WorldWideScience

Sample records for space communication status

  1. Status of High Data Rate Intersatellite Laser Communication as an Enabler for Earth and Space Science

    Heine, F.; Zech, H.; Motzigemba, M.

    2017-12-01

    Space based laser communication is supporting earth observation and science missions with Gbps data download capabilities. Currently the Sentinel 1 and Sentinel 2 spacecrafts from the Copernicus earth observation program of the European Commission are using the Gbps laser communication links developed by Tesat Spacecom to download low latency data products via a commercial geostationary laser relay station- the European Data Relay Service- (EDRS) as a standard data path, in parallel to the conventional radio frequency links. The paper reports on the status of high bandwidth space laser communication as an enabler for small and large space science missions ranging from cube sat applications in low earth orbit to deep space missions. Space based laser communication has left the experimental phase and will support space science missions with unprecedented data rates.

  2. Power Line Communication (PLC) in Space - Current Status and Outlook

    Wolf, J.

    2012-05-01

    The Power Line Communication (PLC) technology as known from various terrestrial applications, e.g. in building automation, in the automotive sector and on aircraft, appears to be a promising technology for the use on spacecraft. Starting from a critical overview on existing terrestrial PLC applications with their pros and cons, the paper gives a motivation for the introduction of the PLC technology on spacecraft, discusses the potential areas where it can be applied and is highlighting the potential problem areas. A short overview of on-going ESA PLC activities is provided and an outlook is given.

  3. Communication spaces.

    Coiera, Enrico

    2014-01-01

    Annotations to physical workspaces such as signs and notes are ubiquitous. When densely annotated, work areas become communication spaces. This study aims to characterize the types and purpose of such annotations. A qualitative observational study was undertaken in two wards and the radiology department of a 440-bed metropolitan teaching hospital. Images were purposefully sampled; 39 were analyzed after excluding inferior images. Annotation functions included signaling identity, location, capability, status, availability, and operation. They encoded data, rules or procedural descriptions. Most aggregated into groups that either created a workflow by referencing each other, supported a common workflow without reference to each other, or were heterogeneous, referring to many workflows. Higher-level assemblies of such groupings were also observed. Annotations make visible the gap between work done and the capability of a space to support work. Annotations are repairs of an environment, improving fitness for purpose, fixing inadequacy in design, or meeting emergent needs. Annotations thus record the missing information needed to undertake tasks, typically added post-implemented. Measuring annotation levels post-implementation could help assess the fit of technology to task. Physical and digital spaces could meet broader user needs by formally supporting user customization, 'programming through annotation'. Augmented reality systems could also directly support annotation, addressing existing information gaps, and enhancing work with context sensitive annotation. Communication spaces offer a model of how work unfolds. Annotations make visible local adaptation that makes technology fit for purpose post-implementation and suggest an important role for annotatable information systems and digital augmentation of the physical environment.

  4. Optical space communication: An overview

    Jain, V.K.

    1994-01-01

    In this paper, importance of the optical space communication has been highlighted. Its merits and demerits over the conventional microwave system has been presented. In contrast to coherent systems, use of an optical preamplifier in direct detection system has been emphasized. Status of some of the ongoing/future space communication projects has been given. (author). 9 refs, 5 figs

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

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

    1986-01-01

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

  6. Free space optical communication

    Kaushal, Hemani; Kar, Subrat

    2017-01-01

    This book provides an in-depth understanding of free space optical (FSO) communication with a particular emphasis on optical beam propagation through atmospheric turbulence. The book is structured in such a way that it provides a basic framework for the beginners and also gives a concise description from a designer’s perspective. The book provides an exposure to FSO technology, fundamental limitations, design methodologies, system trade-offs, acquisition, tracking and pointing (ATP) techniques and link-feasibility analysis. The contents of this book will be of interest to professionals and researchers alike. The book may also be used as a textbook for engineering coursework and professional training.

  7. Silicon Photonics for Space Communications

    National Aeronautics and Space Administration — This proposal is aimed to address level two "Optical Communication and Navigation" needs within the "5.0 Communications, Navigation, and Orbital Debris Tracking and...

  8. Space weather effects on communications

    Lanzerotti, Louis J.

    In the 150 years since the advent of the first electrical communication system - the electrical telegraph - the diversity of communications technologies that are embedded within space-affected environments have vastly increased. The increasing sophistication of these communications technologies, and how their installation and operations may relate to the environments in which they are embedded, requires ever more sophisticated understanding of natural physical phenomena. At the same time, the business environment for most present-day communications technologies that are affected by space phenomena is very dynamic. The commercial and national security deployment and use of these technologies do not wait for optimum knowledge of possible environmental effects to be acquired before new technological embodiments are created, implemented, and marketed. Indeed, those companies that might foolishly seek perfectionist understanding of natural effects can be left behind by the marketplace. A well-considered balance is needed between seeking ever deeper understanding of physical phenomena and implementing `engineering' solutions to current crises. The research community must try to understand, and operate in, this dynamic environment.

  9. The ICA Communication Audit: Process, Status, Critique

    Goldhaber, Gerald M.; Krivonos, Paul D.

    1977-01-01

    Explores the International Communication Association (ICA) Audit process including goals, products, instruments, audit logistics and timetable, feedback of results and follow-up, costs, current status and audits conducted to date. (ED.)

  10. Space industrialization - Education. [via communication satellites

    Joels, K. M.

    1978-01-01

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

  11. Atmospheric free-space coherent optical communications with adaptive optics

    Ting, Chueh; Zhang, Chengyu; Yang, Zikai

    2017-02-01

    Free-space coherent optical communications have a potential application to offer last mile bottleneck solution in future local area networks (LAN) because of their information carrier, information security and license-free status. Coherent optical communication systems using orthogonal frequency division multiplexing (OFDM) digital modulation are successfully demonstrated in a long-haul tens Giga bits via optical fiber, but they are not yet available in free space due to atmospheric turbulence-induced channel fading. Adaptive optics is recognized as a promising technology to mitigate the effects of atmospheric turbulence in free-space optics. In this paper, a free-space coherent optical communication system using an OFDM digital modulation scheme and adaptive optics (FSO OFDM AO) is proposed, a Gamma-Gamma distribution statistical channel fading model for the FSO OFDM AO system is examined, and FSO OFDM AO system performance is evaluated in terms of bit error rate (BER) versus various propagation distances.

  12. Space-bounded communication complexity

    Brody, Joshua Eric; Chen, Shiteng; Papakonstantinou, Periklis A.

    2013-01-01

    communicate his entire input. However, what if the players are limited in their ability to recall parts of their interaction? We introduce memory models for 2-party communication complexity. Our general model is as follows: two computationally unrestricted players, Alice and Bob, each have s(n) bits of memory....... When a player receives a bit of communication, he "compresses" his state. This compression may be an arbitrary function of his current memory contents, his input, and the bit of communication just received; the only restriction is that the compression must return at most s(n) bits. We obtain memory...... controls two types of memory: (i) a large, oblivious memory, where updates are only a function of the received bit and the current memory content, and (ii) a smaller, non-oblivious/general memory, where updates can be a function of the input given to Bob. We exhibit natural protocols where this semi...

  13. The human communication space towards I-centric communications

    Arbanowski, S; Steglich, S; Popescu-Zeletin, R

    2001-01-01

    A variety of concepts for service integration and corresponding systems have been developed. On one hand, they aim for the interworking and integration of classical telecommunications and data communications services. On the other, they are focusing on universal service access from a variety of end-user systems. Many of the technical problems, resulting from service integration and service personalisation, have been solved. However, all these systems are driven by the concept of providing several technologies to users by keeping the peculiarity of each service. Looking at human communication behaviour and communication space, it is obvious that human beings interact habitually in a set of contexts with their environment. The individual information preferences and needs, persons to interact with, and the set of devices controlled by each individual define their personal communication space. Following this view, a new approach is to build communication systems not on the basis of specific technologies, but on t...

  14. Space Shuttle Status News Conference

    2005-01-01

    Richard Gilbech, External Tank "Tiger Team" Lead, begins this space shuttle news conference with detailing the two major objectives of the team. The objectives include: 1) Finding the root cause of the foam loss on STS-114; and 2) Near and long term improvements for the external tank. Wayne Hale, Space Shuttle Program Manager, presents a chart to explain the external tank foam loss during STS-114. He gives a possible launch date for STS-121 after there has been a repair to the foam on the External Tank. He further discusses the changes that need to be made to the surrounding areas of the plant in New Orleans, due to Hurricane Katrina. Bill Gerstemaier, NASA Associate Administrator for Space Operations, elaborates on the testing of the external tank foam loss. The discussion ends with questions from the news media about a fix for the foam, replacement of the tiles, foam loss avoidance, the root cause of foam loss and a possible date for a new external tank to be shipped to NASA Kennedy Space Center.

  15. Transition From NASA Space Communication Systems to Commerical Communication Products

    Ghazvinian, Farzad; Lindsey, William C.

    1994-01-01

    Transitioning from twenty-five years of space communication system architecting, engineering and development to creating and marketing of commercial communication system hardware and software products is no simple task for small, high-tech system engineering companies whose major source of revenue has been the U.S. Government. Yet, many small businesses are faced with this onerous and perplexing task. The purpose of this talk/paper is to present one small business (LinCom) approach to taking advantage of the systems engineering expertise and knowledge captured in physical neural networks and simulation software by supporting numerous National Aeronautics and Space Administration (NASA) and the Department of Defense (DoD) projects, e.g., Space Shuttle, TDRSS, Space Station, DCSC, Milstar, etc. The innovative ingredients needed for a systems house to transition to a wireless communication system products house that supports personal communication services and networks (PCS and PCN) development in a global economy will be discussed. Efficient methods for using past government sponsored space system research and development to transition to VLSI communication chip set products will be presented along with notions of how synergy between government and industry can be maintained to benefit both parties.

  16. Space Launch System Development Status

    Lyles, Garry

    2014-01-01

    Development of NASA's Space Launch System (SLS) heavy lift rocket is shifting from the formulation phase into the implementation phase in 2014, a little more than three years after formal program approval. Current development is focused on delivering a vehicle capable of launching 70 metric tons (t) into low Earth orbit. This "Block 1" configuration will launch the Orion Multi-Purpose Crew Vehicle (MPCV) on its first autonomous flight beyond the Moon and back in December 2017, followed by its first crewed flight in 2021. SLS can evolve to a130-t lift capability and serve as a baseline for numerous robotic and human missions ranging from a Mars sample return to delivering the first astronauts to explore another planet. Benefits associated with its unprecedented mass and volume include reduced trip times and simplified payload design. Every SLS element achieved significant, tangible progress over the past year. Among the Program's many accomplishments are: manufacture of Core Stage test panels; testing of Solid Rocket Booster development hardware including thrust vector controls and avionics; planning for testing the RS-25 Core Stage engine; and more than 4,000 wind tunnel runs to refine vehicle configuration, trajectory, and guidance. The Program shipped its first flight hardware - the Multi-Purpose Crew Vehicle Stage Adapter (MSA) - to the United Launch Alliance for integration with the Delta IV heavy rocket that will launch an Orion test article in 2014 from NASA's Kennedy Space Center. Objectives of this Earth-orbit flight include validating the performance of Orion's heat shield and the MSA design, which will be manufactured again for SLS missions to deep space. The Program successfully completed Preliminary Design Review in 2013 and Key Decision Point C in early 2014. NASA has authorized the Program to move forward to Critical Design Review, scheduled for 2015 and a December 2017 first launch. The Program's success to date is due to prudent use of proven

  17. Free Space Optical Communication for Tactical Operations

    2016-09-01

    higher energy level to a lower energy level. The photons are focused to optical lenses before transmission into the air medium. The primary purpose...Security of a free space optical transmission . (n.d.). SONA Optical Wireless , [Online]. Available: http://htcbn.com/HTC_Profile_CD/fSONA/APPNOTE...almost always require on-the-move wireless communications. Radio frequency (RF) communication is used to fill the gap, but RF systems are hard pressed to

  18. Monolithic microwave integrated circuit technology for advanced space communication

    Ponchak, George E.; Romanofsky, Robert R.

    1988-01-01

    Future Space Communications subsystems will utilize GaAs Monolithic Microwave Integrated Circuits (MMIC's) to reduce volume, weight, and cost and to enhance system reliability. Recent advances in GaAs MMIC technology have led to high-performance devices which show promise for insertion into these next generation systems. The status and development of a number of these devices operating from Ku through Ka band will be discussed along with anticipated potential applications.

  19. Religion and Communication Spaces. A Semio-pragmatic Approach

    Roger Odin

    2015-11-01

    Full Text Available Following the reflection initiated in his book The Spaces of Communication, Roger Odin suggests a new distinction between physical communication spaces and mental communication spaces (spaces that we have inside us. The suggestion is exemplified by three film analyses dedicated to the relationships between religion and communication.

  20. Infrared Free Space Communication - The Autonomous Testing of Free Space Infrared Communication

    Heldman, Christopher

    2017-01-01

    Fiber optics has been a winning player in the game of high-speed communication and data transfer in cable connections. Yet, in free space RF has been the repeated choice of communication medium of the space industry. Investigating the benefits of free space optical communication over radio frequency is worthwhile. An increase in science data rate return capabilities could occur if optical communication is implemented. Optical communication systems also provide efficiencies in power, mass, and volume over RF systems1. Optical communication systems have been demonstrated from a satellite in orbit with the moon to earth, and resulted in the highest data rates ever seen through space (622Mbps)2. Because of these benefits, optical communication is far superior to RF. The HiDRA (High Data Rate Architecture) project is researching Passive Misalignment Mitigation of Dynamic Free Apace Optical Communication Links. The goal of this effort is to enable gigabit per second transmission of data in short range dynamic links (less than 100 meters). In practice this would enhance data rates between sites on the International Space Station with minimal size, weight, and power requirements. This paper will focus on an autonomous code and a hardware setup that will be used to fulfill the next step in the research being conducted. The free space optical communications pointing downfalls will be investigated. This was achieved by creating 5 python programs and a top-level code to automate this test.

  1. NASA's current activities in free space optical communications

    Edwards, Bernard L.

    2017-11-01

    NASA and other space agencies around the world are currently developing free space optical communication systems for both space-to-ground links and space-to-space links. This paper provides an overview of NASA's current activities in free space optical communications with a focus on Near Earth applications. Activities to be discussed include the Lunar Laser Communication Demonstration, the Laser Communications Relay Demonstration, and the commercialization of the underlying technology. The paper will also briefly discuss ongoing efforts and studies for Deep Space optical communications. Finally the paper will discuss the development of international optical communication standards within the Consultative Committee for Space Data Systems.

  2. Space Shuttle Underside Astronaut Communications Performance Evaluation

    Hwu, Shian U.; Dobbins, Justin A.; Loh, Yin-Chung; Kroll, Quin D.; Sham, Catherine C.

    2005-01-01

    The Space Shuttle Ultra High Frequency (UHF) communications system is planned to provide Radio Frequency (RF) coverage for astronauts working underside of the Space Shuttle Orbiter (SSO) for thermal tile inspection and repairing. This study is to assess the Space Shuttle UHF communication performance for astronauts in the shadow region without line-of-sight (LOS) to the Space Shuttle and Space Station UHF antennas. To insure the RF coverage performance at anticipated astronaut worksites, the link margin between the UHF antennas and Extravehicular Activity (EVA) Astronauts with significant vehicle structure blockage was analyzed. A series of near-field measurements were performed using the NASA/JSC Anechoic Chamber Antenna test facilities. Computational investigations were also performed using the electromagnetic modeling techniques. The computer simulation tool based on the Geometrical Theory of Diffraction (GTD) was used to compute the signal strengths. The signal strength was obtained by computing the reflected and diffracted fields along the propagation paths between the transmitting and receiving antennas. Based on the results obtained in this study, RF coverage for UHF communication links was determined for the anticipated astronaut worksite in the shadow region underneath the Space Shuttle.

  3. Downlink Fiber Laser Transmitter for Deep Space Communication, Phase II

    National Aeronautics and Space Administration — NASA's Space Communications and Navigation (SCaN) roadmap, calls for an integrated network approach to communication and navigation needs for robotic and human space...

  4. Asynchronous communication in real space process algebra

    Baeten, J.C.M.; Bergstra, J.A.

    1991-01-01

    A version of classical real space process algebra is given in which messages travel with constant speed through a three-dimensional medium. It follows that communication is asynchronous and has a broadcasting character. A state operator is used to describe asynchronous message transfer and a

  5. Asynchronous communication in real space process algebra

    Bergstra, J.A.; Baeten, J.C.M.

    1992-01-01

    A version of classical real space process algebra is given in which messages travel with constant speed through a three-dimensional medium. It follows that communication is asynchronous and has a broadcasting character. A state operator is used to describe asynchronous message transfer and a

  6. National Aeronautics and Space Administration plans for space communication technology

    Alexovich, R. E.

    1979-01-01

    A program plan is presented for a space communications application utilizing the 30/20 GHz frequency bands (30 GHz uplink and 20 GHz downlink). Results of market demand studies and spacecraft systems studies which significantly affect the supporting research and technology program are also presented, along with the scheduled activities of the program plan.

  7. Status of SPACE Safety Analysis Code Development

    Lee, Dong Hyuk; Yang, Chang Keun; Kim, Se Yun; Ha, Sang Jun

    2009-01-01

    In 2006, the Korean the Korean nuclear industry started developing a thermal-hydraulic analysis code for safety analysis of PWR(Pressurized Water Reactor). The new code is named as SPACE(Safety and Performance Analysis Code for Nuclear Power Plant). The SPACE code can solve two-fluid, three-field governing equations in one dimensional or three dimensional geometry. The SPACE code has many component models required for modeling a PWR, such as reactor coolant pump, safety injection tank, etc. The programming language used in the new code is C++, for new generation of engineers who are more comfortable with C/C++ than old FORTRAN language. This paper describes general characteristics of SPACE code and current status of SPACE code development

  8. Challenges of Integrating NASA's Space Communications Networks

    Reinert, Jessica; Barnes, Patrick

    2013-01-01

    The transition to new technology, innovative ideas, and resistance to change is something that every industry experiences. Recent examples of this shift are changing to using robots in the assembly line construction of automobiles or the increasing use of robotics for medical procedures. Most often this is done with cost-reduction in mind, though ease of use for the customer is also a driver. All industries experience the push to increase efficiency of their systems; National Aeronautics and Space Administration (NASA) and the commercial space industry are no different. NASA space communication services are provided by three separately designed, developed, maintained, and operated communications networks known as the Deep Space Network (DSN), Near Earth Network (NEN) and Space Network (SN). The Space Communications and Navigation (SCaN) Program is pursuing integration of these networks and has performed a variety of architecture trade studies to determine what integration options would be the most effective in achieving a unified user mission support organization, and increase the use of common operational equipment and processes. The integration of multiple, legacy organizations and existing systems has challenges ranging from technical to cultural. The existing networks are the progeny of the very first communication and tracking capabilities implemented by NASA and the Jet Propulsion Laboratory (JPL) more than 50 years ago and have been customized to the needs of their respective user mission base. The technical challenges to integrating the networks are many, though not impossible to overcome. The three distinct networks provide the same types of services, with customizable data rates, bandwidth, frequencies, and so forth. The differences across the networks have occurred in effort to satisfy their user missions' needs. Each new requirement has made the networks more unique and harder to integrate. The cultural challenges, however, have proven to be a

  9. Challenges of Integrating NASAs Space Communication Networks

    Reinert, Jessica M.; Barnes, Patrick

    2013-01-01

    The transition to new technology, innovative ideas, and resistance to change is something that every industry experiences. Recent examples of this shift are changing to using robots in the assembly line construction of automobiles or the increasing use of robotics for medical procedures. Most often this is done with cost-reduction in mind, though ease of use for the customer is also a driver. All industries experience the push to increase efficiency of their systems; National Aeronautics and Space Administration (NASA) and the commercial space industry are no different. NASA space communication services are provided by three separately designed, developed, maintained, and operated communications networks known as the Deep Space Network (DSN), Near Earth Network (NEN) and Space Network (SN). The Space Communications and Navigation (SCaN) Program is pursuing integration of these networks and has performed a variety of architecture trade studies to determine what integration options would be the most effective in achieving a unified user mission support organization, and increase the use of common operational equipment and processes. The integration of multiple, legacy organizations and existing systems has challenges ranging from technical to cultural. The existing networks are the progeny of the very first communication and tracking capabilities implemented by NASA and the Jet Propulsion Laboratory (JPL) more than 50 years ago and have been customized to the needs of their respective user mission base. The technical challenges to integrating the networks are many, though not impossible to overcome. The three distinct networks provide the same types of services, with customizable data rates, bandwidth, frequencies, and so forth. The differences across the networks have occurred in effort to satisfy their user missions' needs. Each new requirement has made the networks more unique and harder to integrate. The cultural challenges, however, have proven to be a

  10. Diamond Electron-Spin Clocks For Space Navigation and Communication

    National Aeronautics and Space Administration — Precision clocks are needed in a broad range of applications, including satellite communication, high-bandwidth wireless communication, computing systems, and...

  11. Present status of space nuclear reactor

    Kaneko, Yoshihiko

    1996-01-01

    USA and former USSR led space development, and had the experience of launching nuclear reactor satellites. In USA, the research and development of space nuclear reactor were advanced mainly by NASA, and in 1965, the nuclear reactor for power source ''SNAP-10A'' was launched and put on the orbit around the earth. Thereafter, the reactor was started up, and the verifying test at 500 We was successfully carried out. Also for developing the reactor for thermal propulsion, NERVA/ROVER project was done till 1973, and the technological basis was established. The space Exploration Initiative for sending mankind to other solar system planets than the earth is the essential point of the future projects. In former USSR, the ground experiment of the reactor for 800 We power source ''Romashka'', the development of the reactor for 10 kWe power source ''Topaz-1 and 2'', the flight of the artificial satellites, Cosmos 954 and Cosmos 1900, on which nuclear reactors were mounted, and the operation of 33 ocean-monitoring satellites ''RORSAT'' using small fast reactors were carried out. The mission of space development and the nuclear reactors as power source, the engineering of space nuclear reactors, the present status and the trend of space nuclear reactor development, and the investigation by the UN working group on the safety problem of space nuclear reactors are described. (K.I.)

  12. Deep space optical communication via relay satellite

    Dolinar, S.; Vilnrotter, V.; Gagliardi, R.

    1981-01-01

    The application of optical communications for a deep space link via an earth-orbiting relay satellite is discussed. The system uses optical frequencies for the free-space channel and RF links for atmospheric transmission. The relay satellite is in geostationary orbit and contains the optics necessary for data processing and formatting. It returns the data to earth through the RF terrestrial link and also transmits an optical beacon to the satellite for spacecraft return pointing and for the alignment of the transmitting optics. Future work will turn to modulation and coding, pointing and tracking, and optical-RF interfacing.

  13. Digital communication constraints in prior space missions

    Yassine, Nathan K.

    2004-01-01

    Digital communication is crucial for space endeavors. Jt transmits scientific and command data between earth stations and the spacecraft crew. It facilitates communications between astronauts, and provides live coverage during all phases of the mission. Digital communications provide ground stations and spacecraft crew precise data on the spacecraft position throughout the entire mission. Lessons learned from prior space missions are valuable for our new lunar and Mars missions set by our president s speech. These data will save our agency time and money, and set course our current developing technologies. Limitations on digital communications equipment pertaining mass, volume, data rate, frequency, antenna type and size, modulation, format, and power in the passed space missions are of particular interest. This activity is in support of ongoing communication architectural studies pertaining to robotic and human lunar exploration. The design capabilities and functionalities will depend on the space and power allocated for digital communication equipment. My contribution will be gathering these data, write a report, and present it to Communications Technology Division Staff. Antenna design is very carefully studied for each mission scenario. Currently, Phased array antennas are being developed for the lunar mission. Phased array antennas use little power, and electronically steer a beam instead of DC motors. There are 615 patches in the phased array antenna. These patches have to be modified to have high yield. 50 patches were created for testing. My part is to assist in the characterization of these patch antennas, and determine whether or not certain modifications to quartz micro-strip patch radiators result in a significant yield to warrant proceeding with repairs to the prototype 19 GHz ferroelectric reflect-array antenna. This work requires learning how to calibrate an automatic network, and mounting and testing antennas in coaxial fixtures. The purpose of this

  14. Asynchronous communication in real space process algebra

    Baeten, JCM Jos; Bergstra, JA Jan

    1990-01-01

    A version of classical real space process algebra is given in which messages travel with constant speed through a three-dimensional medium. It follows that communication is asynchronous and has a broadcasting character. A state operator is used to describe asynchronous message transfer and a priority mechanism allows to express the broadcasting mechanism. As an application, a protocol is specified in which the receiver moves with respect to the sender.

  15. Free-space communication with over 100 spatial modes

    Rosales-Guzmán, C

    2016-10-01

    Full Text Available Congress 2016: Advanced Solid State Lasers (ASSL); Applications of Lasers for Sensing and Free Space Communications (LS&C), 30 October - 3 November 2016, Boston, Massachusetts, United States Free-space communication with over 100 spatial modes...

  16. Implementation of a Space Communications Cognitive Engine

    Hackett, Timothy M.; Bilen, Sven G.; Ferreira, Paulo Victor R.; Wyglinski, Alexander M.; Reinhart, Richard C.

    2017-01-01

    Although communications-based cognitive engines have been proposed, very few have been implemented in a full system, especially in a space communications system. In this paper, we detail the implementation of a multi-objective reinforcement-learning algorithm and deep artificial neural networks for the use as a radio-resource-allocation controller. The modular software architecture presented encourages re-use and easy modification for trying different algorithms. Various trade studies involved with the system implementation and integration are discussed. These include the choice of software libraries that provide platform flexibility and promote reusability, choices regarding the deployment of this cognitive engine within a system architecture using the DVB-S2 standard and commercial hardware, and constraints placed on the cognitive engine caused by real-world radio constraints. The implemented radio-resource allocation-management controller was then integrated with the larger spaceground system developed by NASA Glenn Research Center (GRC).

  17. Fiber Optic Communications Technology. A Status Report.

    Hull, Joseph A.

    Fiber optic communications (communications over very pure glass transmission channels of diameter comparable to a human hair) is an emerging technology which promises most improvements in communications capacity at reasonable cost. The fiber transmission system offers many desirable characteristics representing improvements over conventional…

  18. 47 CFR 25.273 - Duties regarding space communications transmissions.

    2010-10-01

    ... 47 Telecommunication 2 2010-10-01 2010-10-01 false Duties regarding space communications transmissions. 25.273 Section 25.273 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) COMMON CARRIER SERVICES SATELLITE COMMUNICATIONS Technical Operations § 25.273 Duties regarding space...

  19. Research in space commercialization, technology transfer and communications, vol. 2

    Dunn, D. A.; Agnew, C. E.

    1983-01-01

    Spectrum management, models for evaluating communications systems, and implications of communications regulations for NASA are considered as major parts of communications policy. Marketing LANDSAT products in developing countries, a political systems analysis of LANDSAT, and private financing and operation of the space operations center (space station) are discussed. Investment requirements, risks, government support, and other primary business and management considerations are examined.

  20. Discovery deep space optical communications (DSOC) transceiver

    Roberts, W. Thomas

    2017-02-01

    NASA's 22 cm diameter Deep Space Optical Communications (DSOC) Transceiver is designed to provide a bidirectional optical link between a spacecraft in the inner solar system and an Earth-based optical ground station. This design, optimized for operation across a wide range of illumination conditions, is focused on minimizing blinding from stray light, and providing reliable, accurate attitude information to point its narrow communication beam accurately to the future location of the ground terminal. Though our transceiver will transmit in the 1550 nm waveband and receive in the 1064 nm waveband, the system design relies heavily on reflective optical elements, extending flexibility to be modified for use at different wavebands. The design makes use of common path propagation among transmit, receive and pointing verification optical channels to maintain precise alignment among its components, and to naturally correct for element misalignment resulting from launch or thermal element perturbations. This paper presents the results of trade studies showing the evolution of the design, unique operational characteristics of the design, elements that help to maintain minimal stray light contamination, and preliminary results from development and initial testing of a functional aluminum test model.

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

    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.

  2. High Power Uplink Amplifier for Deep Space Communications, Phase II

    National Aeronautics and Space Administration — Critical to the success of delivering on the promise of deep space optical communications is the creation of a stable and reliable high power multichannel optical...

  3. High Power Uplink Amplifier for Deep Space Communications, Phase I

    National Aeronautics and Space Administration — Critical to the success of delivering on the promise of deep space optical communications is the creation of a stable and reliable high power multichannel optical...

  4. Space life sciences: A status report

    1990-01-01

    The scientific research and supporting technology development conducted in the Space Life Sciences Program is described. Accomplishments of the past year are highlighted. Plans for future activities are outlined. Some specific areas of study include the following: Crew health and safety; What happens to humans in space; Gravity, life, and space; Sustenance in space; Life and planet Earth; Life in the Universe; Promoting good science and good will; Building a future for the space life sciences; and Benefits of space life sciences research.

  5. Securing Data for Space Communications, Phase I

    National Aeronautics and Space Administration — NASA's vision of data exchange between space and ground nodes would involve the space network accessing public infrastructure such as the internet. Hence, advanced...

  6. Communicating space weather to policymakers and the wider public

    Ferreira, Bárbara

    2014-05-01

    As a natural hazard, space weather has the potential to affect space- and ground-based technological systems and cause harm to human health. As such, it is important to properly communicate this topic to policymakers and the general public alike, informing them (without being unnecessarily alarmist) about the potential impact of space-weather phenomena and how these can be monitored and mitigated. On the other hand, space weather is related to interesting phenomena on the Sun such as coronal-mass ejections, and incorporates one of the most beautiful displays in the Earth and its nearby space environment: aurora. These exciting and fascinating aspects of space weather should be cultivated when communicating this topic to the wider public, particularly to younger audiences. Researchers have a key role to play in communicating space weather to both policymakers and the wider public. Space scientists should have an active role in informing policy decisions on space-weather monitoring and forecasting, for example. And they can exercise their communication skills by talking about space weather to school children and the public in general. This presentation will focus on ways to communicate space weather to wider audiences, particularly policymakers. It will also address the role researchers can play in this activity to help bridge the gap between the space science community and the public.

  7. Japan's telecommunications - New initiatives in space communications

    Iida, T.

    1992-04-01

    Despite recent advances in optical transmission technology, intensive R&D work in the field of satellite communications is now being undertaken in Japan. It is believed that satellites offer advantages in several important areas, including wide coverage broadcasting, immediacy of service, suitability for the implementation of HDTV, and advantages in disaster communications and other social services. Here, some experimental projects in the field of satellite communications planned in Japan for the 1990s are summarized. In particular, attention is given to broadcast satellite development, intersatellite links, advanced mobile communication concepts, large antenna assembly experiment, small satellite R&D, and Pan-Pacific information network experiment.

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

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

    1999-01-01

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

  9. User Needs and Advances in Space Wireless Sensing and Communications

    Kegege, Obadiah

    2017-01-01

    Decades of space exploration and technology trends for future missions show the need for new approaches in space/planetary sensor networks, observatories, internetworking, and communications/data delivery to Earth. The User Needs to be discussed in this talk includes interviews with several scientists and reviews of mission concepts for the next generation of sensors, observatories, and planetary surface missions. These observatories, sensors are envisioned to operate in extreme environments, with advanced autonomy, whereby sometimes communication to Earth is intermittent and delayed. These sensor nodes require software defined networking capabilities in order to learn and adapt to the environment, collect science data, internetwork, and communicate. Also, some user cases require the level of intelligence to manage network functions (either as a host), mobility, security, and interface data to the physical radio/optical layer. For instance, on a planetary surface, autonomous sensor nodes would create their own ad-hoc network, with some nodes handling communication capabilities between the wireless sensor networks and orbiting relay satellites. A section of this talk will cover the advances in space communication and internetworking to support future space missions. NASA's Space Communications and Navigation (SCaN) program continues to evolve with the development of optical communication, a new vision of the integrated network architecture with more capabilities, and the adoption of CCSDS space internetworking protocols. Advances in wireless communications hardware and electronics have enabled software defined networking (DVB-S2, VCM, ACM, DTN, Ad hoc, etc.) protocols for improved wireless communication and network management. Developing technologies to fulfil these user needs for wireless communications and adoption of standardized communication/internetworking protocols will be a huge benefit to future planetary missions, space observatories, and manned missions

  10. Exploring the architectural trade space of NASAs Space Communication and Navigation Program

    Sanchez, M.; Selva, D.; Cameron, B.; Crawley, E.; Seas, A.; Seery, B.

    NASAs Space Communication and Navigation (SCaN) Program is responsible for providing communication and navigation services to space missions and other users in and beyond low Earth orbit. The current SCaN architecture consists of three independent networks: the Space Network (SN), which contains the TDRS relay satellites in GEO; the Near Earth Network (NEN), which consists of several NASA owned and commercially operated ground stations; and the Deep Space Network (DSN), with three ground stations in Goldstone, Madrid, and Canberra. The first task of this study is the stakeholder analysis. The goal of the stakeholder analysis is to identify the main stakeholders of the SCaN system and their needs. Twenty-one main groups of stakeholders have been identified and put on a stakeholder map. Their needs are currently being elicited by means of interviews and an extensive literature review. The data will then be analyzed by applying Cameron and Crawley's stakeholder analysis theory, with a view to highlighting dominant needs and conflicting needs. The second task of this study is the architectural tradespace exploration of the next generation TDRSS. The space of possible architectures for SCaN is represented by a set of architectural decisions, each of which has a discrete set of options. A computational tool is used to automatically synthesize a very large number of possible architectures by enumerating different combinations of decisions and options. The same tool contains models to evaluate the architectures in terms of performance and cost. The performance model uses the stakeholder needs and requirements identified in the previous steps as inputs, and it is based in the VASSAR methodology presented in a companion paper. This paper summarizes the current status of the MIT SCaN architecture study. It starts by motivating the need to perform tradespace exploration studies in the context of relay data systems through a description of the history NASA's space communicati

  11. Facility for the evaluation of space communications and related systems

    Kerczewski, Robert J.; Svoboda, James S.; Kachmar, Brian A.

    1995-01-01

    NASA Lewis Research Center's Communications Projects Branch has developed a facility for the evaluation of space communications systems and related types of systems, called the Advanced Space Communications (ASC) Laboratory. The ASC Lab includes instrumentation, testbed hardware, and experiment control and monitor software for the evaluation of components, subsystems, systems, and networks. The ASC lab has capabilities to perform radiofrequency (RF), microwave, and millimeter-wave characterizations as well as measurements using low, medium, or high data rate digital signals. In addition to laboratory measurements, the ASC Lab also includes integrated satellite ground terminals allowing experimentation and measurements accessing operational satellites through real space links.

  12. Spectrum Scarcity and Free Space Optical Communications

    Alouini, Mohamed-Slim

    2014-01-01

    Exact and asymptotic studies of the average error probability of wireless communication systems over generalized fading channels have been extensively pursued over the last two decades. In contrast, studies and results dealing with the channel

  13. The museum foyer as a transformative space of communication

    Laursen, Ditte; Kristiansen, Erik; Drotner, Kirsten

    2016-01-01

    has four transformative functions, and we ask the following question: How do people entering the museum practise these transformative functions so as to become visitors – and become non-visitors again on leaving? Answers are provided through an empirical analysis of the foyer as a transformative...... communicative space. Based on qualitative studies of four divergent Danish museums and a science centre, we demonstrate that the foyer’s communicative space supports transformative functions consisting of multiple phases before and after the visit itself, namely arrival–orientation–service–preparation (before......This article explores how we may study physical museum foyers as multilayered spaces of communication. Based on a critical examination of ways in which the museum foyer is conceptualised in the research literature, we define the foyer as a transformative space of communication for visitors which...

  14. Precoded generalized space shift keying for indoor visible light communications

    Kadampot, Ishaque Ashar; Park, Kihong; Alouini, Mohamed-Slim

    2014-01-01

    We consider a visible light communication system with 2 transmit light emitting diodes (LED) and nr receive photodiodes. An optical generalized space shift keying modulation scheme is considered for the transmission of bits where each LED can

  15. Exotic Optical Beam Classes for Free-Space Communication

    2016-03-24

    wandering of an optical vortex is one of the significant problems with the application of vortex beams to FSO applications. From a geometrical optics ...AFRL-AFOSR-VA-TR-2016-0131 Exotic optical beam classes for free-space communication Greg Gbur UNIVERSITY OF NOTH CAROLINA AT CHARLOTTE Final Report...12-2015 4. TITLE AND SUBTITLE Exotic optical beam classes for free-space communication 5a. CONTRACT NUMBER 5b. GRANT NUMBER FA9550-13-1-0009 5c

  16. Diaspora: Multilingual and Intercultural Communication across Time and Space

    Wei, Li; Hua, Zhu

    2013-01-01

    The nature of diaspora is changing in the 21st century. Yet many of the communication issues remain the same. At the heart of it is multilingual and intercultural communication across time and space. There is much that applied linguists can contribute to the understanding of diaspora in the era of globalization. This article discusses some of the…

  17. Space Communications Capability Roadmap Interim Review

    Spearing, Robert; Regan, Michael

    2005-01-01

    Contents include the following: Identify the need for a robust communications and navigation architecture for the success of exploration and science missions. Describe an approach for specifying architecture alternatives and analyzing them. Establish a top level architecture based on a network of networks. Identify key enabling technologies. Synthesize capability, architecture and technology into an initial capability roadmap.

  18. Diffractive optical elements for space communication terminals

    Herzig, Hans-Peter; Ehbets, Peter; Teijido, Juan M.; Weible, Kenneth J.; Heimbeck, Hans-Joerg

    2007-01-01

    The potential of diffractive optical elements for advanced laser communication terminals has been investigated. Applications include beam shaping of high- power laser diode arrays, optical filter elements for position detection and hybrid (refractive/diffractive) elements. In addition, we present a design example of a miniaturized terminal including diffractive optics.

  19. Space communication and radar with lasers

    Witteman, W.J.

    2005-01-01

    Sensitive heterodyne detection with lasers applied .to radar and satellite communication is seriously hampered by the large electronic bandwidth due to random Doppler shift and frequency instability. These drawbacks can be circumvented by dual signal heterodyne detection. The system consists of

  20. MMIC technology for advanced space communications systems

    Downey, A. N.; Connolly, D. J.; Anzic, G.

    The current NASA program for 20 and 30 GHz monolithic microwave integrated circuit (MMIC) technology is reviewed. The advantages of MMIC are discussed. Millimeter wavelength MMIC applications and technology for communications systems are discussed. Passive and active MMIC compatible components for millimeter wavelength applications are investigated. The cost of a millimeter wavelength MMIC's is projected.

  1. MMIC technology for advanced space communications systems

    Downey, A. N.; Connolly, D. J.; Anzic, G.

    1984-01-01

    The current NASA program for 20 and 30 GHz monolithic microwave integrated circuit (MMIC) technology is reviewed. The advantages of MMIC are discussed. Millimeter wavelength MMIC applications and technology for communications systems are discussed. Passive and active MMIC compatible components for millimeter wavelength applications are investigated. The cost of a millimeter wavelength MMIC's is projected.

  2. Space Shuttle Communications Coverage Analysis for Thermal Tile Inspection

    Kroll, Quin D.; Hwu, Shian U.; Upanavage, Matthew; Boster, John P.; Chavez, Mark A.

    2009-01-01

    The space shuttle ultra-high frequency Space-to-Space Communication System has to provide adequate communication coverage for astronauts who are performing thermal tile inspection and repair on the underside of the space shuttle orbiter (SSO). Careful planning and quantitative assessment are necessary to ensure successful system operations and mission safety in this work environment. This study assesses communication systems performance for astronauts who are working in the underside, non-line-of-sight shadow region on the space shuttle. All of the space shuttle and International Space Station (ISS) transmitting antennas are blocked by the SSO structure. To ensure communication coverage at planned inspection worksites, the signal strength and link margin between the SSO/ISS antennas and the extravehicular activity astronauts, whose line-of-sight is blocked by vehicle structure, was analyzed. Investigations were performed using rigorous computational electromagnetic modeling techniques. Signal strength was obtained by computing the reflected and diffracted fields along the signal propagation paths between transmitting and receiving antennas. Radio frequency (RF) coverage was determined for thermal tile inspection and repair missions using the results of this computation. Analysis results from this paper are important in formulating the limits on reliable communication range and RF coverage at planned underside inspection and repair worksites.

