only one mode of operation is typical during any experiment, both modes can operate simultaneously with reduced capability due to sharing of the transponder. NASA-Lewis instituted a ground terminal development program in anticipation of the satellite launch to verify the performance of the switch matrix mode of operations. Specific functions are built into the ground terminal to evaluate rain fade compensation with uplink power control and to monitor satellite transponder performance with bit error rate measurements. These functions were the genesis of the ground terminal's name, Link Evaluation Terminal, often referred to as LET. Connectors are included in LET that allow independent experimenters to run unique modulation or network experiments through ACTS using only the RF transmit and receive portions of LET. Test data indicate that LET will be able to verify important parts of ACTS technology and provide independent experimenters with a useful ground terminal. Lab measurements of major subsystems integrated into LET are presented. Bit error rate is measured with LET in an internal loopback mode.

May, Brian D.

1992-03-01

363

System design for the digitally implemented communications experiment /DICE/. [Communications Technology Satellite television for teleconferencing  

NASA Technical Reports Server (NTRS)

Full-duplex digital television providing a teleconference capability is to be evaluated in an experimental program utilizing the Communications Technology Satellite. The digitally implemented communications experiment employs a QPSK modulator-demodulator capable of operation over a wide range of bit rates. In addition to simultaneous data transmission (used for digital high-speed facsimiles and remote computer terminals), voice transmission through four-to-one compression will be studied.

Gatfield, A. G.; Suyderhoud, H. G.; Wolejsza, C. J., Jr.

1977-01-01

364

Technical characteristics of the OmniTRACS: The first operation mobile Ku-band satellite communications system  

NASA Technical Reports Server (NTRS)

The techinical characteristics of the OmniTRACS system are described. The system is the first operational mobile Ku-band satellite communications system and provides two-way message and position determination service to mobile terminals using existing Ku-band satellites. Interference to and from the system is minimized by the use of special spread-spectrum techniques, together with low power and low data rate transmissions.

Antonio, Franklin P.; Gilhousen, Klein S.; Jacobs, Irwin M.; Weaver, Linday A., Jr.

1988-01-01

365

Performance of an Integrated Voice\\/Data System in Nonuniform Traffic Low Earth-Orbit Satellite Communication Systems  

Microsoft Academic Search

In some recent studies, the use of low Earth-orbit satellites in various applications is considered. In all of these studies, uniform distribution of traffic load is assumed. In this paper, the performance of a low Earth-orbit satellite communication system which is designed to service to two kinds of users; i.e., voice users and data users is estimated. The distribution of

Abbas Jamalipour; Masaaki Katayama; Takaya Yamazato; Akira Ogawa

1995-01-01

366

Hybrid Global Communication Architecture with Balloons and Satellites  

NASA Astrophysics Data System (ADS)

Global space communication systems have been developed now for more than three decades, based mainly on geostationary satellites or almost equivalent systems such as the Molnya orbit concepts. The last decade of the twentieth century has seen the emergence of satellite constellations in low or medium Earth orbit, in order to improve accessibility in terms of visibility at higher latitudes and limited size or power requirement for ground equipment. However such systems are complex to operate, there are still many situations where connection may remain difficult to achieve, and commercial benefits are still to be proven. A new concept, using a network combination of geostationary relay satellites and high altitude stratospheric platforms may well overcome the inconveniences of both geostationary systems and satellite constellations to improve greatly global communication in the future. The emergence of enabling technologies developed in Japan and in several other countries will soon make it possible to fly helium balloons in the upper layers of the atmosphere, at altitudes of 20 km or more. At such an altitude, well above the meteorological disturbances and the jet-streams, the stratosphere enjoys a regular wind at moderate speeds ranging between 10 m/s and 30 m/s, depending on latitude and also on season. It is possible for balloons powered by electric engines to fly non- stop upstream of the wind in order to remain stationary above a particular location. Large balloons, with sizes up to 300 m in length, would be able to carry sub-satellite communication payloads, as well as observation apparatus and scientific equipment. The range of visibility for easy both-way communication between the balloon and operators or customers on the ground could be as large as 200 km in radius. Most current studies consider a combination of solar cells and storage batteries to power the balloons, but microwave beam wireless power transportation from the ground could be a very attractive alternative. A fleet of stratospheric balloons could cover the communication needs of all the major economic centres around the Earth, at unit costs that would be only a fraction of the current satellite systems that could serve the same needs. It will be possible to interconnect all the balloons through a handful of geostationary relay satellites. Because the balloons will be in ever-clear atmosphere, without fear of rain or cloud attenuation, it will be possible to use very high frequencies in the range of 60 GHz to 100 GHz, or even laser link systems, between the geostationary satellites and the balloons. There are many developments that need to be made to achieve operational systems, some requiring extended study and testing, such as handling very large balloons in the lower parts of the atmosphere during launch, designing industry-rated energy beam systems, maintaining the balloons for continuous operation over years or decades. But at the beginning of the 21st century, it appears that all these challenges may be met to offer Mankind the most efficient global communication system so far.

Pignolet, G.; Celeste, A.; Erb, B.

2002-01-01

367

Intersatellite Link (ISL) application to commercial communications satellites. Volume 2: Technical final report  

NASA Technical Reports Server (NTRS)

Intersatellite Link (ISL) applications can improve and expand communication satellite services in a number of ways. As the demand for orbital slots within prime regions of the geostationary arc increases, attention is being focused on ISLs as a method to utilize this resource more efficiently and circumvent saturation. Various GEO-to-GEO applications were determined that provide potential benefits over existing communication systems. A set of criteria was developed to assess the potential applications. Intersatellite link models, network system architectures, and payload configurations were developed. For each of the chosen ISL applications, ISL versus non-ISL satellite systems architectures were derived. Both microwave and optical ISL implementation approaches were evaluated for payload sizing and cost analysis. The technological availability for ISL implementations was assessed. Critical subsystems technology areas were identified, and an estamate of the schedule and cost to advance the technology to the requiered state of readiness was made.

Young, S. Lee

1987-01-01

368

Digital sound service for direct broadcasting satellites  

NASA Astrophysics Data System (ADS)

A 16 channel (4 phase (CPSK), or 12 channel (2 phase CPSK) digital sound link for the TV Sat satellite is proposed. Small parabolic antennas suitable for sound and TV broadcasts assure reception. A specially developed tuner allows the user to select either a given program from 1 of 16, or 1 of 8 types of program, e.g., sport or opera. Tests with OTS satellite and a cable distribution network prove the feasibility of the proposal. Encoding, transmission, signal modulation and links are outlined. Equipment is described.

Treytl, D.

369

The 30/20 Gigahertz transponder study. [wideband multichannel transponders for a communications satellite  

NASA Technical Reports Server (NTRS)

Design features and performance parameters are described for three types of wideband multiple channel satellite transponders for use in a 30/20 GHz communications satellite, which provides high data rate trunking service to ten ground station terminals. The three types of transponder are frequency division multiplex (FDM), time division multiplex (TDM), and a hybrid transponder using a combination of FDM and TDM techniques. The wideband multiple beam trunking concept, the traffic distribution between the trunking terminals, and system design constraints are discussed. The receiver front end design, the frequency conversion scheme, and the local oscillator design are described including the thermal interface between the transponders and the satellite. The three designs are compared with regard to performance, weight, power, cost and initial technology. Simplified block diagrams of the baseline transponder designs are included.

1980-01-01

370

An optimized bandwidth efficient demand assigned protocol for integrated Mobile Satellite Services  

NASA Technical Reports Server (NTRS)

This paper describes the design of a demand assigned protocol based on bandwidth efficiency for integrated services of a Mobile Satellite System (MSS). An MSS provides data (closed-ended) and voice (open-ended) communications services for a large number of mobile users dispersed over a wide geographical area. Each mobile requests its desired service through a designated set of channels to a network management center. Either pure or slotted ALOHA random access scheme can be used to make connection requests, while data and voice communications are demand assigned. All channels have equal bandwidth and can be adaptively used for reservation requests, data connections or voice connections to maximize the bandwidth utilization. In this paper, perfect communications channels are assumed. It has been shown that, for the case considered, using the slotted ALOHA scheme for making connection requests can save about 30 percent on the total number of channels over using the pure ALHOA scheme.

