WorldWideScience

Sample records for satellite acts mobile

  1. Mobile satellite communications handbook

    CERN Document Server

    Cochetti, Roger

    2014-01-01

    With a Preface by noted satellite scientist Dr. Ahmad Ghais, the Second Edition reflects the expanded user base for this technology by updating information on historic, current, and planned commercial and military satellite systems and by expanding sections that explain the technology for non-technical professionals.   The book begins with an introduction to satellite communications and goes on to provide an overview of the technologies involved in mobile satellite communications, providing basic introductions to RF Issues, power Issues, link issues and system issues. It describes

  2. Mobile satellite service for Canada

    Science.gov (United States)

    Sward, David

    1988-05-01

    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.

  3. Trends in mobile satellite communication

    Science.gov (United States)

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

    1993-01-01

    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.

  4. Advanced Communications Technology Satellite (ACTS)

    Science.gov (United States)

    Olmstead, Dean A.; Schertler, Ronald J.

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

  5. Advanced Communications Technology Satellite (ACTS)

    Science.gov (United States)

    Gedney, Richard T.; Schertler, Ronald J.

    1989-01-01

    The NASA Advanced Communications Technology Satellite (ACTS) was conceived to help maintain U.S. leadership in the world's communications-satellite market. This experimental satellite is expected to be launched by NASA in 1992 and to furnish the technology necessary for establishing very small aperture terminal digital networks which provide on-demand full-mesh connectivity, and 1.544-MBPS services with only a single hop. Utilizing on-board switching and processing, each individual voice or data circuit can be separately routed to any location in the network. This paper provides an overview of the ACTS and discusses the value of the technology for future communications systems.

  6. Vocoders in mobile satellite communications

    Science.gov (United States)

    Kriedte, W.; Canavesio, F.; dal Degan, N.; Pirani, G.; Rusina, F.; Usai, P.

    Owing to the power constraints that characterize onboard transmission sections, low-bit-rate coders seem suitable for speech communications inside mobile satellite systems. Vocoders that operate at rates below 4.8 kbit/s could therefore be a desirable solution for this application, providing also the redundancy that must be added to cope with the channel error rate. After reviewing the mobile-satellite-systems aspects, the paper outlines the features of two different types of vocoders that are likely to be employed, and the relevant methods of assessing their performances. Finally, some results from computer simulations of the speech transmission systems are reported.

  7. The Omninet mobile satellite system

    Science.gov (United States)

    Salmasi, A.; Curry, W.

    Mobile Satellite System (MSS) design offering relatively low cost voice, data, and position location services to nonmetropolitan areas of North America is proposed. The system provides spectrally efficient multiple access and modulation techniques, and flexible user interconnection to public and private switched networks. Separate UHF and L-band satellites employing two 9.1 m unfurlable antennas each, achieve a 6048 channel capacity and utilize spot beams. Mobile terminals have modular design and employ 5 dBi omnidirectional antennas. Gateway stations (with two 5 m Ku-band antennas) and base stations (with a single 1.8 m Ku-band antenna) transmit terrestrial traffic to the satellite, where traffic is then transponded via an L-band or UHF downlink to mobile users. The Network Management Center uses two 5-m antennas and incorporates the Integrated-Adaptive Mobile Access Protocol to assure demand assignment of satellite capacity. Preliminary implementation of this low-risk system involves a mobile alphanumeric data service employing receive-only terminals at Ku-band projected for 1987, and plans for the launching of L-band receive-only packages as early as 1988.

  8. Mobile satellite plans and status

    Science.gov (United States)

    Anderson, Roy E.

    1987-03-01

    A method for implementing a mobile satellite system (MSS) in the U.S. and Canada, and the services such a system would provide are described. The MSS is to provide mobile communications that are unlimited in range and unaffected by local terrain features. The system's communications can be either voice or digital, and the small, automatic transponders located in vehicles will respond automatically with the data needed to determine the location of the vehicle. Surveys reveal that there are markets for radio telephones and data and dispatch services. Consideration is given to the regulatory status of the MSS.

  9. Design of the American Mobile Satellite System

    Science.gov (United States)

    Kittiver, Charles

    1991-01-01

    This paper presents an overview of the American Mobile Satellite Corporation (AMSC) Mobile Satellite System (MSS). A summary of the mobile satellite (MSAT) design and overall performance is provided. The design and components of both the forward link and return link transponders are described in detail. The design and operation of a unique hybrid matrix amplifier that offers flexible power distribution is outlined. The conceptual design and performance of three types of land mobile antennas are described.

  10. Integration of mobile satellite and cellular systems

    Science.gov (United States)

    Drucker, Elliott H.; Estabrook, Polly; Pinck, Deborah; Ekroot, Laura

    1993-01-01

    By integrating the ground based infrastructure component of a mobile satellite system with the infrastructure systems of terrestrial 800 MHz cellular service providers, a seamless network of universal coverage can be established. Users equipped for both cellular and satellite service can take advantage of a number of features made possible by such integration, including seamless handoff and universal roaming. To provide maximum benefit at lowest posible cost, the means by which these systems are integrated must be carefully considered. Mobile satellite hub stations must be configured to efficiently interface with cellular Mobile Telephone Switching Offices (MTSO's), and cost effective mobile units that provide both cellular and satellite capability must be developed.

  11. Satellite mobile data service for Canada

    Science.gov (United States)

    Egan, Glenn R.; Sward, David J.

    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.

  12. Secure voice for mobile satellite applications

    Science.gov (United States)

    Vaisnys, Arvydas; Berner, Jeff

    The initial system studies are described which were performed at JPL on secure voice for mobile satellite applications. Some options are examined for adapting existing Secure Telephone Unit III (STU-III) secure telephone equipment for use over a digital mobile satellite link, as well as for the evolution of a dedicated secure voice mobile earth terminal (MET). The work has included some lab and field testing of prototype equipment. The work is part of an ongoing study at JPL for the National Communications System (NCS) on the use of mobile satellites for emergency communications. The purpose of the overall task is to identify and enable the technologies which will allow the NCS to use mobile satellite services for its National Security Emergency Preparedness (NSEP) communications needs. Various other government agencies will also contribute to a mobile satellite user base, and for some of these, secure communications will be an essential feature.

  13. Secure voice for mobile satellite applications

    Science.gov (United States)

    Vaisnys, Arvydas; Berner, Jeff

    1990-01-01

    The initial system studies are described which were performed at JPL on secure voice for mobile satellite applications. Some options are examined for adapting existing Secure Telephone Unit III (STU-III) secure telephone equipment for use over a digital mobile satellite link, as well as for the evolution of a dedicated secure voice mobile earth terminal (MET). The work has included some lab and field testing of prototype equipment. The work is part of an ongoing study at JPL for the National Communications System (NCS) on the use of mobile satellites for emergency communications. The purpose of the overall task is to identify and enable the technologies which will allow the NCS to use mobile satellite services for its National Security Emergency Preparedness (NSEP) communications needs. Various other government agencies will also contribute to a mobile satellite user base, and for some of these, secure communications will be an essential feature.

  14. Mobile satellite service in the United States

    Science.gov (United States)

    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

    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.

  15. Proceedings of the Mobile Satellite Conference

    Science.gov (United States)

    Rafferty, William

    1988-01-01

    A satellite-based mobile communications system provides voice and data communications to mobile users over a vast geographic area. The technical and service characteristics of mobile satellite systems (MSSs) are presented and form an in-depth view of the current MSS status at the system and subsystem levels. Major emphasis is placed on developments, current and future, in the following critical MSS technology areas: vehicle antennas, networking, modulation and coding, speech compression, channel characterization, space segment technology and MSS experiments. Also, the mobile satellite communications needs of government agencies are addressed, as is the MSS potential to fulfill them.

  16. The use of mobile satellite communication terminals

    Science.gov (United States)

    Law, P. A.

    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.

  17. A new digital land mobile satellite system

    Science.gov (United States)

    Schneider, Philip

    A description is given of the different digital services planned to be carried over existing and planned mobile satellite systems. These systems are then compared with analog services in terms of bandwidth and power efficiency. This comparison provides the rationale for the establishment of a digital land mobile satellite service (DLMSS) to use frequencies that are currently available but not yet assigned to a domestic mobile satellite system in the United States. The focus here is on the expected advantages of digital transmission techniques in accommodating additional mobile satellite systems in this portion of the spectrum, and how such techniques can fully satisfy voice, data and facsimile mobile communications requirements in a cost effective manner. A description is given of the system architecture of the DMLSS service proposed by the Geostar Messaging Corporation (GMC) and the market potential of DLMSS.

  18. An Active K-Band Receive Slot Array for Mobile Satellite Communications

    Science.gov (United States)

    Tulintseff, A. N.; Lee, K. A.; Sukamto, L. M.; Chew, W.

    1994-01-01

    An active receive slot array has been developed for operation in the downlink frequency band, 19.914-20.064 GHz, of NASA's Advanced Communication Technology Satellite (ACTS) for the ACTS Mobile Terminal (AMT) project.

  19. Integration of Mobil Satellite and Cellular Systems

    Science.gov (United States)

    Drucker, E. H.; Estabrook, P.; Pinck, D.; Ekroot, L.

    1993-01-01

    By integrating the ground based infrastructure component of a mobile satellite system with the infrastructure systems of terrestrial 800 MHz cellular service providers, a seamless network of universal coverage can be established.

  20. An access alternative for mobile satellite networks

    Science.gov (United States)

    Wu, W. W.

    1988-05-01

    Conceptually, this paper discusses strategies of digital satellite communication networks for a very large number of low density traffic stations. These stations can be either aeronautical, land mobile, or maritime. The techniques can be applied to international, domestic, regional, and special purpose satellite networks. The applications can be commercial, scientific, military, emergency, navigational or educational. The key strategy is the use of a non-orthogonal access method, which tolerates overlapping signals. With n being either time or frequency partitions, and with a single overlapping signal allowed, a low cost mobile satellite system can be designed with n squared (n squared + n + 1) number of terminals.

  1. Spacecraft (Mobile Satellite) configuration design study

    Science.gov (United States)

    1985-01-01

    The relative costs to procure and operate a two-satellite mobile satellite system designed to operate either in the UHF band of the L Band, and with several antenna diameter options in each frequency band was investigated. As configured, the size of the spacecraft is limited to the current RCA Series 4000 Geosynchronous Communications Spacecraft bus, which spans the range from 4000 to 5800 pounds in the transfer orbit. The Series 4000 bus forms the basis around which the Mobile Satellite transponder and associated antennas were appended. Although the resultant configuration has little outward resemblance to the present Series 4000 microwave communications spacecraft, the structure, attitude control, thermal, power, and command and control subsystems of the Series 4000 spacecraft are all adapted to support the Mobile Satellite mission.

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

    Science.gov (United States)

    Hoder, Douglas; Bergamo, Marcos

    1996-01-01

    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.

  3. Mobile satellite communications - Vehicle antenna technology update

    Science.gov (United States)

    Bell, D.; Naderi, F. M.

    1986-01-01

    This paper discusses options for vehicle antennas to be used in mobile satellite communications systems. Two types of antennas are identified. A non-steerable, azimuthally omnidirectional antenna with a modest gain of 3 to 5 dBi is suggested when a low cost is desired. Alternatively, mechanically or electronically steerable antennas with a higher gain of 10 to 12 dBi are suggested to alleviate power and spectrum scarcity associated with mobile satellite communications. For steerable antennas, both open-loop and closed-loop pointing schemes are discussed. Monopulse and sequential lobing are proposed for the mechanically steered and electronically steered antennas, respectively. This paper suggests a hybrid open-loop/closed-loop pointing technique as the best performer in the mobile satellite environment.

  4. Mobile satellite communications for consumers

    Science.gov (United States)

    Noreen, Gary K.

    1991-11-01

    The RadioSat system based on MSAT satellites and scheduled for launch in 1994 is described. The RadioSat system will provide integrated communications and navigation services to consumers, including nationwide digital audio broadcasts, data broadcasts, precision navigation, and two-way voice and data communications. Particular attention is given to the MSAT satellite system capabilities and economics. It is concluded that the RadioSat system will be capable of providing a low-cost, highly flexible two-way communications for consumers that can be adapted to various applications.

  5. Mobile satellites - The possibility of universal service

    Science.gov (United States)

    Kiesling, John D.

    The characteristics of a mobile satellite service (MSS), which is a communications system capable of voice and data transmission and position location services using analogue and digital techniques, are described. Consideration is given to the use of the MSS for radio telephone and private mobile radio services, the costs of these services, and market demand for the MSS. The designs for the space segment and gateway network for the MSS are proposed. The requirements for the mobile radios and antennas of the MSS are discussed.

  6. 75 FR 49871 - Fixed and Mobile Services in the Mobile Satellite Service

    Science.gov (United States)

    2010-08-16

    ... COMMISSION 47 CFR Parts 1, 2 and 25 Fixed and Mobile Services in the Mobile Satellite Service AGENCY: Federal... Commission proposes to add co-primary Fixed and Mobile allocations to the existing Mobile-Satellite... mobile satellite capability to serve important needs like disaster recovery and rural access....

  7. Vehicle antenna development for mobile satellite applications

    Science.gov (United States)

    Woo, K.

    1988-01-01

    The paper summarizes results of a vehicle antenna program at JPL in support of a developing U.S. mobile satellite services (MSS) designed to provide telephone and data services for the continental United States. Two classes of circularly polarized vehicle antennas have been considered for the MSS: medium-gain, satellite-tracking antennas with 10-12-dBic gain; and low-gain, azimuthally omnidirectional antennas with 3-5-dBic gain. The design and performance of these antennas are described, and the two antennas are shown to have peculiar advantages and disadvantages.

  8. Land mobile satellite services in Europe

    Science.gov (United States)

    Bartholome, P.; Rogard, R.; Berretta, G.

    1988-10-01

    The potential role of satellite communication as a complement to the pan-European cellular telephone network being developed to replace the current national or regional networks in the mid 1990s is discussed. The design concept and capabilities of the all-digital cellular network are reviewed; the requirements not covered by the network are listed; market-survey results indicating business interest in these additional services are summarized; and particular attention is given to the ESA demonstration system PRODAT. PRODAT uses the Marecs satellite to provide low-rate two-way data transmission for mobile terminals; the CDMA technique is used for the return links from mobile unit to hub station.

  9. LTE Adaptation for Mobile Broadband Satellite Networks

    Directory of Open Access Journals (Sweden)

    Bastia Francesco

    2009-01-01

    Full Text Available One of the key factors for the successful deployment of mobile satellite systems in 4G networks is the maximization of the technology commonalities with the terrestrial systems. An effective way of achieving this objective consists in considering the terrestrial radio interface as the baseline for the satellite radio interface. Since the 3GPP Long Term Evolution (LTE standard will be one of the main players in the 4G scenario, along with other emerging technologies, such as mobile WiMAX; this paper analyzes the possible applicability of the 3GPP LTE interface to satellite transmission, presenting several enabling techniques for this adaptation. In particular, we propose the introduction of an inter-TTI interleaving technique that exploits the existing H-ARQ facilities provided by the LTE physical layer, the use of PAPR reduction techniques to increase the resilience of the OFDM waveform to non linear distortion, and the design of the sequences for Random Access, taking into account the requirements deriving from the large round trip times. The outcomes of this analysis show that, with the required proposed enablers, it is possible to reuse the existing terrestrial air interface to transmit over the satellite link.

  10. Inmarsat and personal mobile satellite services

    Science.gov (United States)

    McDougal, Patrick; Barendse, Victor

    Personal communications - mobile satellite services (PC-MSS) hold much promise as a profitable business opportunity for a number of interested operators and manufacturers. What will be their impact on the overall mobile communications landscape, and what role will they play in the drive towards the universal personal communicator? It is the thesis of this paper that PC-MSS can provide one of the critical enabling technologies to allow a more rapid, global assimilation of personal mobile communications. Terrestrial mobile communications are local by definition, both in terms of service reach and regulatory oversight. It is estimated that cellular, and other forms of terrestrial mobile communications, will cover over 50% of the world's population, but only 15% of the land mass area by the year 2000. PC-MSS will allow 'cellular extension' to interested users in the uncovered parts of the world. The market opportunity is established and technical solutions are available. However 'user cooperation' will be required and cross mapping of market needs to the technology solutions is the key to financially viable solutions. The potential political and regulatory hurdles are daunting. Inmarsat, as the existing global MSS partnership, is already introducing PC-MSS products and services in the 1990s. The widespread use of briefcase satphones (Inm-M), laptop-sized data terminals (Inm-C), and pocket satpagers (Inm-paging) will break new ground in reshaping the international regulatory context of mobile communications, and in initiating the optimal public switched network integration necessary for global interconnect. It is suggested that this evolutionary approach, by means of international consensus-building within a global partnership of operators, is an effective and proven method to ensure both a sufficient financial return for investors, and fair and equitable access of these services for all countries and users.

  11. SAW based systems for mobile communications satellites

    Science.gov (United States)

    Peach, R. C.; Miller, N.; Lee, M.

    1993-01-01

    Modern mobile communications satellites, such as INMARSAT 3, EMS, and ARTEMIS, use advanced onboard processing to make efficient use of the available L-band spectrum. In all of these cases, high performance surface acoustic wave (SAW) devices are used. SAW filters can provide high selectivity (100-200 kHz transition widths), combined with flat amplitude and linear phase characteristics; their simple construction and radiation hardness also makes them especially suitable for space applications. An overview of the architectures used in the above systems, describing the technologies employed, and the use of bandwidth switchable SAW filtering (BSSF) is given. The tradeoffs to be considered when specifying a SAW based system are analyzed, using both theoretical and experimental data. Empirical rules for estimating SAW filter performance are given. Achievable performance is illustrated using data from the INMARSAT 3 engineering model (EM) processors.

  12. Improving TCP Performance over Mobile Satellite Channels: The ACKPrime Approach

    Science.gov (United States)

    Scott, Keith; Czetty, Stephen

    1998-01-01

    Various issues associated with "Improving TCP Performance over Mobile Satellite Channels: The ACKPrime Approach" are presented in viewgraph form. Specific topics include: 1) TCP over mobile satellite links; 2) ways of breaking the control loop at the groundstation; 3) ACK implementation; and 4) ACK performance.

  13. A generalized transmultiplexer and its application to mobile satellite communications

    Science.gov (United States)

    Ichiyoshi, Osamu

    A generalization of digital transmultiplexer technology is presented. The proposed method can realize transmultiplexer (TMUX) and transdemultiplexer (TDUX) filter banks whose element filters have bandwidths greater than the channel spacing frequency. This feature is useful in many communications applications. As an example, a satellite switched (SS) Frequency Division Multiple Access (FDMA) system is proposed for spot beam satellite communications, particularly for mobile satellite communications.

  14. Propagation considerations in the American Mobile Satellite system design

    Science.gov (United States)

    Kittiver, Charles; Sigler, Charles E., Jr.

    1993-01-01

    An overview of the American Mobile Satellite Corporation (AMSC) mobile satellite services (MSS) system with special emphasis given to the propagation issues that were considered in the design is presented. The aspects of the voice codec design that effect system performance in a shadowed environment are discussed. The strategies for overcoming Ku-Band rain fades in the uplink and downlink paths of the gateway station are presented. A land mobile propagation study that has both measurement and simulation activities is described.

  15. Technical comparison of several global mobile satellite communications systems

    Science.gov (United States)

    Comparetto, Gary M.

    The era of satellite-based mobile satellite communications (MSC) systems started with the first MARISAT satellite which was launched into a geostationary orbit over the Pacific Ocean in 1976 to provide communications between ships and shore stations. The combination of high cost and unacceptably large equipment has kept the space-based MSC systems from appealing to the wider market of personal mobile communications. The progress made over the last ten years, however, in digital voice processing, satellite technology, and component miniaturization has resulted in the viability of satellite-based mobile satellite communications systems to meet the growing market in personal mobile communications using handsets similar to those currently in use with land-based cellular systems. Three of the more mature LEO/MEO satellite systems are addressed in this paper including GLOBALSTAR, Iridium, and Odyssey. The system architectures of each system are presented along with a description of the satellite and user handset designs and the multiaccess techniques employed. It will be shown that, although a number of similarities exist among the system addressed, each system is unique in a variety of significant design areas. It is concluded that the technical feasibility of satellite-based mobile satellite communications systems seems to be secure. It will be challenging, however, for the vendors to actually develop and deploy these systems in a cost effective, timely, and reliable way that meets a continually evolving set of requirements based upon a rapidly changing technology base.

  16. Mobile communications by satellite in Europe - Overview of ESA activities

    Science.gov (United States)

    Rogard, R.; Jongejans, A.; Bartholome, P.

    ESA is conducting studies aimed at the definition of a Land Mobile Satellite System for digital communications within the Western European region, in view of recent market studies indicating the existence of substantial demand for the provision of mobile communications services by satellite. Attention is presently given to the 'Prodat' low-rate system and its ARQ-coding scheme, Prodat's CDMA return link (noting interference protection and spectrum use efficiency criteria) and the aims of Prodat performance trials.

  17. NASA's mobile satellite communications program; ground and space segment technologies

    Science.gov (United States)

    Naderi, F.; Weber, W. J.; Knouse, G. H.

    1984-10-01

    This paper describes the Mobile Satellite Communications Program of the United States National Aeronautics and Space Administration (NASA). The program's objectives are to facilitate the deployment of the first generation commercial mobile satellite by the private sector, and to technologically enable future generations by developing advanced and high risk ground and space segment technologies. These technologies are aimed at mitigating severe shortages of spectrum, orbital slot, and spacecraft EIRP which are expected to plague the high capacity mobile satellite systems of the future. After a brief introduction of the concept of mobile satellite systems and their expected evolution, this paper outlines the critical ground and space segment technologies. Next, the Mobile Satellite Experiment (MSAT-X) is described. MSAT-X is the framework through which NASA will develop advanced ground segment technologies. An approach is outlined for the development of conformal vehicle antennas, spectrum and power-efficient speech codecs, and modulation techniques for use in the non-linear faded channels and efficient multiple access schemes. Finally, the paper concludes with a description of the current and planned NASA activities aimed at developing complex large multibeam spacecraft antennas needed for future generation mobile satellite systems.

  18. NASA's mobile satellite communications program; ground and space segment technologies

    Science.gov (United States)

    Naderi, F.; Weber, W. J.; Knouse, G. H.

    1984-01-01

    This paper describes the Mobile Satellite Communications Program of the United States National Aeronautics and Space Administration (NASA). The program's objectives are to facilitate the deployment of the first generation commercial mobile satellite by the private sector, and to technologically enable future generations by developing advanced and high risk ground and space segment technologies. These technologies are aimed at mitigating severe shortages of spectrum, orbital slot, and spacecraft EIRP which are expected to plague the high capacity mobile satellite systems of the future. After a brief introduction of the concept of mobile satellite systems and their expected evolution, this paper outlines the critical ground and space segment technologies. Next, the Mobile Satellite Experiment (MSAT-X) is described. MSAT-X is the framework through which NASA will develop advanced ground segment technologies. An approach is outlined for the development of conformal vehicle antennas, spectrum and power-efficient speech codecs, and modulation techniques for use in the non-linear faded channels and efficient multiple access schemes. Finally, the paper concludes with a description of the current and planned NASA activities aimed at developing complex large multibeam spacecraft antennas needed for future generation mobile satellite systems.

  19. 75 FR 63534 - Seventh Meeting-Special Committee 222: Inmarsat Aeronautical Mobile Satellite (Route) Services

    Science.gov (United States)

    2010-10-15

    ...: Inmarsat Aeronautical Mobile Satellite (Route) Services. The agenda will include: Agenda Opening Plenary... Satellite (Route) Services AGENCY: Federal Aviation Administration (FAA), DOT. ACTION: Notice of RTCA Special Committee 222: Inmarsat Aeronautical Mobile Satellite (Route) Services meeting. SUMMARY: The...

  20. 47 CFR 80.333 - Stations in the maritime mobile-satellite service.

    Science.gov (United States)

    2010-10-01

    ... 47 Telecommunication 5 2010-10-01 2010-10-01 false Stations in the maritime mobile-satellite..., Alarm, Urgency and Safety Procedures § 80.333 Stations in the maritime mobile-satellite service. The...-satellite service....

  1. Spread spectrum mobile communication experiment using ETS-V satellite

    Science.gov (United States)

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

    1990-01-01

    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.

  2. Land vehicle antennas for satellite mobile communications

    Science.gov (United States)

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

    1985-01-01

    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.

  3. 47 CFR 25.143 - Licensing provisions for the 1.6/2.4 GHz mobile-satellite service and 2 GHz mobile-satellite...

    Science.gov (United States)

    2010-10-01

    ...-satellite service and 2 GHz mobile-satellite service. 25.143 Section 25.143 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) COMMON CARRIER SERVICES SATELLITE COMMUNICATIONS Applications and Licenses Space Stations § 25.143 Licensing provisions for the 1.6/2.4 GHz mobile-satellite service and 2...

  4. Satellite augmentation of cellular type mobile radio telephone systems

    Science.gov (United States)

    Anderson, Roy E.

    NASA's ATS-6 satellite relayed voice bandwidth communications between five trucks and the trucking company dispatchers as the trucks traveled throughout the north-eastern quarter of the contiguous United States. The experiment, conducted over a seven month period, demonstrated that propagation characteristics are much different for the satellite-mobile links than for terrestrial-mobile links. A properly designed satellite system can provide high quality, reliable voice and data communications except where the vehicle-satellite path is shadowed by a structure or terrain feature. Mobile equipment in the experiment was adapted from commercial mobile radios. The vehicle antennas were 75 cm tall, 2 cm diam. Another experiment proved the feasibility of vehicle position surveillance using active two-way tone-code ranging through ATS-6 to provide one line of position and passive one-way ranging by measuring the time-of-arrival of a signal from an independent satellite. A position fix was printed out at an earth station 1 sec after it sent the interrogation signal to the distant vehicle, a towboat on the Mississippi River. The line of position from ATS-6 was accurate to 0.1 nautical mile using a voice bandwidth ranging signal. The line of position from the NOAA GOES satellite was accurate to 2 miles, using 100 Hz signal bandwidth. If the signal from the independent satellite had the same bandwidth and signal-to-noise ratio as ATS-6, the fixes would have been accurate to about 0.1 nautical mile. A concept study concluded that satellites might be a cost effective augmentation of terrestrial cellular type mobile radio telephone systems. The satellites would serve thinly populated areas where terrestrial systems are not cost effective. In the United States, the satellites would serve about 90% of the land area where 20% of the population resides. A multibeam satellite with many channels in each beam would be compatible with the urban terrestrial systems and together they would

  5. Land mobile satellite propagation measurements in Japan using ETS-V satellite

    Science.gov (United States)

    Obara, Noriaki; Tanaka, Kenji; Yamamoto, Shin-Ichi; Wakana, Hiromitsu

    1993-01-01

    Propagation characteristics of land mobile satellite communications channels have been investigated actively in recent years. Information of propagation characteristics associated with multipath fading and shadowing is required to design commercial land mobile satellite communications systems, including protocol and error correction method. CRL (Communications Research Laboratory) has carried out propagation measurements using the Engineering Test Satellite-V (ETS-V) at L band (1.5 GHz) through main roads in Japan by a medium gain antenna with an autotracking capability. This paper presents the propagation statistics obtained in this campaign.

  6. PERFORMANCES OF ADAPTIVE MODULATION AND CODING IN SATELLITE MOBILE CHANNEL

    Institute of Scientific and Technical Information of China (English)

    Yu Fangyuan; Yang Mingchuan; Guo Qing

    2011-01-01

    Given that satellite mobile channel is a time-varying channel,Adaptive Modulation and Coding (AMC) was proposed to provide robust and spectrally efficient transmission over satellite mobile channel.Three different kinds of channel environment were considered in this paper:the urban area,the rural area,and the open space.Four combinations of modulation and coding were designed to meet reliable communication on time-varying channel,and spectral efficiency and system throughput of these three kinds of channel environment were simulated.Based on the simulation results,this paper analysed the results and compared the performances of AMC with non-AMC system in these three kinds of channel environment.At last,we come to the conclusions:a system with AMC can achieve higher spectral efficiency and better system throughput; and the spectral efficiency and system throughput of AMC system will be higher on better satellite mobile channel.

  7. First satellite mobile communication trials using BLQS-CDMA

    Science.gov (United States)

    Luzdemateo, Maria; Johns, Simon; Dothey, Michel; Vanhimbeeck, Carl; Deman, Ivan; Wery, Bruno

    1993-01-01

    In this paper, technical results obtained in the first MSBN Land mobile technical trial are reported. MSBN (Mobile Satellite Business Network) is a new program undertaken by the European Space Agency (ESA) to promote mobile satellite communication in Europe, in particular voice capability. The first phase of the MSBN system implementation plan is an experimental phase. Its purpose is to evaluate through field experiments the performance of the MSBN system prior to finalization of its specifications. Particularly, the objective is to verify in the field and possibly improve the performance of the novel satellite access technique BLQS-CDMA (Band Limited Quasi-Synchronous-Code Division Multiple Access), which is proposed as baseline for the MSBN.

  8. 47 CFR 80.1185 - Supplemental eligibility for mobile-satellite stations.

    Science.gov (United States)

    2010-10-01

    ... 47 Telecommunication 5 2010-10-01 2010-10-01 false Supplemental eligibility for mobile-satellite...-Satellite Stations § 80.1185 Supplemental eligibility for mobile-satellite stations. Stations in the maritime mobile-satellite service must meet the eligibility requirements contained in this section. (a)...

  9. Satellite-aided mobile radio concepts study: Concept definition of a satellite-aided mobile and personal radio communication system

    Science.gov (United States)

    Anderson, R. E.

    1979-01-01

    The satellite system requires the use of a large satellite antenna and spacecraft array power of about 12 kW or more depending on the operating frequency. Technology developments needed include large offset reflector multibeam antennas, satellite electrical power sybsystems providing greater than 12 kW of power, signal switching hardware, and linearized efficient solid state amplifiers for the satellite-aided mobile band. Presently there is no frequency assignment for this service, and it is recommended that an allocation be pursued. The satellite system appears to be within reasonable extrapolation of the state of the art. It is further recommended that the satellite-aided system spacecraft definition studies and supporting technology development be initiated.

  10. Narrowband and wideband characterisation of satellite mobile/PCN channel

    Science.gov (United States)

    Butt, G.; Parks, M. A. N.; Evans, B. G.

    1995-01-01

    This paper presents models characterizing satellite mobile channel. Statistical narrowband models based on the CSER high elevation angle channel measurement campaign are reported. Such models are understood to be useful for communication system simulations. It has been shown from the modelling results that for the mobile satellite links at high elevation angles line-of-sight (LOS) signal is available most of the time, even under the heavy shadowing conditions. Wideband measurement campaign which CSER is about to undertake, and subsequently the modelling approach to be adopted is also discussed. It is noted that a wideband channel model is expected to provide a useful tool in investigating CDMA applications.

  11. A Minimum Cost Handover Algorithm for Mobile Satellite Networks

    Institute of Scientific and Technical Information of China (English)

    Zhang Tao; Zhang Jun

    2008-01-01

    For mobile satellite networks,an appropriate handover scheme should be devised to shorten handover delay with optimized application of network resources.By introducing the handover cost model of service,this article proposes a rerouting triggering scheme for path optimization after handover and a new minimum cost handover algorithm for mobile satellite networks.This algorithm ensures the quality of service (QoS) parameters,such as delay,during the handover and minimizes the handover costs.Simulation indicates that this algorithm is superior to other current algorithms in guaranteeing the QoS and decreasing handover costs.

  12. Mobile satellite communications technology - A summary of NASA activities

    Science.gov (United States)

    Dutzi, E. J.; Knouse, G. H.

    1986-01-01

    Studies in recent years indicate that future high-capacity mobile satellite systems are viable only if certain high-risk enabling technologies are developed. Accordingly, NASA has structured an advanced technology development program aimed at efficient utilization of orbit, spectrum, and power. Over the last two years, studies have concentrated on developing concepts and identifying cost drivers and other issues associated with the major technical areas of emphasis: vehicle antennas, speech compression, bandwidth-efficient digital modems, network architecture, mobile satellite channel characterization, and selected space segment technology. The program is now entering the next phase - breadboarding, development, and field experimentation.

  13. Analysis of Maritime Mobile Satellite Communication Systems

    Science.gov (United States)

    1988-12-01

    Communications and Surveil- lance, IEE, Conference publication n.95, 13-15 Mar. 1973. 2. Y. Karasawa and T. Shiokawa , Characteristics of L-Band Multipath Fading... Shiokawa . Analysis of M-ultipath Fading due to Sea Suface Scattering in Maritime Satellite Communication, Technical Group on Antennas and Propagation. IECE

  14. 75 FR 46885 - Satellite Television Extension and Localism Act of 2010 and Satellite Home Viewer Extension and...

    Science.gov (United States)

    2010-08-04

    ... COMMISSION 47 CFR Part 73 Satellite Television Extension and Localism Act of 2010 and Satellite Home Viewer.... SUMMARY: In this document the Commission proposes to implement provisions of the ``Satellite Television... measurements pursuant to the Satellite Home Viewer Extension and Reauthorization Act of 2004 (SHVERA), but...

  15. 75 FR 80425 - Satellite Television Extension and Localism Act of 2010 and Satellite Home Viewer Extension and...

    Science.gov (United States)

    2010-12-22

    ... COMMISSION 47 CFR Part 73 Satellite Television Extension and Localism Act of 2010 and Satellite Home Viewer... requirements and provisions of the Satellite Television Extension and Localism Act of 2010 (STELA). This model... satellite television service is eligible for delivery of distant network signals from that service....

  16. System architecture for the Canadian interim mobile satellite system

    Science.gov (United States)

    Shariatmadar, M.; Gordon, K.; Skerry, B.; Eldamhougy, H.; Bossler, D.

    1988-05-01

    The system architecture for the Canadian Interim Mobile Satellite Service (IMSS) which is planned for commencement of commercial service in late 1989 is reviewed. The results of an associated field trial program which was carried out to determine the limits of coverage and the preliminary performance characteristics of the system are discussed.

  17. Fade durations in satellite-path mobile radio propagation

    Science.gov (United States)

    Schmier, Robert G.; Bostian, Charles W.

    1986-01-01

    Fades on satellite to land mobile radio links are caused by several factors, the most important of which are multipath propagation and vegetative shadowing. Designers of vehicular satellite communications systems require information about the statistics of fade durations in order to overcome or compensate for the fades. Except for a few limiting cases, only the mean fade duration can be determined analytically, and all other statistics must be obtained experimentally or via simulation. This report describes and presents results from a computer program developed at Virginia Tech to simulate satellite path propagation of a mobile station in a rural area. It generates rapidly-fading and slowly-fading signals by separate processes that yield correct cumulative signal distributions and then combines these to simulate the overall signal. This is then analyzed to yield the statistics of fade duration.

  18. Navigation using local position determination from a mobile satellite terminal

    Science.gov (United States)

    Kee, Steven M.; Marquart, Robert C.

    The authors describe the implementation and performance evaluation of a location-determination system which uses a mobile satellite transmitter for one-way communications of position data for vehicle tracking. Field results have demonstrated that a mobile satellite terminal can provide reliable messaging and position reporting for many over-the-road applications. With installation techniques suitable for nontechnical personnel using a minimum of test equipment, the mobile terminal can provide proximity reporting adequate for most fleet dispatch requirements. Position data with one-way or two-way communications can improve the logistics and management of service fleets by eliminating deadhead mileage, maximizing route efficiencies, and heading off problems with up-to-date status information of transported loads.

  19. Use of CDMA access technology in mobile satellite systems

    Science.gov (United States)

    Ramasastry, Jay; Wiedeman, Bob

    1995-01-01

    Use of Code Division Multiple Access (CDMA) technology in terrestrial wireless systems is fairly well understood. Similarly, design and operation of Power Control in a CDMA-based system in a terrestrial environment is also well established. Terrestrial multipath characteristics, and optimum design of the CDMA receiver to deal with multipath and fading conditions are reliably established. But the satellite environment is different. When the CDMA technology is adopted to the satellite environment, other design features need to be incorporated (for example; interleaving, open-loop and closed-loop power control design, diversity characteristics) to achieve comparable level of system performance. In fact, the GLOBALSTAR LEO/MSS system has incorporated all these features. Contrary to some published reports, CDMA retains the advantages in the satellite environment that are similar to those achieved in the terrestrial environment. This document gives a description of the CDMA waveform and other design features adopted for mobile satellite applications.

  20. Advanced Communication Technology Satellite (ACTS) multibeam antenna technology verification experiments

    Science.gov (United States)

    Acosta, Roberto J.; Larko, Jeffrey M.; Lagin, Alan R.

    1992-01-01

    The Advanced Communication Technology Satellite (ACTS) is a key to reaching NASA's goal of developing high-risk, advanced communications technology using multiple frequency bands to support the nation's future communication needs. Using the multiple, dynamic hopping spot beams, and advanced on board switching and processing systems, ACTS will open a new era in communications satellite technology. One of the key technologies to be validated as part of the ACTS program is the multibeam antenna with rapidly reconfigurable hopping and fixed spot beam to serve users equipped with small-aperature terminals within the coverage areas. The proposed antenna technology experiments are designed to evaluate in-orbit ACTS multibeam antenna performance (radiation pattern, gain, cross pol levels, etc.).

  1. Cockpit weather graphics using mobile satellite communications

    Science.gov (United States)

    Seth, Shashi

    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.

  2. Personal communications via ACTS satellite HBR transponders

    Science.gov (United States)

    Fang, Russell J. F.

    1991-09-01

    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 resources of the transponder are efficiently shared by users in a simple demand-assigned manner via code-division multiple access (CDMA). Voice, data, and facsimile are statistically multiplexed at each terminal. In order to minimize terminal costs, frequency-precorrected, and level-preadjusted continuous-wave tones are sent from the central network control station in each beam so that the terminals in each down-link beam can use these pilots as references for antenna acquisition and tracking, as reliable frequency sources, and as indicators of signal fade for up-link power control (ULPC). The potential CDMA 'near-far' problem due to up-link fades is mitigated by using ULPC. Quasi-burst mode transmission is employed to minimize the potential clock and pseudorandom number code synchronization.

  3. Why is CDMA the solution for mobile satellite communication

    Science.gov (United States)

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

    1989-01-01

    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.

  4. Evaluation of CDMA system capacity for mobile satellite system applications

    Science.gov (United States)

    Smith, Partrick O.; Geraniotis, Evaggelos A.

    1988-01-01

    A specific Direct-Sequence/Pseudo-Noise (DS/PN) Code-Division Multiple-Access (CDMA) mobile satellite system (MSAT) architecture is discussed. The performance of this system is evaluated in terms of the maximum number of active MSAT subscribers that can be supported at a given uncoded bit-error probability. The evaluation decouples the analysis of the multiple-access capability (i.e., the number of instantaneous user signals) from the analysis of the multiple-access mutliplier effect allowed by the use of CDMA with burst-modem operation. We combine the results of these two analyses and present numerical results for scenarios of interest to the mobile satellite system community.

  5. Analogue and digital linear modulation techniques for mobile satellite

    Science.gov (United States)

    Whitmarsh, W. J.; Bateman, A.; Mcgeehan, J. P.

    1990-01-01

    The choice of modulation format for a mobile satellite service is complex. The subjective performance is summarized of candidate schemes and voice coder technologies. It is shown that good performance can be achieved with both analogue and digital voice systems, although the analogue system gives superior performance in fading. The results highlight the need for flexibility in the choice of signaling format. Linear transceiver technology capable of using many forms of narrowband modulation is described.

  6. Trellis-coded CPM for satellite-based mobile communications

    Science.gov (United States)

    Abrishamkar, Farrokh; Biglieri, Ezio

    1988-01-01

    Digital transmission for satellite-based land mobile communications is discussed. To satisfy the power and bandwidth limitations imposed on such systems, a combination of trellis coding and continuous-phase modulated signals are considered. Some schemes based on this idea are presented, and their performance is analyzed by computer simulation. The results obtained show that a scheme based on directional detection and Viterbi decoding appears promising for practical applications.

  7. Simobiz-Simulation Tool to Study the Impact of Small Satellites in Mobile Market

    Science.gov (United States)

    Burlacu, M.-M.; Kohlenberg, J.; Prathaban, M.

    2008-08-01

    Interest in small satellites is growing fast world- wide. Businesses, governments, universities and other organizations around the world are starting their own small satellite programs. The surveys conducted by the space agencies and universities shows a promising increase in the use of small satellites for commercial applications. More number of operators offers or plans to offer mobile phone services by satellite. With the help of cost effective small satellite, mobile operators can be able to provide the services cheaper. Hence, it is always interesting to study the effect of low cost small satellite over the mobile market. In this article, we present SmartSim (Small Satellites Mobile Market Simulator) - the new module of Simobiz business simulation game, in which we have implemented two operators, a normal satellite operator and a nanosatellite operator, with specific terminals and services. Our main focus in this work is to understand the future market of small satellite in mobile telecommunication network.

  8. Land-mobile-satellite fade measurements in Australia

    Science.gov (United States)

    Vogel, Wolfhard J.; Goldhirsh, Julius; Hase, Yoshihiro

    1992-01-01

    Attenuation measurements were implemented at L-band (1.5 GHz) in southeastern Australia during an 11-day period in October 1988 as part of a continuing examination of the propagation effects due to roadside trees and terrain for mobile-satellite service. Beacon transmissions from the geostationary ETS-V and IPORS satellites were observed. The Australian campaign expanded to another continent our Mobile Satellite Service data base of measurements executed in the eastern and southwestern United States regions. An empirical fade distribution model based on U.S. data predicted the Australian results with errors generally less than 1 dB in the 1-20 percent probability region. Directive antennas are shown to suffer deeper fades under severe shadowing conditions (3 dB excess at 4 percent), the equal-probability isolation between co- and cross-polarized transmissions deteriorated to 10 dB at the 5 dB fade level, and antenna diversity reception may reduce unavailability of the system by a factor of 2-8.

  9. Geodetic Mobil Solar Spectrometer for JASON Altimeter Satellite Calibration

    Science.gov (United States)

    Somieski, A.; Buerki, B.; Geiger, A.; Kahle, H.-G.; Becker-Ross, H.; Florek, S.; Okruss, M.

    Atmospheric water vapor is a crucial factor in achieving highest accuracies for space geodetic measurements. Water vapor causes a delay of the propagation time of the altimeter satellite signal, which propagates into errors for the determination of surface heights. Knowledge of the precipitable water vapor (PW) enables a tropospheric correction of the satellite signal. Therefore, different remote sensing techniques have been pursued to measure the PW continuously. The prototype Geodetic Mobil Solar Spectrometer (GEMOSS) was developed at the Geodesy and Geodynamics Laboratory (GGL, ETH Zurich) in cooperation with the Institute of Spectrochemistry and Applied Spectroscopy (ISAS) (Berlin, Germany). A new optical approach allows the simultaneous measurement of numerous single absorption lines of water vapor in the wide range between 728 nm and 915 nm. The large number of available absorption lines increases the accuracy of the absolute PW retrievals considerably. GEMOSS has been deployed during two campaigns in Greece in the framework of the EU-project GAVDOS, which deals with the calibration of the altimeter satellite JASON. During the overfly of JASON, the ground-based determination of PW enables the correction of the satellite measurements due to tropospheric water vapor. Comparisons with radiometer and radiosondes data allow to assess the accuracy and reliability of GEMOSS. The instrumental advancement of GEMOSS is presented together with the results of the campaigns carried out.

  10. Handoff algorithm for mobile satellite systems with ancillary terrestrial component

    KAUST Repository

    Sadek, Mirette

    2012-06-01

    This paper presents a locally optimal handoff algorithm for integrated satellite/ground communication systems. We derive the handoff decision function and present the results in the form of tradeoff curves between the number of handoffs and the number of link degradation events in a given distance covered by the mobile user. This is a practical receiver-controlled handoff algorithm that optimizes the handoff process from a user perspective based on the received signal strength rather than from a network perspective. © 2012 IEEE.

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

    Science.gov (United States)

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

    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.

  12. Evaluation of voice codecs for the Australian mobile satellite system

    Science.gov (United States)

    Bundrock, Tony; Wilkinson, Mal

    1990-01-01

    The evaluation procedure to choose a low bit rate voice coding algorithm is described for the Australian land mobile satellite system. The procedure is designed to assess both the inherent quality of the codec under 'normal' conditions and its robustness under 'severe' conditions. For the assessment, normal conditions were chosen to be random bit error rate with added background acoustic noise and the severe condition is designed to represent burst error conditions when mobile satellite channel suffers from signal fading due to roadside vegetation. The assessment is divided into two phases. First, a reduced set of conditions is used to determine a short list of candidate codecs for more extensive testing in the second phase. The first phase conditions include quality and robustness and codecs are ranked with a 60:40 weighting on the two. Second, the short listed codecs are assessed over a range of input voice levels, BERs, background noise conditions, and burst error distributions. Assessment is by subjective rating on a five level opinion scale and all results are then used to derive a weighted Mean Opinion Score using appropriate weights for each of the test conditions.

  13. Video Streaming Transfer in a Smart Satellite Mobile Environment

    Directory of Open Access Journals (Sweden)

    Nedo Celandroni

    2009-01-01

    satellite link for transmitting video streams to a bus, where they are relayed to passengers' devices. We say that a bus works in smart mode if it takes advantage of the knowledge of the exact points where fixed obstacles will prevent receiving the satellite signal for a certain time period. This information is sent to the hub via a return channel. The hub, in its turn, suspends the transmissions to that specific bus for the given time interval, thus avoiding information losses and unnecessary bandwidth occupation. Buffering video packets, without any quality of service (QoS degradation, seamlessly compensates channel blockages up to a given duration. We determine the most appropriate transmission parameters for video streaming with good video QoS in a mobile satellite environment; moreover, we evaluate how “smart” the system can be in terms of bandwidth saving, by comparing it with the situation where the bus does not exploit the description of its route, still maintaining the same QoS requirements.

  14. FQPSK techniques for satellite and mobile radio communications systems

    Science.gov (United States)

    Li, Yazhuo; Tang, Jing; Tao, Xiaofeng

    2005-11-01

    A continuous phase modulation (CPM) and constant envelope modulation (CEM) alternative of Feher-Patented quadrature phase-shift keying (FQPSK) modulation technique is presented. It is found to provide good spectral efficiencies, power efficiencies, and bit error rate (BER) performance. The modulation schemes of FQPSK are described. The spectral efficiencies, BER performance are also compared with FQPSK and other modulation techniques which are widely used in current mobile and cordless radio standards. The results show that FQPSK modulated signal exhibits much less spectrum spreading than QPSK, OQPSK, and MSK, and the error probability performance of the FQPSK is superior to those in narrow-band nonlinear channels. Based on that, the system capacity and power dissipation are also analyzed for communication systems. It is found that the encoder or receiver for the FQPSK signal to be fully compatible with original I/Q modulated one. FQPSK technique is suitable for nonlinear channels, such as satellite and mobile communications systems reducing the AM/AM and AM/PM adverse effects. At last it is also attempted to extend the application in 3G (CDMA) and 4G (OFDM) mobile communications systems.

  15. Proceedings of the Seventeenth NASA Propagation Experimenters Meeting (NAPEX 17) and the Advanced Communications Technology Satellite (ACTS) Propagation Studies Miniworkshop

    Science.gov (United States)

    Davarian, Faramaz (Editor)

    1993-01-01

    The NASA Propagation Experimenters Meeting (NAPEX) is convened annually to discuss studies made on radio wave propagation by investors from domestic and international organizations. NAPEX 17 was held on 15 June 1993. The meeting was organized into two technical sessions. The first session was dedicated to slant path propagation studies and experiments. The second session focused on propagation studies for mobile and personal communications. Preceding NAPEX 17, the Advanced Communications Technology Satellite (ACTS) Propagation Studies Miniworkshop was held on 14 June 1993 to review ACTS propagation activities with emphasis on ACTS experiments status and data collection, processing, and exchange.