  3. Systems and methods for free space optical communication

    Harper, Warren W [Benton City, WA; Aker, Pamela M [Richland, WA; Pratt, Richard M [Richland, WA

    2011-05-10

    Free space optical communication methods and systems, according to various aspects are described. The methods and systems are characterized by transmission of data through free space with a digitized optical signal acquired using wavelength modulation, and by discrimination between bit states in the digitized optical signal using a spectroscopic absorption feature of a chemical substance.

  4. Status Report of Simulated Space Radiation Environment Facility

    Kang, Phil Hyun; Nho, Young Chang; Jeun, Joon Pyo; Choi, Jae Hak; Lim, Youn Mook; Jung, Chan Hee; Jeon, Young Kyu

    2007-11-15

    The technology for performance testing and improvement of materials which are durable at space environment is a military related technology and veiled and securely regulated in advanced countries such as US and Russia. This core technology cannot be easily transferred to other country too. Therefore, this technology is the most fundamental and necessary research area for the successful establishment of space environment system. Since the task for evaluating the effects of space materials and components by space radiation plays important role in satellite lifetime extension and running failure percentage decrease, it is necessary to establish simulated space radiation facility and systematic testing procedure. This report has dealt with the status of the technology to enable the simulation of space environment effects, including the effect of space radiation on space materials. This information such as the fundamental knowledge of space environment and research status of various countries as to the simulation of space environment effects of space materials will be useful for the research on radiation hardiness of the materials. Furthermore, it will be helpful for developer of space material on deriving a better choice of materials, reducing the design cycle time, and improving safety.

  5. Status Report of Simulated Space Radiation Environment Facility

    Kang, Phil Hyun; Nho, Young Chang; Jeun, Joon Pyo; Choi, Jae Hak; Lim, Youn Mook; Jung, Chan Hee; Jeon, Young Kyu

    2007-11-01

    The technology for performance testing and improvement of materials which are durable at space environment is a military related technology and veiled and securely regulated in advanced countries such as US and Russia. This core technology cannot be easily transferred to other country too. Therefore, this technology is the most fundamental and necessary research area for the successful establishment of space environment system. Since the task for evaluating the effects of space materials and components by space radiation plays important role in satellite lifetime extension and running failure percentage decrease, it is necessary to establish simulated space radiation facility and systematic testing procedure. This report has dealt with the status of the technology to enable the simulation of space environment effects, including the effect of space radiation on space materials. This information such as the fundamental knowledge of space environment and research status of various countries as to the simulation of space environment effects of space materials will be useful for the research on radiation hardiness of the materials. Furthermore, it will be helpful for developer of space material on deriving a better choice of materials, reducing the design cycle time, and improving safety

  6. Unified Communications for Space Inventory Management

    Gifford, Kevin K.; Fink, Patrick W.; Barton, Richard; Ngo, Phong H.

    2009-01-01

    To help assure mission success for long-duration exploration activities, NASA is actively pursuing wireless technologies that promote situational awareness and autonomy. Wireless technologies are typically extensible, offer freedom from wire tethers, readily support redundancy, offer potential for decreased wire weight, and can represent dissimilar implementation for increased reliability. In addition, wireless technologies can enable additional situational awareness that otherwise would be infeasible. For example, addition of wired sensors, the need for which might not have been apparent at the outset of a program, night be extremely costly due in part to the necessary routing of cables through the vehicle. RFID, or radio frequency identification, is a wireless technology with the potential for significant savings and increased reliability and safety in space operations. Perhaps the most obvious savings relate to the application of inventory management. A fully automated inventory management system is highly desirable for long-term sustaining operations in space environments. This assertion is evidenced by inventory activities on the International Space Station, which represents the most extensive inventory tracking experience base in the history of space operations. In the short tern, handheld RFID readers offer substantial savings owing to reduced crew time for inventory audits. Over the long term, a combination of improved RFID technology and operational concepts modified to fully utilize the technology should result in space based inventory management that is highly reliable and requires very little crew time. In addition to inventory management, RFID is likely to find space applications in real-time location and tracking systems. These could vary from coarse-resolution RFID portals to the high resolution afforded by ultra-wideband (UWB) RFID. Longer range RFID technologies that leverage passive surface acoustic wave (SAW) devices are being investigated to

  7. Beaconless Pointing for Deep-Space Optical Communication

    Swank, Aaron J.; Aretskin-Hariton, Eliot; Le, Dzu K.; Sands, Obed S.; Wroblewski, Adam

    2016-01-01

    Free space optical communication is of interest to NASA as a complement to existing radio frequency communication methods. The potential for an increase in science data return capability over current radio-frequency communications is the primary objective. Deep space optical communication requires laser beam pointing accuracy on the order of a few microradians. The laser beam pointing approach discussed here operates without the aid of a terrestrial uplink beacon. Precision pointing is obtained from an on-board star tracker in combination with inertial rate sensors and an outgoing beam reference vector. The beaconless optical pointing system presented in this work is the current approach for the Integrated Radio and Optical Communication (iROC) project.

  8. Architectural Options for a Future Deep Space Optical Communications Network

    Edwards, B. L.; Benjamin, T.; Scozzafava, J.; Khatri, F.; Sharma, J.; Parvin, B.; Liebrecht, P. E.; Fitzgerald, R. J.

    2004-01-01

    This paper provides an overview of different options at Earth to provide Deep Space optical communication services. It is based mainly on work done for the Mars Laser Communications Demonstration (MLCD) Project, a joint project between NASA's Goddard Space Flight Center (GSFC), the Jet Propulsion Laboratory, California Institute of Technology (JPL), and the Massachusetts Institute of Technology Lincoln Laboratory (MIT/LL). It also reports preliminary conclusions from the Tracking and Data Relay Satellite System Continuation Study at GSFC. A lasercom flight terminal will be flown on the Mars Telecommunications Orbiter (MTO) to be launched by NASA in 2009, and will be the first high rate deep space demonstration of this revolutionary technology.

  9. NASA's Space Launch System Development Status

    Lyles, Garry

    2014-01-01

    Development of the National Aeronautics and Space Administration's (NASA's) Space Launch System (SLS) heavy lift rocket is shifting from the formulation phase into the implementation phase in 2014, a little more than 3 years after formal program establishment. Current development is focused on delivering a vehicle capable of launching 70 metric tons (t) into low Earth orbit. This "Block 1" configuration will launch the Orion Multi-Purpose Crew Vehicle (MPCV) on its first autonomous flight beyond the Moon and back in December 2017, followed by its first crewed flight in 2021. SLS can evolve to a130t lift capability and serve as a baseline for numerous robotic and human missions ranging from a Mars sample return to delivering the first astronauts to explore another planet. Benefits associated with its unprecedented mass and volume include reduced trip times and simplified payload design. Every SLS element achieved significant, tangible progress over the past year. Among the Program's many accomplishments are: manufacture of core stage test barrels and domes; testing of Solid Rocket Booster development hardware including thrust vector controls and avionics; planning for RS- 25 core stage engine testing; and more than 4,000 wind tunnel runs to refine vehicle configuration, trajectory, and guidance. The Program shipped its first flight hardware - the Multi-Purpose Crew Vehicle Stage Adapter (MSA) - to the United Launch Alliance for integration with the Delta IV heavy rocket that will launch an Orion test article in 2014 from NASA's Kennedy Space Center. The Program successfully completed Preliminary Design Review in 2013 and will complete Key Decision Point C in 2014. NASA has authorized the Program to move forward to Critical Design Review, scheduled for 2015 and a December 2017 first launch. The Program's success to date is due to prudent use of proven technology, infrastructure, and workforce from the Saturn and Space Shuttle programs, a streamlined management

  10. Insights on the National Status of Nuclear Crisis Communication

    Lee, Chang Ju; Hah, Yeon Hee; Oh, Kju Myeng

    2010-01-01

    . By comprehensively searching the national status, we can have a way to establish nuclear risk communication framework for supporting enhancing social acceptance, and clarifying a difference regarding public cognition and information

  11. FUEL HANDLING FACILITY BACKUP CENTRAL COMMUNICATIONS ROOM SPACE REQUIREMENTS CALCULATION

    SZALEWSKI, B.

    2005-01-01

    The purpose of the Fuel Handling Facility Backup Central Communications Room Space Requirements Calculation is to determine a preliminary estimate of the space required to house the backup central communications room in the Fuel Handling Facility (FHF). This room provides backup communications capability to the primary communication systems located in the Central Control Center Facility. This calculation will help guide FHF designers in allocating adequate space for communications system equipment in the FHF. This is a preliminary calculation determining preliminary estimates based on the assumptions listed in Section 4. As such, there are currently no limitations on the use of this preliminary calculation. The calculations contained in this document were developed by Design and Engineering and are intended solely for the use of Design and Engineering in its work regarding the FHF Backup Central Communications Room Space Requirements. Yucca Mountain Project personnel from Design and Engineering should be consulted before the use of the calculations for purposes other than those stated herein or use by individuals other than authorized personnel in Design and Engineering

  12. Status of NASA's Space Launch System

    Honeycutt, John; Lyles, Garry

    2016-01-01

    NASA's Space Launch System (SLS) continued to make significant progress in 2015 and 2016, completing hardware and testing that brings NASA closer to a new era of deep space exploration. Programmatically, SLS completed Critical Design Review (CDR) in 2015. A team of independent reviewers concluded that the vehicle design is technically and programmatically ready to move to Design Certification Review (DCR) and launch readiness in 2018. Just five years after program start, every major element has amassed development and flight hardware and completed key tests that will lead to an accelerated pace of manufacturing and testing in 2016 and 2017. Key to SLS' rapid progress has been the use of existing technologies adapted to the new launch vehicle. The existing fleet of RS-25 engines is undergoing adaptation tests to prove it can meet SLS requirements and environments with minimal change. The four-segment shuttle-era booster has been modified and updated with a fifth propellant segment, new insulation, and new avionics. The Interim Cryogenic Upper Stage is a modified version of an existing upper stage. The first Block I SLS configuration will launch a minimum of 70 metric tons (t) of payload to low Earth orbit (LEO). The vehicle architecture has a clear evolutionary path to more than 100t and, ultimately, to 130t. Among the program's major 2015-2016 accomplishments were two booster qualification hotfire tests, a series of RS-25 adaptation hotfire tests, manufacturing of most of the major components for both core stage test articles and first flight tank, delivery of the Pegasus core stage barge, and the upper stage simulator. Renovations to the B-2 test stand for stage green run testing was completed at NASA Stennis Space Center. This year will see the completion of welding for all qualification and flight EM-1 core stage components and testing of flight avionics, completion of core stage structural test stands, casting of the EM-1 solid rocket motors, additional testing

  13. Free-space communication based on quantum cascade laser

    Liu Chuanwei; Zhai Shenqiang; Zhang Jinchuan; Zhou Yuhong; Jia Zhiwei; Liu Fengqi; Wang Zhanguo

    2015-01-01

    A free-space communication based on a mid-infrared quantum cascade laser (QCL) is presented. A room-temperature continuous-wave distributed-feedback (DFB) QCL combined with a mid-infrared detector comprise the basic unit of the communication system. Sinusoidal signals at a highest frequency of 40 MHz and modulated video signals with a carrier frequency of 30 MHz were successfully transmitted with this experimental setup. Our research has provided a proof-of-concept demonstration of space optical communication application with QCL. The highest operation frequency of our setup was determined by the circuit-limited modulation bandwidth. A high performance communication system can be obtained with improved modulation circuit system. (paper)

  14. Software Defined Radio Architecture Contributions to Next Generation Space Communications

    Kacpura, Thomas J.; Eddy, Wesley M.; Smith, Carl R.; Liebetreu, John

    2015-01-01

    Space communications architecture concepts, comprising the elements of the system, the interactions among them, and the principles that govern their development, are essential factors in developing National Aeronautics and Space Administration (NASA) future exploration and science missions. Accordingly, vital architectural attributes encompass flexibility, the extensibility to insert future capabilities, and to enable evolution to provide interoperability with other current and future systems. Space communications architectures and technologies for this century must satisfy a growing set of requirements, including those for Earth sensing, collaborative observation missions, robotic scientific missions, human missions for exploration of the Moon and Mars where surface activities require supporting communications, and in-space observatories for observing the earth, as well as other star systems and the universe. An advanced, integrated, communications infrastructure will enable the reliable, multipoint, high-data-rate capabilities needed on demand to provide continuous, maximum coverage for areas of concentrated activity. Importantly, the cost/value proposition of the future architecture must be an integral part of its design; an affordable and sustainable architecture is indispensable within anticipated future budget environments. Effective architecture design informs decision makers with insight into the capabilities needed to efficiently satisfy the demanding space-communication requirements of future missions and formulate appropriate requirements. A driving requirement for the architecture is the extensibility to address new requirements and provide low-cost on-ramps for new capabilities insertion, ensuring graceful growth as new functionality and new technologies are infused into the network infrastructure. In addition to extensibility, another key architectural attribute of the space communication equipment's interoperability with other NASA communications

  15. Security Policy for a Generic Space Exploration Communication Network Architecture

    Ivancic, William D.; Sheehe, Charles J.; Vaden, Karl R.

    2016-01-01

    This document is one of three. It describes various security mechanisms and a security policy profile for a generic space-based communication architecture. Two other documents accompany this document- an Operations Concept (OpsCon) and a communication architecture document. The OpsCon should be read first followed by the security policy profile described by this document and then the architecture document. The overall goal is to design a generic space exploration communication network architecture that is affordable, deployable, maintainable, securable, evolvable, reliable, and adaptable. The architecture should also require limited reconfiguration throughout system development and deployment. System deployment includes subsystem development in a factory setting, system integration in a laboratory setting, launch preparation, launch, and deployment and operation in space.

  16. Spectrum Scarcity and Free Space Optical Communications

    Alouini, Mohamed-Slim

    2014-01-06

    Exact and asymptotic studies of the average error probability of wireless communication systems over generalized fading channels have been extensively pursued over the last two decades. In contrast, studies and results dealing with the channel capacity in these environments have been more scarce. In the first part of this talk, we present a generic moment generating function-based approach for the exact computation of the channel capacity in such kind of environments. The resulting formulas are applicable to systems having channel state information (CSI) at the receiver and employing maximal-ratio combining or equal-gain combining multichannel reception. The analysis covers the case where the combined paths are not necessarily independent or identically distributed. In all cases, the proposed approach leads to an expression of the ergodic capacity involving a single finite-range integral, which can be easily computed numerically. In the second part of the talk, we focus on the asymptotic analysis of the capacity in the high and low signal-to-noise ratio (SNR) regimes. More specifically, we offer new simple closed-form formulas that give an intuitive understanding of the capacity behavior at these two extreme regimes. Our characterization covers not only the case where the CSI is available only at the receiver but also the case where the CSI is available at both the transmitter and receiver.

  17. Space Mobile Network: A Near Earth Communication and Navigation Architecture

    Israel, Dave J.; Heckler, Greg; Menrad, Robert J.

    2016-01-01

    This paper describes a Space Mobile Network architecture, the result of a recently completed NASA study exploring architectural concepts to produce a vision for the future Near Earth communications and navigation systems. The Space Mobile Network (SMN) incorporates technologies, such as Disruption Tolerant Networking (DTN) and optical communications, and new operations concepts, such as User Initiated Services, to provide user services analogous to a terrestrial smartphone user. The paper will describe the SMN Architecture, envisioned future operations concepts, opportunities for industry and international collaboration and interoperability, and technology development areas and goals.

  18. Complex networks in the Euclidean space of communicability distances

    Estrada, Ernesto

    2012-06-01

    We study the properties of complex networks embedded in a Euclidean space of communicability distances. The communicability distance between two nodes is defined as the difference between the weighted sum of walks self-returning to the nodes and the weighted sum of walks going from one node to the other. We give some indications that the communicability distance identifies the least crowded routes in networks where simultaneous submission of packages is taking place. We define an index Q based on communicability and shortest path distances, which allows reinterpreting the “small-world” phenomenon as the region of minimum Q in the Watts-Strogatz model. It also allows the classification and analysis of networks with different efficiency of spatial uses. Consequently, the communicability distance displays unique features for the analysis of complex networks in different scenarios.

  19. High & mighty: Implicit associations between space and social status

    Stephanie eGagnon

    2011-10-01

    Full Text Available Figurative language, the built environment, and our perceptuo-motor experiences frequently associate social status with physical space. Linguistic references such as high status or climbing the corporate ladder, and built places such as the U.S. Capitol building link social and physical hierarchies. In three experiments we examine the source and extent of these associations by testing whether people implicitly associate abstract social status indicators with concrete representations of spatial topography (level versus mountainous land and relatively abstract representations of cardinal direction (south and north. Experiment 1 demonstrates speeded performance during an Implicit Association Test (IAT; Greenwald et al., 1998 when average social status is paired with level topography and high status with mountainous topography. Experiments 2 and 3 demonstrate a similar effect but with relatively abstract representations of cardinal direction (south and north, with speeded performance when average and powerful social status are paired with south and north coordinate space, respectively. Abstract concepts of social status are perceived and understood in an inherently spatial world, resulting in powerful associations between abstract social concepts and concrete and abstract notions of physical axes. These associations may prove influential in guiding daily judgments and actions.

  20. Communications among elements of a space construction ensemble

    Davis, Randal L.; Grasso, Christopher A.

    1989-01-01

    Space construction projects will require careful coordination between managers, designers, manufacturers, operators, astronauts, and robots with large volumes of information of varying resolution, timeliness, and accuracy flowing between the distributed participants over computer communications networks. Within the CSC Operations Branch, we are researching the requirements and options for such communications. Based on our work to date, we feel that communications standards being developed by the International Standards Organization, the CCITT, and other groups can be applied to space construction. We are currently studying in depth how such standards can be used to communicate with robots and automated construction equipment used in a space project. Specifically, we are looking at how the Manufacturing Automation Protocol (MAP) and the Manufacturing Message Specification (MMS), which tie together computers and machines in automated factories, might be applied to space construction projects. Together with our CSC industrial partner Computer Technology Associates, we are developing a MAP/MMS companion standard for space construction and we will produce software to allow the MAP/MMS protocol to be used in our CSC operations testbed.

  1. Space transportation systems within ESA programmes: Current status and perspectives

    Delahais, Maurice

    1993-03-01

    An overview of the space transportation aspects of the ESA (European Space Agency) programs as they result from history, present status, and decisions taken at the ministerial level conference in Granada, Spain is presented. The new factors taken into consideration for the long term plan proposed in Munich, Germany, the three strategic options for the reorientation of the ESA long term plan, and the essential elements of space transportation in the Granada long term plan in three areas of space activities, scientific, and commercial launches with expendable launch vehicles, manned flight and in-orbit infrastructure, and future transportation systems are outlined. The new ESA long term plan, in the field of space transportation systems, constitutes a reorientation of the initial program contemplated in previous councils at ministerial level. It aims at balancing the new economic situation with the new avenues of cooperation, and the outcome will be a new implementation of the space transportation systems policy.

  2. Research into command, control, and communications in space construction

    Davis, Randal

    1990-01-01

    Coordinating and controlling large numbers of autonomous or semi-autonomous robot elements in a space construction activity will present problems that are very different from most command and control problems encountered in the space business. As part of our research into the feasibility of robot constructors in space, the CSC Operations Group is examining a variety of command, control, and communications (C3) issues. Two major questions being asked are: can we apply C3 techniques and technologies already developed for use in space; and are there suitable terrestrial solutions for extraterrestrial C3 problems? An overview of the control architectures, command strategies, and communications technologies that we are examining is provided and plans for simulations and demonstrations of our concepts are described.

  3. Emotions under discussion: gender, status and communication in online collaboration.

    Iosub, Daniela; Laniado, David; Castillo, Carlos; Fuster Morell, Mayo; Kaltenbrunner, Andreas

    2014-01-01

    Despite the undisputed role of emotions in teamwork, not much is known about the make-up of emotions in online collaboration. Publicly available repositories of collaboration data, such as Wikipedia editor discussions, now enable the large-scale study of affect and dialogue in peer production. We investigate the established Wikipedia community and focus on how emotion and dialogue differ depending on the status, gender, and the communication network of the [Formula: see text] editors who have written at least 100 comments on the English Wikipedia's article talk pages. Emotions are quantified using a word-based approach comparing the results of two predefined lexicon-based methods: LIWC and SentiStrength. We find that administrators maintain a rather neutral, impersonal tone, while regular editors are more emotional and relationship-oriented, that is, they use language to form and maintain connections to other editors. A persistent gender difference is that female contributors communicate in a manner that promotes social affiliation and emotional connection more than male editors, irrespective of their status in the community. Female regular editors are the most relationship-oriented, whereas male administrators are the least relationship-focused. Finally, emotional and linguistic homophily is prevalent: editors tend to interact with other editors having similar emotional styles (e.g., editors expressing more anger connect more with one another). Emotional expression and linguistic style in online collaboration differ substantially depending on the contributors' gender and status, and on the communication network. This should be taken into account when analyzing collaborative success, and may prove insightful to communities facing gender gap and stagnation in contributor acquisition and participation levels.

  4. Scholarly communication, scholarly publication and the status of emerging formats

    Leah Halliday

    2001-01-01

    Full Text Available A study was carried out to clarify the term 'scholarly publication' and to explore the role of this activity in the scholarly communication process. Desk research was supplemented by responses to a questionnaire from key figures in the development of emerging scholarly communicative behaviours. This facilitated development of a working definition of scholarly publication consisting of a list of criteria. These may be used to analyse the degree to which emerging formats can be categorised as scholarly publications and to identify the means by which these formats may be supplemented so that their status may be promoted to that of ‘scholarly publication’, i.e., documents that meet all of the publication needs of scholarly communities.

  5. Research on optic antenna of space laser communication networking

    Meng, Li-Xin; Li, Long; Zhang, Li-zhong; Zhao, Shan-shan; Jiang, Hui-lin

    2013-08-01

    With the highlights of the high transmission rate, large capacity, strong anti-interference and anti-capture ability, good security and small light, space laser communication becomes an important hotspot. At present, the focus of research of the laser communication system is point to point communication structure. However, from the application point of view, both the realization of space laser communication among multiple points and the establishment of the information transmission network can really have the practical value. Aiming at the problem of space laser communication network, this article puts forward the general idea about optical antenna to achieve multiple tracking goals at the same time. Through the analysis of the optical antenna, and the comparing of the current commonly used mirror driving mechanism, a new mirror driving mechanism is designed. The azimuth motion, containing circular grating feedback, is driven by torque motor,voice coil motor of fan produces pitch motion that has fan-shaped grating feedback, so that compression of the structure size to improve the efficiency of the reflector assembly. Through the establishment of the driving mechanism and the kinematic model of 3D entity, the relationship between the single drive azimuth and pitch angle following the angle of incident light is explained. The biggest ideal view area affecting the optical antenna is obtained by the simulation analysis of the kinematics model using MATLAB. The several factors of field overlap area and blind area offers a theoretical basis for structure optimization and control system for the subsequent optical antenna design.

  6. Free Space Optics Communication for Mobile Military Platforms

    2003-12-01

    Federal Communications Commission FDA Food and Drug Administration FOV Field-of-View FSO Free Space Optics FWHM Full Width at Half Maximum Gbps...Physique et de Métrologie des Oscillateurs (LPMO) du CNRS UPR3203, associé à l’Université de Franche -Comté, 15 March 2002 [Schenk 2000] H. Schenk

  7. Robust free-space optical communication for indoor information environment

    Nakada, Toyohisa; Itoh, Hideo; Kunifuji, Susumu; Nakashima, Hideyuki

    2003-10-01

    The purpose of our study is to establish a robust communication, while keeping security and privacy, between a handheld communicator and the surrounding information environment. From the viewpoint of low power consumption, we have been developing a reflectivity modulating communication module composed of a liquid crystal light modulator and a corner-reflecting mirror sheet. We installed a corner-reflecting sheet instead of light scattering sheet in a handheld videogame machine with a display screen with a reflection-type liquid crystal. Infrared (IR) LED illuminator attached next to the IR camera of a base station illuminates all the room, and the terminal send their data to the base station by switching ON and OFF of the reflected IR beam. Intensity of reflected light differs with the position and the direction of the terminal, and sometimes the intensity of OFF signal at a certain condition is brighter than that of ON signal at another condition. To improve the communication quality, use of machine learning technique is a possibility of the solution. In this paper, we compare various machine learning techniques for the purpose of free space optical communication, and propose a new algorithm that improves the robustness of the data link. Evaluation using an actual free-space communication system is also described.

  8. The Status of Development of Electromagnetic Pumps for Space Application

    Kwak, J. S.; Kim, K. H.; Jeong, J. S.; Kim, Hee Reyoung

    2013-01-01

    Korea lunched this research as a part of the small nuclear power generation technology development for space. In this study, investigated are the basic principle and types of electromagnetic pump and the trend of electromagnetic pump technology development in foreign nations. The survey and analysis give the understanding of the suitability and prospect of electromagnetic pumps as space application technology in Korea. The analysis on the status of the development of electromagnetic pumps was carried out for the application to space environment. It was found that USA was approaching the research and development of electromagnetic pumps for space application. Most electromagnetic pumps surveyed have the efficiency between 35% and 50% where that of AC conduction pump is less than 6%. Further study was thought to have to be given for the mechanical and material characteristics, and the applicability of electromagnetic pumps for space nuclear reactor

  9. SPACE COMMUNICATION AND THE MASS MEDIA. A UNESCO REPORT ON THE OCCASION OF THE 1963 SPACE COMMUNICATIONS CONFERENCE. REPORTS AND PAPERS ON MASS COMMUNICATION.

    United Nations Educational, Scientific, and Cultural Organization, Paris (France).

    THIS REPORT DEFINES AND ANALYZES POTENTIAL ASPECTS OF WORLDWIDE COMMUNICATION BY SATELLITE, LISTS TECHNICAL PROBLEMS, AND SUGGESTS USES OF SPACE COMMUNICATION TO PROMOTE EDUCATION, CULTURAL EXCHANGE, AND INFORMATION FLOW. IT IS AVAILABLE FOR $0.50 FROM NATIONAL DISTRIBUTORS OF UNESCO PUBLICATIONS, OR FROM UNESCO, PLACE DE FONTENDOY, PARIS-7E,…

  10. Research progress of free space coherent optical communication

    Tan, Zhenkun; Ke, Xizheng

    2018-02-01

    This paper mainly introduces the research progress of free space coherent optical communication in Xi'an University of Technology. In recent years, the research on the outer modulation technology of the laser, free-space-to-fiber coupling technique, the design of transmitting and receiving optical antenna, adaptive optical technology with or without wave-front sensor, automatic polarization control technology, frequency stabilization technology, heterodyne detection technology and high speed signal processing technology. Based on the above related research, the digital signal modulation, transmission, detection and data recovery are realized by the heterodyne detection technology in the free space optical communication system, and finally the function of smooth viewing high-definition video is realized.

  11. Overview of some projects of SNPS for global space communication

    Ivanov, E.; Ghitaykin, V.; Ionkin, V.; Dubinin, A.; Pyshko, A.

    2001-01-01

    In this presentation we focused on three variants of prospective concepts of SNPS. They are intended to solve tasks of global space communication (GSC) as nearest future tasks in space. Modern concepts of the application of power technology in space believe in using an onboard source of energy for maintenance of self-transportation of the vehicle into geostationary orbit (GSO). There are three more prospective systems as follows: gas cooled nuclear reactor with hybrid thermal engine and machine power converter; nuclear reactor cooled by liquid metal and with a thermoelectric power generating system; nuclear reactor with Li cooling and a thermionic and thermoelectric power generator on board. The choice of a concept must fit strong requirements such as: space nuclear power unit is aimed to be used in a powerful mission; space power unit must be able to maintain the dual - mode regime of vehicle operation (self - transportation and long life in geosynchronous orbit [GEO]); nuclear rector of unit must be safety and it must be designed in such a way that it will ensure minimum size of the complete system; the elements of the considered technology can be used for the creation of NPPI and with other sources of heat (for example, radioisotope); the degree of technical and technological readiness of units of the thermal and power circuit of installation is estimated to be high and is defined by a number of technological developments in air, space and nuclear branches; nuclear reactor and heat transfer equipment should work in a normal mode, which can be very reliably confirmed for other high-temperature nuclear systems. Considering these concepts we practically consider one of possible strategy of developing of complex system of nuclear power engineering. It is the strategy of step-by-step development of space engineering with real application of them in commercial, scientific and other powerful missions in the nearest and deep space. As starting point of this activity is

  12. An Introduction to Free-space Optical Communications

    H. Henniger

    2010-06-01

    Full Text Available Over the last two decades free-space optical communication (FSO has become more and more interesting as an adjunct or alternative to radio frequency communication. This article gives an overview of the challenges a system designer has to consider while implementing an FSO system. Typical gains and losses along the path from the transmitter through the medium to the receiver are introduced in this article. Detailed discussions of these topics can be found in this special issue of the Radioengineering Journal.

  13. Distress detection, location, and communications using advanced space technology

    Sivertson, W. E., Jr.

    1977-01-01

    This paper briefly introduces a concept for low-cost, global, day-night, all-weather disaster warning and assistance. Evolving, advanced space technology with passive radio frequency reflectors in conjunction with an imaging synthetic aperture radar is employed to detect, identify, locate, and provide passive communication with earth users in distress. This concept evolved from a broad NASA research on new global search and rescue techniques. Appropriate airborne radar test results from this research are reviewed and related to potential disaster applications. The analysis indicates the approach has promise for disaster communications relative to floods, droughts, earthquakes, volcanic eruptions, and severe storms.

  14. Laser guide stars for optical free-space communications

    Mata-Calvo, Ramon; Bonaccini Calia, Domenico; Barrios, Ricardo; Centrone, Mauro; Giggenbach, Dirk; Lombardi, Gianluca; Becker, Peter; Zayer, Igor

    2017-02-01

    The German Aerospace Center (DLR) and the European Southern Observatory (ESO) performed a measurement campaign together in April and July 2016 at Teide-Observatory (Tenerife), with the support of the European Space Agency (ESA), to investigate the use of laser guide stars (LGS) in ground to space optical communications. Atmospheric turbulence causes strong signal fluctuations in the uplink, due to scintillation and beam wander. In space communications, the use of the downlink channel as reference for pointing and for pre-distortion adaptive optics is limited by the size of the isokinetic and isoplanatic angle in relation to the required point-ahead angle. Pointing and phase errors due to the decorrelation between downward and upward beam due to the point-ahead angle may have a severe impact on the required transmit power and the stability of the communications link. LGSs provide a self-tailored reference to any optical ground-to-space link, independently of turbulence conditions and required point-ahead angle. In photon-starved links, typically in deep-space scenarios, LGSs allow dedicating all downlink received signal to communications purposes, increasing the available link margin. The scope of the joint DLR-ESO measurement campaign was, first, to measure the absolute value of the beam wander (uplink-tilt) using a LGS, taking a natural star as a reference, and, second, to characterize the decrease of correlation between uplink-tilt and downlink-tilt with respect to the angular separation between both sources. This paper describes the experiments performed during the measurement campaigns, providing an overview of the measured data and the first outcomes of the data post-processing.

  15. Applying Model Based Systems Engineering to NASA's Space Communications Networks

    Bhasin, Kul; Barnes, Patrick; Reinert, Jessica; Golden, Bert

    2013-01-01

    System engineering practices for complex systems and networks now require that requirement, architecture, and concept of operations product development teams, simultaneously harmonize their activities to provide timely, useful and cost-effective products. When dealing with complex systems of systems, traditional systems engineering methodology quickly falls short of achieving project objectives. This approach is encumbered by the use of a number of disparate hardware and software tools, spreadsheets and documents to grasp the concept of the network design and operation. In case of NASA's space communication networks, since the networks are geographically distributed, and so are its subject matter experts, the team is challenged to create a common language and tools to produce its products. Using Model Based Systems Engineering methods and tools allows for a unified representation of the system in a model that enables a highly related level of detail. To date, Program System Engineering (PSE) team has been able to model each network from their top-level operational activities and system functions down to the atomic level through relational modeling decomposition. These models allow for a better understanding of the relationships between NASA's stakeholders, internal organizations, and impacts to all related entities due to integration and sustainment of existing systems. Understanding the existing systems is essential to accurate and detailed study of integration options being considered. In this paper, we identify the challenges the PSE team faced in its quest to unify complex legacy space communications networks and their operational processes. We describe the initial approaches undertaken and the evolution toward model based system engineering applied to produce Space Communication and Navigation (SCaN) PSE products. We will demonstrate the practice of Model Based System Engineering applied to integrating space communication networks and the summary of its

  16. Mixed Integer Programming and Heuristic Scheduling for Space Communication

    Lee, Charles H.; Cheung, Kar-Ming

    2013-01-01

    Optimal planning and scheduling for a communication network was created where the nodes within the network are communicating at the highest possible rates while meeting the mission requirements and operational constraints. The planning and scheduling problem was formulated in the framework of Mixed Integer Programming (MIP) to introduce a special penalty function to convert the MIP problem into a continuous optimization problem, and to solve the constrained optimization problem using heuristic optimization. The communication network consists of space and ground assets with the link dynamics between any two assets varying with respect to time, distance, and telecom configurations. One asset could be communicating with another at very high data rates at one time, and at other times, communication is impossible, as the asset could be inaccessible from the network due to planetary occultation. Based on the network's geometric dynamics and link capabilities, the start time, end time, and link configuration of each view period are selected to maximize the communication efficiency within the network. Mathematical formulations for the constrained mixed integer optimization problem were derived, and efficient analytical and numerical techniques were developed to find the optimal solution. By setting up the problem using MIP, the search space for the optimization problem is reduced significantly, thereby speeding up the solution process. The ratio of the dimension of the traditional method over the proposed formulation is approximately an order N (single) to 2*N (arraying), where N is the number of receiving antennas of a node. By introducing a special penalty function, the MIP problem with non-differentiable cost function and nonlinear constraints can be converted into a continuous variable problem, whose solution is possible.

  17. Radio-wave propagation for space communications systems

    Ippolito, L. J.

    1981-01-01

    The most recent information on the effects of Earth's atmosphere on space communications systems is reviewed. The design and reliable operation of satellite systems that provide the many applications in space which rely on the transmission of radio waves for communications and scientific purposes are dependent on the propagation characteristics of the transmission path. The presence of atmospheric gases, clouds, fog, precipitation, and turbulence causes uncontrolled variations in the signal characteristics. These variations can result in a reduction of the quality and reliability of the transmitted information. Models and other techniques are used in the prediction of atmospheric effects as influenced by frequency, geography, elevation angle, and type of transmission. Recent data on performance characteristics obtained from direct measurements on satellite links operating to above 30 GHz have been reviewed. Particular emphasis has been placed on the effects of precipitation on the Earth/space path, including rain attenuation, and ice particle depolarization. Other factors are sky noise, antenna gain degradation, scintillations, and bandwidth coherence. Each of the various propagation factors has an effect on design criteria for communications systems. These criteria include link reliability, power margins, noise contribution, modulation and polarization factors, channel cross talk, error rate, and bandwidth limitations.

  18. Space Mobile Network: A Near Earth Communications and Navigation Architecture

    Israel, David J.; Heckler, Gregory W.; Menrad, Robert J.

    2016-01-01

    This paper shares key findings of NASA's Earth Regime Network Evolution Study (ERNESt) team resulting from its 18-month effort to define a wholly new architecture-level paradigm for the exploitation of space by civil space and commercial sector organizations. Since the launch of Sputnik in October 1957 spaceflight missions have remained highly scripted activities from launch through disposal. The utilization of computer technology has enabled dramatic increases in mission complexity; but, the underlying premise that the diverse actions necessary to meet mission goals requires minute-by-minute scripting, defined weeks in advance of execution, for the life of the mission has remained. This archetype was appropriate for a "new frontier" but now risks overtly constraining the potential market-based opportunities for the innovation considered necessary to efficiently address the complexities associated with meeting communications and navigation requirements projected to be characteristics of the next era of space exploration: a growing number of missions in simultaneous execution, increased variance of mission types and growth in location/orbital regime diversity. The resulting ERNESt architectural cornerstone - the Space Mobile Network (SMN) - was envisioned as critical to creating an environment essential to meeting these future challenges in political, programmatic, technological and budgetary terms. The SMN incorporates technologies such as: Disruption Tolerant Networking (DTN) and optical communications, as well as new operations concepts such as User Initiated Services (UIS) to provide user services analogous to today's terrestrial mobile network user. Results developed in collaboration with NASA's Space Communications and Navigation (SCaN) Division and field centers are reported on. Findings have been validated via briefings to external focus groups and initial ground-based demonstrations. The SMN opens new niches for exploitation by the marketplace of mission

  19. High-capacity Free-space Optical Communications with Orbital Angular Momentum

    National Aeronautics and Space Administration — As the demand for high data returns from space science missions continues, significant improvements over the current radiofrequency (RF) communications architectures...

  20. Monolithic Microwave Integrated Circuit (MMIC) technology for space communications applications

    Connolly, Denis J.; Bhasin, Kul B.; Romanofsky, Robert R.

    1987-01-01

    Future communications satellites are likely to use gallium arsenide (GaAs) monolithic microwave integrated-circuit (MMIC) technology in most, if not all, communications payload subsystems. Multiple-scanning-beam antenna systems are expected to use GaAs MMIC's to increase functional capability, to reduce volume, weight, and cost, and to greatly improve system reliability. RF and IF matrix switch technology based on GaAs MMIC's is also being developed for these reasons. MMIC technology, including gigabit-rate GaAs digital integrated circuits, offers substantial advantages in power consumption and weight over silicon technologies for high-throughput, on-board baseband processor systems. For the more distant future pseudomorphic indium gallium arsenide (InGaAs) and other advanced III-V materials offer the possibility of MMIC subsystems well up into the millimeter wavelength region. All of these technology elements are in NASA's MMIC program. Their status is reviewed.

  1. Development of the Free-space Optical Communications Analysis Software (FOCAS)

    Jeganathan, M.; Mecherle, G.; Lesh, J.

    1998-01-01

    The Free-space Optical Communications Analysis Software (FOCAS) was developed at the Jet Propulsion Laboratory (JPL) to provide mission planners, systems engineers and communications engineers with an easy to use tool to analyze optical communications link.

  2. Free-Space Quantum Communication with a Portable Quantum Memory

    Namazi, Mehdi; Vallone, Giuseppe; Jordaan, Bertus; Goham, Connor; Shahrokhshahi, Reihaneh; Villoresi, Paolo; Figueroa, Eden

    2017-12-01

    The realization of an elementary quantum network that is intrinsically secure and operates over long distances requires the interconnection of several quantum modules performing different tasks. In this work, we report the realization of a communication network functioning in a quantum regime, consisting of four different quantum modules: (i) a random polarization qubit generator, (ii) a free-space quantum-communication channel, (iii) an ultralow-noise portable quantum memory, and (iv) a qubit decoder, in a functional elementary quantum network possessing all capabilities needed for quantum-information distribution protocols. We create weak coherent pulses at the single-photon level encoding polarization states |H ⟩ , |V ⟩, |D ⟩, and |A ⟩ in a randomized sequence. The random qubits are sent over a free-space link and coupled into a dual-rail room-temperature quantum memory and after storage and retrieval are analyzed in a four-detector polarization analysis akin to the requirements of the BB84 protocol. We also show ultralow noise and fully portable operation, paving the way towards memory-assisted all-environment free-space quantum cryptographic networks.

  3. Intensity position modulation for free-space laser communication system

    Jangjoo, Alireza; Faghihi, F.

    2004-12-01

    In this research a novel modulation technique for free-space laser communication system called Intensity Position Modulation (IPM) is carried out. According to TEM00 mode of a laser beam and by linear fitting on the Gaussian function as an approximation, the variation of linear part on the reverse biased pn photodiode produced alternating currents which contain the information. Here, no characteristic property of the beam as intensity or frequency is changed and only the beam position moves laterally. We demonstrated that in this method no bandwidth is required, so it is possible to reduce the background radiation noise by narrowband filtering of the carrier. The fidelity of the analog voice communication system which is made upon the IPM is satisfactory and we are able to transmit the audio signals up to 1Km.