Yan, T.-Y.; Wang, C. C.

1985-01-01

371

Canadian development and commercialization of a North American mobile satellite service  

NASA Astrophysics Data System (ADS)

Canada recognized early the value of mobile satellite communications, originally through the planning of a military system and subsequently through the development of the Canadian Mobile Satellite (MSAT) systems. Acting on behalf of the government, the Department of Communications (DOC) defined and carried out a complete plan for the implementation of Mobile Satellite Services (MSS). Based on an extensive dialogue between government, industry, and users and encompassing all technical, economic regulatory, and institutional aspects, this plan resulted in the completion by 1986 of a comprehensive business plan and a decision for commercial MSS delivery. The Canadian lead for a commercial system was quickly followed by others, and in particular the U.S., giving rise to the concept of North American MSS.

Athanassiadis, Demetre

372

EUTELTRACS: The European experience on mobile satellite services  

NASA Technical Reports Server (NTRS)

EUTELTRACS is Europe's first commercially operated Mobile Satellite Service. Under the overall network operation of EUTELSAT, the European Telecommunications Satellite Organization, EUTELTRACS provides an integrated message exchange and position reporting service. This paper describes the EUTELTRACS system architecture, the message exchange and the position reporting services, including the result of recent analysis of message delivery time and positioning accuracy. It also provides an overview of the commercial deployment, the regulatory situation for its operation within Europe and new applications outside its target market, the international road transportation.

Colcy, Jean-Noel; Steinhaeuser, Rafael

1993-01-01

373

Satellite Servicing in Mission Design Studies at the NASA GSFC  

NASA Technical Reports Server (NTRS)

Several NASA missions in various stages of development have undergone one-week studies in the National Aeronautics and Space Administration (NASA) Goddard Space Flight Center (GSFC) Integrated Mission Design Center (IMDC), mostly in preparation for proposals. The possible role of satellite servicing has been investigated for several of these missions, applying the lessons learned from Hubble Space Telescope (HST) servicing, taking into account the current state of the art, projecting into the future, and implementing NASA long-range plans, and is presented here. The general benefits and costs of injecting satellite servicing are detailed, including components such as mission timeline, mass, fuel, spacecraft design, risk abatement, life extension, and improved performance. The approach taken in addressing satellite servicing during IMDC studies is presented.

Leete, Stephen J.

2003-01-01

374

Study of information transfer optimization for communication satellites  

NASA Technical Reports Server (NTRS)

The results are presented of a study of source coding, modulation/channel coding, and systems techniques for application to teleconferencing over high data rate digital communication satellite links. Simultaneous transmission of video, voice, data, and/or graphics is possible in various teleconferencing modes and one-way, two-way, and broadcast modes are considered. A satellite channel model including filters, limiter, a TWT, detectors, and an optimized equalizer is treated in detail. A complete analysis is presented for one set of system assumptions which exclude nonlinear gain and phase distortion in the TWT. Modulation, demodulation, and channel coding are considered, based on an additive white Gaussian noise channel model which is an idealization of an equalized channel. Source coding with emphasis on video data compression is reviewed, and the experimental facility utilized to test promising techniques is fully described.

Odenwalder, J. P.; Viterbi, A. J.; Jacobs, I. M.; Heller, J. A.

1973-01-01

375

High power microwave components for space communications satellite  

NASA Technical Reports Server (NTRS)

Analyzed, developed, and tested were high power microwave components for communications satellites systems. Included were waveguide and flange configurations with venting, a harmonic filter, forward and reverse power monitors, electrical fault sensors, and a diplexer for two channel simultaneous transmission. The assembly of 8.36 GHz components was bench tested, and then operated for 60 hours at 3.5 kW CW in a high vacuum. The diplexer was omitted from this test pending a modification of its end irises. An RF leakage test showed only that care is required at flange junctions; all other components were RF tight. Designs were extrapolated for 12 GHz and 2.64 GHz high power satellite systems.

Jankowski, H.; Geia, A.

1972-01-01

376

Enhanced TCP for maritime communications over satellite network  

NASA Astrophysics Data System (ADS)

For maritime communications over satellite network, TCP performance is essential for data transmissions. TCP ADaLR is congestion control algorithm that the sender judgments the relevant window change and measures roundtrip time to control congestion window. It can adapt to the characteristics of the satellite link and improve the performance of TCP than conventional TCP. However, it does not take into account distinction of random packet loss and congestion loss like TCP Veno. In this paper, we propose further enhancement of TCP ADaLR, called TCP ADaLR+, that can distinguish between random packet loss and congestion loss. The improved performance of proposed TCP ADaLR+ is demonstrated by simulations.

Zong, Liang; Du, Wencai; Bai, Yong

2014-10-01

377

Study of repeater technology for advanced multifunctional communications satellites  

NASA Technical Reports Server (NTRS)

Investigations are presented concerning design concepts and implementation approaches for the satellite communication repeater subsystems of advanced multifunctional satellites. In such systems the important concepts are the use of multiple antenna beams, repeater switching (routing), and efficient spectrum utilization through frequency reuse. An information base on these techniques was developed and tradeoff analyses were made of repeater design concepts, with the work design taken in a broad sense to include modulation beam coverage patterns. There were five major areas of study: requirements analysis and processing; study of interbeam interference in multibeam systems; characterization of multiple-beam switching repeaters; estimation of repeater weight and power for a number of alternatives; and tradeoff analyses based on these weight and power data.

1972-01-01

378

Chaos Based Secure IP Communications over Satellite DVB  

NASA Astrophysics Data System (ADS)

The Digital Video Broadcasting—Satellite (DVB-S) standard was originally conceived for TV and radio broadcasting. Later, it became possible to send IP packets using encapsulation methods such as Multi Protocol Encapsulation, MPE, or Unidirectional Lightweight Encapsulation, ULE. This paper proposes a chaos based security system for IP communications over DVB-S with ULE encapsulation. The proposed security system satisfies all the security requirements while respecting the characteristics of satellite links, such as the importance of efficient bandwidth utilization and high latency time. It uses chaotic functions to generate the keys and to encrypt the data. The key management is realized using a multi-layer architecture. A theoretical analysis of the system and a simulation of FTP and HTTP traffic are presented and discussed to show the cost of the security enhancement and to provide the necessary tools for security parameters setup.

Caragata, Daniel; El Assad, Safwan; Tutanescu, Ion; Sofron, Emil

2010-06-01

379

Future earth stations in 14-12 GHz for domestic satellite communications  

Microsoft Academic Search

More and more countries of the world are making plans to change over to higher frequency band of 14-12 GHz for satellite communications. This band is quite attractive for domestic satellite communications including TV broadcast as satellites with narrower beams and higher EIRPs have become realities. In this paper, present trends in technology at this frequency are reviewed in relation

N. Mohanty; S. Barathy; M. L. Hasija

1978-01-01

380

Low earth orbit satellite/terrestrial mobile service compatibility  

NASA Technical Reports Server (NTRS)

Digital cellular mobile 'second generation' systems are now gradually being introduced into service; one such example is GSM, which will provide a digital voice and data service throughout Europe. Total coverage is not expected to be achieved until the mid '90's, which has resulted in several proposals for the integration of GSM with a geostationary satellite service. Unfortunately, because terrestrial and space systems have been designed to optimize their performance for their particular environment, integration between a satellite and terrestrial system is unlikely to develop further than the satellite providing a back-up service. This lack of system compatibility is now being addressed by system designers of third generation systems. The next generation of mobile systems, referred to as FPLMTS (future public land mobile telecommunication systems) by CCIR and UMTS (universal mobile telecommunication system) in European research programs, are intended to provide inexpensive, hand-held terminals that can operate in either satellite, cellular, or cordless environments. This poses several challenges for system designers, not least in terms of the choice of multiple access technique and power requirements. Satellite mobile services have been dominated by the geostationary orbital type. Recently, however, a number of low earth orbit configurations have been proposed, for example Iridium. These systems are likely to be fully operational by the turn of the century, in time for the implementation of FPLMTS. The developments in LEO mobile satellite service technology were recognized at WARC-92 with the allocation of specific frequency bands for 'big' LEO's, as well as a frequency allocation for FPLMTS which included a specific satellite allocation. When considering integrating a space service into the terrestrial network, LEO's certainly appear to have their attractions: they can provide global coverage, the round trip delay is of the order of tens of milliseconds, and good visibility to the satellite is usually possible. This has resulted in their detailed investigation in the European COST 227 program and in the work program of the European Telecommunications Standards Institute (ETSI). This paper will consider the system implications of integrating a LEO mobile service with a terrestrial service. Results will be presented from simulation software to show how a particular orbital configuration affects the performance of the system in terms of area coverage and visibility to a terminal for various locations and minimum elevation angle. Possible network topologies are then proposed for an integrated satellite/terrestrial network.