  16. Considerations of digital phase modulation for narrowband satellite mobile communication

    Science.gov (United States)

    Grythe, Knut

    1990-01-01

    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.

  17. Application of SAW technology in satellites for mobile services

    Science.gov (United States)

    Andreassen, O.; Viddal, V.; Galteland, J.

    1990-03-01

    Two surface acoustic wave (SAW) technologies for IF processing in a mobile satellite are discussed. The components and operations of the SAW filters method and the SAW filtering, routing, and beamforming concept are described. The capabilities of these two concepts are evaluated and compared. It is observed that the use of SAW filters is the more conventional and mature technology; it performs the channelizing function with a bank of SAW filters and routing of these channels by a switch matrix arrangement. The SAW filtering, routing, and beamforming concept is a more advanced technology that has the ability to give high resolution at low cost in volume and power; however, it has a high power consumption at large total processed bandwidth.

  18. Medium-rate speech coding simulator for mobile satellite systems

    Science.gov (United States)

    Copperi, Maurizio; Perosino, F.; Rusina, F.; Albertengo, G.; Biglieri, E.

    1986-01-01

    Channel modeling and error protection schemes for speech coding are described. A residual excited linear predictive (RELP) coder for bit rates 4.8, 7.2, and 9.6 kbit/sec is outlined. The coder at 9.6 kbit/sec incorporates a number of channel error protection techniques, such as bit interleaving, error correction codes, and parameter repetition. Results of formal subjective experiments (DRT and DAM tests) under various channel conditions, reveal that the proposed coder outperforms conventional LPC-10 vocoders by 2 subjective categories, thus confirming the suitability of the RELP coder at 9.6 kbit/sec for good quality speech transmission in mobile satellite systems.

  19. A European mobile satellite system concept exploiting CDMA and OBP

    Science.gov (United States)

    Vernucci, A.; Craig, A. D.

    1993-01-01

    This paper describes a novel Land Mobile Satellite System (LMSS) concept applicable to networks allowing access to a large number of gateway stations ('Hubs'), utilizing low-cost Very Small Aperture Terminals (VSAT's). Efficient operation of the Forward-Link (FL) repeater can be achieved by adopting a synchronous Code Division Multiple Access (CDMA) technique, whereby inter-code interference (self-noise) is virtually eliminated by synchronizing orthogonal codes. However, with a transparent FL repeater, the requirements imposed by the highly decentralized ground segment can lead to significant efficiency losses. The adoption of a FL On-Board Processing (OBP) repeater is proposed as a means of largely recovering this efficiency impairment. The paper describes the network architecture, the system design and performance, the OBP functions and impact on implementation. The proposed concept, applicable to a future generation of the European LMSS, was developed in the context of a European Space Agency (ESA) study contract.

  20. Adaptive beamforming in a CDMA mobile satellite communications system

    Science.gov (United States)

    Munoz-Garcia, Samuel G.

    1993-01-01

    Code-Division Multiple-Access (CDMA) stands out as a strong contender for the choice of multiple access scheme in these future mobile communication systems. This is due to a variety of reasons such as the excellent performance in multipath environments, high scope for frequency reuse and graceful degradation near saturation. However, the capacity of CDMA is limited by the self-interference between the transmissions of the different users in the network. Moreover, the disparity between the received power levels gives rise to the near-far problem, this is, weak signals are severely degraded by the transmissions from other users. In this paper, the use of time-reference adaptive digital beamforming on board the satellite is proposed as a means to overcome the problems associated with CDMA. This technique enables a high number of independently steered beams to be generated from a single phased array antenna, which automatically track the desired user signal and null the unwanted interference sources. Since CDMA is interference limited, the interference protection provided by the antenna converts directly and linearly into an increase in capacity. Furthermore, the proposed concept allows the near-far effect to be mitigated without requiring a tight coordination of the users in terms of power control. A payload architecture will be presented that illustrates the practical implementation of this concept. This digital payload architecture shows that with the advent of high performance CMOS digital processing, the on-board implementation of complex DSP techniques -in particular digital beamforming- has become possible, being most attractive for Mobile Satellite Communications.

  1. Flat Array Antennas for Ku-Band Mobile Satellite Terminals

    Directory of Open Access Journals (Sweden)

    Roberto Vincenti Gatti

    2009-01-01

    Full Text Available This work presents the advances in the development of two innovative flat array antennas for Ku-band mobile satellite terminals. The first antenna is specifically conceived for double-deck trains to allow a bi-directional high data rate satellite link. The available circular surface (diameter 80 cm integrates both a transmitting and a receiving section, operating in orthogonal linear polarizations. The TX frequency range is fully covered while the RX bandwidth is around 1 GHz arbitrarily allocated on the DVB range depending on requirements. The beam is steered in elevation through a phased array architecture not employing costly phase shifters, while the steering in azimuth is mechanical. Active BFNs allow excellent performance in terms of EIRP and G/T, maintaining extremely low profile. High antenna efficiency and low fabrication cost are ensured by the employment of innovative SIW (Substrate Integrated Waveguide structures. The second antenna, receiving-only, is designed for radio/video streaming services in mobile environment. Full DVB coverage is achieved thanks to cavity-backed patches operating in double linear polarization. Two independent broadband active BFNs allow simultaneous reception of both polarizations with full tracking capabilities and a squintless beam steering from 20∘ to 60∘ in elevation. A minimum gain of 20 dBi and G/T >−3 dB/∘K are achieved, while maintaining extremely compact size and flat profile. In the design of both antennas fabrication cost is considered as a driving factor, yet providing high performance with a flat profile and thus resulting in a great commercial potentiality.

  2. Integration between terrestrial-based and satellite-based land mobile communications systems

    Science.gov (United States)

    Arcidiancono, Antonio

    A survey is given of several approaches to improving the performance and marketability of mobile satellite systems (MSS). The provision of voice/data services in the future regional European Land Mobile Satellite System (LMSS), network integration between the Digital Cellular Mobile System (GSM) and LMSS, the identification of critical areas for the implementation of integrated GSM/LMSS areas, space segment scenarios, LMSS for digital trunked private mobile radio (PMR) services, and code division multiple access (CDMA) techniques for a terrestrial/satellite system are covered.

  3. Integration between terrestrial-based and satellite-based land mobile communications systems

    Science.gov (United States)

    Arcidiancono, Antonio

    1990-01-01

    A survey is given of several approaches to improving the performance and marketability of mobile satellite systems (MSS). The provision of voice/data services in the future regional European Land Mobile Satellite System (LMSS), network integration between the Digital Cellular Mobile System (GSM) and LMSS, the identification of critical areas for the implementation of integrated GSM/LMSS areas, space segment scenarios, LMSS for digital trunked private mobile radio (PMR) services, and code division multiple access (CDMA) techniques for a terrestrial/satellite system are covered.

  4. International organizations to enable world-wide mobile satellite services

    Science.gov (United States)

    Anglin, Richard L., Jr.

    1993-01-01

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

  5. A satellite-tracking millimeter-wave reflector antenna system for mobile satellite-tracking

    Science.gov (United States)

    Densmore, Arthur C. (Inventor); Jamnejad, Vahraz (Inventor); Woo, Kenneth E. (Inventor)

    1995-01-01

    A miniature dual-band two-way mobile satellite tracking antenna system mounted on a movable ground vehicle includes a miniature parabolic reflector dish having an elliptical aperture with major and minor elliptical axes aligned horizontally and vertically, respectively, to maximize azimuthal directionality and minimize elevational directionality to an extent corresponding to expected pitch excursions of the movable ground vehicle. A feed-horn has a back end and an open front end facing the reflector dish and has vertical side walls opening out from the back end to the front end at a lesser horn angle and horizontal top and bottom walls opening out from the back end to the front end at a greater horn angle. An RF circuit couples two different signal bands between the feed-horn and the user. An antenna attitude controller maintains an antenna azimuth direction relative to the satellite by rotating it in azimuth in response to sensed yaw motions of the movable ground vehicle so as to compensate for the yaw motions to within a pointing error angle. The controller sinusoidally dithers the antenna through a small azimuth dither angle greater than the pointing error angle while sensing a signal from the satellite received at the reflector dish, and deduces the pointing angle error from dither-induced fluctuations in the received signal.

  6. Satellite-Tracking Millimeter-Wave Reflector Antenna System For Mobile Satellite-Tracking

    Science.gov (United States)

    Densmore, Arthur C. (Inventor); Jamnejad, Vahraz (Inventor); Woo, Kenneth E. (Inventor)

    2001-01-01

    A miniature dual-band two-way mobile satellite-tracking antenna system mounted on a movable vehicle includes a miniature parabolic reflector dish having an elliptical aperture with major and minor elliptical axes aligned horizontally and vertically, respectively, to maximize azimuthal directionality and minimize elevational directionality to an extent corresponding to expected pitch excursions of the movable ground vehicle. A feed-horn has a back end and an open front end facing the reflector dish and has vertical side walls opening out from the back end to the front end at a lesser horn angle and horizontal top and bottom walls opening out from the back end to the front end at a greater horn angle. An RF circuit couples two different signal bands between the feed-horn and the user. An antenna attitude controller maintains an antenna azimuth direction relative to the satellite by rotating it in azimuth in response to sensed yaw motions of the movable ground vehicle so as to compensate for the yaw motions to within a pointing error angle. The controller sinusoidally dithers the antenna through a small azimuth dither angle greater than the pointing error angle while sensing a signal from the satellite received at the reflector dish, and deduces the pointing angle error from dither-induced fluctuations in the received signal.

  7. Design and implementation of an experiment scheduling system for the ACTS satellite

    Science.gov (United States)

    Ringer, Mark J.

    1994-01-01

    The Advanced Communication Technology Satellite (ACTS) was launched on the 12th of September 1993 aboard STS-51. All events since that time have proceeded as planned with user operations commencing on December 6th, 1993. ACTS is a geosynchronous satellite designed to extend the state of the art in communication satellite design and is available to experimenters on a 'time/bandwidth available' basis. The ACTS satellite requires the advance scheduling of experimental activities based upon a complex set of resource, state, and activity constraints in order to ensure smooth operations. This paper describes the software system developed to schedule experiments for ACTS.

  8. K-band mobile propagation measurements using ACTS

    Science.gov (United States)

    Goldhirsh, Julius; Vogel, Wolfhard J.; Torrence, Geoffrey W.

    1993-01-01

    An overview of two planned propagation campaigns employing land-mobile scenarios with ACTS is presented. The campaigns will be undertaken through a joint effort involving the Johns Hopkins University, Applied Physics Laboratory (APL), The University of Texas at Austin, Electrical Engineering Research Laboratory (EERL), and the NASA Lewis Research Center (NASA LeRC). Propagation campaigns are planned in Central Maryland in November 1993 (elevation angle approx. equals 40 deg.) and in Fairbanks, Alaska in June 1994 (elevation angle approx. equals 8 deg.) employing a computer controlled antenna tracking system located atop a van containing a receiver/data acquisition system. The antenna will track (in azimuth) downlink transmissions at 19.914 GHz from ACTS during the mobile propagation measurements. The major objectives of the campaigns are to measure the fade and multipath effects of trees and terrain at 20 GHz for rural and suburban scenarios and to extend existing models which were previously validated at UHF to S-Band.

  9. Mobile satellite news gathering (SNG) system; Soko SNG (Satellite News Gathering) shasaikyoku

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2000-03-01

    Commercialization was made for broadcasting stations on a mobile station system capable of capturing a satellite automatically while the system is moving. Its feature is the enhanced tracking accuracy as a result of using the Company's original null-sensor (see Note), and detecting and controlling intersecting polarized waves of reference signals from the satellite. The material for transmission is digitally transmitted by MPEG2, making it possible to transmit more data than by conventional systems. The system is being used for live broadcasting of marathon races and emergency news broadcasting. It is expected that the system may be applied to applications other than broadcasting stations, such as automobiles and ships. (Note: A null-sensor is a unit used for adjusting antenna directions for an SNG transmitter. It uses IF receiving signals of H/V polarized waves of parabolic antenna as an input, and outputs the main polarized wave level and the intersecting polarized wave level.) (translated by NEDO)

  10. Neural Network Based Lna Design for Mobile Satellite Receiver

    Directory of Open Access Journals (Sweden)

    Abhijeet Upadhya

    2014-08-01

    Full Text Available Paper presents a Neural Network Modelling approach to microwave LNA design. To acknowledge the specifications of the amplifier, Mobile Satellite Systems are analyzed. Scattering parameters of the LNA in the frequency range 0.5 to 18 GHz are calculated using a Multilayer Perceptron Artificial Neural Network model and corresponding smith charts and polar charts are plotted as output to the model. From these plots, the microwave scattering parameter description of the LNA are obtained. Model is efficiently trained using Agilent ATF 331M4 InGaAs/InP Low Noise pHEMT amplifier datasheet and the neural model’s output seem to follow the various device characteristic curves with high regression. Next, Maximum Allowable Gain and Noise figure of the device are modelled and plotted for the same frequency range. Finally, the optimized model is utilized as an interpolator and the resolution of the amplifying capability with noise characteristics are obtained for the L Band of MSS operation.

  11. Microstrip Yagi array antenna for mobile satellite vehicle application

    Science.gov (United States)

    Huang, John; Densmore, Arthur C.

    1991-01-01

    A novel antenna structure formed by combining the Yagi-Uda array concept and the microstrip radiator technique is discussed. This antenna, called the microstrip Yagi array, has been developed for the mobile satellite (MSAT) system as a low-profile, low-cost, and mechanically steered medium-gain land-vehicle antenna. With the antenna's active patches (driven elements) and parasitic patches (reflector and director elements) located on the same horizontal plane, the main beam of the array can be tilted, by the effect of mutual coupling, in the elevation direction providing optimal coverage for users in the continental United States. Because the parasitic patches are not connected to any of the lossy RF power distributing circuit the antenna is an efficient radiating system. With the complete monopulse beamforming and power distributing circuits etched on a single thin stripline board underneath the microstrip Yagi array, the overall L-band antenna system has achieved a very low profile for vehicle's rooftop mounting, as well as a low manufacturing cost. Experimental results demonstrate the performance of this antenna.

  12. Mobile user environment and satellite diversity for NGSO S-PCN's

    Science.gov (United States)

    Werner, Markus; Bischl, Hermann; Lutz, Erich

    1995-01-01

    The performance of satellite diversity under the influence of the mobile user environment is analyzed. To this end, a digital channel model is presented which takes into account the elevation angle as well as the user mobility in a given environment. For different LEO and MEO systems and for varying mobile user environments, some crucial benefits and drawbacks of satellite diversity are discussed. Specifically, the important GW service area concept is introduced. The conclusions are validated by numerical results from computer simulations. Globalstar (LEO) and Inmarsat (MEO) are compared in terms of visibility, service availability and equivalent handover complexity for different environments and user mobility.

  13. A system architecture for an advanced Canadian wideband mobile satellite system

    Science.gov (United States)

    Takats, P.; Keelty, M.; Moody, H.

    In this paper, the system architecture for an advanced Canadian ka-band geostationary mobile satellite system is described, utilizing hopping spot beams to support a 256 kbps wideband service for both N-ISDN and packet-switched interconnectivity to small briefcase-size portable and mobile terminals. An assessment is given of the technical feasibility of the satellite payload and terminal design in the post year 2000 timeframe. The satellite payload includes regeneration and on-board switching to permit single hop interconnectivity between mobile terminals. The mobile terminal requires antenna tracking and platform stabilization to ensure acquisition of the satellite signal. The potential user applications targeted for this wideband service includes: home-office, multimedia, desk-top (PC) videoconferencing, digital audio broadcasting, single and multi-user personal communications.

  14. A discussion on mobile satellite system and the myths of CDMA and diversity revealed

    Science.gov (United States)

    Hart, Nicholas; Goerke, Thomas; Jahn, Axel

    1995-01-01

    The paper explores the myths and facts surrounding: link margins and constellation designs; the use of satellite diversity in a mobile satellite channel; trade-offs in multiple access technique. Different satellite constellations are presented, which are comparable with those used by the big LEO proponents, with the associated trade-offs in the system design. Propagation data and results from various narrowband and wideband measurement campaigns are used to illustrate the expected differences in service performance.

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

    Science.gov (United States)

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

    1993-01-01

    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.

  16. A satellite orbital testbed for SATCOM using mobile robots

    Science.gov (United States)

    Shen, Dan; Lu, Wenjie; Wang, Zhonghai; Jia, Bin; Wang, Gang; Wang, Tao; Chen, Genshe; Blasch, Erik; Pham, Khanh

    2016-05-01

    This paper develops and evaluates a satellite orbital testbed (SOT) for satellite communications (SATCOM). SOT can emulate the 3D satellite orbit using the omni-wheeled robots and a robotic arm. The 3D motion of satellite is partitioned into the movements in the equatorial plane and the up-down motions in the vertical plane. The former actions are emulated by omni-wheeled robots while the up-down motions are performed by a stepped-motor-controlled-ball along a rod (robotic arm), which is attached to the robot. The emulated satellite positions will go to the measure model, whose results will be used to perform multiple space object tracking. Then the tracking results will go to the maneuver detection and collision alert. The satellite maneuver commands will be translated to robots commands and robotic arm commands. In SATCOM, the effects of jamming depend on the range and angles of the positions of satellite transponder relative to the jamming satellite. We extend the SOT to include USRP transceivers. In the extended SOT, the relative ranges and angles are implemented using omni-wheeled robots and robotic arms.

  17. 75 FR 80354 - Satellite Television Extension and Localism Act of 2010 and Satellite Home Viewer Extension and...

    Science.gov (United States)

    2010-12-22

    ... Extension and Reauthorization Act of 2004 AGENCY: Federal Communications Commission. ACTION: Final rule... in the TV bands where unlicensed devices could operate as it is beyond the scope of this proceeding... are much different than those faced by satellite signals, which travel over paths that are...

  18. Global mobile satellite communications theory for maritime, land and aeronautical applications

    CERN Document Server

    Ilčev, Stojče Dimov

    2017-01-01

    This book discusses current theory regarding global mobile satellite communications (GMSC) for maritime, land (road and rail), and aeronautical applications. It covers how these can enable connections between moving objects such as ships, road and rail vehicles and aircrafts on one hand, and on the other ground telecommunications subscribers through the medium of communications satellites, ground earth stations, Terrestrial Telecommunication Networks (TTN), Internet Service Providers (ISP) and other wireless and landline telecommunications providers. This new edition covers new developments and initiatives that have resulted in land and aeronautical applications and the introduction of new satellite constellations in non-geostationary orbits and projects of new hybrid satellite constellations. The book presents current GMSC trends, mobile system concepts and network architecture using a simple mode of style with understandable technical information, characteristics, graphics, illustrations and mathematics equ...

  19. Mobile access to the Internet: from personal bubble to satellites

    Science.gov (United States)

    Gerla, Mario

    2001-10-01

    Mobile, wireless access and networking has emerged in the last few years as one of the most important directions of Internet growth. The popularity of mobile, and, more generally, nomadic Internet access is due to many enabling factors including: (a) emergence of meaningful applications tailored to the individual on the move; (b) small form factor and long battery life; (c) efficient middleware designed to support mobility; and, (d) efficient wireless networking technologies. A key player in the mobile Internet access is the nomad, i.e. the individual equipped with various computing and I/O gadgets (cellular phone, earphones, GPS navigator, palm pilot, beeper, portable scanner, digital camera, etc.). These devices form his/her Personal Area Network or PAN or personal bubble. The connectivity within the bubble is wireless (using for example a low cost, low power wireless LAN such as Bluetooth). The bubble can expand and contract dynamically depending on needs. It may temporarily include sensors and actuators as the nomad walks into a new environment. In this paper, we identify the need for the interconnection of the PAN with other wireless networks in order to achieve costeffective mobile access to the Internet. We will overview some key networking technologies required to support the PAN (eg, Bluetooth). We will also discuss an emerging technology, Ad Hoc wireless networking which is the natural complement of the PAN in sparsely populated areas. Finally, we will identify the need for intelligent routers to assist the mobile user in the selection of the best Internet access strategy.

  20. Mobile radio alternative systems study satellite/terrestrial (hybrid) systems concepts

    Science.gov (United States)

    Kiesling, J. D.; Anderson, R. E.

    1983-01-01

    The use of satellites for mobile radio service in non-urban areas of the United States in the years from 1985 to 2000 was investigated. Several satellite concepts are considered: a system with single-beam coverage of the fifty United States and Puerto Rico, and multi-beam satellites with greater capacity. All of the needed functions and services identified in the market study are provided by the satellite systems, including nationwide radio access to vehicles without knowledge of vehicle location wideband data transmission from remote sites, two way exchange of short data and control messages between vehicles and dispatch or control centers, and automatic vehicle location (surveillance). The costs of providing the services are within acceptable limits, and the desired returns to the system investors are attractive. The criteria by which the Federal Communication judges the competing demands for public radio spectrum are reviewed with comments on how the criteria might apply to the consideration of land mobile satellites. Institutional arrangements for operating a mobile satellite system are based on the present institutional arrangements in which the services are offered to the end users through wireline and radio common carriers, with direct access by large private and government users.

  1. Potential markets for a satellite-based mobile communications system

    Science.gov (United States)

    Jamieson, W. M.; Peet, C. S.; Bengston, R. J.

    1976-01-01

    The objective of the study was to define the market needs for improved land mobile communications systems. Within the context of this objective, the following goals were set: (1) characterize the present mobile communications industry; (2) determine the market for an improved system for mobile communications; and (3) define the system requirements as seen from the potential customer's viewpoint. The scope of the study was defined by the following parameters: (1) markets were confined to U.S. and Canada; (2) range of operation generally exceeded 20 miles, but this was not restrictive; (3) the classes of potential users considered included all private sector users, and non-military public sector users; (4) the time span examined was 1975 to 1985; and (5) highly localized users were generally excluded - e.g., taxicabs, and local paging.

  2. Advanced Communications Technology Satellite (ACTS). Phase 1: Industrial/academic experimenters

    Science.gov (United States)

    Maisel, James E.; Nowlin, Robert W.

    1992-01-01

    This report presents the work done at Arizona State University under the ACTS Experimenters Program. The main thrust of the Program was to develop experiments to test, evaluate, and prove the commercial worthiness of the ACTS satellite which is scheduled for launch in 1993. To accomplish this goal, meetings were held with various governmental, industrial, and academic units to discuss the ACTS satellite and its technology and possible experiments that would generate industrial interest and support for ASU's efforts. Several local industries generated several experiments of their own. The investigators submitted several experiments of educational, medical, commercial, and technical value and interest. The disposition of these experimental proposals is discussed in this report.

  3. Terminal-to-Terminal Calling for GEO Broadband Mobile Satellite Communication

    Institute of Scientific and Technical Information of China (English)

    Jinsheng Yang

    2015-01-01

    Satellite and terrestrial components of IMT⁃Advanced need to be integrated so that the traditional strengths of each compo⁃nent can be fully exploited. LTE/LTE⁃A is now a recognized foundation of terrestrial 4G networks, and mobile satellite net⁃works should be based on it. Long transmission delay is one of the main disadvantages of satellite communication, espe⁃cially in a GEO system, and terminal⁃to⁃terminal (TtT) design reduces this delay. In this paper, we propose a protocol archi⁃tecture based on LTE/LTE⁃A for GEO mobile satellite commu⁃nication. We propose a detailed call procedure and four TtT modes for this architecture. We describe the division of tasks between the satellite gateway (SAT⁃GW) and satellite as well as TtT processing in the physical layer of the satellite in or⁃der to reduce delay and ensure compatibility with a terrestrial LTE/LTE⁃A system.

  4. Satellite-aided mobile communications limited operational test in the trucking industry

    Science.gov (United States)

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

    1980-01-01

    An experiment with NASA's ATS-6 satellite, that demonstrates the practicality of satellite-aided land mobile communications is described. Satellite communications equipment for the experiment was designed so that it would be no more expensive, when mass produced, than conventional two-way mobile radio equipment. It embodied the operational features and convenience of present day mobile radios. Vehicle antennas 75 cm tall and 2 cm in diameter provided good commercial quality signals to and from trucks and jeeps. Operational applicability and usage data were gathered by installing the radio equipment in five long-haul tractor-trailer trucks and two Air Force search and rescue jeeps. Channel occupancy rates are reported. Air Force personnel found the satellite radio system extremely valuable in their search and rescue mission during maneuvers and actual rescue operations. Propagation data is subjectively analyzed and over 4 hours of random data is categorized and graded as to signal quality on a second by second basis. Trends in different topographic regions are reported. An overall communications reliability of 93% was observed despite low satellite elevation angles ranging from 9 to 24 degrees.

  5. Steerable K/Ka-Band Antenna For Land-Mobile Satellite Applications

    Science.gov (United States)

    Densmore, Arthur; Jamnejad, Vahraz; Woo, Kenneth

    1994-01-01

    Prototype steerable microwave antenna tracks and communicates with geostationary satellite. Designed to mount on roof of vehicle and only 10 cm tall. K/Ka-band antenna rugged and compact to suit rooftop mobile operating environment. More-delicate signal-processing and control equipment located inside vehicle.

  6. Applications technology satellite F&G /ATS F&G/ mobile terminal.

    Science.gov (United States)

    Greenbaum, L. A.; Baker, J. L.

    1971-01-01

    The mobile terminal is a flexible, easily transportable system. The terminal design incorporates a combination of unique and proven hardware to provide maximum utility consistent with reliability. The flexibility built into the system will make it possible to satisfy the requirements of the applications technology satellite program concerned with the conduction of various spacecraft technology experiments. The terminal includes two parabolic antennas.

  7. Mapping poverty using mobile phone and satellite data

    Science.gov (United States)

    Pezzulo, Carla; Bjelland, Johannes; Iqbal, Asif M.; Hadiuzzaman, Khandakar N.; Lu, Xin; Wetter, Erik; Tatem, Andrew J.

    2017-01-01

    Poverty is one of the most important determinants of adverse health outcomes globally, a major cause of societal instability and one of the largest causes of lost human potential. Traditional approaches to measuring and targeting poverty rely heavily on census data, which in most low- and middle-income countries (LMICs) are unavailable or out-of-date. Alternate measures are needed to complement and update estimates between censuses. This study demonstrates how public and private data sources that are commonly available for LMICs can be used to provide novel insight into the spatial distribution of poverty. We evaluate the relative value of modelling three traditional poverty measures using aggregate data from mobile operators and widely available geospatial data. Taken together, models combining these data sources provide the best predictive power (highest r2 = 0.78) and lowest error, but generally models employing mobile data only yield comparable results, offering the potential to measure poverty more frequently and at finer granularity. Stratifying models into urban and rural areas highlights the advantage of using mobile data in urban areas and different data in different contexts. The findings indicate the possibility to estimate and continually monitor poverty rates at high spatial resolution in countries with limited capacity to support traditional methods of data collection. PMID:28148765

  8. Mapping poverty using mobile phone and satellite data.

    Science.gov (United States)

    Steele, Jessica E; Sundsøy, Pål Roe; Pezzulo, Carla; Alegana, Victor A; Bird, Tomas J; Blumenstock, Joshua; Bjelland, Johannes; Engø-Monsen, Kenth; de Montjoye, Yves-Alexandre; Iqbal, Asif M; Hadiuzzaman, Khandakar N; Lu, Xin; Wetter, Erik; Tatem, Andrew J; Bengtsson, Linus

    2017-02-01

    Poverty is one of the most important determinants of adverse health outcomes globally, a major cause of societal instability and one of the largest causes of lost human potential. Traditional approaches to measuring and targeting poverty rely heavily on census data, which in most low- and middle-income countries (LMICs) are unavailable or out-of-date. Alternate measures are needed to complement and update estimates between censuses. This study demonstrates how public and private data sources that are commonly available for LMICs can be used to provide novel insight into the spatial distribution of poverty. We evaluate the relative value of modelling three traditional poverty measures using aggregate data from mobile operators and widely available geospatial data. Taken together, models combining these data sources provide the best predictive power (highest r(2) = 0.78) and lowest error, but generally models employing mobile data only yield comparable results, offering the potential to measure poverty more frequently and at finer granularity. Stratifying models into urban and rural areas highlights the advantage of using mobile data in urban areas and different data in different contexts. The findings indicate the possibility to estimate and continually monitor poverty rates at high spatial resolution in countries with limited capacity to support traditional methods of data collection. © 2017 The Authors.

  9. A variable bandwidth assignment scheme for the Land Mobile Satellite experiment

    Science.gov (United States)

    Yan, T.-Y.; Li, V. O. K.

    The Mobile Satellite Experiment is a proposed experimental satellite-based communications network which provides data and voice communications to mobile terminals dispersed in geographically dispersed areas. In this paper, an analytical model is developed to calculate the performance of a Variable Bandwidth Assignment (VBA) Scheme. Under this scheme, the satellite channel bandwidth is dynamically reassigned so that a message may be transmitted in the shortest possible time. To transmit a long message, message channels will be reconfigured to have more bandwidth such that the transmission time is reduced, while to transmit a short message, the channel bandwidth will be shrunk such that the released bandwidth can be used to serve other messages. The model is illustrated with numerical examples. It is shown that a VBA scheme can achieve considerable improvement in transmission delays over a Fixed Bandwidth Assignment Scheme.

  10. Handover aspects for a Low Earth Orbit (LEO) CDMA Land Mobile Satellite (LMS) system

    Science.gov (United States)

    Carter, P.; Beach, M. A.

    1993-01-01

    This paper addresses the problem of handoff in a land mobile satellite (LMS) system between adjacent satellites in a low earth orbit (LEO) constellation. In particular, emphasis is placed on the application of soft handoff in a direct sequence code division multiple access (DS-CDMA) LMS system. Soft handoff is explained in terms of terrestrial macroscopic diversity, in which signals transmitted via several independent fading paths are combined to enhance the link quality. This concept is then reconsidered in the context of a LEO LMS system. A two-state Markov channel model is used to simulate the effects of shadowing on the communications path from the mobile to each satellite during handoff. The results of the channel simulation form a platform for discussion regarding soft handoff, highlighting the potential merits of the scheme when applied in a LEO LMS environment.

  11. The provision of spectrum for feeder links of non-geostationary mobile satellites

    Science.gov (United States)

    Bowen, Robert R.

    1993-01-01

    The possibility of sharing spectrum in the 30/20 GHz band between geostationary fixed-satellite systems and feeder-links of low-earth orbit (LEO) mobile-satellite systems is addressed, taking into account that International Telecommunications Union (ITU) Radio Regulation 2613 would be a factor in such sharing. Interference into each network in both the uplink at 30 GHz and the downlink at 20 GHz is considered. It is determined that if sharing were to take place the mobile-satellite may have to cease transmission often for intervals up to 10 seconds, may have to use high-gain tracking antennas on its spacecraft, and may find it an advantage to use code-division multiple access. An alternate solution suggested is to designate a band 50 to 100 MHz wide at 28 and 18 GHz to be used primarily for feeder links to LEO systems.

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

    Science.gov (United States)

    Naderi, F. (Editor)

    1982-01-01

    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.

  13. An advanced generation land mobile satellite system and its critical technologies

    Science.gov (United States)

    Naderi, F.

    1982-01-01

    A conceptual design for a Land Mobile Satellite System (LMSS) for the 1990s is presented. LMSS involves small tranceivers accessing satellites directly, with ground reception through small car-top antennas. The satellite would have a large antenna and blanket coverage areas in the UHF. The call may originate from a home, be carried by wire to a gateway, transmitted to satellite on the S-band, converted to UHF on the satellite, and transmitted to the vehicle. The system design is constrained by the number of users in an area during the busiest hours, Shuttle storage, controllability factors, and the total area served. A 55-m antenna has been selected, with 87 spot beams and two 10 MHz UHF bands in the 806-890 MHz band. A 17 dB interbeam isolation level is required, implying that sufficient sub-bands can be generated to assure 8265 total channels. The mobile satellite (MSAT) would have an 83 m mast lower segment, a 34 m upper segment, and a second, 10 m antenna made of a deployable mesh. Various antenna function modes are considered.

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

    Science.gov (United States)

    Freibaum, Jerry

    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.

  15. Aviation-oriented Mobility Management Method in IP/LEO Satellite Networks

    Institute of Scientific and Technical Information of China (English)

    Guo Xin; Zhang Jun; Zhang Tao; Ding Yanwen

    2008-01-01

    Taking into chief consideration the features of aviation nodes in satellite networks,such as high moving speed,long communication distance,and high connection frequency,this article proposes an aviatiun-oriented mobility management method for IP/low earth orbit (LEO) satellite networks.By introducing the concept of ground station real-time coverage area,the proposed method uses ground-station-based IP addressing method and cell paging scheme to decrease the frequency of IP binding update requests as well as the paging cost.In comparison with the paging mobile IP (P-MIP) method and the handover-independent IP mobility management method,as is verified by the mathematical analysis and simulation,the proposed method could decrease the management cost.It also possesses better ability to support the aviation nodes because it is subjected to fewer influences from increased node speeds and newly coming connection rates.

  16. A study and experiment plan for digital mobile communication via satellite

    Science.gov (United States)

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

    1978-01-01

    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 quality speech. A traffic model is derived on which to base the determination of the required maximum number of satellite channels to provide the anticipated level of service. Various voice digitalization and digital modulation schemes are reviewed along with a general link analysis of the mobile system. Demand assignment multiple access considerations and analysis tradeoffs are presented. Finally, a completed configuration is described.

  17. System architecture and market aspects of an European Land Mobile Satellite System via EMS

    Science.gov (United States)

    Ananasso, F.; Mistretta, I.

    1992-03-01

    The paper describes an implementation scenario of a Land Mobile Satellite System via the EMS (European Mobile System) payload embarked on Italsat F-2. Some emphasis is given on market issues aiming at singling out business niches of Land Mobile Satellite Services (LMSS) in Europe. Other crucial issues exist such as: the alternate/competitive systems, the problems of interworking with other existing and/or planned systems, the definition of network architecture that better fits the user requirements, the marketing strategy and, last but not least, the financial evaluation of the project. The paper, on the basis of a study performed by Telespazio on behalf of ESA, discusses some of these issues with emphasis on competitive market aspects.

  18. Computational Research on Mobile Pastoralism Using Agent-Based Modeling and Satellite Imagery.

    Directory of Open Access Journals (Sweden)

    Takuto Sakamoto

    Full Text Available Dryland pastoralism has long attracted considerable attention from researchers in diverse fields. However, rigorous formal study is made difficult by the high level of mobility of pastoralists as well as by the sizable spatio-temporal variability of their environment. This article presents a new computational approach for studying mobile pastoralism that overcomes these issues. Combining multi-temporal satellite images and agent-based modeling allows a comprehensive examination of pastoral resource access over a realistic dryland landscape with unpredictable ecological dynamics. The article demonstrates the analytical potential of this approach through its application to mobile pastoralism in northeast Nigeria. Employing more than 100 satellite images of the area, extensive simulations are conducted under a wide array of circumstances, including different land-use constraints. The simulation results reveal complex dependencies of pastoral resource access on these circumstances along with persistent patterns of seasonal land use observed at the macro level.

  19. NASA ACTS Multibeam Antenna (MBA) System. [Advanced Communications Technology Satellite

    Science.gov (United States)

    Choung, Youn H.; Stiles, W. Herschel; Wu, Joseph; Wong, William C.; Chen, C. Harry

    1986-01-01

    The design of the Advanced Communications Technology Satellite MBA system, which provides both spot beam and scanning beam coverage to both high and low burst rates data-users is examined. The MBA consists of receive and transmit antennas installed on a common precision mounting platform that is integrated to the bus through three flexures; a lightweight system with low thermal distortion is obtained by using composite materials for the MBA structures. The RF design, which is a Cassegrain reflector with a large equivalent focal length/aperture size, is described. Consideration is given to the position of the feed in order to minimize scan loss and sidelobe levels, the size of the subreflector in order to minimize feed spillover, and antenna performance degradation caused by reflector surface distortion. Breadbroad model test result reveal that the maximum sidelobe level outside the 2.5 HPBW region is -30 dB or lower relative to the power.

  20. Second-generation mobile satellite system. A conceptual design and trade-off study

    Science.gov (United States)

    Sue, M. K.; Park, Y. H.

    1985-01-01

    In recent years, interest has grown in the mobile satellite (MSAT) system, a satellite-based communications system capable of providing integrated voice and data services to a large number of users. To explore the potential of a commercial mobile satellite system (MSS) beyond the horizon of the first generation, using technologies of the 1990's and to assist MSAT-X in directing its efforts, a conceptual design has been performed for a second-generation system to be launched around the mid-1990's. The design goal is to maximize the number of satellite channels and/or minimize the overall life-cycle cost, subject to the constraint of utilizing a commercial satellite bus with minimum modifications. To provide an optimal design, a series of trade-offs are performed, including antenna sizing, feed configurations, and interference analysis. Interference is a serious problem for MSAT and often an overlapping feed design is required to reduce interbeam interference. The trade-off studies will show that a simple non-overlapping feed is sufficient for the second-generation system, thus avoiding the need for the complicated beam-forming network that is associated with the overlapping feed designs. In addition, a system that operates at L-band, an alternative frequency band that is being considered by some for possible MSAT applications, is also presented.

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

    Science.gov (United States)

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

    1995-01-01

    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.

  2. Proactive TCP mechanism to improve Handover performance in Mobile Satellite and Terrestrial Networks

    CERN Document Server

    Vinayakray-Jani, Preetida

    2012-01-01

    Emerging standardization of Geo Mobile Radio (GMR-1) for satellite system is having strong resemblance to terrestrial GSM (Global System for Mobile communications) at the upper protocol layers and TCP (Transmission Control Protocol) is one of them. This space segment technology as well as terrestrial technology, is characterized by periodic variations in communication properties and coverage causing the termination of ongoing call as connections of Mobile Nodes (MN) alter stochastically. Although provisions are made to provide efficient communication infrastructure this hybrid space and terrestrial networks must ensure the end-to-end network performance so that MN can move seamlessly among these networks. However from connectivity point of view current TCP performance has not been engineered for mobility events in multi-radio MN. Traditionally, TCP has applied a set of congestion control algorithms (slow-start, congestion avoidance, fast retransmit, fast recovery) to probe the currently available bandwidth on...

  3. Fade-durations derived from land-mobile-satellite measurements in Australia

    Science.gov (United States)

    Hase, Yoshihiro; Vogel, Wolfhard J.; Goldhirsh, Julius

    1991-01-01

    Transmissions from the Japanese ETS-V geostationary satellite were measured at L band (1.5 GHz) in a vehicle driving on roads of southeastern Australia. The measurements were part of a program designed to characterize propagation effects due to roadside trees and terrain for mobile satellite service. It is shown that the cumulative distributions of fade and nonfade durations follow a lognormal and power law, respectively. At 1 percent probability, fades last 2-8 m, and nonfades 10-100 m, depending on the degree of shadowing. Phase fluctuations are generally small, allowing the channel characteristics to be estimated from levels only.

  4. Spectrum and orbit conservation as a factor in future mobile satellite system design

    Science.gov (United States)

    Bowen, Robert R.

    1990-01-01

    Access to the radio spectrum and geostationary orbit is essential to current and future mobile satellite systems. This access is difficult to obtain for current systems, and may be even more so for larger future systems. In this environment, satellite systems that minimize the amount of spectrum orbit resource required to meet a specific traffic requirement are essential. Several spectrum conservation techniques are discussed, some of which are complementary to designing the system at minimum cost. All may need to be implemented to the limits of technological feasibility if network growth is not to be constrained because of the lack of available spectrum-orbit resource.

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

    Science.gov (United States)

    Snowball, A. E.

    1986-06-01

    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.

  6. Recovery Act: Advanced Direct Methanol Fuel Cell for Mobile Computing

    Energy Technology Data Exchange (ETDEWEB)

    Fletcher, James H. [University of North Florida; Cox, Philip [University of North Florida; Harrington, William J [University of North Florida; Campbell, Joseph L [University of North Florida

    2013-09-03

    ABSTRACT Project Title: Recovery Act: Advanced Direct Methanol Fuel Cell for Mobile Computing PROJECT OBJECTIVE The objective of the project was to advance portable fuel cell system technology towards the commercial targets of power density, energy density and lifetime. These targets were laid out in the DOE’s R&D roadmap to develop an advanced direct methanol fuel cell power supply that meets commercial entry requirements. Such a power supply will enable mobile computers to operate non-stop, unplugged from the wall power outlet, by using the high energy density of methanol fuel contained in a replaceable fuel cartridge. Specifically this project focused on balance-of-plant component integration and miniaturization, as well as extensive component, subassembly and integrated system durability and validation testing. This design has resulted in a pre-production power supply design and a prototype that meet the rigorous demands of consumer electronic applications. PROJECT TASKS The proposed work plan was designed to meet the project objectives, which corresponded directly with the objectives outlined in the Funding Opportunity Announcement: To engineer the fuel cell balance-of-plant and packaging to meet the needs of consumer electronic systems, specifically at power levels required for mobile computing. UNF used existing balance-of-plant component technologies developed under its current US Army CERDEC project, as well as a previous DOE project completed by PolyFuel, to further refine them to both miniaturize and integrate their functionality to increase the system power density and energy density. Benefits of UNF’s novel passive water recycling MEA (membrane electrode assembly) and the simplified system architecture it enabled formed the foundation of the design approach. The package design was hardened to address orientation independence, shock, vibration, and environmental requirements. Fuel cartridge and fuel subsystems were improved to ensure effective fuel

  7. Recovery Act: Advanced Direct Methanol Fuel Cell for Mobile Computing

    Energy Technology Data Exchange (ETDEWEB)

    Fletcher, James H. [University of North Florida; Cox, Philip [University of North Florida; Harrington, William J [University of North Florida; Campbell, Joseph L [University of North Florida

    2013-09-03

    ABSTRACT Project Title: Recovery Act: Advanced Direct Methanol Fuel Cell for Mobile Computing PROJECT OBJECTIVE The objective of the project was to advance portable fuel cell system technology towards the commercial targets of power density, energy density and lifetime. These targets were laid out in the DOE’s R&D roadmap to develop an advanced direct methanol fuel cell power supply that meets commercial entry requirements. Such a power supply will enable mobile computers to operate non-stop, unplugged from the wall power outlet, by using the high energy density of methanol fuel contained in a replaceable fuel cartridge. Specifically this project focused on balance-of-plant component integration and miniaturization, as well as extensive component, subassembly and integrated system durability and validation testing. This design has resulted in a pre-production power supply design and a prototype that meet the rigorous demands of consumer electronic applications. PROJECT TASKS The proposed work plan was designed to meet the project objectives, which corresponded directly with the objectives outlined in the Funding Opportunity Announcement: To engineer the fuel cell balance-of-plant and packaging to meet the needs of consumer electronic systems, specifically at power levels required for mobile computing. UNF used existing balance-of-plant component technologies developed under its current US Army CERDEC project, as well as a previous DOE project completed by PolyFuel, to further refine them to both miniaturize and integrate their functionality to increase the system power density and energy density. Benefits of UNF’s novel passive water recycling MEA (membrane electrode assembly) and the simplified system architecture it enabled formed the foundation of the design approach. The package design was hardened to address orientation independence, shock, vibration, and environmental requirements. Fuel cartridge and fuel subsystems were improved to ensure effective fuel

  8. Communication satellite technology trends

    Science.gov (United States)

    Cuccia, Louis

    1986-01-01

    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.

  9. Direct broadcast satellite-radio: Portable and mobile reception trade-offs

    Science.gov (United States)

    Golshan, Nasser

    1991-09-01

    There has been considerable international effort in the areas of system studies, system development, and regulatory work for a Direct Broadcast Satellite Radio (DBS-R). An important milestone will be the 1992 World Radio Administrative Conference (WARC 1992) consideration of frequency allocation in the 500 - 3000 MHz range for such a service. There is an interagency agreement between Voice of America and the National Aeronautics and Space Administration for a coordinated program in DBS-R. This program includes seven tasks: systems tradeoff studies, propagation measurements, satellite experiment and demonstration, receiver development, market studies, regulatory studies, and WARC preparations. The findings of ongoing work under the first task, systems tradeoff studies, are discussed. Topics covered include digital bit rate and audio quality, propagation considerations and link margin estimates for portable reception, link margin estimates for mobile reception, coverage, and satellite size and cost estimates for a regional DBS-R coverage example.

  10. The ACTS Flight System - Cost-Effective Advanced Communications Technology. [Advanced Communication Technology Satellite

    Science.gov (United States)

    Holmes, W. M., Jr.; Beck, G. A.

    1984-01-01

    The multibeam communications package (MCP) for the Advanced Communications Technology Satellite (ACTS) to be STS-launched by NASA in 1988 for experimental demonstration of satellite-switched TDMA (at 220 Mbit/sec) and baseband-processor signal routing (at 110 or 27.5 Mbit/sec) is characterized. The developmental history of the ACTS, the program definition, and the spacecraft-bus and MCP parameters are reviewed and illustrated with drawings, block diagrams, and maps of the coverage plan. Advanced features of the MPC include 4.5-dB-noise-figure 30-GHz FET amplifiers and 20-GHz TWTA transmitters which provide either 40-W or 8-W RF output, depending on rain conditions. The technologies being tested in ACTS can give frequency-reuse factors as high as 20, thus greatly expanding the orbit/spectrum resources available for U.S. communications use.

  11. Use of negotiated rulemaking in developing technical rules for low-Earth orbit mobile satellite systems

    Science.gov (United States)

    Taylor, Leslie A.

    Technical innovations have converged with the exploding market demand for mobile telecommunications to create the impetus for low-earth orbit (LEO) communications satellite systems. The so-called 'Little LEO's' propose use of VHF and UHF spectrum to provide position - location and data messaging services. The so-called 'Big LEO's' propose to utilize the RDSS bands to provide voice and data services. In the United States, several applications were filed with the U.S. Federal Communications Commission (FCC) to construct and operate these mobile satellite systems. To enable the prompt introduction of such new technology services, the FCC is using innovative approaches to process the applications. Traditionally, when the FCC is faced with 'mutually exclusive' applications, e.g. a grant of one would preclude a grant of the others, it uses selection mechanisms such as comparative hearings or lotteries. In the case of the LEO systems, the FCC has sought to avoid these time-consuming approaches by using negotiated rulemakings. The FCC's objective is to enable the multiple applicants and other interested parties to agree on technical and service rules which will enable the grant of all qualified applications. With regard to the VHF/UHF systems, the Advisory Committee submitted a consensus report to the FCC. The process for the systems operating in the bands above 1 GHz involved more parties and more issues but still provided the FCC useful technical information to guide the adoption of rules for the new mobile satellite service.

  12. Multiple trellis coded modulation (MTCM) performance on a fading mobile satellite channel

    Science.gov (United States)

    Simon, Marvin K.; Divsalar, Dariush

    1987-01-01

    The author recently introduced the notion of multiple trellis coding, in which more than one channel symbol per trellis branch is transmitted. He showed that on the ideal additive white Gaussian noise (AWGN) channel, the combination of multiple trellis coding with M-ary modulation yields a performance gain with symmetric signal sets comparable to and in some cases better than that previously achieved only with signal constellation asymmetry. The combination of conventional trellis coding with multiple phase-shift-keyed (MPSK) signaling has recently been shown by the author to be a well-suited modulation/coding scheme for transmission over the fading mobile satellite channel. In particular, a rate 2/3 coded 8-PSK scheme operating at 4800 b/s is currently under development for use in NASA's Mobile Satellite Experiment (MSAT-X). The author applies the multiple trellis-coded modulation technique in the same fading mobile satellite environment, extending the analysis results previously found for its performance over the AWGN channel to the MSAT-X channel.