  4. Applications of Microwave Photonics in Radio Astronomy and Space Communication

    D'Addario, Larry R.; Shillue, William P.

    2006-01-01

    An overview of narrow band vs wide band signals is given. Topics discussed included signal transmission, reference distribution and photonic antenna metrology. Examples of VLA, ALMA, ATA and DSN arrays are given. . Arrays of small antennas have become more cost-effective than large antennas for achieving large total aperture or gain, both for astronomy and for communication. It is concluded that emerging applications involving arrays of many antennas require low-cost optical communication of both wide bandwidth and narrow bandwidth; development of round-trip correction schemes enables timing precision; and free-space laser beams with microwave modulation allow structural metrology with approx 100 micrometer precision over distances of 200 meters.

  5. Organizing for low cost space operations - Status and plans

    Lee, C.

    1976-01-01

    Design features of the Space Transportation System (vehicle reuse, low cost expendable components, simple payload interfaces, standard support systems) must be matched by economical operational methods to achieve low operating and payload costs. Users will be responsible for their own payloads and will be charged according to the services they require. Efficient use of manpower, simple documentation, simplified test, checkout, and flight planning are firm goals, together with flexibility for quick response to varying user needs. Status of the Shuttle hardware, plans for establishing low cost procedures, and the policy for user charges are discussed.

  6. Planets as background noise sources in free space optical communications

    Katz, J.

    1986-01-01

    Background noise generated by planets is the dominant noise source in most deep space direct detection optical communications systems. Earlier approximate analyses of this problem are based on simplified blackbody calculations and can yield results that may be inaccurate by up to an order of magnitude. Various other factors that need to be taken into consideration, such as the phase angle and the actual spectral dependence of the planet albedo, in order to obtain a more accurate estimate of the noise magnitude are examined.

  7. Video semaphore decoding for free-space optical communication

    Last, Matthew; Fisher, Brian; Ezekwe, Chinwuba; Hubert, Sean M.; Patel, Sheetal; Hollar, Seth; Leibowitz, Brian S.; Pister, Kristofer S. J.

    2001-04-01

    Using teal-time image processing we have demonstrated a low bit-rate free-space optical communication system at a range of more than 20km with an average optical transmission power of less than 2mW. The transmitter is an autonomous one cubic inch microprocessor-controlled sensor node with a laser diode output. The receiver is a standard CCD camera with a 1-inch aperture lens, and both hardware and software implementations of the video semaphore decoding algorithm. With this system sensor data can be reliably transmitted 21 km form San Francisco to Berkeley.

  8. Space station communications and tracking equipment management/control system

    Kapell, M. H.; Seyl, J. W.

    1982-01-01

    Design details of a communications and tracking (C and T) local area network and the distribution system requirements for the prospective space station are described. The hardware will be constructed of LRUs, including those for baseband, RF, and antenna subsystems. It is noted that the C and T equipment must be routed throughout the station to accommodate growth of the station. Configurations of the C and T modules will therefore be dependent on the function of the space station module where they are located. A block diagram is provided of a sample C and T hardware distribution configuration. A topology and protocol will be needed to accommodate new terminals, wide bandwidths, bidirectional message transmission, and distributed functioning. Consideration will be given to collisions occurring in the data transmission channels.

  9. Challenges for deep space communications in the 1990s

    Dumas, Larry N.; Hornstein, Robert M.

    1991-01-01

    The discussion of NASA's Deep Space Network (DSN) examines the evolving character of aerospace missions and the corresponding changes in the DSN architecture. Deep space missions are reviewed, and it is noted that the two 34-m and the 70-m antenna subnets of the DSN are heavily loaded and more use is expected. High operational workload and the challenge of network cross-support are the design drivers for a flexible DSN architecture configuration. Incorporated in the design are antenna arraying for aperture augmentation, beam-waveguide antennas for frequency agility, and connectivity with non-DSN sites for cross-support. Compatibility between spacecraft and ground-facility designs is important for establishing common international standards of communication and data-system specification.

  10. Architecture for Cognitive Networking within NASAs Future Space Communications Infrastructure

    Clark, Gilbert J., III; Eddy, Wesley M.; Johnson, Sandra K.; Barnes, James; Brooks, David

    2016-01-01

    Future space mission concepts and designs pose many networking challenges for command, telemetry, and science data applications with diverse end-to-end data delivery needs. For future end-to-end architecture designs, a key challenge is meeting expected application quality of service requirements for multiple simultaneous mission data flows with options to use diverse onboard local data buses, commercial ground networks, and multiple satellite relay constellations in LEO, MEO, GEO, or even deep space relay links. Effectively utilizing a complex network topology requires orchestration and direction that spans the many discrete, individually addressable computer systems, which cause them to act in concert to achieve the overall network goals. The system must be intelligent enough to not only function under nominal conditions, but also adapt to unexpected situations, and reorganize or adapt to perform roles not originally intended for the system or explicitly programmed. This paper describes architecture features of cognitive networking within the future NASA space communications infrastructure, and interacting with the legacy systems and infrastructure in the meantime. The paper begins by discussing the need for increased automation, including inter-system collaboration. This discussion motivates the features of an architecture including cognitive networking for future missions and relays, interoperating with both existing endpoint-based networking models and emerging information-centric models. From this basis, we discuss progress on a proof-of-concept implementation of this architecture as a cognitive networking on-orbit application on the SCaN Testbed attached to the International Space Station.

  11. Architecture for Cognitive Networking within NASA's Future Space Communications Infrastructure

    Clark, Gilbert; Eddy, Wesley M.; Johnson, Sandra K.; Barnes, James; Brooks, David

    2016-01-01

    Future space mission concepts and designs pose many networking challenges for command, telemetry, and science data applications with diverse end-to-end data delivery needs. For future end-to-end architecture designs, a key challenge is meeting expected application quality of service requirements for multiple simultaneous mission data flows with options to use diverse onboard local data buses, commercial ground networks, and multiple satellite relay constellations in LEO, GEO, MEO, or even deep space relay links. Effectively utilizing a complex network topology requires orchestration and direction that spans the many discrete, individually addressable computer systems, which cause them to act in concert to achieve the overall network goals. The system must be intelligent enough to not only function under nominal conditions, but also adapt to unexpected situations, and reorganize or adapt to perform roles not originally intended for the system or explicitly programmed. This paper describes an architecture enabling the development and deployment of cognitive networking capabilities into the envisioned future NASA space communications infrastructure. We begin by discussing the need for increased automation, including inter-system discovery and collaboration. This discussion frames the requirements for an architecture supporting cognitive networking for future missions and relays, including both existing endpoint-based networking models and emerging information-centric models. From this basis, we discuss progress on a proof-of-concept implementation of this architecture, and results of implementation and initial testing of a cognitive networking on-orbit application on the SCaN Testbed attached to the International Space Station.

  12. Superconducting Nanowire Single Photon Detectors for High-Data-Rate Deep-Space Optical Communication

    National Aeronautics and Space Administration — High data rate deep space optical communication (DSOC) links for manned and unmanned space exploration have been identified by NASA as a critical future capability,...

  13. Quantum cryptography for secure free-space communications

    Hughes, R.J.; Buttler, W.T.; Kwiat, P.G.; Lamoreaux, S.K.; Luther, G.G.; Morgan, G.L.; Nordholt, J.E.; Peterson, C.G.

    1999-01-01

    The secure distribution of the secret random bit sequences known as key material, is an essential precursor to their use for the encryption and decryption of confidential communications. Quantum cryptography is a new technique for secure key distribution with single-photon transmissions: Heisenberg's uncertainty principle ensures that an adversary can neither successfully tap the key transmissions, nor evade detection (eavesdropping raises the key error rate above a threshold value). The authors have developed experimental quantum cryptography systems based on the transmission of non-orthogonal photon polarization states to generate shared key material over line-of-sight optical links. Key material is built up using the transmission of a single-photon per bit of an initial secret random sequence. A quantum-mechanically random subset of this sequence is identified, becoming the key material after a data reconciliation stage with the sender. The authors have developed and tested a free-space quantum key distribution (QKD) system over an outdoor optical path of ∼1 km at Los Alamos National Laboratory under nighttime conditions. Results show that free-space QKD can provide secure real-time key distribution between parties who have a need to communicate secretly. Finally, they examine the feasibility of surface to satellite QKD

  14. Novel Photon-Counting Detectors for Free-Space Communication

    Krainak, Michael A.; Yang, Guan; Sun, Xiaoli; Lu, Wei; Merritt, Scott; Beck, Jeff

    2016-01-01

    We present performance data for novel photon counting detectors for free space optical communication. NASA GSFC is testing the performance of three novel photon counting detectors 1) a 2x8 mercury cadmium telluride avalanche array made by DRS Inc. 2) a commercial 2880 silicon avalanche photodiode array and 3) a prototype resonant cavity silicon avalanche photodiode array. We will present and compare dark count, photon detection efficiency, wavelength response and communication performance data for these detectors. We discuss system wavelength trades and architectures for optimizing overall communication link sensitivity, data rate and cost performance. The HgCdTe APD array has photon detection efficiencies of greater than 50 were routinely demonstrated across 5 arrays, with one array reaching a maximum PDE of 70. High resolution pixel-surface spot scans were performed and the junction diameters of the diodes were measured. The junction diameter was decreased from 31 m to 25 m resulting in a 2x increase in e-APD gain from 470 on the 2010 array to 1100 on the array delivered to NASA GSFC. Mean single photon SNRs of over 12 were demonstrated at excess noise factors of 1.2-1.3.The commercial silicon APD array has a fast output with rise times of 300ps and pulse widths of 600ps. Received and filtered signals from the entire array are multiplexed onto this single fast output. The prototype resonant cavity silicon APD array is being developed for use at 1 micron wavelength.

  15. Update on the Status of the Space Telescope Imaging Spectrograph onboard the Hubble Space Telescope

    Hernandez, Svea; Aloisi, A.; Bostroem, K. A.; Cox, C.; Debes, J. H.; DiFelice, A.; Roman-Duval, J.; Hodge, P.; Holland, S.; Lindsay, K.; Lockwood, S. A.; Mason, E.; Oliveira, C. M.; Penton, S. V.; Proffitt, C. R.; Sonnentrucker, P.; Taylor, J. M.; Wheeler, T.

    2013-06-01

    The Space Telescope Imaging Spectrograph (STIS) has been on orbit for approximately 16 years as one of the 2nd generation instruments on the Hubble Space Telescope (HST). Its operations were interrupted by an electronics failure in 2004, but STIS was successfully repaired in May 2009 during Service Mission 4 (SM4) allowing it to resume science observations. The Instrument team continues to monitor its performance and work towards improving the quality of its products. Here we present updated information on the status of the FUV and NUV MAMA and the CCD detectors onboard STIS and describe recent changes to the STIS calibration pipeline. We also discuss the status of efforts to apply a pixel-based correction for charge transfer inefficiency (CTI) effects to STIS CCD data. These techniques show promise for ameliorating the effects of ongoing radiation damage on the quality of STIS CCD data.

  16. Secure space-to-space interferometric communications and its nexus to the physics of quantum entanglement

    Duarte, F. J.

    2016-12-01

    The history of the probability amplitude equation | ψ > = ( | x , y > - | y , x > ) applicable to quanta pairs, propagating in different directions with entangled polarizations, is reviewed and traced back to the 1947-1949 period. The interferometric Dirac foundations common to | ψ > = ( | x , y > - | y , x > ) and the generalized N-slit interferometric equation, for indistinguishable quanta, are also described. The results from a series of experiments on N-slit laser interferometers, with intra interferometric propagation paths up to 527 m, are reviewed. Particular attention is given to explain the generation of interferometric characters, for secure space-to-space communications, which immediately collapse on attempts of interception. The design of a low divergence N-slit laser interferometer for low Earth orbit-low Earth orbit (LEO-LEO), and LEO-geostationary Earth orbit (LEO-GEO), secure interferometric communications is described and a weight assessment is provided.

  17. Internet Technologies for Space-based Communications: State of the Art and Challenges

    Bhasin, K.; DePaula, R.; Edwards, C.

    2000-01-01

    The Internet is rapidly changing the ways we communicate information around the globe today. The desire to provide Internet-based services to anyone, anywhere, anytime has brought satellite communications to the forefront to become an integral part of the Internet. In spite of the distances involved, satellite links are proving to be capable of providing Internet services based on Internet protocol (TCP/IP) stack. This development has led to the question particularly at NASA; can satellites and other space platforms become an Internet-node in space? This will allow the direct transfer of information directly from space to the users on Earth and even be able to control the spacecraft and its instruments. NASA even wants to extend the near earth space Internet to deep space applications where scientists and the public here on Earth may view space exploration in real time via the Internet. NASA's future solar system exploration will involve intensive in situ investigations of planets, moons, asteroids, and comets. While past missions typically involved a single fly-by or orbiting science spacecraft, future missions will begin to use fleets of small, highly intelligent robotic vehicles to carry out collaborative investigations. The resulting multi-spacecraft topologies will effectively create a wide area network spanning the solar system. However, this will require significant development in Internet technologies for space use. This paper provides the status'of the Internet for near earth applications and the potential extension of the Internet for use in deep space planetary exploration. The paper will discuss the overall challenges of implementing the space Internet and how the space Internet will integrate into the complex terrestrial systems those forms the Internet of today in a hybrid set of networks. Internet. We envision extending to the deep space environment such Internet concepts as a well-designed layered architecture. This effort will require an ability to

  18. Research on Retro-reflecting Modulation in Space Optical Communication System

    Zhu, Yifeng; Wang, Guannan

    2018-01-01

    Retro-reflecting modulation space optical communication is a new type of free space optical communication technology. Unlike traditional free space optical communication system, it applys asymmetric optical systems to reduce the size, weight and power consumption of the system and can effectively solve the limits of traditional free space optical communication system application, so it can achieve the information transmission. This paper introduces the composition and working principle of retro-reflecting modulation optical communication system, analyzes the link budget of this system, reviews the types of optical system and optical modulator, summarizes this technology future research direction and application prospects.

  19. Precoded generalized space shift keying for indoor visible light communications

    Kadampot, Ishaque Ashar

    2014-09-01

    We consider a visible light communication system with 2 transmit light emitting diodes (LED) and nr receive photodiodes. An optical generalized space shift keying modulation scheme is considered for the transmission of bits where each LED can be either in ON state or OFF state at a given time. With this set-up, we design in this paper a precoder for this modulation scheme given the channel state information to improve the bit error rate performance of the system. As conventional precoding techniques for radio frequency at the transmitter cannot be applied to the optical intensity channel, we formulate an optimization problem with constraints for this specific channel. An analytical solution for the precoder is derived and the system performance is compared with and without precoder.

  20. Precision time distribution within a deep space communications complex

    Curtright, J. B.

    1972-01-01

    The Precision Time Distribution System (PTDS) at the Golstone Deep Space Communications Complex is a practical application of existing technology to the solution of a local problem. The problem was to synchronize four station timing systems to a master source with a relative accuracy consistently and significantly better than 10 microseconds. The solution involved combining a precision timing source, an automatic error detection assembly and a microwave distribution network into an operational system. Upon activation of the completed PTDS two years ago, synchronization accuracy at Goldstone (two station relative) was improved by an order of magnitude. It is felt that the validation of the PTDS mechanization is now completed. Other facilities which have site dispersion and synchronization accuracy requirements similar to Goldstone may find the PTDS mechanization useful in solving their problem. At present, the two station relative synchronization accuracy at Goldstone is better than one microsecond.

  1. An Array of Optical Receivers for Deep-Space Communications

    Vilnrotter, Chi-Wung; Srinivasan, Meera; Andrews, Kenneth

    2007-01-01

    An array of small optical receivers is proposed as an alternative to a single large optical receiver for high-data-rate communications in NASA s Deep Space Network (DSN). Because the telescope for a single receiver capable of satisfying DSN requirements must be greater than 10 m in diameter, the design, building, and testing of the telescope would be very difficult and expensive. The proposed array would utilize commercially available telescopes of 1-m or smaller diameter and, therefore, could be developed and verified with considerably less difficulty and expense. The essential difference between a single-aperture optical-communications receiver and an optical-array receiver is that a single-aperture receiver focuses all of the light energy it collects onto the surface of an optical detector, whereas an array receiver focuses portions of the total collected energy onto separate detectors, optically detects each fractional energy component, then combines the electrical signal from the array of detector outputs to form the observable, or "decision statistic," used to decode the transmitted data. A conceptual block diagram identifying the key components of the optical-array receiver suitable for deep-space telemetry reception is shown in the figure. The most conspicuous feature of the receiver is the large number of small- to medium-size telescopes, with individual apertures and number of telescopes selected to make up the desired total collecting area. This array of telescopes is envisioned to be fully computer- controlled via the user interface and prediction-driven to achieve rough pointing and tracking of the desired spacecraft. Fine-pointing and tracking functions then take over to keep each telescope pointed toward the source, despite imperfect pointing predictions, telescope-drive errors, and vibration caused by wind.

  2. Fast QC-LDPC code for free space optical communication

    Wang, Jin; Zhang, Qi; Udeh, Chinonso Paschal; Wu, Rangzhong

    2017-02-01

    Free Space Optical (FSO) Communication systems use the atmosphere as a propagation medium. Hence the atmospheric turbulence effects lead to multiplicative noise related with signal intensity. In order to suppress the signal fading induced by multiplicative noise, we propose a fast Quasi-Cyclic (QC) Low-Density Parity-Check (LDPC) code for FSO Communication systems. As a linear block code based on sparse matrix, the performances of QC-LDPC is extremely near to the Shannon limit. Currently, the studies on LDPC code in FSO Communications is mainly focused on Gauss-channel and Rayleigh-channel, respectively. In this study, the LDPC code design over atmospheric turbulence channel which is nether Gauss-channel nor Rayleigh-channel is closer to the practical situation. Based on the characteristics of atmospheric channel, which is modeled as logarithmic-normal distribution and K-distribution, we designed a special QC-LDPC code, and deduced the log-likelihood ratio (LLR). An irregular QC-LDPC code for fast coding, of which the rates are variable, is proposed in this paper. The proposed code achieves excellent performance of LDPC codes and can present the characteristics of high efficiency in low rate, stable in high rate and less number of iteration. The result of belief propagation (BP) decoding shows that the bit error rate (BER) obviously reduced as the Signal-to-Noise Ratio (SNR) increased. Therefore, the LDPC channel coding technology can effectively improve the performance of FSO. At the same time, the BER, after decoding reduces with the increase of SNR arbitrarily, and not having error limitation platform phenomenon with error rate slowing down.

  3. Associations between Family Communication Patterns, Sibling Closeness, and Adoptive Status

    Samek, Diana R.; Rueter, Martha A.

    2011-01-01

    Previous research has demonstrated the protective effect of family and sibling closeness on child adjustment, but fewer studies have investigated how closeness is promoted within families. Guided by Family Communication Patterns Theory, we tested the association between family communication and sibling emotional and behavioral closeness, and…

  4. Communication of Robot Status to Improve Human-Robot Collaboration

    National Aeronautics and Space Administration — Future space exploration will require humans and robots to collaborate to perform all the necessary tasks. Current robots mostly operate separately from humans due...

  5. Communication-Oriented Design Space Exploration for Reconfigurable Architectures

    Gogniat Guy

    2007-01-01

    Full Text Available Many academic works in computer engineering focus on reconfigurable architectures and associated tools. Fine-grain architectures, field programmable gate arrays (FPGAs, are the most well-known structures of reconfigurable hardware. Dedicated tools (generic or specific allow for the exploration of their design space to choose the best architecture characteristics and/or to explore the application characteristics. The aim is to increase the synergy between the application and the architecture in order to get the best performance. However, there is no generic tool to perform such an exploration for coarse-grain or heterogeneous-grain architectures, just a small number of very specific tools are able to explore a limited set of architectures. To address this major lack, in this paper we propose a new design space exploration approach adapted to fine- and coarse-grain granularities. Our approach combines algorithmic and architecture explorations. It relies on an automatic estimation tool which computes the communication hierarchical distribution and the architectural processing resources use rate for the architecture under exploration. Such an approach forwards the rapid definition of efficient reconfigurable architectures dedicated to one or several applications.

  6. The effect of relationship status on communicating emotions through touch

    Thompson, E. H.; Hampton, J. A.

    2011-01-01

    Research into emotional communication to date has largely focused on facial and vocal expressions. In contrast, recent studies by Hertenstein, Keltner, App, Bulleit, and Jaskolka (2006) and Hertenstein, Holmes, McCullough, and Keltner (2009) exploring nonverbal communication of emotion discovered that people could identify anger, disgust, fear, gratitude, happiness, love, sadness and sympathy from the experience of being touched on either the arm or body by a stranger, without seeing the touc...

  7. The Status of Ethics Scholarship in Speech Communication Journals from 1915 to 1985.

    Arnett, Ronald C.

    To examine the theoretical status of ethics scholarship and to explore the historical and present directions of ethics in human communication research, this paper reviews more than 100 articles drawn from the speech communication literature. Following a brief introduction that sets forth the criteria for article selection, the paper discusses…

  8. The effect of relationship status on communicating emotions through touch.

    Thompson, Erin H; Hampton, James A

    2011-02-01

    Research into emotional communication to date has largely focused on facial and vocal expressions. In contrast, recent studies by Hertenstein, Keltner, App, Bulleit, and Jaskolka (2006) and Hertenstein, Holmes, McCullough, and Keltner (2009) exploring nonverbal communication of emotion discovered that people could identify anger, disgust, fear, gratitude, happiness, love, sadness and sympathy from the experience of being touched on either the arm or body by a stranger, without seeing the touch. The study showed that strangers were unable to communicate the self-focused emotions embarrassment, envy and pride, or the universal emotion surprise. Literature relating to touch indicates that the interpretation of a tactile experience is significantly influenced by the relationship between the touchers (Coan, Schaefer, & Davidson, 2006). The present study compared the ability of romantic couples and strangers to communicate emotions solely via touch. Results showed that both strangers and romantic couples were able to communicate universal and prosocial emotions, whereas only romantic couples were able to communicate the self-focused emotions envy and pride. © 2010 Psychology Press, an imprint of the Taylor & Francis Group, an Informa business

  9. 2017 International Conference on Space Science and Communication

    2017-05-01

    Table of Content Preface 2017 International Conference on Space Science and CommunicationSpace Science for Sustainability” The present volume of the Journal of Physics: Conference Series represents contributions from participants of the 2017 International Conference on Space Science and Communication (IconSpace2017) held in Kuala Lumpur, Malaysia from May 3-5, 2017. The conference was organized by Space Science Centre (ANGKASA), Institute of Climate Change, Universiti Kebangsaan Malaysia (UKM) with a theme on “Space Science for Sustainability”. IconSpace2017 is the fifth series of conferences devoted to bringing researchers from around the world together to present and discuss their recent research results related to space science and communication, and also to provide an international platform for future research collaborations. This biennial international conference is an open forum where members in the field and others can meet in one place to discuss their current research findings. The technical program of this conference includes four keynote speakers, invited speakers, and the presentation of papers and poster. The track of the session includes Astrophysics and Astronomy, Atmospheric and Magnetospheric Sciences, Geoscience and Remote Sensing, Satellite and Communication Technology, and Interdisciplinary Space Science. Apart from the main conference, there will be a special talk on “Space Exploration & Updates” on 5 May 2017. More than 100 scientists and engineers from various academic, government, and industrial institutions in Europe, Asia, Australia, Africa, and the Americas attended the conference. The papers for this conference were selected after a rigorous review process. The papers were all evaluated by international and local reviewers and at least two reviewers were required to evaluate each paper. We should like to offer our thanks for the professionalism of the organizing committee, authors, reviewers, and volunteers deserve much

  10. 2017 International Conference on Space Science and Communication

    2017-01-01

    Table of Content Preface 2017 International Conference on Space Science and CommunicationSpace Science for Sustainability” The present volume of the Journal of Physics: Conference Series represents contributions from participants of the 2017 International Conference on Space Science and Communication (IconSpace2017) held in Kuala Lumpur, Malaysia from May 3-5, 2017. The conference was organized by Space Science Centre (ANGKASA), Institute of Climate Change, Universiti Kebangsaan Malaysia (UKM) with a theme on “Space Science for Sustainability”. IconSpace2017 is the fifth series of conferences devoted to bringing researchers from around the world together to present and discuss their recent research results related to space science and communication, and also to provide an international platform for future research collaborations. This biennial international conference is an open forum where members in the field and others can meet in one place to discuss their current research findings. The technical program of this conference includes four keynote speakers, invited speakers, and the presentation of papers and poster. The track of the session includes Astrophysics and Astronomy, Atmospheric and Magnetospheric Sciences, Geoscience and Remote Sensing, Satellite and Communication Technology, and Interdisciplinary Space Science. Apart from the main conference, there will be a special talk on “Space Exploration and Updates” on 5 May 2017. More than 100 scientists and engineers from various academic, government, and industrial institutions in Europe, Asia, Australia, Africa, and the Americas attended the conference. The papers for this conference were selected after a rigorous review process. The papers were all evaluated by international and local reviewers and at least two reviewers were required to evaluate each paper. We should like to offer our thanks for the professionalism of the organizing committee, authors, reviewers, and volunteers deserve much

  11. Programmable High-Rate Multi-Mission Receiver for Space Communications, Phase II

    National Aeronautics and Space Administration — Current and upcoming NASA space links require both highly reliable low-rate communications links supporting critical TT&C, ranging and voice services and highly...

  12. High-Efficiency, High-Power Laser Transmitter for Deep-Space Communication, Phase II

    National Aeronautics and Space Administration — There is demand for vastly improved deep space satellite communications links. As data rates dramatically increase due to new sensor technologies and the desire to...

  13. Highly Sensitive Photon Counting Detectors for Deep Space Optical Communications, Phase I

    National Aeronautics and Space Administration — A new type of a photon-counting photodetector is proposed to advance the state-of the-art in deep space optical communications technology. The proposed detector...

  14. Programmable High-Rate Multi-Mission Receiver for Space Communications, Phase I

    National Aeronautics and Space Administration — Current and upcoming NASA space links require both highly reliable low-rate communications links supporting critical TT&C, ranging and voice services and highly...

  15. Free-space laser communication technologies; Proceedings of the Meeting, Los Angeles, CA, Jan. 11, 12, 1988

    Koepf, Gerhard A.; Begley, David L.

    1988-01-01

    The present conference discusses topics in free-space laser communications, laser link characteristics, satellite laser communication systems, optoelectronic components for laser communications, and space laser subsystem technologies. Attention is given to Space Station-based deep-space communication experiments, the application of intersatellite links to operational satellite systems, high-power 0.87 micron channel substrate planar lasers for spaceborne communications, a ground experiment using a CO2 laser transceiver for free-space communications, studies of laser ranging to the TOPEX satellite, diffraction-limited tracking for space communications, and the compact implementation of a real-time, acoustooptic SAR processor.

  16. Quantum Limits of Space-to-Ground Optical Communications

    Hemmati, H.; Dolinar, S.

    2012-01-01

    For a pure loss channel, the ultimate capacity can be achieved with classical coherent states (i.e., ideal laser light): (1) Capacity-achieving receiver (measurement) is yet to be determined. (2) Heterodyne detection approaches the ultimate capacity at high mean photon numbers. (3) Photon-counting approaches the ultimate capacity at low mean photon numbers. A number of current technology limits drive the achievable performance of free-space communication links. Approaching fundamental limits in the bandwidth-limited regime: (1) Heterodyne detection with high-order coherent-state modulation approaches ultimate limits. SOA improvements to laser phase noise, adaptive optics systems for atmospheric transmission would help. (2) High-order intensity modulation and photon-counting can approach heterodyne detection within approximately a factor of 2. This may have advantages over coherent detection in the presence of turbulence. Approaching fundamental limits in the photon-limited regime (1) Low-duty cycle binary coherent-state modulation (OOK, PPM) approaches ultimate limits. SOA improvements to laser extinction ratio, receiver dark noise, jitter, and blocking would help. (2) In some link geometries (near field links) number-state transmission could improve over coherent-state transmission

  17. The roles of partner communication and relationship status in adolescent contraceptive use.

    Johnson, Abigail Z; Sieving, Renee E; Pettingell, Sandra L; McRee, Annie-Laurie

    2015-01-01

    Because of high rates of pregnancy and sexually transmitted infections among adolescents, factors influencing adolescents' contraceptive use require close examination. This study explores how different types of partner communication relate to contraceptive use among adolescent girls and whether these associations vary by relationship status. Cross-sectional, self-report data from 253 sexually active 13- to 17-year-old girls were used to examine associations between partner communication, relationship status, and contraceptive consistency. In a multivariate analysis, partner communication specific to contraceptive use (RR = 1.3, p communication on hormonal consistency was greater in steady partnerships than in casual partnerships. Findings suggest that clinicians should ask about the nature of adolescent girls' relationships with their sexual partners when encouraging contraceptive use. Early communication with partners about sexual topics should be stressed, especially among girls in steady relationships. Copyright © 2015 National Association of Pediatric Nurse Practitioners. Published by Elsevier Inc. All rights reserved.

  18. Modular space station, phase B extension. Information management advanced development. Volume 2: Communications terminal breadboard

    Gerber, C. R.

    1972-01-01

    The design and development of the communications terminal breadboard for the modular space station are discussed. The subjects presented are: (1) history of communications terminal breadboard, (2) requirements analysis, (3) technology goals in terminal design, and (4) communications terminal board integration tests.

  19. Current status and research of plant space mutation breeding

    Qiu Xinmian

    2011-01-01

    Plant space mutation breeding and discussed themechanism of plant space mutagenesis. The variations of organisms were induced by the comprehensive effects of high vacuum, microgravity,incense radiat ion and so on. The application of space mutation breeding and inheritance in specially good grmplasm material in China were well summarized. The prospects of space mutat ion breeding was described. The space mutagenesis will provided a new way for the future breeding. (author)

  20. Taking the Politics Out of Satellite and Space-Based Communications Protocols

    Ivancic, William D.

    2006-01-01

    After many years of studies, experimentation, and deployment, large amounts of misinformation and misconceptions remain regarding applicability of various communications protocols for use in satellite and space-based networks. This paper attempts to remove much of the politics, misconceptions, and misinformation that have plagued spacebased communications protocol development and deployment. This paper provides a common vocabulary for communications; a general discussion of the requirements for various communication environments; an evaluation of tradeoffs between circuit and packet-switching technologies, and the pros and cons of various link, network, transport, application, and security protocols. Included is the applicability of protocol enhancing proxies to NASA, Department of Defense (DOD), and commercial space communication systems.

  1. Application of spinal code for performance improvement in free-space optical communications

    Saiki, Naoya; Okamoto, Eiji; Takenaka, Hideki; Toyoshima, Morio

    2017-09-01

    In recent years, the demand for high-capacity communication has grown, and fiber-optic transmission is being used in wired communications to meet this demand. Similarly, free-space optics (FSO), which is an optical wireless communication technology that uses laser light, has attracted much attention and has been considered as a suitable alternative to satisfy this demand in wireless communications. Free-space optical communication uses a hundred THz frequency band and allows for high-speed and radio-regulation free transmission, which may provide a solution for the current shortage of radio frequency bands.

  2. Gravitational biology and space life sciences: Current status and ...

    Gravitational and space biology organizations and journals. American Institute of ... of Scientific Unions (now the International Council for. Science). COSPAR ... Greek Aerospace Medical Association & Space Research. (GASMA). Provides ...

  3. Inferring social status and rich club effects in enterprise communication networks.

    Dong, Yuxiao; Tang, Jie; Chawla, Nitesh V; Lou, Tiancheng; Yang, Yang; Wang, Bai

    2015-01-01

    Social status, defined as the relative rank or position that an individual holds in a social hierarchy, is known to be among the most important motivating forces in social behaviors. In this paper, we consider the notion of status from the perspective of a position or title held by a person in an enterprise. We study the intersection of social status and social networks in an enterprise. We study whether enterprise communication logs can help reveal how social interactions and individual status manifest themselves in social networks. To that end, we use two enterprise datasets with three communication channels--voice call, short message, and email--to demonstrate the social-behavioral differences among individuals with different status. We have several interesting findings and based on these findings we also develop a model to predict social status. On the individual level, high-status individuals are more likely to be spanned as structural holes by linking to people in parts of the enterprise networks that are otherwise not well connected to one another. On the community level, the principle of homophily, social balance and clique theory generally indicate a "rich club" maintained by high-status individuals, in the sense that this community is much more connected, balanced and dense. Our model can predict social status of individuals with 93% accuracy.

  4. Free Space Optical Communication in the Military Environment

    2014-09-01

    Charles River [6]. Even much earlier than Paul Revere’s ride, optical communication had developed into the semaphore or optical telegraph. The...forms of basic optical communication that are still commonplace today include semaphore flags and signal lamps utilized by navies around the world

  5. Space-Time Code Designs for Broadband Wireless Communications

    Xia, Xiang-Gen

    2005-01-01

    The goal of this research is to design new space AND time codes, such as complex orthogonal space AND time block codes with rate above 1/2 from complex orthogonal designs for QAM, PSK, and CPM signals...

  6. Unified Approach to Modeling and Simulation of Space Communication Networks and Systems

    Barritt, Brian; Bhasin, Kul; Eddy, Wesley; Matthews, Seth

    2010-01-01

    Network simulator software tools are often used to model the behaviors and interactions of applications, protocols, packets, and data links in terrestrial communication networks. Other software tools that model the physics, orbital dynamics, and RF characteristics of space systems have matured to allow for rapid, detailed analysis of space communication links. However, the absence of a unified toolset that integrates the two modeling approaches has encumbered the systems engineers tasked with the design, architecture, and analysis of complex space communication networks and systems. This paper presents the unified approach and describes the motivation, challenges, and our solution - the customization of the network simulator to integrate with astronautical analysis software tools for high-fidelity end-to-end simulation. Keywords space; communication; systems; networking; simulation; modeling; QualNet; STK; integration; space networks

  7. Iris Transponder-Communications and Navigation for Deep Space

    Duncan, Courtney B.; Smith, Amy E.; Aguirre, Fernando H.

    2014-01-01

    The Jet Propulsion Laboratory has developed the Iris CubeSat compatible deep space transponder for INSPIRE, the first CubeSat to deep space. Iris is 0.4 U, 0.4 kg, consumes 12.8 W, and interoperates with NASA's Deep Space Network (DSN) on X-Band frequencies (7.2 GHz uplink, 8.4 GHz downlink) for command, telemetry, and navigation. This talk discusses the Iris for INSPIRE, it's features and requirements; future developments and improvements underway; deep space and proximity operations applications for Iris; high rate earth orbit variants; and ground requirements, such as are implemented in the DSN, for deep space operations.

  8. A Study for Optimum Space-to-Ground Communication Concept for CubeSat and SmallSat Platforms

    National Aeronautics and Space Administration — This study is to explore the communication architecture for future space-to-ground CubeSat/SmallSat communication, through simulations, analyses, and identifying...

  9. Space Tweetup - from a participant to a Mars Tweetup organizer and a new format of space communication

    Haider, O.; Groemer, G.

    2014-01-01

    In September 2011, the European Space Agency (ESA) and the German Space Agency (DLR) organized the first European SpaceTweetup during the German Aerospace day. One of the authors was one of 60 participants at this SpaceTweetup in Cologne and experienced the concept of a Tweetup and the engagement of the participants from the inside view. Building upon this experience, the Austrian Space Forum (OeWF) organized the first Austrian MarsTweetup during the “Dachstein Mars analog simulation”. Between 27 Apr,2001 and May,2012, a five day Mars simulation was conducted by the Austrian Space Forum and international research partners at the Giant Ice caves at the Dachstein region in Austria. During this field test, the Aouda.X spacesuit simulator and selected geophysical and life-science related experiments were conducted. In this paper we outline the potential and limitations of social media and how to engage the general public to participate and communicate about space projects through their own experience. We show examples of material SpaceTweetup participants produced e.g. hundreds of tweets during the actual event, blog entries, photo galleries and how space communication can benefit from it. Our considerations on organizing a SpaceTweetup are complemented with a section on lessons learned.

  10. A Qualitative Examination of Physician Gender and Parental Status in Pediatric End-of-Life Communication.

    Bateman, Lori Brand; White, Marjorie Lee; Tofil, Nancy M; Clair, Jeffrey Michael; Needham, Belinda L

    2017-07-01

    In this study we utilized the framework of patient-centered communication to explore the influence of physician gender and physician parental status on (1) physician-parent communication and (2) care of pediatric patients at the end of life (EOL). The findings presented here emerged from a larger qualitative study that explored physician narratives surrounding pediatric EOL communication. The current study includes 17 pediatric critical care and pediatric emergency medicine physician participants who completed narrative interviews between March and October 2012 to discuss how their backgrounds influenced their approaches to pediatric EOL communication. Between April and June of 2013, participants completed a second round of narrative interviews to discuss topics generated out of the first round of interviews. We used grounded theory to inform the design and analysis of the study. Findings indicated that physician gender is related to pediatric EOL communication and care in two primary ways: (1) the level of physician emotional distress and (2) the way physicians perceive the influence of gender on communication. Additionally, parental status emerged as an important theme as it related to EOL decision-making and communication, emotional distress, and empathy. Although physicians reported experiencing more emotional distress related to interacting with patients at the EOL after they became parents, they also felt that they were better able to show empathy to parents of their patients.

  11. User Interfaces for Patient-Centered Communication of Health Status and Care Progress

    Wilcox-Patterson, Lauren

    2013-01-01

    The recent trend toward patients participating in their own healthcare has opened up numerous opportunities for computing research. This dissertation focuses on how technology can foster this participation, through user interfaces to effectively communicate personal health status and care progress to hospital patients. I first characterize the…

  12. The Status of the Business Communication Course at U.S. Colleges and Universities

    Russ, Travis L.

    2009-01-01

    This study examines the current status of the introductory business communication course at colleges and universities across the United States. Using data collected during the spring of 2008 from a national sample of 505 instructors, this study reveals a number of pedagogical and programmatic insights about (1) major course sponsors; (2) academic…

  13. Parenting Styles, Communication and Child/Adolescent Diets and Weight Status: Let's Talk about It

    Parletta, Natalie; Peters, Jacqueline; Owen, Amber; Tsiros, Margarita D.; Brennan, Leah

    2012-01-01

    Parenting styles have been associated with health-related behaviours in children and adolescents. We present a series of studies. Study 1 investigated parenting styles and parent-child communication styles as cross-sectional predictors of dietary patterns in children, and study 2 as cross-sectional predictors of weight status in adolescents. Data…

  14. Characterization of the Marine Atmosphere for Free-Space Optical Communication

    Thomas, Linda M. Wasiczko; Moore, Christopher I; Burris, Harris R; Suite, Michele; Stell, Mena; Murphy, James; Gilbreath, G. C; Rabinovich, William; Scharpf, William

    2006-01-01

    The Chesapeake Bay Detachment of the Naval Research Laboratory (NRL-CBD) provides an ideal environment for characterizing the effects of the marine atmosphere on free space optical communication links...

  15. Communications Relay and Human-Assisted Sample Return from the Deep Space Gateway

    Cichan, T.; Hopkins, J. B.; Bierhaus, B.; Murrow, D. W.

    2018-02-01

    The Deep Space Gateway can enable or enhance exploration of the lunar surface through two capabilities: 1. communications relay, opening up access to the lunar farside, and 2. sample return, enhancing the ability to return large sample masses.

  16. On the performance of free-space optical communication systems with multiuser diversity

    Yang, Liang; Gao, Xiqi; Alouini, Mohamed-Slim

    2014-01-01

    Free space optical (FSO) communication has become a cost-effective method to provide high data rates. However, the turbulence-induced fading limits its application to short range applications. To address this, we propose a multiuser diversity (MD

  17. Performance of Cat's Eye Modulating Retro-Reflectors for Free-Space Optical Communications

    Rabinovich, W. S; Goetz, P. G; Mahon, R; Swingen, L; Murphy, J; Gilbreath, G. C; Binari, S; Waluschka, E

    2004-01-01

    Modulating retro-reflectors (MRR) couple passive optical retro-reflectors with electro-optic modulators to allow free-space optical communication with a laser and pointing/acquisition/tracking system required on only one end of the link...

  18. Status of NASA's Stirling Space Power Converter Program

    Dudenhoefer, J.E.; Winter, J.M.