Sheriff, R. E.; Gardiner, J. G.

1993-01-01

381

Facsimile transmission utilizing TDMA satellite service  

Microsoft Academic Search

In 1961, Dow Jones began printing The Wall Street Journal using high-speed facsimile scanners and recorders. High cost of transporting the papers to the customer was the motivating force, although the tradeoff was high lease cost of microwave facilities. In 1965, data compression techniques were applied to facsimile scanning and recording, reducing bandwidth requirements and lowering communications cost. Laboratory on-line

W. L. Dunn; G. C. Jenkins

1979-01-01

382

Transmitter experiment package for the communications technology satellite  

NASA Technical Reports Server (NTRS)

The operating requirements, system design characteristics, high voltage packaging considerations, nonstandard components development, and test results for the transmitter experiment package (TEP) are described. The TEP is used for broadcasting power transmission from the Communications Technology Satellite. The TEP consists of a 12 GHz, 200-watt output stage tube (OST), a high voltage processing system that converts the unregulated spacecraft solar array power to the regulated voltages required for OST operation, and a variable conductance heat pipe system that is used to cool the OST body.

Farber, B.; Goldin, D. S.; Marcus, B.; Mock, P.

1977-01-01

383

Why is CDMA the solution for mobile satellite communication  

NASA Technical Reports Server (NTRS)

It is demonstrated that spread spectrum Code Division Multiple Access (CDMA) systems provide an economically superior solution to satellite mobile communications by increasing the system maximum capacity with respect to single channel per carrier Frequency Division Multiple Access (FDMA) systems. Following the comparative analysis of CDMA and FDMA systems, the design of a model that was developed to test the feasibility of the approach and the performance of a spread spectrum system in a mobile environment. Results of extensive computer simulations as well as laboratory and field tests results are presented.

Gilhousen, Klein S.; Jacobs, Irwin M.; Padovani, Roberto; Weaver, Lindsay A.

1989-01-01

384

More About Lens Antenna For Mobile/Satellite Communication  

NASA Technical Reports Server (NTRS)

Report presents additional details of design of proposed phased-array antenna described in "Lens Antenna for Mobile/Satellite Communication" (NPO-16948). Intended to be compact and to lie flat on top of vehicle on ground. Transmits and receives circularly polarized radiation in frequency ranges of 821 to 825 MHz and 860 to 870 MHz. Transmitting and receiving beams electronically steerable to any of 48 evenly spaced directions to provide complete azimuth coverage, and would be fixed, but wide, in elevation, to provide coverage at elevation angles from 20 degrees to 60 degrees.

Rahmat-Samii, Y.; Bodnar, D. G.; Rainer, B. K.

1990-01-01

385

On-board packet switch architectures for communication satellites  

NASA Technical Reports Server (NTRS)

NASA Lewis Research Center is developing an on-board information switching processor for a multichannel communications signal processing satellite. The information switching processor is a flexible, high-throughput, fault tolerant, on-board baseband packet switch used to route user data among user ground terminals. Through industry study contracts and in-house investigations, several packet switching architectures were examined for possible implementation. Three contention-free switching architectures were studied in detail, namely the shared memory approach, the shared bus approach, and the shared memory per beam approach. These three switching architectures are discussed and the advantages and disadvantages of each approach are examined.

Shalkhauser, Mary JO; Quintana, Jorge A.

1993-01-01

386

A high gain antenna system for airborne satellite communication applications  

NASA Technical Reports Server (NTRS)

A high gain antenna for commercial aviation satellites communication is discussed. Electromagnetic and practical design considerations as well as candidate systems implementation are presented. An evaluation of these implementation schemes is given, resulting in the selection of a simple top mounted aerodynamic phased array antenna with a remotely located beam steering unit. This concept has been developed into a popular product known as the Canadian Marconi Company CMA-2100. A description of the technical details is followed by a summary of results from the first production antennas.

Maritan, M.; Borgford, M.

1990-01-01

387

Space Network IP Services (SNIS): An Architecture for Supporting Low Earth Orbiting IP Satellite Missions  

NASA Technical Reports Server (NTRS)

The NASA Space Network (SN) supports a variety of missions using the Tracking and Data Relay Satellite System (TDRSS), which includes ground stations in White Sands, New Mexico and Guam. A Space Network IP Services (SNIS) architecture is being developed to support future users with requirements for end-to-end Internet Protocol (IP) communications. This architecture will support all IP protocols, including Mobile IP, over TDRSS Single Access, Multiple Access, and Demand Access Radio Frequency (RF) links. This paper will describe this architecture and how it can enable Low Earth Orbiting IP satellite missions.

Israel, David J.

2005-01-01

388

On-orbit servicing for satellite upgrades  

E-print Network

Except for manned servicing operations using the Shuttle, there is no maintenance infrastructure for space systems. The traditional approach is to build in reliability and to replace the system in case of obsolescence or ...

Joppin, Carole, 1979-

2004-01-01

389

Demonstration of a Ka-Band communication path for On-Orbit Servicing  

NASA Astrophysics Data System (ADS)

The objectives of on-orbit servicing (OOS) missions include manipulation, proximity operations and inspection of target satellites. Therefore the servicer satellite often has to be teleoperated at low latency for several minutes to fulfill these tasks. That means communication plays a crucial role for OOS missions because real time teleoperation including high data rates has to be realized. So the communication path from front end sensors on the servicer spacecraft to the operator on ground has to be optimized and the latency time has to be minimized. Furthermore a long access time from the ground station is required because continuous communication with the satellite is mandatory for most of the OOS tasks. This can be realized by an inter-satellite link via a geostationary relay satellite, which has the advantage that a satellite in Low Earth Orbit (LEO) can be accessed from one ground station for about half an orbit. To evaluate both, the requirement of a long access time from the ground station as well as the need of a short latency time, an end to end communication scenario was implemented at the Institute of Astronautics (LRT) at the Technische Universität München (TUM). This scenario includes different spacecraft sensors (e.g. stereo cameras, LIDAR systems), a Ka-Band ground station and man machine interfaces. This paper describes the setup of a realistic simulation of a communication path from a data source to an operator via space-link. Furthermore the method of latency measuring depending on the data source is described. The communication architecture is embedded in a spacecraft simulator to simulate On-Orbit Servicing scenarios like Space Debris removal and target inspection.

Purschke, R.; Harder, J.; Fleischner, A.

2011-09-01

390

Low and Medium-Gain antennas for Mobile Satellite Communications (MSC) and Navigation  

Microsoft Academic Search

In this paper are introduced Low-Gain Omnidirectional Antennas for Mobile Satellite Communications (MSC) and Navigation. In many respects the Mobile Satellite Antenna (MSA) infrastructures currently available for MSC and Navigation. Medium and high gain MSA need to track the satellite, following both movements of mobiles and satellite orbital motions. Sometimes this is difficult and expensive to synchronize and have to

Stojce Dimov Ilcev

2011-01-01

391

WORLD DATA SERVICES Iridium Satellite LLC Rev. 2; June 15, 2001  

E-print Network

WORLD DATA SERVICES Overview Iridium Satellite LLC Rev. 2; June 15, 2001 #12;IRIDIUM WORLD DATA Introduction to Iridium World Data Services............................................................................................ 6 Iridium Satellite LLC 2 Rev. 2; June 15, 2001 #12;IRIDIUM WORLD DATA SERVICES

Ashley, Michael C. B.