  13. Land mobile satellite communication system. Volume 2: Traffic analysis and market demand for the land mobile communications system in the European scenario

    Science.gov (United States)

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

    1986-06-01

    The socioeconomic desirability in terms of market demand, technical economic feasibility, and price-performance for a Land Mobile Communication system ground based and/or satellite aided, able to satisfy the request of the traffic demand, foreseable in the 1995-2005 time frame, for the Western European countries was assessed. The criterion of economic value of the mobile system is considered as the driving element. The presence of gaps in the terrestrial system and reasonable traffic extrapolations suggest a very attractive role for a land mobile satellite communications mission.

  14. [Mobile hospital -real time mobile telehealthcare system with ultrasound and CT van using high-speed satellite communication-].

    Science.gov (United States)

    Takizawa, Masaomi; Miyashita, Toyohisa; Murase, Sumio; Kanda, Hirohito; Karaki, Yoshiaki; Yagi, Kazuo; Ohue, Toru

    2003-01-01

    A real-time telescreening system is developed to detect early diseases for rural area residents using two types of mobile vans with a portable satellite station. The system consists of a satellite communication system with 1.5Mbps of the JCSAT-1B satellite, a spiral CT van, an ultrasound imaging van with two video conference system, a DICOM server and a multicast communication unit. The video image and examination image data are transmitted from the van to hospitals and the university simultaneously. Physician in the hospital observes and interprets exam images from the van and watches the video images of the position of ultrasound transducer on screenee in the van. After the observation images, physician explains a results of the examination by the video conference system. Seventy lung CT screening and 203 ultrasound screening were done from March to June 2002. The trial of this real time screening suggested that rural residents are given better healthcare without visit to the hospital. And it will open the gateway to reduce the medical cost and medical divide between city area and rural area.

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

    Science.gov (United States)

    Naderi, F. (Editor)

    1982-01-01

    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.

  16. An efficient and secure anonymous authentication scheme for mobile satellite communication systems

    Directory of Open Access Journals (Sweden)

    Yoo Kee-Young

    2011-01-01

    Full Text Available Abstract This paper proposes a new efficient and secure anonymous authentication scheme for mobile satellite communication systems. Compared with the related schemes, the proposed scheme achieves the following three main advantages: (1 It is just based on a secure one-way hash function for avoiding complex computations for both mobile users and network control center (NCC, (2 it does not require sensitive verification table which may cause NCC to become an attractive target for numerous attacks (e.g., insertion attacks and stolen-verifier attacks, and (3 it provides higher security level (e.g., secure mutual authentication and key establishment, confidential communication, user's privacy, simple key management, and session key independence. As a result, the proposed scheme is very suitable for lightweight-device environments because of very low computation overload on the part of both mobile user and NCC.

  17. Fade measurements at L-band and UHF in mountainous terrain for land mobile satellite systems

    Science.gov (United States)

    Vogel, Wolfhard J.; Goldhirsh, Julius

    1988-01-01

    Fading results related to land mobile satellite communications at L-band (1502 MHz) and UHF (870 MHz) are described. These results were derived from an experiment performed in a series of canyon passes in the Boulder, Colorado region of the US. The experimental configuration involved a helicopter as the source platform, which maintained a relatively fixed geometry with a mobile van containing the receiver and data-acquisition system. An unobstructed line of sight between the radiating sources and the receiving van was, for the most part, also maintained. In this configuration, the dominant mechanism causing signal fading (or enhancement) is a result of multipath. The resulting fade distributions demonstrated that at the 1 percent and 5 percent levels, 5.5- and 2.6-dB fades were on the average exceeded at L-band and 4.8- and 2.4-dB at UHF, respectively, for a path elevation angle of 45 deg. The canyon results as compared with previous roadside-tree-shadowing results demonstrate that the deciding factor dictating fade margin for future land mobile satellite systems is tree shadowing rather than fades caused by multipath.

  18. Remote, mobile telemedicine: the satellite transmission of medical data from Mount Logan.

    Science.gov (United States)

    Otto, C; Pipe, A

    1997-01-01

    The purpose of this investigation was to demonstrate the potential of remote, mobile telemedicine during a four-week, high-altitude mountaineering expedition to Mount Logan, Canada's highest summit. Using a mobile satellite terminal and a laptop computer (both powered by a photovoltaic solar panel), ECG tracings and blood pressure measurements, in addition to colour images, short-segment video and audio clips were transmitted during the course of the ascent. The data were transmitted via a mobile communications satellite to a ground station in Ottawa, a distance of over 4000 km. The data were then transferred to the public switched data network and delivered to the University of Ottawa Heart Institute for analysis. Similarly, data were transmitted from the ground station to the expedition team on Mount Logan throughout the ascent. Using this technique, medical diagnosis and emergency care can be facilitated in extreme and isolated locations lacking a telecommunications infrastructure. Such technology has applications in developing countries, disaster response efforts, remote civilian and military operations, and in space operations.

  19. R&D of a Next Generation LEO System for Global Multimedia Mobile Satellite Communications

    Science.gov (United States)

    Morikawa, E.; Motoyoshi, S.; Koyama, Y.; Suzuki, R.; Yasuda, Y.

    2002-01-01

    Next-generation LEO System Research Center (NeLS) was formed in the end of 1997 as a research group under the Telecommunications Advancement Organization of Japan, in cooperation with the telecommunications operators, manufacturers, universities and governmental research organization. The aim of this project is to develop new technology for global multimedia mobile satellite communications services with a user data rate around 2Mbps for handy terminals. component of the IMT-2000, and the second generation of the big-LEO systems. In prosecuting this project, two-phase approach, phase 1 and phase 2, is considered. Phase 1 is the system definition and development of key technologies. In Phase 2, we plan to verify the developed technology in Phase 1 on space. From this year we shifted the stage to Phase 2, and are now developing the prototype of on-board communication systems for flight tests, which will be planed at around 2006. The satellite altitude is assumed to be 1200 km in order to reduce the number of satellites, to avoid the Van Allen radiation belts and to increase the minimum elevation angle. Ten of the circular orbits with 55 degree of inclination are selected to cover the earth surface from -70 to 70 degree in latitude. 12 satellites are positioned at regular intervals in each orbit. In this case, the minimum elevation angle from the user terminal can be keep more than 20 degree for the visibility of the satellite, and 15 degree for simultaneous visibility of two satellites. Then, NeLS Research Center was focusing on the development of key technologies as the phase 1 project. Four kinds of key technologies; DBF satellite antenna, optical inter-satellite link system, satellite network technology with on-board ATM switch and variable rate modulation were selected. Satellite Antenna Technology: Development of on-board direct radiating active phased array antenna with digital beam forming technology would be one of the most important breakthroughs for the

  20. Economic and market aspects of land mobile satellite compared to terrestrial cellular radio

    Science.gov (United States)

    1986-09-01

    Cellular radio and INMARSAT Standard-C technologies for thin route mobile communications in the immediate future are compared. It is suggested that while the cellular radio systems are in operation or are planned for introduction in the immediate future in most Western European nations, coverage gaps are likely to persist due to economic, technical, and institutional reasons. A satellite system, with its inherent qualities, can fill the gap by providing a thin-route coverage in Europe, Middle East, and Africa. However, when subscriber densities increase to the point that cellular radio service becomes feasible in previously uneconomical regions, satellite service becomes less attractive, and may be eventually displaced. Where only alphanumeric two-way messaging is required, INMARSAT Standard-C can provide thin route data messaging service to users with wide-area, long-distance, or transborder communications requirements.

  1. Concepts and cost trade-offs for land vehicle antennas in satellite mobile communications

    Science.gov (United States)

    Haddad, H. A.

    1948-01-01

    Several antenna design concepts, operating at UHF (821 to 825 MHz transmit and 866 to 870 MHz receive bands), with gain ranging between 6 and 12 dBic, that are suitable for land mobile vehicles are presented. The antennas may be used within CONUS and ALASKA to communicate to and from a geosynchronous satellite. Depending on the type of steering mechanism, the antennas are broken down into three categories; (1) electronically scanned arrays with phase shifters, (2) electronically switched arrays with switchable power dividers/combiners, and (3) mechanically steered arrays. The operating characteristics of two of these design concepts, one a conformal antenna with electronic beam steering and the other a nonconformal design with mechanical steering, were evaluated with regard to two and three satellite system. Cost estimates of various antenna concepts were made and plotted against their overall gain performance.

  2. Trellis coding with Continuous Phase Modulation (CPM) for satellite-based land-mobile communications

    Science.gov (United States)

    1989-01-01

    This volume of the final report summarizes the results of our studies on the satellite-based mobile communications project. It includes: a detailed analysis, design, and simulations of trellis coded, full/partial response CPM signals with/without interleaving over various Rician fading channels; analysis and simulation of computational cutoff rates for coherent, noncoherent, and differential detection of CPM signals; optimization of the complete transmission system; analysis and simulation of power spectrum of the CPM signals; design and development of a class of Doppler frequency shift estimators; design and development of a symbol timing recovery circuit; and breadboard implementation of the transmission system. Studies prove the suitability of the CPM system for mobile communications.

  3. A Mobile Communications Space Link Between the Space Shuttle Orbiter and the Advanced Communications Technology Satellite

    Science.gov (United States)

    Fink, Patrick; Arndt, G. D.; Bondyopadhyay, P.; Shaw, Roland

    1994-01-01

    A communications experiment is described as a link between the Space Shuttle Orbiter (SSO) and the Advanced Communications Technology Satellite (ACTS). Breadboarding for this experiment has led to two items with potential for commercial application: a 1-Watt Ka-band amplifier and a Ka-band, circularly polarized microstrip antenna. Results of the hybrid Ka-band amplifier show gain at 30 dB and a saturated output power of 28.5 dBm. A second version comprised of MMIC amplifiers is discussed. Test results of the microstrip antenna subarray show a gain of approximately 13 dB and excellent circular polarization.

  4. ACTS (Advanced Communications Technology Satellite) Propagation Experiment: Preprocessing Software User's Manual

    Science.gov (United States)

    Crane, Robert K.; Wang, Xuhe; Westenhaver, David

    1996-01-01

    The preprocessing software manual describes the Actspp program originally developed to observe and diagnose Advanced Communications Technology Satellite (ACTS) propagation terminal/receiver problems. However, it has been quite useful for automating the preprocessing functions needed to convert the terminal output to useful attenuation estimates. Prior to having data acceptable for archival functions, the individual receiver system must be calibrated and the power level shifts caused by ranging tone modulation must be received. Actspp provides three output files: the daylog, the diurnal coefficient file, and the file that contains calibration information.

  5. Effects of fade distribution on a mobile satellite downlink and uplink performance in a frequency reuse cellular configuration

    Science.gov (United States)

    Boutin, Karl; Lecours, Michel; Pelletier, Marcel; Delisle, Gilles Y.

    1990-01-01

    In a mobile satellite system with a frequency reuse cellular configuration, significant co-channel interference can be experienced due to the antenna sidelobe level. The signal will be subjected not only to its own fading, but also to the effect of the varying degree of fading on co-channel interferer, and this interference will behave differently in the up and in the down link. This paper presents a quantitative evaluation of the combined effects of fades and co-channel interference on a mobile satellite link.

  6. System capacity and economic modeling computer tool for satellite mobile communications systems

    Science.gov (United States)

    Wiedeman, Robert A.; Wen, Doong; Mccracken, Albert G.

    1988-01-01

    A unique computer modeling tool that combines an engineering tool with a financial analysis program is described. The resulting combination yields a flexible economic model that can predict the cost effectiveness of various mobile systems. Cost modeling is necessary in order to ascertain if a given system with a finite satellite resource is capable of supporting itself financially and to determine what services can be supported. Personal computer techniques using Lotus 123 are used for the model in order to provide as universal an application as possible such that the model can be used and modified to fit many situations and conditions. The output of the engineering portion of the model consists of a channel capacity analysis and link calculations for several qualities of service using up to 16 types of earth terminal configurations. The outputs of the financial model are a revenue analysis, an income statement, and a cost model validation section.

  7. The design and networking of dynamic satellite constellations for global mobile communication systems

    Science.gov (United States)

    Cullen, Cionaith J.; Benedicto, Xavier; Tafazolli, Rahim; Evans, Barry

    1993-01-01

    Various design factors for mobile satellite systems, whose aim is to provide worldwide voice and data communications to users with hand-held terminals, are examined. Two network segments are identified - the ground segment (GS) and the space segment (SS) - and are seen to be highly dependent on each other. The overall architecture must therefore be adapted to both of these segments, rather than each being optimized according to its own criteria. Terrestrial networks are grouped and called the terrestrial segment (TS). In the SS, of fundamental importance is the constellation altitude. The effect of the altitude on decisions such as constellation design choice and on network aspects like call handover statistics are fundamental. Orbit resonance is introduced and referred to throughout. It is specifically examined for its useful properties relating to GS/SS connectivities.

  8. Planning of mobility and parking. The acting of the Urban Mobility Plan

    Directory of Open Access Journals (Sweden)

    Giuseppe Mazzeo

    2009-05-01

    Full Text Available In the urban areas the mobility system is strategic for its working and it is composed of a series of territorial closely interrelated elements. Among these the parking is one of the most important and its organization is a key point of an appropriate planning of mobility: this importance is mainly due to its character of attractor of vehicular flows. The structure of large and medium sized Italian cities imposes many constraints to the creation and the use of parking areas for their impact on the urban livability; the problem is the organization of the whole city, the correct location of the areas and the opportunity to regulate the access to certain areas: in fact the programming of parking areas can have strong repercussions on the city. Another element can be considered: the choice to build parking areas in the center of the towns is in logical conflict with the traffic limiting policies, because the infrastructure, if built, can be used and the investment must be repaid; on the other hand, the decision that some sensitive areas should not be affected by parking infrastructure produces the necessity to strengthen other public services: the question is not only physical (space availability, but it is related with the distribution of opportunities and equipments, so if the center is better served by public transport, the periphery must be served by other infrastructures. As said, the choice of sites for parking’s location and the determination of their operating characteristics can have strong impacts on the organization and the livability of the city itself; it follows the necessity of a close connection with the urban planning and an attention to the morphological characters of the different parts of the city. The tools for planning the mobility and, within it, the parking system, are several. The Urban Mobility Plan is the newest among them; it is a strategic tool because its effects are gathered on the system as a whole and it assumes an

  9. Efficient Wideband Spectrum Sensing with Maximal Spectral Efficiency for LEO Mobile Satellite Systems

    Directory of Open Access Journals (Sweden)

    Feilong Li

    2017-01-01

    Full Text Available The usable satellite spectrum is becoming scarce due to static spectrum allocation policies. Cognitive radio approaches have already demonstrated their potential towards spectral efficiency for providing more spectrum access opportunities to secondary user (SU with sufficient protection to licensed primary user (PU. Hence, recent scientific literature has been focused on the tradeoff between spectrum reuse and PU protection within narrowband spectrum sensing (SS in terrestrial wireless sensing networks. However, those narrowband SS techniques investigated in the context of terrestrial CR may not be applicable for detecting wideband satellite signals. In this paper, we mainly investigate the problem of joint designing sensing time and hard fusion scheme to maximize SU spectral efficiency in the scenario of low earth orbit (LEO mobile satellite services based on wideband spectrum sensing. Compressed detection model is established to prove that there indeed exists one optimal sensing time achieving maximal spectral efficiency. Moreover, we propose novel wideband cooperative spectrum sensing (CSS framework where each SU reporting duration can be utilized for its following SU sensing. The sensing performance benefits from the novel CSS framework because the equivalent sensing time is extended by making full use of reporting slot. Furthermore, in respect of time-varying channel, the spatiotemporal CSS (ST-CSS is presented to attain space and time diversity gain simultaneously under hard decision fusion rule. Computer simulations show that the optimal sensing settings algorithm of joint optimization of sensing time, hard fusion rule and scheduling strategy achieves significant improvement in spectral efficiency. Additionally, the novel ST-CSS scheme performs much higher spectral efficiency than that of general CSS framework.

  10. Efficient Wideband Spectrum Sensing with Maximal Spectral Efficiency for LEO Mobile Satellite Systems

    Science.gov (United States)

    Li, Feilong; Li, Zhiqiang; Li, Guangxia; Dong, Feihong; Zhang, Wei

    2017-01-01

    The usable satellite spectrum is becoming scarce due to static spectrum allocation policies. Cognitive radio approaches have already demonstrated their potential towards spectral efficiency for providing more spectrum access opportunities to secondary user (SU) with sufficient protection to licensed primary user (PU). Hence, recent scientific literature has been focused on the tradeoff between spectrum reuse and PU protection within narrowband spectrum sensing (SS) in terrestrial wireless sensing networks. However, those narrowband SS techniques investigated in the context of terrestrial CR may not be applicable for detecting wideband satellite signals. In this paper, we mainly investigate the problem of joint designing sensing time and hard fusion scheme to maximize SU spectral efficiency in the scenario of low earth orbit (LEO) mobile satellite services based on wideband spectrum sensing. Compressed detection model is established to prove that there indeed exists one optimal sensing time achieving maximal spectral efficiency. Moreover, we propose novel wideband cooperative spectrum sensing (CSS) framework where each SU reporting duration can be utilized for its following SU sensing. The sensing performance benefits from the novel CSS framework because the equivalent sensing time is extended by making full use of reporting slot. Furthermore, in respect of time-varying channel, the spatiotemporal CSS (ST-CSS) is presented to attain space and time diversity gain simultaneously under hard decision fusion rule. Computer simulations show that the optimal sensing settings algorithm of joint optimization of sensing time, hard fusion rule and scheduling strategy achieves significant improvement in spectral efficiency. Additionally, the novel ST-CSS scheme performs much higher spectral efficiency than that of general CSS framework. PMID:28117712

  11. Efficient Wideband Spectrum Sensing with Maximal Spectral Efficiency for LEO Mobile Satellite Systems.

    Science.gov (United States)

    Li, Feilong; Li, Zhiqiang; Li, Guangxia; Dong, Feihong; Zhang, Wei

    2017-01-21

    The usable satellite spectrum is becoming scarce due to static spectrum allocation policies. Cognitive radio approaches have already demonstrated their potential towards spectral efficiency for providing more spectrum access opportunities to secondary user (SU) with sufficient protection to licensed primary user (PU). Hence, recent scientific literature has been focused on the tradeoff between spectrum reuse and PU protection within narrowband spectrum sensing (SS) in terrestrial wireless sensing networks. However, those narrowband SS techniques investigated in the context of terrestrial CR may not be applicable for detecting wideband satellite signals. In this paper, we mainly investigate the problem of joint designing sensing time and hard fusion scheme to maximize SU spectral efficiency in the scenario of low earth orbit (LEO) mobile satellite services based on wideband spectrum sensing. Compressed detection model is established to prove that there indeed exists one optimal sensing time achieving maximal spectral efficiency. Moreover, we propose novel wideband cooperative spectrum sensing (CSS) framework where each SU reporting duration can be utilized for its following SU sensing. The sensing performance benefits from the novel CSS framework because the equivalent sensing time is extended by making full use of reporting slot. Furthermore, in respect of time-varying channel, the spatiotemporal CSS (ST-CSS) is presented to attain space and time diversity gain simultaneously under hard decision fusion rule. Computer simulations show that the optimal sensing settings algorithm of joint optimization of sensing time, hard fusion rule and scheduling strategy achieves significant improvement in spectral efficiency. Additionally, the novel ST-CSS scheme performs much higher spectral efficiency than that of general CSS framework.

  12. 47 CFR 25.142 - Licensing provisions for the non-voice, non-geostationary mobile-satellite service.

    Science.gov (United States)

    2010-10-01

    ... more than thirty minutes and the cause(s) of such outages; (2) A detailed description of the... information publicly available at the Commission at the time of filing, that they will not cause unacceptable... operate. (2) Applicants for a non-voice, non-geostationary mobile-satellite must identify the power...

  13. Low gain and steerable vehicle antennas for communications with land mobile satellite

    Science.gov (United States)

    Woo, K.

    1982-01-01

    Current development activities at JPL for ground mobile vehicle antennas to be used with the Land Mobile Satellite Service (LMSS) system are described. Both low gain and electronically steerable high gain type antennas are discussed in terms of their design concept and RF performance. For the low gain type, three classes of antennas are under various stages of development. These are the crossed-drooping dipole, quadrifilar helix, and microstrip patch designs. The antennas are intended to provide circularly-polarized radiation with a minimum of 3-dB gain in the angular region from 19 degrees to 60 deg from the horizon in elevation plane and with an omnidirectional pattern in azimuthal plane. For the electronically steerable high gain type, circularly-polarized microstrip patch phased arrays formed on a planar surface and on the surface of a truncated cone are under study. The arrays are intended to provide a minimum of 12 dB gain in the same angular region in elevation plane at all azimuthal angles. This coverage is accomplished by scanning the high gain pencil beam in both elevation and azimuthal directions. Both types of antennas are to transmit at 821-831 MHz band and to receive at 866-876 MHz band. They must be of low cost design and reasonably conformal to the vehicle.

  14. A FD/DAMA network architecture for the first generation land mobile satellite services

    Science.gov (United States)

    Yan, T.-Y.; Wang, C.; Cheng, U.; Dessouky, K.; Rafferty, W.

    1989-01-01

    A frequency division/demand assigned multiple access (FD/DAMA) network architecture for the first-generation land mobile satellite services is presented. Rationales and technical approaches are described. In this architecture, each mobile subscriber must follow a channel access protocol to make a service request to the network management center before transmission for either open-end or closed-end services. Open-end service requests will be processed on a blocked call cleared basis, while closed-end requests will be processed on a first-come-first-served basis. Two channel access protocols are investigated, namely, a recently proposed multiple channel collision resolution scheme which provides a significantly higher useful throughput, and the traditional slotted Aloha scheme. The number of channels allocated for either open-end or closed-end services can be adaptively changed according to aggregated traffic requests. Both theoretical and simulation results are presented. Theoretical results have been verified by simulation on the JPL network testbed.

  15. APPLICATION OF VISION METROLOGY TO IN-ORBIT MEASUREMENT OF LARGE REFLECTOR ONBOARD COMMUNICATION SATELLITE FOR NEXT GENERATION MOBILE SATELLITE COMMUNICATION

    Directory of Open Access Journals (Sweden)

    M. Akioka

    2016-06-01

    Full Text Available Satellite for next generation mobile satellite communication service with small personal terminal requires onboard antenna with very large aperture reflector larger than twenty meters diameter because small personal terminal with lower power consumption in ground base requires the large onboard reflector with high antenna gain. But, large deployable antenna will deform in orbit because the antenna is not a solid dish but the flexible structure with fine cable and mesh supported by truss. Deformation of reflector shape deteriorate the antenna performance and quality and stability of communication service. However, in case of digital beam forming antenna with phased array can modify the antenna beam performance due to adjustment of excitation amplitude and excitation phase. If we can measure the reflector shape precisely in orbit, beam pattern and antenna performance can be compensated with the updated excitation amplitude and excitation phase parameters optimized for the reflector shape measured every moment. Softbank Corporation and National Institute of Information and Communications Technology has started the project "R&D on dynamic beam control technique for next generation mobile communication satellite" as a contracted research project sponsored by Ministry of Internal Affairs and Communication of Japan. In this topic, one of the problem in vision metrology application is a strong constraints on geometry for camera arrangement on satellite bus with very limited space. On satellite in orbit, we cannot take many images from many different directions as ordinary vision metrology measurement and the available area for camera positioning is quite limited. Feasibility of vision metrology application and general methodology to apply to future mobile satellite communication satellite is to be found. Our approach is as follows: 1 Development of prototyping simulator to evaluate the expected precision for network design in zero order and first order

  16. Application of Vision Metrology to In-Orbit Measurement of Large Reflector Onboard Communication Satellite for Next Generation Mobile Satellite Communication

    Science.gov (United States)

    Akioka, M.; Orikasa, T.; Satoh, M.; Miura, A.; Tsuji, H.; Toyoshima, M.; Fujino, Y.

    2016-06-01

    Satellite for next generation mobile satellite communication service with small personal terminal requires onboard antenna with very large aperture reflector larger than twenty meters diameter because small personal terminal with lower power consumption in ground base requires the large onboard reflector with high antenna gain. But, large deployable antenna will deform in orbit because the antenna is not a solid dish but the flexible structure with fine cable and mesh supported by truss. Deformation of reflector shape deteriorate the antenna performance and quality and stability of communication service. However, in case of digital beam forming antenna with phased array can modify the antenna beam performance due to adjustment of excitation amplitude and excitation phase. If we can measure the reflector shape precisely in orbit, beam pattern and antenna performance can be compensated with the updated excitation amplitude and excitation phase parameters optimized for the reflector shape measured every moment. Softbank Corporation and National Institute of Information and Communications Technology has started the project "R&D on dynamic beam control technique for next generation mobile communication satellite" as a contracted research project sponsored by Ministry of Internal Affairs and Communication of Japan. In this topic, one of the problem in vision metrology application is a strong constraints on geometry for camera arrangement on satellite bus with very limited space. On satellite in orbit, we cannot take many images from many different directions as ordinary vision metrology measurement and the available area for camera positioning is quite limited. Feasibility of vision metrology application and general methodology to apply to future mobile satellite communication satellite is to be found. Our approach is as follows: 1) Development of prototyping simulator to evaluate the expected precision for network design in zero order and first order 2) Trial

  17. Advanced Communication Technology Satellite (ACTS) Multibeam Antenna On-Orbit Performance

    Science.gov (United States)

    1995-01-01

    The NASA Lewis Research Center's Advanced Communication Technology Satellite (ACTS) was launched in September 1993. ACTS introduced several new technologies, including a multibeam antenna (MBA) operating at extremely short wavelengths never before used in communications. This antenna, which has both fixed and rapidly reconfigurable high-energy spot beams (150 miles in diameter), serves users equipped with small antenna terminals. Extensive structural and thermal analyses have been performed for simulating the ACTS MBA on-orbit performance. The results show that the reflector surfaces (mainly the front subreflector), antenna support assembly, and metallic surfaces on the spacecraft body will be distorted because of the thermal effects of varying solar heating, which degrade the ACTS MBA performance. Since ACTS was launched, a number of evaluations have been performed to assess MBA performance in the space environment. For example, the on-orbit performance measurements found systematic environmental disturbances to the MBA beam pointing. These disturbances were found to be imposed by the attitude control system, antenna and spacecraft mechanical alignments, and on-orbit thermal effects. As a result, the MBA may not always exactly cover the intended service area. In addition, the on-orbit measurements showed that antenna pointing accuracy is the performance parameter most sensitive to thermal distortions on the front subreflector surface and antenna support assemblies. Several compensation approaches were tested and evaluated to restore on-orbit pointing stability. A combination of autotrack (75 percent of the time) and Earth sensor control (25 percent of the time) was found to be the best way to compensate for antenna pointing error during orbit. This approach greatly minimizes the effects of thermal distortions on antenna beam pointing.

  18. A History of the Improvement of Internet Protocols Over Satellites Using ACTS

    Science.gov (United States)

    Allman, Mark; Kruse, Hans; Ostermann, Shawn

    2000-01-01

    This paper outlines the main results of a number of ACTS experiments on the efficacy of using standard Internet protocols over long-delay satellite channels. These experiments have been jointly conducted by NASAs Glenn Research Center and Ohio University over the last six years. The focus of our investigations has been the impact of long-delay networks with non-zero bit-error rates on the performance of the suite of Internet protocols. In particular, we have focused on the most widely used transport protocol, the Transmission Control Protocol (TCP), as well as several application layer protocols. This paper presents our main results, as well as references to more verbose discussions of our experiments.

  19. Advanced Communications Technology Satellite (ACTS) Fade Compensation Protocol Impact on Very Small-Aperture Terminal Bit Error Rate Performance

    Science.gov (United States)

    Cox, Christina B.; Coney, Thom A.

    1999-01-01

    The Advanced Communications Technology Satellite (ACTS) communications system operates at Ka band. ACTS uses an adaptive rain fade compensation protocol to reduce the impact of signal attenuation resulting from propagation effects. The purpose of this paper is to present the results of an analysis characterizing the improvement in VSAT performance provided by this protocol. The metric for performance is VSAT bit error rate (BER) availability. The acceptable availability defined by communication system design specifications is 99.5% for a BER of 5E-7 or better. VSAT BER availabilities with and without rain fade compensation are presented. A comparison shows the improvement in BER availability realized with rain fade compensation. Results are presented for an eight-month period and for 24 months spread over a three-year period. The two time periods represent two different configurations of the fade compensation protocol. Index Terms-Adaptive coding, attenuation, propagation, rain, satellite communication, satellites.

  20. Designing a better place for patients: professional struggles surrounding satellite and mobile dialysis units.

    Science.gov (United States)

    Lehoux, Pascale; Daudelin, Geneviève; Poland, Blake; Andrews, Gavin J; Holmes, Dave

    2007-10-01

    The professional claims and struggles involved in the design of non-traditional health care places are rarely problematized in applied health research, perhaps because they tend to fade away once the new design is implemented. This paper offers insights into such professional tensions and their impact on health care delivery by examining the design of two dialysis service delivery models in Quebec, Canada. The satellite units were hosted in two small hospitals and staffed by recently trained nurses. The mobile unit was a bus fitted to accommodate five dialysis stations. It was staffed by experienced nurses and travelled back and forth between a university teaching hospital and two sites. In both projects, nephrologists supervised from a distance via a videoconferencing system. In this paper, we draw mainly from interviews with managers (mostly nurses) and physicians (n=18), and from on-site observations. Nephrologists, medical internists, and managers all supported the goal of providing "closer-to-patient" services. However, they held varying opinions on how to best materialize this goal. By comparing two models involving different clinical and spatial logics, we underscore the ways in which the design of non-traditional health care places opens up space for the re-negotiation of clinical norms. Instead of relatively straightforward conflicts between professions, we observed subtle but inexorable tensions within and beyond professional groups, who sought to measure up to "ideal standards" while acknowledging the contingencies of health care places.

  1. A new coherent demodulation technique for land-mobile satellite communications

    Science.gov (United States)

    Yoshida, Shousei; Tomita, Hideho

    1990-01-01

    An advanced coherent demodulation technique is described for land mobile satellite (LMS) communications. The proposed technique features a combined narrow/wind band dual open loop carrier phase estimator, which is effectively able to compensate the fast carrier phase fluctuation by fading with sacrificing a phase slip rate. Also included is the realization of quick carrier and clock reacquisition after shadowing by taking open loop structure. Its bit error rate (BER) performance is superior to that of existing detection schemes, showing a BER of 1 x 10(exp -2) at 6.3 dB E sub b/N sub o over the Rician channel with 10 dB C/M and 200 Hz (1/16 modulation rate) fading pitch f sub d for QPSK. The proposed scheme consists of a fast response carrier recovery and a quick bit timing recovery with an interpolation. An experimental terminal model was developed to evaluate its performance at fading conditions. The results are quite satisfactory, giving prospects for future LMS applications.

  2. Compact, low profile antennas for MSAT and mini-M and Std-M land mobile satellite communications

    Science.gov (United States)

    Strickland, P. C.

    1995-01-01

    CAL Corporation has developed a new class of low profile radiating elements for use in planar phased array antennas. These new elements have been used in the design of a low cost, compact, low profile antenna unit for MSAT and INMARSAT Mini-M land mobile satellite communications. The antenna unit which measures roughly 32 cm in diameter by 5 cm deep incorporates a compact LNA and diplexer unit as well as a complete, low cost, beam steering system. CAL has also developed a low profile antenna unit for INMARSAT-M land mobile satellite communications. A number of these units, which utilize a microstrip patch array design, were put into service in 1994.

  3. LOOPUS Mob-D: System concept for a public mobile satellite system providing integrated digital services for the Northern Hemisphere from an elliptical orbit

    Science.gov (United States)

    Kuhlen, H.; Horn, P.

    1990-08-01

    A new concept for a satellite based public mobile communications system LOOPUS Mob-D is introduced where most of the 'classical' problems in mobile satellite systems are approached in a different way. The LOOPUS system will offer a total capacity of 6000 high rate channel in three service areas (Europe, Asia, and North America) covering the entire Northern Hemisphere with a set of group special mobile (GSM) compatible mobile services eventually providing the 'office in the car'. Special characteristics of the LOOPUS orbit and the communications network architecture are highlighted.

  4. All-digital multicarrier demodulators for on-board processing satellites in mobile communication systems

    Science.gov (United States)

    Yim, Wan Hung

    Economical operation of future satellite systems for mobile communications can only be fulfilled by using dedicated on-board processing satellites, which would allow both cheap earth terminals and lower space segment costs. With on-board modems and codecs, the up-link and down-link can be optimized separately. An attractive scheme is to use frequency-division multiple access/single chanel per carrier (FDMA/SCPC) on the up-link and time division multiplexing (TDM) on the down-link. This scheme allows mobile terminals to transmit a narrow band, low power signal, resulting in smaller dishes and high power amplifiers (HPA's) with lower output power. On the up-link, there are hundreds to thousands of FDM channels to be demodulated on-board. The most promising approach is the use of all-digital multicarrier demodulators (MCD's), where analog and digital hardware are efficiently shared among channels, and digital signal processing (DSP) is used at an early stage to take advantage of very large scale integration (VLSI) implementation. A MCD consists of a channellizer for separation of frequency division multiplexing (FDM) channels, followed by individual modulators for each channel. Major research areas in MCD's are in multirate DSP, and the optimal estimation for synchronization, which form the basis of the thesis. Complex signal theories are central to the development of structured approaches for the sampling and processing of bandpass signals, which are the foundations in both channellizer and demodulator design. In multirate DSP, polyphase theories replace many ad-hoc, tedious and error-prone design procedures. For example, a polyphase-matrix deep space network frequency and timing system (DFT) channellizer includes all efficient filter bank techniques as special cases. Also, a polyphase-lattice filter is derived, not only for sampling rate conversion, but also capable of sampling phase variation, which is required for symbol timing adjustment in all

  5. Using Social Media and Mobile Devices to Discover and Share Disaster Data Products Derived From Satellites

    Science.gov (United States)

    Mandl, Daniel; Cappelaere, Patrice; Frye, Stuart; Evans, John; Moe, Karen

    2014-01-01

    Data products derived from Earth observing satellites are difficult to find and share without specialized software and often times a highly paid and specialized staff. For our research effort, we endeavored to prototype a distributed architecture that depends on a standardized communication protocol and applications program interface (API) that makes it easy for anyone to discover and access disaster related data. Providers can easily supply the public with their disaster related products by building an adapter for our API. Users can use the API to browse and find products that relate to the disaster at hand, without a centralized catalogue, for example floods, and then are able to share that data via social media. Furthermore, a longerterm goal for this architecture is to enable other users who see the shared disaster product to be able to generate the same product for other areas of interest via simple point and click actions on the API on their mobile device. Furthermore, the user will be able to edit the data with on the ground local observations and return the updated information to the original repository of this information if configured for this function. This architecture leverages SensorWeb functionality [1] presented at previous IGARSS conferences. The architecture is divided into two pieces, the frontend, which is the GeoSocial API, and the backend, which is a standardized disaster node that knows how to talk to other disaster nodes, and also can communicate with the GeoSocial API. The GeoSocial API, along with the disaster node basic functionality enables crowdsourcing and thus can leverage insitu observations by people external to a group to perform tasks such as improving water reference maps, which are maps of existing water before floods. This can lower the cost of generating precision water maps. Keywords-Data Discovery, Disaster Decision Support, Disaster Management, Interoperability, CEOS WGISS Disaster Architecture

  6. Relasphone—Mobile and Participative In Situ Forest Biomass Measurements Supporting Satellite Image Mapping

    Directory of Open Access Journals (Sweden)

    Matthieu Molinier

    2016-10-01

    Full Text Available Due to the high cost of traditional forest plot measurements, the availability of up-to-date in situ forest inventory data has been a bottleneck for remote sensing image analysis in support of the important global forest biomass mapping. Capitalizing on the proliferation of smartphones, citizen science is a promising approach to increase spatial and temporal coverages of in situ forest observations in a cost-effective way. Digital cameras can be used as a relascope device to measure basal area, a forest density variable that is closely related to biomass. In this paper, we present the Relasphone mobile application with extensive accuracy assessment in two mixed forest sites from different biomes. Basal area measurements in Finland (boreal zone were in good agreement with reference forest inventory plot data on pine ( R 2 = 0 . 75 , R M S E = 5 . 33 m 2 /ha, spruce ( R 2 = 0 . 75 , R M S E = 6 . 73 m 2 /ha and birch ( R 2 = 0 . 71 , R M S E = 4 . 98 m 2 /ha, with total relative R M S E ( % = 29 . 66 % . In Durango, Mexico (temperate zone, Relasphone stem volume measurements were best for pine ( R 2 = 0 . 88 , R M S E = 32 . 46 m 3 /ha and total stem volume ( R 2 = 0 . 87 , R M S E = 35 . 21 m 3 /ha. Relasphone data were then successfully utilized as the only reference data in combination with optical satellite images to produce biomass maps. The Relasphone concept has been validated for future use by citizens in other locations.

  7. A Novel Approach to Wideband Spectrum Compressive Sensing Based on DST for Frequency Availability in LEO Mobile Satellite Systems

    Directory of Open Access Journals (Sweden)

    Feilong Li

    2016-01-01

    Full Text Available In LEO mobile satellite network, the L/S frequency availability is an essential task for global communication but entails several major technical challenges: high sampling rate required for wideband sensing, limited power and computing resources for processing load, and frequency-selective wireless fading. This paper investigates the issue of frequency availability in LEO mobile satellite system, and a novel wideband spectrum compressed signal detection approach is proposed to obtain active primary users (PUs subbands and their locations that should be avoided during frequency allocation. We define the novel wideband spectrum compressed sensing method based on discrete sine transform (DST-WSCS, which significantly improves the performance of spectrum detection and recovery accuracy compared with conventional discrete Fourier transform based wideband spectrum compressed sensing scheme (DFT-WSCS. Additionally, with the help of intersatellite links (ISL, the scheme of multiple satellites cooperative sensing according to OR and MAJ decision fusion rules is presented to achieve spatial diversity against wireless fading. Finally, in-depth numerical simulations are performed to demonstrate the performance of the proposed scheme in aspect of signal detection probability, reconstruction precision, processing time, and so forth.

  8. Performance evaluation of land mobile satellite system under fading and interference using multiple TCM by Monte-Carlo simulation

    Science.gov (United States)

    Kwa, S. C.; Vanderaar, Mark J.; Kim, Junghwan; Stevens, Grady H.

    1991-01-01

    The performance of the land mobile satellite system (LMSS) was evaluated by using two trellis coded modulation (TCM) schemes under multipath fading and interference. The results were also compared with uncoded QPSK. The trellis coding formats included a trellis code designed for optimum performance on the fading channel that typifies satellite to mobile communications, as well as one designed for optimum performance in the additive white Gaussian noise (AWGN) channel. The results show that, in Rayleigh fading, the TCM code designed for optimum performance in such an environment performs 4 dB better than the TCM code designed for optimum performance in AWGN, and 10 dB better than the uncoded format, at a bit error rate (BER) of 10 exp -4. Additional results on the performance degradation due to the nonlinearities in the satellite transponder and the adjacent and cochannel interference show that the TCM system is more sensitive than the uncoded system to the phase distortion caused by these impairments.

  9. Mobile satellite system fade statistics for shadowing and multipath from roadside trees at UHF and L-band

    Science.gov (United States)

    Goldhirsh, Julius; Vogel, Wolfhard J.

    1989-01-01

    Field tests related to planned mobile satellite systems were performed, and results that add to the existing database of propagation measurements at L-band (1.5 GHz) are described. They are considered particularly useful in that propagation effects were studied systematically, with repeated and controlled runs pertaining to different path elevation angles, road types, and path geometries defining shadowing and line-of-sight modes. In addition, simultaneous L-band and UHF measurements were performed for the purpose of establishing scaling factors applicable to previous UHF (870 MHz) results. The control of the experimental parameters was made possible by using a helicopter as the source platform and a mobile van to house the receiver.

  10. Spectrum availability for next generation satellite services : Coexistence with terrestrial mobile services

    NARCIS (Netherlands)

    Dekker, H.J.; Ende, A.H. van den; Gelevert, H.F.B.F.; Trommelen, P.H.

    2013-01-01

    Having available adequate and sufficient spectrum resources is a crucial factor to enable the fast growth of broadband mobile communications. Efficient use of scarce radio spectrum becomes more and more important. Especially in the lower frequency bands, with favorable conditions for mobile communic

  11. A satellite mobile communication system based on Band-Limited Quasi-Synchronous Code Division Multiple Access (BLQS-CDMA)

    Science.gov (United States)

    Degaudenzi, R.; Elia, C.; Viola, R.

    1990-01-01

    Discussed here is a new approach to code division multiple access applied to a mobile system for voice (and data) services based on Band Limited Quasi Synchronous Code Division Multiple Access (BLQS-CDMA). The system requires users to be chip synchronized to reduce the contribution of self-interference and to make use of voice activation in order to increase the satellite power efficiency. In order to achieve spectral efficiency, Nyquist chip pulse shaping is used with no detection performance impairment. The synchronization problems are solved in the forward link by distributing a master code, whereas carrier forced activation and closed loop control techniques have been adopted in the return link. System performance sensitivity to nonlinear amplification and timing/frequency synchronization errors are analyzed.

  12. Fusing Mobile In Situ Observations and Satellite Remote Sensing of Chemical Release Emissions to Improve Disaster Response

    Directory of Open Access Journals (Sweden)

    Ira Leifer

    2016-09-01

    Full Text Available Chemical release disasters have serious consequences, disrupting ecosystems, society, and causing significant loss of life. Mitigating the destructive impacts relies on identification and mapping, monitoring, and trajectory forecasting. Improvements in sensor capabilities are enabling airborne and spacebased remote sensing to support response activities. Key applications are improving transport models in complex terrain and improved disaster response.Chemical release disasters have serious consequences, disrupting ecosystems, society, and causing significant loss of life. Mitigating the destructive impacts relies on identification and mapping, monitoring, and trajectory forecasting. Improvements in sensor capabilities are enabling airborne and space-based remote sensing to support response activities. Key applications are improving transport models in complex terrain and improved disaster response.Understanding urban atmospheric transport in the Los Angeles Basin, where topographic influences on transport patterns are significant, was improved by leveraging the Aliso Canyon leak as an atmospheric tracer. Plume characterization data was collected by the AutoMObile trace Gas (AMOG Surveyor, a commuter car modified for science. Mobile surface in situ CH4 and winds were measured by AMOG Surveyor under Santa Ana conditions to estimate an emission rate of 365±30% Gg yr-1. Vertical profiles were collected by AMOG Surveyor by leveraging local topography for vertical profiling to identify the planetary boundary layer at ~700 m. Topography significantly constrained plume dispersion by up to a factor of two. The observed plume trajectory was used to validate satellite aerosol optical depth-inferred atmospheric transport, which suggested the plume first was driven offshore, but then veered back towards land. Numerical long-range transport model predictions confirm this interpretation. This study demonstrated a novel application of satellite aerosol remote

  13. NASA's Swift Satellite Catches First Supernova in The Act of Exploding

    Science.gov (United States)

    2008-05-01

    GREENBELT, Md.- Thanks to a fortuitous observation with NASA’s Swift satellite, astronomers for the first time have caught a star in the act of exploding. Astronomers have previously observed thousands of stellar explosions, known as supernovae, but they have always seen them after the fireworks were well underway. "For years we have dreamed of seeing a star just as it was exploding, but actually finding one is a once in a lifetime event," says team leader Alicia Soderberg, a Hubble and Carnegie-Princeton Fellow at Princeton University in Princeton, N.J. "This newly born supernova is going to be the Rosetta stone of supernova studies for years to come." A typical supernova occurs when the core of a massive star runs out of nuclear fuel and collapses under its own gravity to form an ultradense object known as a neutron star. The newborn neutron star compresses and then rebounds, triggering a shock wave that plows through the star’s gaseous outer layers and blows the star to smithereens. Astronomers thought for nearly four decades that this shock "break-out" will produce bright X-ray emission lasting a few minutes. X-ray Image X-ray Images But until this discovery, astronomers have never observed this signal. Instead, they have observed supernovae brightening days or weeks later, when the expanding shell of debris is energized by the decay of radioactive elements forged in the explosion. "Seeing the shock break-out in X-rays can give a direct view of the exploding star in the last minutes of its life and also provide a signpost to which astronomers can quickly point their telescopes to watch the explosion unfold," says Edo Berger, a Carnegie-Princeton Fellow at Princeton University. Soderberg's discovery of the first shock breakout can be attributed to luck and Swift's unique design. On January 9, 2008, Soderberg and Berger were using Swift to observe a supernova known as SN 2007uy in the spiral galaxy NGC 2770, located 90 million light-years from Earth in the

  14. 47 CFR 25.213 - Inter-Service coordination requirements for the 1.6/2.4 GHz mobile-satellite service.

    Science.gov (United States)

    2010-10-01

    ... MHz band shall be attenuated so that the power flux density it produces in the 1610.6-1613.8 MHz band... Mobile-Satellite Service space station operator in the 2496-2500 MHz band intends to operate at powers... system in the affected geographical region....

  15. Mobilities

    DEFF Research Database (Denmark)

    simple movements of people, goods, and information from A to B. The ‘mobilities turn’ has made it its hallmark to explore the ‘more than’ effects of a world increasingly on the move. This new title in the Routledge Series ‘Critical Concepts in Built Environment’ creates a state-of-the-art reference work......The world is on the move. This is a widespread understanding by many inhabitants of contemporary society across the Globe. But what does it actually mean? During over one decade the ‘mobilities turn’ within the social sciences have provided a new set of insights into the repercussions of mobilities...... to social networks, personal identities, and our relationship to the built environment. The omnipresence of mobilities within everyday life, high politics, technology, and tourism (to mention but a few) all point to a key insight harnessed by the ‘mobilities turn’. Namely that mobilities is much more than...

  16. System considerations and RF front-end design for integration of satellite navigation and mobile standards

    Directory of Open Access Journals (Sweden)

    A. Miskiewicz

    2009-05-01

    Full Text Available The paper presents the challenges involved in a system design of a robust reconfigurable RF front-end for navigation and mobile standards. Receiver architecture is chosen from the point of view of inter-system interference and 130nm CMOS process characteristics. System concept covers the implementation of GPS, Galileo, UMTS, GSM and CDMA2000 using a Zero-IF architecture with reconfigurable analog and digital path. Feasibility studies of the system cover analysis of the wireless regulations and performance criteria, such as overall gain, noise figure (NF, and 1dB compression point (P1dB of the RF chain, phase noise requirements and VCO tuning range [1]. The presented chip was fabricated in 130 nm CMOS technology. System considerations are confirmed with the chip measurements of gain, noise figure, and linearity. Prospects for the future work are presented including technology shrink.

  17. NASA Satellite Monitoring of Water Clarity in Mobile Bay for Nutrient Criteria Development

    Science.gov (United States)

    Blonski, Slawomir; Holekamp, Kara; Spiering, Bruce A.