    1994-01-01

    An overview is presented of the NASA Lewis Research Center Free-Piston Stirling Space Power Converter Technology Program. This work is being conducted under NASA's Civil Space Technology Initiative. The goal of the CSTI High Capacity Power Element is to develop the technology base needed to meet the long duration, high capacity power requirements for future NASA space initiatives. Efforts are focused upon increasing system power output and system thermal and electric energy conversion efficiency at least fivefold over current SP-100 technology, and on achieving systems that are compatible with space nuclear reactors. This paper will discuss Stirling experience in Space Power Converters. Fabrication is nearly completed for the 1050 K Component Test Power Converter (CTPC); results of motoring tests of the cold end (525 K), are presented. The success of these and future designs is dependent upon supporting research and technology efforts including heat pipes, bearings, superalloy joining technologies, high efficiency alternators, life and reliability testing and predictive methodologies. This paper provides an update of progress in some of these technologies leading off with a discussion of free-piston Stirling experience in space

  19. Space Nuclear Power Public and Stakeholder Risk Communication

    Dawson, Sandra M.; Sklar, Maria

    2005-01-01

    The 1986 Challenger accident coupled with the Chernobyl nuclear reactor accident increased public concern about the safety of spacecraft using nuclear technology. While three nuclear powered spacecraft had been launched before 1986 with little public interest, future nuclear powered missions would see significantly more public concern and require NASA to increase its efforts to communicate mission risks to the public. In 1987 a separate risk communication area within the Launch Approval Planning Group of the Jet Propulsion Laboratory was created to address public concern about the health, environmental, and safety risks of NASA missions. The lessons learned from the risk communication strategies developed for the nuclear powered Galileo, Ulysses, and Cassini missions are reviewed in this paper and recommendations are given as to how these lessons can be applied to future NASA missions that may use nuclear power systems and other potentially controversial NASA missions.

  20. Economic benefits of the Space Station to commercial communication satellite operators

    Price, Kent M.; Dixson, John E.; Weyandt, Charles J.

    1987-01-01

    The economic and financial aspects of newly defined space-based activities, procedures, and operations (APOs) and associated satellite system designs are presented that have the potential to improve economic performance of future geostationary communications satellites. Launch insurance, launch costs, and the economics of APOs are examined. Retrieval missions and various Space Station scenarios are addressed. The potential benefits of the new APOs to the commercial communications satellite system operator are quantified.

  1. A review on channel models in free space optical communication systems

    Anbarasi, K.; Hemanth, C.; Sangeetha, R. G.

    2017-12-01

    Free Space Optical communication (FSO) is a wireless communication technology which uses light to transmit the data in free space. FSO has advantages like unlicensed spectrum and higher bandwidth. In this paper FSO system merits and demerits, challenges in FSO, and various channel models are discussed. To mitigate the turbulence in FSO the mitigation techniques like relaying, diversity schemes and adopting different modulation techniques used in different channels are discussed and its performance comparison is given.

  2. Integrated source and channel encoded digital communication system design study. [for space shuttles

    Huth, G. K.

    1976-01-01

    The results of several studies Space Shuttle communication system are summarized. These tasks can be divided into the following categories: (1) phase multiplexing for two- and three-channel data transmission, (2) effects of phase noise on the performance of coherent communication links, (3) analysis of command system performance, (4) error correcting code tradeoffs, (5) signal detection and angular search procedure for the shuttle Ku-band communication system, and (6) false lock performance of Costas loop receivers.

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

    1977-01-01

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

  4. The effect of jitter on the performance of space coherent optical communication system with Costas loop

    Li, Xin; Hong, Yifeng; Wang, Jinfang; Liu, Yang; Sun, Xun; Li, Mi

    2018-01-01

    Numerous communication techniques and optical devices successfully applied in space optical communication system indicates a good portability of it. With this good portability, typical coherent demodulation technique of Costas loop can be easily adopted in space optical communication system. As one of the components of pointing error, the effect of jitter plays an important role in the communication quality of such system. Here, we obtain the probability density functions (PDF) of different jitter degrees and explain their essential effect on the bit error rate (BER) space optical communication system. Also, under the effect of jitter, we research the bit error rate of space coherent optical communication system using Costas loop with different system parameters of transmission power, divergence angle, receiving diameter, avalanche photodiode (APD) gain, and phase deviation caused by Costas loop. Through a numerical simulation of this kind of communication system, we demonstrate the relationship between the BER and these system parameters, and some corresponding methods of system optimization are presented to enhance the communication quality.

  5. Evaluation of the Communication Between Arachnoid Cysts and Neighboring Cerebrospinal Fluid Spaces by T2W 3D-SPACE With Variant Flip-Angle Technique at 3 T.

    Algin, Oktay

    2018-05-21

    Phase-contrast cine magnetic resonance imaging (PC-MRI) is a widely used technique for determination of possible communication of arachnoid cysts (ACs). Three-dimensional (3D) sampling perfection with application-optimized contrasts using different flip-angle evolutions (3D-SPACE) technique is a relatively new method for 3D isotropic scanning of the entire cranium within a short time. In this research, the usage of the 3D-SPACE technique in differentiation of communicating or noncommunicating type ACs was evaluated. Thirty-five ACs in 34 patients were retrospectively examined. The 3D-SPACE, PC-MRI, and contrast material-enhanced cisternography (if present) images of the patients were analyzed. Each cyst was described according to cyst size/location, third ventricle diameter, Evans index, and presence of hydrocephalus. Communication was defined as absent (score 0), suspected (score 1), or present (score 2) on each sequence. Results of PC-MRI or cisternography (if available) examinations were used as criterion standard techniques to categorize all cysts as communicating or noncommunicating type. The results of 3D-SPACE were compared with criterion standard techniques. The comparisons between groups were performed using Mann-Whitney and Fisher exact tests. For demonstration of communication status of the cysts, criterion standard test results and 3D-SPACE findings were almost in perfect harmony (κ[95% confidence interval: 0.94]; P SPACE findings correlated with other final results at a rate of 97%. There is a positive correlation with third ventricular diameters and Evans index for all patients (r = 0.77, P SPACE technique is an easy, useful, and noninvasive alternative for the evaluation of morphology, topographical relationships, and communication status of ACs.

  6. Aragats space-environmental centre: status and SEP forecasting possibilities

    Chilingarian, A; Avakyan, K; Babayan, V; Bostanjyan, N; Chilingarian, S; Eganov, V; Hovhanissyan, A; Karapetyan, G; Gevorgyan, N; Gharagyozyan, G; Ghazaryan, S; Garyaka, A; Ivanov, V; Martirosian, H; Martirosov, R; Melkumyan, L; Sogoyan, H; Sokhoyan, S; Tserunyan, S; Vardanyan, A; Zazyan, M [Cosmic Ray Division, Yerevan Physics Institute, Alikhanyan Brothers 2, Yerevan 36 (Armenia); Yeremian, A [Stanford Linear Accelerator Center, Stanford, CA 94309 (United States)

    2003-05-01

    The Aragats Space Environment Center in Armenia provides real-time monitoring of cosmic particle fluxes. Neutron monitors operating at altitudes of 2000 m and 3200 m on Mt Aragats continuously gather data to detect possible abrupt enhancement of the count rates. Additional high precision detectors, measuring muon and electron fluxes, along with directional information have been put in operation on Mt Aragats in the summer of 2002. We plan to use this information to establish an early warning system against extreme solar energetic particle (SEP) events which pose danger to the satellite electronics and the space station crew. Solar ion and proton fluxes as measured by space-borne sensors on ACE and GOES satellites are used to derive expected arrival times of highest energy ions at 1 AU. The peaks in the time series detected by Aragats neutron monitors, coincided with these times, demonstrate the possibility of early detection of SEP events using the ground-based detectors.

  7. White space communication advances, developments and engineering challenges

    Johnson, David

    2015-01-01

    This monograph presents a collection of major developments leading toward the implementation of white space technology - an emerging wireless standard for using wireless spectrum in locations where it is unused by licensed users. Some of the key research areas in the field are covered. These include emerging standards, technical insights from early pilots and simulations, software defined radio platforms, geo-location spectrum databases and current white space spectrum usage in India and South Africa.

  8. Status of the organic Rankine cycle for space applications

    Bland, T. J.; Lacey, P. D.; Sorensen, G. L.

    The Organic Rankine Cycle (ORC) has been under continuous development and evaluation since the 1960s for both terrestrial and space power applications. Recent activities (Bland et al, 1987) have focused primarily on the Space Station's solar dynamic power system and Dynamic Isotope Power Systems (DIPS) applications. This paper addresses ORC-DIPS system level trade studies conducted during the past year and a half. Two companion papers (Bland and Pearson) present more detailed data on specific ORC-DIPS technology issues and testing conducted during the same period.

  9. Space Link Extension (SLE) Emulation for High-Throughput Network Communication

    Murawski, Robert W.; Tchorowski, Nicole; Golden, Bert

    2014-01-01

    As the data rate requirements for space communications increases, significant stress is placed not only on the wireless satellite communication links, but also on the ground networks which forward data from end-users to remote ground stations. These wide area network (WAN) connections add delay and jitter to the end-to-end satellite communication link, effects which can have significant impacts on the wireless communication link. It is imperative that any ground communication protocol can react to these effects such that the ground network does not become a bottleneck in the communication path to the satellite. In this paper, we present our SCENIC Emulation Lab testbed which was developed to test the CCSDS SLE protocol implementations proposed for use on future NASA communication networks. Our results show that in the presence of realistic levels of network delay, high-throughput SLE communication links can experience significant data rate throttling. Based on our observations, we present some insight into why this data throttling happens, and trace the probable issue back to non-optimal blocking communication which is sup-ported by the CCSDS SLE API recommended practices. These issues were presented as well to the SLE implementation developers which, based on our reports, developed a new release for SLE which we show fixes the SLE blocking issue and greatly improves the protocol throughput. In this paper, we also discuss future developments for our end-to-end emulation lab and how these improvements can be used to develop and test future space communication technologies.

  10. Space Communications and Data Systems Technologies for Next Generation Earth Science Measurements

    Bauer, Robert A.; Reinhart, Richard C.; Hilderman, Don R.; Paulsen, Phillip E.

    2003-01-01

    The next generation of Earth observing satellites and sensor networks will face challenges in supporting robust high rate communications links from the increasingly sophisticated onboard instruments. Emerging applications will need data rates forecast to be in the 100's to 1000's of Mbps. As mission designers seek smaller spacecraft, challenges exist in reducing the size and power requirements while increasing the capacity of the spacecraft's communications technologies. To meet these challenges, this work looks at three areas of selected space communications and data services technologies, specifically in the development of reflectarray antennas, demonstration of space Internet concepts, and measurement of atmospheric propagation effects on Ka-band signal transmitted from LEO.

  11. The ethics of communicative process: Discourse, otherness, and public space

    Ângela Cristina Salgueiro Marques

    2011-09-01

    Full Text Available The aim of this paper is to reflect on ethical-moral questions that are present in different dimensions of the contemporary communicative processes. At a first moment, I explain how Habermas defines the concept of discourse ethics witch is capable to allow the articulation and negotiation among the plurality of points of view and citizens in the current societies. In addition, I confer prominence to the role media play in the interconnection of different audiences and dispersed speeches in order to guarantee possibilities of renewal of collective debates in the public sphere. I therefore propose that an ethics of communication instead of be restrained to media devices and its operative dynamics, should consider their connections with citizens’ concrete practices and experiences.

  12. Space Communications Artificial Intelligence for Link Evaluation Terminal (SCAILET)

    Shahidi, Anoosh

    1991-01-01

    A software application to assis end-users of the Link Evaluation Terminal (LET) for satellite communication is being developed. This software application incorporates artificial intelligence (AI) techniques and will be deployed as an interface to LET. The high burst rate (HBR) LET provides 30 GHz transmitting/20 GHz receiving, 220/110 Mbps capability for wideband communications technology experiments with the Advanced Communications Technology Satellite (ACTS). The HBR LET and ACTS are being developed at the NASA Lewis Research Center. The HBR LET can monitor and evaluate the integrity of the HBR communications uplink and downlink to the ACTS satellite. The uplink HBR transmission is performed by bursting the bit-pattern as a modulated signal to the satellite. By comparing the transmitted bit pattern with the received bit pattern, HBR LET can determine the bit error rate BER) under various atmospheric conditions. An algorithm for power augmentation is applied to enhance the system's BER performance at reduced signal strength caused by adverse conditions. Programming scripts, defined by the design engineer, set up the HBR LET terminal by programming subsystem devices through IEEE488 interfaces. However, the scripts are difficult to use, require a steep learning curve, are cryptic, and are hard to maintain. The combination of the learning curve and the complexities involved with editing the script files may discourage end-users from utilizing the full capabilities of the HBR LET system. An intelligent assistant component of SCAILET that addresses critical end-user needs in the programming of the HBR LET system as anticipated by its developers is described. A close look is taken at the various steps involved in writing ECM software for a C&P, computer and at how the intelligent assistant improves the HBR LET system and enhances the end-user's ability to perform the experiments.

  13. User manual of the CATSS system (version 1.0) communication analysis tool for space station

    Tsang, C. S.; Su, Y. T.; Lindsey, W. C.

    1983-01-01

    The Communication Analysis Tool for the Space Station (CATSS) is a FORTRAN language software package capable of predicting the communications links performance for the Space Station (SS) communication and tracking (C & T) system. An interactive software package was currently developed to run on the DEC/VAX computers. The CATSS models and evaluates the various C & T links of the SS, which includes the modulation schemes such as Binary-Phase-Shift-Keying (BPSK), BPSK with Direct Sequence Spread Spectrum (PN/BPSK), and M-ary Frequency-Shift-Keying with Frequency Hopping (FH/MFSK). Optical Space Communication link is also included. CATSS is a C & T system engineering tool used to predict and analyze the system performance for different link environment. Identification of system weaknesses is achieved through evaluation of performance with varying system parameters. System tradeoff for different values of system parameters are made based on the performance prediction.

  14. Polarization tracking system for free-space optical communication, including quantum communication

    Nordholt, Jane Elizabeth; Newell, Raymond Thorson; Peterson, Charles Glen; Hughes, Richard John

    2018-01-09

    Quantum communication transmitters include beacon lasers that transmit a beacon optical signal in a predetermined state of polarization such as one of the states of polarization of a quantum communication basis. Changes in the beacon polarization are detected at a receiver, and a retarder is adjusted so that the states of polarization in a received quantum communication optical signal are matched to basis polarizations. The beacon and QC signals can be at different wavelengths so that the beacon does not interfere with detection and decoding of the QC optical signal.

  15. High and Mighty: Implicit Associations between Space and Social Status

    2011-10-10

    manipulated space at both small and large scales, from footwear to city planning, to convey social sta- tus (Hodder, 1987; Bourdieu , 1989; Margolies, 2003...posit that associ- ations between abstract concepts and physical percepts develop in response to everyday experiences (e.g., Hebb, 1949; Bourdieu ...The United States Capitol building was intentionally placed atop Jenkin’s Hill, described by the original architect Pierre Charles L’Enfant as a

  16. Face threatening acts in familiar communicational space in ...

    Such a constitution of face is referred to as a Face Threatening Act. This paper studies the face threatening acts in the interactional space among characters in Adichie's Purple Hibiscus and establishes how those acts aid or mar the illocutionary goals of participants. The study concludes that the 'face' is inseparable from ...

  17. DD-Amp for Deep Space Communications, Phase I

    National Aeronautics and Space Administration — AlGaN/GaN MMICs on SiC substrates will be utilized to achieve Power Added Efficiencies (PAE) in excess of 60%. These wide band-gap solid-state semiconductors will be...

  18. Space Communication Artificial Intelligence for Link Evaluation Terminal (SCAILET)

    Shahidi, Anoosh K.; Schlegelmilch, Richard F.; Petrik, Edward J.; Walters, Jerry L.

    1992-01-01

    A software application to assist end-users of the high burst rate (HBR) link evaluation terminal (LET) for satellite communications is being developed. The HBR LET system developed at NASA Lewis Research Center is an element of the Advanced Communications Technology Satellite (ACTS) Project. The HBR LET is divided into seven major subsystems, each with its own expert. Programming scripts, test procedures defined by design engineers, set up the HBR LET system. These programming scripts are cryptic, hard to maintain and require a steep learning curve. These scripts were developed by the system engineers who will not be available for the end-users of the system. To increase end-user productivity a friendly interface needs to be added to the system. One possible solution is to provide the user with adequate documentation to perform the needed tasks. With the complexity of this system the vast amount of documentation needed would be overwhelming and the information would be hard to retrieve. With limited resources, maintenance is another reason for not using this form of documentation. An advanced form of interaction is being explored using current computer techniques. This application, which incorporates a combination of multimedia and artificial intelligence (AI) techniques to provided end-users with an intelligent interface to the HBR LET system, is comprised of an intelligent assistant, intelligent tutoring, and hypermedia documentation. The intelligent assistant and tutoring systems address the critical programming needs of the end-user.

  19. Recent Successes and Future Plans for NASA's Space Communications and Navigation Testbed on the International Space Station

    Reinhart, Richard C.; Sankovic, John M.; Johnson, Sandra K.; Lux, James P.; Chelmins, David T.

    2014-01-01

    Flexible and extensible space communications architectures and technology are essential to enable future space exploration and science activities. NASA has championed the development of the Space Telecommunications Radio System (STRS) software defined radio (SDR) standard and the application of SDR technology to reduce the costs and risks of using SDRs for space missions, and has developed an on-orbit testbed to validate these capabilities. The Space Communications and Navigation (SCaN) Testbed (previously known as the Communications, Navigation, and Networking reConfigurable Testbed (CoNNeCT)) is advancing SDR, on-board networking, and navigation technologies by conducting space experiments aboard the International Space Station. During its first year(s) on-orbit, the SCaN Testbed has achieved considerable accomplishments to better understand SDRs and their applications. The SDR platforms and software waveforms on each SDR have over 1500 hours of operation and are performing as designed. The Ka-band SDR on the SCaN Testbed is NASAs first space Ka-band transceiver and is NASA's first Ka-band mission using the Space Network. This has provided exciting opportunities to operate at Ka-band and assist with on-orbit tests of NASA newest Tracking and Data Relay Satellites (TDRS). During its first year, SCaN Testbed completed its first on-orbit SDR reconfigurations. SDR reconfigurations occur when implementing new waveforms on an SDR. SDR reconfigurations allow a radio to change minor parameters, such as data rate, or complete functionality. New waveforms which provide new capability and are reusable across different missions provide long term value for reconfigurable platforms such as SDRs. The STRS Standard provides guidelines for new waveform development by third parties. Waveform development by organizations other than the platform provider offers NASA the ability to develop waveforms itself and reduce its dependence and costs on the platform developer. Each of these

  20. The Effects of Space Environment on Wireless Communication Devices' Performance

    Landon, Hillyard; Dennison, JR

    2012-01-01

    This project evaluates the effects of the space environment on small radio hardware devices called Bluetooth (a proprietary open wireless technology standard for exchanging data over short distances) chips (hoovers). When electronics are exposed to the harsh environment outside the Earth's atmosphere, they sometimes do not perform as expected. The USU Getaway Away Special (GAS) team is now in the design stages of launching a CubeSat (a 10 cm cubed autonomous satellite to fly in Low Earth Orbi...

  1. Vessel noise cuts down communication space for vocalizing fish and marine mammals.

    Putland, Rosalyn L; Merchant, Nathan D; Farcas, Adrian; Radford, Craig A

    2018-04-01

    Anthropogenic noise across the world's oceans threatens the ability of vocalizing marine species to communicate. Some species vocalize at key life stages or whilst foraging, and disruption to the acoustic habitat at these times could lead to adverse consequences at the population level. To investigate the risk of these impacts, we investigated the effect of vessel noise on the communication space of the Bryde's whale Balaenoptera edeni, an endangered species which vocalizes at low frequencies, and bigeye Pempheris adspersa, a nocturnal fish species which uses contact calls to maintain group cohesion while foraging. By combining long-term acoustic monitoring data with AIS vessel-tracking data and acoustic propagation modelling, the impact of vessel noise on their communication space was determined. Routine vessel passages cut down communication space by up to 61.5% for bigeyes and 87.4% for Bryde's whales. This influence of vessel noise on communication space exceeded natural variability for between 3.9 and 18.9% of the monitoring period. Additionally, during the closest point of approach of a large commercial vessel, communication space of both species was reduced by a maximum of 99% compared to the ambient soundscape. These results suggest that vessel noise reduces communication space beyond the evolutionary context of these species and may have chronic effects on these populations. To combat this risk, we propose the application or extension of ship speed restrictions in ecologically significant areas, since our results indicate a reduction in sound source levels for vessels transiting at lower speeds. © 2017 John Wiley & Sons Ltd.

  2. Morphological and Hemodynamic Discriminators for Rupture Status in Posterior Communicating Artery Aneurysms

    Lv, Nan; Wang, Chi; Karmonik, Christof; Fang, Yibin; Xu, Jinyu; Yu, Ying; Cao, Wei; Liu, Jianmin; Huang, Qinghai

    2016-01-01

    Background and Purpose The conflicting findings of previous morphological and hemodynamic studies on intracranial aneurysm rupture may be caused by the relatively small sample sizes and the variation in location of the patient-specific aneurysm models. We aimed to determine the discriminators for aneurysm rupture status by focusing on only posterior communicating artery (PCoA) aneurysms. Materials and Methods In 129 PCoA aneurysms (85 ruptured, 44 unruptured), clinical, morphological and hemo...

  3. A network society communicative model for optimizing the Refugee Status Determination (RSD procedures

    Andrea Pacheco Pacífico

    2013-01-01

    Full Text Available This article recommends a new way to improve Refugee Status Determination (RSD procedures by proposing a network society communicative model based on active involvement and dialogue among all implementing partners. This model, named after proposals from Castells, Habermas, Apel, Chimni, and Betts, would be mediated by the United Nations High Commissioner for Refugees (UNHCR, whose role would be modeled after that of the International Committee of the Red Cross (ICRC practice.

  4. XML: James Webb Space Telescope Database Issues, Lessons, and Status

    Detter, Ryan; Mooney, Michael; Fatig, Curtis

    2003-01-01

    This paper will present the current concept using extensible Markup Language (XML) as the underlying structure for the James Webb Space Telescope (JWST) database. The purpose of using XML is to provide a JWST database, independent of any portion of the ground system, yet still compatible with the various systems using a variety of different structures. The testing of the JWST Flight Software (FSW) started in 2002, yet the launch is scheduled for 2011 with a planned 5-year mission and a 5-year follow on option. The initial database and ground system elements, including the commands, telemetry, and ground system tools will be used for 19 years, plus post mission activities. During the Integration and Test (I&T) phases of the JWST development, 24 distinct laboratories, each geographically dispersed, will have local database tools with an XML database. Each of these laboratories database tools will be used for the exporting and importing of data both locally and to a central database system, inputting data to the database certification process, and providing various reports. A centralized certified database repository will be maintained by the Space Telescope Science Institute (STScI), in Baltimore, Maryland, USA. One of the challenges for the database is to be flexible enough to allow for the upgrade, addition or changing of individual items without effecting the entire ground system. Also, using XML should allow for the altering of the import and export formats needed by the various elements, tracking the verification/validation of each database item, allow many organizations to provide database inputs, and the merging of the many existing database processes into one central database structure throughout the JWST program. Many National Aeronautics and Space Administration (NASA) projects have attempted to take advantage of open source and commercial technology. Often this causes a greater reliance on the use of Commercial-Off-The-Shelf (COTS), which is often limiting

  5. Methods and Devices for Space Optical Communications Using Laser Beams

    Goorjian, Peter M. (Inventor)

    2018-01-01

    Light is used to communicate between objects separated by a large distance. Light beams are received in a telescopic lens assembly positioned in front of a cat's-eye lens. The light can thereby be received at various angles to be output by the cat's-eye lens to a focal plane of the cat's-eye lens, the position of the light beams upon the focal plane corresponding to the angle of the beam received. Lasers and photodetectors are distributed along this focal plane. A processor receives signals from the photodetectors, and selectively signal lasers positioned proximate the photodetectors detecting light, in order to transmit light encoding data through the cat's-eye lens and also through a telescopic lens back in the direction of the received light beams, which direction corresponds to a location upon the focal plane of the transmitting lasers.

  6. Integrating Space Communication Network Capabilities via Web Portal Technologies

    Johnston, Mark D.; Lee, Carlyn-Ann; Lau, Chi-Wung; Cheung, Kar-Ming; Levesque, Michael; Carruth, Butch; Coffman, Adam; Wallace, Mike

    2014-01-01

    We have developed a service portal prototype as part of an investigation into the feasibility of using Java portlet technology as a means of providing integrated access to NASA communications network services. Portal servers provide an attractive platform for this role due to the various built-in collaboration applications they can provide, combined with the possibility to develop custom inter-operating portlets to extent their functionality while preserving common presentation and behavior. This paper describes various options for integration of network services related to planning and scheduling, and results based on use of a popular open-source portal framework. Plans are underway to develop an operational SCaN Service Portal, building on the experiences reported here.

  7. Status report on nuclear reactors for space electric power

    Buden, D.

    1978-01-01

    The Los Alamos Scientific Laboratory is studying reactor power plants for space applications in the late 1980s and 1990s. The study is concentrating on high-temperature, compact, fast reactors that can be coupled with various radiation shielding systems and thermoelectric, dynamic, or thermionic electric power conversion systems, depending on the mission. Increased questions have been raised about safety since the COSMOS 954 incident. High orbits (above 400 to 500 nautical miles) have sufficient lifetimes to allow radioactive elements to decay to safe levels. The major proposed applications for satellites with reactors in Earth orbit are in geosynchronous orbit (19,400 nautical miles). In missions at geosynchronous orbit where orbital lifetimes are practically indefinite, the safety considerations are negligible. The potential missions, why reactors are being considered as a prime power candidate, reactor features, and safety considerations are discussed

  8. Programmatic overview of GMES Space Component and implementation status

    Aschbacher, Josef; Milagro, Maria Pilar

    2010-05-01

    GMES, the Global Monitoring for Environment and Security initiative, is a programme to provide the most comprehensive understanding of the state of land, air and water. Created in 1998 as an independent joint initiative of the European Commission (EC) and the European Space Agency (ESA), GMES will combine information from the world's biggest fleet of satellites and from thousands of atmospheric and Earth based sensors across the world in order to provide joined-up, timely, reliable and easily accessible information in domains such as natural disaster planning and response, the environment, agriculture, land use, climate change and security. GMES is made up of an In-situ Component, a Services Component and a Space Component. ESA is responsible for coordinating the Space Component which is composed of dedicated satellite missions, called Sentinels, and so called Contributing Missions, owned and operated by national agencies or commercial entities of ESA/EU Member States, EUMETSAT or other third parties. It also comprises the associated Ground Segment infrastructure necessary to access, process and disseminate the data from the multitude of missions contributing to GMES. ESA is also responsible for the development and procurement of the dedicated Sentinel satellites. Lastly, ESA will act as interim operator for Sentinel missions -1, -2 and land part of Sentinel-3 while EUMETSAT will operate the ocean part of Sentinel-3 as well as the S-4/-5 instruments which are flying on-board EUMETSAT's MTG and post-EPS respectively. The Sentinels will be the first series of dedicated operational satellites to meet the Earth observation needs of GMES users concerning atmosphere, ocean and land monitoring as well as emergency response and security. The Sentinel-1 constellation is a pair of synthetic aperture radar (SAR) imaging satellites. It ensures continuity of C-band SAR data and builds upon heritage and experience with the ERS and Envisat satellites. Sentinel-1 satellites will

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

    Tobiska, W. Kent

    2008-01-01

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

  10. Current status and future of space development; Uchu kaihatsu no genjo to shorai

    Matokawa, Y. [Institute of the Space and Astronautical Science, Tokyo (Japan)

    1998-05-01

    Space development has an aspect of contributing to livelihoods. Various types of satellites, such as those for weather forecasting, TV broadcasting, international communication (telephone and internet systems), and GPS-aided car navigation, have been already launched. Space science of the 20th century roughly tells the history of some 15 billion years from the big bang to birth of mankind as a spectacular story. The international space station, construction of which is to be started in 1998, should drastically enlarge man`s experiences in the universe. The space activity plans for the future draw various dreams, such as spaceplane, lunar base, solar generator satellite, Mars base, space colony, skyhook, and so on. Dreams of mankind have been eventually realized in the past history. It is time to deliberately assess what are meant by the space development of the 20th century, and to review ideal directions of the space development for the next 100 or 1000 years. 6 figs.

  11. Origins Space Telescope Concept 2: Trades, Decisions, and Study Status

    Leisawitz, David; DiPirro, Michael; Carter, Ruth; Origins Space Telescope Decadal Mission Concept Study Team

    2018-01-01

    The Origins Space Telescope (OST) will trace the history of our cosmic origins from the time dust and heavy elements began to alter the astrophysical processes that shaped galaxies and enabled planets to form, culminating at least once in the development of a life-bearing planet. But how did the universe evolve in response to its changing ingredients, and how common are planets that support life? The OST, an advancing concept for the Far-Infrared Surveyor mission described in the NASA Astrophysics roadmap, is being designed to answer these questions. As envisaged in the Roadmap, Enduring Quests/Daring Visions, OST will offer sensitivity and spectroscopic capabilities that vastly exceed those found in any preceding far-IR observatory. The spectral range of OST was extended down to 6 microns to allow measurements of key biomarkers in transiting exoplanet spectra. Thus, OST is a mid- and far-IR mission. OST Concept 2 will inform the Science and Technology Definition Team’s understanding of the “solution space,” enabling a recommendation to the 2020 Decadal Survey which, while not fully optimized, will be scientifically compelling, executable, and intended to maximize the science return per dollar. OST Concept 1, described in a companion paper, would satisfy virtually all of the STDT’s science objectives in under 5 years. Concept 2 is intentionally less ambitious than Concept 1, but it still includes a 4 K telescope, enabling exquisitely sensitive far-IR measurements. This paper will summarize the architecture options considered for OST Concept 2 and describe the factors that led to the chosen design concept. Lessons from the Concept 1 study influenced our choices. We report progress on the Concept 2 study to date.

  12. Reliability issues of free-space communications systems and networks

    Willebrand, Heinz A.

    2003-04-01

    Free space optics (FSO) is a high-speed point-to-point connectivity solution traditionally used in the enterprise campus networking market for building-to-building LAN connectivity. However, more recently some wire line and wireless carriers started to deploy FSO systems in their networks. The requirements on FSO system reliability, meaing both system availability and component reliability, are far more stringent in the carrier market when compared to the requirements in the enterprise market segment. This paper tries to outline some of the aspects that are important to ensure carrier class system reliability.

  13. Mixed Integer Programming and Heuristic Scheduling for Space Communication Networks

    Lee, Charles H.; Cheung, Kar-Ming

    2012-01-01

    In this paper, we propose to solve the constrained optimization problem in two phases. The first phase uses heuristic methods such as the ant colony method, particle swarming optimization, and genetic algorithm to seek a near optimal solution among a list of feasible initial populations. The final optimal solution can be found by using the solution of the first phase as the initial condition to the SQP algorithm. We demonstrate the above problem formulation and optimization schemes with a large-scale network that includes the DSN ground stations and a number of spacecraft of deep space missions.

  14. Near Earth Architectural Options for a Future Deep Space Optical Communications Network

    Edwards, B. L.; Liebrecht, P. E.; Fitzgerald, R. J.

    2004-01-01

    In the near future the National Aeronautics and Space Administration anticipates a significant increase in demand for long-haul communications services from deep space to Earth. Distances will range from 0.1 to 40 AU, with data rate requirements in the 1's to 1000's of Mbits/second. The near term demand is driven by NASA's Space Science Enterprise which wishes to deploy more capable instruments onboard spacecraft and increase the number of deep space missions. The long term demand is driven by missions with extreme communications challenges such as very high data rates from the outer planets, supporting sub-surface exploration, or supporting NASA's Human Exploration and Development of Space Enterprise beyond Earth orbit. Laser communications is a revolutionary communications technology that will dramatically increase NASA's ability to transmit information across the solar system. Lasercom sends information using beams of light and optical elements, such as telescopes and optical amplifiers, rather than RF signals, amplifiers, and antennas. This paper provides an overview of different network options at Earth to meet NASA's deep space lasercom requirements. It is based mainly on work done for the Mars Laser Communications Demonstration Project, a joint project between NASA's Goddard Space Flight Center (GSFC), the Jet Propulsion Laboratory, California Institute of Technology (JPL), and the Massachusetts Institute of Technology Lincoln Laboratory (MIT/LL). It reports preliminary conclusions from the Mars Lasercom Study conducted at MIT/LL and on additional work done for the Tracking and Data Relay Satellite System Continuation Study at GSFC. A lasercom flight terminal will be flown on the Mars Telesat Orbiter (MTO) to be launched by NASA in 2009, and will be the first high rate deep space demonstration of this revolutionary technology.

  15. Communicating with the public: space of nuclear technology

    Maffei, Patricia Martinez; Aquino, Afonso Rodrigues; Gordon, Ana Maria Pinho Leite; Oliveira, Rosana Lagua de; Padua, Rafael Vicente de; Vieira, Martha Marques Ferreira; Vicente, Roberto, E-mail: pmaffei@ipen.br, E-mail: araquino@usp.br, E-mail: amgordon@ipen.br, E-mail: rloliveira@ipen.br, E-mail: rpadua@ipen.br, E-mail: mmvieira@ipen.br, E-mail: rvicente@ipen.br [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil)

    2011-07-01

    For two decades the Nuclear and Energy Research Institute (IPEN) has been developing activities for popularization of its R and D activities in the nuclear field. Some of the initiatives already undertaken by IPEN are lectures at schools, guided visits to IPEN facilities, printed informative material, FAQ page in the Web, and displays in annual meetings and technology fairs highlighting its achievements. In order to consolidate these initiatives, IPEN is planning to have a permanent Space of Nuclear Technology (SNT), aiming at introducing students, teachers and the general public to the current applications of nuclear technology in medicine, industry, research, electric power generation, etc. It is intended as an open room to the public and will have a permanent exhibit with historical, scientific, technical and cultural developments of nuclear technology and will also feature temporary exhibitions about specific themes. The space will display scientific material in different forms to allow conducting experiments to demonstrate some of the concepts associated with the properties of nuclear energy, hands-on programs and activities that can be customized to the students' grade level and curriculum. (author)

  16. Communicating with the public: space of nuclear technology

    Maffei, Patricia Martinez; Aquino, Afonso Rodrigues; Gordon, Ana Maria Pinho Leite; Oliveira, Rosana Lagua de; Padua, Rafael Vicente de; Vieira, Martha Marques Ferreira; Vicente, Roberto

    2011-01-01

    For two decades the Nuclear and Energy Research Institute (IPEN) has been developing activities for popularization of its R and D activities in the nuclear field. Some of the initiatives already undertaken by IPEN are lectures at schools, guided visits to IPEN facilities, printed informative material, FAQ page in the Web, and displays in annual meetings and technology fairs highlighting its achievements. In order to consolidate these initiatives, IPEN is planning to have a permanent Space of Nuclear Technology (SNT), aiming at introducing students, teachers and the general public to the current applications of nuclear technology in medicine, industry, research, electric power generation, etc. It is intended as an open room to the public and will have a permanent exhibit with historical, scientific, technical and cultural developments of nuclear technology and will also feature temporary exhibitions about specific themes. The space will display scientific material in different forms to allow conducting experiments to demonstrate some of the concepts associated with the properties of nuclear energy, hands-on programs and activities that can be customized to the students' grade level and curriculum. (author)

  17. TRENDS IN THE DEVELOPMENT OF MARKETING COMMUNICATIONS IN THE GLOBAL INTERACTIVE SPACE

    N. Kochkina

    2014-09-01

    Full Text Available The article identifies trends in the development of marketing communications in the global interactive space by analyzing the factors of their functioning and researching motivation of viral audience. It is revealed the prevalence of interactive technologies in today's information space and the growth dynamics of interactive advertising market. It is proved that favorable conditions for marketing communications' functioning forms the basis for the development of viral advertising as an effective communication tool for untraditional impact on potential customers. The popularity of social networks as a major source of viral messages is determined. The motivation of YouTube audience, which provides a resonant video viewing and retransmission, is investigated. Gender and age differences that stipulate communication affect on consumers are identified. Cyclic social consciousness is observed that demands further research of viral audience, including constructing scenarios of viral behavior.

  18. Overlapping and permeability: Research on the pattern hierarchy of communication space and design strategy based on environmental behavior

    Leilei, Sun; Liang, Zhang; Bing, Chen; Hong, Xi

    2017-11-01

    This thesis is to analyze the basic pattern hierarchy of communication space by using the theory of environmental psychology and behavior combined with relevant principles in architecture, to evaluate the design and improvement of communication space in specific meaning, and to bring new observation ideas and innovation in design methods to the system of space, environment and behavior.

  19. Status of the International Space Station Waste and Hygiene Compartment

    Walker, Stephanie; Zahner, Christopher

    2010-01-01

    The Waste and Hygiene Compartment (WHC) serves as the primary system for removal and containment of metabolic waste and hygiene activities on board the United States segment of the International Space Station (ISS). The WHC was launched on ULF 2 and is currently in the U.S. Laboratory and is integrated into the Water Recovery System (WRS) where pretreated urine is processed by the Urine Processor Assembly (UPA). The waste collection part of the WHC system is derived from the Service Module system and was provided by RSC-Energia along with additional hardware to allow for urine delivery to the UPA. The System has been integrated in an ISS standard equipment rack structure for use on the U.S. segment of the ISS. The system has experienced several events of interest during the deployment, checkout, and operation of the system during its first year of use and these will be covered in this paper. Design and on-orbit performance will also be discussed.

  20. NASA space communications R and D (Research and Development): Issues, derived benefits, and future directions

    1989-02-01

    Space communication is making immense strides since ECHO was launched in 1962. It was a simple passive reflector of signals that demonstrated the concept. Today, satellites incorporating transponders, sophisticated high-gain antennas, and stabilization systems provide voice, video, and data communications to millions of people nationally and worldwide. Applications of emerging technology, typified by NASA's Advanced Communications Technology Satellite (ACTS) to be launched in 1992, will use newer portions of the frequency spectrum (the Ka-band at 30/20 GHz), along with antennas and signal-processing that could open yet new markets and services. Government programs, directly or indirectly, are responsible for many space communications accomplishments. They are sponsored and funded in part by NASA and the U.S. Department of Defense since the early 1950s. The industry is growing rapidly and is achieving international preeminence under joint private and government sponsorship. Now, however, the U.S. space communications industry - satellite manufacturers and users, launch services providers, and communications services companies - are being forced to adapt to a different environment. International competition is growing, and terrestrial technologies such as fiber optics are claiming markets until recently dominated by satellites. At the same time, advancing technology is opening up opportunities for new applications and new markets in space exploration, for defense, and for commercial applications of several types. Space communications research, development, and applications (RD and A) programs need to adjust to these realities, be better coordinated and more efficient, and be more closely attuned to commercial markets. The programs must take advantage of RD and A results in other agencies - and in other nations.

  1. Obstacle evasion in free-space optical communications utilizing Airy beams

    Zhu, Guoxuan; Wen, Yuanhui; Wu, Xiong; Chen, Yujie; Liu, Jie; Yu, Siyuan

    2018-03-01

    A high speed free-space optical communication system capable of self-bending signal transmission around line-of-sight obstacles is proposed and demonstrated. Airy beams are generated and controlled to achieve different propagating trajectories, and the signal transmission characteristics of these beams around the obstacle are investigated. Our results confirm that, by optimising their ballistic trajectories, Airy beams are able to bypass obstacles with more signal energy and thus improve the communication performance compared with normal Gaussian beams.