392

Next generation communications satellites: Multiple access and network studies  

NASA Technical Reports Server (NTRS)

Following an overview of issues involved in the choice of promising system architectures for efficient communication with multiple small inexpensive Earth stations serving hetergeneous user populations, performance evaluation via analysis and simulation for six SS/TDMA (satellite-switched/time-division multiple access) system architectures is discussed. These configurations are chosen to exemplify the essential alternatives available in system design. Although the performance evaluation analyses are of fairly general applicability, whenever possible they are considered in the context of NASA's 30/20 GHz studies. Packet switched systems are considered, with the assumption that only a part of transponder capacit is devoted to packets, the integration of circuit and packet switched traffic being reserved for further study. Three types of station access are distinguished: fixed (FA), demand (DA), and random access (RA). Similarly, switching in the satellite can be assigned on a fixed (FS) or demand (DS) basis, or replaced by a buffered store-and-forward system (SF) onboard the satellite. Since not all access/switching combinations are practical, six systems are analyzed in detail: three FS SYSTEMS, FA/FS, DA/ES, RA/FS; one DS system, DA/DS; and two SF systems, FA/SF, DA/SF. Results are presented primarily in terms of delay-throughput characteristics.

Stern, T. E.; Schwartz, M.; Meadows, H. E.; Ahmadi, H. K.; Gadre, J. G.; Gopal, I. S.; Matsmo, K.

1980-01-01

393

Operating frequencies for educational satellite services  

NASA Technical Reports Server (NTRS)

The factors affecting the choice of transmission frequencies are identified. These include international radio regulations, natural environment, man-made environment, hardware considerations, and interconnection and spectrum space considerations. An analysis is presented of international radio regulations with emphasis on 1963 EARC and 1971 WARC frequency allocations, powerflux density restrictions, and resolutions concerning introduction of broadcasting-satellite systems. Natural-environmental effects were divided into two categories: (1) those due to transionospheric propagation, and (2) those that can be credited to the earth's atmosphere and its constituents. The frequency dependence of the signal attenuation, signal distortion, and contributions to system noise temperature due to environmental effects are discussed, and comparisons were made for frequencies of interest. Man-made environmental effects were examined in terms of various sharing limitations as well as the indigenous noise contribution to the overall system noise.

Singh, J. P.

1971-01-01

394

The 30/20 GHz fixed communications systems service demand assessment. Volume 1: Executive summary  

NASA Technical Reports Server (NTRS)

Demand for telecommunications services is forecasted for the period 1980-2000, with particular reference to that portion of the demand associated with satellite communications. Overall demand for telecommunications is predicted to increase by a factor of five over the period studied and the satellite portion of demand will increase even more rapidly. Traffic demand is separately estimated for voice, video, and data services and is also described as a function of distance traveled and city size. The satellite component of projected demand is compared with the capacity available in the C and Ku satellite bands and it is projected that new satellite technology and the implementation of Ka band transmission will be needed in the decade of the 1990's.

Gamble, R. B.; Seltzer, H. R.; Speter, K. M.; Westheimer, M.

1979-01-01

395

Mobile satellite services for public safety, disaster mitigation and disaster medicine  

NASA Astrophysics Data System (ADS)

Between 1967 and 1987 nearly three million lives were lost and property damage of $25 to $100 billion resulted form natural disasters that adversely affected more than 829 million people. The social and economic impacts have been staggering and are expected to grow more serious as a result of changing demographic factors. The role that the Mobile Satellite Service can play in the International Decade is discussed. MSS was not available for disaster relief operations during the recent Loma Prieta/San Francisco earthquake. However, the results of a review of the performance of seven other communication services with respect to public sector operations during and shortly after the earthquake are described. The services surveyed were: public and private telephone, mobile radio telephone, noncellular mobile radio, broadcast media, CB radio, ham radio, and government and nongovernment satellite systems. The application of MSS to disaster medicine, particularly with respect to the Armenian earthquake is also discussed.

Freibaum, Jerry

396

Mobile satellite services for public safety, disaster mitigation and disaster medicine  

NASA Technical Reports Server (NTRS)

Between 1967 and 1987 nearly three million lives were lost and property damage of $25 to $100 billion resulted form natural disasters that adversely affected more than 829 million people. The social and economic impacts have been staggering and are expected to grow more serious as a result of changing demographic factors. The role that the Mobile Satellite Service can play in the International Decade is discussed. MSS was not available for disaster relief operations during the recent Loma Prieta/San Francisco earthquake. However, the results of a review of the performance of seven other communication services with respect to public sector operations during and shortly after the earthquake are described. The services surveyed were: public and private telephone, mobile radio telephone, noncellular mobile radio, broadcast media, CB radio, ham radio, and government and nongovernment satellite systems. The application of MSS to disaster medicine, particularly with respect to the Armenian earthquake is also discussed.

Freibaum, Jerry

1990-01-01

397

European Mobile Satellite Services (EMSS): A regional system for Europe  

NASA Technical Reports Server (NTRS)

The European Space Agency is presently procuring two L-band payloads in order to promote a regional system for the provision of European Mobile Satellite Services (EMSS). These are the EMS payload on the Italsat I-F2 satellite and the LLM payload on the ARTEMIS satellite. Telecommunication system studies have been concentrating on mobile applications where full European geographical coverage is required. Potential applications include high priority Private Mobile Radio networks requiring national or European coverage, such as civil security, fire brigades, police and health services, as well as a dedicated system for provision of Air Traffic Services to the civil aviation community. A typical application is an intelligent road traffic management system combining a geographically selective traffic data collection service based on probe vehicles with a geographically selective traffic information broadcast service. Network architectures and bearer services have been developed both for data only and voice/data services. Vehicle mounted mobile transceivers using CDMA access techniques have been developed. The EMSS operational phase will start with the EMS payload in orbit in 1996 and continue with the LLM payload in 1997.

Loisy, C.; Edin, P.; Benedicto, F. J.

1995-01-01

398

NASA satellite communications application research. Phase 2: Efficient high power, solid state amplifier for EFH communications  

NASA Technical Reports Server (NTRS)

The final report describes the work performed from 9 Jun. 1992 to 31 Jul. 1993 on the NASA Satellite Communications Application Research (SCAR) Phase 2 program, Efficient High Power, Solid State Amplifier for EHF Communications. The purpose of the program was to demonstrate the feasibility of high-efficiency, high-power, EHF solid state amplifiers that are smaller, lighter, more efficient, and less costly than existing traveling wave tube (TWT) amplifiers by combining the output power from up to several hundred solid state amplifiers using a unique orthomode spatial power combiner (OSPC).

Benet, James

1993-01-01

399

Status of NASA's Assessment of Satellite Servicing  

NASA Technical Reports Server (NTRS)

Following recommendations by the National Research Council, NASA's Authorization Act of 2008 (P.I. 110-422) and the Fiscal Year 2009 Omnibus Appropriations Act directed NASA to assess the feasibility of using the planned human spaceflight architecture to service existing and future observatory-class scientific spacecraft. This interest in space servicing, either with astronauts and/or with robots, reflects the decades-long success that NASA has achieved with the Space Shuttle program and the Hubble Space Telescope on behalf of the international astronomical community. This study is led by NASA Goddard Space Flight Center and will last about a year, leading to an assessment report to NASA and the science communities. We will report on the status of this study, progress toward goals, workshops, and priorities for the next few months.

Thronson, H. A.; Ahmed, M.; Townsend, J.; Whipple, A. L.; Oegerle, W. R.

2010-01-01

400

Evaluation of spacecraft technology programs (effects on communication satellite business ventures), volume 2  

NASA Technical Reports Server (NTRS)

The computational procedures used in the evaluation of spacecraft technology programs that impact upon commercial communication satellite operations are discussed. Computer programs and data bases are described.

Greenburg, J. S.; Kaplan, M.; Fishman, J.; Hopkins, C.

1985-01-01

401

The AMSC/TMI mobile satellite services (MSS) system ground segment architecture  

NASA Astrophysics Data System (ADS)

The functional structure and logical architecture of the ground segment for the MSS system is examined. The functional structure describes the functional elements of the system and how they are interconnected. These include the network operations center, network communications controller, feederlink earth stations, data hub, mobile terminals, remote monitor stations, and the system test station. The logical architecture, implemented within the functional structure, describes the logical elements of the MSS system and how they are interrelated. These include resource partitioning and management, network management, user communications, and MSS internetwork communications. The NCS manages the allocation of satellite resources to provide communications services between the mobile terminals and feederlink earth stations or the data hub.