    2009-01-01

    This project has demonstrated feasibility of deriving from MODIS daily measurements time series of water clarity parameters that provide coverage of a specific location or an area of interest for 30-50% of days. Time series derived for estuarine and coastal waters display much higher variability than time series of ecological parameters (such as vegetation indices) derived for land areas. (Temporal filtering often applied in terrestrial studies cannot be used effectively in ocean color processing). IOP-based algorithms for retrieval of diffuse light attenuation coefficient and TSS concentration perform well for the Mobile Bay environment: only a minor adjustment was needed in the TSS algorithm, despite generally recognized dependence of such algorithms on local conditions. The current IOP-based algorithm for retrieval of chlorophyll a concentration has not performed as well: a more reliable algorithm is needed that may be based on IOPs at additional wavelengths or on remote sensing reflectance from multiple spectral bands. CDOM algorithm also needs improvement to provide better separation between effects of gilvin (gelbstoff) and detritus. (Identification or development of such algorithm requires more data from in situ measurements of CDOM concentration in Gulf of Mexico coastal waters (ongoing collaboration with the EPA Gulf Ecology Division))

  18. Low-Cost Planar MM-Wave Phased Array Antenna for Use in Mobile Satellite (MSAT) Platforms

    DEFF Research Database (Denmark)

    Ojaroudiparchin, Naser; Shen, Ming; Pedersen, Gert F.

    2015-01-01

    In this paper, a compact 8×8 phased array antenna for mobile satellite (MSAT) devices is designed and investigated. 64-elements of 22 GHz patch antennas with coaxial-probe feeds have been used for the proposed planar design. The antenna is designed on a low-cost FR4 substrate with thickness......, dielectric constant, and loss tangent of 0.8 mm, 4.3, and 0.025, respectively. The antenna exhibits good performance in terms of impedance- matching, gain and efficiency characteristics, even though it is designed using high loss substrate with compact dimension (Wsub×Lsub=55×55 mm2). The antenna has more...... than 23 dB realized gain and -0.8 dB radiation efficiency when its beam is tilted to 0o elevation. The center frequency of the designed array can be controlled by adjusting the values of the antenna parameters. Compared with the previous designs, the proposed planar phased array has the advantages...

  19. Staging Mobilities / Designing Mobilities

    DEFF Research Database (Denmark)

    Jensen, Ole B.

    2015-01-01

    In recent years, urban research has taken a ‘mobilities turn’. There has been a developing realisation that mobilities do not ‘just happen.’ Mobilities are carefully and meticulously designed, planned and staged (from above). However, they are equally importantly acted out, performed and lived...... as people are ‘staging themselves’ (from below). Staging mobilities is a dynamic process between ‘being staged’ (for example, being stopped at traffic lights) and the ‘mobile staging’ of interacting individuals (negotiating a passage on the pavement). Staging mobilities is about the fact that mobility...... asks: what are the physical, social, technical, and cultural conditions to the staging of contemporary urban mobilities? The theoretical framing in the Staging mobilities book is applied to four in-depth cases in the accompanying volume Designing mobilities.This book explore how places, sites...

  20. Neck collar, "act-as-usual" or active mobilization for whiplash injury? A randomized parallel-group trial

    DEFF Research Database (Denmark)

    Kongsted, Alice; Montvilas, Erisela Qerama; Kasch, Helge

    2007-01-01

    Study Design. Randomized, parallel-group trial. Objective. To compare the effect of 3 early intervention strategies following whiplash injury. Summary of Background Data. Long-lasting pain and disability, known as chronic whiplash-associated disorder (WAD), may develop after a forced flexion......-extension trauma to the cervical spine. It is unclear whether this, in some cases disabling, condition can be prevented by early intervention. Active interventions have been recommended but have not been compared with information only. Methods. Participants were recruited from emergency units and general...... practitioners within 10 days after a whiplash injury and randomized to: 1) immobilization of the cervical spine in a rigid collar followed by active mobilization, 2) advice to "act-as-usual," or 3) an active mobilization program (Mechanical Diagnosis and Therapy). Follow-up was carried out after 3, 6, and 12...

  1. Neck collar, "act-as-usual" or active mobilization for whiplash injury? A randomized parallel-group trial

    DEFF Research Database (Denmark)

    Kongsted, Alice; Montvilas, Erisela Qerama; Kasch, Helge

    2007-01-01

    practitioners within 10 days after a whiplash injury and randomized to: 1) immobilization of the cervical spine in a rigid collar followed by active mobilization, 2) advice to "act-as-usual," or 3) an active mobilization program (Mechanical Diagnosis and Therapy). Follow-up was carried out after 3, 6, and 12......-extension trauma to the cervical spine. It is unclear whether this, in some cases disabling, condition can be prevented by early intervention. Active interventions have been recommended but have not been compared with information only. Methods. Participants were recruited from emergency units and general......Study Design. Randomized, parallel-group trial. Objective. To compare the effect of 3 early intervention strategies following whiplash injury. Summary of Background Data. Long-lasting pain and disability, known as chronic whiplash-associated disorder (WAD), may develop after a forced flexion...

  2. Validation and in vivo assessment of an innovative satellite-based solar UV dosimeter for a mobile app dedicated to skin health.

    Science.gov (United States)

    Morelli, M; Masini, A; Simeone, E; Khazova, M

    2016-09-31

    We present an innovative satellite-based solar UV (ultraviolet) radiation dosimeter with a mobile app interface that has been validated by exploiting both ground-based measurements and an in vivo assessment of the erythemal effects on some volunteers having controlled exposure to solar radiation. The app with this satellite-based UV dosimeter also includes other related functionalities such as the provision of safe sun exposure time updated in real-time and end exposure visual/sound alert. Both validations showed that the system has a good accuracy and reliability needed for health-related applications. This app will be launched on the market by siHealth Ltd in May 2016 under the name of "HappySun" and is available for both Android and iOS devices (more info on ). Extensive R&D activities are on-going for the further improvement of the satellite-based UV dosimeter's accuracy.

  3. Mobilization

    Science.gov (United States)

    1987-01-01

    istic and romantic emotionalism that typifies this genre. Longino, James C., et al. “A Study of World War Procurement and Industrial Mobilization...States. Harrisburg, PA: Military Service Publishing Co., 1941. CARL 355.22 J72b. Written in rough prose , this World War II era document explains the

  4. TREASURE mobile app: A satellite-enabled application for personalized heatwave risk based on location and user profile

    Science.gov (United States)

    Keramitsoglou, I.; Katsouyanni, K.; Analitis, A.; Sismanidis, P.; Kiranoudis, C. T.

    2016-12-01

    High temperatures and heatwaves are associated with large increases in mortality, especially among susceptible individuals living in urban areas. The within-city variability in the effects associated with specific area characteristics, including the Urban Heat Island effect, have to be taken into account to estimate the level of heatwave risk associated with a specific city location. Real-time appraisal and quantification of spatially distributed heatwave risk is therefore required to develop innovative applications to safeguard citizens' health. TREASURE app (http://treasure.eu-project-sites.com/) integrates the expertise of epidemiologists, Earth Observation scientists and IT developers into intelligent operational and real-time heatwave risk assessment for citizens. The app provides the user with an assessment of personalized location-specific heatwave risk. For the development of the app an epidemiological analysis of a long series of mortality data against measured data series has been carried out to identify the temperature level associated with the minimum mortality (threshold) and the change in risk of death for increases in temperature above this level, in the warm period. Published results have been also taken into account. For the estimation of heatwave hazard thermal infrared Earth Observation data were exploited so as to provide spatially and temporally detailed air and land surface temperatures. An advanced workflow has been developed that uses 4 km/5' geostationary TIR data from EUMETSAT MSG2-SEVIRI satellite, output from the Global Forecast System weather model and SAFNWC software. This workflow consists of the preprocessing of the EO data and the retrieval of LST and TA at an enhanced spatial resolution of 1km. The mobile app was developed for, evaluated in and endorsed by two Mediterranean cities with different characteristics, namely Athens (GR) and Palma (ES) and has set the ground for application to any other European city.

  5. Epac, Rap and Rab3 act in concert to mobilize calcium from sperm's acrosome during exocytosis.

    Science.gov (United States)

    Ruete, María C; Lucchesi, Ornella; Bustos, Matías A; Tomes, Claudia N

    2014-08-27

    Exocytosis of sperm's single secretory granule or acrosome (acrosome reaction, AR) is a highly regulated event essential for fertilization. The AR begins with an influx of calcium from the extracellular milieu and continues with the synthesis of cAMP and the activation of its target Epac. The cascade bifurcates into a Rab3-GTP-driven limb that assembles the fusion machinery and a Rap-GTP-driven limb that mobilizes internal calcium. To understand the crosstalk between the two signaling cascades, we applied known AR inhibitors in three experimental approaches: reversible, stage-specific blockers in a functional assay, a far-immunofluorescence protocol to detect active Rab3 and Rap, and single cell-confocal microscopy to visualize fluctuations in internal calcium stores. Our model system was human sperm with their plasma membrane permeabilized with streptolysin O and stimulated with external calcium. The inhibition caused by reagents that prevented the activation of Rap was reversed by mobilizing intracellular calcium pharmacologically, whereas that caused by AR inhibitors that impeded Rab3's binding to GTP was not. Both limbs of the exocytotic cascade joined at or near the stage catalyzed by Rab3 in a unidirectional, hierarchical connection in which the intra-acrosomal calcium mobilization arm was subordinated to the fusion protein arm; somewhere after Rab3, the pathways became independent. We delineated the sequence of events that connect an external calcium signal to internal calcium mobilization during exocytosis. We have taken advantage of the versatility of the sperm model to investigate how cAMP, calcium, and the proteinaceous fusion machinery coordinate to accomplish secretion. Because the requirement of calcium from two different sources is not unique to sperm and fusion proteins are highly conserved, our findings might contribute to elucidate mechanisms that operate in regulated exocytosis in other secretory cell types.

  6. Analysis and Simulation of the Transmission Distortions of the Mobile Digital Television DVB-SH Part 2: Satellite Mode DVB-SH-B with TDM; Part 2: Satellite Mode DVB-SH-B with TDM

    Directory of Open Access Journals (Sweden)

    L. Polak

    2012-04-01

    Full Text Available This paper deals with the second part of the latest digital TV standard DVB-SH (Digital Video Broadcasting – Satellite to Handhelds with focus on utilization of its advantages for the next generation of mobile TV broadcasting. In the second part the simulation model of DVB-SH-B, which is using satellite configuration with TDM (Time Division Multiplexing transmission mode, is presented. The work is especially focused on the description of TDM system configuration. Dependences of BER on C/N ratio for all used types of modulations are compared in the Gaussian (AWGN channel, which is generally used in DVB-SH/S2 standards for exploring of the transmission distortions. Moreover, in case of QPSK modulation, the data transmission was explored in the Ricean fading channel. Finally, achieved results are evaluated and clearly discussed.

  7. A Beam Tracking Algorithm Based on Satellite Beacon Signals for Phased Array in Mobile Satellite Communications%一种基于信标的移动卫通相控阵波束跟踪算法

    Institute of Scientific and Technical Information of China (English)

    陈鹏; 张慧

    2012-01-01

    In this paper a beam tracking algorithm based on satellite beacon signals is proposed and realized. The method is suitable for all kinds of phased array type mobile satellite communication antennas. It overcomes the difficulty of detecting the extremely weak satellite beacon signals and then the tracking performance is greatly improved. The highlight of the algorithm is the beam tracking process can be run without the help of gyroscopes and thus improves the survivability in the extreme environments. The algorithm was implemented and verified in a Ku band phased array mobile satellite antenna.%提出并实现了一种利用卫星信标信号来实施基于相控阵天线的波束跟踪算法。该方法适用于采用相控阵天线技术的各种卫星“动中通”天线,克服了卫星信标信号强度弱,检测困难的弱点,提高了跟踪信噪比,同时采用了软件无线电方式解调可以提供最大的灵活性。跟踪算法的最大优点是没有任何陀螺仪的辅助,极大地提高了天线在各种极端运动环境下的适应能力。算法最终在自行研制的Ku波段相控阵移动卫星天线系统上获得验证。

  8. Designing Mobile Applications for Emergency Response: Citizens Acting as Human Sensors.

    Science.gov (United States)

    Romano, Marco; Onorati, Teresa; Aedo, Ignacio; Diaz, Paloma

    2016-03-19

    When an emergency occurs, citizens can be a helpful support for the operation centers involved in the response activities. As witnesses to a crisis, they initially can share updated and detailed information about what is going on. Moreover, thanks to the current technological evolution people are able to quickly and easily gather rich information and transmit it through different communication channels. Indeed, modern mobile devices embed several sensors such as GPS receivers, Wi-Fi, accelerometers or cameras that can transform users into well-equipped human sensors. For these reasons, emergency organizations and small and medium enterprises have demonstrated a growing interest in developing smart applications for reporting any exceptional circumstances. In this paper, we present a practical study about this kind of applications for identifying both limitations and common features. Based on a study of relevant existent contributions in this area and our personal direct experience in developing and evaluating emergency management solutions, our aim is to propose several findings about how to design effective and efficient mobile emergency notification applications. For this purpose we have exploited the basic sensors of modern mobile devices and the users' aptitude for using them. The evaluation consists of a practical and a theoretical part. In the practical part, we have simulated a traffic accident as closely as possible to a real scenario, with a victim lying on the ground near a car in the middle of a street. For the theoretical part, we have interviewed some emergency experts for collecting their opinions about the utility of the proposed solution. Results from this evaluation phase confirm the positive impact that EN application have for both operators' and citizens' perspective. Moreover, we collected several findings useful for future design challenges in the same area, as shown in the final redesign of the proposed application.

  9. Designing Mobile Applications for Emergency Response: Citizens Acting as Human Sensors

    Directory of Open Access Journals (Sweden)

    Marco Romano

    2016-03-01

    Full Text Available When an emergency occurs, citizens can be a helpful support for the operation centers involved in the response activities. As witnesses to a crisis, they initially can share updated and detailed information about what is going on. Moreover, thanks to the current technological evolution people are able to quickly and easily gather rich information and transmit it through different communication channels. Indeed, modern mobile devices embed several sensors such as GPS receivers, Wi-Fi, accelerometers or cameras that can transform users into well-equipped human sensors. For these reasons, emergency organizations and small and medium enterprises have demonstrated a growing interest in developing smart applications for reporting any exceptional circumstances. In this paper, we present a practical study about this kind of applications for identifying both limitations and common features. Based on a study of relevant existent contributions in this area and our personal direct experience in developing and evaluating emergency management solutions, our aim is to propose several findings about how to design effective and efficient mobile emergency notification applications. For this purpose we have exploited the basic sensors of modern mobile devices and the users’ aptitude for using them. The evaluation consists of a practical and a theoretical part. In the practical part, we have simulated a traffic accident as closely as possible to a real scenario, with a victim lying on the ground near a car in the middle of a street. For the theoretical part, we have interviewed some emergency experts for collecting their opinions about the utility of the proposed solution. Results from this evaluation phase confirm the positive impact that EN application have for both operators’ and citizens’ perspective. Moreover, we collected several findings useful for future design challenges in the same area, as shown in the final redesign of the proposed application.

  10. 75 FR 44198 - Implementation of Section 203 of the Satellite Television Extension and Localism Act of 2010...

    Science.gov (United States)

    2010-07-28

    ...\\ See Cable Television Report and Order, FCC 72-108, 37 FR 3252, February 3, 1972 (adopting the concept... precondition to satellite carriage of the HD programming of an SV station affiliated with the same network. We... signal of a broadcast station access to broadcast programming via satellite.\\19\\ The 1988 SHVA...

  11. 75 FR 72968 - Implementation of Section 203 of the Satellite Television Extension and Localism Act of 2010...

    Science.gov (United States)

    2010-11-29

    ....'' \\21\\ Congress intended for the STELA to increase competition between cable and satellite providers, increase service to satellite subscribers, and update the law to reflect the completion of the digital... analog and are broadcasting only digital signals. 47 U.S.C. 309(j)(14)(A). \\23\\ STELA sec. 103...

  12. High mobility group box 1 protein as a late-acting mediator of acute lung inflammation.

    Science.gov (United States)

    Lutz, Waldemar; Stetkiewicz, Jan

    2004-01-01

    Acute inflammatory lung injury is often a delayed complication of critical illness and is associated with increased mortality. High mobility group box 1 (HMGB1) protein, in addition to its role as a transcriptional regulator factor, has been identified as a late mediator of endotoxin lethality and might be also involved in the development and progression of acute lung injury. HMGB1 protein itself can cause an acute inflammatory response manifested by increased production of proinflammatory cytokines and neutrophil accumulation. The delayed kinetics of HMGB1 protein release indicate that this protein is a distal mediator of acute inflamatory lung injury. Anti-HMGB1 protein antibodies attenuated endotoxin-induced lung injury, but not the early release of TNF-alpha and IL-1beta, indicating that HMGB1 protein is a late mediator of endotoxin-induced acute lung injury. HMGB1 protein is not released by apoptotic cells but is passively released by necrotic or damaged somatic and immune cells and it functions as a major stimulus of necrosis-induced inflammation. HMGB1 protein is also released by activated monocytes/macrophages and induces delayed and biphasic release of proinflammatory mediators from these cells. HMGB1 protein failed to stimulate cytokines release in lymphocytes, indicating that cellular stimulation is specific. We would like to suggest that HMGB1 protein may be also a primary mediator of the inflammatory responses to lung cells injury caused by toxic environmental chemicals.

  13. Two high-mobility group box domains act together to underwind and kink DNA

    Energy Technology Data Exchange (ETDEWEB)

    Sánchez-Giraldo, R.; Acosta-Reyes, F. J. [Universitat Politecnica de Catalunya, 08028 Barcelona (Spain); Malarkey, C. S. [University of Colorado School of Medicine, Aurora, CO 80045 (United States); Saperas, N. [Universitat Politecnica de Catalunya, 08028 Barcelona (Spain); Churchill, M. E. A., E-mail: mair.churchill@ucdenver.edu [University of Colorado School of Medicine, Aurora, CO 80045 (United States); Campos, J. L., E-mail: mair.churchill@ucdenver.edu [Universitat Politecnica de Catalunya, 08028 Barcelona (Spain)

    2015-06-30

    The crystal structure of HMGB1 box A bound to an unmodified AT-rich DNA fragment is reported at a resolution of 2 Å. A new mode of DNA recognition for HMG box proteins is found in which two box A domains bind in an unusual configuration generating a highly kinked DNA structure. High-mobility group protein 1 (HMGB1) is an essential and ubiquitous DNA architectural factor that influences a myriad of cellular processes. HMGB1 contains two DNA-binding domains, box A and box B, which have little sequence specificity but have remarkable abilities to underwind and bend DNA. Although HMGB1 box A is thought to be responsible for the majority of HMGB1–DNA interactions with pre-bent or kinked DNA, little is known about how it recognizes unmodified DNA. Here, the crystal structure of HMGB1 box A bound to an AT-rich DNA fragment is reported at a resolution of 2 Å. Two box A domains of HMGB1 collaborate in an unusual configuration in which the Phe37 residues of both domains stack together and intercalate the same CG base pair, generating highly kinked DNA. This represents a novel mode of DNA recognition for HMGB proteins and reveals a mechanism by which structure-specific HMG boxes kink linear DNA.

  14. N-Acylhomoserine lactones are potent neutrophil chemoattractants that act via calcium mobilization and actin remodeling.

    Science.gov (United States)

    Karlsson, Thommie; Musse, Farah; Magnusson, Karl-Eric; Vikström, Elena

    2012-01-01

    In gram-negative bacteria, cell-cell communication based on HSL QS molecules is known to coordinate the production of virulence factors and biofilms. These bacterial signals can also modulate human immune cell behavior. Using a Transwell migration assay, we found that human primary neutrophils are strongly stimulated by 3O-C(12)-HSL and -C(10)-HSL but not C(4)-HSL in a concentration-dependent manner. Moreover, 3O-C(12)-HSL and -C(10)-HSL activate PLCγ1 but not -γ2, mobilize intracellular calcium, and up-regulate IP(3)R. These changes were paralleled by F-actin accumulation, primarily in the leading edge of neutrophils, as evidenced by phalloidin staining and confocal microscopy. F- and G-actin isolation and quantification by immunoblotting revealed that the F/G-actin ratio was increased significantly after treatment with all three HSLs. Furthemore, 3O-C(12)-HSL- and 3O-C(10)-HSL treatment resulted in phosphorylation of Rac1 and Cdc42. In contrast, C(4)-HSL had negligible influence on the phosphorylation status of PLC and Rac1/Cdc42 and failed to attract neutrophils and induce calcium release. The calcium inhibitor thapsigargin, which blocks ER calcium uptake, strongly prevented neutrophil migration toward 3O-C(12)-HSL and -C(10)-HSL. These findings show that the bacterial QS molecules 3O-C(12)-HSL and -C(10)-HSL may attract human neutrophils to the sites of bacterial infection and developing biofilms. Indeed, recognition of HSL QS signals by neutrophils may play a critical role in their recruitment during infections.

  15. 75 FR 40833 - Sunshine Act Meeting; Open Commission Meeting; Thursday, July 15, 2010

    Science.gov (United States)

    2010-07-14

    ... Mobile services TECHNOLOGY, in the Mobile WIRELESS TELE- Satellite Service COMMUNICATIONS Bands at 1525... Mobile Satellite Service. 3 WIRELINE TITLE: Electronic COMPETITION. Tariff Filing System (ETFS)...

  16. Simulating Global AeroMACS Airport Ground Station Antenna Power Transmission Limits to Avoid Interference With Mobile Satellite Service Feeder Uplinks

    Science.gov (United States)

    Wilson, Jeffrey D.

    2013-01-01

    The Aeronautical Mobile Airport Communications System (AeroMACS), which is based upon the IEEE 802.16e mobile wireless standard, is expected to be implemented in the 5091 to 5150 MHz frequency band. As this band is also occupied by Mobile Satellite Service feeder uplinks, AeroMACS must be designed to avoid interference with this incumbent service. The aspects of AeroMACS operation that present potential interference are under analysis in order to enable the definition of standards that assure that such interference will be avoided. In this study, the cumulative interference power distribution at low Earth orbit from transmitters at global airports was simulated with the Visualyse Professional software. The dependence of the interference power on antenna distribution, gain patterns, duty cycle, and antenna tilt was simulated. As a function of these parameters, the simulation results are presented in terms of the limitations on transmitter power from global airports required to maintain the cumulative interference power under the established threshold.

  17. 78 FR 17430 - Notice Pursuant to the National Cooperative Research and Production Act of 1993-Open Mobile Alliance

    Science.gov (United States)

    2013-03-21

    ..., Schaumburg, IL; SK Telecom to SK Planet, Seoul; REPUBLIC OF KOREA; Sony Ericsson Mobile Communications, AB to Sony Mobile Communications AB, Stockholm, SWEDEN; and mobilkom austria AG to Telekom Austria AG, Wien...

  18. LEO 卫星通信网络的移动性管理%Mobility management in LEO satellite communication networks

    Institute of Scientific and Technical Information of China (English)

    贺达健; 游鹏; 雍少为

    2016-01-01

    近年来,低轨道(Low Earth Orbit,LEO)卫星通信网络以全球覆盖、低传输时延、低功耗链路、较强的抗毁性等特点而受到广泛关注,是未来全球移动通信系统的重要组成部分。移动性管理是构建 LEO 卫星通信网络的关键技术,为推动移动性管理问题的研究,文章从 LEO 卫星通信网络的结构和特点入手,阐述了 LEO 卫星通信网络中移动性管理的分类,并分析了其相比地面移动无线网络的特殊性。从链路层、网络层、传输层三个协议层次综述了近年来 LEO 卫星通信网络移动性管理研究的国内外现状,重点介绍了移动 IPv6(Mobile IPv6,MIPv6)和无缝 IP 分集通用移动性结构(Seamless IP-diversity based Generalized Mobility Architecture,SIGMA)在 LEO 卫星通信网络中的应用。最后,指出了移动性管理的发展趋势。%In recent years,low Earth orbit (LEO)satellite communication networks attract a lot of researchers'attention for its global coverage,short propagation delay,low-power links and great invulnerabi lity performance,etc. It wi ll be an important part of the future global mobi le communication systems.Mobi lity management is a key technology for enabling service in LEO satellite communication networks.The characteristics, research status and problems of mobi lity management were analyzed.Fi rstly,a brief classification of mobi lity management of LEO satellite communications networks was provided and characteristics distinguished from terrestrial mobi lity wi reless networks were analyzed based on the architecture and features of LEO satellite communication networks. Then the state-of-the-art mobi lity management schemes in LEO satellite communication networks were summarized from link layer,network layer and transport layer.A detai led description of the application of MIPv6 and SIGMA in LEO satellite envi ronment was given. Finally,some trends of mobi lity management of LEO satellite communications networks

  19. Fast and accurate prediction for aerodynamic forces and moments acting on satellites flying in Low-Earth Orbit

    Science.gov (United States)

    Jin, Xuhon; Huang, Fei; Hu, Pengju; Cheng, Xiaoli

    2016-11-01

    A fundamental prerequisite for satellites operating in a Low Earth Orbit (LEO) is the availability of fast and accurate prediction of non-gravitational aerodynamic forces, which is characterised by the free molecular flow regime. However, conventional computational methods like the analytical integral method and direct simulation Monte Carlo (DSMC) technique are found failing to deal with flow shadowing and multiple reflections or computationally expensive. This work develops a general computer program for the accurate calculation of aerodynamic forces in the free molecular flow regime using the test particle Monte Carlo (TPMC) method, and non-gravitational aerodynamic forces actiong on the Gravity field and steady-state Ocean Circulation Explorer (GOCE) satellite is calculated for different freestream conditions and gas-surface interaction models by the computer program.

  20. 47 CFR 25.149 - Application requirements for ancillary terrestrial components in the mobile-satellite service...

    Science.gov (United States)

    2010-10-01

    ... Policy Act of 1969, including the guidelines for human exposure to radio frequency electromagnetic fields... radiofrequency radiation exposure requirements specified in §§ 1.1307(b), 2.1091 and 2.1093 of this chapter,...

  1. Land mobile satellite transmission measurements at 869 MHz. A comparison of error probabilities for various message block durations and fade margins as a function of vegetation shadowing

    Science.gov (United States)

    Vogel, Wolfhard J.

    1985-01-01

    In order to give vehicles travelling in rural areas of the U.S. access to the telephone network, a Land Mobile Satellite System is being planned. Previously presented data by the author were analyzed for the probability that the received signal level dropped below a threshold during short time blocks of various signal durations and the conditional probability that such an event would reoccur after a given delay. If it assumed that a fade threshold crossing of even 1 msec would produce an error in the transmission, then the derived quantities can be considered error probabilities. Extensive tables and graphs are presented with the results from the analysis. They can be used to devise communication strategies which will provide improved link availability in the presence of vegetation shadowing.

  2. The Causal Effect of Student Mobility on Standardized Test Performance: A Case Study with Possible Implications for Accountability Mandates within the Elementary and Secondary Education Act.

    Science.gov (United States)

    Selya, Arielle S; Engel-Rebitzer, Eden; Dierker, Lisa; Stephen, Eric; Rose, Jennifer; Coffman, Donna L; Otis, Mindy

    2016-01-01

    This paper presents a limited case study examining the causal inference of student mobility on standardized test performance, within one middle-class high school in suburban Connecticut. Administrative data were used from a district public high school enrolling 319 10th graders in 2010. Propensity score methods were used to estimate the causal effect of student mobility on Math, Science, Reading, and Writing portions of the Connecticut Academic Performance Test (CAPT), after matching mobile vs. stable students on gender, race/ethnicity, eligibility for free/reduced lunches, and special education status. Analyses showed that mobility was associated with lower performance in the CAPT Writing exam. Follow-up analyses revealed that this trend was only significant among those who were ineligible for free/reduced lunches, but not among eligible students. Additionally, mobile students who were ineligible for free/reduced lunches had lower performance in the CAPT Science exam according to some analyses. Large numbers of students transferring into a school district may adversely affect standardized test performance. This is especially relevant for policies that affect student mobility in schools, given the accountability measures in the No Child Left Behind that are currently being re-considered in the recent Every Student Succeeds Act.

  3. The Causal Effect of Student Mobility on Standardized Test Performance: A Case Study with Possible Implications for Accountability Mandates within the Elementary and Secondary Education Act

    Directory of Open Access Journals (Sweden)

    Arielle Selya

    2016-07-01

    Full Text Available This paper presents a limited case study examining the causal inference of student mobility on standardized test performance, within one middle-class high school in suburban Connecticut. Administrative data were used from a district public high school enrolling 319 10th graders in 2010. Propensity score methods were used to estimate the causal effect of student mobility on Math, Science, Reading, and Writing portions of the Connecticut Academic Performance Test (CAPT, after matching mobile vs. stable students on gender, race/ethnicity, eligibility for free/reduced lunches, and special education status. Analyses showed that mobility was associated with lower performance in the CAPT Writing exam. Follow-up analyses revealed that this trend was only significant among those who were ineligible for free/reduced lunches, but not among eligible students. Additionally, mobile students who were ineligible for free/reduced lunches had lower performance in the CAPT Science exam according to some analyses. Large numbers of students transferring into a school district may adversely affect standardized test performance. This is especially relevant for policies that affect student mobility in schools, given the accountability measures in the No Child Left Behind that are currently being re-considered in the recent Every Student Succeeds Act.

  4. CSIR South Africa mobile LIDAR—First scientific results: comparison with satellite, sun photometer and model simulations

    OpenAIRE

    Bollig, C.; Mengistu, G.; Sharma, A.; W. Alemu; D. Moema; Tesfaye, M; Sivakumar, V

    2010-01-01

    We present the first scientific results from the Council for Scientific and Industrial Research–National Laser Centre (CSIR-NLC) mobile LIght Detection And Ranging (LIDAR) and its validation and comparison with other ground-based and space-borne measurements. The LIDAR results are compared with aerosol extinction measurements from the Stratosphere Aerosol Gas Experiment (SAGE) II, optical depth derived from sun photometers employed under the AErosol RObotic NETwork (AERONET) and backscatter c...

  5. The rise and fall of COMSAT technology, business, and government in satellite communications

    CERN Document Server

    Whalen, D

    2014-01-01

    Satellite communications grosses over 100 billion annually and is heading toward 200 billion. COMSAT started all of this in 1963 when it was organized in compliance with the Communications Satellite Act of 1962. COMSAT was responsible for choosing geosynchronous earth orbit (GEO), forming INTELSAT, and generally promoting the technological change that saw satellite power increase from the 40 watts of Early Bird (INTELSAT I) to the almost 10 kilowatts of INTELSAT IX; earth station antennas were reduced from 30 meters to 1 meter. The business of satellite communications was expanded to mobile co

  6. Research on Application Performance of Vehicle-mounted Station of Satellite Mobile Communication%卫星移动通信车载站应用性能研究

    Institute of Scientific and Technical Information of China (English)

    汪洋

    2012-01-01

    在对各类卫星移动通信系统性能分析比较的基础上,从系统造价和可实现程度的角度考虑,同步静止轨道(GEO)系统更适合于区域覆盖卫星移动通信系统,卫星移动通信车载站(简称动中通)是实现地面卫星移动通信系统的关键设备。给出了动中通系统设计中卫星转发器带宽占用率和功率占用率的计算,对动中通站型能力和天线口径的选取进行了分析和讨论,并结合相关计算给出了动中通站型和天线选取的建议。%Based on the system performance comparison among some kinds of satellite mobile communication systems and the consideration of the cost and the extent of realization,the GEO system is more propitious to regional satellite mobile communication system. Vehicle-mounted station of satellite mobile communication is the key device to realize land mobile satellite communication system. The calculation methods of occupancy rates of bandwidth and power of satellite transponder in mobile communication system design are described in this paper. How to choose the size of antenna and the type of the station is analyzed and discussed. Some suggestions are given for choosing antenna and type of the station.

  7. CSIR South Africa mobile LIDAR—First scientific results: comparison with satellite, sun photometer and model simulations

    Directory of Open Access Journals (Sweden)

    C. Bollig

    2010-02-01

    Full Text Available We present the first scientific results from the Council for Scientific and Industrial Research–National Laser Centre (CSIR-NLC mobile LIght Detection And Ranging (LIDAR and its validation and comparison with other ground-based and space-borne measurements. The LIDAR results are compared with aerosol extinction measurements from the Stratosphere Aerosol Gas Experiment (SAGE II, optical depth derived from sun photometers employed under the AErosol RObotic NETwork (AERONET and backscatter coefficients simulated from weather balloon humidity measurements.

  8. Mobility Divides

    DEFF Research Database (Denmark)

    Jensen, Ole B.

    Contemporary mobilities are cultural and social manifestations, and the mobile practices in the everyday life of billions of humans are re-configuring senses of place, self, other and relationships to the built environment. The way ‘mobile situations’ are staged in designed and built environments...... are increasingly becoming ‘second nature’ but also expressions of power, exclusion, and difference. In this talk I will be applying a perspective of ‘mobile situationism’ illustrating how mobile everyday life practices are staged ‘from above’ in planning and policy frameworks, design codes and architectural...... designs, but also how the situated and embodied mobile everyday life practices are staged ‘from below’ in concrete acts of choice concerning modes of mobilities, ways of moving and interacting. The ‘staging mobilites’ framework opens up to an understanding of the meaning of ‘mobilities design...

  9. Mobility Divides

    DEFF Research Database (Denmark)

    Jensen, Ole B.

    Contemporary mobilities are cultural and social manifestations, and the mobile practices in the everyday life of billions of humans are re-configuring senses of place, self, other and relationships to the built environment. The way ‘mobile situations’ are staged in designed and built environments...... are increasingly becoming ‘second nature’ but also expressions of power, exclusion, and difference. In this talk I will be applying a perspective of ‘mobile situationism’ illustrating how mobile everyday life practices are staged ‘from above’ in planning and policy frameworks, design codes and architectural...... designs, but also how the situated and embodied mobile everyday life practices are staged ‘from below’ in concrete acts of choice concerning modes of mobilities, ways of moving and interacting. The ‘staging mobilites’ framework opens up to an understanding of the meaning of ‘mobilities design...

  10. Mobile Probes in Mobile Learning

    DEFF Research Database (Denmark)

    Ørngreen, Rikke; Blomhøj, Ulla; Duvaa, Uffe

    as an agent for acquiring empirical data (as the situation in hitherto mobile probe settings) but was also the technological medium for which data should say something about (mobile learning). Consequently, not only the content of the data but also the ways in which data was delivered and handled, provided......In this paper experiences from using mobile probes in educational design of a mobile learning application is presented. The probing process stems from the cultural probe method, and was influenced by qualitative interview and inquiry approaches. In the project, the mobile phone was not only acting...... a valuable dimension for investigating mobile use. The data was collected at the same time as design activities took place and the collective data was analysed based on user experience goals and cognitive processes from interaction design and mobile learning. The mobile probe increased the knowledge base...

  11. The 2002 rock/ice avalanche at Kolka/Karmadon, Russian Caucasus: assessment of extraordinary avalanche formation and mobility, and application of QuickBird satellite imagery

    Directory of Open Access Journals (Sweden)

    C. Huggel

    2005-01-01

    Full Text Available A massive rock/ice avalanche of about 100x106m3 volume took place on the northern slope of the Kazbek massif, North Ossetia, Russian Caucasus, on 20 September 2002. The avalanche started as a slope failure, that almost completely entrained Kolka glacier, traveled down the Genaldon valley for 20km, was stopped at the entrance of the Karmadon gorge, and was finally succeeded by a distal mudflow which continued for another 15km. The event caused the death of ca. 140 people and massive destruction. Several aspects of the event are extraordinary, i.e. the large ice volume involved, the extreme initial acceleration, the high flow velocity, the long travel distance and particularly the erosion of a valley-type glacier, a process not known so far. The analysis of these aspects is essential for process understanding and worldwide glacial hazard assessments. This study is therefore concerned with the analysis of processes and the evaluation of the most likely interpretations. The analysis is based on QuickBird satellite images, field observations, and ice-, flow- and thermo-mechanical considerations. QuickBird is currently the best available satellite sensor in terms of ground resolution (0.6 m and opens new perspectives for assessment of natural hazards. Evaluation of the potential of QuickBird images for assessment of high-mountain hazards shows the feasibility for detailed avalanche mapping and analysis of flow dynamics, far beyond the capabilities of conventional satellite remote sensing. It is shown that the avalanche was characterized by two different flows. The first one was comparable to a hyperconcentrated flow and was immediately followed by a flow with a much lower concentration of water involving massive volumes of ice. The high mobility of the avalanche is likely related to fluidization effects at the base of the moving ice/debris mass with high pore pressures and a continuous supply of water due to frictional melting of ice. The paper

  12. The System Design and Function Realization of Shipborne Mobile Satellite Communication System%船载动中通系统设计与功能实现

    Institute of Scientific and Technical Information of China (English)

    席永帅; 章凌凡; 吴芳伟

    2016-01-01

    According to the shortage of the existing maritime communication, we expounds the advantage of shipborne mobile satellite communication systems in communication between ship and shore, also between ship and ship. By moving through the partical application of this system, we introduce the system composition and the working principle of the system. We also discuss the key technology in this field. In the end, the technical assistance of maritime communication service is provided.%依据现有海上常用通信方式的不足,阐述了以卫星为通信手段的船载动中通卫星通信系统在船舶与陆地、船舶与船舶之间通信的优势,通过动中通卫星通信系统的具体应用实例,介绍了系统组成、系统工作原理,探讨了动中通中的关键技术,为保障更优质的海上通信服务提供技术支持。

  13. Staging Mobilities

    DEFF Research Database (Denmark)

    Jensen, Ole B.

    that mobility is more than movement between point A and B. It explores how the movement of people, goods, information, and signs influences human understandings of self, other and the built environment. Moving towards a new understanding of the relationship between movement, interaction and environments......In recent years, the social sciences have taken a “mobilities turn.” There has been a developing realisation that mobilities do not “just happen.” Mobilities are carefully and meticulously designed, planned and staged (from above). However, they are equally importantly acted out, performed...... and lived as people are “staging themselves” (from below). Staging mobilities is a dynamic process between “being staged” (for example, being stopped at traffic lights) and the “mobile staging” of interacting individuals (negotiating a passage on the pavement). Staging Mobilities is about the fact...

  14. Going mobile

    Science.gov (United States)

    Brus, Eric

    1987-12-01

    By 1990, all metropolitan areas in the U.S. and rural areas close to major cities or towns are expected to have cellular telephone service; 22 Canadian cities also feature cellular service. To supply mobile telecommunication services to sparsely-populated rural areas, a mobile satellite service (MSS) is now being developed. In this paper the projected possibilities of the MSS system are discussed, including a possibility that a piggyback-MSS payload be added to the GSTAR-4 satellite which is scheduled for a launch in 1988 or 1989; one in which some of the hardware from aborted direct-broadcast satellites would be used; and the possibility of building a new MSS satellite with large servicing capacity. Canada is planning to launch its own mobile satellite, MSAT, in the early 1990s. The MSS is expected to be 'generic', serving not only people on land but maritime and aeronautical users as well. It will also offer major benefits to truck and automobile drivers, making it possible for them to conduct business or to call for assistance from locations beyond the range of cellular systems.

  15. Mobilities Mobilities

    Directory of Open Access Journals (Sweden)

    César Pompeyo

    2011-12-01

    Full Text Available Urry, John (2007 Mobilities.Oxford: Polity Press.Urry, John (2007 Mobilities.Oxford: Polity Press.John Urry (1946-, profesor en la Universidad de Lancaster, es un sociólogo de sobra conocido y altamente reputado en el panorama internacional de las ciencias sociales. Su dilatada carrera, aparentemente dispersa y diversificada, ha seguido senderos bastante bien definidos dejando tras de sí un catálogo extenso de obras sociológicas de primer nivel. Sus primeros trabajos se centraban en el campo de la teoría social y la filosofía de las ciencias sociales o de la sociología del poder [...

  16. 在卫星移动信道中不同条件下 Turbo码的纠错性能研究%Study on error-correction performance of Turbo codes in mobile satellite channel under different fading conditions

    Institute of Scientific and Technical Information of China (English)

    童新海; 甘仲民; 杨喜根

    2001-01-01

    研究了采用Turbo码技术的抗衰落性能,首先分析了Turbo码在卫星移动遮蔽Rician衰落信道下的误差纠错性能限,然后通过计算机仿真模拟了三种不同的卫星移动衰落信道下Turbo码的性能,研究了不同衰落信道特性对Turbo码性能的影响情况,同时还讨论了在衰落信道下Turbo码的子码约束长度和交织器长度两个主要参数对性能的影响情况。%In this paper, theoretical analysis of error rate performance about Turbocode on Mobile satellite shadowed Rician fading channel is presented. And comparison with the performance on AWGN is discussed. The simulation results by computer on three different mobile satellite fading channel is also presented. The influence on Turbocode performance of different fading channel characteristic is highlighted. In the meantime, the roles of two Turbocode main parametersconstitute code constraint length and the interleaver lengthon Mobile satellite shadowed fading channel is discussed.

  17. Scalable and Cost-Effective Assignment of Mobile Crowdsensing Tasks Based on Profiling Trends and Prediction: The ParticipAct Living Lab Experience

    Directory of Open Access Journals (Sweden)

    Paolo Bellavista

    2015-07-01

    Full Text Available Nowadays, sensor-rich smartphones potentially enable the harvesting of huge amounts of valuable sensing data in urban environments, by opportunistically involving citizens to play the role of mobile virtual sensors to cover Smart City areas of interest. This paper proposes an in-depth study of the challenging technical issues related to the efficient assignment of Mobile Crowd Sensing (MCS data collection tasks to volunteers in a crowdsensing campaign. In particular, the paper originally describes how to increase the effectiveness of the proposed sensing campaigns through the inclusion of several new facilities, including accurate participant selection algorithms able to profile and predict user mobility patterns, gaming techniques, and timely geo-notification. The reported results show the feasibility of exploiting profiling trends/prediction techniques from volunteers’ behavior; moreover, they quantitatively compare different MCS task assignment strategies based on large-scale and real MCS data campaigns run in the ParticipAct living lab, an ongoing MCS real-world experiment that involved more than 170 students of the University of Bologna for more than one year.

  18. Dual-Stack Single-Radio Communication Architecture for UAV Acting As a Mobile Node to Collect Data in WSNs

    Science.gov (United States)

    Sayyed, Ali; Medeiros de Araújo, Gustavo; Bodanese, João Paulo; Buss Becker, Leandro

    2015-01-01

    The use of mobile nodes to collect data in a Wireless Sensor Network (WSN) has gained special attention over the last years. Some researchers explore the use of Unmanned Aerial Vehicles (UAVs) as mobile node for such data-collection purposes. Analyzing these works, it is apparent that mobile nodes used in such scenarios are typically equipped with at least two different radio interfaces. The present work presents a Dual-Stack Single-Radio Communication Architecture (DSSRCA), which allows a UAV to communicate in a bidirectional manner with a WSN and a Sink node. The proposed architecture was specifically designed to support different network QoS requirements, such as best-effort and more reliable communications, attending both UAV-to-WSN and UAV-to-Sink communications needs. DSSRCA was implemented and tested on a real UAV, as detailed in this paper. This paper also includes a simulation analysis that addresses bandwidth consumption in an environmental monitoring application scenario. It includes an analysis of the data gathering rate that can be achieved considering different UAV flight speeds. Obtained results show the viability of using a single radio transmitter for collecting data from the WSN and forwarding such data to the Sink node. PMID:26389911

  19. Dual-Stack Single-Radio Communication Architecture for UAV Acting As a Mobile Node to Collect Data in WSNs.

    Science.gov (United States)

    Sayyed, Ali; de Araújo, Gustavo Medeiros; Bodanese, João Paulo; Becker, Leandro Buss

    2015-09-16

    The use of mobile nodes to collect data in a Wireless Sensor Network (WSN) has gained special attention over the last years. Some researchers explore the use of Unmanned Aerial Vehicles (UAVs) as mobile node for such data-collection purposes. Analyzing these works, it is apparent that mobile nodes used in such scenarios are typically equipped with at least two different radio interfaces. The present work presents a Dual-Stack Single-Radio Communication Architecture (DSSRCA), which allows a UAV to communicate in a bidirectional manner with a WSN and a Sink node. The proposed architecture was specifically designed to support different network QoS requirements, such as best-effort and more reliable communications, attending both UAV-to-WSN and UAV-to-Sink communications needs. DSSRCA was implemented and tested on a real UAV, as detailed in this paper. This paper also includes a simulation analysis that addresses bandwidth consumption in an environmental monitoring application scenario. It includes an analysis of the data gathering rate that can be achieved considering different UAV flight speeds. Obtained results show the viability of using a single radio transmitter for collecting data from the WSN and forwarding such data to the Sink node.

  20. Dual-Stack Single-Radio Communication Architecture for UAV Acting As a Mobile Node to Collect Data in WSNs

    Directory of Open Access Journals (Sweden)

    Ali Sayyed

    2015-09-01

    Full Text Available The use of mobile nodes to collect data in a Wireless Sensor Network (WSN has gained special attention over the last years. Some researchers explore the use of Unmanned Aerial Vehicles (UAVs as mobile node for such data-collection purposes. Analyzing these works, it is apparent that mobile nodes used in such scenarios are typically equipped with at least two different radio interfaces. The present work presents a Dual-Stack Single-Radio Communication Architecture (DSSRCA, which allows a UAV to communicate in a bidirectional manner with a WSN and a Sink node. The proposed architecture was specifically designed to support different network QoS requirements, such as best-effort and more reliable communications, attending both UAV-to-WSN and UAV-to-Sink communications needs. DSSRCA was implemented and tested on a real UAV, as detailed in this paper. This paper also includes a simulation analysis that addresses bandwidth consumption in an environmental monitoring application scenario. It includes an analysis of the data gathering rate that can be achieved considering different UAV flight speeds. Obtained results show the viability of using a single radio transmitter for collecting data from the WSN and forwarding such data to the Sink node.

  1. Atos de cidadania europeia: uma sociologia política da mobilidade Acts of European citizenship: a political sociology of mobility

    Directory of Open Access Journals (Sweden)

    Claudia Aradau

    2011-06-01

    Full Text Available A cidadania europeia é marcada por uma tensão entre uma cidadania derivativa do Estado-nação e uma cidadania definida pela liberdade de movimento. Abordando essa tensão como sintomática de uma profunda contradição entre integração e mobilidade que é constitutiva das formações sociais modernas, este artigo desenvolve uma sociologia política da mobilidade que desafia as considerações territoriais e culturalistas sobre a cidadania europeia. Isso é feito explorando a representação política da cidadania europeia por parte de sujeitos marginalizados, cujo engajamento em relações de troca serve como lugar para atos de cidadania europeia que "mobilizam a mobilidade". Isso é ilustrado por uma análise da Declaração dos Direitos dos Trabalhadores Sexuais na Europa, de 2005.European citizenship is marked by a tension: between a citizenship that is derivative of the nation-state and a citizenship that is defined by free movement. Approaching this tension as symptomatic of a deep-rooted contradiction between integration and mobility that is constitutive of modern social formations, this article develops a political sociology of mobility that challenges territorial and culturalist accounts of European citizenship. It does so by exploring the political enactment of European citizenship by marginalized subjects, whose engagement in relations of exchange serve as the ground for acts of European citizenship that 'mobilize mobility'. This is illustrated by an analysis of the 2005 Declaration for the Rights of Sex Workers in Europe.

  2. National Security/Emergency Preparedness and Disaster Recovery Communications Via ACTS

    Science.gov (United States)

    Pasqualino, Christopher R.; Abbe, Brian S.; Dixon, Frank

    1996-01-01

    During the period from early 1993 through 1994, the U.S. National Communication System, a government agency, sponsored the development and execution of several fixed and mobile experiments using the Advanced Communications Technology Satellite (ACTS)...The results of these experiments are described in this paper.

  3. Staging Mobilities

    DEFF Research Database (Denmark)

    Jensen, Ole B.

    In recent years, the social sciences have taken a “mobilities turn.” There has been a developing realisation that mobilities do not “just happen.” Mobilities are carefully and meticulously designed, planned and staged (from above). However, they are equally importantly acted out, performed...... that mobility is more than movement between point A and B. It explores how the movement of people, goods, information, and signs influences human understandings of self, other and the built environment. Moving towards a new understanding of the relationship between movement, interaction and environments......, the book asks: what are the physical, social, technical, and cultural conditions to the staging of contemporary urban mobilities?...