  2. Preface to the special issue on ;Optical Communications Exploiting the Space Domain;

    Wang, Jian; Yu, Siyuan; Li, Guifang

    2018-02-01

    The demand for high capacity optical communications will continue to be driven by the exponential growth of global internet traffic. Optical communications are about the exploitation of different physical dimensions of light waves, including complex amplitude, frequency (or wavelength), time, polarization, etc. Conventional techniques such as wavelength-division multiplexing (WDM), time-division multiplexing (TDM) and polarization-division multiplexing (PDM) have almost reached their scalability limits. Space domain is the only known physical dimension left and space-division multiplexing (SDM) seems the only option to further scale the transmission capacity and spectral efficiency of optical communications. In recent years, few-mode fiber (FMF), multi-mode fiber (MMF), multi-core fiber (MCF) and few-mode multi-core fiber (FM-MCF) have been widely explored as promising candidates for fiber-based SDM. The challenges for SDM include efficient (de)multiplexer, amplifiers, and multiple-input multiple-output (MIMO) digital signal processing (DSP) techniques. Photonic integration will also be a key technology to SDM. Meanwhile, free-space and underwater optical communications have also exploited the space domain to increase the transmission capacity and spectral efficiency. The challenges include long-distance transmission limited by propagation loss, divergence, scattering and turbulence. Very recently, helically phased light beams carrying orbital angular momentum (OAM) have also seen potential applications both in free-space, underwater and fiber-based optical communications. Actually, different mode bases such as linearly polarized (LP) modes and OAM modes can be employed for SDM. Additionally, SDM could be used in chip-scale photonic interconnects and data center optical interconnects. Quantum processing exploiting the space domain is of great interest. The information capacity limit and physical layer security in SDM optical communications systems are important

  3. Green Monopropellant Status at Marshall Space Flight Center

    Burnside, Christopher G.; Pierce, Charles W.; Pedersen, Kevin W.

    2016-01-01

    NASA Marshall Space Flight Center is continuing investigations into the use of green monopropellants as a replacement for hydrazine in spacecraft propulsion systems. Work to date has been to push technology development through multiple activities designed to understand the capabilities of these technologies. Future work will begin to transition to mission pull as these technologies are mature while still keeping a solid goal of pushing technology development as opportunities become available. The AF-M315E activities began with hot-fire demonstration testing of a 1N monopropellant thruster in FY 14 and FY15. Following successful completion of the preliminary campaign, changes to the test stand to accommodate propellant conditioning capability and better control of propellant operations was incorporated to make testing more streamlined. The goal is to conduct hot-fire testing with warm and cold propellants using the existing feed system and original thruster design. Following the 1N testing, a NASA owned 100 mN thruster will be hot-fire tested in the same facility to show feasibility of scaling to smaller thrusters for cubesat applications. The end goal is to conduct a hot-fire test of an integrated cubesat propulsion system using an SLM printed propellant tank, an MSFC designed propulsion system electronic controller and the 100 mN thruster. In addition to the AF-M315E testing, MSFC is pursuing hot-fire testing with LMP-103S. Following our successful hot-fire testing of the 22N thruster in April 2015, a test campaign was proposed for a 440N LMP-103S thruster with Orbital ATK and Plasma Processes. This activity was funded through the Space Technology Mission Directorate (STMD) ACO funding call in the last quarter of CY15. Under the same funding source a test activity with Busek and Glenn Research Center for testing of 5N AF-M315E thrusters was proposed and awarded. Both activities are in-work with expected completion of hot-fire testing by the end of FY17. MSFC is

  4. The Synthesis Method of Automated System of Operational Planning in Low-Space Communication System Messaging

    Serhii Kovbasiuk

    2017-04-01

    Full Text Available One of the reasons for the decrease of efficiency in low-speed communication systems, satellite communication, which are based on nanoplatform is a high degree of operational planning centralisation. To overcome this problem the method which carries out the distribution of tasks of communications operational planning minimizing the exchange of information between spatially remote sites, and takes into account the computing performance of software and hardware was developed. The technique is based on the use of methods of structural and parametric synthesis, simulation and statistical analysis of the results. Its use allows to obtain the optimal structure of the automated system of operational planning in low-space communication system messaging evaluation of efficiency in terms of fixed communication of information load.

  5. The Organizational-Methodical Mechanism for Influencing the Status of Internal Communications of Enterprise

    Saher Liudmyla Yu.

    2017-10-01

    Full Text Available The article explores the essence of the organizational-economic mechanism, defines the main constituent elements and proposes a structural-logical relations diagram of the mechanism for management of the internal communication processes of enterprises. The basic principles of management are allocated, their hierarchy is provided from a position of grade of influence on the process of internal communications management. A list of management methods within the proposed management mechanism (economic, social-psychological, organizational is described. It has been determined that the application of one group of methods in the process of managing the internal communications of enterprise without the use of others cannot have a lasting positive effect, because the management process requires an integrated and systemic approach. The author provides a sequence of phases of the internal communications management based on the process of diagnosing the status of the internal communication processes of enterprise and the formation of strategic directions of activity along with the managerial decision-making on its basis.

  6. Overview of some projects of SNPS for global space communication

    Ivanov, E.; Ghitajkin, V.; Ionkin, V.; Dubinin, A.; Pyshko, A.

    2000-01-01

    Modem concepts of the application of power technology in space believe in using an onboard source of energy for maintenance of self-transportation of the vehicle into working geosynchronous orbit (GEO). This can result in reduction of the cost of all installation and the number of rocket starts. There we present several conceptual projects of nuclear power installations. Power units developed with, IPPE's participation are intended for long term supply of electricity to the vehicle in GEO and to maintain self-transportation of capabilities. Considered units include a tiny, fast neutron nuclear reactor, radiation shield, control system, cooling system (radiator) and power conversion system. Additionally, they must also include a rocket engine to maintain the dual-mode regime. This may be an electric-stationary ion jet (with Xe as working body) and a thermal engine such as hybrid or NRE. There are three more prospective systems as follows: (a) gas cooled nuclear reactor with hybrid thermal engine and machine power converter; (b) nuclear reactor cooled by liquid metal and with a thermoelectric power generating system; (c) nuclear reactor with Li cooling and a thermionic and thermoelectric power generator on board. All considered schemes have two thermal circuits and use thermal pipes in the radiator. Two final concepts are based on a Xe electric jet; these differ from first concept by having a lower working body mass but a longer transportation period from basic orbit into GEO. (authors)

  7. Morphological and Hemodynamic Discriminators for Rupture Status in Posterior Communicating Artery Aneurysms.

    Nan Lv

    Full Text Available The conflicting findings of previous morphological and hemodynamic studies on intracranial aneurysm rupture may be caused by the relatively small sample sizes and the variation in location of the patient-specific aneurysm models. We aimed to determine the discriminators for aneurysm rupture status by focusing on only posterior communicating artery (PCoA aneurysms.In 129 PCoA aneurysms (85 ruptured, 44 unruptured, clinical, morphological and hemodynamic characteristics were compared between the ruptured and unruptured cases. Multivariate logistic regression analysis was performed to determine the discriminators for rupture status of PCoA aneurysms.While univariate analyses showed that the size of aneurysm dome, aspect ratio (AR, size ratio (SR, dome-to-neck ratio (DN, inflow angle (IA, normalized wall shear stress (NWSS and percentage of low wall shear stress area (LSA were significantly associated with PCoA aneurysm rupture status. With multivariate analyses, significance was only retained for higher IA (OR = 1.539, p < 0.001 and LSA (OR = 1.393, p = 0.041.Hemodynamics and morphology were related to rupture status of intracranial aneurysms. Higher IA and LSA were identified as discriminators for rupture status of PCoA aneurysms.

  8. Making media work in space: an interdisciplinary perspective on media and communication requirements for current and future space communities

    Babidge, S.; Cokley, J.; Gordon, F.; Louw, E.

    2005-10-01

    As humans expand into space communities will form. These have already begun to form in small ways, such as long-duration missions on the International Space Station and the space shuttle, and small-scale tourist excursions into space. Social, behavioural and communications data emerging from such existing communities in space suggest that the physically-bounded, work-oriented and traditionally male-dominated nature of these extremely remote groups present specific problems for the resident astronauts, groups of them viewed as ‘communities’, and their associated groups who remain on Earth, including mission controllers, management and astronauts’ families. Notionally feminine group attributes such as adaptive competence, social adaptation skills and social sensitivity will be crucial to the viability of space communities and in the absence of gender equity, ‘staying in touch’ by means of ‘news from home’ becomes more important than ever. A template of news and media forms and technologies is suggested to service those needs and enhance the social viability of future terraforming activities.

  9. Quantum correlations in Newtonian space and time: arbitrarily fast communication or nonlocality

    Gisin, Nicolas

    2013-03-01

    Experimental violations of Bell inequalities using space-like separated measurements precludes the explanation of quantum correlations through causal influences propagating at subluminal speed. Yet, ``everything looks as if the two parties somehow communicate behind the scene.'' We investigate the assumption that they do so at a speed faster than light, though finite. Such an assumption doesn't respect the spirit of Einstein relativity. However, it is not crystal clear that such ``communication behind the scene'' would contradict relativity. Indeed, one could imagine that this communication remains for ever hidden to humans, i.e. that it could not be controlled by humans, only Nature exploits it to produce correlations that can't be explained by usual common causes. To define faster than light hidden communication requires a universal privileged reference frame in which this faster than light speed is defined. Again, such a universal privileged frame is not in the spirit of relativity, but it is also clearly not in contradiction: for example the reference frame in which the cosmic microwave background radiation is isotropic defines such a privileged frame. Hence, a priori, a hidden communication explanation is not more surprising than nonlocality. We prove that for any finite speed, such models predict correlations that can be exploited for faster-than-light communication. This superluminal communication doesn't require access to any hidden physical quantities, but only the manipulation of measurement devices at the level of our present-day description of quantum experiments. Consequently, all possible explanations of quantum correlations that satisfy the principle of continuity, which states that everything propagates gradually and continuously through space and time, or in other words, all combination of local common causes and direct causes that reproduce quantum correlations, lead to faster than light communication. Accordingly, either there is superluminal

  10. Performance Analysis of Free-Space Optical Communication Systems With Multiuser Diversity Over Atmospheric Turbulence Channels

    Yang, Liang; Gao, Xiqi; Alouini, Mohamed-Slim

    2014-01-01

    Free-space optical (FSO) communication has become a cost-effective method to provide high data rates. However, the turbulence-induced fading limits its application to short-range applications. To address this, we propose a multiuser diversity (MD

  11. Is long distance free space quantum communication with the OAM state of light feasible [Presentation

    Hamadou Ibrahim, A

    2013-06-01

    Full Text Available -space quantum communication with the OAM state of light feasible? A. HAMADOU IBRAHIM1,2, F.S. ROUX1, M. McLAREN1,3 , A. FORBES1,2,3 & T. KONRAD2 1. CSIR National Laser Centre, PO Box 395, Pretoria 0001 2. School of Physics, University of Kwazulu...

  12. Free Space Optical (FSO) Communications, Towards the Speeds of Wireline Networks

    Alouini, Mohamed-Slim

    2015-01-01

    in the recent past, is not anymore a viable solution to fulfill the demand for more wireless applications and higher data rates. Among the many proposed solutions, optical wireless communication or free-space optical (FSO) systems have gained an increasing

  13. Visible laser and superluminescent diode based free space and underwater communications

    Ooi, Boon S.

    2017-01-30

    We report on our recent progress in high-modulation-efficiency, InGaN-based integrated waveguide modulator-laser diodes (IWM-LDs), high-speed violet and blue emitting superluminescent diodes (SLDs), InGaN-based vertical-cavity surface-emitting lasers (VCSELs), and their applications for gigahertz laser based free-space and underwater wireless optical communications.

  14. Spectral space-time coding for optical communications through a multimode fiber

    Alonso, A.; Berghmans, F.; Thienpont, H.; Danckaert, J.; Desmet, L.

    2001-01-01

    We propose a method for coding the mode structure of a multimode optical fiber by spectral coding mixed with space-time modulation. With this system we can improve the data carrying capacity of a multimode fiber for optical communications and optical interconnects, and encode and decode the

  15. The Association of Schools of Journalism and mass communication journalist-in-space project

    1986-01-01

    During the summer of 1985, NASA asked the Association of Schools of Journalism and Mass Communication (ASJMC) to select a U. S. journalist who could ride aboard the space shuttle and report the experience to the American public. Eligibility critieria and selection procedures are discussed. The forty semifinalists are listed.

  16. Small-Scale Design Experiments as Working Space for Larger Mobile Communication Challenges

    Lowe, Sarah; Stuedahl, Dagny

    2014-01-01

    In this paper, a design experiment using Instagram as a cultural probe is submitted as a method for analyzing the challenges that arise when considering the implementation of social media within a distributed communication space. It outlines how small, iterative investigations can reveal deeper research questions relevant to the education of…

  17. Visible laser and superluminescent diode based free space and underwater communications

    Ooi, Boon S.

    2017-01-01

    We report on our recent progress in high-modulation-efficiency, InGaN-based integrated waveguide modulator-laser diodes (IWM-LDs), high-speed violet and blue emitting superluminescent diodes (SLDs), InGaN-based vertical-cavity surface-emitting lasers (VCSELs), and their applications for gigahertz laser based free-space and underwater wireless optical communications.

  18. The Process of Science Communications at NASA/Marshall Space Flight Center

    Horack, John M.; Treise, Deborah

    1998-01-01

    The communication of new scientific knowledge and understanding is an integral component of science research, essential for its continued survival. Like any learning- based activity, science cannot continue without communication between and among peers so that skeptical inquiry and learning can take place. This communication provides necessary organic support to maintain the development of new knowledge and technology. However, communication beyond the peer-community is becoming equally critical for science to survive as an enterprise into the 21st century. Therefore, scientists not only have a 'noble responsibility' to advance and communicate scientific knowledge and understanding to audiences within and beyond the peer-community, but their fulfillment of this responsibility is necessary to maintain the survival of the science enterprise. Despite the critical importance of communication to the viability of science, the skills required to perform effective science communications historically have not been taught as a part of the training of scientist, and the culture of science is often averse to significant communication beyond the peer community. Thus scientists can find themselves ill equipped and uncomfortable with the requirements of their job in the new millennium. At NASA/Marshall Space Flight Center, we have developed and implemented an integrated science communications process, providing an institutional capability to help scientist accurately convey the content and meaning of new scientific knowledge to a wide variety of audiences, adding intrinsic value to the research itself through communication, while still maintaining the integrity of the peer-review process. The process utilizes initial communication through the world-wide web at the site http://science.nasa.gov to strategically leverage other communications vehicles and to reach a wide-variety of audiences. Here we present and discuss the basic design of the science communications process, now in

  19. Differential phase-shift keying and channel equalization in free space optical communication system

    Zhang, Dai; Hao, Shiqi; Zhao, Qingsong; Wan, Xiongfeng; Xu, Chenlu

    2018-01-01

    We present the performance benefits of differential phase-shift keying (DPSK) modulation in eliminating influence from atmospheric turbulence, especially for coherent free space optical (FSO) communication with a high communication rate. Analytic expression of detected signal is derived, based on which, homodyne detection efficiency is calculated to indicate the performance of wavefront compensation. Considered laser pulses always suffer from atmospheric scattering effect by clouds, intersymbol interference (ISI) in high-speed FSO communication link is analyzed. Correspondingly, the channel equalization method of a binormalized modified constant modulus algorithm based on set-membership filtering (SM-BNMCMA) is proposed to solve the ISI problem. Finally, through the comparison with existing channel equalization methods, its performance benefits of both ISI elimination and convergence speed are verified. The research findings have theoretical significance in a high-speed FSO communication system.

  20. 850-nm hybrid fiber/free-space optical communications using orbital angular momentum modes

    Jurado-Navas, Antonio; Tatarczak, Anna; Lu, Xiaofeng

    2015-01-01

    Light beams can carry orbital angular momentum (OAM) associated to the helicity of their phasefronts. These OAM modes can be employed to encode information onto a laser beam for transmitting not only in a fiber link but also in a free-space optical (FSO) one. Regarding this latter scenario, FSO...... communications are considered as an alternative and promising mean complementing the traditional optical communications in many applications where the use of fiber cable is not justified. This next generation FSO communication systems have attracted much interest recently, and the inclusion of beams carrying OAM...... modes can be seen as an efficient solution to increase the capacity and the security in the link. In this paper, we discuss an experimental demonstration of a proposal for next generation FSO communication system where a light beam carrying different OAM modes and affected by M turbulence is coupled...

  1. Transforming communicative spaces: the rhythm of gender in meetings in rural Solomon Islands

    Michelle Dyer

    2018-03-01

    Full Text Available Women's lack of participation in important decision making is noted as an obstacle to sustainable development in many parts of the world. An initial issue for gender equity in environmental decision making in many developing country contexts is not only women's inclusion but also their substantive participation in decision-making forums. In this article I examine the power structures embedded in the public communicative spaces in a village in the Western Province of Solomon Islands using empirical data in conjunction with ethnographic understanding of gendered meeting styles. The data reveal some reasons why women may be silenced as public political actors. It also raises the potential for development actors to create conceptual space for specific women's ways of meeting and validating women's meeting styles. These findings have implications for encouraging transformative communicative spaces and formats that allow transcendence of socially embedded power structures.

  2. Deep-space and near-Earth optical communications by coded orbital angular momentum (OAM) modulation.

    Djordjevic, Ivan B

    2011-07-18

    In order to achieve multi-gigabit transmission (projected for 2020) for the use in interplanetary communications, the usage of large number of time slots in pulse-position modulation (PPM), typically used in deep-space applications, is needed, which imposes stringent requirements on system design and implementation. As an alternative satisfying high-bandwidth demands of future interplanetary communications, while keeping the system cost and power consumption reasonably low, in this paper, we describe the use of orbital angular momentum (OAM) as an additional degree of freedom. The OAM is associated with azimuthal phase of the complex electric field. Because OAM eigenstates are orthogonal the can be used as basis functions for N-dimensional signaling. The OAM modulation and multiplexing can, therefore, be used, in combination with other degrees of freedom, to solve the high-bandwidth requirements of future deep-space and near-Earth optical communications. The main challenge for OAM deep-space communication represents the link between a spacecraft probe and the Earth station because in the presence of atmospheric turbulence the orthogonality between OAM states is no longer preserved. We will show that in combination with LDPC codes, the OAM-based modulation schemes can operate even under strong atmospheric turbulence regime. In addition, the spectral efficiency of proposed scheme is N2/log2N times better than that of PPM.

  3. Adaptive Coding and Modulation Experiment With NASA's Space Communication and Navigation Testbed

    Downey, Joseph; Mortensen, Dale; Evans, Michael; Briones, Janette; Tollis, Nicholas

    2016-01-01

    National Aeronautics and Space Administration (NASA)'s Space Communication and Navigation Testbed is an advanced integrated communication payload on the International Space Station. This paper presents results from an adaptive coding and modulation (ACM) experiment over S-band using a direct-to-earth link between the SCaN Testbed and the Glenn Research Center. The testing leverages the established Digital Video Broadcasting Second Generation (DVB-S2) standard to provide various modulation and coding options, and uses the Space Data Link Protocol (Consultative Committee for Space Data Systems (CCSDS) standard) for the uplink and downlink data framing. The experiment was conducted in a challenging environment due to the multipath and shadowing caused by the International Space Station structure. Several approaches for improving the ACM system are presented, including predictive and learning techniques to accommodate signal fades. Performance of the system is evaluated as a function of end-to-end system latency (round-trip delay), and compared to the capacity of the link. Finally, improvements over standard NASA waveforms are presented.

  4. Space Weather effects on airline communications in the high latitude regions

    Honary, Farideh

    2014-05-01

    Efficient air traffic management depends on reliable communications between aircraft and the air traffic control centres at all times. At high latitudes, and especially on polar routing, VHF ground infrastructure does not exist and the aircraft have to rely on HF radio for communications. HF relies on reflections from the ionosphere to achieve long distance communications. Unfortunately the high latitude ionosphere is affected by space weather events. During such events HF radio communication can be severely disrupted and aircraft are forced to use longer low latitude routes with consequent increased flight time, fuel consumption and cost. This presentation describes a new research programme at the University of Lancaster in collaboration with the University of Leicester, Solar Metrics Ltd and Natural Resources Canada for the development of a nowcasting and forecasting HF communications tool designed for the particular needs of civilian airlines. This project funded by EPSRC will access a wide variety of solar and interplanetary measurements to derive a complete picture of space weather disturbances affecting radio absorption and reflection

  5. Variable Coding and Modulation Experiment Using NASA's Space Communication and Navigation Testbed

    Downey, Joseph A.; Mortensen, Dale J.; Evans, Michael A.; Tollis, Nicholas S.

    2016-01-01

    National Aeronautics and Space Administration (NASA)'s Space Communication and Navigation Testbed on the International Space Station provides a unique opportunity to evaluate advanced communication techniques in an operational system. The experimental nature of the Testbed allows for rapid demonstrations while using flight hardware in a deployed system within NASA's networks. One example is variable coding and modulation, which is a method to increase data-throughput in a communication link. This paper describes recent flight testing with variable coding and modulation over S-band using a direct-to-earth link between the SCaN Testbed and the Glenn Research Center. The testing leverages the established Digital Video Broadcasting Second Generation (DVB-S2) standard to provide various modulation and coding options. The experiment was conducted in a challenging environment due to the multipath and shadowing caused by the International Space Station structure. Performance of the variable coding and modulation system is evaluated and compared to the capacity of the link, as well as standard NASA waveforms.

  6. Color-Space-Based Visual-MIMO for V2X Communication

    Jai-Eun Kim; Ji-Won Kim; Youngil Park; Ki-Doo Kim

    2016-01-01

    In this paper, we analyze the applicability of color-space-based, color-independent visual-MIMO for V2X. We aim to achieve a visual-MIMO scheme that can maintain the original color and brightness while performing seamless communication. We consider two scenarios of GCM based visual-MIMO for V2X. One is a multipath transmission using visual-MIMO networking and the other is multi-node V2X communication. In the scenario of multipath transmission, we analyze the channel capacity numerically and w...

  7. Distress detection, location, and communications using advanced space technology. [satellite-borne synthetic aperture radar

    Sivertson, W. E., Jr.

    1977-01-01

    This paper briefly introduces a concept for low-cost, global, day-night, all-weather disaster warning and assistance. Evolving, advanced space technology with passive radio frequency reflectors in conjunction with an imaging synthetic aperture radar is employed to detect, identify, locate, and provide passive communication with earth users in distress. This concept evolved from a broad NASA research on new global search and rescue techniques. Appropriate airborne radar test results from this research are reviewed and related to potential disaster applications. The analysis indicates the approach has promise for disaster communications relative to floods, droughts, earthquakes, volcanic eruptions, and severe storms.

  8. Using the Electronic Medical Record to Enhance Physician-Nurse Communication Regarding Patients' Discharge Status.

    Driscoll, Molly; Gurka, David

    2015-01-01

    The fast-paced environment of hospitals contributes to communication failures between health care providers while impacting patient care and patient flow. An effective mechanism for sharing patients' discharge information with health care team members is required to improve patient throughput. The communication of a patient's discharge plan was identified as crucial in alleviating patient flow delays at a tertiary care, academic medical center. By identifying the patients who were expected to be discharged the following day, the health care team could initiate discharge preparations in advance to improve patient care and patient flow. The patients' electronic medical record served to convey dynamic information regarding the patients' discharge status to the health care team via conditional discharge orders. Two neurosciences units piloted a conditional discharge order initiative. Conditional discharge orders were designed in the electronic medical record so that the conditions for discharge were listed in a dropdown menu. The health care team was trained on the conditional discharge order protocol, including when to write them, how to find them in the patients' electronic medical record, and what actions should be prompted by these orders. On average, 24% of the patients discharged had conditional discharge orders written the day before discharge. The average discharge time for patients with conditional discharge orders decreased by 83 minutes (0.06 day) from baseline. Qualitatively, the health care team reported improved workflows with conditional orders. The conditional discharge orders allowed physicians to communicate pending discharges electronically to the multidisciplinary team. The initiative positively impacted patient discharge times and workflows.

  9. Roles of Cognitive Status and Intelligibility in Everyday Communication in People with Parkinson's Disease: A Systematic Review.

    Barnish, Maxwell S; Whibley, Daniel; Horton, Simon M C; Butterfint, Zoe R; Deane, Katherine H O

    2016-03-16

    Communication is fundamental to human interaction and the development and maintenance of human relationships and is frequently affected in Parkinson's disease (PD). However, research and clinical practice have both tended to focus on impairment rather than participation aspects of communicative deficit in PD. In contrast, people with PD have reported that it is these participation aspects of communication that are of greatest concern to them rather than physical speech impairment. To systematically review the existing body of evidence regarding the association between cognitive status and/or intelligibility and everyday communication in PD. Five online databases were systematically searched in May 2015 (Medline Ovid, EMBASE, AMED, PsycINFO and CINAHL) and supplementary searches were also conducted. Two reviewers independently evaluated retrieved records for inclusion and then performed data extraction and quality assessment using standardised forms. Articles were eligible for inclusion if they were English-language original peer-reviewed research articles, book chapters or doctoral theses investigating the associations between at least one of cognitive status and level of intelligibility impairment and an everyday communication outcome in human participants with PD. 4816 unique records were identified through database searches with 16 additional records identified through supplementary searches. 41 articles were suitable for full-text screening and 15 articles (12 studies) met the eligibility criteria. 10 studies assessed the role of cognitive status and 9 found that participants with greater cognitive impairment had greater everyday communication difficulties. 4 studies assessed the role of intelligibility and all found that participants with greater intelligibility impairment had greater everyday communication difficulties, although effects were often weak and not consistent. Both cognitive status and intelligibility may be associated with everyday communicative

  10. Free-space laser communication technologies II; Proceedings of the Meeting, Los Angeles, CA, Jan. 15-17, 1990

    Begley, David L. (Editor); Seery, Bernard D. (Editor)

    1990-01-01

    Various papers on free-space laser communication technologies are presented. Individual topics addressed include: optical intersatellite link experiment between the earth station and ETS-VI, the Goddard optical communications program, technologies and techniques for lasercom terminal size, weight, and cost reduction, laser beam acquisition and tracking system for ETS-VI laser communication equipment, analog dividers for acquisition and tracking signal normalization, fine pointing mechanism using multilayered piezoelectric actuator for optical ISL system, analysis of SILEX tracking sensor performance, new telescope concept for space communication, telescope considered as a very high gain antenna, design of compact transceiver optical systems for optical intersatellite links, ultralightweight optics for laser communications, highly sensitive measurement method for stray light and retroreflected light, depolarization effects on free space laser transceiver communication systems, in-orbit measurements of microaccelerations of ESA's communication satellite Olympus, high-performance laser diode transmitter for optical free space communication, diode-pumped Nd:host laser transmitter for intersatellite optical communications, single-frequency diode-pumped laser for free-space communication.

  11. The source of net ultrafiltration during hemodialysis is mostly the extracellular space regardless of hydration status.

    Jeong, Hyeonju; Lim, Chae-Wan; Choi, Hye-Min; Oh, Dong-Jin

    2016-01-01

    Fluid shifts are common in patients undergoing chronic hemodialysis (HD) during the intradialytic periods, as several liters of fluid are removed during ultrafiltration (UF). Some patients have experienced frequent intradialytic hypotension (IDH). However, the characteristics of fluid shifts and which fluid space is affected remain controversial. Therefore, we designed this study to evaluate the fluid spaces most affected by UF and to determine whether hydration status influences the fluid shifts during HD. This was a prospective cohort study of 40 patients undergoing HD. We measured the patient's fluid spaces using a whole-body bioimpedance apparatus to evaluate the changes in the fluid spaces before HD and 1-4 hours of HD and 30 minutes after HD. UF achieved during HD by the 40 patients (age, 60.0 ± 5.2 years; 50% men; 50% of patients with diabetes; body weight, 61.3 ± 10.5 kg) was 2.18 ± 0.78 L (measured fluid overload, 2.15 ± 1.24 L). 1) Mean relative reduction of total body water and extracellular water was reduced from the start to the end of HD. 2) However, mean relative reduction of intracellular water was not reduced from the start to the end of HD. 3) No significant differences in fluid shifts were observed according to hydration status. The source of net UF during HD is mostly the extracellular space regardless of hydration status. Thus, IDH may be related to differences in the interstitial fluid shift to the vascular space. © 2015 International Society for Hemodialysis.

  12. Green Space and Child Weight Status: Does Outcome Measurement Matter? Evidence from an Australian Longitudinal Study

    Taren Sanders

    2015-01-01

    Full Text Available Objective. To examine whether neighbourhood green space is beneficially associated with (i waist circumference (WC and (ii waist-to-height ratio (WtHR across childhood. Methods. Gender-stratified multilevel linear regressions were used to examine associations between green space and objective measures of weight status in the Longitudinal Study of Australian Children, a nationally representative source of data on 4,423 children aged 6 y to 13 y. WC and WtHR were measured objectively. Percentage green space within the local area of residence was calculated. Effect modification by age was explored, adjusting for socioeconomic confounding. Results. Compared to peers with 0–5% green space locally, boys and girls with >40% green space tended to have lower WC (βboys  −1.15, 95% CI −2.44, 0.14; βgirls  −0.21, 95% CI −1.47, 1.05 and WtHR (βboys  −0.82, 95% CI −1.65, 0.01; βgirls  −0.32, 95% CI −1.13, 0.49. Associations among boys were contingent upon age (p  valuesage∗green  space40% green space at 73.85 cm and 45.75% compared to those with 0–5% green space at 75.18 cm and 46.62%, respectively. Conclusions. Greener neighbourhoods appear beneficial to alternative child weight status measures, particularly among boys.

  13. Free-space laser communication technologies III; Proceedings of the Meeting, Los Angeles, CA, Jan. 21, 22, 1991

    Begley, David L. (Editor); Seery, Bernard D. (Editor)

    1991-01-01

    The present volume on free-space laser communication technologies discusses system analysis, performance, and applications, pointing, acquisition, and tracking in beam control, laboratory demonstration systems, and transmitter and critical component technologies. Attention is given to a space station laser communication transceiver, meeting intersatellite links mission requirements by an adequate optical terminal design, an optical approach to proximity-operations communications for Space Station Freedom, and optical space-to-ground link availability assessment and diversity requirements. Topics addressed include nonmechanical steering of laser beams by multiple aperture antennas, a free-space simulator for laser transmission, heterodyne acquisition and tracking in a free-space diode laser link, and laser terminal attitude determination via autonomous star tracking. Also discussed are stability considerations in relay lens design for optical communications, liquid crystals for lasercom applications, and narrowband optical interference filters.

  14. Morphological and Hemodynamic Discriminators for Rupture Status in Posterior Communicating Artery Aneurysms.

    Lv, Nan; Wang, Chi; Karmonik, Christof; Fang, Yibin; Xu, Jinyu; Yu, Ying; Cao, Wei; Liu, Jianmin; Huang, Qinghai

    2016-01-01

    The conflicting findings of previous morphological and hemodynamic studies on intracranial aneurysm rupture may be caused by the relatively small sample sizes and the variation in location of the patient-specific aneurysm models. We aimed to determine the discriminators for aneurysm rupture status by focusing on only posterior communicating artery (PCoA) aneurysms. In 129 PCoA aneurysms (85 ruptured, 44 unruptured), clinical, morphological and hemodynamic characteristics were compared between the ruptured and unruptured cases. Multivariate logistic regression analysis was performed to determine the discriminators for rupture status of PCoA aneurysms. While univariate analyses showed that the size of aneurysm dome, aspect ratio (AR), size ratio (SR), dome-to-neck ratio (DN), inflow angle (IA), normalized wall shear stress (NWSS) and percentage of low wall shear stress area (LSA) were significantly associated with PCoA aneurysm rupture status. With multivariate analyses, significance was only retained for higher IA (OR = 1.539, p PCoA aneurysms.

  15. Socioeconomic status, health inequalities and non-communicable diseases: a systematic review.

    Lago, Santiago; Cantarero, David; Rivera, Berta; Pascual, Marta; Blázquez-Fernández, Carla; Casal, Bruno; Reyes, Francisco

    2018-01-01

    A comprehensive approach to health highlights its close relationship with the social and economic conditions, physical environment and individual lifestyles. However, this relationship is not exempt from methodological problems that may bias the establishment of direct effects between the variables studied. Thus, further research is necessary to investigate the role of socioeconomic variables, their composition and distribution according to health status, particularly on non-communicable diseases. To shed light on this field, here a systematic review is performed using PubMed, the Cochrane Library and Web of Science. A 7-year retrospective horizon was considered until 21 July 2017. Twenty-six papers were obtained from the database search. Additionally, results from "hand searching" were also included, where a wider horizon was considered. Five of the 26 studies analyzed used aggregated data compared to 21 using individual data. Eleven considered income as a study variable, while 17 analyzed the effect of income inequality on health status (2 of the studies considered both the absolute level and distribution of income). The most used indicator of inequality in the literature was the Gini index. Although different types of analysis produce very different results concerning the role of health determinants, the general conclusion is that income distribution is related to health where it represents a measure of the differences in social class in the society. The effect of income inequality is to increase the gap between social classes or to widen differences in status.

  16. Essential Biodiversity Variables: A framework for communication between the biodiversity community and space agencies

    Leidner, A. K.; Skidmore, A. K.; Turner, W. W.; Geller, G. N.

    2017-12-01

    The biodiversity community is working towards developing a consensus on a set of Essential Biodiversity Variables (EBVs) that can be used to measure and monitor biodiversity change over time. These EBVs will inform research, modeling, policy, and assessment efforts. The synoptic coverage provided by satellite data make remote sensing a particularly important observation tool to inform many EBVs. Biodiversity is a relatively new subject matter for space agencies, and thus the definition, description, and requirements of EBVs with a significant remote sensing component can foster ways for the biodiversity community to clearly and concisely communicate observational needs to space agencies and the Committee on Earth Observing Satellites (CEOS, the international coordinating body for civilian space agencies). Here, we present an overview of EBVs with a particular emphasis on those for which remote sensing will play a significant role and also report on the results of recent workshops to prioritize and refine EBVs. Our goal is to provide a framework for the biodiversity community to coalesce around a set of observational needs to convey to space agencies. Compared to many physical science disciplines, the biodiversity community represents a wide range of sub-disciplines and organizations (academia, non-governmental organizations, research institutes, national and local natural resource management agencies, etc.), which creates additional challenges when communicating needs to space agencies unfamiliar with the topic. EBVs thus offer a communication pathway that could increase awareness within space agencies of the uses of remote sensing for biodiversity research and applications, which in turn could foster greater use of remote sensing in the broader biodiversity community.

  17. Mobile free-space optical communications: a feasibility study of various battlefield scenarios

    Harris, Alan; Al-Akkoumi, Mouhammad K.; Sluss, James J., Jr.

    2012-06-01

    Free Space Optics (FSO) technology was originally envisioned to be a viable solution for the provision of high bandwidth optical connectivity in the last mile of today's telecommunications infrastructure. Due to atmospheric limitations inherent to FSO technology, FSO is now widely envisioned as a solution for the provision of high bandwidth, temporary mobile communications links. The need for FSO communications links will increase as mobility is introduced to this technology. In this paper, a theoretical solution for adding mobility to FSO communication links is introduced. Three-dimensional power estimation studies are presented to represent mobile FSO transmission under various weather conditions. Three wavelengths, 0.85, 1.55 and 10 um, are tested and compared to illustrate the pros and cons of each source wavelength used for transmission, depending on prevalent weather conditions and atmospheric turbulence conditions. A simulation analysis of the transmission properties of the source wavelengths used in the study is shown.

  18. Reduced-Complexity Wireless Transceiver Architectures and Techniques for Space-Time Communications

    Tsakalaki, Elpiniki

    2012-01-01

    The dissertation sheds light on the performance gains of multi-antenna systems when the antenna aspects and the associated signal processing and coding aspects are integrated together in a multidisciplinary approach, addressing a variety of challenging tasks pertaining to the joint design of smart...... wireless transceivers and communication techniques. These tasks are at the intersection of different scientific disciplines including signal processing, communications, antennas and propagation. Specifically, the thesis deals with reduced-complexity space-time wireless transceiver architectures...... and associated communication techniques for multi-input multi-output (MIMO) and cognitive radio (CR) systems as well as wireless sensor networks (WSNs). The low-complexity architectures are obtained by equipping the wireless transceiver with passive control ports which require the minimum amount of RF hardware...

  19. Educational status and beliefs regarding non-communicable diseases among children in Ghana.

    Badasu, Delali M; Abuosi, Aaron A; Adzei, Francis A; Anarfi, John K; Yawson, Alfred E; Atobrah, Deborah A

    2018-03-05

    Increasing prevalence of non-communicable diseases (NCDs) has been observed in Ghana as in other developing countries. Past research focused on NCDs among adults. Recent researches, however, provide evidence on NCDs among children in many countries, including Ghana. Beliefs about the cause of NCDs among children may be determined by the socioeconomic status of parents and care givers. This paper examines the relationship between educational status of parents and/or care givers of children with NCDs on admission and their beliefs regarding NCDs among children. A total of 225 parents and/or care givers of children with NCDS hospitalized in seven hospitals in three regions (Greater Accra, Ashanti and Volta) were selected for the study. Statistical techniques, including the chi-square and multinomial logistic regression, were used for the data analysis. Educational status is a predictor of care giver's belief about whether enemies can cause NCDs among children or not. This is the only belief with which all the educational categories have significant relationship. Also, post-secondary/polytechnic (p-value =0.029) and university (p-value = 0.009) levels of education are both predictors of care givers being undecided about the belief that NCDs among children can be caused by enemies, when background characteristics are controlled for. Significant relationship is found between only some educational categories regarding the other types of beliefs and NCDs among children. For example, those with Middle/Juniour Secondary School (JSS)/Juniour High School (JHS) education are significantly undecided about the belief that the sin of parents can cause NCDs among children. Education is more of a predictor of the belief that enemies can cause NCDs among children than the other types of beliefs. Some categories of ethnicity, residential status and age have significant relationship with the beliefs when background characteristics of the parents and/or care givers were controlled

  20. High-dimensional free-space optical communications based on orbital angular momentum coding

    Zou, Li; Gu, Xiaofan; Wang, Le

    2018-03-01

    In this paper, we propose a high-dimensional free-space optical communication scheme using orbital angular momentum (OAM) coding. In the scheme, the transmitter encodes N-bits information by using a spatial light modulator to convert a Gaussian beam to a superposition mode of N OAM modes and a Gaussian mode; The receiver decodes the information through an OAM mode analyser which consists of a MZ interferometer with a rotating Dove prism, a photoelectric detector and a computer carrying out the fast Fourier transform. The scheme could realize a high-dimensional free-space optical communication, and decodes the information much fast and accurately. We have verified the feasibility of the scheme by exploiting 8 (4) OAM modes and a Gaussian mode to implement a 256-ary (16-ary) coding free-space optical communication to transmit a 256-gray-scale (16-gray-scale) picture. The results show that a zero bit error rate performance has been achieved.

  1. Interfacing Space Communications and Navigation Network Simulation with Distributed System Integration Laboratories (DSIL)

    Jennings, Esther H.; Nguyen, Sam P.; Wang, Shin-Ywan; Woo, Simon S.