Lunsford, J.; Thorne, R.; Gokhale, D.; Garner, W.; Davies, G.

1992-03-01

402

Customer premise service study for 30/20 GHz satellite system  

NASA Technical Reports Server (NTRS)

Satellite systems in which the space segment operates in the 30/20 GHz frequency band are defined and compared as to their potential for providing various types of communications services to customer premises and the economic and technical feasibility of doing so. Technical tasks performed include: market postulation, definition of the ground segment, definition of the space segment, definition of the integrated satellite system, service costs for satellite systems, sensitivity analysis, and critical technology. Based on an analysis of market data, a sufficiently large market for services is projected so as to make the system economically viable. A large market, and hence a high capacity satellite system, is found to be necessary to minimize service costs, i.e., economy of scale is found to hold. The wide bandwidth expected to be available in the 30/20 GHz band, along with frequency reuse which further increases the effective system bandwidth, makes possible the high capacity system. Extensive ground networking is required in most systems to both connect users into the system and to interconnect Earth stations to provide spatial diversity. Earth station spatial diversity is found to be a cost effective means of compensating the large fading encountered in the 30/20 GHz operating band.

Milton, R. T.; Ross, D. P.; Harcar, A. R.; Freedenberg, P.; Schoen, D.

1983-01-01

403

Rearrangement procedures in regenerative multibeammobile communications satellites with frequency reuse  

NASA Technical Reports Server (NTRS)

After a short overview on the European tendencies about a Land Mobile Satellite Service, this paper describes an advanced system architecture, based on multiple spot-beams and on-board processing, capable of providing message and voice services over a wide European coverage, including some North-Africa and Middle-East countries. A remarkable problem associated with spot-beam configurations is the requirement for flexibility in the capacity offer to the various coverage areas. This means incorporating procedures for changing the on-board modulator-to-spot associations, respecting the constraints imposed by frequency reuse. After discussing the requirements of the rearrangement procedure, an on-purpose algorithm is presented. This paper is derived from work performed on contract to the European Space Agency (ESA).

Colombo, Gianni; Settimo, Franco; Vernucci, Antonio

1988-01-01

404

Third International Satellite Direct Broadcast Services User's Conference  

NASA Technical Reports Server (NTRS)

A workshop titled, The Third International Satellite Direct Broadcast Services User's Conference, jointly sponsored by NASA and NOAA/NESDIS was scheduled to be held June 20 to 24, 1988, at the International Hotel located at the Baltimore-Washington Airport. Details concerning the organizing of the conference are given.

Kamowski, J.; Vermillion, C.

1988-01-01

405

Olympus: Un satellite au service de l'education (Olympus: A Satellite in Service to Education).  

ERIC Educational Resources Information Center

Olympus, launched by Ariane in 1989, is the first European satellite to transmit an experimental educational and cultural program. The satellite is not only providing current programing but is testing the possibilities for distance education in the future. A schedule of humanities and science programing is presented. (MSE)

Lancien, Thierry

1990-01-01

406

Integration of mobile satellite service with advanced traffic management systems  

NASA Astrophysics Data System (ADS)

Mobile satellite communications systems are reviewed, and applications to the Intelligent Vehicle Highway System (IVHS) are described for the positioning and communications systems of the trucking industry. The advantages of the concept are set forth, and the components of mobile satellite system technologies are listed. Subscriber software and database access are discussed with respect to potential applications of the system including updating vehicle logs, translating driver messages, and checking vehicles. Computerized routing and vehicle tracking can be implemented with the system which would permit the optimization of routing in the trucking industry. The IVHS technologies contribute to four functional areas of traffic operations including traffic management, driver information, commercial vehicle operation, and advanced vehicle control systems.

Davis, Christopher L.

1991-04-01

407

Communication Satellite Technology and Multi-Media Demonstration on-Board ISS  

NASA Astrophysics Data System (ADS)

The paper presents ongoing preparative activities and the opportunities for a utilization of the European ISS Module COLUMBUS as a testbed for communications and multimedia technology. This can provide a new service to the commercially oriented Space Communication Community and Parties interested in tests of space bound terrestrial applications (e.g. telematics). For this purpose, Astrium SI, Bremen, has studied several options how to test and verify advanced Multi-Media / Broadband Communications of Non-Geostationary Systemes. These activities have been conducted in cooperation with, and/or under contract of, DLR and ESA/ESTEC. With an accordingly equipped platform on-board the European ISS Module COLUMBUS a generic test-bed for Multi- Media-Services, inter-orbit link technology and other to be verified and demonstrated technology may be derived. The advantages of such an universal test service are obvious: - Crew accessibility / maintainability - Return of hardware after test to earth possible - Exposure of equipment to space environment - Fast to be installed experiments (compared to satellite missions) - Reasonable effort by shared installation costs (esp. compared to GEO missions) This may result in a new kind of technology demo missions (e.g. commercial parts applications, experiments of to-the-need scalable duration etc.).

Anspach von Broecker, G. O.; Bank, C.; Kolloge, H.-G.; Brauer, U.; Canovai, G.; Keller, M.

2002-01-01

408

The EUTELSAT II satellites: Europe's seeds in communication and TV distribution game  

NASA Astrophysics Data System (ADS)

The state-of-the-art satellite EUTELSAT II, developed by Aerospatiale and its industrial partners, is designed to provide Ku-band communication and television distribution services with 16 active channels accessible simultaneously to all users over the whole of Europe. Reconfigurable antenna-feed networks permits zoom operation on all 16 channels offering enhanced EIRP over the central part of Europe for TV distribution purposes. The satellite is designed to be fully operational during eclipse and to be compatible with Ariane IV. High satellite reliability and availability are achieved by the use of 8/12 amplifier ring redundancy during and beyond the 7 year life. The payload design makes use of only two antennas for all communications transmit and receive functions. This resulted in a great simplification of the repeater configuration and provides operational flexibility. The platform is directly derived from the Aerospatiale-MBB Spacebus 100 family (Arabsat heritage). Aerospatiale Telecommunications Programme Office, located in Cannes (France) is the prime contractor of the industrial team, Aeritalia, ATES, CASA, Contraves, Crouzet, ERA, ETCA, MBB, MSS, SEP. First flight model delivery in November 1989 has been a key factor in shaping both technical and management approaches to the programme.

Burgio, C.; Soula, J. L.; Dumesnil, J. J.

409

Power processing system for a 200 watt communication satellite transmitter  

NASA Technical Reports Server (NTRS)

A power processing system (PPS) for a communication satellite, high power (200W RF) multi-stage depressed collector, 12 GHz, traveling wave tube, is described. The PPS converts spacecraft bus power at a nominal voltage of 76 Vdc to the levels necessary for operating a ten-collector coupled cavity TWT requiring approximately 500 watts of input power. Regulated voltages of up to -11.3K Vdc are provided along with command, protection and telemetry signal conditioning circuits. Power processor interface requirements are set forth and a block diagram illustrating the basic approach utilized is presented. Overall performance, design characteristics and unique features are discussed. Thermal and mechanical interface requirements impacting on PPS design are described as well as the thermal control technique utilized for the overall PPS/TWT assembly.

Farber, B. F.; Schoenfeld, A. D.; Thollot, P. A.

1975-01-01

410

Considerations of digital phase modulation for narrowband satellite mobile communication  

NASA Technical Reports Server (NTRS)

The Inmarsat-M system for mobile satellite communication is specified as a frequency division multiple access (FDMA) system, applying Offset Quadrature Phase Shift Keying (QPSK) for transmitting 8 kbit/sec in 10 kHz user channel bandwidth. We consider Digital Phase Modulation (DPM) as an alternative modulation format for INMARSAT-M. DPM is similar to Continuous Phase Modulation (CPM) except that DPM has a finite memory in the premodular filter with a continuous varying modulation index. It is shown that DPM with 64 states in the VA obtains a lower bit error rate (BER). Results for a 5 kHz system, with the same 8 kbit/sec transmitted bitstream, is also presented.