  4. Designing Mobilities

    DEFF Research Database (Denmark)

    Jensen, Ole B.

    How is the width of the pavement shaping the urban experience? How is the material design of transport infrastructure and mobile technology affording social interaction in everyday life spaces? How do people inhabit these spaces with their bodies and in accordance to social and cultural norms......? These are some of the questions that this book raises in order to explore how the design of mobile sites and situations affect people's everyday life. The book takes point of departure in the author's book 'Staging Mobilities' (Routledge, 2013) in which it is argued that mobility is much more than simple...... acts of moving in the city. 'Designing Mobilities' is based on more than a decade of academic research by Professor of Urban Theory, Ole B. Jensen and a must-read for students and scholars with an interest in urban studies, urban design, architecture, urban planning, transport planning and geography...

  5. The Archimedes satellite system

    Science.gov (United States)

    Taylor, Stuart C.; Shurvinton, William D.

    1992-03-01

    Archimedes is a satellite system conceived by the European Space Agency (ESA) to effectively serve the European market for Mobile Radio Services (MRS). This paper describes the requirements and technical design of the Archimedes satellite system. The underlying assumptions and trade-offs behind the design are detailed and the design is compared and contrasted against alternative design solutions, both technically and economically. A path forward for the development of the system is indicated.

  6. 广东省防汛卫星移动通信系统的设计与实现%Design and Implementation of Flood Control and Satellite Mobile Communication System in Guangdong Province

    Institute of Scientific and Technical Information of China (English)

    朱识

    2015-01-01

    利用卫星通信,结合3G/4G蜂窝移动通信,设计并实现广东省防汛指挥应急调度卫星移动通信系统。系统由现场视频手机、蜂窝3G/4G移动通信和卫星BGAN网络、指挥中心自动视频接收播放终端组成,已在广东省防汛应急指挥调度中应用,现场人员通过高速3G/4G 移动或卫星通信安全接入广东省水利信息网络系统,可以随时随地传送现场视频和进行会商指挥调度,对提升全省三防应急会商决策、指挥调度的效率有重要的推动作用。%This project is aimed to design and establish a mobile satellite communication system for lfood control and emergency command of Guangdong Province through the combination of satellite communication and 3G/4G cellular mobile communication. This system consists of live video phone, 3G/4G cellular mobile communication, satellite BGAN network and a terminal in command center for automatically receiving and broadcasting video. With the system applied to the lfood control and emergency command of Guangdong Province, ifeld staff can get access to Water Resources Information Network System of Guangdong Province through high-speed 3G/4G mobile communication and satellite communication, and therefore consultation and command as well as transmission of live videos are made possible whenever and wherever needed, which promotes the efficiency of consultation on three anti-emergency, decision-making and scheduling of Guangdong Province.

  7. Satellite Communication.

    Science.gov (United States)

    Technology Teacher, 1985

    1985-01-01

    Presents a discussion of communication satellites: explains the principles of satellite communication, describes examples of how governments and industries are currently applying communication satellites, analyzes issues confronting satellite communication, links mathematics and science to the study of satellite communication, and applies…

  8. Satellite orbit determination and gravity field recovery from satellite-to-satellite tracking

    Science.gov (United States)

    Wakker, K. F.; Ambrosius, B. A. C.; Leenman, H.

    1989-07-01

    Studies on satellite-to-satellite tracking (SST) with POPSAT (a geodetic satellite concept) and a ERS-class (Earth observation) satellite, a Satellite-to-Satellite Tracking (SST) gravity mission, and precise gravity field determination methods and mission requirements are reported. The first two studies primarily address the application of SST between the high altitude POPSAT and an ERS-class or GRM (Geopotential Research Mission) satellite to the orbit determination of the latter two satellites. Activities focussed on the determination of the tracking coverage of the lower altitude satellite by ground based tracking systems and by POPSAT, orbit determination error analysis and the determination of the surface forces acting on GRM. The third study surveys principles of SST, uncertainties of existing drag models, effects of direct luni-solar attraction and tides on orbit and the gravity gradient observable. Detailed ARISTOTELES (which replaced POPSAT) orbit determination error analyses were performed for various ground based tracking networks.

  9. 移动卫星网络中卫星切换调度研究%Research on the Handover Scheduling in Mobile Satellite Communication Networks

    Institute of Scientific and Technical Information of China (English)

    吴兆峰; 胡谷雨; 金凤林

    2015-01-01

    针对卫星切换调度问题,提出了一种最大服务时长切换调度算法。该算法利用了现有的GPS基础设施和卫星网络中卫星的多样性(即在任意时刻多颗卫星覆盖相同的区域),减少了用户在通信过程中的切换次数,从而最终降低了用户的掉话率,实现了用户在低轨( LEO)卫星网络中实时高效的切换。在Iridium卫星网络中的仿真结果验证了该算法的有效性。%A new satellite handover scheduling algorithm based on the maximum residual service time was proposed. The algorithm exploits both global positioning system ( GPS) infrastructure and satellite diversi-ty, providing a simple and real-time handover management in low earth orbit ( LEO) satellite networks to minimize the expected number of satellite handovers. It reduces the users' call drop probability ultimate-ly. Simulations were carried out on the typical Iridium satellite network and the simulation results corrob-orate the advantages gained by the proposed algorithm.

  10. Fade-Free Mobile Communication

    Science.gov (United States)

    Stevenson, C. R.

    1986-01-01

    Scheme for mobile communication reduces multipath fading and interference between adjacent channels. Proposed communication system lends itself to almost completely digital implementation, eliminating costly and bulky crystal filters. Scheme suitable for satellite-aided or terrestrial mobile communication, including cellular mobile telephony, at frequencies in 150-to-900-MHz range.

  11. Global Satellite Mobile Communication Constellation System Space-based Inter-satellite-link TC&R Scheme%全球卫星移动通信星座天基星间链路测控方案

    Institute of Scientific and Technical Information of China (English)

    杨童; 吴雨翔; 李明峰

    2013-01-01

    针对全球卫星通信星座的测控问题,提出了利用静止轨道卫星作为天基测控网对低轨全球通信星座卫星进行测控的方案,在GEO轨道布置3颗地球静止轨道卫星,建立GEO轨道卫星与LEO星座卫星之间的星间链路来传输测控信息,再将这些信息转发至相应的地面测控站,分析了测控链路的传输指标,评估了星间测控链路的双向传输性能,最后通过仿真分析验证了采用3颗静止轨道卫星组成的天基测控网能够大幅拓展单纯依靠传统陆基测控网的测控可见弧段,其24h测控弧段覆盖率是后者的8倍,总测控时间比后者提升大约10倍.%A novel telemetry,control and ranging (TC&R) scheme was proposed,adopting space-based GEO satellites' inter-satellite-link(ISL).A space-based TC&R network was established by launching 3 GEO satellites,transmitting and receiving various signals through ISL between LEO and GEO satellites,and retransmitting signals to the ground facilities.The link performance,forward and return link budget capability,and the coverage area analysis were studied.The simulation results show that the GEO space-based TC&R beam,formed by 3 GEO satellites,is capable of creating a much wider coverage area than the ordinary terrestrial-based one,which remarkably extends the TC&R coverage area by 8 times during a 24-hour computing period,and the total TC&R mission performing time is almost 10 times in comparison with the ordinary scheme.

  12. Mobile Router Technology Development

    Science.gov (United States)

    Ivancic, William D.; Stewart, David H.; Bell, Terry L.; Kachmar, Brian A.; Shell, Dan; Leung, Kent

    2002-01-01

    Cisco Systems and NASA have been performing joint research on mobile routing technology under a NASA Space Act Agreement. Cisco developed mobile router technology and provided that technology to NASA for applications to aeronautic and space-based missions. NASA has performed stringent performance testing of the mobile router, including the interaction of routing and transport-level protocols. This paper describes mobile routing, the mobile router, and some key configuration parameters. In addition, the paper describes the mobile routing test network and test results documenting the performance of transport protocols in dynamic routing environments.

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

    Science.gov (United States)

    Pepin, Gerard R.; Hager, E. Paul

    1991-01-01

    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.

  14. DREAM Act, citizenship, and mobilization

    NARCIS (Netherlands)

    Nicholls, W.J.; Ness, I.

    2013-01-01

    The late 2000s marked an important shift in the immigrant rights movement. It was the period in which undocumented youths became an organized constituency and moved to assert their power within the general immigrant rights movement. Undocumented immigrants had long been represented by professional

  15. DREAM Act, citizenship, and mobilization

    NARCIS (Netherlands)

    Nicholls, W.J.; Ness, I.

    2013-01-01

    The late 2000s marked an important shift in the immigrant rights movement. It was the period in which undocumented youths became an organized constituency and moved to assert their power within the general immigrant rights movement. Undocumented immigrants had long been represented by professional r

  16. 移动通信基站对C波段卫星信号接收的影响%Mobile Communication base Station of C-band Satellite Reception

    Institute of Scientific and Technical Information of China (English)

    李世杰

    2014-01-01

    卫星信号的传输,不可避免地会受到各种电磁波干扰,通过对宁波电视台C波段卫星信号被干扰情况的分析、查找,针对移动通信基站对C波段卫星电视信号的干扰进行分析,并提出解决办法。%Satellite signal transmission is affected inevitably by various kinds of electromagnetic interference . This article proposes a resolution for interference to C-band satellite signal at Ningbo TV station ,which is based on detail analysis on interference by mobile communication base stations .

  17. Broadcast satellite service: The international dimension

    Science.gov (United States)

    Samara, Noah

    1991-09-01

    The dawn of the 1990's has witnessed the birth of a new satellite service - satellite sound broadcasting. This new service is characterized by digital transmission at data rates up to 256 kb/s from satellites in geostationary orbit to small, low-cost, mobile and portable receivers. The satellite sound broadcasting service is a logical step beyond navigation satellite service, such as that provided by the GPS Navstar system. The mass market appeal of satellite sound broadcasting in the area of lightsat technology and low-cost digital radios has greatly facilitated the financing of this type of space service.

  18. Plan of advanced satellite communication experiments using ETS-6

    Science.gov (United States)

    Ikegami, Tetsushi

    1989-01-01

    In 1992, an Engineering Test Satellite 6 is scheduled to be launched by an H-2 rocket. The missions of ETS-6 are to establish basic technologies of inter-satellite communications using S-band, millimeter waves and optical beams and of fixed and mobile satellite communications using multibeam antenna on board the satellite. A plan of the experiments is introduced.

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

    Science.gov (United States)

    Pepin, Gerard R.

    1992-01-01

    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.

  20. Modeling C-Band Co-Channel Interference From AeroMACS Omni-Directional Antennas to Mobile Satellite Service Feeder Uplinks

    Science.gov (United States)

    Wilson, Jeffrey D.

    2011-01-01

    A new C-band (5091 to 5150 MHz) airport communications system designated as Aeronautical Mobile Airport Communications System (AeroMACS) is being planned under the Federal Aviation Administration s NextGen program. An interference analysis software program, Visualyse Professional (Transfinite Systems Ltd), is being utilized to provide guidelines on limitations for AeroMACS transmitters to avoid interference with other systems. A scenario consisting of a single omni-directional transmitting antenna at each of the major contiguous United States airports is modeled and the steps required to build the model are reported. The results are shown to agree very well with a previous study.

  1. Satellite Communications for ATM

    Science.gov (United States)

    Shamma, Mohammed A.

    2003-01-01

    This presentation is an overview on Satellite Communication for the Aeronautical Telecommunication Management (ATM) research. Satellite Communications are being considered by the FAA and NASA as a possible alternative to the present and future ground systems supporting Air Traffic Communications. The international Civil Aviation Organization (ICAO) have in place Standards and Recommended Practices (SARPS) for the Aeronautical Mobile Satellite Services (AMSS) which is mainly derived from the pre-existing Inmarsat service that has been in service since the 1980s. The Working Group A of the Aeronautical Mobile Communication Panel of ICAO has also been investigating SARPS for what is called the Next Generation Satellite Service (NGSS) which conforms less to the Inmarsat based architecture and explores wider options in terms of satellite architectures. Several designs are being proposed by Firms such as Boeing, ESA, NASA that are geared toward full or secondary usage of satellite communications for ATM. Satellite communications for ATM can serve several purposes ranging from primary usage where ground services would play a minimal backup role, to an integrated solution where it will be used to cover services, or areas that are less likely to be supported by the proposed and existing ground infrastructure. Such Integrated roles can include usage of satellite communications for oceanic and remote land areas for example. It also can include relieving the capacity of the ground network by providing broadcast based services of Traffic Information Services messages (TIS-B), or Flight Information Services (FIS-B) which can take a significant portion of the ground system capacity. Additionally, satellite communication can play a backup role to support any needs for ground replacement, or additional needed capacity even after the new digital systems are in place. The additional bandwidth that can be provided via satellite communications can also open the door for many new

  2. Mobile marketing for mobile games

    OpenAIRE

    Vu, Giang

    2016-01-01

    Highly developed mobile technology and devices enable the rise of mobile game industry and mobile marketing. Hence mobile marketing for mobile game is an essential key for a mobile game success. Even though there are many articles on marketing for mobile games, there is a need of highly understanding mobile marketing strategies, how to launch a mobile campaign for a mobile game. Besides that, it is essential to understand the relationship between mobile advertising and users behaviours. There...

  3. Satellite-delivered medical education and training for central Europe: a TEMPUS project. Trans-European Mobility Programme for University Students.

    Science.gov (United States)

    Young, H L

    1996-01-01

    This paper reports the experience gained in delivering continuing and postgraduate medical education by satellite to update medical teachers in Central Europe. An infrastructure of receiving sites was established in the Czech Republic, Slovakia, Poland and Hungary. The sites participated in regular, live interactive broadcasts on a range of medical education topics. Over three years a network of sites was established incrementally and a national coordinator identified for each country, who fed back from national coordinating committees to an overall steering body. In the final year a formal evaluation revealed high satisfaction levels and maintenance of activity during the grant period. The major problems related to a lack of telephone lines to facilitate interactivity, the timing of the programmes, and the need for training in medical English language. Video libraries were established, and the majority continued to be active at the end of the project grant. Material was incorporated into both undergraduate and postgraduate education. It is calculated that continuing professional development can be delivered at less than 18 ECU per participant per country.

  4. Satellite RNAs and Satellite Viruses.

    Science.gov (United States)

    Palukaitis, Peter

    2016-03-01

    Satellite RNAs and satellite viruses are extraviral components that can affect either the pathogenicity, the accumulation, or both of their associated viruses while themselves being dependent on the associated viruses as helper viruses for their infection. Most of these satellite RNAs are noncoding RNAs, and in many cases, have been shown to alter the interaction of their helper viruses with their hosts. In only a few cases have the functions of these satellite RNAs in such interactions been studied in detail. In particular, work on the satellite RNAs of Cucumber mosaic virus and Turnip crinkle virus have provided novel insights into RNAs functioning as noncoding RNAs. These effects are described and potential roles for satellite RNAs in the processes involved in symptom intensification or attenuation are discussed. In most cases, models describing these roles involve some aspect of RNA silencing or its suppression, either directly or indirectly involving the particular satellite RNA.

  5. Satellite communications principles and applications

    CERN Document Server

    Calcutt, David

    1994-01-01

    Satellites are increasingly used for global communications, as well as for radio and television transmissions. With the growth of mobile communications, and of digital technology, the use of satellite systems is set to expand substantially and already all students of electronics or communications engineering must study the subject.This book steers a middle path between offering a basic understanding of the process of communication by satellite and the methodology used; and the extensive mathematical analysis normally adopted in similar texts. It presents the basic concepts, using as mu

  6. Mobile radio channels

    CERN Document Server

    Pätzold, Matthias

    2011-01-01

    Providing a comprehensive overview of the modelling, analysis and simulation of mobile radio channels, this book gives a detailed understanding of fundamental issues and examines state-of-the-art techniques in mobile radio channel modelling. It analyses several mobile fading channels, including terrestrial and satellite flat-fading channels, various types of wideband channels and advanced MIMO channels, providing a fundamental understanding of the issues currently being investigated in the field. Important classes of narrowband, wideband, and space-time wireless channels are explored in deta

  7. Sky alert! when satellites fail

    CERN Document Server

    Johnson, Les

    2013-01-01

    How much do we depend on space satellites? Defense, travel, agriculture, weather forecasting, mobile phones and broadband, commerce...the list seems endless. But what would our live be like if the unimaginable happened and, by accident or design, those space assets disappeared? Sky Alert! explores what our world would be like, looking in turn at areas where the loss could have catastrophic effects. The book - demonstrates our dependence on space technology and satellites; - outlines the effect on our economy, defense, and daily lives if satellites and orbiting spacecraft were destroyed; - illustrates the danger of dead satellites, spent rocket stages, and space debris colliding with a functioning satellites; - demonstrates the threat of dramatically increased radiation levels associated with geomagnetic storms; - introduces space as a potential area of conflict between nations.

  8. Centriolar satellites

    DEFF Research Database (Denmark)

    Tollenaere, Maxim A X; Mailand, Niels; Bekker-Jensen, Simon

    2015-01-01

    Centriolar satellites are small, microscopically visible granules that cluster around centrosomes. These structures, which contain numerous proteins directly involved in centrosome maintenance, ciliogenesis, and neurogenesis, have traditionally been viewed as vehicles for protein trafficking...... highlight newly discovered regulatory mechanisms targeting centriolar satellites and their functional status, and we discuss how defects in centriolar satellite components are intimately linked to a wide spectrum of human diseases....

  9. Satellite theory

    Science.gov (United States)

    Kozai, Y.

    1981-04-01

    The dynamical characteristics of the natural satellite of Mars, Jupiter, Saturn, Uranus and Neptune are analyzed on the basis of the solar tidal perturbation factor and the oblateness factor of the primary planet for each satellite. For the inner satellites, for which the value of the solar tidal factor is much smaller than the planetary oblateness factor, it is shown that the eccentricity and inclination of satellite orbits are generally very small and almost constant; several pairs of inner satellites are also found to exhibit commensurable mean motions, or secular accelerations in mean longitude. In the case of the outer satellites, for which solar perturbations are dominant, secular perturbations and long-period perturbations may be derived by the solution of equations of motion reduced to one degree of freedom. The existence of a few satellites, termed intermediary satellites, for which the solar tidal perturbation is on the order of the planetary oblateness factor, is also observed, and the pole of the orbital plane of the satellite is noted to execute a complex motion around the pole of the planet or the orbital plane of the planet.

  10. The Act of Walking

    DEFF Research Database (Denmark)

    Vestergaard, Maria Quvang Harck; Olesen, Mette; Helmer, Pernille Falborg

    2014-01-01

    individuals in Denmark conduct and experience walking, and the ‘rationalities’ (Giddens 1984) that lie behind their choice of mobility. It provides insight into how different lifestyles perceive and act walking in their everyday life. Kaufmann (2002) describes how the individual mobility is influenced......’ of mobility (Jensen 2013:111) such as the urban environment, and the infrastructures. Walking has indeed also a ‘software dimension’ as an embodied performance that trigger the human senses (Jensen 2013) and which is closely related to the habitus and identity of the individual (Halprin 1963). The individual...... by individual strategies, values, perceptions and habits, and how appropriation of mobility is constructed through the internalization of standards and values. The act of walking could thus be understood as the result of dynamic internal negotiation of individual, everyday mobility strategies (Lassen 2005...

  11. Satellite Communications Using Commercial Protocols

    Science.gov (United States)

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

    2000-01-01

    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.

  12. Satellite Communications

    CERN Document Server

    Pelton, Joseph N

    2012-01-01

    The field of satellite communications represents the world's largest space industry. Those who are interested in space need to understand the fundamentals of satellite communications, its technology, operation, business, economic, and regulatory aspects. This book explains all this along with key insights into the field's future growth trends and current strategic challenges. Fundamentals of Satellite Communications is a concise book that gives all of the key facts and figures as well as a strategic view of where this dynamic industry is going. Author Joseph N. Pelton, PhD, former Dean of the International Space University and former Director of Strategic Policy at Intelstat, presents a r

  13. Satellite Geomagnetism

    DEFF Research Database (Denmark)

    Olsen, Nils; Stolle, Claudia

    2012-01-01

    Observations of Earth’s magnetic field from space began more than 50 years ago. A continuous monitoring of the field using low Earth orbit (LEO) satellites, however, started only in 1999, and three satellites have taken highprecision measurements of the geomagnetic field during the past decade...... ability to characterize and understand the many sources that contribute to Earth’s magnetic field. In this review, we summarize investigations of Earth’s interior and environment that have been possible through the analysis of high-precision magnetic field observations taken by LEO satellites........ The unprecedented time-space coverage of their data opened revolutionary new possibilities for monitoring, understanding, and exploring Earth’s magnetic field. In the near future, the three-satellite constellation Swarm will ensure continuity of such measurement and provide enhanced possibilities to improve our...

  14. Satellite (Natural)

    Science.gov (United States)

    Murdin, P.

    2000-11-01

    In its most general sense, any celestial object in orbit around a similar larger object. Thus, for example, the Magellanic Clouds are satellite galaxies of our own Milky Way galaxy. Without qualification, the term is used to mean a body in orbit around a planet; an alternative term is moon. The term natural satellite distinguishes these bodies from artificial satellites—spacecraft placed in orbi...

  15. Signal processing for mobile communications handbook

    CERN Document Server

    Ibnkahla, Mohamed

    2004-01-01

    INTRODUCTIONSignal Processing for Future Mobile Communications Systems: Challenges and Perspectives; Quazi Mehbubar Rahman and Mohamed IbnkahlaCHANNEL MODELING AND ESTIMATIONMultipath Propagation Models for Broadband Wireless Systems; Andreas F. Molisch and Fredrik TufvessonModeling and Estimation of Mobile Channels; Jitendra K. TugnaitMobile Satellite Channels: Statistical Models and Performance Analysis; Giovanni E. Corazza, Alessandro Vanelli-Coralli, Raffaella Pedone, and Massimo NeriMobile Velocity Estimation for Wireless Communications; Bouchra Senadji, Ghazem Azemi, and Boualem Boashash

  16. Technology for a quasi-GSO satellite communications system

    OpenAIRE

    Katagi, T.; Yonezawa, R.; Chiba, I.; Urasaki, S.

    1999-01-01

    In this paper, a satellite communications system using a Quasi Geostationary Satellite Orbit (Quasi-GSO) is proposed. A 24-hour period Quasi-GSO system could give high quality communication to high latitude regions with its satellites observed from earth stations having high elevation angles. In this paper, a system concept and a deployable flat antenna with light weight antenna elements are described proposing it to be a good candidate for mobile communications satellite use.

  17. Mobile agents basic concepts, mobility models, and the tracy toolkit

    CERN Document Server

    Braun, Peter

    2005-01-01

    Mobile agents are software nomads that act as your personal representative, working autonomously through networks. They are able to visit network nodes directly using available computing power and are not limited by platform. This emerging field is now poised to become a cornerstone for new Web-based ubiquitous computing environments. Mobile Agents provides a practical introduction to mobile agent technology and surveys the state of the art in mobile agent research. Students and researchers can use the book as an introduction to the concepts and possibilities of this field and as an overview of ongoing research. Developers can use it to identify the capabilities of the technology to decide if mobile agents are the right solution for them. Practioners can also gain hands-on experience in programming mobile agents through exploration of the source code for a complete mobile agent environment available through the companion website.*Summarizes the state of the art in mobile agent research*Identifies the benefits...

  18. Development and Future of Typical Foreign GEO Satellite Mobile Communication Systems%卫星通信新技术专题讲座(一)第2讲国外典型GEO卫星移动通信系统发展概况及展望

    Institute of Scientific and Technical Information of China (English)

    陈锋; 郭道省; 杨龙

    2012-01-01

    GEO satellite communication system is one of the most important development field for its steady attitude, large coverage area, little Dopplershift, nature techniques and simple operation et al. Several advanced GEO satellite mobile communication systems, including In- marsat, Thuraya, Terrastar and Skyterra, and their characters and developing trends were de- tailedly introduced in this paper. The current development and the future trend of domestic GEO satellite mobile communication systems were also briefly described.%GEO卫星星体相对固定、覆盖面积大、多普勒频移小、技术相对成熟简单,是重要的卫星发展领域之一。文章重点介绍目前国际上比较先进的GEO卫星移动通信系统:Inmarsat、Thuraya、Terrastar和Skyterra,包括这些系统的特点和发展趋势,最后对我国GEO卫星移动通信系统的发展和趋势进行简单的描述。

  19. Mobile Learning Using Mobile Phones

    Science.gov (United States)

    Vicente, Paula

    2013-01-01

    The participation in mobile learning programs is conditioned by having/using mobile communication technology. Those who do not have or use such technology cannot participate in mobile learning programs. This study evaluates who are the most likely participants of mobile learning programs by examining the demographic profile and mobile phone usage…

  20. Advanced ISDN satellite designs and experiments

    Science.gov (United States)

    Pepin, Gerard R.

    1992-01-01

    The research performed by GTE Government Systems and the University of Colorado in support of the NASA Satellite Communications Applications Research (SCAR) Program is summarized. Two levels of research were undertaken. The first dealt with providing interim services Integrated Services Digital Network (ISDN) satellite (ISIS) capabilities that accented basic rate ISDN with a ground control similar to that of the Advanced Communications Technology Satellite (ACTS). The ISIS Network Model development represents satellite systems like the ACTS orbiting switch. The ultimate aim is to move these ACTS ground control functions on-board the next generation of ISDN communications satellite to provide full-service ISDN satellite (FSIS) capabilities. The technical and operational parameters for the advanced ISDN communications satellite design are obtainable from the simulation of ISIS and FSIS engineering software models of the major subsystems of the ISDN communications satellite architecture. Discrete event simulation experiments would generate data for analysis against NASA SCAR performance measure and the data obtained from the ISDN satellite terminal adapter hardware (ISTA) experiments, also developed in the program. The Basic and Option 1 phases of the program are also described and include the following: literature search, traffic mode, network model, scenario specifications, performance measures definitions, hardware experiment design, hardware experiment development, simulator design, and simulator development.

  1. Scientific Satellites

    Science.gov (United States)

    1967-01-01

    followed Hale’s into orbit. In 1879, Jules Verne wrote about launching small satellites with a gun possessing a muzzle velocity of 10 000 m/sec (ref. 3...was activated in 1950.11 It was located only a few tens of miles from the spot where Jules Verne had his Baltimore Gun Club fire a manned projectile to...principle, satellites can be launched by a single impulse applied at the Earth’s surface-say, with a large cannon, & la Jules Verne (sec. 8-3). In

  2. Structural System Design of Mobile Satellite Communication System Vehicular Station Based on SUV Platform%某SUV平台动中通结构总体设计探讨

    Institute of Scientific and Technical Information of China (English)

    白旭东

    2011-01-01

    介绍了某运动型多功能车(Sport Utility Vehicle,SUV)平台动中通的结构总体设计。针对SUV平台的特点,结合系统使用要求,选择了中轮廓动中通天线和取力发电的供电方式,通过对设备分类布局来提高空间利用率的方法解决了载车空间小、上装设备多的问题。从人机工程的角度探讨了在行驶状态下操作的舒适性,并给出了设备机架的限制高度。阐述了上装设备采取的抗振设计考虑。对系统的整车载荷及行驶稳定性进行了分析计算。在满足系统使用要求的同时保持了原车的优越性能,使载车完整性、安全性、可靠性和舒适性最大化,实现了人机环境的和谐。%This paper introduces the structural system design of a mobile satellite communication system vehicular station based on SUV platform.According to the characteristics of SUV platform and the using requirements of system,medium contour antenna and engine driven generator system are selected.The problem of"many facilities in small space" is well solved through classifying facilities to improve space using efficiency.From the viewpoint of ergonomics,operating comfortableness under running condition is discussed and the height limit of rack is presented.Furthermore,the anti-vibration design of facilities are described,the traveling stability and the load of vehicular station are analyzed and calculated.The design retains the superior performance of SUV while satisfying the system requirements,thus maximizing the integrity,safety,reliability,comfortableness of the vehicle,realizing a harmonious human-machine environment.

  3. Interim Service ISDN Satellite (ISIS) simulator development for advanced satellite designs and experiments

    Science.gov (United States)

    Pepin, Gerard R.

    1992-01-01

    The simulation development associated with the network models of both the Interim Service Integrated Services Digital Network (ISDN) Satellite (ISIS) and the Full Service ISDN Satellite (FSIS) architectures is documented. The ISIS Network Model design represents satellite systems like the Advanced Communications Technology Satellite (ACTS) orbiting switch. The FSIS architecture, the ultimate aim of this element of the Satellite Communications Applications Research (SCAR) Program, moves all control and switching functions on-board the next generation ISDN communications satellite. The technical and operational parameters for the advanced ISDN communications satellite design will be obtained from the simulation of ISIS and FSIS engineering software models for their major subsystems. Discrete event simulation experiments will be performed with these models using various traffic scenarios, design parameters, and operational procedures. The data from these simulations will be used to determine the engineering parameters for the advanced ISDN communications satellite.

  4. Mobile User Objective System (MUOS)

    Science.gov (United States)

    2015-12-01

    Objective System (MUOS) is a narrowband Military Satellite Communications (MILSATCOM) system that supports a worldwide, multi -Service population of mobile...with the State Department and the Secretary of Defense regarding the Italian court-issued Niscemi work sequestration. The program entered Multi ...Selected Acquisition Report (SAR) RCS: DD-A&T(Q&A)823-345 Mobile User Objective System (MUOS) As of FY 2017 President’s Budget Defense Acquisition

  5. Mobility management in mobile IP

    Science.gov (United States)

    Medidi, Sirisha; Golshani, Forouzan

    2002-07-01

    There is an emerging interest in integrating mobile wireless communication with the Internet based on the Ipv6 technology. Many issues introduced by the mobility of users arise when such an integration is attempted. This paper addresses the problem of mobility management, i.e., that of tracking the current IP addresses of mobile terminals and sustaining active IP connections as mobiles move. The paper presents some architectural and mobility management options for integrating wireless access to the Internet. We then present performance results for Mobile IPv4, route optimization and Mobile IPv6.

  6. Demonstration on the indexes design of gravity satellite orbit parameters in the low-low satellite-to-satellite tracking mode

    Directory of Open Access Journals (Sweden)

    Liu Xiaogang

    2013-02-01

    Full Text Available Combining with the exigent demand of the development of satellite gravimetry system in China, aiming at the determination of technical indexes of gravity satellite orbit parameters, on the basis of the numerical experiments and results analysis, the design indexes of gravity satellite orbit height, inter-satellite range and the orbit inclination are analyzed and calculated, and the issues towards twin gravity satellites such as coherence requirement of the orbit semi-major axes, control requirement of the pitch angle and time interval requirement to keep twin satellites formation in mobility are discussed. Results show that the satellite orbit height is 400 km to 500 km, the inter-satellite range is about 220 km, the satellite orbit inclination is between polar orbit and sun-synchronous orbit, the semi-major axes difference of twin satellites orbit is within ±70. 146 m, the pitch angle of twin satellites is about 0.9 degree, and the time interval to keep twin satellites formation in mobility is 7 days to 15 days.

  7. ST–ACTS

    DEFF Research Database (Denmark)

    Gidofalvi, Gyozo; Pedersen, Torben Bach

    2006-01-01

    various geo–statistical data sources and intuitive principles, models the so far neglected aspects. ST–ACTS considers that (1) objects (representing mobile users) move from one spatio–temporal location to another with the objective of performing a certain activity at the latter location; (2) not all users...

  8. Mobilities Design

    DEFF Research Database (Denmark)

    Jensen, Ole B.; Lanng, Ditte Bendix

    that of ‘mobilities design’. The book revolves around the following research question: How are design decisions and interventions staging mobilities? It builds upon the Staging Mobilities model (Jensen 2013) in an explorative inquiry into the problems and potentials of the design of mobilities. The exchange value...... between mobilities and design research is twofold. To mobilities research this means getting closer to the ‘material’, and to engage in the creative, explorative and experimental approaches of the design world which offer new potentials for innovative research. Design research, on the other hand, might...... enter into a fruitful relationship with mobilities research, offering a relational and mobile design thinking and a valuable base for a reflective design practice around the ubiquitous structures, spaces and systems of mobilities....

  9. Is There a Mobile Social Presence?

    Science.gov (United States)

    Tu, Chih-Hsiung; McIsaac, Marina; Sujo-Montes, Laura; Armfield, Shadow

    2012-01-01

    Mobile learning environments are human networks that afford the opportunity to participate in creative endeavors, social networking, organize/reorganize social contents, and manage social acts at anytime, anywhere through mobile technologies. Social acts that elicit identities, develop awareness, cement relationships, ensure connections, and…

  10. Is There a Mobile Social Presence?

    Science.gov (United States)

    Tu, Chih-Hsiung; McIsaac, Marina; Sujo-Montes, Laura; Armfield, Shadow

    2012-01-01

    Mobile learning environments are human networks that afford the opportunity to participate in creative endeavors, social networking, organize/reorganize social contents, and manage social acts at anytime, anywhere through mobile technologies. Social acts that elicit identities, develop awareness, cement relationships, ensure connections, and…

  11. Satellite ATM Networks: Architectures and Guidelines Developed

    Science.gov (United States)

    vonDeak, Thomas C.; Yegendu, Ferit

    1999-01-01

    An important element of satellite-supported asynchronous transfer mode (ATM) networking will involve support for the routing and rerouting of active connections. Work published under the auspices of the Telecommunications Industry Association (http://www.tiaonline.org), describes basic architectures and routing protocol issues for satellite ATM (SATATM) networks. The architectures and issues identified will serve as a basis for further development of technical specifications for these SATATM networks. Three ATM network architectures for bent pipe satellites and three ATM network architectures for satellites with onboard ATM switches were developed. The architectures differ from one another in terms of required level of mobility, supported data rates, supported terrestrial interfaces, and onboard processing and switching requirements. The documentation addresses low-, middle-, and geosynchronous-Earth-orbit satellite configurations. The satellite environment may require real-time routing to support the mobility of end devices and nodes of the ATM network itself. This requires the network to be able to reroute active circuits in real time. In addition to supporting mobility, rerouting can also be used to (1) optimize network routing, (2) respond to changing quality-of-service requirements, and (3) provide a fault tolerance mechanism. Traffic management and control functions are necessary in ATM to ensure that the quality-of-service requirements associated with each connection are not violated and also to provide flow and congestion control functions. Functions related to traffic management were identified and described. Most of these traffic management functions will be supported by on-ground ATM switches, but in a hybrid terrestrial-satellite ATM network, some of the traffic management functions may have to be supported by the onboard satellite ATM switch. Future work is planned to examine the tradeoffs of placing traffic management functions onboard a satellite as

  12. Determination of Chinese mobile SLR sites' coordinates

    Institute of Scientific and Technical Information of China (English)

    FENG Chugang; CAI Wusan; ZHU Yuanlan; YANG Fumin

    2003-01-01

    The geocentric coordinates of three mobile sites including Fangshan inBeijing, Urumqi in the Xinjiang Uygur Autonomous Region and Lhasa in Tibet are determined in the ITRF2000 frame by means of both the global SLR data and the mobile (SLR) data obtained by a mobile satellite laser ranging (SLR) apparatus from Aug. 2000 to Dec. 2001. The results showed that the geometrical performance ofChinese SLR network has been significantly improved.

  13. Low Cost Antennas for Direct Broadcast Satellite Radio

    Science.gov (United States)

    Wu, T. K.; Huang, J.

    1994-01-01

    Two omni-directional and circularly polarized low gain antennas (the crossed drooping dipole and the TM(sub 21) mode circular patch antenna)are developed for direct broadcast satellite radio (DBSR) outdoor mobile terminal applications.

  14. SCADA Application for ACTS Technology

    Science.gov (United States)

    Fairbanks, Barry

    1992-01-01

    The results of a system level study done by Hughes Network Systems for NASA are presented. For the supervisory control and data acquisition (SCADA) application, use of Ka-band spot beam satellite technology associated with NASA's Advanced Communication Technology Satellite (ACTS) offers a reduction in Earth station antenna size and transmitter power that may translate into lower system costs. The approaches taken to determine commercial potential of the system are described.

  15. Application of the advanced communications technology satellite for teleradiology and telemedicine

    Science.gov (United States)

    Stewart, Brent K.; Carter, Stephen J.; Rowberg, Alan H.

    1995-05-01

    The authors have an in-kind grant from NASA to investigate the application of the Advanced Communications Technology Satellite (ACTS) to teleradiology and telemedicine using the JPL developed ACTS Mobile Terminal (AMT) uplink. This experiment involves the transmission of medical imagery (CT, MR, CR, US and digitized radiographs including mammograms), between the ACTS/AMT and the University of Washington. This is accomplished by locating the AMT experiment van in various locations throughout Washington state, Idaho, Montana, Oregon and Hawaii. The medical images are transmitted from the ACTS to the downlink at the NASA Lewis Research Center (LeRC) in Cleveland, Ohio, consisting of AMT equipment and the high burst rate-link evaluation terminal (HBR-LET). These images are then routed from LeRC to the University of Washington School of Medicine (UWSoM) through the Internet and public switched Integrated Serviced Digital Network (ISDN). Once images arrive in the UW Radiology Department, they are reviewed using both video monitor softcopy and laser-printed hardcopy. Compressed video teleconferencing and transmission of real-time ultrasound video between the AMT van and the UWSoM are also tested. Image quality comparisons are made using both subjective diagnostic criteria and quantitative engineering analysis. Evaluation is performed during various weather conditions (including rain to assess rain fade compensation algorithms). Compression techniques also are tested to evaluate their effects on image quality, allowing further evaluation of portable teleradiology/telemedicine at lower data rates and providing useful information for additional applications (e.g., smaller remote units, shipboard, emergency disaster, etc.). The medical images received at the UWSoM over the ACTS are directly evaluated against the original digital images. The project demonstrates that a portable satellite-land connection can provide subspecialty consultation and education for rural and remote

  16. Mobile payment

    CERN Document Server

    Lerner, Thomas

    2013-01-01

    Paying with mobile devices such as mobile phones or smart phones will expand worldwide in the coming years. This development provides opportunities for various industries (banking, telecommunications, credit card business, manufacturers, suppliers, retail) and for consumers.

  17. Mobile Lexicography

    DEFF Research Database (Denmark)

    Køhler Simonsen, Henrik

    2015-01-01

    are already mobile – but lexicography is not yet fully ready for the mobile challenge, mobile users and mobile user situations. The article is based on empirical data from two surveys comprising 10 medical doctors, who were asked to look up five medical substances with the medical dictionary app Medicin...... and that lexicographic innovation is needed. A new type of users, new user situations and new access methods call for new lexicographic solutions, and this article proposes a six-pointed hexagram model, which can be used during dictionary app design to lexicographically calibrate the six dimensions in mobile......Mobile phones are ubiquitous and have completely transformed the way we live, work, learn and conduct our everyday activities. Mobile phones have also changed the way users access lexicographic data. In fact, it can be argued that mobile phones and lexicography are not yet compatible. Modern users...

  18. Mobile Lexicography

    DEFF Research Database (Denmark)

    Køhler Simonsen, Henrik

    2015-01-01

    Mobile phones are ubiquitous and have completely transformed the way we live, work, learn and conduct our everyday activities. Mobile phones have also changed the way users access lexicographic data. In fact, it can be argued that mobile phones and lexicography are not yet compatible. Modern users...... are already mobile – but lexicography is not yet fully ready for the mobile challenge, mobile users and mobile user situations. The article is based on empirical data from two surveys comprising 10 medical doctors, who were asked to look up five medical substances with the medical dictionary app Medicin...... and that lexicographic innovation is needed. A new type of users, new user situations and new access methods call for new lexicographic solutions, and this article proposes a six-pointed hexagram model, which can be used during dictionary app design to lexicographically calibrate the six dimensions in mobile...

  19. The Westinghouse Series 1000 Mobile Phone: Technology and applications

    Science.gov (United States)

    Connelly, Brian

    1993-01-01

    Mobile satellite communications will be popularized by the North American Mobile Satellite (MSAT) system. The success of the overall system is dependent upon the quality of the mobile units. Westinghouse is designing our unit, the Series 1000 Mobile Phone, with the user in mind. The architecture and technology aim at providing optimum performance at a low per unit cost. The features and functions of the Series 1000 Mobile Phone have been defined by potential MSAT users. The latter portion of this paper deals with who those users may be.

  20. Mobile robots

    Energy Technology Data Exchange (ETDEWEB)

    Wolfe, W.J.; Marquina, N.

    1986-01-01

    This book presents papers given at a conference on mobile robots. Topics the conference included are the following: mobility systems for robotic vehicles; detection and control of mobile robot motion by real-time computer vision, obstacle avoidance algorithms for an autonomous land vehicle; hierarchical processor and matched filters for range image processing; asynchronous distributed control system for a mobile robot, and, planning in a hierarchical nested autonomous control system.

  1. Mobile Lexicography

    DEFF Research Database (Denmark)

    Køhler Simonsen, Henrik

    2014-01-01

    Users are already mobile, but the question is to which extent knowledge-based dictionary apps are designed for the mobile user situation. The objective of this article is to analyse the characteristics of the mobile user situation and to look further into the stationary user situation and the mob...

  2. Mobilities Design

    DEFF Research Database (Denmark)

    Lanng, Ditte Bendix; Wind, Simon; Jensen, Ole B.

    2017-01-01

    utilitarian transport from A to B; they constitute a rich societal phenomenon with, for example, social, cultural, sensorial, emotional, and material dimensions. The article proposes two fruitful links between the mobilities turn and the designerly examination of mobilities spaces. First, the mobilities turn...

  3. Subversive Mobilities

    DEFF Research Database (Denmark)

    Thelle, Mikkel

    2013-01-01

    The article approaches mobility through a cultural history of urban conflict. Using a case of “The Copenhagen Trouble,“ a series of riots in the Danish capital around 1900, a space of subversive mobilities is delineated. These turn-of-the-century riots points to a new pattern of mobile gathering...

  4. Gaussian Entanglement Distribution via Satellite

    CERN Document Server

    Hosseinidehaj, Nedasadat

    2014-01-01

    In this work we analyse three quantum communication schemes for the generation of Gaussian entanglement between two ground stations. Communication occurs via a satellite over two independent atmospheric fading channels dominated by turbulence-induced beam wander. In our first scheme the engineering complexity remains largely on the ground transceivers, with the satellite acting simply as a reflector. Although the channel state information of the two atmospheric channels remains unknown in this scheme, the Gaussian entanglement generation between the ground stations can still be determined. On the ground, distillation and Gaussification procedures can be applied, leading to a refined Gaussian entanglement generation rate between the ground stations. We compare the rates produced by this first scheme with two competing schemes in which quantum complexity is added to the satellite, thereby illustrating the trade-off between space-based engineering complexity and the rate of ground-station entanglement generation...

  5. Privacy Act

    Science.gov (United States)

    Learn about the Privacy Act of 1974, the Electronic Government Act of 2002, the Federal Information Security Management Act, and other information about the Environmental Protection Agency maintains its records.

  6. Comparison of the peak resolution and the stationary phase retention between the satellite and the planetary motions using the coil satellite centrifuge with counter-current chromatographic separation of 4-methylumbelliferyl sugar derivatives.

    Science.gov (United States)

    Shinomiya, Kazufusa; Zaima, Kazumasa; Harada, Yukina; Yasue, Miho; Harikai, Naoki; Tokura, Koji; Ito, Yoichiro

    2017-01-20

    -hexane/ethyl acetate/1-butanol/methanol/water system at different volume ratios. In the satellite motion at (ω1, ω2, ω3)=(300, 150, 150rpm), almost constant stationary phase retention was obtained with the lower mobile phase regardless of the hydrophobicity of the solvent system whereas the stationary phase retention varied according to the volume ratio of the two-phase solvent system for the upper mobile phase. However, stable stationary phase retention was observed with either phase used as the mobile phase. In order to analyze the acceleration acting on the coiled column, an acceleration sensor was set on the column holder by displacing the multilayer column. The combination of the rotation speeds at (300, 100, 200rpm) showed double loops in the acceleration track, whereas (300, 150, 150rpm) showed a single loop, and all other combinations showed, complex tracks. The overall results indicate that the satellite motion is seriously affected by the combination of rotation speeds and the hydrophobicity of the two-phase solvent system when the upper phase was used as the mobile phase for separation.

  7. Mobile Semiotics

    DEFF Research Database (Denmark)

    Jensen, Ole B.

    2013-01-01

    This chapter aims to understand the mobile condition of contemporary life with a particular view to the signifying dimension of the environment and its ‘readability’. The chapter explores the potentials of semiotics and its relationship to the new mobilities literature. What takes place...... is a ‘mobile sense making’ where signs and materially situated meanings connect to the moving human body and thus create particular challenges and complexities of making sense of the world. The chapter includes notions of mobility systems and socio-technical networks in order to show how a ‘semiotic layer’ may...... work to afford or restrict mobile practices....

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

    Science.gov (United States)

    DeGaudenzi, Riccardo; Giannetti, Filippo

    1995-01-01

    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.

  9. Mobile Lexicography

    DEFF Research Database (Denmark)

    Køhler Simonsen, Henrik

    2014-01-01

    Users are already mobile, but the question is to which extent knowledge-based dictionary apps are designed for the mobile user situation. The objective of this article is to analyse the characteristics of the mobile user situation and to look further into the stationary user situation...... and the mobile user situation. The analysis is based on an empirical survey involving ten medical doctors and a monolingual app designed to support cognitive lexicographic functions, cf. (Tarp 2006:61-64). In test A the doctors looked up five medical terms while sitting down at a desk and in test B the doctors......:565), and it was found that the information access success of the mobile user situation is lower than that of the stationary user situation, primarily because users navigate in the physical world and in the mobile device at the same time. The data also suggest that the mobile user situation is not fully compatible...

  10. Geostationary Satellite (GOES) Images

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Visible and Infrared satellite imagery taken from radiometer instruments on SMS (ATS) and GOES satellites in geostationary orbit. These satellites produced...

  11. Neptune's small satellites

    Science.gov (United States)

    Thomas, P.

    1992-04-01

    The small satellites of Neptune and other planets discovered during the Voyager 2 mission are discussed in terms of their composition and relationship to the planetary systems. The satellite Proteus is described in terms of its orbit, five other satellites are described, and they are compared to ther small satellites and systems. Neptune's satellites are hypothesized to be related to the ring system, and the satellite Galatea is related to the confinement of the rings.

  12. Semantics in mobile sensing

    CERN Document Server

    Yan, Zhixian

    2014-01-01

    The dramatic progress of smartphone technologies has ushered in a new era of mobile sensing, where traditional wearable on-body sensors are being rapidly superseded by various embedded sensors in our smartphones. For example, a typical smartphone today, has at the very least a GPS, WiFi, Bluetooth, triaxial accelerometer, and gyroscope. Alongside, new accessories are emerging such as proximity, magnetometer, barometer, temperature, and pressure sensors. Even the default microphone can act as an acoustic sensor to track noise exposure for example. These sensors act as a ""lens"" to understand t

  13. Dynamic Mobile IP routers in ad hoc networks

    NARCIS (Netherlands)

    Kock, B.A.; Schmidt, J.R.

    2005-01-01

    This paper describes a concept combining mobile IP and ad hoc routing to create a robust mobile network. In this network all nodes are mobile and globally and locally reachable under the same IP address. Essential for implementing this network are the dynamic mobile IP routers. They act as gateways

  14. Dynamic Mobile IP routers in ad hoc networks

    NARCIS (Netherlands)

    Kock, B.A.; Schmidt, J.R.