    2008-01-01

    NASA's planned Lunar missions will involve multiple NASA centers where each participating center has a specific role and specialization. In this vision, the Constellation program (CxP)'s Distributed System Integration Laboratories (DSIL) architecture consist of multiple System Integration Labs (SILs), with simulators, emulators, testlabs and control centers interacting with each other over a broadband network to perform test and verification for mission scenarios. To support the end-to-end simulation and emulation effort of NASA' exploration initiatives, different NASA centers are interconnected to participate in distributed simulations. Currently, DSIL has interconnections among the following NASA centers: Johnson Space Center (JSC), Kennedy Space Center (KSC), Marshall Space Flight Center (MSFC) and Jet Propulsion Laboratory (JPL). Through interconnections and interactions among different NASA centers, critical resources and data can be shared, while independent simulations can be performed simultaneously at different NASA locations, to effectively utilize the simulation and emulation capabilities at each center. Furthermore, the development of DSIL can maximally leverage the existing project simulation and testing plans. In this work, we describe the specific role and development activities at JPL for Space Communications and Navigation Network (SCaN) simulator using the Multi-mission Advanced Communications Hybrid Environment for Test and Evaluation (MACHETE) tool to simulate communications effects among mission assets. Using MACHETE, different space network configurations among spacecrafts and ground systems of various parameter sets can be simulated. Data that is necessary for tracking, navigation, and guidance of spacecrafts such as Crew Exploration Vehicle (CEV), Crew Launch Vehicle (CLV), and Lunar Relay Satellite (LRS) and orbit calculation data are disseminated to different NASA centers and updated periodically using the High Level Architecture (HLA). In

  2. GPS and Galileo Developments on Board the International Space Station With the Space Communications and Navigation (SCaN) Testbed

    Pozzobon, Oscar; Fantinato, Samuele; Dalla Chiara, Andrea; Gamba, Giovanni; Crisci, Massimo; Giordana, Pietro; Enderle, Werner; Chelmins, David; Sands, Obed S.; Clapper, Carolyn J.; hide

    2016-01-01

    The Space Communications and Navigation (SCaN) is a facility developed by NASA and hosted on board the International Space Station (ISS) on an external truss since 2013.It has the objective of testing navigation and communication experimentations with a Software Defined Radio (SDR) approach, which permits software updates for testing new experimentations.NASA has developed the Space Telecommunications Radio System (STRS) architecture standard for SDRs used in space and ground-based platforms to provide commonality among radio developments to provide enhanced capability. The hardware is equipped with both L band front-end radios and the NASA space network communicates with it using S-band, Ku-band and Ka-band links.In May 2016 Qascom started GARISS (GPS and Galileo Receiver for the ISS), an activity of experimentation in collaboration with ESA and NASA that has the objective to develop and validate the acquisition and processing of combined GPS and Galileo signals on board the ISS SCaN testbed. This paper has the objective to present the mission, and provide preliminary details about the challenges in the design, development and verification of the waveform that will be installed on equipment with limited resources. GARISS is also the first attempt to develop a waveform for the ISS as part of an international collaboration between US and Europe. Although the final mission objective is to target dual frequency processing, initial operations will foresee a single frequency processing. Initial results and trade-off between the two options, as well as the final decision will be presented and discussed. The limited resources on board the SCaN with respect to the challenging requirements to acquire and track contemporaneously two satellite navigation systems, with different modulations and data structure, led to the need to assess the possibility of aiding from ground through the S-band. This option would allow assistance to the space receiver in order to provide

  3. Geostationary Communications Satellites as Sensors for the Space Weather Environment: Telemetry Event Identification Algorithms

    Carlton, A.; Cahoy, K.

    2015-12-01

    Reliability of geostationary communication satellites (GEO ComSats) is critical to many industries worldwide. The space radiation environment poses a significant threat and manufacturers and operators expend considerable effort to maintain reliability for users. Knowledge of the space radiation environment at the orbital location of a satellite is of critical importance for diagnosing and resolving issues resulting from space weather, for optimizing cost and reliability, and for space situational awareness. For decades, operators and manufacturers have collected large amounts of telemetry from geostationary (GEO) communications satellites to monitor system health and performance, yet this data is rarely mined for scientific purposes. The goal of this work is to acquire and analyze archived data from commercial operators using new algorithms that can detect when a space weather (or non-space weather) event of interest has occurred or is in progress. We have developed algorithms, collectively called SEER (System Event Evaluation Routine), to statistically analyze power amplifier current and temperature telemetry by identifying deviations from nominal operations or other events and trends of interest. This paper focuses on our work in progress, which currently includes methods for detection of jumps ("spikes", outliers) and step changes (changes in the local mean) in the telemetry. We then examine available space weather data from the NOAA GOES and the NOAA-computed Kp index and sunspot numbers to see what role, if any, it might have played. By combining the results of the algorithm for many components, the spacecraft can be used as a "sensor" for the space radiation environment. Similar events occurring at one time across many component telemetry streams may be indicative of a space radiation event or system-wide health and safety concern. Using SEER on representative datasets of telemetry from Inmarsat and Intelsat, we find events that occur across all or many of

  4. [Current status on storage, processing and risk communication of medical radioactive waste in Japan].

    Watanabe, Hiroshi; Yamaguchi, Ichiro; Kida, Tetsuo; Hiraki, Hitoshi; Fujibuchi, Toshioh; Maehara, Yoshiaki; Tsukamoto, Atsuko; Koizumi, Mitsue; Kimura, Yumi; Horitsugi, Genki

    2013-03-01

    Decay-in-storage for radioactive waste including that of nuclear medicine has not been implemented in Japan. Therefore, all medical radioactive waste is collected and stored at the Japan Radioisotope Association Takizawa laboratory, even if the radioactivity has already decayed out. To clarify the current situation between Takizawa village and Takizawa laboratory, we investigated the radiation management status and risk communication activities at the laboratory via a questionnaire and site visiting survey in June 2010. Takizawa laboratory continues to maintain an interactive relationship with local residents. As a result, Takizawa village permitted the acceptance of new medical radioactive waste containing Sr-89 and Y-90. However, the village did not accept any non-medical radioactive waste such as waste from research laboratories. To implement decay-in-storage in Japan, it is important to obtain agreement with all stakeholders. We must continue to exert sincere efforts to acquire the trust of all stakeholders.

  5. Acousto-optic pointing and tracking systems for free-space laser communications

    Nikulin, V.; Khandekar, R.; Sofka, J.; Tartakovsky, G.

    2005-08-01

    Implementation of long-range laser communication systems holds great promise for high-bandwidth applications. They are viewed as a technology that in the nearest future will handle most of the "last mile" communication traffic for the individual subscribers, corporate offices, military, and possibly deep space probes. Indeed, lasers allow for concentration of energy within tightly focused beams and narrow spectral interval, thus offering high throughput, information security, weight and size of components and power requirements that could not be matched by RF systems. However, the advantages of optical communication systems come in the same package with several major challenges. In particular, high data rates should be complemented by high-precision wide-bandwidth position control of a laser beam. In many applications the ability to maintain a link is affected by the complex maneuvers performed by mobile communication platforms, resident vibrations, and atmospheric effects. The search for the most effective and reliable way to shape and steer the laser beam is an on-going effort. This paper is focused on the application of acousto-optic technology as an alternative to electro-mechanical devices. With realization that an acousto-optic Bragg cell is only a component of the entire communication system, which should perform complex tasks of acquisition, pointing, and tracking of the remote terminal, we present an attempt to consider this problem from the "systems" point of view.

  6. Color-Space-Based Visual-MIMO for V2X Communication

    Kim, Jai-Eun; Kim, Ji-Won; Park, Youngil; Kim, Ki-Doo

    2016-01-01

    In this paper, we analyze the applicability of color-space-based, color-independent visual-MIMO for V2X. We aim to achieve a visual-MIMO scheme that can maintain the original color and brightness while performing seamless communication. We consider two scenarios of GCM based visual-MIMO for V2X. One is a multipath transmission using visual-MIMO networking and the other is multi-node V2X communication. In the scenario of multipath transmission, we analyze the channel capacity numerically and we illustrate the significance of networking information such as distance, reference color (symbol), and multiplexing-diversity mode transitions. In addition, in the V2X scenario of multiple access, we may achieve the simultaneous multiple access communication without node interferences by dividing the communication area using image processing. Finally, through numerical simulation, we show the superior SER performance of the visual-MIMO scheme compared with LED-PD communication and show the numerical result of the GCM based visual-MIMO channel capacity versus distance. PMID:27120603

  7. Color-Space-Based Visual-MIMO for V2X Communication

    Jai-Eun Kim

    2016-04-01

    Full Text Available In this paper, we analyze the applicability of color-space-based, color-independent visual-MIMO for V2X. We aim to achieve a visual-MIMO scheme that can maintain the original color and brightness while performing seamless communication. We consider two scenarios of GCM based visual-MIMO for V2X. One is a multipath transmission using visual-MIMO networking and the other is multi-node V2X communication. In the scenario of multipath transmission, we analyze the channel capacity numerically and we illustrate the significance of networking information such as distance, reference color (symbol, and multiplexing-diversity mode transitions. In addition, in the V2X scenario of multiple access, we may achieve the simultaneous multiple access communication without node interferences by dividing the communication area using image processing. Finally, through numerical simulation, we show the superior SER performance of the visual-MIMO scheme compared with LED-PD communication and show the numerical result of the GCM based visual-MIMO channel capacity versus distance.

  8. Free Space Optical (FSO) Communications, Towards the Speeds of Wireline Networks

    Alouini, Mohamed-Slim

    2015-01-07

    Rapid increase in the use of wireless services over the last two decades has lead the problem of the radio-frequency (RF) spectrum exhaustion. More specifically, due to this RF spectrum scarcity, additional RF bandwidth allocation, as utilized in the recent past, is not anymore a viable solution to fulfill the demand for more wireless applications and higher data rates. Among the many proposed solutions, optical wireless communication or free-space optical (FSO) systems have gained an increasing interest due to their advantages including higher bandwidth and higher capacity compared to the traditional RF communication systems. This promising technology offers full-duplex Gigabit throughput in certain applications and environment while benefiting from a huge license-free spectrum, immunity to interference, and high security. These features of FSO communication systems potentially enable solving the issues that the RF communication systems face due to the expensive and scarce RF spectrum. The first part of the talk will give an overview of FSO communication systems by offering examples of advantages and application areas of this emerging technology. In the second part of talk, we will focus on some recent results and on-going research directions in the accurate characterization of the performance of FSO systems in the presence of inevitable impairments due to atmospheric turbulence and misalignment between transmitter and receiver.

  9. Color-Space-Based Visual-MIMO for V2X Communication.

    Kim, Jai-Eun; Kim, Ji-Won; Park, Youngil; Kim, Ki-Doo

    2016-04-23

    In this paper, we analyze the applicability of color-space-based, color-independent visual-MIMO for V2X. We aim to achieve a visual-MIMO scheme that can maintain the original color and brightness while performing seamless communication. We consider two scenarios of GCM based visual-MIMO for V2X. One is a multipath transmission using visual-MIMO networking and the other is multi-node V2X communication. In the scenario of multipath transmission, we analyze the channel capacity numerically and we illustrate the significance of networking information such as distance, reference color (symbol), and multiplexing-diversity mode transitions. In addition, in the V2X scenario of multiple access, we may achieve the simultaneous multiple access communication without node interferences by dividing the communication area using image processing. Finally, through numerical simulation, we show the superior SER performance of the visual-MIMO scheme compared with LED-PD communication and show the numerical result of the GCM based visual-MIMO channel capacity versus distance.

  10. Multi-aperture digital coherent combining for free-space optical communication receivers.

    Geisler, David J; Yarnall, Timothy M; Stevens, Mark L; Schieler, Curt M; Robinson, Bryan S; Hamilton, Scott A

    2016-06-13

    Space-to-ground optical communication systems can benefit from reducing the size, weight, and power profiles of space terminals. One way of reducing the required power-aperture product on a space platform is to implement effective, but costly, single-aperture ground terminals with large collection areas. In contrast, we present a ground terminal receiver architecture in which many small less-expensive apertures are efficiently combined to create a large effective aperture while maintaining excellent receiver sensitivity. This is accomplished via coherent detection behind each aperture followed by digitization. The digitized signals are then combined in a digital signal processing chain. Experimental results demonstrate lossless coherent combining of four lasercom signals, at power levels below 0.1 photons/bit/aperture.

  11. Data transmission with twisted light through a free-space to fiber optical communication link

    Brüning, Robert; Duparré, Michael; Ndagano, Bienvenu; McLaren, Melanie; Forbes, Andrew; Schröter, Siegmund; Kobelke, Jens

    2016-01-01

    Mode division multiplexing (MDM), where information is transmitted in the spatial modes of light, is mooted as a future technology with which to transmit large bits of information. However, one of the key issues in optical communication lies in connecting free-space to optical fiber networks, otherwise known as the ‘last mile’ problem. This is particularly problematic for MDM as the eigenmodes of free-space and fibers are in general not the same. Here we demonstrate a data transmission scheme across a free-space and fiber link using twisted light in the form of Laguerre–Gaussian (LG) azimuthal modes. As a proof-of-principle we design and implement a custom fiber where the supported LG modes can be grouped into five non-degenerate sets, and successfully transmit a gray-scale image across the composite link using one mode from each group, thereby ensuring minimal crosstalk. (letter)

  12. Advances in gallium arsenide monolithic microwave integrated-circuit technology for space communications systems

    Bhasin, K. B.; Connolly, D. J.

    1986-01-01

    Future communications satellites are likely to use gallium arsenide (GaAs) monolithic microwave integrated-circuit (MMIC) technology in most, if not all, communications payload subsystems. Multiple-scanning-beam antenna systems are expected to use GaAs MMIC's to increase functional capability, to reduce volume, weight, and cost, and to greatly improve system reliability. RF and IF matrix switch technology based on GaAs MMIC's is also being developed for these reasons. MMIC technology, including gigabit-rate GaAs digital integrated circuits, offers substantial advantages in power consumption and weight over silicon technologies for high-throughput, on-board baseband processor systems. In this paper, current developments in GaAs MMIC technology are described, and the status and prospects of the technology are assessed.

  13. Workers Experience Guides Karaoke in Updating Status in Facebook as Interpersonal Relations and Personal Communication with Customers

    Amelia Sari, Kiki; Suprihartini, M.Si, Dra. Taufik

    2016-01-01

    The presence of information technology is rapid and practical nature can allow for changes in behavior or lifestyle. One of them is the development of information technology with the birth of social networks, namely Facebook. Karaoke guide also actively uses Facebook to update your status and communicate with customers. By using qualitative methods, this study aims to describe the "Experience of Guides Karaoke Workers when Updating status on Facebook as Interpersonal and Personality Communica...

  14. Non-Mechanical Beam Steering in Free-Space Optical Communication Transceivers

    Shortt, Kevin

    Free-space optical communications systems are a rapidly growing field as they carry many of the advantages of traditional fibre-based communications systems without the added investment of installing complex infrastructure. Moreover, these systems are finding key niches in mobile platforms in order to take advantage of the increased bandwidth over traditional RF systems. Of course, the inevitable problem of tracking arises when dealing with mobile stations. To compound the problem in the case of communications to low Earth or geosynchronous orbits, FSOC systems typically operate with tightly confined beams over great distances often requiring pointing accuracies on the order of micro-radians or smaller. Mechanisms such as gimbal mounts and fine-steering mirrors are the usual candidates for platform stabilization, however, these clearly have substantial power requirements and inflate the mass of the system. Spatial light modulators (also known as optical phased arrays), on the other hand, offer a suitable alternative for beam-pointing stabilization. Some of the advantages of spatial light modulators over fine-steering mirrors include programmable multiple simultaneous beams, dynamic focus/defocus and moderate to excellent optical power handling capability. This thesis serves as an investigation into the implementation of spatial light modulators as a replacement for traditional fine-steering mirrors in the fine-pointing subsystem. In particular, pointing accuracy and scanning ability will be highlighted as performance metrics in the context of a variety of communication scenarios. Keywords: Free-space optical communications, beam steering, fine-steering mirror, spatial light modulator, optical phased array.

  15. Compact mobile-reader system for two-way wireless communication, tracking and status monitoring for transport safety and security

    Tsai, Han-Chung; Liu, Yung Y.; Lee, Hok L.; Craig, Brian; Byrne, Kevin; Mittal, Ketan; Scherer, Justin C.

    2016-12-06

    A system for monitoring a plurality radio frequency identification tags is described. The system uses at least one set of radio frequency identification tags. Each tag is attached to a container and includes several sensors for detecting physical conditions of said container. The system includes at least one autonomous intermediate reader in wireless communication with the frequency identification tags. The intermediate reader includes external wireless communication system, intermediate reader logic controller, and a self-contained rechargeable power supply. The system uses a central status reporting system in communication the intermediate reader.

  16. Temporal characteristic analysis of laser-modulated pulsed X-ray source for space X-ray communication

    Hang, Shuang; Liu, Yunpeng; Li, Huan; Tang, Xiaobin; Chen, Da

    2018-04-01

    X-ray communication (XCOM) is a new communication type and is expected to realize high-speed data transmission in some special communication scenarios, such as deep space communication and blackout communication. This study proposes a high-speed modulated X-ray source scheme based on the laser-to-X-ray conversion. The temporal characteristics of the essential components of the proposed laser-modulated pulsed X-ray source (LMPXS) were analyzed to evaluate its pulse emission performance. Results show that the LMPXS can provide a maximum modulation rate up to 100 Mbps which is expected to significantly improve the data rate of XCOM.

  17. Creating "communicative spaces": a case of NGO community organizing for HIV/AIDS prevention.

    de Souza, Rebecca

    2009-12-01

    This study uses the case study method to investigate the processes used by a local nongovernmental organization called the Society for People's Action for Development to organize sex workers in the slums of Bangalore, India, for HIV/AIDS prevention. The nongovernmental organization-facilitated HIV/AIDS program is based on the new paradigm of community organizing that encourages community participation and capacity building. Grounded in the culture-centered approach, this study documents the processes used to organize the women, while highlighting the role of communication in these processes. The study identifies 4 primary processes used to mobilize the community, namely collectivization, community awareness and sensitization, capacity building, and providing legal education and support. Each of these processes highlights the importance of attending to the economic, social, and political realities that shape the health of women. The common thread linking these processes together is the notion of "voice." More specifically, each process serves as a catalyst to produce discursive practices that enable women to provide support to each other, increase awareness in the community about the problems that they face, build self-reliance through financial skills training and communication training, and defend their legal rights. In addition, the study suggests that the primary role of nongovernmental organizations should be the creation of "communicative spaces," which are discursive and material spaces within marginalized communities and mainstream society where cultural participants can identify problems (oftentimes beyond the realm of health), manage solutions to those problems, and advocate for health and social change.

  18. Communication Research in Aviation and Space Operations: Symptoms and Strategies of Crew Coordination

    Kanki, Barbara G.; Hart, Sandra G. (Technical Monitor)

    1994-01-01

    implicated in accidents and incidents. NASA/Ames Crew Factors researchers have been developing a model of effective crew coordination in order to understand the sources of performance breakdowns, and to develop effective solutions and interventions. Because communication is a primary mechanism by which information is received and transmitted, and because it is observable behavior, we focus on these group processes in order to identify patterns of communication that distinguish effective from less effective crew performance. Since a prime objective is to develop training recommendations for enhancing communication skills, we interpret our findings in the context of relevant task and environmental conditions, role and procedural constraints, and the normal real-time parameters of flight operations. Another research objective is to consider how communication and coordination can be enhanced through design. For example, flight deck and hardware design as well as procedural and software design may greatly influence the efficiency with which crews communicate and coordinate their work. In addition, teams and tasks may be designed, organized, and trained so that team interactions with each other are based upon appropriately shared knowledge, procedures and situation awareness. In short, we are interested in enhancing communication practices through (1) the training of specific communication skills, and (2) the design of equipment, tasks, procedures, and teams that optimize smooth, unambiguous communication processes. Two examples of communication research will be described; one in aviation and one in space operations. The first example is a high-fidelity full mission simulation study which investigates the affect of flightdeck automation on crew coordination and communication (contrasting crew performance in the DC-9 vs. MD88). Additional information is contained in the original extended abstract.

  19. LEO-to-ground optical communications using SOTA (Small Optical TrAnsponder) - Payload verification results and experiments on space quantum communications

    Carrasco-Casado, Alberto; Takenaka, Hideki; Kolev, Dimitar; Munemasa, Yasushi; Kunimori, Hiroo; Suzuki, Kenji; Fuse, Tetsuharu; Kubo-Oka, Toshihiro; Akioka, Maki; Koyama, Yoshisada; Toyoshima, Morio

    2017-10-01

    Free-space optical communications have held the promise of revolutionizing space communications for a long time. The benefits of increasing the bitrate while reducing the volume, mass and energy of the space terminals have attracted the attention of many researchers for a long time. In the last few years, more and more technology demonstrations have been taking place with participants from both the public and the private sector. The National Institute of Information and Communications Technology (NICT) in Japan has a long experience in this field. SOTA (Small Optical TrAnsponder) was the last NICT space lasercom mission, designed to demonstrate the potential of this technology applied to microsatellites. Since the beginning of SOTA mission in 2014, NICT regularly established communication using the Optical Ground Stations (OGS) located in the Headquarters at Koganei (Tokyo) to receive the SOTA signals, with over one hundred successful links. All the goals of the SOTA mission were fulfilled, including up to 10-Mbit/s downlinks using two different wavelengths and apertures, coarse and fine tracking of the OGS beacon, space-to-ground transmission of the on-board-camera images, experiments with different error correcting codes, interoperability with other international OGS, and experiments on quantum communications. The SOTA mission ended on November 2016, more than doubling the designed lifetime of 1-year. In this paper, the SOTA characteristics and basic operation are explained, along with the most relevant technological demonstrations.

  20. Effective use of multibeam antenna and space-time multiple access technology in modern mobile communication systems

    Moskalets, N. V.

    2015-01-01

    A possibility for efficient use of radio-frequency spectrum and of corresponding increase in productivity of mobile communication system with space-time multiple access obtained by use of multibeam antenna of base station is considered.

  1. Free-Space Optical Communications Link at 1550-nm using Multiple-Quantum-Well Modulating Retroreflectors in a Marine Environment

    Rabinovich, W. S; Mahon, R; Burris, H. R; Gilbreath, G. C; Goetz, P. G; Moore, C. I; Stell, M. F; Vilcheck, M. J; Witkowsky, J. L; Swingen, L

    2005-01-01

    A 1550-nm eye-safe, free-space optical communications link is demonstrated at rates up to 5 Mbits/s over a distance of 2 km in the Chesapeake Bay, using quantum-well-based modulating retroreflectors...

  2. High Precision Ranging and Range-Rate Measurements over Free-Space-Laser Communication Link

    Yang, Guangning; Lu, Wei; Krainak, Michael; Sun, Xiaoli

    2016-01-01

    We present a high-precision ranging and range-rate measurement system via an optical-ranging or combined ranging-communication link. A complete bench-top optical communication system was built. It included a ground terminal and a space terminal. Ranging and range rate tests were conducted in two configurations. In the communication configuration with 622 data rate, we achieved a two-way range-rate error of 2 microns/s, or a modified Allan deviation of 9 x 10 (exp -15) with 10 second averaging time. Ranging and range-rate as a function of Bit Error Rate of the communication link is reported. They are not sensitive to the link error rate. In the single-frequency amplitude modulation mode, we report a two-way range rate error of 0.8 microns/s, or a modified Allan deviation of 2.6 x 10 (exp -15) with 10 second averaging time. We identified the major noise sources in the current system as the transmitter modulation injected noise and receiver electronics generated noise. A new improved system will be constructed to further improve the system performance for both operating modes.

  3. Arms applied to the communications system at the Kourou space centre

    Gerez Martin, L.; Garcia de la Sen, R.

    1993-01-01

    The REMUS (Roseau d'Entreprise MUltiService) has been designed to cover present and future communications needs which are associated with daily operation of the Guyanese Space Centre (GSC). This communications network will facilitate data exchange, contain the data (RSD) and voice network, and paging (RRP), convoy (RCV) and telephony (RSV) systems. The main objectives of the study were: 1. To assess system availability. 2. To dimension spare parts of the renewal equipment and define the logistic delays to be observed in order to achieve an availability target of: - 99.9% for the RRP, RCV and RSV networks. - 99.9% for the RSD network. The RAMSES program developed by Empresarios Agrupados was used in these calculations, to evaluate system behaviour by means of a Monte Carlo simulation. (author)

  4. System and method that suppresses intensity fluctuations for free space high-speed optical communication

    Berman, Gennady P [Los Alamos, NM; Bishop, Alan R [Los Alamos, NM; Nguyen, Dinh C [Los Alamos, NM; Chernobrod, Boris M [Santa Fe, NM; Gorshkov, Vacheslav N [Kiev, UA

    2009-10-13

    A high-speed (Gbps), free space optical communication system is based on spectral encoding of radiation from a wide band light source, such as a laser. By using partially coherent laser beams in combination with a relatively slow photosensor, scintillations can be suppressed by orders of magnitude for distances of more than 10 km. To suppress the intensity fluctuations due to atmospheric turbulence, a source with partial transverse coherence in combination with slow response time photodetector is used. Information is encoded in the spectral domain of a wideband optical source by modulation of spectral amplitudes. A non-coherent light source with wide spectrum (an LED, for example) may be used for high-speed communication over short (less than about a mile) distances.

  5. A multi-rate DPSK modem for free-space laser communications

    Spellmeyer, N. W.; Browne, C. A.; Caplan, D. O.; Carney, J. J.; Chavez, M. L.; Fletcher, A. S.; Fitzgerald, J. J.; Kaminsky, R. D.; Lund, G.; Hamilton, S. A.; Magliocco, R. J.; Mikulina, O. V.; Murphy, R. J.; Rao, H. G.; Scheinbart, M. S.; Seaver, M. M.; Wang, J. P.

    2014-03-01

    The multi-rate DPSK format, which enables efficient free-space laser communications over a wide range of data rates, is finding applications in NASA's Laser Communications Relay Demonstration. We discuss the design and testing of an efficient and robust multi-rate DPSK modem, including aspects of the electrical, mechanical, thermal, and optical design. The modem includes an optically preamplified receiver, an 0.5-W average power transmitter, a LEON3 rad-hard microcontroller that provides the command and telemetry interface and supervisory control, and a Xilinx Virtex-5 radhard reprogrammable FPGA that both supports the high-speed data flow to and from the modem and controls the modem's analog and digital subsystems. For additional flexibility, the transmitter and receiver can be configured to support operation with multi-rate PPM waveforms.

  6. Quantum information processing and communication : Strategic report on current status, visions and goals for research in Europe

    Kouwenhoven, L.; Mooij, J.E.

    2005-01-01

    e present an excerpt of the document “Quantum Information Processing and Communication: Strategic report on current status, visions and goals for research in Europe”, which has been recently published in electronic form at the website of FET (the Future and Emerging Technologies Unit of the

  7. Water Status Related Root-to-Shoot Communication Regulates the Chilling Tolerance of Shoot in Cucumber (Cucumis sativus L.) Plants.

    Zhang, Zi-Shan; Liu, Mei-Jun; Gao, Hui-Yuan; Jin, Li-Qiao; Li, Yu-Ting; Li, Qing-Ming; Ai, Xi-Zhen

    2015-10-16

    Although root-to-shoot communication has been intensively investigated in plants under drought, few studies have examined root-to-shoot communication under chilling. Here we explored whether root-to-shoot communication contributes to the chilling-light tolerance of cucumber shoots and clarified the key signal involves in this communication. After leaf discs chilling-light treatment, the photoinhibitions of Photosystem I (PSI) and Photosystem II (PSII) were similar in leaf discs of two cucumber varieties (JY-3 and JC-4). When the whole plants, including roots, were chilled under light, the photosynthetic performances in JC-4 leaves decreased more seriously than that in JY-3 leaves. However, when the water status of leaves was maintained by warming roots or floating the attached leaves on water, the PSII activity and amount of PSI in the leaves of the two varieties were similar after chilling-light treatment. In addition, the differences of PSII activities and amount of PSI between the two varieties under whole plant chilling-light treatment were independent of ABA pretreatment. Above results indicate that (1) the better water status in leaves under chilling contributes to the higher chilling tolerance of JY-3; (2) the water status, rather than an ABA signal, dominates root-to-shoot communication under chilling and the chilling tolerance of cucumber shoot.

  8. Multi-Objective Reinforcement Learning-Based Deep Neural Networks for Cognitive Space Communications

    Ferreria, Paulo Victor R.; Paffenroth, Randy; Wyglinski, Alexander M.; Hackett, Timothy M.; Bilen, Sven G.; Reinhart, Richard C.; Mortensen, Dale J.

    2017-01-01

    Future communication subsystems of space exploration missions can potentially benefit from software-defined radios (SDRs) controlled by machine learning algorithms. In this paper, we propose a novel hybrid radio resource allocation management control algorithm that integrates multi-objective reinforcement learning and deep artificial neural networks. The objective is to efficiently manage communications system resources by monitoring performance functions with common dependent variables that result in conflicting goals. The uncertainty in the performance of thousands of different possible combinations of radio parameters makes the trade-off between exploration and exploitation in reinforcement learning (RL) much more challenging for future critical space-based missions. Thus, the system should spend as little time as possible on exploring actions, and whenever it explores an action, it should perform at acceptable levels most of the time. The proposed approach enables on-line learning by interactions with the environment and restricts poor resource allocation performance through virtual environment exploration. Improvements in the multiobjective performance can be achieved via transmitter parameter adaptation on a packet-basis, with poorly predicted performance promptly resulting in rejected decisions. Simulations presented in this work considered the DVB-S2 standard adaptive transmitter parameters and additional ones expected to be present in future adaptive radio systems. Performance results are provided by analysis of the proposed hybrid algorithm when operating across a satellite communication channel from Earth to GEO orbit during clear sky conditions. The proposed approach constitutes part of the core cognitive engine proof-of-concept to be delivered to the NASA Glenn Research Center SCaN Testbed located onboard the International Space Station.

  9. Passive Thermal Design Approach for the Space Communications and Navigation (SCaN) Testbed Experiment on the International Space Station (ISS)

    Siamidis, John; Yuko, Jim

    2014-01-01

    The Space Communications and Navigation (SCaN) Program Office at NASA Headquarters oversees all of NASAs space communications activities. SCaN manages and directs the ground-based facilities and services provided by the Deep Space Network (DSN), Near Earth Network (NEN), and the Space Network (SN). Through the SCaN Program Office, NASA GRC developed a Software Defined Radio (SDR) testbed experiment (SCaN testbed experiment) for use on the International Space Station (ISS). It is comprised of three different SDR radios, the Jet Propulsion Laboratory (JPL) radio, Harris Corporation radio, and the General Dynamics Corporation radio. The SCaN testbed experiment provides an on-orbit, adaptable, SDR Space Telecommunications Radio System (STRS) - based facility to conduct a suite of experiments to advance the Software Defined Radio, Space Telecommunications Radio Systems (STRS) standards, reduce risk (Technology Readiness Level (TRL) advancement) for candidate Constellation future space flight hardware software, and demonstrate space communication links critical to future NASA exploration missions. The SCaN testbed project provides NASA, industry, other Government agencies, and academic partners the opportunity to develop and field communications, navigation, and networking technologies in the laboratory and space environment based on reconfigurable, software defined radio platforms and the STRS Architecture.The SCaN testbed is resident on the P3 Express Logistics Carrier (ELC) on the exterior truss of the International Space Station (ISS). The SCaN testbed payload launched on the Japanese Aerospace Exploration Agency (JAXA) H-II Transfer Vehicle (HTV) and was installed on the ISS P3 ELC located on the inboard RAM P3 site. The daily operations and testing are managed out of NASA GRC in the Telescience Support Center (TSC).

  10. U.S. Materials Science on the International Space Station: Status and Plans

    Chiaramonte, Francis P.; Kelton, Kenneth F.; Matson, Douglas M.; Poirier, David R.; Trivedi, Rohit K.; Su, Ching-Hua; Volz, Martin P.; Voorhees, Peter W.

    2010-01-01

    This viewgraph presentation reviews the current status and NASA plans for materials science on the International Space Station. The contents include: 1) Investigations Launched in 2009; 2) DECLIC in an EXPRESS rack; 3) Dynamical Selection of Three-Dimensional Interface Patterns in Directional Solidification (DSIP); 4) Materials Science Research Rack (MSRR); 5) Materials Science Laboratory; 6) Comparison of Structure and Segregation in Alloys Directionally Solidified in Terrestrial and Microgravity Environments (MICAST/CETSOL); 7) Coarsening in Solid Liquid Mixtures 2 Reflight (CSLM 2R); 8) Crystal Growth Investigations; 9) Levitator Investigations; 10) Quasi Crystalline Undercooled Alloys for Space Investigation (QUASI); 11) The Role of Convection and Growth Competition in Phase Selection in Microgravity (LODESTARS); 12) Planned Additional Investigations; 13) SETA; 14) METCOMP; and 15) Materials Science NRA.

  11. Space communication system for compressed data with a concatenated Reed-Solomon-Viterbi coding channel

    Rice, R. F.; Hilbert, E. E. (Inventor)

    1976-01-01

    A space communication system incorporating a concatenated Reed Solomon Viterbi coding channel is discussed for transmitting compressed and uncompressed data from a spacecraft to a data processing center on Earth. Imaging (and other) data are first compressed into source blocks which are then coded by a Reed Solomon coder and interleaver, followed by a convolutional encoder. The received data is first decoded by a Viterbi decoder, followed by a Reed Solomon decoder and deinterleaver. The output of the latter is then decompressed, based on the compression criteria used in compressing the data in the spacecraft. The decompressed data is processed to reconstruct an approximation of the original data-producing condition or images.

  12. On the performance of free-space optical communication systems with multiuser diversity

    Yang, Liang

    2014-09-01

    Free space optical (FSO) communication has become a cost-effective method to provide high data rates. However, the turbulence-induced fading limits its application to short range applications. To address this, we propose a multiuser diversity (MD) FSO scheme in which the Nth best user is selected and the channel fluctuations can be effectively exploited to produce a selection diversity gain. More specifically, we first present the statistics analysis for the considered system over weak atmospheric turbulence channels. Based on these statistics, the outage probability, bit-error rate performance, and coverage are analyzed.

  13. Free Space Laser Communication Experiments from Earth to the Lunar Reconnaissance Orbiter in Lunar Orbit

    Sun, Xiaoli; Skillman, David R.; Hoffman, Evan D.; Mao, Dandan; McGarry, Jan F.; Zellar, Ronald S.; Fong, Wai H; Krainak, Michael A.; Neumann, Gregory A.; Smith, David E.

    2013-01-01

    Laser communication and ranging experiments were successfully conducted from the satellite laser ranging (SLR) station at NASA Goddard Space Flight Center (GSFC) to the Lunar Reconnaissance Orbiter (LRO) in lunar orbit. The experiments used 4096-ary pulse position modulation (PPM) for the laser pulses during one-way LRO Laser Ranging (LR) operations. Reed-Solomon forward error correction codes were used to correct the PPM symbol errors due to atmosphere turbulence and pointing jitter. The signal fading was measured and the results were compared to the model.

  14. Integration of communications and tracking data processing simulation for space station

    Lacovara, Robert C.

    1987-01-01

    A simplified model of the communications network for the Communications and Tracking Data Processing System (CTDP) was developed. It was simulated by use of programs running on several on-site computers. These programs communicate with one another by means of both local area networks and direct serial connections. The domain of the model and its simulation is from Orbital Replaceable Unit (ORU) interface to Data Management Systems (DMS). The simulation was designed to allow status queries from remote entities across the DMS networks to be propagated through the model to several simulated ORU's. The ORU response is then propagated back to the remote entity which originated the request. Response times at the various levels were investigated in a multi-tasking, multi-user operating system environment. Results indicate that the effective bandwidth of the system may be too low to support expected data volume requirements under conventional operating systems. Instead, some form of embedded process control program may be required on the node computers.

  15. Patent and exclusivity status of essential medicines for non-communicable disease.

    Tim K Mackey

    Full Text Available OBJECTIVE: The threat of non-communicable diseases ("NCDs" is increasingly becoming a global health crisis and are pervasive in high, middle, and low-income populations resulting in an estimated 36 million deaths per year. There is a need to assess intellectual property rights ("IPRs" that may impede generic production and availability and affordability to essential NCD medicines. METHODS: Using the data sources listed below, the study design systematically eliminated NCD drugs that had no patent/exclusivity provisions on API, dosage, or administration route. The first step identified essential medicines that treat certain high disease burden NCDs. A second step examined the patent and exclusivity status of active ingredient, dosage and listed route of administration using exclusion criteria outlined in this study. MATERIALS: We examined the patent and exclusivity status of medicines listed in the World Health Organization's ("WHO" Model List of Essential Drugs (Medicines ("MLEM" and other WHO sources for drugs treating certain NCDs. i.e., cardiovascular and respiratory disease, cancers, and diabetes. We utilized the USA Food and Drug Administration Orange Book and the USA Patent and Trademark Office databases as references given the predominant number of medicines registered in the USA. RESULTS: Of the 359 MLEM medicines identified, 22% (79/359 address targeted NCDs. Of these 79, only eight required in-depth patent or exclusivity assessment. Upon further review, no NCD MLEM medicines had study patent or exclusivity protection for reviewed criteria. CONCLUSIONS: We find that ensuring availability and affordability of potential generic formulations of NCD MLEM medicines appears to be more complex than the presence of IPRs with API, dosage, or administration patent or exclusivity protection. Hence, more sophisticated analysis of NCD barriers to generic availability and affordability should be conducted in order to ensure equitable access to global

  16. Inequality, green spaces, and pregnant women: roles of ethnicity and individual and neighbourhood socioeconomic status.

    Dadvand, Payam; Wright, John; Martinez, David; Basagaña, Xavier; McEachan, Rosemary R C; Cirach, Marta; Gidlow, Christopher J; de Hoogh, Kees; Gražulevičienė, Regina; Nieuwenhuijsen, Mark J

    2014-10-01

    Evidence of the impact of green spaces on pregnancy outcomes is limited with no report on how this impact might vary by ethnicity. We investigated the association between residential surrounding greenness and proximity to green spaces and birth weight and explored the modification of this association by ethnicity and indicators of individual (maternal education) and neighbourhood (Index of Multiple Deprivation) socioeconomic status. Our study was based on 10,780 singleton live-births from the Born in Bradford cohort, UK (2007-2010). We defined residential surrounding greenness as average of satellite-based Normalized Difference Vegetation Index (NDVI) in buffers of 50 m, 100 m, 250 m, 500 m and 1000 m around each maternal home address. Residential proximity to green spaces was defined as living within 300 m of a green space with an area of ≥ 5000 m(2). We utilized mixed effects models to estimate adjusted change in birth weight associated with residential surrounding greenness as well as proximity to green spaces. We found a positive association between birth weight and residential surrounding greenness. Furthermore, we observed an interaction between ethnicity and residential surrounding greenness in that for White British participants there was a positive association between birth weight and residential surrounding greenness whereas for participants of Pakistani origin there was no such an association. For surrounding greenness in larger buffers (500 m and 1000 m) there were some indications of stronger associations for participants with lower education and those living in more deprived neighbourhoods which were not replicated for surrounding greenness in smaller buffer sizes (i.e. 50 m, 100 m, and 250 m). The findings for residential proximity to a green space were not conclusive. Our study showed that residential surrounding greenness is associated with better foetal growth and this association could vary between different ethnic and socioeconomic groups

  17. Influence of wind speed on free space optical communication performance for Gaussian beam propagation through non Kolmogorov strong turbulence

    Deng Peng; Yuan Xiuhua; Zeng Yanan; Zhao Ming; Luo Hanjun

    2011-01-01

    In free-space optical communication links, atmospheric turbulence causes fluctuations in both the intensity and the phase of the received signal, affecting link performance. Most theoretical treatments have been described by Kolmogorov's power spectral density model through weak turbulence with constant wind speed. However, several experiments showed that Kolmogorov theory is sometimes incomplete to describe atmospheric turbulence properly, especially through the strong turbulence with variable wind speed, which is known to contribute significantly to the turbulence in the atmosphere. We present an optical turbulence model that incorporates into variable wind speed instead of constant value, a non-Kolmogorov power spectrum that uses a generalized exponent instead of constant standard exponent value 11/3, and a generalized amplitude factor instead of constant value 0.033. The free space optical communication performance for a Gaussian beam wave of scintillation index, mean signal-to-noise ratio , and mean bit error rate , have been derived by extended Rytov theory in non-Kolmogorov strong turbulence. And then the influence of wind speed variations on free space optical communication performance has been analyzed under different atmospheric turbulence intensities. The results suggest that the effects of wind speed variation through non-Kolmogorov turbulence on communication performance are more severe in many situations and need to be taken into account in free space optical communication. It is anticipated that this work is helpful to the investigations of free space optical communication performance considering wind speed under severe weather condition in the strong atmospheric turbulence.

  18. Communicating Conservation Status: How Different Statistical Assessment Criteria Affect Perceptions of Extinction Risk.