Grythe, Knut

1990-01-01

411

Spacecraft design project: Low Earth orbit communications satellite  

NASA Technical Reports Server (NTRS)

This is the final product of the spacecraft design project completed to fulfill the academic requirements of the Spacecraft Design and Integration 2 course (AE-4871) taught at the U.S. Naval Postgraduate School. The Spacecraft Design and Integration 2 course is intended to provide students detailed design experience in selection and design of both satellite system and subsystem components, and their location and integration into a final spacecraft configuration. The design team pursued a design to support a Low Earth Orbiting (LEO) communications system (GLOBALSTAR) currently under development by the Loral Cellular Systems Corporation. Each of the 14 team members was assigned both primary and secondary duties in program management or system design. Hardware selection, spacecraft component design, analysis, and integration were accomplished within the constraints imposed by the 11 week academic schedule and the available design facilities.

Moroney, Dave; Lashbrook, Dave; Mckibben, Barry; Gardener, Nigel; Rivers, Thane; Nottingham, Greg; Golden, Bill; Barfield, Bill; Bruening, Joe; Wood, Dave

1991-01-01

412

Speech coding at 4800 bps for mobile satellite communications  

NASA Technical Reports Server (NTRS)

A speech compression project has recently been completed to develop a speech coding algorithm suitable for operation in a mobile satellite environment aimed at providing telephone quality natural speech at 4.8 kbps. The work has resulted in two alternative techniques which achieve reasonably good communications quality at 4.8 kbps while tolerating vehicle noise and rather severe channel impairments. The algorithms are embodied in a compact self-contained prototype consisting of two AT and T 32-bit floating-point DSP32 digital signal processors (DSP). A Motorola 68HC11 microcomputer chip serves as the board controller and interface handler. On a wirewrapped card, the prototype's circuit footprint amounts to only 200 sq cm, and consumes about 9 watts of power.

Gersho, Allen; Chan, Wai-Yip; Davidson, Grant; Chen, Juin-Hwey; Yong, Mei

1988-01-01

413

The geostationary operational environmental satellite /GOES/ imaging communication system  

NASA Technical Reports Server (NTRS)

The SMS/GOES Satellite obtains day and night weather information from synchronous geostationary orbit by means of (1) earth imaging, (2) collection of environmental data from ground based sensors, platforms, and (3) monitoring of the space environment. SMS-1 and SMS-2 have been in orbit for 17 months and 8 months, respectively, and are presently taking full earth disk images in the visible and infrared every 30 minutes. SMS-1 is positioned to cover the eastern portion of the U.S. while SMS-2 is positioned to cover the western portion. This paper provides a general overview of the imaging communication portions of the SMS/GOES, related to the image data encoding and transmission as well as the method of the data time multiplexing and the manner in which the scan line to line synchronization is achieved.

Baker, W. L.; Savides, J.

1975-01-01

414

Experiments applications guide: Advanced Communications Technology Satellite (ACTS)  

NASA Technical Reports Server (NTRS)

This applications guide first surveys the capabilities of the Advanced Communication Technology Satellite (ACTS) system (both the flight and ground segments). This overview is followed by a description of the baseband processor (BBP) and microwave switch matrix (MSM) operating modes. Terminals operating with the baseband processor are referred to as low burst rate (LBR); and those operating with the microwave switch matrix, as high burst rate (HBR). Three very small-aperture terminals (VSATs), LBR-1, LBR-2, and HBR, are described for various ACTS operating modes. Also described is the NASA Lewis link evaluation terminal. A section on ACTS experiment opportunities introduces a wide spectrum of network control, telecommunications, system, and scientific experiments. The performance of the VSATs is discussed in detail. This guide is intended as a catalyst to encourage participation by the telecommunications, business, and science communities in a broad spectrum of experiments.

1988-01-01

415

Assessment of optical communications systems for Data Relay Satellite  

NASA Astrophysics Data System (ADS)

This paper addresses the possibility of using optical technologies to support the high-data-rate communication links of the future European Data Relay Satellite System. Two particular optical technologies are considered based on the use of either CO2 lasers operating at 10.6 microns or semiconductor laser diodes in the 0.8 to 1.3 micron range. The first part of this paper summarizes the performance specifications and design constraints originated by the DRS system proper, the orbital environment and the carrier spacecraft characteristics. After a review of the development status of CO2 and semiconductor laser equipments, the paper is dedicated to a comparative evaluation of the optical terminal for the CO2 and laser diode alternative. Functional block diagrams, expected performances, and system budgets (mass, power) are presented.

Perbos, Jl.; Laurent, B.

1986-10-01

416

Speech coding at 4800 bps for mobile satellite communications  

NASA Astrophysics Data System (ADS)

A speech compression project has recently been completed to develop a speech coding algorithm suitable for operation in a mobile satellite environment aimed at providing telephone quality natural speech at 4.8 kbps. The work has resulted in two alternative techniques which achieve reasonably good communications quality at 4.8 kbps while tolerating vehicle noise and rather severe channel impairments. The algorithms are embodied in a compact self-contained prototype consisting of two AT and T 32-bit floating-point DSP32 digital signal processors (DSP). A Motorola 68HC11 microcomputer chip serves as the board controller and interface handler. On a wirewrapped card, the prototype's circuit footprint amounts to only 200 sq cm, and consumes about 9 watts of power.

Gersho, Allen; Chan, Wai-Yip; Davidson, Grant; Chen, Juin-Hwey; Yong, Mei

1988-05-01

417

Equalization and detection for digital communication over nonlinear bandlimited satellite communication channels. Ph.D. Thesis  

NASA Technical Reports Server (NTRS)

This dissertation evaluates receiver-based methods for mitigating the effects due to nonlinear bandlimited signal distortion present in high data rate satellite channels. The effects of the nonlinear bandlimited distortion is illustrated for digitally modulated signals. A lucid development of the low-pass Volterra discrete time model for a nonlinear communication channel is presented. In addition, finite-state machine models are explicitly developed for a nonlinear bandlimited satellite channel. A nonlinear fixed equalizer based on Volterra series has previously been studied for compensation of noiseless signal distortion due to a nonlinear satellite channel. This dissertation studies adaptive Volterra equalizers on a downlink-limited nonlinear bandlimited satellite channel. We employ as figure of merits performance in the mean-square error and probability of error senses. In addition, a receiver consisting of a fractionally-spaced equalizer (FSE) followed by a Volterra equalizer (FSE-Volterra) is found to give improvement beyond that gained by the Volterra equalizer. Significant probability of error performance improvement is found for multilevel modulation schemes. Also, it is found that probability of error improvement is more significant for modulation schemes, constant amplitude and multilevel, which require higher signal to noise ratios (i.e., higher modulation orders) for reliable operation. The maximum likelihood sequence detection (MLSD) receiver for a nonlinear satellite channel, a bank of matched filters followed by a Viterbi detector, serves as a probability of error lower bound for the Volterra and FSE-Volterra equalizers. However, this receiver has not been evaluated for a specific satellite channel. In this work, an MLSD receiver is evaluated for a specific downlink-limited satellite channel. Because of the bank of matched filters, the MLSD receiver may be high in complexity. Consequently, the probability of error performance of a more practical suboptimal MLSD receiver, requiring only a single receive filter, is evaluated.

Gutierrez, Alberto, Jr.

1995-01-01

418

A spread-spectrum modem using constant envelope BPSK for a mobile satellite communications terminal  

NASA Technical Reports Server (NTRS)

This paper describes a 5-kilobit/s spread spectrum modem with a 1.275 mega-Hz chip rate for mobile satellite communications. We used a Viterbi decoder with a coding gain of 7.8 dB at a BER of 10(exp -5) to decrease the required receiver power. This reduces the cost of communication services. The spread spectrum technique makes the modem immune to terrestrial radio signals and keeps it from causing interference in terrestrial radio systems. A class C power amplifier reduces the modem's power consumption. To avoid nonlinear distortion caused by the amplifier, the envelope of the input signal is kept constant by adding quadrature channel signal to the BPSK signal. To simulate the worst case, we measured the modem's output spectrum using a limiting amplifier instead of the class C amplifier, and found that 99 percent of the spectral power was confined to the specified 2.55 mega-Hz bandwidth.