    2005-01-01

    This paper describes a concept combining mobile IP and ad hoc routing to create a robust mobile network. In this network all nodes are mobile and globally and locally reachable under the same IP address. Essential for implementing this network are the dynamic mobile IP routers. They act as gateways

  15. Measures for mobility education; Massnahmen der Mobilitaetserziehung

    Energy Technology Data Exchange (ETDEWEB)

    Kohler, S.; Hensel, A.; Kustermann, W.; Karg, G. [Technische Univ. Muenchen (Germany)

    2001-07-01

    Mobility education is a major part of a comprehensive mobility management. It aims at influencing children's knowledge, attitudes and behaviour relating to environment and mobility. It ought to qualify for acting self dependent and environmentally consciously. This is of growing importance since an increasing number of trips to kindergartens and schools are made by car and thereby the automobile dominated mobility socialisation is even strengthened. In order to establish mobility education as a permanent service in mobility management the article gives an overview of the scientific principles of mobility education, specially regarding how mobility education is defined and in which way it is applied. Furthermore a scheme for the description and investigation of the various measures of mobility education is derived and a general schedule for the conception of such measures is developed. (orig.)

  16. Mobilities Design

    DEFF Research Database (Denmark)

    Jensen, Ole B.; Lanng, Ditte Bendix; Wind, Simon

    2016-01-01

    In this paper, we identify the nexus between design (architecture, urban design, service design, etc.) and mobilities as a new and emerging research field. In this paper, we apply a “situational mobilities” perspective and take point of departure in the pragmatist question: “What design decisions...... and interventions affords this particular mobile situation?” The paper presents the contours of an emerging research agenda within mobilities research. The advent of “mobilities design” as an emerging research field points towards a critical interest in the material as well as practical consequences of contemporary...... sites of mobilities and technology. Furthermore, the paper argues that heightened material sensitivity with an acute focus on situations and the multi-sensorial dimensions of human mobilities is largely under-prioritised within much contemporary city planning and transport planning as well as policy...

  17. Designing Mobilities

    DEFF Research Database (Denmark)

    Jensen, Ole B.

    of departure in the sociological perspective termed ‘Staging Mobilities’ (Jensen 2013a) and utilizes this as an analytical frame for exploring cases of mobility design. The paper put focus on how the material shape, design and architectures of technologies, spaces and sites influence mobilities practices......, mobilitiy technologies or urban sites of movement we get much closer to understanding the meaning of mobilities to social interaction and culture. The cases are still representing work-in-progress but will be reported in the book ‘Designing Mobilites’ (Jensen 2013b) and will cover the four cases of......Within the so-called ‘mobilities turn’ (Adey 2010; Cresswell 2006; Urry 2007) much research has taken place during the last decade bringing mobilities into the centre of sociological analysis. However, the materiality and spatiality of artefacts, infrastructures, and sites hosting mobilities...

  18. Mobilities Design

    DEFF Research Database (Denmark)

    Jensen, Ole B.; Lanng, Ditte Bendix; Wind, Simon

    2016-01-01

    In this paper, we identify the nexus between design (architecture, urban design, service design, etc.) and mobilities as a new and emerging research field. In this paper, we apply a “situational mobilities” perspective and take point of departure in the pragmatist question: “What design decisions...... and interventions affords this particular mobile situation?” The paper presents the contours of an emerging research agenda within mobilities research. The advent of “mobilities design” as an emerging research field points towards a critical interest in the material as well as practical consequences of contemporary......-making. The paper proposes that increased understanding of the material affordances facilitated through design provides important insight to planning and policymaking that at times might be in risk of becoming too detached from the everyday life of the mobile subject within contemporary mobilities landscapes....

  19. Mobile Semiotics

    DEFF Research Database (Denmark)

    Jensen, Ole B.

    2013-01-01

    This chapter aims to understand the mobile condition of contemporary life with a particular view to the signifying dimension of the environment and its ‘readability’. The chapter explores the potentials of semiotics and its relationship to the new mobilities literature. What takes place is a ‘mob......This chapter aims to understand the mobile condition of contemporary life with a particular view to the signifying dimension of the environment and its ‘readability’. The chapter explores the potentials of semiotics and its relationship to the new mobilities literature. What takes place...... is a ‘mobile sense making’ where signs and materially situated meanings connect to the moving human body and thus create particular challenges and complexities of making sense of the world. The chapter includes notions of mobility systems and socio-technical networks in order to show how a ‘semiotic layer’ may...

  20. Designing Mobilities

    DEFF Research Database (Denmark)

    Jensen, Ole B.

    , mobilitiy technologies or urban sites of movement we get much closer to understanding the meaning of mobilities to social interaction and culture. The cases are still representing work-in-progress but will be reported in the book ‘Designing Mobilites’ (Jensen 2013b) and will cover the four cases of......Within the so-called ‘mobilities turn’ (Adey 2010; Cresswell 2006; Urry 2007) much research has taken place during the last decade bringing mobilities into the centre of sociological analysis. However, the materiality and spatiality of artefacts, infrastructures, and sites hosting mobilities...... of departure in the sociological perspective termed ‘Staging Mobilities’ (Jensen 2013a) and utilizes this as an analytical frame for exploring cases of mobility design. The paper put focus on how the material shape, design and architectures of technologies, spaces and sites influence mobilities practices...

  1. Mobile Clouds

    DEFF Research Database (Denmark)

    Fitzek, Frank; Katz, Marcos

    users in very different ways and for various purposes. The book provides many stimulating examples of resource-sharing applications. Enabling technologies for mobile clouds are also discussed, highlighting the key role of network coding. Mobile clouds have the potential to enhance communications...... of resource sharing takes a wider and deeper meaning, creating the foundations for a global real-time multidimensional resource pool, the underlying infrastructure for shareconomy. Above all, this is an inspiring book for anyone who is concerned about the future of wireless and mobile communications networks...... and their relationship with Social networks. Key Features: Provides fundamental ideas and promising concepts for exploiting opportunistic cooperation and cognition in wireless and mobile networks Gives clear definitions of mobile clouds from different perspectives Associates mobile and wireless networks with social...

  2. Mobility Work

    DEFF Research Database (Denmark)

    Bardram, Jakob Eyvind; Bossen, Claus

    2005-01-01

    We posit the concept of Mobility Work to describe efforts of moving about people and things as part of accomplishing tasks. Mobility work can be seen as a spatial parallel to the concept of articulation work proposed by the sociologist Anselm Strauss. Articulation work describes efforts...... of coordination necessary in cooperative work, but focuses, we argue, mainly on the temporal aspects of cooperative work. As a supplement, the concept of mobility work focuses on the spatial aspects of cooperative work. Whereas actors seek to diminish the amount of articulation work needed in collaboration...... by constructing Standard Operation Procedures (SOPs), actors minimise mobility work by constructing Standard Operation Configurations (SOCs). We apply the concept of mobility work to the ethnography of hospital work, and argue that mobility arises because of the need to get access to people, places, knowledge and...

  3. GOES-R: Satellite Insight

    Science.gov (United States)

    Fitzpatrick, Austin J.; Leon, Nancy J.; Novati, Alexander; Lincoln, Laura K.; Fisher, Diane K.

    2012-01-01

    GOES-R: Satellite Insight seeks to bring awareness of the GOES-R (Geostationary Operational Environmental Satellite -- R Series) satellite currently in development to an audience of all ages on the emerging medium of mobile games. The iPhone app (Satellite Insight) was created for the GOES-R Program. The app describes in simple terms the types of data products that can be produced from GOES-R measurements. The game is easy to learn, yet challenging for all audiences. It includes educational content and a path to further information about GOESR, its technology, and the benefits of the data it collects. The game features action-puzzle game play in which the player must prevent an overflow of data by matching falling blocks that represent different types of GOES-R data. The game adds more different types of data blocks over time, as long as the player can prevent a data overflow condition. Points are awarded for matches, and players can compete with themselves to beat their highest score.

  4. The ACTS multibeam antenna

    Science.gov (United States)

    Regier, Frank A.

    1992-01-01

    The Advanced Communications Technology Satellite (ACTS) to be launched in 1993 is briefly introduced. Its multibeam antenna, consisting of electrically similar 30 GHz receive and 20 GHz transmit offset Cassegrain systems, both utilizing orthogonal polarizations, is described. Dual polarization is achieved by using one feed assembly for each polarization in conjunction with nested front and back subreflectors, the gridded front subreflector acting as a window for one polarization and a reflector for the other. The antennas produce spot beams with approximately 0.3 degree beamwidth and gains of approximately 50 dbi. High surface accuracy and high edge taper produce low sidelobe levels and high cross-polarization isolation. A brief description is given of several Ka-band components fabricated for ACTS. These include multiflare antenna feedhorns, beam-forming networks utilizing latching ferrite waveguide switches, a 30 GHz HEMT low-noise amplifier and a 20 GHz TWT power amplifier.

  5. The ACTS multibeam antenna

    Science.gov (United States)

    Regier, Frank A.

    1992-06-01

    The Advanced Communications Technology Satellite (ACTS) to be launched in 1993 is briefly introduced. Its multibeam antenna, consisting of electrically similar 30 GHz receive and 20 GHz transmit offset Cassegrain systems, both utilizing orthogonal polarizations, is described. Dual polarization is achieved by using one feed assembly for each polarization in conjunction with nested front and back subreflectors, the gridded front subreflector acting as a window for one polarization and a reflector for the other. The antennas produce spot beams with approximately 0.3 degree beamwidth and gains of approximately 50 dbi. High surface accuracy and high edge taper produce low sidelobe levels and high cross-polarization isolation. A brief description is given of several Ka-band components fabricated for ACTS. These include multiflare antenna feedhorns, beam-forming networks utilizing latching ferrite waveguide switches, a 30 GHz HEMT low-noise amplifier and a 20 GHz TWT power amplifier.

  6. Mobility Work

    DEFF Research Database (Denmark)

    Bardram, Jakob Eyvind; Bossen, Claus

    2005-01-01

    by constructing Standard Operation Procedures (SOPs), actors minimise mobility work by constructing Standard Operation Configurations (SOCs). We apply the concept of mobility work to the ethnography of hospital work, and argue that mobility arises because of the need to get access to people, places, knowledge and....../or resources. To accomplish their work, actors have to make the right configuration of these four aspects emerge....

  7. A Time and Space-based Dynamic IP Routing in Broadband Satellite Networks

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    The topology architecture, characteristics and routing technologies of broadband satellite networks are studied in this paper. The authors propose the routing scheme of satellite networks and design a time and space-based distributed routing algorithm whose complexity is O(1). Simulation results aiming at satellite mobility show that the new algorithm can determine the minimum propagation delay paths effectively.

  8. Mobile museology

    DEFF Research Database (Denmark)

    Baggesen, Rikke Haller

    Drawing together perspectives from museology, digital culture studies and fashion theory, this thesis considers changes in and challenges for current - day museums as related to ‘mobile museology’. This concept is developed for and elucidated in the thesis to describe an orientation towards...... the fashionable, the ephemeral, and towards an (ideal) state of change and changeability. This orientation is characterised with the triplet concepts of mobile, mobility, and mobilisation, as related to mobile media and movability; to ‘trans - museal’ mediation; and to the mobilisation of collections, audiences...

  9. Simulator design for advanced ISDN satellite design and experiments

    Science.gov (United States)

    Pepin, Gerald R.

    1992-01-01

    This simulation design task completion report documents the simulation techniques associated with the network models of both the Interim Service ISDN (integrated services digital network) Satellite (ISIS) and the Full Service ISDN Satellite (FSIS) architectures. The ISIS network model design represents satellite systems like the Advanced Communication Technology Satellite (ACTS) orbiting switch. The FSIS architecture, the ultimate aim of this element of the Satellite Communications Applications Research (SCAR) program, moves all control and switching functions on-board the next generation ISDN communication satellite. The technical and operational parameters for the advanced ISDN communications satellite design will be obtained from the simulation of ISIS and FSIS engineering software models for their major subsystems. Discrete events simulation experiments will be performed with these models using various traffic scenarios, design parameters and operational procedures. The data from these simulations will be used to determine the engineering parameters for the advanced ISDN communications satellite.

  10. Monolithic Microwave Integrated Circuit (MMIC) Phased Array Demonstrated With ACTS

    Science.gov (United States)

    1996-01-01

    Monolithic Microwave Integrated Circuit (MMIC) arrays developed by the NASA Lewis Research Center and the Air Force Rome Laboratory were demonstrated in aeronautical terminals and in mobile or fixed Earth terminals linked with NASA's Advanced Communications Technology Satellite (ACTS). Four K/Ka-band experimental arrays were demonstrated between May 1994 and May 1995. Each array had GaAs MMIC devices at each radiating element for electronic beam steering and distributed power amplification. The 30-GHz transmit array used in uplinks to ACTS was developed by Lewis and Texas Instruments. The three 20-GHz receive arrays used in downlinks from ACTS were developed in cooperation with the Air Force Rome Laboratory, taking advantage of existing Air Force integrated-circuit, active-phased-array development contracts with the Boeing Company and Lockheed Martin Corporation. Four demonstrations, each related to an application of high interest to both commercial and Department of Defense organizations, were conducted. The location, type of link, and the data rate achieved for each of the applications is shown. In one demonstration-- an aeronautical terminal experiment called AERO-X--a duplex voice link between an aeronautical terminal on the Lewis Learjet and ACTS was achieved. Two others demonstrated duplex voice links (and in one case, interactive video links as well) between ACTS and an Army high-mobility, multipurpose wheeled vehicle (HMMWV, or "humvee"). In the fourth demonstration, the array was on a fixed mount and was electronically steered toward ACTS. Lewis served as project manager for all demonstrations and as overall system integrator. Lewis engineers developed the array system including a controller for open-loop tracking of ACTS during flight and HMMWV motion, as well as a laptop data display and recording system used in all demonstrations. The Jet Propulsion Laboratory supported the AERO-X program, providing elements of the ACTS Mobile Terminal. The successful

  11. Intelligent Mobility Modeling and Simulation

    Science.gov (United States)

    2015-03-04

    cog.cs.drexel.edu/act-r/index.html) •Models sensory / motor performance of human driver or teleoperator 27UNCLASSIFIED: Distribution Statement A. Approved for...U.S. ARMY TANK AUTOMOTIVE RESEARCH, DEVELOPMENT AND ENGINEERING CENTER Intelligent Mobility Modeling and Simulation 1 Dr. P. Jayakumar, S. Arepally...Prescribed by ANSI Std Z39-18 Contents 1. Mobility - Autonomy - Latency Relationship 2. Machine - Human Partnership 3. Development of Shared Control

  12. Mobile Semiotics - signs and mobilities

    DEFF Research Database (Denmark)

    Jensen, Ole B.

    This paper is about how to comprehend the mobile condition of contemporary life with a particular view to the signifying dimension of the environment and its ‘readability’. The paper explores the potentials of semiotics and its relationship to the new mobilities literature. The theoretical scope...... is therefore an attempt to mobilize semiotics by drawing on a central body of theory within and adjacent to the discipline. For instance the founding works of C. S. Peirce will be related to the contemporary notions of ‘geosemiotics’ by Scollon & Scollon. The paper’s theoretical claim is that semiotics hold...... a potential for mobilities studies if the awareness of seeing the environment as a semiotic layer and system can be sensitized to the insights of the ‘mobilities turn’. Empirically the paper tentatively explores the usefulness of a mobile semiotics approach to cases such as street signage, airport design...

  13. Mobile phones and mobile communication

    DEFF Research Database (Denmark)

    Ling, Richard; Donner, Jonathan

    With staggering swiftness, the mobile phone has become a fixture of daily life in almost every society on earth. In 2007, the world had over 3 billion mobile subscriptions. Prosperous nations boast of having more subscriptions than people. In the developing world, hundreds of millions of people who...... could never afford a landline telephone now have a mobile number of their own. With a mobile in our hand many of us feel safer, more productive, and more connected to loved ones, but perhaps also more distracted and less involved with things happening immediately around us. Written by two leading...... researchers in the field, this volume presents an overview of the mobile telephone as a social and cultural phenomenon. Research is summarized and made accessible though detailed descriptions of ten mobile users from around the world. These illustrate popular debates, as well as deeper social forces at work...

  14. ACTS 2014

    DEFF Research Database (Denmark)

    Co-curator of ACTS 2014 together with Rasmus Holmboe, Judith Schwarzbart and Sanne Kofoed. ACTS is the Museum of Contemporary Art’s international bi-annual festival. ACTS was established in 2011 and, while the primary focus is on sound and performance art, it also looks toward socially oriented art...... various possibilities and public spaces as a stage. ACTS takes place in and around the museum and diverse locations in Roskilde city. ACTS is partly curated by the museum staff and partly by guest curators. ACTS 2014 is supported by Nordea-fonden and is a part of the project The Museum goes downtown....

  15. Mobile contingency unit

    Energy Technology Data Exchange (ETDEWEB)

    Silva, Sergio O. da; Magalhaes, Milton P. de [Petroleo Brasileiro S.A. (PETROBRAS), Rio de Janeiro, RJ (Brazil); Junqueira, Rodrigo A.; Torres, Carlos A.R. [PETROBRAS Transporte S/A (TRANSPETRO), Rio de Janeiro, RJ (Brazil)

    2009-07-01

    This paper is aimed at presenting what is already a reality in TRANSPETRO in the area covered by OSBRA, a pipeline that carries by-products to the Mid-West region of Brazil. In order to meet the needs of covering occasional accidents, TRANSPETRO counts on a standardized system of emergency management. It is a great challenge to secure an efficient communication along the 964 km of extension, considering that there are shadow zones where it is not possible to use conventional means of communication such as mobile telephony and internet. It was in this context that the Mobile Contingency Unit Via Satellite - MCU was developed, to extend the communication facilities existing in fixed installations to remote places, mainly the pipeline right of ways. In case of emergency, simulation and work in the pipeline right of way, MCU is fully able to provide the same data, voice, closed-circuit TV and satellite video conference facilities that are available in any internal area of the PETROBRAS system. (author)

  16. Mobile Clouds

    DEFF Research Database (Denmark)

    Fitzek, Frank; Katz, Marcos

    examples of mobile clouds applications, based on both existing commercial initiatives as well as proof-of-concept test-beds. Visions and prospects are also discussed, paving the way for further development. As mobile networks and social networks become more and more reliant on each other, the concept...

  17. Residential mobility

    DEFF Research Database (Denmark)

    Morris, Tim; Manley, David; Sabel, Clive

    2016-01-01

    lacks the detail and temporal perspectives now seen as critical to understanding residential mobility decisions. Through a critical re-think of mobility processes with respect to health outcomes and an exploitation of longitudinal analytical techniques we argue that health geographers have the potential...

  18. Application of the advanced communications technology satellite to teleradiology and real-time compressed ultrasound video telemedicine.

    Science.gov (United States)

    Stewart, B K; Carter, S J; Cook, J N; Abbe, B S; Pinck, D; Rowberg, A H

    1999-05-01

    The authors have investigated the application of the NASA Advanced Communications Technology Satellite (ACTS) to teleradiology and telemedicine using the Jet Propulsion Laboratory (JPL)-developed ACTS Mobile Terminal (AMT) uplink. In this experiment, bidirectional 128, 256, and 384 kbps satellite links were established between the ACTS/AMT, the ACTS in geosynchronous orbit, and the downlink terrestrial terminal at JPL. A terrestrial Integrated Digital Services Network (ISDN) link was established from JPL to the University of Washington Department of Radiology to complete the bidirectional connection. Ultrasound video imagery was compressed in real-time using video codecs adhering to the International Telecommunication Union-Telecommunication Standardization Sector (ITU-T) Recommendation H.261. A 16 kbps in-band audio channel was used throughout. A five-point Likert scale was used to evaluate the quality of the compressed ultrasound imagery at the three transmission bandwidths (128, 256, and 384 kbps). The central question involved determination of the bandwidth requirements to provide sufficient spatial and contrast resolution for the remote visualization of fine- and low-contrast objects. The 384 kbps bandwidth resulted in only slight tiling artifact and fuzziness owing to the quantizer step size; however, these motion artifacts were rapidly resolved in time at this bandwidth. These experiments have demonstrated that real-time compressed ultrasound video imagery can be transmitted over multiple ISDN line bandwidth links with sufficient temporal, contrast, and spatial resolution for clinical diagnosis of multiple disease and pathology states to provide subspecialty consultation and educational at a distance.

  19. Odyssey, an optimized personal communications satellite system

    Science.gov (United States)

    Rusch, Roger J.

    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

  20. Satellite data compression

    CERN Document Server

    Huang, Bormin

    2011-01-01

    Satellite Data Compression covers recent progress in compression techniques for multispectral, hyperspectral and ultra spectral data. A survey of recent advances in the fields of satellite communications, remote sensing and geographical information systems is included. Satellite Data Compression, contributed by leaders in this field, is the first book available on satellite data compression. It covers onboard compression methodology and hardware developments in several space agencies. Case studies are presented on recent advances in satellite data compression techniques via various prediction-

  1. Trends in communications satellites

    CERN Document Server

    Curtin, Denis J

    1979-01-01

    Trends in Communications Satellites offers a comprehensive look at trends and advances in satellite communications, including experimental ones such as NASA satellites and those jointly developed by France and Germany. The economic aspects of communications satellites are also examined. This book consists of 16 chapters and begins with a discussion on the fundamentals of electrical communications and their application to space communications, including spacecraft, earth stations, and orbit and wavelength utilization. The next section demonstrates how successful commercial satellite communicati

  2. Virtual Network Connection using Mobile Phones

    Directory of Open Access Journals (Sweden)

    Haripriya. S

    2014-06-01

    Full Text Available Mobile cloud computing provides a solution to meet the increasing functionality demands of end -users, as all application logic is executed on distant servers and only user interface functionalities reside on the mobile device. The mobile device acts as a remote display, capturing user input and rendering the display updates received from the distant server. Varying wireless channel conditions, short battery lifetime and interaction latency introduce major challenges for the remote display of cloud applications on mobile devices. In this paper discussed a number of adequate solutions that have recently been proposed to tackle the main issues associated with the re mote display of cloud services on mobile devices.

  3. Virtual Network Connection using Mobile Phones

    Directory of Open Access Journals (Sweden)

    Haripriya. S

    2015-11-01

    Full Text Available Mobile cloud computing provides a solution to meet the increasing functionality demands of end-users, as all application logic is executed on distant servers and only user interface functionalities reside on the mobile device. The mobile device acts as a remote display, capturing user input and rendering the display updates received from the distant server. Varying wireless channel conditions, short battery lifetime and interaction latency introduce major challenges for the remote display of cloud applications on mobile devices. In this paper discussed a number of adequate solutions that have recently been proposed to tackle the main issues associated with the remote display of cloud services on mobile devices.

  4. Antenna technology for advanced mobile communication systems

    Science.gov (United States)

    Rammos, Emmanuel; Roederer, Antoine; Rogard, Roger

    1988-01-01

    The onboard antenna front end is the key subsystem conditioning configuration and performance of mobile communication satellites. The objectives of this paper are to demonstrate this key role and to review L-band satellite antenna technology for earth coverage and regional applications. Multibeam arrays are first discussed, then unfurlable and inflatable reflector antennas are described. These technologies are now qualified in Europe for future mobile systems, for which the optimum choice of antenna technology has been found to be the key to efficient use of spectrum and power resources.

  5. Mobile probes

    DEFF Research Database (Denmark)

    2016-01-01

    A project investigating the effectiveness of a collection of online resources for teachers' professional development used mobile probes as a data collection method. Teachers received questions and tasks on their mobile in a dialogic manner while in their everyday context as opposed to in an inter......A project investigating the effectiveness of a collection of online resources for teachers' professional development used mobile probes as a data collection method. Teachers received questions and tasks on their mobile in a dialogic manner while in their everyday context as opposed...... to in an interview. This method provided valuable insight into the contextual use, i.e. how did the online resource transfer to the work practice. However, the research team also found that mobile probes may provide the scaffolding necessary for individual and peer learning at a very local (intra-school) community...... level. This paper is an initial investigation of how the mobile probes process proved to engage teachers in their efforts to improve teaching. It also highlights some of the barriers emerging when applying mobile probes as a scaffold for learning....

  6. A Context-Aware Mobile Organizer for University Students

    OpenAIRE

    Seyed H. Mirisaee; Abdullah M. Zin

    2009-01-01

    Problem statement: With the expansion of mobile devices, the usage of context-aware mobile applications is becoming very popular. Approach: One of mobile applications that are useful for university students is the university mobile organizer. University Mobile Organizer is a software that acts like an assistant for students in their universities' activities. Results: However, this application was not used widely by the students. In this research, we explored students' problems and requirement...

  7. Mobile Navigation for Sport’s Pilots

    Directory of Open Access Journals (Sweden)

    Dušan Fister

    2013-06-01

    Full Text Available Today, global object-positioning is accomplished very precisely by GPS satellite technology. Access to this information is provided globally by widespread mobile devices with integrated GPS receivers from everywhere also from airplane. This paper presents a mobile device using GPS receiver to be used by mobile navigation for sports pilots. In fact, the mobile navigation is a mobile application running on Android. Thus, the current position of the airplane is indicated on the GoogleMaps and compared with the planned direction of the flight by the pilot. In addition, this mobile application could also serve flight instructors when tracking student pilots by first independent flights. The proposed solution has shown in practice to be the cheapest substitute for expensive professional navigation devices.

  8. Spaceborne Mobile Ad-Hoc Networks

    Science.gov (United States)

    Forcada, Ignasi; Strauss, Adi

    2010-08-01

    Reliable global networking is essential for a rapidly growing mobile and interactive communication. Satellite communication plays already a significant role in this subject. However, the classical space-based data transmission requires an appropriate infrastructure, both on the ground and in orbit. This paper discusses the potential of a self-organising distributed satellite system in Low Earth Orbits (LEO) to achieve a seamless integration in already existing infrastructures. The communication approach is based on dynamic Inter Satellite Links (ISL) not controlled nor coordinated on an individual basis from the ground-based stations.

  9. Feedforward attitude control for a TDRS with mobile antennas

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    In this paper, feedforward attitude control law for a Tracking and Data Relay Satellite (TDRS) with mobile antennas is proposed. To track or point the target spacecraft with median/law orbit, the large mobile antennas have to move in a wide range. The movement of such mobile antennas disturbs the satellite attitude consequently. Conventionally, the main body of the satellite and the mobile antennas are controlled independently.The proposed controller first estimates the angular momentum which the mobile antennas will produce based on the momentum conservation equation. Next, it computes the desired velocity of reaction wheels to compensate the disturbance due to the antenna motion. It then adds the error of the wheels' velocity between a desired one and a current value as a feedforward signal to the control system. The proposed controller is demonstrated using a mathematical simulation, of which these results coincide well with analytical results.

  10. Mobilities Design

    DEFF Research Database (Denmark)

    Jensen, Ole B.; Lanng, Ditte Bendix

    2016-01-01

    of increasing concern and societal importance, regardless if the focus is on new inequalities, environmental sustainability, or the meaning of vernacular mobilities design to the everyday life. The theme of ‘mobilities design’ opens up the agenda of architectural research into infrastructure spaces as ‘spaces...... insights, concepts of space and place, and relations between fixities and flows. The new and emerging field of ‘mobilities design’ will be exploring the borderlines between architecture, urban design, urban planning, and infrastructure design. The field will address the ‘gap’ in research on an issue...... of life’ for billions of people in the everyday life. This paper is structured in three parts. After the general introduction we present the mobilities theory perspective of ‘staging mobilities’ and connects this to the empirical phenomenon of parking lots and their design. The paper ends in section three...

  11. Mobile Learning

    Directory of Open Access Journals (Sweden)

    Anke Petschenka

    2014-03-01

    Full Text Available Rezension zu: de Witt, Claudia, und Almut Sieber, Hrsg. 2013. Mobile Learning: Potenziale, Einsatzszenarien und Perspektiven des Lernens mit mobilen Endgeräten. Wiesbaden: Springer VS.

  12. Designing Mobilities

    DEFF Research Database (Denmark)

    Jensen, Ole B.

    How is the width of the pavement shaping the urban experience? How is the material design of transport infrastructure and mobile technology affording social interaction in everyday life spaces? How do people inhabit these spaces with their bodies and in accordance to social and cultural norms......? These are some of the questions that this book raises in order to explore how the design of mobile sites and situations affect people's everyday life. The book takes point of departure in the author's book 'Staging Mobilities' (Routledge, 2013) in which it is argued that mobility is much more than simple...... movements of people, goods, and information 'from A to B'. Accordingly, the way people, goods, and information moves shapes the way we understand our built environment, other consociates, and ourselves. The book contributes with a new and critical-creative gaze on what might seem to be trivial and mundane...

  13. Restricted Mobilities

    DEFF Research Database (Denmark)

    Nielsen, Mette; Lassen, Claus

    2012-01-01

    communities and shopping centres through mobility lenses. The article shows how different mobility systems enable and restrict the public access to private-public spaces, and it points out that proprietary communities create an unequal potential for human movement and access in the city. The main argument......Privatisation of public spaces in the contemporary city has increased during the last decades but only few studies have approached this field from a mobility perspective. Therefore the article seeks to rectify this by exploring two Australian examples of private spaces in the city; gated...... in the article is that the many mobility systems enable specialization of places that are targeted at a special section of the population. This means that various forms of motilities not only create new opportunities for urban life but it is also one of the most critical components of production of new exclusion...

  14. Mobile museology

    DEFF Research Database (Denmark)

    Baggesen, Rikke Haller

    posts from the research project blog with three research articles: ‘Museum metamorphosis à la mode’, proposing a fashion perspective on ongoing museum developments; ‘Augmenting the agora: media and civic engagement in museums’, questioning the idea of social media holding a vital potential......Drawing together perspectives from museology, digital culture studies and fashion theory, this thesis considers changes in and challenges for current - day museums as related to ‘mobile museology’. This concept is developed for and elucidated in the thesis to describe an orientation towards...... the fashionable, the ephemeral, and towards an (ideal) state of change and changeability. This orientation is characterised with the triplet concepts of mobile, mobility, and mobilisation, as related to mobile media and movability; to ‘trans - museal’ mediation; and to the mobilisation of collections, audiences...

  15. Mobile Commerce

    Directory of Open Access Journals (Sweden)

    Maria Cristina Enache

    2016-07-01

    Full Text Available Mobile commerce, or m-commerce, refers to the use of wireless digital devices to enable transactions on the Web. Described more fully in Chapter 3, m-commerce involves the use of wireless networks to connect cell phones, handheld devices such Blackberries, and personal computers to the Web. Once connected, mobile consumers can conduct transactions, including stock trades, in-store price comparisons, banking, travel reservations, and more.

  16. Xichang Satellite Launch Center

    Institute of Scientific and Technical Information of China (English)

    LiuJie

    2004-01-01

    Xichang Satellite Launch Center(XSLC) is mainly for geosynchronous orbit launches. The main purpose of XSLC is to launch spacecraft, such as broadcasting,communications and meteorological satellites, into geo-stationary orbit.Most of the commercial satellite launches of Long March vehicles have been from Xichang Satellite Launch Center. With 20 years' development,XSLC can launch 5 kinds of launch vehicles and send satellites into geostationary orbit and polar orbit. In the future, moon exploration satellites will also be launched from XSLC.

  17. Handbook of satellite applications

    CERN Document Server

    Madry, Scott; Camacho-Lara, Sergio

    2017-01-01

    The first edition of this ground breaking reference work was the most comprehensive reference source available about the key aspects of the satellite applications field. This updated second edition covers the technology, the markets, applications and regulations related to satellite telecommunications, broadcasting and networking—including civilian and military systems; precise satellite navigation and timing networks (i.e. GPS and others); remote sensing and meteorological satellite systems. Created under the auspices of the International Space University based in France, this brand new edition is now expanded to cover new innovative small satellite constellations, new commercial launching systems, innovation in military application satellites and their acquisition, updated appendices, a useful glossary and more.

  18. Mobility Challenges

    DEFF Research Database (Denmark)

    Jensen, Ole B.; Lassen, Claus

    2011-01-01

    This article takes point of departure in the challenges to understand the importance of contemporary mobility. The approach advocated is a cross-disciplinary one drawing on sociology, geography, urban planning and design, and cultural studies. As such the perspective is to be seen as a part of th...... mobilities. In particular the article discusses 1) the physical city, its infrastructures and technological hardware/software, 2) policies and planning strategies for urban mobility and 3) the lived everyday life in the city and the region.......This article takes point of departure in the challenges to understand the importance of contemporary mobility. The approach advocated is a cross-disciplinary one drawing on sociology, geography, urban planning and design, and cultural studies. As such the perspective is to be seen as a part...... of the so-called ‘mobility turn’ within social science. The perspective is illustrative for the research efforts at the Centre for Mobility and Urban Studies (C-MUS), Aalborg University. The article presents the contours of a theoretical perspective meeting the challenges to research into contemporary urban...

  19. Galileo satellite antenna modeling

    Science.gov (United States)

    Steigenberger, Peter; Dach, Rolf; Prange, Lars; Montenbruck, Oliver

    2015-04-01

    The space segment of the European satellite navigation system Galileo currently consists of six satellites. Four of them belong to the first generation of In-Orbit Validation (IOV) satellites whereas the other two are Full Operational Capability (FOC) satellites. High-precision geodetic applications require detailed knowledge about the actual phase center of the satellite and receiver antenna. The deviation of this actual phase center from a well-defined reference point is described by phase center offsets (PCOs) and phase center variations (PCVs). Unfortunately, no public information is available about the Galileo satellite antenna PCOs and PCVs, neither for the IOV, nor the FOC satellites. Therefore, conventional values for the IOV satellite antenna PCOs have been adopted for the Multi-GNSS experiment (MGEX) of the International GNSS Service (IGS). The effect of the PCVs is currently neglected and no PCOs for the FOC satellites are available yet. To overcome this deficiency in GNSS observation modeling, satellite antenna PCOs and PCVs are estimated for the Galileo IOV satellites based on global GNSS tracking data of the MGEX network and additional stations of the legacy IGS network. Two completely independent solutions are computed with the Bernese and Napeos software packages. The PCO and PCV values of the individual satellites are analyzed and the availability of two different solutions allows for an accuracy assessment. The FOC satellites are built by a different manufacturer and are also equipped with another type of antenna panel compared to the IOV satellites. Signal transmission of the first FOC satellite has started in December 2014 and activation of the second satellite is expected for early 2015. Based on the available observations PCO estimates and, optionally PCVs of the FOC satellites will be presented as well. Finally, the impact of the new antenna model on the precision and accuracy of the Galileo orbit determination is analyzed.

  20. Spatial narratives from mobile GIS

    DEFF Research Database (Denmark)

    Møller-Jensen, Lasse

    2007-01-01

    Principles of a mobile gps-enabled gis acting as a tourist infor­mation sys­tem are discussed and exemplified with special focus on the narrative aspects of tourist guidance. Flexible adaptation to user movements is accomplished by providing information about objects that the user passes as well...

  1. Spatial narratives from mobile GIS

    DEFF Research Database (Denmark)

    Møller-Jensen, Lasse

    2007-01-01

    Principles of a mobile gps-enabled gis acting as a tourist infor­mation sys­tem are discussed and exemplified with special focus on the narrative aspects of tourist guidance. Flexible adaptation to user movements is accomplished by providing information about objects that the user passes as well...

  2. DVB-H vs. DVB-NGH: A survey and comparison for the evolution of mobile TV broadcasting

    CSIR Research Space (South Africa)

    Bembe, M

    2015-07-01

    Full Text Available DVB-NGH (Digital Video Broadcasting-Next Generation Handheld) is the next generation technology for mobile TV broadcasting. It integrates both satellite and terrestrial techniques, which is vital in supporting rich media content for mobile handheld...

  3. 卫星平台虚拟化--满足多种卫星移动通信需求的必然选择%Virtualizing the On-Board Platform for Multi-Purpose Mobile Satellite Communication Systems

    Institute of Scientific and Technical Information of China (English)

    王京; 赵明; 高镇

    2015-01-01

    The market for mobile satel ite communication is huge in China, but satel ite resources are very limited. A key issue in the development of mobile satel ite communication in China is the efficient utilization of the satel ite platform to satisfy the requirements of different military and public applications. Virtualization of the on-board platform is an effective way of addressing this issue. In this paper, we propose a virtualization design based on FFT. This design can be a reference for on research on-board platform virtualization.%认为虽然中国卫星移动通信市场巨大但卫星资源紧缺,因此充分利用有限的卫星平台,最大限度满足不同军民通信应用需求并支持多种传输体制,是中国发展卫星移动通信系统必须要解决的重要问题,而卫星平台虚拟化是解决这个矛盾的有效途径。基于此,提出了一种基于快速傅里叶变换(FFT)的虚拟化设计方案,为推动卫星平台虚拟化研究提供参考。

  4. Satellite-Delivered Learning.

    Science.gov (United States)

    Arnall, Gail C.

    1987-01-01

    Discusses the application of satellite information delivery to training. Describes a new trend, horizontal programming. Also discusses vertical programming and in-house production of training materials. Lists vendors of satellite-based training. (CH)

  5. GPS Satellite Simulation Facility

    Data.gov (United States)

    Federal Laboratory Consortium — The GPS satellite simulation facility consists of a GPS satellite simulator controlled by either a Silicon Graphics Origin 2000 or PC depending upon unit under test...

  6. China's Recoverable Satellites

    Institute of Scientific and Technical Information of China (English)

    Tang Boehang

    2008-01-01

    @@ By the end of 2006, China had launched 24 recoverable satellites (FSW) in total. Among them, 23 were launched successfully, of which all but one were successfully recovered. Recoverable satellites launched by China are listed in Table 1.

  7. Satellite Tags- Hawaii EEZ

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Satellite tagging was implemented in 2013. Satellite tagging is conducted using a Dan Inject air rifle and deployment arrows designed by Wildlife Computers. Two...

  8. Satellite communication engineering

    CERN Document Server

    Kolawole, Michael Olorunfunmi

    2013-01-01

    An undeniably rich and thorough guide to satellite communication engineering, Satellite Communication Engineering, Second Edition presents the fundamentals of information communications systems in a simple and succinct way. This book considers both the engineering aspects of satellite systems as well as the practical issues in the broad field of information transmission. Implementing concepts developed on an intuitive, physical basis and utilizing a combination of applications and performance curves, this book starts off with a progressive foundation in satellite technology, and then moves on

  9. A direct broadcast satellite-audio experiment

    Science.gov (United States)

    Vaisnys, Arvydas; Abbe, Brian; Motamedi, Masoud

    1992-03-01

    System studies have been carried out over the past three years at the Jet Propulsion Laboratory (JPL) on digital audio broadcasting (DAB) via satellite. The thrust of the work to date has been on designing power and bandwidth efficient systems capable of providing reliable service to fixed, mobile, and portable radios. It is very difficult to predict performance in an environment which produces random periods of signal blockage, such as encountered in mobile reception where a vehicle can quickly move from one type of terrain to another. For this reason, some signal blockage mitigation techniques were built into an experimental DAB system and a satellite experiment was conducted to obtain both qualitative and quantitative measures of performance in a range of reception environments. This paper presents results from the experiment and some conclusions on the effectiveness of these blockage mitigation techniques.

  10. Intensive mobilities:

    DEFF Research Database (Denmark)

    Vannini, Phillip; Bissell, David; Jensen, Ole B.

    This paper explores the intensities of long distance commuting journeys as a way of exploring how bodily sensibilities are being changed by the mobilities that they undertake. The context of this paper is that many people are travelling further to work than ever before owing to a variety of facto....... By exploring how experiences of long-distance workers become constituted by a range of different material forces enables us to more sensitively consider the practical, technical, and political implications of this increasingly prevalent yet underexplored regime of work....... which relate to transport, housing and employment. Yet we argue that the experiential dimensions of long distance mobilities have not received the attention that they deserve within geographical research on mobilities. This paper combines ideas from mobilities research and contemporary social theory...... with fieldwork conducted in Canada, Denmark and Australia to develop our understanding of the experiential politics of long distance workers. Rather than focusing on the extensive dimensions of mobilities that are implicated in patterns and trends, our paper turns to the intensive dimensions of this experience...

  11. Mobile healthcare.

    Science.gov (United States)

    Morgan, Stephen A; Agee, Nancy Howell

    2012-01-01

    Mobile technology's presence in healthcare has exploded over the past five years. The increased use of mobile devices by all segments of the US population has driven healthcare systems, providers, and payers to accept this new form of communication and to develop strategies to implement and leverage the use of mobile healthcare (mHealth) within their organizations and practices. As healthcare systems move toward a more value-driven model of care, patient centeredness and engagement are the keys to success. Mobile healthcare will provide the medium to allow patients to participate more in their care. Financially, mHealth brings to providers the ability to improve efficiency and deliver savings to both them and the healthcare consumer. However, mHealth is not without challenges. Healthcare IT departments have been reluctant to embrace this shift in technology without fully addressing security and privacy concerns. Providers have been hesitant to adopt mHealth as a form of communication with patients because it breaks with traditional models. Our healthcare system has just started the journey toward the development of mHealth. We offer an overview of the mobile healthcare environment and our approach to solving the challenges it brings to healthcare organizations.

  12. Taiyuan Satellite Launch Center

    Institute of Scientific and Technical Information of China (English)

    LiuJie

    2004-01-01

    There are three major space launch bases in China, the Jiuquan Satellite Launch Center,the Taiyuan Satellite Launch Center and the Xichang Satellite Launch Center. All the three launch centers are located in sparsely populated areas where the terrain is even and the field of vision is broad. Security, transport conditions and the influence of the axial rotation

  13. Geodetic Secor Satellite

    Science.gov (United States)

    1974-06-01

    simple, and had low-power lem. 17 14. Satellite Orientation . The satellite was designed to maintain a constant relationship between the antenna...the same satellite orientation . Further considerations were Th oscillations, however, when higher orbital ranges (500-2500 nautical miles) -, 3 a

  14. TC-2 Satellite Delivered

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    On April 18, 2005, TC-2, the second satellite of Double Star Program (DSP), which was jointly developed by CNSA and ESA, was approved to be delivered to the user after the on-board test and trial operation. The satellite is working well and the performance can meet the user's need. The satellite has collected large amount of valuable scientific data

  15. 78 FR 78257 - Verification of Statements of Account Submitted by Cable Operators and Satellite Carriers

    Science.gov (United States)

    2013-12-26

    ... Satellite Carriers AGENCY: U.S. Copyright Office, Library of Congress. ACTION: Interim rule. SUMMARY: The U... Satellite Television Extension and Localism Act of 2010 (``STELA''). Cable operators and satellite carriers... regulations to allow copyright owners to audit the SOAs and royalty fees that cable operators and...

  16. Cellular Satellites: Joint Communications With Integrated Acquisition

    Science.gov (United States)

    2015-04-01

    PEO C3T). He has an master’s degree in Business Management from Oklahoma City University, a master’s in National Resource Strategy from the...battlespace.This progress is possible due to the Mobile User Objective System (MUOS), the next-generation narrowband military satellite communication system that...nodes in extreme latitudes. Other demonstrations continue, including assessments of communications perfor- mance with different applications and

  17. Mobile Router Developed and Tested

    Science.gov (United States)

    Ivancic, William D.

    2002-01-01

    The NASA Glenn Research Center, under a NASA Space Act Agreement with Cisco Systems, has been performing joint networking research to apply Internet-based technologies and protocols to space-based communications. As a result of this research, NASA performed stringent performance testing of the mobile router, including the interaction of routing and the transport-level protocol. In addition, Cisco Systems developed the mobile router for both commercial and Government markets. The code has become part of the Cisco Systems Internetworking Operating System (IOS) as of release 12.2 (4) T--which will make this capability available to the community at large. The mobile router is software code that resides in a network router and enables entire networks to roam while maintaining connectivity to the Internet. This router code is pertinent to a myriad of applications for both Government and commercial sectors, including the "wireless battlefield." NASA and the Department of Defense will utilize this technology for near-planetary observation and sensing spacecraft. It is also a key enabling technology for aviation-based information applications. Mobile routing will make it possible for information such as weather, air traffic control, voice, and video to be transmitted to aircraft using Internet-based protocols. This technology shows great promise in reducing congested airways and mitigating aviation disasters due to bad weather. The mobile router can also be incorporated into emergency vehicles (such as ambulances and life-flight aircraft) to provide real-time connectivity back to the hospital and health-care experts, enabling the timely application of emergency care. Commercial applications include entertainment services, Internet protocol (IP) telephone, and Internet connectivity for cruise ships, commercial shipping, tour buses, aircraft, and eventually cars. A mobile router, which is based on mobile IP, allows hosts (mobile nodes) to seamlessly "roam" among various IP

  18. The Act of Walking

    DEFF Research Database (Denmark)

    Vestergaard, Maria Quvang Harck; Olesen, Mette; Helmer, Pernille Falborg

    2014-01-01

    ’ of mobility (Jensen 2013:111) such as the urban environment, and the infrastructures. Walking has indeed also a ‘software dimension’ as an embodied performance that trigger the human senses (Jensen 2013) and which is closely related to the habitus and identity of the individual (Halprin 1963). The individual...... the individuals evaluate, interpret and act (Bourdieu 1984), and how this affects their choice to walk. Therefore it could be questioned if whether an assessment of the physical environment is sufficient to identify all the factors that influence the individual perception of ‘walkability’, or if other influencing...

  19. 78 FR 39200 - Federal Earth Stations-Non-Federal Fixed Satellite Service Space Stations; Spectrum for Non...

    Science.gov (United States)

    2013-07-01

    ...-11341; FCC 13-65] Federal Earth Stations--Non-Federal Fixed Satellite Service Space Stations; Spectrum... interference protection for Fixed-Satellite Service (FSS) and Mobile- Satellite Service (MSS) earth stations... and the important role it will play in our nation's economy and technological innovation now and in...

  20. Mobile Agents

    Science.gov (United States)

    Satoh, Ichiro

    Mobile agents are autonomous programs that can travel from computer to computer in a network, at times and to places of their own choosing. The state of the running program is saved, by being transmitted to the destination. The program is resumed at the destination continuing its processing with the saved state. They can provide a convenient, efficient, and robust framework for implementing distributed applications and smart environments for several reasons, including improvements to the latency and bandwidth of client-server applications and reducing vulnerability to network disconnection. In fact, mobile agents have several advantages in the development of various services in smart environments in addition to distributed applications.

  1. Mobile Usability

    DEFF Research Database (Denmark)

    Aryana, Bijan; Clemmensen, Torkil

    2013-01-01

    In this article, a country specific comparative mobile usability study is presented, using Iran and Turkey as the two chosen emerging/emergent nation exemplars of smartphone usage and adoption. In a focus group study, three mobile applications were selected by first-time users of smartphones....... In both countries, the music player application was tested, wherein common patterns of accessing and sorting songs emerged. Whereas the Iranian users appeared to be more interested in social networking via use of an SMS service, the Turkish users tended to prefer to apply hierarchies to their own daily...

  2. A Service Oriented Framework for Mobile Business Virtual Communities

    NARCIS (Netherlands)

    Subercaze, J.; Maret, P.; Calmet, J.; Pawar, P.

    2008-01-01

    The rise of the availability of a variety of mobile devices in the personal and professional domains leads to an increased need of middleware and organizational structures. Due to the recent improvement of the computing power of mobile devices, mobile users may now also act as service providers. We

  3. Meteorological satellite systems

    CERN Document Server

    Tan, Su-Yin

    2014-01-01

    “Meteorological Satellite Systems” is a primer on weather satellites and their Earth applications. This book reviews historic developments and recent technological advancements in GEO and polar orbiting meteorological satellites. It explores the evolution of these remote sensing technologies and their capabilities to monitor short- and long-term changes in weather patterns in response to climate change. Satellites developed by various countries, such as U.S. meteorological satellites, EUMETSAT, and Russian, Chinese, Japanese and Indian satellite platforms are reviewed. This book also discusses international efforts to coordinate meteorological remote sensing data collection and sharing. This title provides a ready and quick reference for information about meteorological satellites. It serves as a useful tool for a broad audience that includes students, academics, private consultants, engineers, scientists, and teachers.