    Song, Hwanseok; Schuldt, Jonathon P

    2017-09-01

    Although alternative forms of statistical and verbal information are routinely used to convey species' extinction risk to policymakers and the public, little is known about their effects on audience information processing and risk perceptions. To address this gap in literature, we report on an experiment that was designed to explore how perceptions of extinction risk differ as a function of five different assessment benchmarks (Criteria A-E) used by scientists to classify species within IUCN Red List risk levels (e.g., Critically Endangered, Vulnerable), as well as the role of key individual differences in these effects (e.g., rational and experiential thinking styles, environmental concern). Despite their normative equivalence within the IUCN classification system, results revealed divergent effects of specific assessment criteria: on average, describing extinction risk in terms of proportional population decline over time (Criterion A) and number of remaining individuals (Criterion D) evoked the highest level of perceived risk, whereas the single-event probability of a species becoming extinct (Criterion E) engendered the least perceived risk. Furthermore, participants scoring high in rationality (analytic thinking) were less prone to exhibit these biases compared to those low in rationality. Our findings suggest that despite their equivalence in the eyes of scientific experts, IUCN criteria are indeed capable of engendering different levels of risk perception among lay audiences, effects that carry direct and important implications for those tasked with communicating about conservation status to diverse publics. © 2016 Society for Risk Analysis.

  19. Dember effect photodetectors and the effects of turbulence on free-space optical communication systems

    Dikmelik, Yamac

    High-speed free-space optical communication systems have recently utilized components that have been developed for fiber-optic communication systems. The received laser beam in such a system must be coupled into a single-mode fiber at the input of a commercially available receiver module or a wavelength division demultiplexer. However, one effect of propagation through atmospheric turbulence is that the spatial coherence of a laser beam is degraded and the percentage of the available power that can be coupled into the single-mode fiber is limited. This dissertation presents a numerical evaluation of fiber coupling efficiency for laser light distorted by atmospheric turbulence. The results for weak fluctuation conditions provide the level of coupling efficiency that can be expected for a given turbulence strength. In addition, the results show that the link distance must be limited to 400 m under moderate turbulence conditions if the link budget requires a coupling efficiency of 0.1. We also investigate the use of a coherent fiber array as a receiver structure to improve the fiber coupling efficiency of a free-space optical communication system. Our numerical results show that a coherent fiber array that consists of seven subapertures would increase fiber coupling efficiency by a significant amount for representative turbulence conditions and link distances. The use of photo-emf detectors as elements of a wavefront sensor for an adaptive optics system is also considered as an alternative method of reducing the effects of turbulence on a free-space optical communication system. Dember and photo-emf currents are investigated in silicon photoconductive detectors both theoretically and experimentally. Our results show that Dember photocurrents dominate the response of high-purity silicon samples with top surface electrodes to a moving interference pattern. The use of surface electrodes leads to shadowed regions beneath the electrodes and Dember photocurrents appear

  20. Analysis of large optical ground stations for deep-space optical communications

    Garcia-Talavera, M. Reyes; Rivera, C.; Murga, G.; Montilla, I.; Alonso, A.

    2017-11-01

    Inter-satellite and ground to satellite optical communications have been successfully demonstrated over more than a decade with several experiments, the most recent being NASA's lunar mission Lunar Atmospheric Dust Environment Explorer (LADEE). The technology is in a mature stage that allows to consider optical communications as a high-capacity solution for future deep-space communications [1][2], where there is an increasing demand on downlink data rate to improve science return. To serve these deep-space missions, suitable optical ground stations (OGS) have to be developed providing large collecting areas. The design of such OGSs must face both technical and cost constraints in order to achieve an optimum implementation. To that end, different approaches have already been proposed and analyzed, namely, a large telescope based on a segmented primary mirror, telescope arrays, and even the combination of RF and optical receivers in modified versions of existing Deep-Space Network (DSN) antennas [3][4][5]. Array architectures have been proposed to relax some requirements, acting as one of the key drivers of the present study. The advantages offered by the array approach are attained at the expense of adding subsystems. Critical issues identified for each implementation include their inherent efficiency and losses, as well as its performance under high-background conditions, and the acquisition, pointing, tracking, and synchronization capabilities. It is worth noticing that, due to the photon-counting nature of detection, the system performance is not solely given by the signal-to-noise ratio parameter. To start with the analysis, first the main implications of the deep space scenarios are summarized, since they are the driving requirements to establish the technical specifications for the large OGS. Next, both the main characteristics of the OGS and the potential configuration approaches are presented, getting deeper in key subsystems with strong impact in the

  1. Nutritional status assessment in semiclosed environments: ground-based and space flight studies in humans

    Smith, S. M.; Davis-Street, J. E.; Rice, B. L.; Nillen, J. L.; Gillman, P. L.; Block, G.

    2001-01-01

    Adequate nutrition is critical during long-term spaceflight, as is the ability to easily monitor dietary intake. A comprehensive nutritional status assessment profile was designed for use before, during and after flight. It included assessment of both dietary intake and biochemical markers of nutritional status. A spaceflight food-frequency questionnaire (FFQ) was developed to evaluate intake of key nutrients during spaceflight. The nutritional status assessment protocol was evaluated during two ground-based closed-chamber studies (60 and 91 d; n = 4/study), and was implemented for two astronauts during 4-mo stays on the Mir space station. Ground-based studies indicated that the FFQ, administered daily or weekly, adequately estimated intake of key nutrients. Chamber subjects maintained prechamber energy intake and body weight. Astronauts tended to eat 40--50% of WHO-predicted energy requirements, and lost >10% of preflight body mass. Serum ferritin levels were lower after the chamber stays, despite adequate iron intake. Red blood cell folate concentrations were increased after the chamber studies. Vitamin D stores were decreased by > 40% on chamber egress and after spaceflight. Mir crew members had decreased levels of most nutritional indices, but these are difficult to interpret given the insufficient energy intake and loss of body mass. Spaceflight food systems can provide adequate intake of macronutrients, although, as expected, micronutrient intake is a concern for any closed or semiclosed food system. These data demonstrate the utility and importance of nutritional status assessment during spaceflight and of the FFQ during extended-duration spaceflight.

  2. A Status of the Advanced Space Transportation Program from Planning to Action

    Lyles, Garry; Griner, Carolyn

    1998-01-01

    A Technology Plan for Enabling Commercial Space Business was presented at the 48th International Astronautical Congress in Turin, Italy. This paper presents a status of the program's accomplishments. Technology demonstrations have progressed in each of the four elements of the program; (1) Low Cost Technology, (2) Advanced Reusable Technology, (3) Space Transfer Technology and (4) Space Transportation Research. The Low Cost Technology program element is primarily focused at reducing development and acquisition costs of aerospace hardware using a "design to cost" philosophy with robust margins, adapting commercial manufacturing processes and commercial off-the-shelf hardware. The attributes of this philosophy for small payload launch are being demonstrated at the component, sub-system, and system level. The X-34 "Fastrac" engine has progressed through major component and subsystem demonstrations. A propulsion system test bed has been implemented for system-level demonstration of component and subsystem technologies; including propellant tankage and feedlines, controls, pressurization, and engine systems. Low cost turbopump designs, commercial valves and a controller are demonstrating the potential for a ten-fold reduction in engine and propulsion system costs. The Advanced Reusable Technology program element is focused on increasing life through high strength-to-weight structures and propulsion components, highly integrated propellant tanks, automated checkout and health management and increased propulsion system performance. The validation of rocket based combined cycle (RBCC) propulsion is pro,-,ressing through component and subsystem testing. RBCC propulsion has the potential to provide performance margin over an all rocket system that could result in lower gross liftoff weight, a lower propellant mass fraction or a higher payload mass fraction. The Space Transfer Technology element of the program is pursuing technology that can improve performance and

  3. The status of lightweight photovoltaic space array technology based on amorphous silicon solar cells

    Hanak, Joseph J.; Kaschmitter, Jim

    1991-01-01

    Ultralight, flexible photovoltaic (PV) array of amorphous silicon (a-Si) was identified as a potential low cost power source for small satellites. A survey was conducted of the status of the a-Si PV array technology with respect to present and future performance, availability, cost, and risks. For existing, experimental array blankets made of commercial cell material, utilizing metal foil substrates, the Beginning of Life (BOL) performance at Air Mass Zero (AM0) and 35 C includes total power up to 200 W, power per area of 64 W/sq m and power per weight of 258 W/kg. Doubling of power per weight occurs when polyimide substrates are used. Estimated End of Life (EOL) power output after 10 years in a nominal low earth orbit would be 80 pct. of BOL, the degradation being due to largely light induced effects (-10 to -15 pct.) and in part (-5 pct.) to space radiation. Predictions for the year 1995 for flexible PV arrays, made on the basis of published results for rigid a-Si modules, indicate EOL power output per area and per weight of 105 W/sq m and 400 W/kg, respectively, while predictions for the late 1990s based on existing U.S. national PV program goals indicate EOL values of 157 W/sq m and 600 W/kg. Cost estimates by vendors for 200 W ultralight arrays in volume of over 1000 units range from $100/watt to $125/watt. Identified risks include the lack of flexible, space compatible encapsulant, the lack of space qualification effort, recent partial or full acquisitions of US manufacturers of a-Si cells by foreign firms, and the absence of a national commitment for a long range development program toward developing of this important power source for space.

  4. Enabling Future Science and Human Exploration with NASA's Next Generation Near Earth and Deep Space Communications and Navigation Architecture

    Reinhart, Richard; Schier, James; Israel, David; Tai, Wallace; Liebrecht, Philip; Townes, Stephen

    2017-01-01

    The National Aeronautics and Space Administration (NASA) is studying alternatives for the United States space communications architecture through the 2040 timeframe. This architecture provides communication and navigation services to both human exploration and science missions throughout the solar system. Several of NASA's key space assets are approaching their end of design life and major systems are in need of replacement. The changes envisioned in the relay satellite architecture and capabilities around both Earth and Mars are significant undertakings and occur only once or twice each generation, and therefore is referred to as NASA's next generation space communications architecture. NASA's next generation architecture will benefit from technology and services developed over recent years. These innovations will provide missions with new operations concepts, increased performance, and new business and operating models. Advancements in optical communications will enable high-speed data channels and the use of new and more complex science instruments. Modern multiple beam/multiple access technologies such as those employed on commercial high throughput satellites will enable enhanced capabilities for on-demand service, and with new protocols will help provide Internet-like connectivity for cooperative spacecraft to improve data return and coordinate joint mission objectives. On-board processing with autonomous and cognitive networking will play larger roles to help manage system complexity. Spacecraft and ground systems will coordinate among themselves to establish communications, negotiate link connectivity, and learn to share spectrum to optimize resource allocation. Spacecraft will autonomously navigate, plan trajectories, and handle off-nominal events. NASA intends to leverage the ever-expanding capabilities of the satellite communications industry and foster its continued growth. NASA's technology development will complement and extend commercial capabilities

  5. Enabling Future Science and Human Exploration with NASA's Next Generation near Earth and Deep Space Communications and Navigation Architecture

    Reinhart, Richard C.; Schier, James S.; Israel, David J.; Tai, Wallace; Liebrecht, Philip E.; Townes, Stephen A.

    2017-01-01

    The National Aeronautics and Space Administration (NASA) is studying alternatives for the United States space communications architecture through the 2040 timeframe. This architecture provides communication and navigation services to both human exploration and science missions throughout the solar system. Several of NASA's key space assets are approaching their end of design life and major systems are in need of replacement. The changes envisioned in the relay satellite architecture and capabilities around both Earth and Mars are significant undertakings and occur only once or twice each generation, and therefore is referred to as NASA's next generation space communications architecture. NASA's next generation architecture will benefit from technology and services developed over recent years. These innovations will provide missions with new operations concepts, increased performance, and new business and operating models. Advancements in optical communications will enable high-speed data channels and the use of new and more complex science instruments. Modern multiple beam/multiple access technologies such as those employed on commercial high throughput satellites will enable enhanced capabilities for on-demand service, and with new protocols will help provide Internet-like connectivity for cooperative spacecraft to improve data return and coordinate joint mission objectives. On-board processing with autonomous and cognitive networking will play larger roles to help manage system complexity. Spacecraft and ground systems will coordinate among themselves to establish communications, negotiate link connectivity, and learn to share spectrum to optimize resource allocation. Spacecraft will autonomously navigate, plan trajectories, and handle off-nominal events. NASA intends to leverage the ever-expanding capabilities of the satellite communications industry and foster its continued growth. NASA's technology development will complement and extend commercial capabilities

  6. English language status and English communication in culturally diverse academic departments

    Selmer, Jan; Lauring, Jakob

    2011-01-01

    universities, results showed that English fluency had a positive association with inter-individual communication and management communication, both in English, while linguistic distance only had a positive relationship with inter-individual communication in English. Implications of these findings are discussed...

  7. Cell-to-cell communication and cellular environment alter the somatostatin status of delta cells

    Kelly, Catriona, E-mail: catriona.kelly@qub.ac.uk [SAAD Centre for Pharmacy and Diabetes, School of Biomedical Sciences, University of Ulster, Coleraine (United Kingdom); Flatt, Peter R.; McClenaghan, Neville H. [SAAD Centre for Pharmacy and Diabetes, School of Biomedical Sciences, University of Ulster, Coleraine (United Kingdom)

    2010-08-20

    Research highlights: {yields} TGP52 cells display enhanced functionality in pseudoislet form. {yields} Somatostatin content was reduced, but secretion increased in high glucose conditions. {yields} Cellular interactions and environment alter the somatostatin status of TGP52 cells. -- Abstract: Introduction: Somatostatin, released from pancreatic delta cells, is a potent paracrine inhibitor of insulin and glucagon secretion. Islet cellular interactions and glucose homeostasis are essential to maintain normal patterns of insulin secretion. However, the importance of cell-to-cell communication and cellular environment in the regulation of somatostatin release remains unclear. Methods: This study employed the somatostatin-secreting TGP52 cell line maintained in DMEM:F12 (17.5 mM glucose) or DMEM (25 mM glucose) culture media. The effect of pseudoislet formation and culture medium on somatostatin content and release in response to a variety of stimuli was measured by somatostatin EIA. In addition, the effect of pseudoislet formation on cellular viability (MTT and LDH assays) and proliferation (BrdU ELISA) was determined. Results: TGP52 cells readily formed pseudoislets and showed enhanced functionality in three-dimensional form with increased E-cadherin expression irrespective of the culture environment used. However, culture in DMEM decreased cellular somatostatin content (P < 0.01) and increased somatostatin secretion in response to a variety of stimuli including arginine, calcium and PMA (P < 0.001) when compared with cells grown in DMEM:F12. Configuration of TGP52 cells as pseudoislets reduced the proliferative rate and increased cellular cytotoxicity irrespective of culture medium used. Conclusions: Somatostatin secretion is greatly facilitated by cell-to-cell interactions and E-cadherin expression. Cellular environment and extracellular glucose also significantly influence the function of delta cells.

  8. Cell-to-cell communication and cellular environment alter the somatostatin status of delta cells

    Kelly, Catriona; Flatt, Peter R.; McClenaghan, Neville H.

    2010-01-01

    Research highlights: → TGP52 cells display enhanced functionality in pseudoislet form. → Somatostatin content was reduced, but secretion increased in high glucose conditions. → Cellular interactions and environment alter the somatostatin status of TGP52 cells. -- Abstract: Introduction: Somatostatin, released from pancreatic delta cells, is a potent paracrine inhibitor of insulin and glucagon secretion. Islet cellular interactions and glucose homeostasis are essential to maintain normal patterns of insulin secretion. However, the importance of cell-to-cell communication and cellular environment in the regulation of somatostatin release remains unclear. Methods: This study employed the somatostatin-secreting TGP52 cell line maintained in DMEM:F12 (17.5 mM glucose) or DMEM (25 mM glucose) culture media. The effect of pseudoislet formation and culture medium on somatostatin content and release in response to a variety of stimuli was measured by somatostatin EIA. In addition, the effect of pseudoislet formation on cellular viability (MTT and LDH assays) and proliferation (BrdU ELISA) was determined. Results: TGP52 cells readily formed pseudoislets and showed enhanced functionality in three-dimensional form with increased E-cadherin expression irrespective of the culture environment used. However, culture in DMEM decreased cellular somatostatin content (P < 0.01) and increased somatostatin secretion in response to a variety of stimuli including arginine, calcium and PMA (P < 0.001) when compared with cells grown in DMEM:F12. Configuration of TGP52 cells as pseudoislets reduced the proliferative rate and increased cellular cytotoxicity irrespective of culture medium used. Conclusions: Somatostatin secretion is greatly facilitated by cell-to-cell interactions and E-cadherin expression. Cellular environment and extracellular glucose also significantly influence the function of delta cells.

  9. An interdisciplinary space of scientific communication in Collective (Public) Health: the journal interface--Communication, Health, Education.

    Cyrino, Antonio Pithon; Lima, Elizabeth Araújo; Garcia, Vera Lucia; Teixeira, Ricardo Rodrigues; Foresti, Miriam Celí Pimentel Porto; Schraiber, Lilia Blima

    2015-07-01

    This is a reflection upon 17 years of experience in the production of an interdisciplinary scientific journal, the publication "Interface: Communication, Health, Education," whose scope is in the fields of Collective (Public) Health, Education and Communication. It also examines retrospectively the themes published by the journal, seeking to identify them in different sections of this publication. Finally, the evolution of the journal is analyzed.

  10. Main-Reflector Manufacturing Technology for the Deep Space Optical Communications Ground Station

    Britcliffe, M. J.; Hoppe, D. J.

    2001-01-01

    The Deep Space Network (DSN) has plans to develop a 10-m-diameter optical communications receiving station. The system uses the direct detection technique, which has much different requirements from a typical astronomical telescope. The receiver must operate in daylight and nighttime conditions. This imposes special requirements on the optical system to reject stray light from the Sun and other sources. One of the biggest challenges is designing a main-reflector surface that meets these requirements and can be produced at a reasonable cost. The requirements for the performance of the reflector are presented. To date, an aspherical primary reflector has been assumed. A reflector with a spherical reflector has a major cost advantage over an aspherical design, with no sacrifice in performance. A survey of current manufacturing techniques for optical mirrors of this type was performed. Techniques including solid glass, lightweight glass, diamond-turned aluminum, and composite mirrors were investigated.

  11. NASA's Evolution to K(sub a)- Band Space Communications for Near-Earth Spacecraft

    McCarthy, Kevin P.; Stocklin, Frank J.; Geldzahler, Barry J.; Friedman, Daniel E.; Celeste, Peter B.

    2010-01-01

    Over the next several years, NASA plans to launch multiple earth-science missions which will send data from low-Earth orbits to ground stations at 1-3 Gbps, to achieve data throughputs of 5-40 terabits per day. These transmission rates exceed the capabilities of S-band and X-band frequency allocations used for science probe downlinks in the past. Accordingly, NASA is exploring enhancements to its space communication capabilities to provide the Agency's first Ka-band architecture solution for next generation missions in the near-earth regime. This paper describes the proposed Ka-band solution's drivers and concept, constraints and analyses which shaped that concept, and expansibility for future needs

  12. Performance analysis of coherent free space optical communications with sequential pyramid wavefront sensor

    Liu, Wei; Yao, Kainan; Chen, Lu; Huang, Danian; Cao, Jingtai; Gu, Haijun

    2018-03-01

    Based-on the previous study on the theory of the sequential pyramid wavefront sensor (SPWFS), in this paper, the SPWFS is first applied to the coherent free space optical communications (FSOC) with more flexible spatial resolution and higher sensitivity than the Shack-Hartmann wavefront sensor, and with higher uniformity of intensity distribution and much simpler than the pyramid wavefront sensor. Then, the mixing efficiency (ME) and the bit error rate (BER) of the coherent FSOC are analyzed during the aberrations correction through numerical simulation with binary phase shift keying (BPSK) modulation. Finally, an experimental AO system based-on SPWFS is setup, and the experimental data is used to analyze the ME and BER of homodyne detection with BPSK modulation. The results show that the AO system based-on SPWFS can increase ME and decrease BER effectively. The conclusions of this paper provide a new method of wavefront sensing for designing the AO system for a coherent FSOC system.

  13. Performance Analysis of Free-Space Optical Communication Systems With Multiuser Diversity Over Atmospheric Turbulence Channels

    Yang, Liang

    2014-04-01

    Free-space optical (FSO) communication has become a cost-effective method to provide high data rates. However, the turbulence-induced fading limits its application to short-range applications. To address this, we propose a multiuser diversity (MD) FSO scheme in which the Nth best user is selected and the channel fluctuations can be effectively exploited to produce a selection diversity gain. More specifically, we first present the statistics analysis for the considered system over both weak and strong atmospheric turbulence channels. Based on these statistics, the outage probability, bit-error rate performance, average capacity, diversity order, and coverage are analyzed. Results show that the diversity order for the gamma-gamma fading is N min{α, β}/2, where N is the number of users, and α and β are the channel fading parameters related to the effective atmospheric conditions of the link.

  14. Hybrid microtransmitter for free-space optical spacecraft communication: design, manufacturing, and characterization

    Lotfi, Sara; Palmer, Kristoffer; Kratz, Henrik; Thornell, Greger

    2009-02-01

    Optical intra-communication links are investigated by several currently operational qualification missions. Compared with RF communication systems, the optical domain obtains a wider bandwidth, enables miniaturized spacecraft and reduced power consumption. In this project, a microtransmitter is designed and manufactured for formation flying spacecraft with transmission rates of 1 Gbit/s. Simulations in Matlab and Simulink show that a BER of 10-9 can be achieved with aperture sizes of 1 cm and a transmitter output peak power of 12 mW for a distance of 10 km. The results show that the performance of the communication link decreases due to mechanical vibrations in the spacecraft together with a narrow laser beam. A dual-axis microactuator designed as a deflectable mirror has been developed for the laser beam steering where the fabrication is based on a double-sided, bulk micromachining process. The mirror actuates by joints consisting of v-grooves filled with SU-8 polymer. The deflection is controlled by integrated resistive heaters in the joints causing the polymer to expand thermally. Results show that the mirror actuates 20-30° in the temperature interval 25-250°C. Flat Fresnel lenses made of Pyrex 7740 are used to collimate the laser beam. These lenses are simulated in the Comsol software and optimized for a 670 nm red VCSEL. The lenses are manufactured using lithography and reactive ion etching. All tests are made in a normal laboratory environment, but the effect of the space environment is discussed.

  15. Analysis of fog effects on terrestrial Free Space optical communication links

    Esmail, Maged Abdullah

    2016-07-26

    In this paper, we consider and examine fog measurement data, coming from several locations in Europe and USA, and attempt to derive a unified model for fog attenuation in free space optics (FSO) communication links. We evaluate and compare the performance of our proposed model to that of many well-known alternative models. We found that our proposed model, achieves an average RMSE that outperforms them by more than 9 dB. Furthermore, we have studied the performance of the FSO system using different performance metrics such as signal-to-noise (SNR) ratio, bit error rate (BER), and channel capacity. Our results show that FSO is a short range technology. Therefore, FSO is expected to find its place in future networks that will have small cell size, i.e., <1 km diameter. Moreover, our investigation shows that under dense fog, it is difficult to maintain a communications link because of the high signal attenuation, which requires switching the communications to RF backup. Our results show that increasing the transmitted power will improve the system performance under light fog. However, under heavy fog, the effect is minor. To enhance the system performance under low visibility range, multi-hop link is used which can enhance the power budget by using short segments links. Using 22 dBm transmitted power, we obtained BER=10-3 over 1 km link length with 600 m visibility range which corresponds to light fog. However, under lower visibility range equals 40 m that corresponds to dense fog, we obtained the same BER but over 200 m link length. © 2016 IEEE.

  16. Status and performance of the CALorimetric Electron Telescope (CALET) on the International Space Station

    Adriani, O. [University of Florence, IFAC (CNR) and INFN (Italy); Akaike, Y. [ICRR, University of Tokyo (Japan); Asaoka, Y. [Waseda University (Japan); Asano, K. [Tokyo Institute of Technology (Japan); Bagliesi, M.G.; Bigongiari, G. [University of Siena and INFN (Italy); Binns, W.R. [Washington University-St. Louis (United States); Bongi, M. [University of Florence, IFAC (CNR) and INFN (Italy); Buckley, J.H. [Washington University-St. Louis (United States); Cassese, A.; Castellini, G. [University of Florence, IFAC (CNR) and INFN (Italy); Cherry, M.L. [Louisiana State University (United States); Collazuol, G. [University of Padova and INFN (Italy); Ebisawa, K. [JAXA/ISAS (Japan); Di Felice, V. [University of Rome Tor Vergata and INFN (Italy); Fuke, H. [JAXA/ISAS (Japan); Guzik, T.G. [Louisiana State University (United States); Hams, T. [CRESST/NASA/GSFC and University of Maryland (United States); Hasebe, N. [Waseda University (Japan); Hareyama, M. [St. Marianna University School of Medicine (Japan); and others

    2014-11-15

    The CALorimetric Electron Telescope (CALET) space experiment, currently under development by Japan in collaboration with Italy and the United States, will measure the flux of cosmic-ray electrons (including positrons) to 20 TeV, gamma rays to 10 TeV and nuclei with Z=1 to 40 up to 1,000 TeV during a two-year mission on the International Space Station (ISS), extendable to five years. These measurements are essential to search for dark matter signatures, investigate the mechanism of cosmic-ray acceleration and propagation in the Galaxy and discover possible astrophysical sources of high-energy electrons nearby the Earth. The instrument consists of two layers of segmented plastic scintillators for the cosmic-ray charge identification (CHD), a 3 radiation length thick tungsten-scintillating fiber imaging calorimeter (IMC) and a 27 radiation length thick lead-tungstate calorimeter (TASC). CALET has sufficient depth, imaging capabilities and excellent energy resolution to allow for a clear separation between hadrons and electrons and between charged particles and gamma rays. The instrument will be launched to the ISS within 2014 Japanese Fiscal Year (by the end of March 2015) and installed on the Japanese Experiment Module-Exposed Facility (JEM-EF). In this paper, we will review the status and main science goals of the mission and describe the instrument configuration and performance.

  17. Study of the Status of Physicians-Patient Communication among Medical Interns

    Sa’eedeh Farajzadeh

    2009-02-01

    Full Text Available Background and purpose: Proper communication between a physician and a patient is the key to diagnosis and management of diseases.Communication skills are essential for gathering information from patients, enhancing patients trust on physicians, relaxing them and managing them .The main purpose of this study was to determine the states of communication skills of medical interns to communicate with patients.Method: In this cross sectional study, communication skills of 72 medical interns of Kerman Medical University was assessed based on a checklist completed with direct observation and a questionnaire completed through interview with patients.The checklist included two parts: the first part for individual characteristics and the second part for 24 specifications related to initiation of an interview, conducting an interview and completion of aninterview.Another questionnaire with a similar structure was developed to gather patients’ comments about communication of medical interns with them.Results: Communication skills of medical interns were weak in 29.3%, moderate in 85.4% and good in 15.9% of interns. An agreement between observed communication skills and patients’ survey results about greeting, asking patients’ names and calling them by their names, acceptable physicians’ appearance, listening to patients’ words, friendly doctor- patient encounter, empathizing with patients (0.37, 0.26, 0.22.0.41and 0.44 respectively was seen. Results of individual variables show that relationship between age of patient and his or her opinion about communication was significant.Based on patient’s survey, the communication score given to the student increases with age of the patient.Conclusion: The study shows deficits in doctor-patient communication of medical interns in history taking. Given the importance of communication skills, the necessity to teach them in clinical skill centers before real contact with patients is obvious

  18. A Summary of - An Earth-to-Deep Space Communications System with Adaptive Tilt and Scintillation Correction Using Near-Earth Relay Mirrors

    Armstrong, J. W.; Yeh, C.; Wilson, K. E.

    1998-01-01

    Optical telecommunication will be the next technology for wide-band Earth/space communication. Uncompensated propagation through the Earth's atmosphere (e.g., scintillation and wavefront tilt) fundamentally degrade communication to distant spcaecraft.

  19. Psycho-education's impact on communication skills, self-esteem and anger expression status of emergency medical technical student

    Sevinc Mersin

    2015-12-01

    Full Text Available Aim: Emergency medical students are first persons that encountered and make medical aids to patients or traumatized people. It is stated that having adequate facilities about the communication of each health workers to deal with emergency patient and wounded persons is as important as immediate treatment. This research was conducted as quasi-experimental in order to determine the education of emotion recognition and expression's impact on communication skills, self-esteem and anger expression status of emergency medical technical students. Methods: The research was made with 7 students in first year of education in emergency department at a university in Turkey in 2013-2014 academic years. Total 12-session education of emotion recognition and expression was given to student within research for 2 hours in a week during 12 weeks. Information Form including socio-demographic characteristics, Communication Skills Inventory (CSI, Rosenberg Self-Esteem Scale (RSES and Spielberger Trait Anger Scale (STAS were applied to students before and after psycho-education. Results: It was determined that CSI mean scores of students within research were high before and after psycho-education but there is no statistically difference between them. It was determined that also there is no significantly difference between students' RSES and STAS mean scores before and after psycho-education. Conclusion: It was determined in the research that education of emotion recognition and expression has no impact on communication skills, self-esteem and anger expression status of students and students' communication skills levels were high before and after psycho-education. It has been concluded that especially empathy from communication skills is the mode of existence and therefore cannot be taught. [TAF Prev Med Bull 2015; 14(6.000: 489-495

  20. Status of an advanced radioisotope space power system using free-piston Stirling technology

    White, M.A.; Qiu, S.; Erbeznik, R.M.; Olan, R.W.; Welty, S.C.

    1998-01-01

    This paper describes a free-piston Stirling engine technology project to demonstrate a high efficiency power system capable of being further developed for deep space missions using a radioisotope (RI) heat source. The key objective is to develop a power system with an efficiency exceeding 20% that can function with a high degree of reliability for 10 years or longer on deep space missions. Primary issues being addressed for Stirling space power systems are weight and the vibration associated with reciprocating pistons. Similar weight and vibration issues have been successfully addressed with Stirling cryocoolers, which are the accepted standard for cryogenic cooling in space. Integrated long-life Stirling engine-generator (or convertor) operation has been demonstrated by the terrestrial Radioisotope Stirling Generator (RSG) and other Stirling Technology Company (STC) programs. Extensive RSG endurance testing includes more than 40,000 maintenance-free, degradation-free hours for the complete convertor, in addition to several critical component and subsystem endurance tests. The Stirling space power convertor project is being conducted by STC under DOE Contract, and NASA SBIR Phase II contracts. The DOE contract objective is to demonstrate a two-convertor module that represents half of a nominal 150-W(e) power system. Each convertor is referred to as a Technology Demonstration Convertor (TDC). The ultimate Stirling power system would be fueled by three general purpose heat source (GPHS) modules, and is projected to produce substantially more electric power than the 150-watt target. The system is capable of full power output with one failed convertor. One NASA contract, nearing completion, uses existing 350-W(e) RG-350 convertors to evaluate interactivity of two back-to-back balanced convertors with various degrees of electrical and mechanical interaction. This effort has recently provided the first successful synchronization of two convertors by means of parallel

  1. What is the public's role in 'space' policymaking? Images of the public by practitioners of 'space' communication in the United Kingdom.

    Entradas, Marta

    2016-07-01

    Studies on experts' understanding of the public have mainly focused on the views of scientists. We add to the literature on constructions of the public by analyzing the views of decision-makers, professional science communicators and scientists involved in 'space' communication on the public and public participation in policy. Findings show that contextual situations and roles determine the way the public is conceptualised: the public is sophisticated and knowledgeable to participate in space activities/citizen science, but in matters of policy, a gullible image of the public is brought up. Despite the democratic talk on participation, practitioners delimited public involvement in policy in some way or other to protect their own power and decision-making capabilities. This conception of the public competes with the stated aims of scientific and political institutions for public engagement and the substantive value of public participation, leaving a limited role for the public in space policymaking. © The Author(s) 2015.

  2. Ground Radar Polarimetric Observations of High-Frequency Earth-Space Communication Links

    Bolen, Steve; Chandrasekar, V.; Benjamin, Andrew

    2002-01-01

    Strategic roadmaps for NASA's Human Exploration and Development of Space (REDS) enterprise support near-term high-frequency communication systems that provide moderate to high data rates with dependable service. Near-earth and human planetary exploration will baseline Ka-Band, but may ultimately require the use of even higher frequencies. Increased commercial demand on low-frequency earth-space bands has also led to increased interest in the use of higher frequencies in regions like K u - and K,- band. Data is taken from the Tropical Rainfall Measuring Mission (TRMM) Precipitation Radar (PR), which operates at 13.8 GHz, and the true radar reflectivity profile is determined along the PR beam via low-frequency ground based polarimetric observations. The specific differential phase (Kdp) is measured along the beam and a theoretical model is used to determine the expected specific attenuation (k). This technique, called the k-Kdp method, uses a Fuzzy-Logic model to determine the hydrometeor type along the PR beam from which the appropriate k-Kdp relationship is used to determine k and, ultimately, the total path-integrated attenuation (PIA) on PR measurements. Measurements from PR and the NCAR S-POL radar were made during the TEFLUN-B experiment that took place near Melbourne, FL in 1998, and the TRMM-LBA campaign near Ji-Parana, Brazil in 1999.

  3. Performance analysis of stationary Hadamard matrix diffusers in free-space optical communication links

    Burrell, Derek J.; Middlebrook, Christopher T.

    2017-08-01

    Wireless communication systems that employ free-space optical links in place of radio/microwave technologies carry substantial benefits in terms of data throughput, network security and design efficiency. Along with these advantages comes the challenge of counteracting signal degradation caused by atmospheric turbulence in free-space environments. A fully coherent laser source experiences random phase delays along its traversing path in turbulent conditions forming a speckle pattern and lowering the received signal-to-noise ratio upon detection. Preliminary research has shown that receiver-side speckle contrast may be significantly reduced and signal-to-noise ratio increased accordingly through the use of a partially coherent light source. While dynamic diffusers and adaptive optics solutions have been proven effective, they also add expense and complexity to a system that relies on accessibility and robustness for successful implementation. A custom Hadamard diffractive matrix design is used to statically induce partial coherence in a transmitted beam to increase signal-to-noise ratio for experimental turbulence scenarios. Atmospheric phase screens are generated using an open-source software package and subsequently loaded into a spatial light modulator using nematic liquid crystals to modulate the phase.

  4. The impact of emotional intelligence, self-esteem, and self-image on romantic communication over MySpace.

    Dong, Qingwen; Urista, Mark A; Gundrum, Duane

    2008-10-01

    A study based on a survey of 240 individual MySpace users found that low self-esteem encourages young adults to engage in romantic communication (such as having intimate communication with the opposite sex and looking for romantic partners) while higher emotional intelligence discourages such activity. The results also suggested that those who have higher self-image, such as thinking themselves attractive and happy with their appearance, tend to engage in romantic communication. Limitations of the study and suggestion for future study are discussed.

  5. Space to Space Communication Subsystem Manned Spaceflight and Its Key Technology%载人航天空空通信子系统及其关键技术

    石云墀

    2011-01-01

    The composition of the space to space communication subsystem which would realize the transmit the data between Shenzhou spaceship and Tiangong target spacecraft and the functiofi and main performances of the space to space communicator were introduced in this paper. The DS/SS technology which could provide very good performance in anti-jamming and secret communication was applied in the space to space communication subsystem. And the key technologies of sequence synchronization and carrier synchronization in the demodulation of IF DS/SS signal which was the core in DS/SS were analyzed. Using the digital demodulation scheme would reduce the complexity of debugging and increase the reliability of the system.%介绍了实现神舟运输飞船与天宫目标飞行器间数据通信和传输的空空通信子系统的构成,以及空空通信机的功能及其主要性能指标。空空通信子系统采用抗干扰能力强、保密性优的直接序列扩频通信技术。分析了其中的核心中频解扩解调中的伪码同步和载波同步等关键技术,应用数字解调方案降低了子系统调试难度,提高了可靠性。

  6. Analog Testing of Operations Concepts for Mitigation of Communication Latency During Human Space Exploration

    Chappell, Steven P.; Abercromby, Andrew F.; Miller, Matthew J.; Halcon, Christopher; Gernhardt, Michael L.

    2016-01-01

    OBJECTIVES: NASA Extreme Environment Mission Operations (NEEMO) is an underwater spaceflight analog that allows a true mission-like operational environment and uses buoyancy effects and added weight to simulate different gravity levels. Three missions were undertaken from 2014-2015, NEEMO's 18-20. All missions were performed at the Aquarius undersea research habitat. During each mission, the effects of varying operations concepts and tasks type and complexity on representative communication latencies associated with Mars missions were studied. METHODS: 12 subjects (4 per mission) were weighed out to simulate near-zero or partial gravity extravehicular activity (EVA) and evaluated different operations concepts for integration and management of a simulated Earth-based science backroom team (SBT) to provide input and direction during exploration activities. Exploration traverses were planned in advance based on precursor data collected. Subjects completed science-related tasks including presampling surveys, geologic-based sampling, and marine-based sampling as a portion of their tasks on saturation dives up to 4 hours in duration that were to simulate extravehicular activity (EVA) on Mars or the moons of Mars. One-way communication latencies, 5 and 10 minutes between space and mission control, were simulated throughout the missions. Objective data included task completion times, total EVA times, crew idle time, translation time, SBT assimilation time (defined as time available for SBT to discuss data/imagery after it has been collected, in addition to the time taken to watch imagery streaming over latency). Subjective data included acceptability, simulation quality, capability assessment ratings, and comments. RESULTS: Precursor data can be used effectively to plan and execute exploration traverse EVAs (plans included detailed location of science sites, high-fidelity imagery of the sites, and directions to landmarks of interest within a site). Operations concepts that

  7. NEEMO 18-20: Analog Testing for Mitigation of Communication Latency During Human Space Exploration

    Chappell, Steven P.; Beaton, Kara H.; Miller, Matthew J.; Graff, Trevor G.; Abercromby, Andrew F. J.; Gernhardt, Michael L.; Halcon, Christopher

    2016-01-01

    NASA Extreme Environment Mission Operations (NEEMO) is an underwater spaceflight analog that allows a true mission-like operational environment and uses buoyancy effects and added weight to simulate different gravity levels. Three missions were undertaken from 2014-2015, NEEMO's 18-20. All missions were performed at the Aquarius undersea research habitat. During each mission, the effects of communication latencies on operations concepts, timelines, and tasks were studied. METHODS: Twelve subjects (4 per mission) were weighed out to simulate near-zero or partial gravity extravehicular activity (EVA) and evaluated different operations concepts for integration and management of a simulated Earth-based science team (ST) to provide input and direction during exploration activities. Exploration traverses were preplanned based on precursor data. Subjects completed science-related tasks including pre-sampling surveys, geologic-based sampling, and marine-based sampling as a portion of their tasks on saturation dives up to 4 hours in duration that were designed to simulate extravehicular activity (EVA) on Mars or the moons of Mars. One-way communication latencies, 5 and 10 minutes between space and mission control, were simulated throughout the missions. Objective data included task completion times, total EVA times, crew idle time, translation time, ST assimilation time (defined as time available for ST to discuss data/imagery after data acquisition). Subjective data included acceptability, simulation quality, capability assessment ratings, and comments. RESULTS: Precursor data can be used effectively to plan and execute exploration traverse EVAs (plans included detailed location of science sites, high-fidelity imagery of the sites, and directions to landmarks of interest within a site). Operations concepts that allow for pre-sampling surveys enable efficient traverse execution and meaningful Mission Control Center (MCC) interaction across communication latencies and can be

  8. Does Marital Status of Parents Relate to Family Communication Regarding Finances?

    Teresa A. Mauldin

    2011-03-01

    Full Text Available How do youth and parents perceive their communication with each other? How do they perceive communication about money with each other? Are there differences between married-parent families and single-parent families? The reported study examined the discrepancies in perception between parents and youth and compares these differences between married and single-parent families. Although single-parent families had greater discrepancies in perceptions regarding communication in general, there was no evidence of such differences in discrepancies regarding communication about money. The finding suggests the importance of youth development programs to provide information and encouragement to both youth and their parents.

  9. Combining Social Media with Innovative Ways of Communicating about the James Webb Space Telescope

    Masetti, Margaret

    2012-01-01

    In keeping with the cutting-edge nature of the James Webb Space Telescope, NASA is using a variety of social and interactive media to engage the public. While we do have a regularly updated static website, we are now also using various interactives (like Flash games and a 3D Tour of the spacecraft) to better explain what the Webb telescope is and how it works. To encourage future generations, we are a partner in an educational engineering design challenge which makes use of a virtual Second Life-like world. Additionally, the public can now watch Webb come together before their eyes by accessing our live webcam, which shows telescope hardware being built in our cleanroom. We are working to make Webb as much of a part of pop culture as the Hubble Space Telescope is. We facilitated the filming of a "Late Night with Jimmy Fallon” segment (called "Hubble Gotchu") featuring Webb and Webb scientists at NASA's Goddard Space Flight Center. A visit to the highly rated sitcom "The Big Bang Theory” resulted in Webb lithos, magnets, posters, a scale model, and more being regularly featured on the set of the show. The most important aspect to creating interesting ways to engage the public is having the ability to communicate and form relationships with as many people as possible. To that end, we are using tools like blogs (e.g., NASA Blueshift) and popular social media (Facebook, Twitter, YouTube, and Flickr) to reach out to as many people as we can and to enable them to share and spread the content we provide.