Iizuka, N.; Yamashita, A.; Takenaka, S.; Morikawa, E.; Ikegami, T.

1990-01-01

419

Fault tolerant onboard packet switch architecture for communication satellites: Shared memory per beam approach  

NASA Technical Reports Server (NTRS)

The NASA Lewis Research Center is developing a multichannel communication signal processing satellite (MCSPS) system which will provide low data rate, direct to user, commercial communications services. The focus of current space segment developments is a flexible, high-throughput, fault tolerant onboard information switching processor. This information switching processor (ISP) is a destination-directed packet switch which performs both space and time switching to route user information among numerous user ground terminals. Through both industry study contracts and in-house investigations, several packet switching architectures were examined. A contention-free approach, the shared memory per beam architecture, was selected for implementation. The shared memory per beam architecture, fault tolerance insertion, implementation, and demonstration plans are described.

Shalkhauser, Mary JO; Quintana, Jorge A.; Soni, Nitin J.

1994-01-01

420

Error control techniques for satellite and space communications  

NASA Technical Reports Server (NTRS)

High rate concatenated coding systems with trellis inner codes and Reed-Solomon (RS) outer codes for application in satellite communication systems are considered. Two types of inner codes are studied: high rate punctured binary convolutional codes which result in overall effective information rates between 1/2 and 1 bit per channel use; and bandwidth efficient signal space trellis codes which can achieve overall effective information rates greater than 1 bit per channel use. Channel capacity calculations with and without side information performed for the concatenated coding system. Concatenated coding schemes are investigated. In Scheme 1, the inner code is decoded with the Viterbi algorithm and the outer RS code performs error-correction only (decoding without side information). In scheme 2, the inner code is decoded with a modified Viterbi algorithm which produces reliability information along with the decoded output. In this algorithm, path metrics are used to estimate the entire information sequence, while branch metrics are used to provide the reliability information on the decoded sequence. This information is used to erase unreliable bits in the decoded output. An errors-and-erasures RS decoder is then used for the outer code. These two schemes are proposed for use on NASA satellite channels. Results indicate that high system reliability can be achieved with little or no bandwidth expansion.

Costello, D. J., Jr.

1986-01-01

421

Mitigating Aviation Communication and Satellite Orbit Operations Surprises from Adverse Space Weather  

NASA Technical Reports Server (NTRS)

Adverse space weather affects operational activities in aviation and satellite systems. For example, large solar flares create highly variable enhanced neutral atmosphere and ionosphere electron density regions. These regions impact aviation communication frequencies as well as precision orbit determination. The natural space environment, with its dynamic space weather variability, is additionally changed by human activity. The increase in orbital debris in low Earth orbit (LEO), combined with lower atmosphere CO2 that rises into the lower thermosphere and causes increased cooling that results in increased debris lifetime, adds to the environmental hazards of navigating in near-Earth space. This is at a time when commercial space endeavors are posed to begin more missions to LEO during the rise of the solar activity cycle toward the next maximum (2012). For satellite and aviation operators, adverse space weather results in greater expenses for orbit management, more communication outages or aviation and ground-based high frequency radio used, and an inability to effectively plan missions or service customers with space-based communication, imagery, and data transferal during time-critical activities. Examples of some revenue-impacting conditions and solutions for mitigating adverse space weather are offered.

Tobiska, W. Kent

2008-01-01

422

Human proximity effects on circular polarized handset antennas in personal satellite communications  

Microsoft Academic Search

Satellite-based systems are the next step in mobile communications. Several low and medium Earth orbit mobile communication satellite systems have been proposed and are currently being deployed. For all these systems, high-performance circularly polarized antennas for the mobile terminals are of importance. Although considerable material is available on circularly polarized antennas, there is an absence of information on how the

Joseph S. Colburn; Yahya Rahmat-Samii

1998-01-01

423

Timing Synchronization in MF-TDMA Systems for Geostationary Satellites[Topics in Radio Communications  

Microsoft Academic Search

The most expensive costs in satellite communication are incurred by the space segment. Therefore, effort should be focused on the efficient use of this resource. One aspect is the optimization of the physical layer, to approach the Shannon limit of channel capacity. In IP-based networks, communication between arbitrary terminals can be established, which must hold for IP-based satellite networks as

Wolfgang Kogler; Harald Schlemmer; Otto Koudelka

2007-01-01

424

Land mobile communications satellite missions (LAMOCOSAMIS) task 2: Functional requirements  

NASA Astrophysics Data System (ADS)

Existing, planned, and foreseeable land mobile communication services in Europe were reviewed. Functional characteristics of available and new services were studied. Assumptions on global architecture were made. Regulatory aspects were investigated. The system should offer two-way telephony with the same quality as for the wire network; continous coverage, except in the low population density area, and including coverage of the coastal area; at least 10 Erlangs/sq km, allowing for a 25 mE per subscriber to serve 400 subscribers/sq km; possibility to call a mobile subscriber without knowing its geographical position, switched-on mobile terminal being permanently located by the system (roaming); automatic switchover of calls without break when a mobile moves from one cell to another (handover); service to users of public transport; possibility to use portable or pocket mobile terminal; and data transmission either by using a modem on the actual analog systems, or directly on the future digital systems, allowing message transmission or facsimile, connection of computer or terminals, with the possibility of integration in the future Integrated Service Digital Network.

1985-12-01

425

Satellite services system analysis study. Volume 4: Service equipment concepts  

NASA Technical Reports Server (NTRS)

Payload deployment equipment is discussed, including payload separation, retention structures, the remote manipulator system, tilt tables, the payload installation and deployment aid, the handling and positioning aid, and spin tables. Close proximity retrieval, and on-orbit servicing equipment is discussed. Backup and contingency equipment is also discussed. Delivery and retrieval of high-energy payloads are considered. Earth return equipment, the aft flight deck, optional, and advanced equipment are also discussed.

1981-01-01

426

Design and Operation of an IR-CAGE For Thermal Vacuum Testing of a Communication Satellite  

Microsoft Academic Search

A specific infrared radiation device was designed and manufactured for infrared simulation on a communication satellite. For the thermal vacuum test of this satellite, radiation fields with different sizes, shapes and radiation intensities were required to deliver additional heating power onto the space- craft panels. Five of the six sides of the cube- shaped satellite had to be equipped with

C. Wuersching

2004-01-01

427

22nd AIAA International Communications Satellite Systems Conference & Exhibit 2004 9 -12 May 2004, Monterey, California  

E-print Network

supporting Internet and data servicesvia satellite. We study the characteristicsof an aeronautical satellite for the satellite link than end-to-end TCP, especiallyin high BER environment. 1 INTRODUCTION The popularity of Internet and mobile communication over the past decadehas prompted for the provision of Internet and other

Baras, John S.

428

On-Board Processing Architectures for Satellite B-ISDN Services.  

National Technical Information Service (NTIS)

Onboard baseband processing architectures for future satellite broadband integrated services digital networks (B-ISDN's) are addressed. To assess the feasibility of implementing satellite B-ISDN services, critical design issues, such as B-ISDN traffic cha...

T. Inukai, D. Shyy, F. Faris

1991-01-01

429

Pervasive E-health services using the DVB-RCS communication technology.  

PubMed

Two-way satellite broadband communication technologies, such as the Digital Video Broadcasting with Return Channel via Satellite (DVB-RCS) technology, endeavour to offer attractive wide-area broadband connectivity for telemedicine applications, taking into consideration the available data rates, Quality of Service (QoS) provision, survivability, flexibility and operational costs, even in remote areas and isolated regions where the terrestrial technologies suffer. This paper describes a wide-area tele-medicine platform, specially suited for homecare services, based on the DVB-RCS and Wi-Fi communication technologies. The presented platform combines medical data acquisition and transfer, patient remote monitoring and teleconference services. Possible operational scenarios concerning this platform and experimental results regarding tele-monitoring, videoconference and medical data transfer are also provided and discussed in the paper. PMID:17685147

Vouyioukas, Demosthenes; Maglogiannis, Ilias; Pasias, Vasilios

2007-08-01

430

NATIONAL ENVIRONMENTAL SATELLITE, DATA, AND INFORMATION SERVICE Library and Information Services Divison  

E-print Network

in China. Pp. -342-344. In: New developments in marine science and technology... , proceedings of the 22ndNATIONAL ENVIRONMENTAL SATELLITE, DATA, AND INFORMATION SERVICE Library and Information Services The management of oceanographic data in China and China's participation in international atmospheric and marine

431

Using satellite communications for a mobile computer network  

NASA Technical Reports Server (NTRS)

The topics discussed include the following: patrol car automation, mobile computer network, network requirements, network design overview, MCN mobile network software, MCN hub operation, mobile satellite software, hub satellite software, the benefits of patrol car automation, the benefits of satellite mobile computing, and national law enforcement satellite.