  4. Theory of geostationary satellites

    CERN Document Server

    Zee, Chong-Hung

    1989-01-01

    Geostationary or equatorial synchronous satellites are a daily reminder of our space efforts during the past two decades. The nightly television satellite weather picture, the intercontinental telecommunications of television transmissions and telephone conversations, and the establishrnent of educational programs in remote regions on Earth are constant reminders of the presence of these satellites. As used here, the term 'geo­ stationary' must be taken loosely because, in the long run, the satellites will not remain 'stationary' with respect to an Earth-fixed reference frame. This results from the fact that these satellites, as is true for all satellites, are incessantly subject to perturbations other than the central-body attraction of the Earth. Among the more predominant pertur­ bations are: the ellipticity of the Earth's equator, the Sun and Moon, and solar radiation pressure. Higher harmonics of the Earth's potential and tidal effects also influence satellite motion, but they are of second­ order whe...

  5. A highly innovative global broadband mobile communication system concept

    Science.gov (United States)

    Wittig, Manfred

    2010-04-01

    Global mobile communication systems deployed in the 1990s (Iridium and Globalstar) failed to achieve the expected market success. However, recently a second generation of these two LEO constellations have been or will be procured. This shows evidence that global mobile satellite communications are attractive for a certain class of users. Basic requirements for mobile satellite communication networks are global coverage at high elevation angles, continuous availability and most important attractive service offers. For the first two reasons LEO constellations were designed and deployed. The large number of required satellites (remember the original Teledesic concept was designed containing 860 satellites) increases the CAPEX and consequently the service cost. This is probably the major reason for the limited commercial success of Iridium and Globalstar. An ideal global mobile (broadband) communication system shall provide global coverage at high elevation angles (not below e.g. 30°) with the lowest number of satellites. This seems to be contradictory. However, a solution will be presented that achieves global coverage which requires only five satellites and achieves high elevation angles even at polar locations. This orbit constellation is to be complemented with innovative payloads to achieve cost efficient broadband mobile services all over the Globe. Innovative L/S-band payload concepts will be introduced as well as Ka-band payloads.

  6. Securing Mobile Networks in an Operational Setting

    Science.gov (United States)

    Ivancic, William D.; Stewart, David H.; Bell, Terry L.; Paulsen, Phillip E.; Shell, Dan

    2004-01-01

    This paper describes a network demonstration and three month field trial of mobile networking using mobile-IPv4. The network was implemented as part of the US Coast Guard operational network which is a ".mil" network and requires stringent levels of security. The initial demonstrations took place in November 2002 and a three month field trial took place from July through September of 2003. The mobile network utilized encryptors capable of NSA-approved Type 1 algorithms, mobile router from Cisco Systems and 802.11 and satellite wireless links. This paper also describes a conceptual architecture for wide-scale deployment of secure mobile networking in operational environments where both private and public infrastructure is used. Additional issues presented include link costs, placement of encryptors and running routing protocols over layer-3 encryption devices.

  7. 77 FR 61027 - Notice of Lodging of Proposed Consent Decree Under the Clean Water Act and Safe Drinking Water Act

    Science.gov (United States)

    2012-10-05

    ... Clean Water Act and Safe Drinking Water Act at mobile home parks operated by defendants in Pennsylvania, Delaware and Virginia. The defendants treat sewage and provide drinking water at a number of its mobile... about drinking water problems. The Consent Decree requires payment of a civil penalty of...

  8. Sustainable Mobility

    DEFF Research Database (Denmark)

    Kjærulff, Aslak Aamot

    This paper combines strands of mobilities theory and planning theory, and develops a qualitative approach to look across emerging planning practices. By actively following 8 Danish urban and transport planners, over the course of 2 years, we learn how their practices have changed, inspired...

  9. Mobile Phone

    Institute of Scientific and Technical Information of China (English)

    籍万杰

    2004-01-01

    Your mobile phone rings.and instead of usual electronic signals,it's playing your favorite music.A friend sends your favorite song to cheer you up.One day,a record company might forward new records and music videos to your phone.

  10. Mobil nationalisme

    DEFF Research Database (Denmark)

    Koefoed, Lasse Martin

    2006-01-01

    , varer, mennesker og kapital men derimod en integreret del af disse tendenser. Gennem begrebet mobil nationalisme argumenteres der for en analytisk optik, hvor nationalisme forstås som en proces hvorigennem skiftende relationer og bevægelser mellem forskellige socio-rumlige skalaer som kroppen...

  11. Mobile IP

    NARCIS (Netherlands)

    Heijenk, Geert; Sallent, S.; Pras, A.

    1999-01-01

    The Internet is growing exponentially, both in the amount of traffic carried, and in the amount of hosts connected. IP technology is becoming more and more important, in company networks (Intranets), and also in the core networks for the next generation mobile networks. Further, wireless access to I

  12. Sustainable Mobility

    DEFF Research Database (Denmark)

    Kjærulff, Aslak Aamot

    This paper combines strands of mobilities theory and planning theory, and develops a qualitative approach to look across emerging planning practices. By actively following 8 Danish urban and transport planners, over the course of 2 years, we learn how their practices have changed, inspired...

  13. Mobile IP

    NARCIS (Netherlands)

    Heijenk, Gerhard J.; Sallent, S.; Pras, Aiko

    1999-01-01

    The Internet is growing exponentially, both in the amount of traffic carried, and in the amount of hosts connected. IP technology is becoming more and more important, in company networks (Intranets), and also in the core networks for the next generation mobile networks. Further, wireless access to

  14. Mobile Misfortune

    DEFF Research Database (Denmark)

    Vigh, Henrik Erdman

    2015-01-01

    for themselves and their families, it shows how involvement in the cocaine trade is both a curse and a catalyst. Though trading the drug may facilitate migration and mobility, generating social being and worth in the process, it is an activity that is haunted by the threat of deportation and the termination...

  15. Balancing Acts

    Science.gov (United States)

    ... Past Issues Special Section: Focus on Communication Balancing Acts Past Issues / Fall 2008 Table of Contents For ... scientific research on hearing, balance, smell, taste, voice, speech, and language—common elements in how we perceive ...

  16. Design and Implementation of Anti Lost Bluetooth Low Energy Mobile Device for Mobile Phone

    OpenAIRE

    Prajakta S. Chavan; Uttam L. Bombale

    2014-01-01

    Today mobile phone like smart phone, tablet are very costly ranging from 300 USD to 600 USD , to avoid them to get forget at any social places, we can have mobile device(gadget) which will warn us (beep)this device is left back .To make commercialize product which will act as mobile phone watchmen, with specification and characteristic like smallest device foot print, comfortable to carry along, ultra low power consumption to increase battery life and to avoid frequent chargin...

  17. Mobile-to-mobile wireless channels

    CERN Document Server

    Zajic, Alenka

    2013-01-01

    Present-day mobile communications systems can be classified as fixed-to-mobile because they allow mobility on only one end (e.g. the mobile phone to a fixed mobile operator's cell tower). In answer to the consumer demand for better coverage and quality of service, emerging mobile-to-mobile (M-to-M) communications systems allow mobile users or vehicles to directly communicate with each other. This practical book provides a detailed introduction to state-of-the-art M-to-M wireless propagation. Moreover, the book offers professionals guidance for rapid implementation of these communications syste

  18. Barcode Payment System in Trusted Mobile Devices

    Directory of Open Access Journals (Sweden)

    Vibha Kaw Raina

    2012-11-01

    Full Text Available Mobile payment is an application of mobile commerce which facilitates mobile commerce transactions by providing the mobile customer with a convenient means to pay. Many mobile payment methods have been proposed and implemented like user friendly, customer centric, merchant centric where security concerns are highly addressed. This paper proposes a mobile payment model with barcodes for mobile users to improve mobile user experience in mobile payment. Unlike other existing mobile payment systems, the proposed payment solution provides distinct advantages to support buy-and-sale products and services based on 2D Barcodes. The aim of this work is to integrate a model of payment with the financial services, including payment and banking ones, based on two primary capabilities: the use of computational resources of a trusted mobile device and the establishment of a user controlled channel with the customer’s bank. The proposed architecture is characterized bank-centric, since the bank acts consultatively, informatively and protectively for the end user and it offers flexibility, adaptability and continuous extendibility to open technologies.

  19. Potential markets for advanced satellite communications

    Science.gov (United States)

    Adamson, Steven; Roberts, David; Schubert, Leroy; Smith, Brian; Sogegian, Robert; Walters, Daniel

    1993-09-01

    This report identifies trends in the volume and type of traffic offered to the U.S. domestic communications infrastructure and extrapolates these trends through the year 2011. To describe how telecommunications service providers are adapting to the identified trends, this report assesses the status, plans, and capacity of the domestic communications infrastructure. Cable, satellite, and radio components of the infrastructure are examined separately. The report also assesses the following major applications making use of the infrastructure: (1) Broadband services, including Broadband Integrated Services Digital Network (BISDN), Switched Multimegabit Data Service (SMDS), and frame relay; (2) mobile services, including voice, location, and paging; (3) Very Small Aperture Terminals (VSAT), including mesh VSAT; and (4) Direct Broadcast Satellite (DBS) for audio and video. The report associates satellite implementation of specific applications with market segments appropriate to their features and capabilities. The volume and dollar value of these market segments are estimated. For the satellite applications able to address the needs of significant market segments, the report also examines the potential of each satellite-based application to capture business from alternative technologies.

  20. Potential markets for advanced satellite communications

    Science.gov (United States)

    Adamson, Steven; Roberts, David; Schubert, Leroy; Smith, Brian; Sogegian, Robert; Walters, Daniel

    1993-01-01

    This report identifies trends in the volume and type of traffic offered to the U.S. domestic communications infrastructure and extrapolates these trends through the year 2011. To describe how telecommunications service providers are adapting to the identified trends, this report assesses the status, plans, and capacity of the domestic communications infrastructure. Cable, satellite, and radio components of the infrastructure are examined separately. The report also assesses the following major applications making use of the infrastructure: (1) Broadband services, including Broadband Integrated Services Digital Network (BISDN), Switched Multimegabit Data Service (SMDS), and frame relay; (2) mobile services, including voice, location, and paging; (3) Very Small Aperture Terminals (VSAT), including mesh VSAT; and (4) Direct Broadcast Satellite (DBS) for audio and video. The report associates satellite implementation of specific applications with market segments appropriate to their features and capabilities. The volume and dollar value of these market segments are estimated. For the satellite applications able to address the needs of significant market segments, the report also examines the potential of each satellite-based application to capture business from alternative technologies.

  1. Urban Mobility

    DEFF Research Database (Denmark)

    2017-01-01

    This anthology is the proceedings publication from the 2015 NAF Symposium in Malmö, Sweden. The aim of the 2015 NAF Symposium “Urban Mobility – Architectures, Geographies and Social Space” was to facilitate a cross-disciplinary discussion on urban mobility in which the juxtaposition of different...... discursive perceptions of the concept would foster greater insight into and understanding of both the challenges and potentials that it represents. It focused on some of the key themes currently facing cities and the urban: the transformation of the city and our built environment; migration; rural decline......; the interaction between city, architecture, and inhabitants; the role of architects and architecture in the creation of democratic and sustainable urban contexts; the city and its representation; the politics of intervention; and the actions of governing and developing. This proceedings publication from...

  2. Robotique Mobile

    OpenAIRE

    Filliat, David

    2011-01-01

    1 Introduction I Les bases de la navigation 2 Les différents types de navigation 3 Les sources d'information 4 Matériels courants en robotique mobile II Navigation réactive 5 Navigation vers un but 6 Évitement d'obstacles 7 Apprentissage par renforcement III Navigation utilisant une carte 8 Localisation, Cartographie et Planification 9 Les représentations de l'environne 10 Localisation 11 Cartographie 12 Planification; Engineering school

  3. The African Mobile Story

    DEFF Research Database (Denmark)

    This book identifies the factors that has enabled the growth of mobile telephony in Africa. The book covers the regulatory factors, the development and usage of mobile application, mobile security and sustainable power source for mobile networks......This book identifies the factors that has enabled the growth of mobile telephony in Africa. The book covers the regulatory factors, the development and usage of mobile application, mobile security and sustainable power source for mobile networks...

  4. The African Mobile Story

    DEFF Research Database (Denmark)

    This book identifies the factors that has enabled the growth of mobile telephony in Africa. The book covers the regulatory factors, the development and usage of mobile application, mobile security and sustainable power source for mobile networks......This book identifies the factors that has enabled the growth of mobile telephony in Africa. The book covers the regulatory factors, the development and usage of mobile application, mobile security and sustainable power source for mobile networks...

  5. Seamless Handovers in Cobra Teardrop Satellite Arrays

    Science.gov (United States)

    Draim, John E.; Cefola, Paul J.; Ernandes, Kenneth J.

    2007-06-01

    Satellite systems provide the most efficient and possibly the only means of achieving two-way global communications with mobile systems (ships, aircraft, and vehicular traffic). To date, such systems have used only circular orbits, either GEO or LEO. Medium altitude elliptical constellations, on the other hand, can provide an efficient and affordable alternative to these architectures. Users also benefit from their very high average and minimum elevation angles, resulting in minimum signal attenuation. Cobra Teardrop is unique in that it employs time synchronized 8-h left- and right-leaning elliptical orbits giving mid-latitude observers the illusion of viewing a single satellite continuously orbiting almost directly overhead! In reality, observers see six different satellites per day, for 4 h each (while in their active duty cycles). By design, Teardrop satellites are physically in very close proximity at the handover points. This favorable geometry can be utilized to achieve a seamless handover from one satellite to the other (not requiring any electronic buffering). Handover is accomplished at the precise instant that the total path lengths from the transmitting station through both satellites to the receiving station are exactly equal. In these improved Cobra Teardrop arrays, an order of magnitude increase in global communications capacity (equivalent GEO slots) can be realized over earlier Basic Cobra systems. For decades into the future, these new orbital systems could satisfy a widely expanding range of commercial, government, and military high data rate communication requirements. These would include, but not be limited to, satellite cellular, air traffic control, meteorological, and combat net radio systems. With these arrays, a much larger number of system operators could be supported, without mutual electronic interference, than would ever be possible with circular orbits.

  6. Network Mobiles

    Directory of Open Access Journals (Sweden)

    Alhamali Masoud Alfrgani .Ali

    2015-07-01

    Full Text Available Mobile devices are becoming increasingly popular for delivering multimedia content, particularly by means of streaming. The main disadvantage of these devices is their limited battery life. Unfortunately, streaming of multimedia content causes the battery of the device to discharge very fast, often causing the battery to deplete before the streaming task finishes, resulting in user dissatisfaction. It is generally not possible to charge the device while on the go as electricity socket and charger are required. Therefore, to avoid this user dissatisfaction, it is necessary to find ways to prolong the battery lifetime and to support the completion of the multimedia streaming tasks. A typical architecture for mobile multimedia streaming is presented In this architecture, a wired server streams multimedia content over a wireless IP network to a number of client devices. These devices could be PDAs, smartphones or any other mobile device with 802.11 connectivity. In relation to possible power savings, the multimedia streaming process can be described as consisting of three stages: reception, decoding and playing. Other researchers have shown that energy savings can be made in each stage, for example by using pre-buffering in the reception stage, feedback control during decoding and backlight adjustment for playing. However, it is not a common practice to combine energy savings in the three stages in order to achieve the best

  7. A satellite system for multimedia personal communications at Ka-band and beyond

    Science.gov (United States)

    Vatalaro, F.; Losquadro, G.

    1995-01-01

    The main characteristics of the satellite extremely high frequency (EHF) communication of multimedia mobile services (SECOMS) system are given and the results of the preliminary analysis are included. The SECOMS provides a first generation Ka band system with coverage over Western Europe, in order to satisfy business user needs of very large bandwidths and terminal mobility. The satellite system also provides a second generation EHF enhanced system with increased capacity and enlarged coverage, to serve all of Europe and the nearby countries.

  8. Satellite communication antenna technology

    Science.gov (United States)

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

    1983-01-01

    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.

  9. Methods of satellite oceanography

    Science.gov (United States)

    Stewart, R. H.

    1985-01-01

    The theoretical basis for remote sensing measurements of climate and ocean dynamics is examined. Consideration is given to: the absorption of electromagnetic radiation in the atmosphere; scattering in the atmosphere; and satellite observations using visible light. Consideration is also given to: the theory of radio scatter from the sea; scatter of centimeter waves from the sea; and the theory of operation of synthetic aperture radars. Additional topics include: the coordinate systems of satellite orbits for oceanographic remote sensing applications; the operating features of the major U.S. satellite systems for viewing the ocean; and satellite altimetry.

  10. ACSSB land mobile earth station

    Science.gov (United States)

    Taira, Shinichi; Ikegami, Tetsushi; Suzuki, Ryutaro; Suzuki, Shoichi; Kawahara, Hideki; Tada, Shun-Ichi

    1990-03-01

    This paper describes the performance of the land mobile earth station using the Amplitude Companded Single Sideband (ACSSB) modulation technique developed for mobile satellite communications and results of the field experiments which were conducted in rural, suburban, and urban areas. This ACSSB system uses a 3-kHz pilot tone, and the voice frequency band is from 300 to 2500 Hz. The experiments show that the required C/N0 for voice communications is 40 dBHz and the required C/N0 for pilot signal tracking is 34 dBHz. Voice quality in rural and suburban areas was degraded slightly. In urban areas shadowings due to the presence of large buildings and trees caused signal losses. A comparison of the ACSSB system with the conventional narrow-band frequency-modulation system indicates that the ACSSB system can transmit voice signals more efficiently.

  11. Astronauts Gardner and Allen bringing Westar VI satellite into payload bay

    Science.gov (United States)

    1984-01-01

    Astronaut Dale A. Gardner, left, and Joseph P. Allen IV work together with Dr. Anna L. Fisher (in the Discovery controlling the remote manipulator system (RMS) arm) to bring the Westar VI satellite into the Discovery's payload bay. Allen is on a mobile foot restraint, which is attached to the RMS end effector. Gardner uses the manned maneuvering unit (MMU) on the other side of the satellite. He is attempting to remove the stinger device from the now stabilized satellite.

  12. NETWORK MOBILITY SUPPORTED PROXY MOBILE IPV6

    Directory of Open Access Journals (Sweden)

    Ananthi Jebaseeli SamuelRaj

    2014-01-01

    Full Text Available Proxy Mobile IPV6 (PMIPV6 is a network-based mobility management protocol, designed to keep track of individual mobile node’s movement. So a mobile node can easily roam in PMIPV6 network without changing it’s IP address. Network Mobility-Basic Support Protocol (NEMO-BSP, based on MIPV6, is the protocol designed for mobility management of NEMO in MPIV6 network. But NEMO-BSP cannot be directly used in PMIPV6 due to differences in the underlying protocols. To make PMIPV6 as a complete mobility management protocol, functionality of PMIPV6 should be enhanced to support network mobility in PMIPV6. This work enhances functionality of PMIPV6 and NEMO-BSP protocols and proposes a new architecture called NEMO supported PMIPV6 that supports movement of mobile nodes as well as network mobility in PMIPV6 network.

  13. Satellites of spiral galaxies

    Science.gov (United States)

    Zaritsky, Dennis; Smith, Rodney; Frenk, Carlos; White, Simon D. M.

    1993-01-01

    We present a survey of satellites around a homogeneous set of late-type spirals with luminosity similar to that of the Milky Way. On average, we find fewer than 1.5 satellites per primary, but we argue that we can treat the survey as an ensemble and so derive the properties of the halo of a 'typical' isolated spiral. The projected density profile of the ensemble falls off approximately as 1/r. Within 50 kpc the azimuthal distribution of satellites shows some evidence for the 'Holmberg effect', an excess near the minor axis of the primary; however, at larger projected distances, the distribution appears isotropic. There is a weak but significant correlation between the size of a satellite and its distance from its primary, as expected if satellites are tidally truncated. Neither Hubble type nor spectral characteristics correlate with apparent separation. The ensemble of satellites appears to be rotating at about 30 km/s in the same direction as the galactic disk. Satellites on prograde orbits tend to be brighter than those on retrograde orbits. The typical velocity difference between a satellite and its primary shows no clear dependence either on apparent separation, or on the rotation speed of the primary. Thus our survey demonstrates that isolated spiral galaxies have massive halos that extend to many optical radii.

  14. Predictability of Mobile Phone Associations

    DEFF Research Database (Denmark)

    Jensen, Bjørn Sand; Larsen, Jan; Hansen, Lars Kai

    2010-01-01

    Prediction and understanding of human behavior is of high importance in many modern applications and research areas ranging from context-aware services, wireless resource allocation to social sciences. In this study we collect a novel dataset using standard mobile phones and analyze how...... representation, and general behavior. This is of vital interest in the development of context-aware services which rely on forecasting based on mobile phone sensors....... the predictability of mobile sensors, acting as proxies for humans, change with time scale and sensor type such as GSM and WLAN. Applying recent information theoretic methods, it is demonstrated that an upper bound on predictability is relatively high for all sensors given the complete history (typically above 90...

  15. Secret Key Generation From Mobility

    CERN Document Server

    Gungor, Onur; Koksal, C Emre

    2011-01-01

    We consider secret key generation from relative localization information of a pair of nodes in a mobile wireless network in the presence of a mobile eavesdropper. Our scheme consists of two phases: in the first phase, legitimate node pair exchanges beacon signals to establish localization information based on noisy observations of these beacons; in the second phase, nodes generate secret key bits via a public discussion. Our problem can be categorized under the source models of information theoretic secrecy, where the distance between the legitimate nodes acts as the observed common randomness. We characterize the achievable secret key bit rate in terms of the observation noise variance at the legitimate nodes and the eavesdropper. This work provides a framework that combines information theoretic secrecy and wireless localization, and proves that the localization information provides a significant additional resource for secret key generation in mobile wireless networks.

  16. Social Mobilization.

    Science.gov (United States)

    Rogers, Todd; Goldstein, Noah J; Fox, Craig R

    2017-09-25

    This article reviews research from several behavioral disciplines to derive strategies for prompting people to perform behaviors that are individually costly and provide negligible individual or social benefits but are meaningful when performed by a large number of individuals. Whereas the term social influence encompasses all the ways in which people influence other people, social mobilization refers specifically to principles that can be used to influence a large number of individuals to participate in an activity. The motivational force of social mobilization is amplified by the fact that others benefit from the encouraged behaviors, and its overall impact is enhanced by the fact that people are embedded within social networks. This article may be useful to those interested in the provision of public goods, collective action, and prosocial behavior, and we give special attention to field experiments on election participation, environmentally sustainable behaviors, and charitable giving. Expected final online publication date for the Annual Review of Psychology Volume 69 is January 4, 2018. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.

  17. Mobile Transporter

    Science.gov (United States)

    2001-01-01

    The Space Shuttle Atlantis, STS-110 mission, deployed this railcar, called the Mobile Transporter, and an initial 43-foot section of track, the S0 (S-zero) truss, preparing the International Space Station (ISS) for future spacewalks. The first railroad in space, the Mobile Transporter will allow the Station's robotic arm to travel up and down the finished truss for future assembly and maintenance. The 27,000-pound S0 truss is the first of 9 segments that will make up the Station's external framework that will eventually stretch 356 feet (109 meters), or approximately the length of a football field. The completed truss structure will hold solar arrays and radiators to provide power and cooling for additional international research laboratories from Japan and Europe that will be attached to the Station. The Space Shuttle Orbiter Atlantis, STS-110 mission, was launched April 8, 2002 and returned to Earth April 19, 2002. STS-110's Extravehicular Activity (EVA) marked the first use of the Station's robotic arm to maneuver spacewalkers around the Station.

  18. Mobile Misfortune

    Directory of Open Access Journals (Sweden)

    Henrik Vigh

    2015-06-01

    Full Text Available This article examines how the emergent cocaine trade in Bissau, the capital of the west African country of Guinea-Bissau, has become entangled with and trickled into the life worlds, hopes and fears of the city's many impoverished young men. The article is divided into two parts. While the first part looks at the predicament of youth and the hope of migration in Bissau, the second illuminates the anguish of deportation and the despair of being forcefully "displaced back home." Following in the footsteps of the young men that seek to navigate the cocaine trade, in order to obtain better lives for themselves and their families, it shows how involvement in the cocaine trade is both a curse and a catalyst. Though trading the drug may facilitate migration and mobility, generating social being and worth in the process, it is an activity that is haunted by the threat of deportation and the termination of the mobility it enables. This article, thus, looks at the motives and manners in which young men in Bissau become caught up in transnational flows of cocaine. It shows how motion is emotively anchored and affectively bound: tied to and directed toward a feeling of worth and realisation of being, and how migration from the global South often has negative potentiality as an end-point via the ascription of illegality and condition of deportability that shade it.

  19. Mobility Impact on Performance of Mobile Grids

    CERN Document Server

    Nandeppanavar, A S; Manvi, S S; Shridhar,

    2010-01-01

    Wireless mobile grids are one of the emerging grid types, which help to pool the resources of several willing and cooperative mobile devices to resolve a computationally intensive task. The mobile grids exhibit stronger challenges like mobility management of devices, providing transparent access to grid resources, task management and handling of limited resources so that resources are shared efficiently. Task execution on these devices should not be affected by their mobility. The proposed work presents performance evaluation of wireless mobile grid using normal walk mobility model. The normal walk model represents daily motion of users and the direction of motion is mostly symmetric in a real life environment, thus it is effective in location updating of a mobile station and in turn helps task distribution among these available mobile stations. Some of the performance parameters such as Task Execution Time, task failure rate, communication overhead on Brokering Server and Monitoring Cost are discussed.

  20. Beginnings of Satellite Navigation

    Directory of Open Access Journals (Sweden)

    Miljenko Solarić

    2008-05-01

    Full Text Available The first satellite navigation system called the Navy Navigation Satellite System (NNSS or TRANSIT was planned in the USA in 1958. It consisted of 5-6 artificial Earth satellites, was set in motion for the USA military in 1964, and in 1967 for civilian purposes. The frequency shift of received radio waves emitted from the satellite and caused by the Doppler effect was measured. The TRANSIT satellite speed of approaching or moving away was derived from that; the TRANSIT satellites emmited also their own coordinates. Then the ship's position was determined by an intersection of three hyperboloids, which were determined from differences of distances in three time intervals. Maintenance of this navigation system was stopped in 1996, but it is still being used in the USA Navy for exploring the ionosphere. Furthermore, results of Doppler measurements in international projects at the Hvar Observatory from 1982 and 1983. This was the first time in Croatia and the former country that the coordinates of the Hvar Observatory were determined in the unique world coordinate system WGS'72. The paper ends with a brief representation of the Tsiklon Doppler navigation system produced in the former Soviet Union, and there is a list of some of numerous produced and designed satellite navigation systems.Ključne riječi

  1. 基于成本控制角度卫星移动通信终端的零中频接收机设计%Design of Zero-IF Receiver of Satellite Mobile Communication Terminal Based on Cost Control Point

    Institute of Scientific and Technical Information of China (English)

    许敏; 陈伟

    2014-01-01

    以往卫星移动终端的接收机其功耗大,价格高,使得公司设备预算居高不下,尤其对于中小型的通信公司而言,更是急于降低这项成本。零中频(Zero-IF)接收机又称为直接变频(Direct Conversion)接收机,其结构简单,具有很高集成度,对镜像信号抑制的要求也不高,且功耗较小也使得成本较低。因此采用零中频结构来实现无线接收机是未来的一个趋势,正成为射频接收机中极具竞争力的一种构案。%Receiver of satellite mobile terminals in past is of great power consumption,high price,which make company's’equipment budget high,especially for small and medium-sized communications company.Zero intermediate frequency(Zero-IF) receiver is also known as(Direct Conversion receiver which has simple structure and high integration.Meanwhile,the requirement of image signal suppression is not high.Less power consumption make it cost less.So it is a trend to use Zero-IF structure to realize the wireless receiver in the future.Zero-IF structure is becoming a highly competitive in RF receiver.

  2. Direct broadcast satellite-radio, receiver development

    Science.gov (United States)

    Vaisnys, A.; Bell, D.; Gevargiz, J.; Golshan, Nasser

    1993-01-01

    The status of the ongoing Direct Broadcast Satellite-Radio (DBS-R) Receiver Development Task being performed at the Jet Propulsion Laboratory, California Institute of Technology (JPL) is reported. This work is sponsored by the Voice of America/U.S. Information Agency through an agreement with NASA. The objective of this task is to develop, build, test, and demonstrate a prototype receiver that is compatible with reception of digital audio programs broadcast via satellites. The receiver is being designed to operate under a range of reception conditions, including fixed, portable, and mobile, as well as over a sufficiently wide range of bit rates to accommodate broadcasting systems with different cost/audio quality objectives. While the requirements on the receiver are complex, the eventual goal of the design effort is to make the design compatible with low cost production as a consumer product. One solution may be a basic low cost core design suitable for a majority of reception conditions, with optional enhancements for reception in especially difficult environments. Some of the receiver design parameters were established through analysis, laboratory tests, and a prototype satellite experiment accomplished in late 1991. Many of the necessary design trades will be made during the current simulation effort, while a few of the key design options will be incorporated into the prototype for evaluation during the planned satellite field trials.

  3. Direct broadcast satellite-radio, receiver development

    Science.gov (United States)

    Vaisnys, A.; Bell, D.; Gevargiz, J.; Golshan, Nasser

    The status of the ongoing Direct Broadcast Satellite-Radio (DBS-R) Receiver Development Task being performed at the Jet Propulsion Laboratory, California Institute of Technology (JPL) is reported. This work is sponsored by the Voice of America/U.S. Information Agency through an agreement with NASA. The objective of this task is to develop, build, test, and demonstrate a prototype receiver that is compatible with reception of digital audio programs broadcast via satellites. The receiver is being designed to operate under a range of reception conditions, including fixed, portable, and mobile, as well as over a sufficiently wide range of bit rates to accommodate broadcasting systems with different cost/audio quality objectives. While the requirements on the receiver are complex, the eventual goal of the design effort is to make the design compatible with low cost production as a consumer product. One solution may be a basic low cost core design suitable for a majority of reception conditions, with optional enhancements for reception in especially difficult environments. Some of the receiver design parameters were established through analysis, laboratory tests, and a prototype satellite experiment accomplished in late 1991. Many of the necessary design trades will be made during the current simulation effort, while a few of the key design options will be incorporated into the prototype for evaluation during the planned satellite field trials.

  4. Mobile video with mobile IPv6

    CERN Document Server

    Minoli, Daniel

    2012-01-01

    Increased reliance on mobile devices and streaming of video content are two of the most recent changes that have led those in the video distribution industry to be concerned about the shifting or erosion of traditional advertising revenues. Infrastructure providers also need to position themselves to take advantage of these trends. Mobile Video with Mobile IPv6provides an overview of the current mobile landscape, then delves specifically into the capabilities and operational details of IPv6. The book also addresses 3G and 4G services, the application of Mobile IPv6 to streaming and other mobil

  5. Digital audio and video broadcasting by satellite

    Science.gov (United States)

    Yoshino, Takehiko

    In parallel with the progress of the practical use of satellite broadcasting and Hi-Vision or high-definition television technologies, research activities are also in progress to replace the conventional analog broadcasting services with a digital version. What we call 'digitalization' is not a mere technical matter but an important subject which will help promote multichannel or multimedia applications and, accordingly, can change the old concept of mass media, such as television or radio. NHK Science and Technical Research Laboratories has promoted studies of digital bandwidth compression, transmission, and application techniques. The following topics are covered: the trend of digital broadcasting; features of Integrated Services Digital Broadcasting (ISDB); compression encoding and transmission; transmission bit rate in 12 GHz band; number of digital TV transmission channels; multichannel pulse code modulation (PCM) audio broadcasting system via communication satellite; digital Hi-Vision broadcasting; and development of digital audio broadcasting (DAB) for mobile reception in Japan.

  6. Using GPS for studying pastoral mobility

    DEFF Research Database (Denmark)

    Adriansen, Hanne Kirstine

    2017-01-01

    In 1997 I embarked on a PhD to study mobility amongst nomadic pastoralists in Senegal. Previous studies had largely been conducted by anthropologists who through ethnographic fieldwork followed the nomadic pastoralists for long periods of time and did their own sketches of the movements. As a human...... geographer familiar with satellite remote sensing and GIS, I pondered how these relatively new technologies could be combined with classic ethnographic fieldwork, which we also use in human geography. I decided to use handheld GPS devices for tracking the pastoralists and their herds. My study was, as far...... as I know, the first one to use GPS for studying pastoral mobility. A total of 10 pastoralists were trained in using a GPS and asked to map their movements. This information was combined with satellite imagery on one hand and qualitative interviews on the other. This case study provides an account...

  7. Using GPS for studying pastoral mobility

    DEFF Research Database (Denmark)

    Adriansen, Hanne Kirstine

    2017-01-01

    geographer familiar with satellite remote sensing and GIS, I pondered how these relatively new technologies could be combined with classic ethnographic fieldwork, which we also use in human geography. I decided to use handheld GPS devices for tracking the pastoralists and their herds. My study was, as far...... as I know, the first one to use GPS for studying pastoral mobility. A total of 10 pastoralists were trained in using a GPS and asked to map their movements. This information was combined with satellite imagery on one hand and qualitative interviews on the other. This case study provides an account...... of the practical aspects of using GPS, taking the reader to the heart of some methodological issues that arose in the course of the research. The case sheds light on the particular challenges in using GPS for eliciting information about pastoral mobility. Thinking about such challenges leads to more general...

  8. Trends In Satellite Communication

    Science.gov (United States)

    Poley, William A.; Stevens, Grady H.; Stevenson, Steven M.; Lekan, Jack; Arth, Clifford H.; Hollansworth, James E.; Miller, Edward F.

    1988-01-01

    Report assesses trends in satellite communication from present to year 2010. Examines restrictions imposed by limited spectrum resource and technology needs created by trends. Personal communications, orbiting switchboards, and videophones foreseen.

  9. Domestic Communication Satellites

    Science.gov (United States)

    Horowitz, Andrew

    1974-01-01

    A discussion of the Federal Communications Commission's new policy on domestic satellites in light of our 1) military and economic history; 2) corporate interests; 3) citizen surveillance; and 4) media control. (HB)

  10. Handbook of satellite applications

    CERN Document Server

    Madry, Scott; Camacho-Lara, Sergio

    2013-01-01

    Top space experts from around the world have collaborated to produce this comprehensive, authoritative, and clearly illustrated reference guide to the fast growing, multi-billion dollar field of satellite applications and space communications. This handbook, done under the auspices of the International Space University based in France, addresses not only system technologies but also examines market dynamics, technical standards and regulatory constraints. The handbook is a completely multi-disciplinary reference book that covers, in an in-depth fashion, the fields of satellite telecommunications, Earth observation, remote sensing, satellite navigation, geographical information systems, and geosynchronous meteorological systems. It covers current practices and designs as well as advanced concepts and future systems. It provides a comparative analysis of the common technologies and design elements for satellite application bus structures, thermal controls, power systems, stabilization techniques, telemetry, com...

  11. Biological satellite Kosmos-936

    Science.gov (United States)

    Vedeshin, L. A.

    1978-01-01

    A description is given of physiological experiments performed on the biological satellite Kosmos-936. Other experiments to determine the electrostatic and dielectric responses to the effects of cosmic radiation are discussed.

  12. Small Satellite Transporter Project

    Data.gov (United States)

    National Aeronautics and Space Administration — The primary objective is to determine whether this small satellite transporter is capable of transporting at least four 6U CubeSats is possible for a given set of...

  13. Using Satellite Images for Wireless Network Planing in Baku City

    Science.gov (United States)

    Gojamanov, M.; Ismayilov, J.

    2013-04-01

    It is a well known fact that the Information-Telecommunication and Space research technologies are the fields getting much more benefits from the achievements of the scientific and technical progress. In many cases, these areas supporting each other have improved the conditions for their further development. For instance, the intensive development in the field of the mobile communication has caused the rapid progress of the Space research technologies and vice versa.Today it is impossible to solve one of the most important tasks of the mobile communication as Radio Frecance planning without the 2D and 3D digital maps. The compiling of such maps is much more efficient by means of the space images. Because the quality of the space images has been improved and developed, especially at the both spectral and spatial resolution points. It has been possible to to use 8 Band images with the spatial resolution of 50 sm. At present, in relation to the function 3G of mobile communications one of the main issues facing mobile operator companies is a high-precision 3D digital maps. It should be noted that the number of mobile phone users in the Republic of Azerbaijan went forward other Community of Independent States Countries. Of course, using of aerial images for 3D mapping would be optimal. However, depending on a number of technical and administrative problems aerial photography cannot be used. Therefore, the experience of many countries shows that it will be more effective to use the space images with the higher resolution for these issues. Concerning the fact that the mobile communication within the city of Baku has included 3G function there were ordered stereo images wih the spatial resolution of 50 cm for the 150 sq.km territory occupying the central part of the city in order to compile 3D digital maps. The images collected from the WorldView-2 satellite are 4-Band Bundle(Pan+MS1) stereo images. Such kind of imagery enable to automatically classificate some required

  14. MOBILITY: A SYSTEMS APPROACH

    Directory of Open Access Journals (Sweden)

    Mykola I. Striuk

    2015-10-01

    Full Text Available A comprehensive study on the problem of mobility in the socio-educational and technical systems was carried out: the evolution of the concept of mobility in scientific sources of XIX–XXI centuries was analyzed and the new sources on the issue of mobility introduced into scientific circulation, the interrelation of the types of mobility in the socio-pedagogical and technical systems are theoretically grounded, an integrative model of mobility in the information society is proposed. The major trends in academic mobility are identified (the transition from student mobility to mobility programs and educational services providers, the new mobility programs (franchising, double/joint degrees, combinations, nostrification etc. are characterized. The new types of mobility providers are reviewed and attention is focused on virtual universities that are now the basis of virtual mobility of students and activities which are based on the use of new ICT in higher education, especially – the Internet and mobile learning environments.

  15. Mobile Inquiry Based Learning

    NARCIS (Netherlands)

    Specht, Marcus

    2012-01-01

    Specht, M. (2012, 8 November). Mobile Inquiry Based Learning. Presentation given at the Workshop "Mobile inquiry-based learning" at the Mobile Learning Day 2012 at the Fernuniversität Hagen, Hagen, Germany.

  16. Mobile Inquiry Based Learning

    NARCIS (Netherlands)

    Specht, Marcus

    2012-01-01

    Specht, M. (2012, 8 November). Mobile Inquiry Based Learning. Presentation given at the Workshop "Mobile inquiry-based learning" at the Mobile Learning Day 2012 at the Fernuniversität Hagen, Hagen, Germany.

  17. Satellite observation of particulate organic carbon dynamics in ...

    Science.gov (United States)

    Particulate organic carbon (POC) plays an important role in coastal carbon cycling and the formation of hypoxia. Yet, coastal POC dynamics are often poorly understood due to a lack of long-term POC observations and the complexity of coastal hydrodynamic and biogeochemical processes that influence POC sources and sinks. Using field observations and satellite ocean color products, we developed a nw multiple regression algorithm to estimate POC on the Louisiana Continental Shelf (LCS) from satellite observations. The algorithm had reliable performance with mean relative error (MRE) of ?40% and root mean square error (RMSE) of ?50% for MODIS and SeaWiFS images for POC ranging between ?80 and ?1200 mg m23, and showed similar performance for a large estuary (Mobile Bay). Substantial spatiotemporal variability in the satellite-derived POC was observed on the LCS, with high POC found on the inner shelf (satellite data with carefully developed algorithms can greatly increase

  18. Advances in satellite communications

    CERN Document Server

    Minoli, Daniel

    2015-01-01

    Discussing advances in modulation techniques and HTS spotbeam technologiesSurveying emerging high speed aeronautical mobility services and maritime and other terrestrial mobility servicesAssessing M2M (machine-to-machine) applications, emerging Ultra HD video technologies and new space technology

  19. DFH-3 Satellite Platform

    Institute of Scientific and Technical Information of China (English)

    RenShufang

    2005-01-01

    The DFH-3 satellite platform is designed and developed by China Academy of Space Technology (CAST). It is a medium capability communications satellite platform. The platform adopts threeaxis attitude stabilization control system, having solar array output power of 1.7kW by the end of its design lifetime of 8 years. Its mass is 2100kg with payload capacity of 220kg.

  20. ASTRID II satellit projekt

    DEFF Research Database (Denmark)

    Jørgensen, John Leif; Primdahl, Fritz

    1997-01-01

    The report describes the instruments developed for the Swedish micro satellite "ASTRID II". Specifications of the two instruments realized under this contract, a Stellar Compass and a CSC magnetometer are given follwed by a description of the project status and plan.......The report describes the instruments developed for the Swedish micro satellite "ASTRID II". Specifications of the two instruments realized under this contract, a Stellar Compass and a CSC magnetometer are given follwed by a description of the project status and plan....

  1. Cooperating mobile robots

    Energy Technology Data Exchange (ETDEWEB)

    Harrington, John J.; Eskridge, Steven E.; Hurtado, John E.; Byrne, Raymond H.

    2004-02-03

    A miniature mobile robot provides a relatively inexpensive mobile robot. A mobile robot for searching an area provides a way for multiple mobile robots in cooperating teams. A robotic system with a team of mobile robots communicating information among each other provides a way to locate a source in cooperation. A mobile robot with a sensor, a communication system, and a processor, provides a way to execute a strategy for searching an area.

  2. Trends in Mobile Marketing

    OpenAIRE

    Chocholová, Petra

    2010-01-01

    The principal aim of this thesis is to assess the state of the mobile marketing as of the first quarter of 2011 and to discuss various scenarios of the future development. This thesis defines the terms "mobile marketing" and "mobile advertising" and identifies the main players in the industry. It explores the main categories of mobile advertising such as mobile messaging, in-content and mobile internet advertising. Later, it analyzes the latest trends in the industry and describes in detail t...

  3. Narrowband coherent data transmission-mobile

    OpenAIRE

    Bateman, A.; McGeehan, JP

    1987-01-01

    The authors investigate the practical realization of pilot-based channel equalization systems, their integration into coherent data demodulation techniques, and their performance as compared with coherent data systems utilizing the data signal alone. Most of the analysis is associated with the land mobile environment, which is arguably the most hostile environment for data transmission. However many of the results and remarks made are equally applicable to the aeronautical, sea, and satellite...

  4. Satellite formation. II

    Science.gov (United States)

    Harris, A. W.

    1978-01-01

    A satellite formation model is extended to include evolution of planetary ring material and elliptic orbital motion. In this model the formation of the moon begins at a later time in the growth of the earth, and a significant fraction of the lunar material is processed through a circumterrestrial debris cloud where volatiles might have been lost. Thus, the chemical differences between the earth and moon are more plausibly accounted for. Satellites of the outer planets probably formed in large numbers throughout the growth of those planets. Because of rapid inward evolution of the orbits of small satellites, the present satellite systems represent only satellites formed in the last few percent of the growths of their primaries. The rings of Saturn and Uranus are most plausibly explained as the debris of satellites disrupted within the Roche limit. Because such a ring would collapse onto the planet in the course of any significant further accretion by the planet, the rings must have formed very near or even after the conclusion of accretion.

  5. Street navigation using visual information on mobile phones

    DEFF Research Database (Denmark)

    Nguyen, Phuong Giang; Andersen, Hans Jørgen; Høilund, Carsten

    2010-01-01

    Applications with street navigation have been recently introduced on mobile phone devices. A major part of existing systems use integrated GPS as input for indicating the location. However, these systems often fail or make abrupt shifts in urban environment due to occlusion of satellites. Further......Applications with street navigation have been recently introduced on mobile phone devices. A major part of existing systems use integrated GPS as input for indicating the location. However, these systems often fail or make abrupt shifts in urban environment due to occlusion of satellites...

  6. CHINA LAUNCHES NEW SCIENTIFIC SATELLITE

    Institute of Scientific and Technical Information of China (English)

    2004-01-01

    China on Sept. 27, 2004 launched a scientific satellite atop a Long March 2D carrier rocket from Jiuquan Satellite Launch Center in Gansu province. 10 minutes after the launch, the satellite entered a preset orbit and is running sound at the orbit. It is the 20th recoverable satellite for scientific and technological

  7. Mobile Schools for a Mobile World

    Science.gov (United States)

    Booth, Susan

    2013-01-01

    Overwhelmingly, independent schools are embracing mobile devices--laptops, iPads or other tablets, and smartphones--to enhance teaching and learning. This article describes the results of the "NAIS 2012 Mobile Learning Survey." Among its findings were that 75 percent of NAIS-member schools currently use mobile learning devices in at…

  8. Experimental Satellite 2 Successfully Launched

    Institute of Scientific and Technical Information of China (English)

    LiuJie

    2004-01-01

    Small satellite Experimental Satellite 2 (SY-2) was launched by LM-2C launch vehicle from Xichang Satellite Launch Center on Nov. 18, 2004. Later the satellite entered the preset sun-synchronous orbit, which is 700 kilometers above the earth. The launch was the eighthmission this year by China Aerospace Science and Technology Corporation(CASC), which aims to test the technology of the satellite, conduct survey and monitoring of the land and resources and geographical environment on a trial basis.

  9. China's Meteorological Satellite Application System

    Institute of Scientific and Technical Information of China (English)

    Zhang Jiashen

    2008-01-01

    @@ China's meteorological satellite program consists of five systems,namely the satellite system,the launch vehicle system,the launch center system,TT&C and the ground application system.The satellite system consists of FengYun (FY) polar orbiting series and FY geostationary series,which are launched by LM launch vehicles from Taiyan Satellite Launch Center (TSLC) and Xichang Satellite Launch Center (XSLC) respectively.

  10. Efficient mission control for the 48-satellite Globalstar Constellation

    Science.gov (United States)

    Smith, Dan

    1994-11-01

    The Globalstar system is being developed by Globalstar, Limited Partnership and will utilize 48 satellites in low earth orbit (See Figure 1) to create a world-wide mobile communications system consistent with Vice President Gore's vision of a Global Information Infrastructure. As a large long term commercial system developed by a newly formed organization, Globalstar provides an excellent opportunity to explore innovative solutions for highly efficient satellite command and control. Design and operational concepts being developed are unencumbered by existing physical and organizational infrastructures. This program really is 'starting with a clean sheet of paper'. Globalstar operations challenges can appear enormous. Clearly, assigning even a single person around the clock to monitor and control each satellite is excessive for Globalstar (it would require a staff of 200] . Even with only a single contact per orbit per satellite, data acquisitions will start or stop every 45 seconds] Although essentially identical, over time the satellites will develop their own 'personalities'and will re quire different data calibrations and levels of support. This paper discusses the Globalstar system and challenges and presents engineering concepts, system design decisions, and operations concepts which address the combined needs and concerns of satellite, ground system, and operations teams. Lessons from past missions have been applied, organizational barriers broken, partnerships formed across the mission segments, and new operations concepts developed for satellite constellation management. Control center requirements were then developed from the operations concepts.

  11. Estimation of the demand for public services communications. [market research and economic analysis for a communications satellite system

    Science.gov (United States)

    1976-01-01

    Market analyses and economic studies are presented to support NASA planning for a communications satellite system to provide public services in health, education, mobile communications, data transfer, and teleconferencing.

  12. Communications by vocoder on a mobile satellite fading channel

    Science.gov (United States)

    dal Degan, N.; Perosino, F.; Rusina, F.