Wyman, Douglas J.

1993-01-01

432

47 CFR 73.295 - FM subsidiary communications services.  

Code of Federal Regulations, 2010 CFR

...station operations (see § 73.293). Subsidiary communications include, but are not limited to services such as functional music, specialized foreign language programs, radio reading services, utility load management, market and financial data...

2010-10-01

433

47 CFR 73.667 - TV subsidiary communications services.  

Code of Federal Regulations, 2010 CFR

...73.665(a), (b), and (c)). Subsidiary communications include, but are not limited to, services such as functional music, specialized foreign language programs, radio reading services, utility load management, market and financial data...

2010-10-01

434

16 kb\\/s high quality voice encoding for satellite communication networks  

Microsoft Academic Search

A 16 kb\\/s adaptive predictive coding (APC) with maximum likelihood quantization (MLQ), which can cover a range of coding rates from 4.8-16 kb\\/s, for low C\\/N satellite communications systems is described, and its performance is evaluated. The requirements for a 16 kb\\/s voice coding technique in low C\\/N digital satellite communication systems, such as maritime and thin-route communications, are discussed.

Yohtaro Yatsuzuka; Tomohiro Yamazaki; Shigeru Iizuka

1986-01-01

435

A variable data rate satellite user terminal for multimedia communication able to react against weather impairments (DASIA 2002)  

NASA Astrophysics Data System (ADS)

In the frame of Ground Segment products LABEN - a Finmeccanica Company - is developing an advanced Satellite User Terminal for Multimedia Communication able to react against weather impairments. LABEN has been responsible during the Phase B for the design of the Resource Sharing Experiment (RSE) Earth Terminal of the DAVID Program (ASI). The RSE shall demonstrate conceptual and operational feasibility of the variable data rate link with a LEO satellite (DAVID). This abstract wants to provide a brief description of the proposed system and to outline the near future evolution of these Multimedia Earth Terminals linked to new services and applications.

Bux, W.; Ferrari, M.; D'Ambrosio, A.

2002-07-01

436

Laser satellite communication: precise estimation of the satellite position and synchronization and the stabilization of the beam on the receiving satellite  

Microsoft Academic Search

This paper analyses a number of systems and control issues associated with the design of a low orbit communications satellite network. This paper discusses the adaptation of ISDN ATM protocols to the constraints inherent with laser communications. The main proposed change is to replace the link-by-link off band routing by in band arrow routing. The first field is coded using

Lee Young Ju; Tomes Christian

2000-01-01

437

Definition of technology development missions for early space station satellite servicing, volume 1  

NASA Technical Reports Server (NTRS)

The testbed role of an early manned space station in the context of a satellite servicing evolutionary development and flight demonstration technology plan which results in a satellite servicing operational capability is defined. A satellite servicing technology development mission (a set of missions) to be performed on an early manned space station is conceptually defined.

1983-01-01

438

Assessing the technical, economic and policy-centered feasibility of a proposed satellite communication system for the developing world  

E-print Network

Satellite communication systems remain one of the most under utilized development mediums in less industrialized countries. This research proposes to establish a low cost satellite communications system tailored specifically ...

Samuels, Ayanna Terehas

2005-01-01

439

Crew Transfer Options for Servicing of Geostationary Satellites  

NASA Technical Reports Server (NTRS)

In 2011, NASA and DARPA undertook a study to examine capabilities and system architecture options which could be used to provide manned servicing of satellites in Geostationary Earth Orbit (GEO). The study focused on understanding the generic nature of the problem and examining technology requirements, it was not for the purpose of proposing or justifying particular solutions. A portion of this study focused on assessing possible capabilities to efficiently transfer crew between Earth, Low Earth Orbit (LEO), and GEO satellite servicing locations. This report summarizes the crew transfer aspects of manned GEO satellite servicing. Direct placement of crew via capsule vehicles was compared to concepts of operation which divided crew transfer into multiple legs, first between earth and LEO and second between LEO and GEO. In space maneuvering via purely propulsive means was compared to in-space maneuvering which utilized aerobraking maneuvers for return to LEO from GEO. LEO waypoint locations such as equatorial, Kennedy Space Center, and International Space Station inclinations were compared. A discussion of operational concepts is followed by a discussion of appropriate areas for technology development.

Cerro, Jeffrey A.

2012-01-01

440

Helicopter emergency medical service scene communications made easy.  

PubMed

Narrowbanding has caused numerous communication issues. The solution is to use a mutual aid frequency like 123.025. That frequency is 155.3400, and every helicopter emergency medical service operator and emergency medical service agency should name this frequency as "EMS [Emergency Medical Services] Mutual Aid" and preset this frequency for all helicopter emergency medical service scene operations. PMID:25179953

Koval, Michael

2014-01-01

441

A self-verification authentication mechanism for mobile satellite communication systems  

Microsoft Academic Search

In order to provide an opportunity to make personal communication as broad as possible, mobile satellite communication systems have recently drawn much attention. However, any communication system raises two major challenging issues: (1) how to determine whether actors are whom they claim to be; and (2) how to protect data against unauthorized disclosure. Although the secret-key cryptosystem (SKC) and the

Tzung-Her Chen; Wei-Bin Lee; Hsing-Bai Chen

2009-01-01

442

Traffic management of a satellite communication network using stochastic optimization.  

PubMed

The performance of nonhierarchical circuit switched networks at moderate load conditions is improved when alternate routes are made available. Alternate routes, however, introduce instability under heavy and overloaded conditions, and under these load conditions network performance is found to deteriorate. To alleviate this problem, a control mechanism is used where, a fraction of the capacity of each link is reserved for direct routed calls. In this work, a traffic management scheme is developed to enhance the performance of a mesh-connected, circuit-switched satellite communication network. The network load is measured and the network is continually adapted by reconfiguring the map to suit the current traffic conditions. The routing is performed dynamically. The reconfiguration of the network is done by properly allocating the capacity of each link and placing an optimal reservation on each link. The optimization is done by using two neural network-based optimization techniques: simulated annealing and mean field annealing. A comparative study is done between these two techniques. The results from the simulation study show that this method of traffic management performs better than the pure dynamic routing with a fixed configuration. PMID:18263468

Ansari, N; Arulambalam, A; Balasekar, S

1996-01-01

443

Accountable Anonymous Service Usage in Mobile Communication Systems \\Lambda  

E-print Network

Accountable Anonymous Service Usage in Mobile Communication Systems \\Lambda Levente Butty Abstract We introduce a model that allows of anonymous yet accountable service usage in mo­ bile communication systems. This model is based on the introduction of a new business role, called the customer care

Bencsáth, Boldizsár

444

Communication software for physicians' workstations supporting medical imaging services  

Microsoft Academic Search

This paper describes a software communication architecture for medical imaging services. This work aims to provide to the physician the communication facilities to access and track a patient's record or to retrieve medical images from a remote database. The proposed architecture is comprised of a communication protocol and an application programming interface (API). The implemented protocol, namely the Telemedicine Network

George Orphanos; Dimitris Kanellopoulos; Stavros Koubias

1993-01-01

445

The use of satellites in non-geostationary orbits for unloading geostationary communication satellite traffic peaks. Volume 1: Executive summary  

Microsoft Academic Search

The overall objective of this program was to assess the application, economic benefits, and technology and system implications of satellites in non-geostationary (non-GEO) orbits for off-loading peak traffic from GEO communications satellites. The study was organized into four technical tasks which are described in turn. They are: (1) concepts development; (2) system definition; (3) economic comparisons; and (4) technology requirements

K. Price; A. Turner; T. Nguyen; W. Doong; C. Weyandt

1987-01-01