    The performance of a LPC vocoder system is analyzed under various bit rate and fading errors. The error generation model developed to estimate error probability, and length of error bursts and distributions is described. Two algorithms that will improve burst are proposed. The evaluation of the spectral distance measures of the voice coding system is examined. The intelligibility, quality, and acceptability of the system are assessed using the mean opinion scores method.

  13. Downsizing Antenna Technologies for Mobile and Satellite Communications

    Science.gov (United States)

    Huang, J.; Densmore, A.; Tulintseff, A.; Jamnejad, V.

    1993-01-01

    Due to the increasing and stringent functional requirements (larger capacity, longer distances, etc.) of modern day communication systems, higher antenna gains are generally needed. This higher gain implies larger antenna size and mass which are undesirable to many systems. Consequently, downsizing antenna technology becomes one of the most critical areas for research and development efforts. Techniques to reduce antenna size can be categorized and are briefly discussed.

  14. Attitude Control Subsystem for the Advanced Communications Technology Satellite

    Science.gov (United States)

    Hewston, Alan W.; Mitchell, Kent A.; Sawicki, Jerzy T.

    1996-01-01

    This paper provides an overview of the on-orbit operation of the Attitude Control Subsystem (ACS) for the Advanced Communications Technology Satellite (ACTS). The three ACTS control axes are defined, including the means for sensing attitude and determining the pointing errors. The desired pointing requirements for various modes of control as well as the disturbance torques that oppose the control are identified. Finally, the hardware actuators and control loops utilized to reduce the attitude error are described.

  15. TYPOLOGIES OF MOBILE APPLICATIONS

    OpenAIRE

    Ion Ivan; Alin Zamfiroiu; Dragoş Palaghiţă3

    2013-01-01

    Mobile applications and their particularities are analyzed. Mobile application specific characteristics are defined. Types of applications are identified and analyzed. The paper established differences between mobile applications and mobile application categories. For each identified type the specific structures and development model are identified.

  16. Mobile Support For Logistics

    Science.gov (United States)

    2016-03-01

    mobile app . This would include all tablets and smartphones and be compatible with all mobile operating systems such as Android , iOS, BlackBerry, and... SMARTPHONE SENSORS ....................................................................12 H. DEPARTMENT OF DEFENSE MOBILE DEVICE STRATEGY...2014, p. 51. .................................................................................9 Figure 3. GCSS-MC Mobile App Architecture

  17. New empirically-derived solar radiation pressure model for GPS satellites

    Science.gov (United States)

    Bar-Sever, Y.; Kuang, D.

    2003-01-01

    Solar radiation pressure force is the second largest perturbation acting on GPS satellites, after the gravitational attraction from the Earth, Sun, and Moon. It is the largest error source in the modeling of GPS orbital dynamics.

  18. A PROPOSED HYBRID AGILE FRAMEWORK MODEL FOR MOBILE APPLICATIONS DEVELOPMENT

    Directory of Open Access Journals (Sweden)

    Ammar Khader Almasri

    2016-03-01

    Full Text Available With the increasing in mobile application systems and a high competition between companies, that led to increase in the number of mobile application projects. Mobile software development is a group of process for creating software for mobile devices with limited resources like small screen, low-power. The development of mobile applications is a big challenging because of rapidly changing business requirements and technical constraints for mobile systems. So, developers faced the challenge of a dynamic environment and the Changing of mobile application requirements. Moreover, Mobile applications should adapt appropriate software development methods that act in response efficiently to these challenges. However, at the moment, there is limited knowledge about the suitability of different software practices for the development of mobile applications. According to many researchers ,Agile methodologies was found to be most suitable for mobile development projects as they are short time, require flexibility, reduces waste and time to market. Finally, in this research we are looking for a suitable process model that conforms to the requirement of mobile application, we are going to investigate agile development methods to find a way, making the development of mobile application easy and compatible with mobile device features.

  19. Using GPS for studying pastoral mobility

    DEFF Research Database (Denmark)

    Adriansen, Hanne Kirstine

    2017-01-01

    In 1997 I embarked on a PhD to study mobility amongst nomadic pastoralists in Senegal. Previous studies had largely been conducted by anthropologists who through ethnographic fieldwork followed the nomadic pastoralists for long periods of time and did their own sketches of the movements. As a human...... as I know, the first one to use GPS for studying pastoral mobility. A total of 10 pastoralists were trained in using a GPS and asked to map their movements. This information was combined with satellite imagery on one hand and qualitative interviews on the other. This case study provides an account...... of the practical aspects of using GPS, taking the reader to the heart of some methodological issues that arose in the course of the research. The case sheds light on the particular challenges in using GPS for eliciting information about pastoral mobility. Thinking about such challenges leads to more general...

  20. Next generation mobile broadcasting

    CERN Document Server

    Gómez-Barquero, David

    2013-01-01

    Next Generation Mobile Broadcasting provides an overview of the past, present, and future of mobile multimedia broadcasting. The first part of the book-Mobile Broadcasting Worldwide-summarizes next-generation mobile broadcasting technologies currently available. This part covers the evolutions of the Japanese mobile broadcasting standard ISDB-T One-Seg, ISDB-Tmm and ISDB-TSB; the evolution of the South Korean T-DMB mobile broadcasting technology AT-DMB; the American mobile broadcasting standard ATSC-M/H; the Chinese broadcasting technologies DTMB and CMMB; second-generation digital terrestrial

  1. Satellite systems for personal applications concepts and technology

    CERN Document Server

    Richharia, Madhavendra

    2010-01-01

    Presents the concepts, technology, and role of satellite systems in support of personal applications, such as mobile and broadband communications, navigation, television, radio and multimedia broadcasting, safety of life services, etc. This book presents a novel perspective on satellite systems, reflecting the modern personal technology context, and hence a focus on the individual as end-user. The book begins by outlining key generic concepts before discussing techniques adopted in particular application areas; next, it exemplifies these techniques through discussion of state-of-art c

  2. Solar Power Satellites

    CERN Document Server

    Flournoy, Don M

    2012-01-01

    Communication satellites are a $144 billion industry. Is there any space-based industry that could possibly beat that market? 'Solar Power Satellites' shows why and how the space satellite industry will soon begin expanding its market from relaying signals to Earth to generating energy in space and delivering it to the ground as electricity. In all industrialized nations, energy demand is growing exponentially. In the developing world, the need for energy is as basic as food and water. The Sun's energy is available everywhere, and it is non-polluting. As business plans demonstrate its technical feasibility, commercial potential, and environmental acceptability, every country on Earth will look to space for the power it needs.

  3. Geostationary satellites collocation

    CERN Document Server

    Li, Hengnian

    2014-01-01

    Geostationary Satellites Collocation aims to find solutions for deploying a safe and reliable collocation control. Focusing on the orbital perturbation analysis, the mathematical foundations for orbit and control of the geostationary satellite are summarized. The mathematical and physical principle of orbital maneuver and collocation strategies for multi geostationary satellites sharing with the same dead band is also stressed. Moreover, the book presents some applications using the above algorithms and mathematical models to help readers master the corrective method for planning station keeping maneuvers. Engineers and scientists in the fields of aerospace technology and space science can benefit from this book. Hengnian Li is the Deputy Director of State Key Laboratory of Astronautic Dynamics, China.

  4. ESA's satellite communications programme

    Science.gov (United States)

    Bartholome, P.

    1985-02-01

    The developmental history, current status, and future plans of the ESA satellite-communications programs are discussed in a general survey and illustrated with network diagrams and maps. Consideration is given to the parallel development of national and European direct-broadcast systems and telecommunications networks, the position of the European space and electronics industries in the growing world market, the impact of technological improvements (both in satellite systems and in ground-based networks), and the technological and commercial advantages of integrated space-terrestrial networks. The needs for a European definition of the precise national and international roles of satellite communications, for maximum speed in implementing such decisions (before the technology becomes obsolete), and for increased cooperation and standardization to assure European equipment manufacturers a reasonable share of the market are stressed.

  5. AVS on satellite

    Science.gov (United States)

    Zhao, Haiwu; Wang, Guozhong; Hou, Gang

    2005-07-01

    AVS is a new digital audio-video coding standard established by China. AVS will be used in digital TV broadcasting and next general optical disk. AVS adopted many digital audio-video coding techniques developed by Chinese company and universities in recent years, it has very low complexity compared to H.264, and AVS will charge very low royalty fee through one-step license including all AVS tools. So AVS is a good and competitive candidate for Chinese DTV and next generation optical disk. In addition, Chinese government has published a plan for satellite TV signal directly to home(DTH) and a telecommunication satellite named as SINO 2 will be launched in 2006. AVS will be also one of the best hopeful candidates of audio-video coding standard on satellite signal transmission.

  6. Satellite Control Laboratory

    DEFF Research Database (Denmark)

    Wisniewski, Rafal; Bak, Thomas

    2001-01-01

    The Satellite Laboratory at the Department of Control Engineering of Aalborg University (SatLab) is a dynamic motion facility designed for analysis and test of micro spacecraft. A unique feature of the laboratory is that it provides a completely gravity-free environment. A test spacecraft...... is suspended on an air bearing, and rotates freely in 3 degrees of freedom. In order to avoid any influence of the gravitational force the centre of mass of the satellite is placed in the geometric centre of the air bearing by an automatic balancing system. The test spacecraft is equipped with a three......-axis magnetometer, three piezoelectric gyros, and four reaction wheels in a tetrahedron configuration. The operation of the spacecraft is fully autonomous. The data flow between the transducers and the onboard computer placed physically outside the satellite is provided by a radio link. The purpose...

  7. Mobile platform security

    CERN Document Server

    Asokan, N; Dmitrienko, Alexandra

    2013-01-01

    Recently, mobile security has garnered considerable interest in both the research community and industry due to the popularity of smartphones. The current smartphone platforms are open systems that allow application development, also for malicious parties. To protect the mobile device, its user, and other mobile ecosystem stakeholders such as network operators, application execution is controlled by a platform security architecture. This book explores how such mobile platform security architectures work. We present a generic model for mobile platform security architectures: the model illustrat

  8. ON MOBILE MESH NETWORKS

    OpenAIRE

    2015-01-01

    With the advances in mobile computing technologies and the growth of the Net, mobile mesh networks are going through a set of important evolutionary steps. In this paper, we survey architectural aspects of mobile mesh networks and their use cases and deployment models. Also, we survey challenging areas of mobile mesh networks and describe our vision of promising mobile services. This paper presents a basic introductory material for Masters of Open Information Technologies Lab, interested in m...

  9. LTE mobile network technology

    OpenAIRE

    Sladič, Klemen

    2012-01-01

    The main purpose of this thesis is an introduction to long term evolution of fourth generation mobile networks based on LTE mobile network standard. Fourth generation mobile networks are currently one of the most developed technology in the world of mobile communications and are somewhere already available for commercial use. At the beginning is a short history of mobile networks evolution, for easier understanding. In the history you can find information from first researches of magnetic...

  10. MOBILE AGENT: EMERGING TECHNOLOGY

    OpenAIRE

    RAJGURU P. V. DR. DESHMUKH S. D

    2011-01-01

    Mobile agent technology has been promoted as an emerging technology that makes it much easier to design, implement, and maintain distributed systems, introduction to basic concepts of mobile agents like agent mobility, agent types and places and agent communication. Then benefits of the usage of mobile agents are summarized and illustrated by selected applications. The next section lists requirements and desirable properties for mobile agent languages and systems. We study the main features, ...

  11. GPS satellite surveying

    CERN Document Server

    Leick, Alfred; Tatarnikov, Dmitry

    2015-01-01

    THE MOST COMPREHENSIVE, UP-TO-DATE GUIDE ON GPS TECHNOLOGY FOR SURVEYING Three previous editions have established GPS Satellite Surveying as the definitive industry reference. Now fully updated and expanded to reflect the newest developments in the field, this Fourth Edition features cutting-edge information on GNSS antennas, precise point positioning, real-time relative positioning, lattice reduction, and much more. Expert authors examine additional tools and applications, offering complete coverage of geodetic surveying using satellite technologies. The past decade has seen a major evolut

  12. Declassified intelligence satellite photographs

    Science.gov (United States)

    ,

    1998-01-01

    Recently declassified photographs from spy satellites are an important addition to the record of the Earth?s land surface held by the U.S. Geological Survey (USGS). More than 800,000 high-resolution photos taken between 1959 through 1972 were made available by Executive Order of the President. The collection is held at the USGS EROS Data Center, near Sioux Falls, S. Dak., and are offered for public sale. For some purposes in earth science studies, these photos extend the record of changes in the land surface another decade back in time from the advent of the Landsat earth-observing satellite program.

  13. Oceanography from satellites

    Science.gov (United States)

    Wilson, W. S.

    1981-01-01

    It is pointed out that oceanographers have benefited from the space program mainly through the increased efficiency it has brought to ship operations. For example, the Transit navigation system has enabled oceanographers to compile detailed maps of sea-floor properties and to more accurately locate moored subsurface instrumentation. General descriptions are given of instruments used in satellite observations (altimeter, color scanner, infrared radiometer, microwave radiometer, scatterometer, synthetic aperture radar). It is pointed out that because of the large volume of data that satellite instruments generate, the development of algorithms for converting the data into a form expressed in geophysical units has become especially important.

  14. Satellite oceanography - The instruments

    Science.gov (United States)

    Stewart, R. H.

    1981-01-01

    It is pointed out that no instrument is sensitive to only one oceanographic variable; rather, each responds to a combination of atmospheric and oceanic phenomena. This complicates data interpretation and usually requires that a number of observations, each sensitive to somewhat different phenomena, be combined to provide unambiguous information. The distinction between active and passive instruments is described. A block diagram illustrating the steps necessary to convert data from satellite instruments into oceanographic information is included, as is a diagram illustrating the operation of a radio-frequency radiometer. Attention is also given to the satellites that carry the various oceanographic instruments.

  15. Integrated Satellite-HAP Systems

    DEFF Research Database (Denmark)

    Cianca, Ernestina; De Sanctis, Mauro; De Luise, Aldo

    2005-01-01

    for an efficient hybrid terrestrial-satellite communication system. Two integrated HAP-satellite scenarios are presented, in which the HAP is used to overcome some of the shortcomings of satellite- based communications. Moreover, it is shown that the integration of HAPs with satellite systems can be used......Thus far, high-altitude platform (HAP)-based systems have been mainly conceived as an alternative to satellites for complementing the terrestrial network. This article aims to show that HAP should no longer be seen as a competitor technology by investors of satellites, but as a key element...

  16. Recent Korean R&D in Satellite Communications

    Science.gov (United States)

    Lee, Ho-Jin; Kim, Jae Moung; Lee, Byung-Seub; Lee, Han; Ryoo, Jang-Soo

    The R&D in satellite communications in Korea has been driven mainly by KCC (Korea Communications Commission) but in a small scale compared to Korea space development program organized by MEST (Ministry of Education, Science and Technology). Public and civilian satcom sector R&D has been led mainly by ETRI with small/medium companies contrary to rare investment in private sector while military sector R&D has been orchestrated by ADD with defense industry. By the COMS (Communication, Ocean and Meteorological Satellite) experimental Ka-band payload, Korea pursues a space qualification of own technology for national infrastructure evolution as well as industrialization of space R&D results. Once COMS launched and space qualified in 2009, subsequent application experiments and new technology R&D like UHDTV will entail service and industry promotion. The payload technology is expected for the next Korean commercial satellites or for new OBP satellites. The COMS ground control system and GNSS ground station technologies are under development for COMS operation and enhanced GNSS services along with advent of Galileo respectively. Satellite broadband mobile VSAT based on DVB-S2/RCS (+M) and low profile tracking antennas have been developed for trains, ships, and planes. While APSI is developing GMR-1 based Thuraya handset functions, ETRI is designing IMT-Advanced satellite radio interface for satellite and terrestrial dual-mode handheld communication system like Japanese STICS, with universities' satellite OFDM researches. A 21GHz Ka-band higher-availability scalable HD broadcasting technology and SkyLife's hybrid satellite IPTV technology are being developed. In near term Korea will extend R&D programs to upgrade the space communication infrastructure for universal access to digital opportunity and safer daily life from disaster, and to promote space green IT industrialization, national security, and space resources sovereign. Japanese stakeholders are invited to establish

  17. Equilibria of a charged artificial satellite subject to gravitational and Lorentz torques

    CERN Document Server

    Abdel-Aziz, Yehia A

    2014-01-01

    Attitude Dynamics of a rigid artificial satellite subject to gravity gradient and Lorentz torques in a circular orbit is considered. Lorentz torque is developed on the basis of the electrodynamic effects of the Lorentz force acting on the charged satellite's surface. We assume that the satellite is moving in Low Earth Orbit (LEO) in the geomagnetic field which is considered as a dipole model. Our model of the torque due to the Lorentz force is developed for a general shape of artificial satellite, and the nonlinear differential equations of Euler are used to describe its attitude orientation. All equilibrium positions are determined and {their} existence conditions are obtained. The numerical results show that the charge $q$ and radius $\\rho_0$ of the charged center of satellite provide a certain type of semi passive control for the attitude of satellite. The technique for such kind of control would be to increase or decrease the electrostatic radiation screening of the satellite. The results {obtained} confi...

  18. Satellite Technology Contribution to Water and Food Security

    Science.gov (United States)

    Brown, Molly E.

    2010-01-01

    This slide presentation reviews the issue of supplies of food, the relationship to food security, the ability of all people to attain sufficient food for an active and healthy life, and the ability to use satellite technology and remote sensing to assist with planning and act as an early warning system.

  19. Integrated Cryogenic Satellite Communications Cross-Link Receiver Experiment

    Science.gov (United States)

    Romanofsky, R. R.; Bhasin, K. B.; Downey, A. N.; Jackson, C. J.; Silver, A. H.; Javadi, H. H. S.

    1995-01-01

    An experiment has been devised which will validate, in space, a miniature, high-performance receiver. The receiver blends three complementary technologies; high temperature superconductivity (HTS), pseudomorphic high electron mobility transistor (PHEMT) monolithic microwave integrated circuits (MMIC), and a miniature pulse tube cryogenic cooler. Specifically, an HTS band pass filter, InP MMIC low noise amplifier, HTS-sapphire resonator stabilized local oscillator (LO), and a miniature pulse tube cooler will be integrated into a complete 20 GHz receiver downconverter. This cooled downconverter will be interfaced with customized signal processing electronics and integrated onto the space shuttle's 'HitchHiker' carrier. A pseudorandom data sequence will be transmitted to the receiver, which is in low Earth orbit (LEO), via the Advanced Communication Technology Satellite (ACTS) on a 20 GHz carrier. The modulation format is QPSK and the data rate is 2.048 Mbps. The bit error rate (BER) will be measured in situ. The receiver is also equipped with a radiometer mode so that experiment success is not totally contingent upon the BER measurement. In this mode, the receiver uses the Earth and deep space as a hot and cold calibration source, respectively. The experiment closely simulates an actual cross-link scenario. Since the receiver performance depends on channel conditions, its true characteristics would be masked in a terrestrial measurement by atmospheric absorption and background radiation. Furthermore, the receiver's performance depends on its physical temperature, which is a sensitive function of platform environment, thermal design, and cryocooler performance. This empirical data is important for building confidence in the technology.

  20. The Coverage Analysis for Low Earth Orbiting Satellites at Low Elevation

    Directory of Open Access Journals (Sweden)

    Shkelzen Cakaj

    2014-07-01

    Full Text Available Low Earth Orbit (LEO satellites are used for public networking and for scientific purposes. Communication via satellite begins when the satellite is positioned in its orbital position. Ground stations can communicate with LEO satellites only when the satellite is in their visibility region. The duration of the visibility and the communication vary for each LEO satellite pass over the station, since LEO satellites move too fast over the Earth. The satellite coverage area is defined as a region of the Earth where the satellite is seen at a minimum predefined elevation angle. The satellite’s coverage area on the Earth depends on orbital parameters. The communication under low elevation angles can be hindered by natural barriers. For safe communication and for savings within a link budget, the coverage under too low elevation is not always provided. LEO satellites organized in constellations act as a convenient network solution for real time global coverage. Global coverage model is in fact the complementary networking process of individual satellite’s coverage. Satellite coverage strongly depends on elevation angle. To conclude about the coverage variation for low orbiting satellites at low elevation up to 10º, the simulation for attitudes from 600km to 1200km is presented through this paper.

  1. New dynamic routing algorithm based on MANET in LEO/MEO satellite network

    Institute of Scientific and Technical Information of China (English)

    LI Zhe; LI Dong-ni; WANG Guang-xing

    2006-01-01

    The features of low earth orbit/medium earth orbit (LEO/MEO) satellite networks routing algorithm based on inter-satellite link are analyzed and the similarities between satellite networks and mobile Ad Hoc network (MANET) are pointed out.The similar parts in MANET routing protocol are used in the satellite network for reference.A new dynamic routing algorithm based on MANET in LEO/MEO satellite networks,which fits for the LEO/MEO satellite communication system,is proposed.At the same time,the model of the algorithm is simulated and features are analyzed.It is shown that the algorithm has strong adaptability.It can give the network high autonomy,perfect function,low system overhead and great compatibility.

  2. Design and Implementation of Anti Lost Bluetooth Low Energy Mobile Device for Mobile Phone

    Directory of Open Access Journals (Sweden)

    Prajakta S. Chavan

    2014-05-01

    Full Text Available Today mobile phone like smart phone, tablet are very costly ranging from 300 USD to 600 USD , to avoid them to get forget at any social places, we can have mobile device(gadget which will warn us (beepthis device is left back .To make commercialize product which will act as mobile phone watchmen, with specification and characteristic like smallest device foot print, comfortable to carry along, ultra low power consumption to increase battery life and to avoid frequent charging, ultra low Sleep currents and efficient performance. As per this specification we will develop a mobile device (gadget which will connect to mobile phone by Bluetooth connectivity if this gadget will go beyond 4 to 6 meters gadget will beep loud when Bluetooth connectivity breaks.

  3. Testing Lorentz invariance of dark matter with satellite galaxies

    Science.gov (United States)

    Bettoni, Dario; Nusser, Adi; Blas, Diego; Sibiryakov, Sergey

    2017-05-01

    We develop the framework for testing Lorentz invariance in the dark matter sector using galactic dynamics. We consider a Lorentz violating (LV) vector field acting on the dark matter component of a satellite galaxy orbiting in a host halo. We introduce a numerical model for the dynamics of satellites in a galactic halo and for a galaxy in a rich cluster to explore observational consequences of such an LV field. The orbital motion of a satellite excites a time dependent LV force which greatly affects its internal dynamics. Our analysis points out key observational signatures which serve as probes of LV forces. These include modifications to the line of sight velocity dispersion, mass profiles and shapes of satellites. With future data and a more detailed modeling these signatures can be exploited to constrain a new region of the parameter space describing the LV in the dark matter sector.

  4. Synthetically adaptive robust filtering for satellite orbit determination

    Institute of Scientific and Technical Information of China (English)

    YANG; Yuanxi

    2004-01-01

    The quality of the satellite orbit determination is rested on the knowledge of perturbing forces acting on the satellite and stochastic properties of the observations, and the ability of controlling various kinds of errors. After a brief discussion on the dynamic and geometric orbit determinations, Sage adaptive filtering and robust filtering are reviewed. A new synthetically adaptive robust filtering based on a combination of robust filtering and Sage filtering is developed. It is shown, by derivations and calculations, that the synthetically adaptive robust filtering for orbit determination is not only robust but also simple in calculation. It controls the effects of the outliers of tracking observations and the satellite dynamical disturbance on the parameter estimates of the satellite orbit.

  5. Charging of mobile services by mobile payment reference model

    OpenAIRE

    Pousttchi, Key; Wiedemann, Dietmar Georg

    2005-01-01

    The purpose of the paper is to analyze mobile payments in the mobile commerce scenario. Therefore, we first classify the mobile payment in the mobile commerce scenario by explaining general offer models, charging concepts, and intermediaries. Second, we describe the mobile payment reference model, especially, the mobile payment reference organization model and different mobile payment standard types. Finally, we conclude our findings.

  6. Abrechnung mobiler Dienste im Mobile-Payment-Referenzmodell

    OpenAIRE

    Pousttchi, Key; Wiedemann, Dietmar Georg

    2005-01-01

    The purpose of the paper is to analyze mobile payments in the mobile commerce scenario. Therefore, we first classify the mobile payment in the mobile commerce scenario by explaining general offer models, charging concepts, and intermediaries. Second, we describe the mobile payment reference model, especially, the mobile payment reference organization model and different mobile payment standard types. Finally, we conclude our findings.

  7. Abrechnung mobiler Dienste im Mobile-Payment-Referenzmodell

    OpenAIRE

    Pousttchi, Key; Wiedemann, Dietmar Georg

    2005-01-01

    The purpose of the paper is to analyze mobile payments in the mobile commerce scenario. Therefore, we first classify the mobile payment in the mobile commerce scenario by explaining general offer models, charging concepts, and intermediaries. Second, we describe the mobile payment reference model, especially, the mobile payment reference organization model and different mobile payment standard types. Finally, we conclude our findings.

  8. Assessing the Impact of Earth Radiation Pressure Acceleration on Low-Earth Orbit Satellites

    Science.gov (United States)

    Vielberg, Kristin; Forootan, Ehsan; Lück, Christina; Kusche, Jürgen; Börger, Klaus

    2017-04-01

    The orbits of satellites are influenced by several external forces. The main non-gravitational forces besides thermospheric drag, acting on the surface of satellites, are accelerations due to the Earth and Solar Radiation Pres- sure (SRP and ERP, respectively). The sun radiates visible and infrared light reaching the satellite directly, which causes the SRP. Earth also emits and reflects the sunlight back into space, where it acts on satellites. This is known as ERP acceleration. The influence of ERP increases with decreasing distance to the Earth, and for low-earth orbit (LEO) satellites ERP must be taken into account in orbit and gravity computations. Estimating acceler- ations requires knowledge about energy emitted from the Earth, which can be derived from satellite remote sensing data, and also by considering the shape and surface material of a satellite. In this sensitivity study, we assess ERP accelerations based on different input albedo and emission fields and their modelling for the satellite missions Challenging Mini-Satellite Payload (CHAMP) and Gravity Recovery and Climate Experiment (GRACE). As input fields, monthly 1°x1° products of Clouds and the Earth's Radiant En- ergy System (CERES), L3 are considered. Albedo and emission models are generated as latitude-dependent, as well as in terms of spherical harmonics. The impact of different albedo and emission models as well as the macro model and the altitude of satellites on ERP accelerations will be discussed.

  9. Mobility and Handoff Management in Wireless Networks

    CERN Document Server

    Sen, Jaydip

    2010-01-01

    With the increasing demands for new data and real-time services, wireless networks should support calls with different traffic characteristics and different Quality of Service (QoS)guarantees. In addition, various wireless technologies and networks exist currently that can satisfy different needs and requirements of mobile users. Since these different wireless networks act as complementary to each other in terms of their capabilities and suitability for different applications, integration of these networks will enable the mobile users to be always connected to the best available access network depending on their requirements. This integration of heterogeneous networks will, however, lead to heterogeneities in access technologies and network protocols. To meet the requirements of mobile users under this heterogeneous environment, a common infrastructure to interconnect multiple access networks will be needed. In this chapter, the design issues of a number of mobility management schemes have been presented. Eac...

  10. Man-made Satellites

    Institute of Scientific and Technical Information of China (English)

    郝昌明

    2005-01-01

    If you watch the sky about an hour after the sun goes down, you may see some “moving stars”. But they're not real stars. They're manmade satellites (卫星). And the biggest of all is the International Space Station (ISS国际空间站).

  11. Observations of artificial satellites

    Directory of Open Access Journals (Sweden)

    A. MAMMANO

    1964-06-01

    Full Text Available The following publication gives the results of photographic
    observations of artificial satellites made at Asiago during the second
    and third year of this programme. The fixed camera technique and that
    with moving film (the latter still in its experimental stage have been used.

  12. Experimental Satellite Quantum Communications.

    Science.gov (United States)

    Vallone, Giuseppe; Bacco, Davide; Dequal, Daniele; Gaiarin, Simone; Luceri, Vincenza; Bianco, Giuseppe; Villoresi, Paolo

    2015-07-24

    Quantum communication (QC), namely, the faithful transmission of generic quantum states, is a key ingredient of quantum information science. Here we demonstrate QC with polarization encoding from space to ground by exploiting satellite corner cube retroreflectors as quantum transmitters in orbit and the Matera Laser Ranging Observatory of the Italian Space Agency in Matera, Italy, as a quantum receiver. The quantum bit error ratio (QBER) has been kept steadily low to a level suitable for several quantum information protocols, as the violation of Bell inequalities or quantum key distribution (QKD). Indeed, by taking data from different satellites, we demonstrate an average value of QBER=4.6% for a total link duration of 85 s. The mean photon number per pulse μ_{sat} leaving the satellites was estimated to be of the order of one. In addition, we propose a fully operational satellite QKD system by exploiting our communication scheme with orbiting retroreflectors equipped with a modulator, a very compact payload. Our scheme paves the way toward the implementation of a QC worldwide network leveraging existing receivers.

  13. Perception via satellite

    Science.gov (United States)

    Robinove, Charles J.

    1970-01-01

    The earth resources observation satellite (EROS) program in the Department of the Interior is intended to gather and use data from satellites and aircraft on natural and man-made features of the earth's surface. Earth resources technology satellite will provide the EROS program with data for use in dealing with natural resource problems and understanding the interaction between man and the environment. Applications will include studies of tectonic features, hydrologic problems, location of fish schools, determination of the conditions of range land, mapping land use for urban planning, studies of erosion and change along coastlines and major streams, and inventories of land use and land forms. In addition, the ERTS data may be used for detecting forest and crop diseases and inventorying crops. The ERTS satellite will be in a polar, sun-synchronous orbit so that each point on the earth's surface will be sensed every 17 to 20 days, at the same time of day. Multispectral photography is being investigated for its usefulness in hydrology. Side-looking airborne radar has not yet been widely used in hydrologic studies, although it is an excellent tool for all-weather, day or night, coverage of large areas. Other techniques being investigated include passive microwave radiometry, ultraviolet and visible stimulated luminescence, and absorption spectroscopy.

  14. Satellite Photometric Error Determination

    Science.gov (United States)

    2015-10-18

    of nearly specular reflections from most solar panels. Our primary purpose in presenting these two plots is to demonstrate the usefulness of...than a transformation for stars because the spectral energy distribution of satellites can change with phase angle and is subject to specular

  15. Creating Better Satellite Conferences.

    Science.gov (United States)

    Horner, Tommy

    1998-01-01

    Presents four ways to improve broadcasts of company satellite conferences, including creative site selection (using facilities at educational institutions rather than hotel rooms); creative programming (using graphics and other interruptions to break up lectures or speeches); creative crew selection; and creative downlink site activities (to…

  16. Ocean surveillance satellites

    Science.gov (United States)

    Laurent, D.

    Soviet and U.S. programs involving satellites for surveillance of ships and submarines are discussed, considering differences in approaches. The Soviet program began with the Cosmos 198 in 1967 and the latest, the Cosmos 1400 series, 15 m long and weighing 5 tons, carry radar for monitoring ships and a nuclear reactor for a power supply. Other Soviet spacecraft carrying passive microwave sensors and ion drives powered by solar panels have recently been detonated in orbit for unknown reasons. It has also been observed that the Soviet satellites are controlled in pairs, with sequential orbital changes for one following the other, and both satellites then overflying the same points. In contrast, U.S. surveillance satellites have been placed in higher orbits, thus placing greater demands on the capabilities of the on-board radar and camera systems. Project White Cloud and the Clipper Bow program are described, noting the continued operation of the White Cloud spacecraft, which are equipped to intercept radio signals from surface ships. Currently, the integrated tactical surveillance system program has completed its study and a decision is expected soon.

  17. OMV With Satellite

    Science.gov (United States)

    1986-01-01

    This 1986 artist's concept shows the Orbital Maneuvering Vehicle (OMV) towing a satellite. As envisioned by Marshall Space Flight Center plarners, the OMV would be a remotely-controlled free-flying space tug which would place, rendezvous, dock, and retrieve orbital payloads.

  18. Advances in satellite oceanography

    Science.gov (United States)

    Brown, O. B.; Cheney, R. E.

    1983-01-01

    Technical advances and recent applications of active and passive satellite remote sensing techniques to the study of oceanic processes are summarized. The general themes include infrared and visible radiometry, active and passive microwave sensors, and buoy location systems. The surface parameters of sea surface temperature, windstream, sea state, altimetry, color, and ice are treated as applicable under each of the general methods.

  19. Cibola flight experiment satellite

    Science.gov (United States)

    Davies, P.; Liddle, Doug; Paffett, John; Sweeting, Martin; Curiel, A.; Sun, Wei; Eves, Stuart

    2004-11-01

    In order to achieve an "economy of scale" with respect to payload capacity the major trend in telecommunications satellites is for larger and larger platforms. With these large platforms the level of integration between platform and payload is increasing leading to longer delivery schedules. The typical lifecycle for procurement of these large telecommunications satellites is now 3-6 years depending on the level of non-recurring engineering needed. Surrey Satellite Technology Ltd (SSTL) has designed a low-cost platform aimed at telecommunications and navigation applications. SSTL's Geostationary Minisatellite Platform (GMP) is a new entrant addressing the lower end of the market with payloads up to 250kg requiring less than 1.5 kW power. The British National Space Centre through the MOSAIC Small Satellite Initiative supported the development of GMP. The main design goals for GMP are low-cost for the complete mission including launch and operations and a platform allowing flexible payload accommodation. GMP is specifically designed to allow rapid development and deployment with schedules typically between 1 and 2 years from contract signature to flight readiness. GMP achieves these aims by a modular design where the level of integration between the platform and payload is low. The modular design decomposes the satellite into three major components - the propulsion bay, the avionics bay and the payload module. Both the propulsion and avionics bays are reusable, largely unchanged, and independent of the payload configuration. Such a design means that SSTL or a 3rd party manufacturer can manufacture the payload in parallel to the platform with integration taking place quite late in the schedule. In July 2003 SSTL signed a contract for ESA's first Galileo navigation satellite known as GSTBV2/A. The satellite is based on GMP and ESA plan to launch it into a MEO orbit late in 2005. The second flight of GMP is likely to be in 2006 carrying a geostationary payload

  20. DVB-S Signal Tracking Techniques for Mobile Phased Arrays

    NARCIS (Netherlands)

    Blom, Koen C.H.; Burgwal, van de Marcel D.; Rovers, Kenneth C.; Kokkeler, André B.J.; Smit, Gerard J.M.

    2010-01-01

    Abstract—A system that uses adaptive beamforming techniques for mobile Digital Video Broadcasting Satellite (DVB-S) reception is proposed in this paper. The purpose is to enable DVB-S reception in moving vehicles. Phased arrays are able to electronically track the desired signal during dynamic behav

  1. Mobility Charters and Manifestos

    DEFF Research Database (Denmark)

    Jensen, Ole B.

    2010-01-01

    the ‘mobility turn’ that mobility is much more than movement from A to B. Seeing the cultural dimension as well as the underpinning power plays of normative mobility discourses opens up the reflection about imagined futures and imagined mobile subjects. Theoretically the paper bridges discourse studies......This paper explore a number of different cases of articulating notions of ‘correct’ mobility behavior and practice by looking into charters, manifestos and codes of mobility regulation. Within such discourses of ‘correct mobility’ more or less subtle expressions of power as well as normative...... and ethical positions on mobility prevail. Such ‘imagined correct mobility behavior’ are drawing on larger issues of societal change that need to be brought out in a critical analysis and discussion reflecting the attempts to control, design and orchestrate mobility patterns. The paper therefore argues within...

  2. Mobility Charters and Manifestos

    DEFF Research Database (Denmark)

    Jensen, Ole B.

    2010-01-01

    and ethical positions on mobility prevail. Such ‘imagined correct mobility behavior’ are drawing on larger issues of societal change that need to be brought out in a critical analysis and discussion reflecting the attempts to control, design and orchestrate mobility patterns. The paper therefore argues within......This paper explore a number of different cases of articulating notions of ‘correct’ mobility behavior and practice by looking into charters, manifestos and codes of mobility regulation. Within such discourses of ‘correct mobility’ more or less subtle expressions of power as well as normative...... the ‘mobility turn’ that mobility is much more than movement from A to B. Seeing the cultural dimension as well as the underpinning power plays of normative mobility discourses opens up the reflection about imagined futures and imagined mobile subjects. Theoretically the paper bridges discourse studies...

  3. Children's velo-mobility

    DEFF Research Database (Denmark)

    Carstensen, Trine Agervig; Nielsen, Thomas Sick; Olafsson, Anton Stahl

    2014-01-01

    Sustainable mobilities play a dominate role in low carbon futures and cycling is an integral element. Children are heirs of transport cultures and crucial for future sustainable mobility. Moreover cycling is important for children’s independent mobility and geographical experience. Dominating app...... the paper inform a discussion of urban planning and transport policy measures important for stabilizing sustainable mobility.......Sustainable mobilities play a dominate role in low carbon futures and cycling is an integral element. Children are heirs of transport cultures and crucial for future sustainable mobility. Moreover cycling is important for children’s independent mobility and geographical experience. Dominating...... approaches in transport research, including cycling, understand travel behaviour individualistic and lack to grasp the relational complexities, which are inevitable when considering children’s mobilities. Furthermore has children’s cycling largely been studied as independent mobility and active school travel...

  4. Defense Meteorological Satellite Program (DMSP)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The Defense Meteorological Satellite Program (DMSP) satellites collect visible and infrared cloud imagery as well as monitoring the atmospheric, oceanographic,...

  5. Mobile Satellite Reception with a Virtual Satellite Dish based on a Reconfigurable Multi-Processor Architecture

    NARCIS (Netherlands)

    Burgwal, van de M.D.; Rovers, K.C.; Blom, K.C.H.; Kokkeler, A.B.J.; Smit, G.J.M.

    2011-01-01

    Traditionally, mechanically steered dishes or analog phased array beamforming systems have been used for radio frequency receivers, where strong directivity and high performance were much more important than low-cost requirements. Real-time controlled digital phased array beamforming could not be re

  6. DFH Satellite Co.,Ltd.

    Institute of Scientific and Technical Information of China (English)

    SunQing

    2004-01-01

    DFH Satellite Co.,Ltd. is a hi-tech enterprise founded and sponsored by China Aerospace Science and Technology Corporation(CASC) and one of CASC subsidiaries,China Academy of Space Technology (CAST). The company is mainly engaged in the research and development of small satellites and micro-satellites, Osystem designs and product development for satellite application projects as well as the international exchanges and cooperation.

  7. Head First Mobile Web

    CERN Document Server

    Gardner, Lyza; Grigsby, Jason

    2011-01-01

    Despite the huge number of mobile devices and apps in use today, your business still needs a website. You just need it to be mobile. Head First Mobile Web walks you through the process of making a conventional website work on a variety smartphones and tablets. Put your JavaScript, CSS media query, and HTML5 skills to work-then optimize your site to perform its best in the demanding mobile market. Along the way, you'll discover how to adapt your business strategy to target specific devices. Navigate the increasingly complex mobile landscapeTake both technical and strategic approaches to mobile

  8. Mobile Portal Implementation Strategy

    DEFF Research Database (Denmark)

    Gao, Ping; Damsgaard, Jan

    2005-01-01

    Mobile portal plays an important role in mobile commerce market. Current literature focuses on static analysis on the value chain of mobile portals. This article provides a dynamic perspective on mobile portal strategy. Drawing upon network economics, we describe mobile portal implementation...... as a fourphase process. In different phase, a portal provider has various challenges to overcome and adopt diverse strategies, and correspondingly the regulator has different foci. The conceptual framework proposed in this article offers a basis for further analyses on the market dynamics of mobile commerce......, and can be generalized to studying other networked technologies...

  9. MobiLED: mobile-led and leading via mobile

    CSIR Research Space (South Africa)

    Ford, M

    2009-03-01

    Full Text Available ” of these devices. MobilED (Mobile EDucation) started as a 3-year initiative in 2006 which aimed to take advantage of the cell phone as the only effective technology device in the hands of African children and youth. Although cell phones currently do not play...-and-SMS-only models through to multimedia and smartphones; 2. GSM/GPRS/3G/Bluetooth communication channels; 3. Wikipedia: The Free Encyclopedia; 4. Social Software: MediaWiki, blogs; instant messaging; 5. Open Source Language technologies: Speech interfaces...

  10. Telelibrary: Library Services via Satellite.

    Science.gov (United States)

    Liu, Rosa

    1979-01-01

    Investigates the provision of library services via satellite, explains briefly the operation and advantages of communication satellites, and discusses the various telecommunications equipment and services which, when coupled with satellite transmission, will enhance library activities. Demand trend projections for telecommunications services…

  11. Satellite Aerodynamics and Density Determination from Satellite Dynamic Response

    Science.gov (United States)

    Karr, G. R.

    1972-01-01

    The aerodynamic drag and lift properties of a satellite are first expressed as a function of two parameters associated with gas-surface interaction at the satellite surface. The dynamic response of the satellite as it passes through the atmosphere is then expressed as a function of the two gas-surface interaction parameters, the atmospheric density, the satellite velocity, and the satellite orientation to the high speed flow. By proper correlation of the observed dynamic response with the changing angle of attack of the satellite, it is found that the two unknown gas-surface interaction parameters can be determined. Once the gas-surface interaction parameters are known, the aerodynamic properties of the satellite at all angles of attack are also determined.

  12. Mobile robot sense net

    Science.gov (United States)

    Konolige, Kurt G.; Gutmann, Steffen; Guzzoni, Didier; Ficklin, Robert W.; Nicewarner, Keith E.

    1999-08-01

    Mobile robot hardware and software is developing to the point where interesting applications for groups of such robots can be contemplated. We envision a set of mobots acting to map and perform surveillance or other task within an indoor environment (the Sense Net). A typical application of the Sense Net would be to detect survivors in buildings damaged by earthquake or other disaster, where human searchers would be put a risk. As a team, the Sense Net could reconnoiter a set of buildings faster, more reliably, and more comprehensibly than an individual mobot. The team, for example, could dynamically form subteams to perform task that cannot be done by individual robots, such as measuring the range to a distant object by forming a long baseline stereo sensor form a pari of mobots. In addition, the team could automatically reconfigure itself to handle contingencies such as disabled mobots. This paper is a report of our current progress in developing the Sense Net, after the first year of a two-year project. In our approach, each mobot has sufficient autonomy to perform several tasks, such as mapping unknown areas, navigating to specific positions, and detecting, tracking, characterizing, and classifying human and vehicular activity. We detail how some of these tasks are accomplished, and how the mobot group is tasked.

  13. Exploring the Mobility of Mobile Phone Users

    CERN Document Server

    Csáji, Balázs Cs; Traag, V A; Delvenne, Jean-Charles; Huens, Etienne; Van Dooren, Paul; Smoreda, Zbigniew; Blondel, Vincent D

    2013-01-01

    Mobile phone datasets allow for the analysis of human behavior on an unprecedented scale. The social network, temporal dynamics and mobile behavior of mobile phone users have often been analyzed independently from each other using mobile phone datasets. In this article, we explore the connections between various features of human behavior extracted from a large mobile phone dataset. Our observations are based on the analysis of communication data of 100000 anonymized and randomly chosen individuals in a dataset of communications in Portugal. We show that clustering and principal component analysis allow for a significant dimension reduction with limited loss of information. The most important features are related to geographical location. In particular, we observe that most people spend most of their time at only a few locations. With the help of clustering methods, we then robustly identify home and office locations and compare the results with official census data. Finally, we analyze the geographic spread ...

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

    Science.gov (United States)

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

    1993-01-01

    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.

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

    Science.gov (United States)

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

    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.

  16. Enhanced Image Analysis Using Cached Mobile Robots

    Directory of Open Access Journals (Sweden)

    Kabeer Mohammed

    2012-11-01

    Full Text Available In the field of Artificial intelligence Image processing plays a vital role in Decision making .Now a day’s Mobile robots work as a Network sharing Centralized Data base.All Image inputs are compared against this database and decision is made.In some cases the Centralized database is in other side of the globe and Mobile robots compare Input image through satellite link this sometime results in delays in decision making which may result in castrophe.This Research paper is about how to make image processing in mobile robots less time consuming and fast decision making.This research paper compares search techniques employed currently and optimum search method which we are going to state.Now a days Mobile robots are extensively used in environments which are dangerous to human beings.In this dangerous situations quick Decision making makes the difference between Hit and Miss this can also results in Day to day tasks performed by Mobile robots Successful or Failure.

  17. Performance of TCP Vegas, Bic and Reno Congestion Control Algorithms on Iridium Satellite Constellations

    Directory of Open Access Journals (Sweden)

    M.Nirmala

    2012-11-01

    Full Text Available Satellite networking is different from wired or wireless networks. The behavior and the performance of TCP/IP in normal wireless network as well as in wired network are different from one another. The TCP/IP protocol was not designed to perform well over high-latency or noisy channels so its performance over satellite networks are totally different. Each satellite networks/constellations have different properties. The deployment height, motion, direction, link capacity – all differ from one satellite constellations to another. So, certainly the behavior of TCP/IP will considerably differ from one satellite constellations than another.The Performance of three different TCP Congestion algorithms, Vegas, Reno and Bic are taken for evaluation on the simulated satellite network Iridium and the performance of the three algorithms under the satellites constellation is measured using suitable metrics. It is observed that, irrespective of the high end to end delay, the behavior of TCP/IP under Satellite network is somewhat resembling a high latency wired network. TCP under satellite network is not like that of a mobile ADHOC network. The observation resulted that the overall performance of Vegas was good in Iridium constellations. These reasons should be explored for designing a better congestion control algorithm exclusively for Satellite Networks.

  18. Ion mobility sensor system

    Science.gov (United States)

    Xu, Jun; Watson, David B.; Whitten, William B.

    2013-01-22

    An ion mobility sensor system including an ion mobility spectrometer and a differential mobility spectrometer coupled to the ion mobility spectrometer. The ion mobility spectrometer has a first chamber having first end and a second end extending along a first direction, and a first electrode system that generates a constant electric field parallel to the first direction. The differential mobility spectrometer includes a second chamber having a third end and a fourth end configured such that a fluid may flow in a second direction from the third end to the fourth end, and a second electrode system that generates an asymmetric electric field within an interior of the second chamber. Additionally, the ion mobility spectrometer and the differential mobility spectrometer form an interface region. Also, the first end and the third end are positioned facing one another so that the constant electric field enters the third end and overlaps the fluid flowing in the second direction.

  19. Tandem mobile robot system

    Energy Technology Data Exchange (ETDEWEB)

    Buttz, James H. (Albuquerque, NM); Shirey, David L. (Albuquerque, NM); Hayward, David R. (Albuquerque, NM)

    2003-01-01

    A robotic vehicle system for terrain navigation mobility provides a way to climb stairs, cross crevices, and navigate across difficult terrain by coupling two or more mobile robots with a coupling device and controlling the robots cooperatively in tandem.

  20. Mobile systems development

    DEFF Research Database (Denmark)

    Pedersen, Ole; Kristiansen, Martin Lund; Kammersgaard, Marc N.

    2007-01-01

    Development of mobile software is Surrounded by much uncertainty. Immature software platforms on mobile clients, a highly competitive market calling for innovation, efficiency and effectiveness in the development life cycle, and lacking end-user adoption are just some of the realities facing...... development teams in the mobile software industry. By taking a process view on development of mobile systems we seek to explore the strengths and limitations of eXtreme Programming (XP) in the context of mobile software development. Following an experimental approach a mobile systems development project...... running for four months is conducted. Experiences from the project are used for analysis and discussion of the fit of XP in mobile systems development. First, requirements for mobile systems development projects are proposed. Second, these are analysed and compared to the prescribed principles suggested...