  10. Mexican American mothers of low and middle socioeconomic status: communication behaviors and interactive strategies during shared book reading.

    Rodríguez, Barbara L; Hines, Rachel; Montiel, Miguel

    2009-07-01

    The aim of this investigation was to describe and compare the communication behaviors and interactive reading strategies used by Mexican American mothers of low- and middle-socioeconomic status (SES) background during shared book reading. Twenty Mexican American mother-child dyads from the Southwestern United States were observed during two book reading sessions. The data were coded across a number of communication behavior categories and were analyzed using the Adult/Child Interactive Reading Inventory (ACIRI; A. DeBruin-Parecki, 1999). Mexican American mothers used a variety of communication behaviors during shared book reading with their preschool children. Significant differences between the SES groups regarding the frequency of specific communication behaviors were revealed. Middle-SES mothers used positive feedback and yes/no questions more often than did low-SES mothers. Mexican American mothers also used a variety of interactive reading strategies with varying frequency, as measured by the ACIRI. They enhanced attention to text some of the time, but rarely promoted interactive reading/supported comprehension or used literacy strategies. There were no significant differences between the SES groups regarding the frequency of interactive reading strategies. Parent literacy programs should supplement Mexican American mothers' communication behaviors and interactive reading strategies to improve effectiveness and participation.

  11. A Common Communications, Navigation and Surveillance Infrastructure for Accommodating Space Vehicles in the Next Generation Air Transportation System

    VanSuetendael, RIchard; Hayes, Alan; Birr, Richard

    2008-01-01

    Suborbital space flight and space tourism are new potential markets that could significantly impact the National Airspace System (NAS). Numerous private companies are developing space flight capabilities to capture a piece of an emerging commercial space transportation market. These entrepreneurs share a common vision that sees commercial space flight as a profitable venture. Additionally, U.S. space exploration policy and national defense will impose significant additional demands on the NAS. Air traffic service providers must allow all users fair access to limited airspace, while ensuring that the highest levels of safety, security, and efficiency are maintained. The FAA's Next Generation Air Transportation System (NextGen) will need to accommodate spacecraft transitioning to and from space through the NAS. To accomplish this, space and air traffic operations will need to be seamlessly integrated under some common communications, navigation and surveillance (CNS) infrastructure. As part of NextGen, the FAA has been developing the Automatic Dependent Surveillance Broadcast (ADS-B) which utilizes the Global Positioning System (GPS) to track and separate aircraft. Another key component of NextGen, System-Wide Information Management/ Network Enabled Operations (SWIM/NEO), is an open architecture network that will provide NAS data to various customers, system tools and applications. NASA and DoD are currently developing a space-based range (SBR) concept that also utilizes GPS, communications satellites and other CNS assets. The future SBR will have very similar utility for space operations as ADS-B and SWIM has for air traffic. Perhaps the FAA, NASA, and DoD should consider developing a common space-based CNS infrastructure to support both aviation and space transportation operations. This paper suggests specific areas of research for developing a CNS infrastructure that can accommodate spacecraft and other new types of vehicles as an integrated part of NextGen.

  12. New mission requirements methodologies for services provided by the Office of Space Communications

    Holmes, Dwight P.; Hall, J. R.; Macoughtry, William; Spearing, Robert

    1993-01-01

    The Office of Space Communications, NASA Headquarters, has recently revised its methodology for receiving, accepting and responding to customer requests for use of that office's tracking and communications capabilities. This revision is the result of a process which has become over-burdened by the size of the currently active and proposed missions set, requirements reviews that focus on single missions rather than on mission sets, and negotiations most often not completed early enough to effect needed additions to capacity or capability prior to launch. The requirements-coverage methodology described is more responsive to project/program needs and provides integrated input into the NASA budget process early enough to effect change, and describes the mechanisms and tools in place to insure a value-added process which will benefit both NASA and its customers. Key features of the requirements methodology include the establishment of a mechanism for early identification of and systems trades with new customers, and delegates the review and approval of requirements documents to NASA centers in lieu of Headquarters, thus empowering the system design teams to establish and negotiate the detailed requirements with the user. A Mission Requirements Request (MRR) is introduced to facilitate early customer interaction. The expected result is that the time to achieve an approved set of implementation requirements which meet the customer's needs can be greatly reduced. Finally, by increasing the discipline in requirements management, through the use of base lining procedures, a tighter coupling between customer requirements and the budget is provided. A twice-yearly projection of customer requirements accommodation, designated as the Capacity Projection Plan (CPP), provides customer feedback allowing the entire mission set to be serviced.

  13. Do features of public open spaces vary according to neighbourhood socio-economic status?

    Crawford, David; Timperio, Anna; Giles-Corti, Billie; Ball, Kylie; Hume, Clare; Roberts, Rebecca; Andrianopoulos, Nick; Salmon, Jo

    2008-12-01

    This study examined the relations between neighbourhood socio-economic status and features of public open spaces (POS) hypothesised to influence children's physical activity. Data were from the first follow-up of the Children Living in Active Neighbourhoods (CLAN) Study, which involved 540 families of 5-6 and 10-12-year-old children in Melbourne, Australia. The Socio-Economic Index for Areas Index (SEIFA) of Relative Socio-economic Advantage/Disadvantage was used to assign a socioeconomic index score to each child's neighbourhood, based on postcode. Participant addresses were geocoded using a Geographic Information System. The Open Space 2002 spatial data set was used to identify all POS within an 800 m radius of each participant's home. The features of each of these POS (1497) were audited. Variability of POS features was examined across quintiles of neighbourhood SEIFA. Compared with POS in lower socioeconomic neighbourhoods, POS in the highest socioeconomic neighbourhoods had more amenities (e.g. picnic tables and drink fountains) and were more likely to have trees that provided shade, a water feature (e.g. pond, creek), walking and cycling paths, lighting, signage regarding dog access and signage restricting other activities. There were no differences across neighbourhoods in the number of playgrounds or the number of recreation facilities (e.g. number of sports catered for on courts and ovals, the presence of other facilities such as athletics tracks, skateboarding facility and swimming pool). This study suggests that POS in high socioeconomic neighbourhoods possess more features that are likely to promote physical activity amongst children.

  14. Knowledge, Communication and E-learning in Higher Education Perception and Differences of Traditional and Modern Academic Status

    Silvia-Adriana Tomescu

    2010-06-01

    Full Text Available The aim of the present analyze is to underline the importance of a systemic approach of knowledge communication in eLearning academic sphere, in order to improve the efficiency and quality of research. Atthe same time, we intend to notice and shape the evolution of both teacher and learner status in higher education. The rhetoric about knowledge is often associated with organization and transfer of information. To provide students with a modern understanding of the „shared values” in higher education has become an important objective. The teachers have to adapt new forms of e-delivery of discipline content, form and inform about e-resources for learning. We have to develop national strategies and add value to the role ofuniversity as a key factor in e-learning. The knowledge transfer at academic level, can be fully realized only when information encounters in the student the optimal set of tools designed to facilitate learning, and an individual style of thinking, so as to analyze fundamental questions and to be able to validate or invalidate the information. The teacher status evolves from content expert to metacognition expert, from guide in valuable information search to knowledge communicator. The present analyze reflects some aspects of the consequences that new forms of communication evolved during transition from traditional to e-academic environment.

  15. Aspects of scintillation modelling in LEO-ground free-space optical communications

    Moll, Florian

    2017-10-01

    Free-space optical communications can be used to transmit data from low Earth orbit satellites to ground with very high data rate. In the last section of the downlink, the electro-magnetic wave propagates through the turbulent atmosphere which is characterized by random index of refraction fluctuations. The propagating wave experiences phase distortions that lead to intensity scintillation in the aperture plane of the receiving telescope. For quantification, an appropriate scintillation model is needed. Approaches to analytically model the scintillation exist. Parameterization of the underlying turbulence profile (Cn2 profile) is however difficult. The Cn2 profiles are often site-specific and thus inappropriate or generic and thus too complex for a feasible deployment. An approach that directly models the scintillation effect based on measurements without claiming to be generic is therefore more feasible. Since measurements are sparse, a combination with existing theoretical framework is feasible to develop a new scintillation model that focuses on low earth orbit to ground free-space optical communications link design with direct detection. The paper addresses several questions one has to answer while analyzing the measurements data and selection of the theoretical models for the LEO downlink scenario. The first is the question of a suitable yet ease to use simple Cn2 profile. The HAP model is analyzed for its feasibility in this scenario since it includes a more realistic boundary layer profile decay than the HV model. It is found that the HAP model needs to be modified for a feasible deployment in the LEO downlink scenario for night time. The validity of the plane wave assumption in the downlink is discussed by model calculations of the scintillation index for a plane and Gaussian beam wave. Inaccuracies when using the plane earth model instead of the spherical earth model are investigated by analyzing the Rytov index. Impact of beam wander and non

  16. COTS low-cost 622-Mb/s free-space laser communications link for short-distance commercial applications

    Morrison, Kenneth A.

    2000-05-01

    The results from a low cost 622 Mb/s, free-space laser communication link operating at 850 nm for short distance commercial applications is presented. The test results demonstrate the use of a free-space laser communications transceiver for building to building applications such as LAN, WAN and ATM operations, etc. This illustrates the potential for wide-use commercial computer network applications. The transceiver is constructed of commercial off-the-shelf materials for the development of a low-cost laser communications data link. The test system configuration utilizes standard Personal Computers with network cards and signal conversion cards for the copper to optical medical conversion. These tests precede the development of an increased data rate device operating at 2.5 Gb/s.

  17. Tactile Communications

    National Aeronautics and Space Administration — Communication with the crew is vital and must be maintained regardless of environmental conditions and crew activity. Current spacecraft communication systems depend...

  18. Conceptualizing and communicating organizational risk dynamics in the thoroughness-efficiency space

    Marais, K.B.; Saleh, J.H.

    2008-01-01

    Organizations that design and/or operate complex systems have to make trade-offs between multiple, interacting, and sometimes conflicting goals at both the individual and organizational levels. Identifying, communicating, and resolving the conflict or tension between multiple organizational goals is challenging. Furthermore, maintaining an appropriate level of safety in such complex environments is difficult for a number of reasons discussed in this paper. The objective of this paper is to propose a set of related concepts that can help conceptualize organizational risk and help managers to understand the implications of various performance and resource pressures and make appropriate trade-offs between efficiency and thoroughness that maintain system safety. The concepts here introduced include (1) the thoroughness-efficiency space for classifying organizational behavior, and the various resource/performance and regulatory pressures that can displace organizations from one quadrant to another within this space, (2) the thoroughness-efficiency barrier and safety threshold, and (3) the efficiency penalty that organizations should accept, and not trade against organizational thoroughness, in order to maintain safety. Unfortunately, many accidents share a conceptual sameness in the way they occur. That sameness can be related to the dynamics conceptualized in this paper and the violation of the safety threshold. This sameness is the sad story of the Bhopal accident, the Piper Alpha accident, and score of others. Finally, we highlight the importance of a positive safety culture as an essential complement to regulatory pressure in maintaining safety. We illustrate the 'slippery slope of thoroughness' along which organizational behavior slides under the influence of performance pressure, and suggest that a positive safety culture can be conceived of as 'pulling this slippery slope' up and preventing the violation of the safety threshold

  19. Status and Mission Applicability of NASA's In-Space Propulsion Technology Project

    Anderson, David J.; Munk, Michelle M.; Dankanich, John; Pencil, Eric; Liou, Larry

    2009-01-01

    The In-Space Propulsion Technology (ISPT) project develops propulsion technologies that will enable or enhance NASA robotic science missions. Since 2001, the ISPT project developed and delivered products to assist technology infusion and quantify mission applicability and benefits through mission analysis and tools. These in-space propulsion technologies are applicable, and potentially enabling for flagship destinations currently under evaluation, as well as having broad applicability to future Discovery and New Frontiers mission solicitations. This paper provides status of the technology development, near-term mission benefits, applicability, and availability of in-space propulsion technologies in the areas of advanced chemical thrusters, electric propulsion, aerocapture, and systems analysis tools. The current chemical propulsion investment is on the high-temperature Advanced Material Bipropellant Rocket (AMBR) engine providing higher performance for lower cost. Investments in electric propulsion technologies focused on completing NASA's Evolutionary Xenon Thruster (NEXT) ion propulsion system, a 0.6-7 kW throttle-able gridded ion system, and the High Voltage Hall Accelerator (HiVHAC) thruster, which is a mid-term product specifically designed for a low-cost electric propulsion option. Aerocapture investments developed a family of thermal protections system materials and structures; guidance, navigation, and control models of blunt-body rigid aeroshells; atmospheric models for Earth, Titan, Mars and Venus; and models for aerothermal effects. In 2009 ISPT started the development of propulsion technologies that would enable future sample return missions. The paper describes the ISPT project's future focus on propulsion for sample return missions. The future technology development areas for ISPT is: Planetary Ascent Vehicles (PAV), with a Mars Ascent Vehicle (MAV) being the initial development focus; multi-mission technologies for Earth Entry Vehicles (MMEEV) needed

  20. Examination of Communication Delays on Team Performance: Utilizing the International Space Station (ISS) as a Test Bed for Analog Research

    Keeton, K. E.; Slack, K, J.; Schmidt, L. L.; Ploutz-Snyder, R.; Baskin, P.; Leveton, L. B.

    2011-01-01

    Operational conjectures about space exploration missions of the future indicate that space crews will need to be more autonomous from mission control and operate independently. This is in part due to the expectation that communication quality between the ground and exploration crews will be more limited and delayed. Because of potential adverse effects on communication quality, both researchers and operational training and engineering experts have suggested that communication delays and the impact these delays have on the quality of communications to the crew will create performance decrements if crews are not given adequate training and tools to support more autonomous operations. This presentation will provide an overview of a research study led by the Behavioral Health and Performance Element (BHP) of the NASA Human Research Program that examines the impact of implementing a communication delay on ISS on individual and team factors and outcomes, including performance and related perceptions of autonomy. The methodological design, data collection efforts, and initial results of this study to date will be discussed . The results will focus on completed missions, DRATS and NEEMO15. Lessons learned from implementing this study within analog environments will also be discussed. One lesson learned is that the complexities of garnishing a successful data collection campaign from these high fidelity analogs requires perseverance and a strong relationship with operational experts. Results of this study will provide a preliminary understanding of the impact of communication delays on individual and team performance as well as an insight into how teams perform and interact in a space-like environment . This will help prepare for implementation of communication delay tests on the ISS, targeted for Increment 35/36.

  1. Audiovisual quality assessment in communications applications: Current status, trends and challenges

    Korhonen, Jari

    2010-01-01

    Audiovisual quality assessment is one of the major challenges in multimedia communications. Traditionally, algorithm-based (objective) assessment methods have focused primarily on the compression artifacts. However, compression is only one of the numerous factors influencing the perception...... addressed in practical quality metrics is the co-impact of audio and video qualities. This paper provides an overview of the current trends and challenges in objective audiovisual quality assessment, with emphasis on communication applications...

  2. Free-space laser communication technologies IV; Proceedings of the 4th Conference, Los Angeles, CA, Jan. 23, 24, 1992

    Begley, David L. (Editor); Seery, Bernard D. (Editor)

    1992-01-01

    Papers included in this volume are grouped under topics of receivers; laser transmitters; components; system analysis, performance, and applications; and beam control (pointing, acquisition, and tracking). Papers are presented on an experimental determination of power penalty contributions in an optical Costas-type phase-locked loop receiver, a resonant laser receiver for free-space laser communications, a simple low-loss technique for frequency-locking lasers, direct phase modulation of laser diodes, and a silex beacon. Particular attention is given to experimental results on an optical array antenna for nonmechanical beam steering, a potassium Faraday anomalous dispersion optical filter, a 100-Mbps resonant cavity phase modulator for coherent optical communications, a numerical simulation of a 325-Mbit/s QPPM optical communication system, design options for an optical multiple-access data relay terminal, CCD-based optical tracking loop design trades, and an analysis of a spatial-tracking subsystem for optical communications.

  3. Docosahexaenoic acid status at 9 months is inversely associated with communicative skills in 3-year-old girls

    Engel, Sara; Tronhjem, Kathrine Marie Hagerup; Hellgren, Lars

    2013-01-01

    by the parents using third edition of the Ages and Stages Questionnaire (ASQ-3). RBC DHA levels ranged from 2.2% to 12.6% of the RBC fatty acids. The age of reaching milestones correlated with psychomotor development, particularly with gross motor function at 3 years. An association between milestones and later...... personal and social skills was also observed, but only for girls. In girls, RBC-DHA was found to be inversely correlated with communication at 3 years of age (odds ratio = 0.69, 95% confidence interval: 0.56-0.86, P = 0.001), but no other associations with psychomotor development or milestones were found....... The results from study indicate that DHA status at 9 months may not have a pronounced beneficial effect on psychomotor development in early childhood and that communicative skills at 3 years of age may even be inversely associated with early RBC-DHA levels in girls....

  4. Performance analysis of an adaptive optics system for free-space optics communication through atmospheric turbulence.

    Wang, Yukun; Xu, Huanyu; Li, Dayu; Wang, Rui; Jin, Chengbin; Yin, Xianghui; Gao, Shijie; Mu, Quanquan; Xuan, Li; Cao, Zhaoliang

    2018-01-18

    The performance of free-space optics communication (FSOC) is greatly degraded by atmospheric turbulence. Adaptive optics (AO) is an effective method for attenuating the influence. In this paper, the influence of the spatial and temporal characteristics of turbulence on the performance of AO in a FSOC system is investigated. Based on the Greenwood frequency (GF) and the ratio of receiver aperture diameter to atmospheric coherent length (D/r 0 ), the relationship between FSOC performance (CE) and AO parameters (corrected Zernike modes number and bandwidth) is derived for the first time. Then, simulations and experiments are conducted to analyze the influence of AO parameters on FSOC performance under different GF and D/r 0 . The simulation and experimental results show that, for common turbulence conditions, the number of corrected Zernike modes can be fixed at 35 and the bandwidth of the AO system should be larger than the GF. Measurements of the bit error rate (BER) for moderate turbulence conditions (D/r 0  = 10, f G  = 60 Hz) show that when the bandwidth is two times that of GF, the average BER is decreased by two orders of magnitude compared with f G /f 3dB  = 1. These results and conclusions can provide important guidance in the design of an AO system for FSOC.

  5. A Very Large Area Network (VLAN) knowledge-base applied to space communication problems

    Zander, Carol S.

    1988-01-01

    This paper first describes a hierarchical model for very large area networks (VLAN). Space communication problems whose solution could profit by the model are discussed and then an enhanced version of this model incorporating the knowledge needed for the missile detection-destruction problem is presented. A satellite network or VLAN is a network which includes at least one satellite. Due to the complexity, a compromise between fully centralized and fully distributed network management has been adopted. Network nodes are assigned to a physically localized group, called a partition. Partitions consist of groups of cell nodes with one cell node acting as the organizer or master, called the Group Master (GM). Coordinating the group masters is a Partition Master (PM). Knowledge is also distributed hierarchically existing in at least two nodes. Each satellite node has a back-up earth node. Knowledge must be distributed in such a way so as to minimize information loss when a node fails. Thus the model is hierarchical both physically and informationally.

  6. Problems of linguistic discrimination in the communicative space of Tajikistan: legal, sociolinguistic and educational aspects

    Diloro Iskandarova

    2017-11-01

    Full Text Available Although it is disregarded and banned, a person can be discriminated in the society according to various attributes – due to the person's language, religion, nationality, social background. The problem touches upon not only individuals but minorities as well. Almost all states have one or several groups – minorities – that differ from the main population in ethnic, linguistic or religious lines. Most international treaties on human rights contain anti-discriminatory provisions. In addition to the main rights of the freedom of conscience, thought and associations, the principal legal guarantees for each representative of minorities consist in being treated equally by the law and courts and in equal protection of laws. The paper studies the problems of legal, sociolinguistic and educational basis of linguistic discrimination in the communicative space of Tajikistan. Linguistic discrimination and political correctness are closely connected with the language policy of the state. With exoglossic linguistic situation being characteristic for Tajikistan arises a need to study the questions related to linguistic discrimination. This will allow making certain adjustments to language building and harmonizing the ethnic and interethnic interests on the basis of a balanced and scientifically justified language policy.

  7. Performances of Free-Space Optical Communication System Over Strong Turbulence

    Ucuk Darusalam

    2014-08-01

    Full Text Available We report an experimental of free-space optical communication (FSOC system that use tube propagation simulator (TPS as the turbulence medium. The FSOC system usewavelength of 1550 nm at the rate transmission of 1000 Mbps and amplified with EDFA at the output of +23 dBm. Index structure of 10-15–10-13 as the representation of atmosphere index turbulences are used for simulation of intensity distribution model or scintillation. The simulation use gammagamma and K model as well. The beam wave propagation models used in simulation are plane wave, spherical wave and Gaussian wave. Spherical wave achieves highest performance via gamma-gamma in strong turbulence. While Gaussian wave achieves highest performance also via K model. We also found, characteristical FSOC system performance is calculated more accurately with gamma-gamma method for strong turbulence than K model. The performances from gamma-gamma for strong turbulenceare at 22.55 dB, at 5.33×10-4, and at 9.41 ×10-6. 

  8. Rethinking communication in innovation processes: creating space for change in complex systems

    Leeuwis, C.; Aarts, N.

    2011-01-01

    This paper systematically rethinks the role of communication in innovation processes, starting from largely separate theoretical developments in communication science and innovation studies. Literature review forms the basis of the arguments presented. The paper concludes that innovation is a

  9. Rethinking Communication in Innovation Processes: Creating Space for Change in Complex Systems

    Leeuwis, C.; Aarts, N.

    2011-01-01

    This paper systematically rethinks the role of communication in innovation processes, starting from largely separate theoretical developments in communication science and innovation studies. Literature review forms the basis of the arguments presented. The paper concludes that innovation is a

  10. Food intake and nutritional status during EXEMSI. Experimental Campaign for the European Manned Space Infrastructure.

    Milon, H; Decarli, B; Adine, A M; Kihm, E

    1996-01-01

    Modifications of food intake by astronauts during long-duration spaceflights have been observed. Various psychological stress factors, such as isolation, confinement, constrained community and boredom, are thought to play a role in this phenomenon. For this reason it was decided to include a nutritional investigation in the EXEMSI simulation study, in which four crew members (1 female and 3 males) were isolated and confined for 60 days in a space station-like environment. The Food and Nutritional Management System, developed for this experiment, provided on-line analysis of all available foods in terms of their nutrient content (macronutrients, water, minerals, vitamins). It permitted to keep an accurate record of the daily food intake of each crew member. The system has been shown to be a powerful tool for future missions, either simulations or actual spaceflights. It permits optimal management of food and eating on board, and offers the possibility of online analysis of the nutritional status of the crew. It can provide readily usable data for future analysis of nutritional variables in relation to other physiological and metabolic parameters. It could also supply a periodic feedback to the subject for the purpose of adjusting food intake. Eating and nutrition during the experiment were not a problem, but a pleasure, and therefore played an important role in its success. Confinement and isolation apparently had no effect on either the eating habits or the nutritional status of the crew members. The good food rather helped to decrease the potentially induced stress by providing daily periods of pleasure and of social activities. Detailed analysis of food intake showed erratic eating patterns, both before and during the experiment. However, the weekly averages of macro- and micronutrient intakes were in the normal range, except for vitamins B1 and B6 that were rather low and showed the need for supplements. Food appreciation was assessed by daily questionnaires

  11. High-Performance, Space-Storable, Bi-Propellant Program Status

    Schneider, Steven J.

    2002-01-01

    Bipropellant propulsion systems currently represent the largest bus subsystem for many missions. These missions range from low Earth orbit satellite to geosynchronous communications and planetary exploration. The payoff of high performance bipropellant systems is illustrated by the fact that Aerojet Redmond has qualified a commercial NTO/MMH engine based on the high Isp technology recently delivered by this program. They are now qualifying a NTO/hydrazine version of this engine. The advanced rhenium thrust chambers recently provided by this program have raised the performance of earth storable propellants from 315 sec to 328 sec of specific impulse. The recently introduced rhenium technology is the first new technology introduced to satellite propulsion in 30 years. Typically, the lead time required to develop and qualify new chemical thruster technology is not compatible with program development schedules. These technology development programs must be supported by a long term, Base R&T Program, if the technology s to be matured. This technology program then addresses the need for high performance, storable, on-board chemical propulsion for planetary rendezvous and descent/ascent. The primary NASA customer for this technology is Space Science, which identifies this need for such programs as Mars Surface Return, Titan Explorer, Neptune Orbiter, and Europa Lander. High performance (390 sec) chemical propulsion is estimated to add 105% payload to the Mars Sample Return mission or alternatively reduce the launch mass by 33%. In many cases, the use of existing (flight heritage) propellant technology is accommodated by reducing mission objectives and/or increasing enroute travel times sacrificing the science value per unit cost of the program. Therefore, a high performance storable thruster utilizing fluorinated oxidizers with hydrazine is being developed.

  12. Modelling of salad plants growth and physiological status in vitamin space greenhouse during lighting regime optimization

    Konovalova, Irina; Berkovich, Yuliy A.; Smolyanina, Svetlana; Erokhin, Alexei; Yakovleva, Olga; Lapach, Sergij; Radchenko, Stanislav; Znamenskii, Artem; Tarakanov, Ivan

    2016-07-01

    The efficiency of the photoautotrophic element as part of bio-engineering life-support systems is determined substantially by lighting regime. The artificial light regime optimization complexity results from the wide range of plant physiological functions controlled by light: trophic, informative, biosynthetical, etc. An average photosynthetic photon flux density (PPFD), light spectral composition and pulsed light effects on the crop growth and plant physiological status were studied in the multivariate experiment, including 16 independent experiments in 3 replicates. Chinese cabbage plants (Brassica chinensis L.), cultivar Vesnianka, were grown during 24 days in a climatic chamber under white and red light-emitting diodes (LEDs): photoperiod 24 h, PPFD from 260 to 500 µM/(m ^{2}*s), red light share in the spectrum varying from 33% to 73%, pulsed (pulse period from 30 to 501 µs) and non-pulsed lighting. The regressions of plant photosynthetic and biochemical indexes as well as the crop specific productivity in response to the selected parameters of lighting regime were calculated. Developed models of crop net photosynthesis and dark respiration revealed the most intense gas exchange area corresponding to PPFD level 450 - 500 µM/(m ^{2}*s) with red light share in the spectrum about 60% and the pulse length 30 µs with a pulse period from 300 to 400 µs. Shoot dry weight increased monotonically in response to the increasing PPFD and changed depending on the pulse period under stabilized PPFD level. An increase in ascorbic acid content in the shoot biomass was revealed when increasing red light share in spectrum from 33% to 73%. The lighting regime optimization criterion (Q) was designed for the vitamin space greenhouse as the maximum of a crop yield square on its ascorbic acid concentration, divided by the light energy consumption. The regression model of optimization criterion was constructed based on the experimental data. The analysis of the model made it

  13. The role of space communication in promoting national development with specific reference to experiments conducted in India

    Chitnis, E. V.

    The paper describes the role of space communication in promoting national development with special reference to experiments conducted in India, namely SITE (1975-1976), STEP (1977-1979) and APPLE (1981 onwards). The impact of these experiments in economic, cultural and educational terms are discussed, pointing out social implications involved in using advance space communication technology for instruction and information in the areas of education, national integration and development. The paper covers special requirements which arise when a communication system covers backward and remote rural areas in a developing country. The impact on the population measured by conducting social surveys has been discussed - especially the gains of predominently illiterate new media - participants have been highlighted. Possibilities of improving skills of teachers, the quality of the primary and higher education have been covered. The preparation required both on ground as well as space to derive benefits of space technology are considered. A profile of INSAT which marks the culmination of the experimental phase and the beginning of operational domestic satellite system is sketched.

  14. Prediction of rain effects on earth-space communication links operating in the 10 to 35 GHz frequency range

    Stutzman, Warren L.

    1989-01-01

    This paper reviews the effects of precipitation on earth-space communication links operating the 10 to 35 GHz frequency range. Emphasis is on the quantitative prediction of rain attenuation and depolarization. Discussions center on the models developed at Virginia Tech. Comments on other models are included as well as literature references to key works. Also included is the system level modeling for dual polarized communication systems with techniques for calculating antenna and propagation medium effects. Simple models for the calculation of average annual attenuation and cross-polarization discrimination (XPD) are presented. Calculation of worst month statistics are also presented.

  15. Development of Operational Free-Space-Optical (FSO) Laser Communication Systems Final Report CRADA No. TC02093.0

    Ruggiero, A. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Orgren, A. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

    2017-08-15

    This project was a collaborative effort between Lawrence Livermore National Security, LLC (formerly The Regents of the University of California)/Lawrence Livermore National Laboratory (LLNL) and LGS Innovations, LLC (formerly Lucent Technologies, Inc.), to develop long-range and mobile operational free-space optical (FSO) laser communication systems for specialized government applications. LLNL and LGS Innovations formerly Lucent Bell Laboratories Government Communications Systems performed this work for a United States Government (USG) Intelligence Work for Others (I-WFO) customer, also referred to as "Government Customer", or "Customer" and "Government Sponsor." The CRADA was a critical and required part of the LLNL technology transfer plan for the customer.

  16. Socioeconomic status, non-communicable disease risk factors, and walking speed in older adults: multi-cohort population based study.

    Stringhini, Silvia; Carmeli, Cristian; Jokela, Markus; Avendaño, Mauricio; McCrory, Cathal; d'Errico, Angelo; Bochud, Murielle; Barros, Henrique; Costa, Giuseppe; Chadeau-Hyam, Marc; Delpierre, Cyrille; Gandini, Martina; Fraga, Silvia; Goldberg, Marcel; Giles, Graham G; Lassale, Camille; Kenny, Rose Anne; Kelly-Irving, Michelle; Paccaud, Fred; Layte, Richard; Muennig, Peter; Marmot, Michael G; Ribeiro, Ana Isabel; Severi, Gianluca; Steptoe, Andrew; Shipley, Martin J; Zins, Marie; Mackenbach, Johan P; Vineis, Paolo; Kivimäki, Mika

    2018-03-23

    To assess the association of low socioeconomic status and risk factors for non-communicable diseases (diabetes, high alcohol intake, high blood pressure, obesity, physical inactivity, smoking) with loss of physical functioning at older ages. Multi-cohort population based study. 37 cohort studies from 24 countries in Europe, the United States, Latin America, Africa, and Asia, 1990-2017. 109 107 men and women aged 45-90 years. Physical functioning assessed using the walking speed test, a valid index of overall functional capacity. Years of functioning lost was computed as a metric to quantify the difference in walking speed between those exposed and unexposed to low socioeconomic status and risk factors. According to mixed model estimations, men aged 60 and of low socioeconomic status had the same walking speed as men aged 66.6 of high socioeconomic status (years of functioning lost 6.6 years, 95% confidence interval 5.0 to 9.4). The years of functioning lost for women were 4.6 (3.6 to 6.2). In men and women, respectively, 5.7 (4.4 to 8.1) and 5.4 (4.3 to 7.3) years of functioning were lost by age 60 due to insufficient physical activity, 5.1 (3.9 to 7.0) and 7.5 (6.1 to 9.5) due to obesity, 2.3 (1.6 to 3.4) and 3.0 (2.3 to 4.0) due to hypertension, 5.6 (4.2 to 8.0) and 6.3 (4.9 to 8.4) due to diabetes, and 3.0 (2.2 to 4.3) and 0.7 (0.1 to 1.5) due to tobacco use. In analyses restricted to high income countries, the number of years of functioning lost attributable to low socioeconomic status by age 60 was 8.0 (5.7 to 13.1) for men and 5.4 (4.0 to 8.0) for women, whereas in low and middle income countries it was 2.6 (0.2 to 6.8) for men and 2.7 (1.0 to 5.5) for women. Within high income countries, the number of years of functioning lost attributable to low socioeconomic status by age 60 was greater in the United States than in Europe. Physical functioning continued to decline as a function of unfavourable risk factors between ages 60 and 85. Years of functioning

  17. Hardware task-status manager for an RTOS with FIFO communication

    Zaykov, P.G.; Kuzmanov, G.; Molnos, A.M.; Goossens, K.G.W.

    2014-01-01

    In this paper, we address the problem of improving the performance of real-time embedded Multiprocessor System-on-Chip (MPSoC). Such MPSoCs often execute data-flow applications composed of multiple tasks, which communicate through First-In-First-Out (FIFO) queues. The tasks on each processor in the

  18. Socioeconomic Status and Its Effect on Teacher/Parental Communication in Schools

    Ankrum, Raymond J.

    2016-01-01

    The power of communication and community engagement utilized by teachers to actively involve parents and guardians in the educational process of their children is essential to the growth of the students. An important component to student motivation is a teacher's ability to leverage parental/guardian relationships. A teacher's ability to form…

  19. Status of the dedicated short-range communications technology and applications : report to Congress.

    2015-07-01

    This report responds to a Congressional request for an assessment of the 5.9 Gigahertz (GHz) Dedicated Short Range : Communications (DSRC) in accordance with the requirements provided by Congress in the Moving Ahead for Progress in the : 21st Century...

  20. EU-US standards harmonization task group report : status of ITS communication standards.

    2012-11-01

    Harmonization Task Groups 1 and 3 (HTG1 and 3) were established by the EU-US International Standards Harmonization Working Group to attempt to harmonize standards (including ISO, CEN, ETSI, IEEE) on security (HTG1) and communications protocols (HTG3)...

  1. "It's in Love with You". Communicating Status and Preference with Simple Product Movements

    Mortensen, Ditte Hvas; Hepworth, Sam J.; Berg, Kirstine Sonne

    2012-01-01

    In some situations users perceive product movements as an indication of agency. This makes it relevant to gain an understanding of how and why movements communicate attributes related to agency and what impact it has on users. This paper describes an experiment in which users, alone or in pairs, ...

  2. Space weather effects on airline communications in the high latitude regions

    Stocker, Alan; Siddle, Dave; Warrington, Mike; Honary, Farideh; Zaalov, Nikolay; Homam, Mariyam; Boteler, David; Danskin, Donald; de Franceschi, Georgiana; Ascaneus, Svend

    2013-04-01

    In the polar regions, ground-based VHF facilities for air-traffic control are lacking (and non-existent on the Russian side of the pole) and satellite communication systems either not available or expensive to retrofit to current aircraft and hence there remains a need for HF communication systems. Unfortunately, at these latitudes space weather can significantly affect the propagation of HF radio signals and the forecasting techniques currently employed by the airline industry are somewhat crude. In this paper, a new project that aims to provide forecasting of HF propagation characteristics for use by civilian airlines operating over polar routes will be described and preliminary results presented. Previous work in this area [e.g. Stocker et al., 2007] has focussed on taking HF signal measurements (e.g. SNR, delay and Doppler spread, and direction of arrival) on a limited number of propagation paths and developing an ionospheric model that incorporates high latitude features (e.g. polar patches and arcs) which, when combined with raytracing, allows the broad characteristics of the observations to be reproduced [Warrington et al., 2012]. The new project will greatly extend this work and consists of a number of stages. Firstly, HF measurements from an extensive network of purpose built transmitters and receivers spanning the Arctic regions will be collected and analysed. In order to test a wide variety of scenarios, the propagation paths will have different characteristics, e.g. different lengths and covering different parts of the northern ionosphere (i.e. polar cap paths where both terminals are in the polar cap, trans-auroral paths, and sub-auroral paths) and observations will be taken at a range of HF frequencies for a period covering the current (so far weak) solar maximum and part of the declining phase. Simultaneously, high latitude absorption measurements utilising the Global Riometer Array (GLORIA) will be collected and analysed. Next, the observations of

  3. Conclusions of ESA 1st Optical Wireless Onboard Communications Workshop: Current Status and the Road Forward

    Hernandez, Inmaculada; Plancke, Patrick

    2005-01-01

    The purpose of this workshop was to bring together representatives of European space agencies, aerospace industry, wireless technology industry, academia, research institutions, and end-users to do the following: (1...

  4. Short Communications A re-evaluation of the taxonomic status of ...

    1990-06-05

    Jun 5, 1990 ... X. b. var. linea/US. Roux, 1907 was found to differ sufficiently from typical bieolor to allow subspecific status (FitzSimons 1946). In. 1915, Werner described Micaela pernasUla, later placed in the genus Xenoealamus by Hewitt (1926) and treated as X. b. pernasutus by FitzSimons (1946; 1962) and Witte &.

  5. Communication constraints, indexical countermeasures, and crew configuration effects in simulated space-dwelling groups

    Hienz, Robert D.; Brady, Joseph V.; Hursh, Steven R.; Banner, Michele J.; Gasior, Eric D.; Spence, Kevin R.

    2007-02-01

    Previous research with groups of individually isolated crews communicating and problem-solving in a distributed interactive simulation environment has shown that the functional interchangeability of available communication channels can serve as an effective countermeasure to communication constraints. The present report extends these findings by investigating crew performance effects and psychosocial adaptation following: (1) the loss of all communication channels, and (2) changes in crew configuration. Three-person crews participated in a simulated planetary exploration mission that required identification, collection, and analysis of geologic samples. Results showed that crews developed and employed discrete navigation system operations that served as functionally effective communication signals (i.e., “indexical” or “deictic” cues) in generating appropriate crewmember responses and maintaining performance effectiveness in the absence of normal communication channels. Additionally, changes in crew configuration impacted both performance effectiveness and psychosocial adaptation.

  6. The Analysis and suggested marketing communication for CleanMySpace start-up company

    Tolstykh, Anastasiia

    2016-01-01

    This bachelor thesis is focused on the proposal of marketing communication for new start-up company CleanMyPlace, the winner of VŠE Exports 2015, aimed at increase of its brand awareness and improvement of existing marketing strategies and tactics. The theoretical part is devoted to marketing tools, most improtantly to marketing online communication, as soon as this brand provides its services via internet. In the practical part are defined and analysed the current marketing communication. Th...

  7. Satellite and Ground Communication Systems: Space and Electronic Warfare Threats to the United States Army

    2017-02-01

    as if SATCOM is guaranteed. This complacency is accompanied by the procurement of high-data communication and mission command systems that deny...threat. To overcome these significant vulnerabilities, the US Army must procure communications systems that maintain the information high ground, but...precious gift of our freedom.”1 A key element of remaining strong on the ground is maintaining the capability to effectively communicate on the ground. If

  8. Status and development trends of the National Space Monitoring System of the Republic of Kazakhstan

    Sultangazin, U.M.; Spivak, L.F.

    2005-01-01

    Principles of construction and architecture of space monitoring of Kazakhstan are presented, structure and specifications of space and ground segments are described, top-priority tasks of monitoring are determined. (author)

  9. Status and plans of NASA's Materials Science and Manufacturing in Space (MS/MS) program

    Armstrong, W. O.; Bredt, J. H.

    1972-01-01

    A description is given of a research and development program on the space shuttle mission designed to prepare the way for possible commercial manufacturing operations on permanently orbiting space stations.

  10. Adaptive Space-Time, Processing for High Performance, Robust Military Wireless Communications

    Haimovich, Alexander

    2000-01-01

    ...: (I) performance of adaptive arrays for wireless communications over fading channels in the presence of cochannel interference particularly the case when the number of interference sources exceeds...

  11. BER Analysis of Coherent Free-Space Optical Communication Systems with a Focal-Plane-Based Wavefront Sensor

    Cao, Jingtai; Zhao, Xiaohui; Liu, Wei; Gu, Haijun

    2018-03-01

    A wavefront sensor is one of most important units for an adaptive optics system. Based on our previous works, in this paper, we discuss the bit-error-rate (BER) performance of coherent free space optical communication systems with a focal-plane-based wavefront sensor. Firstly, the theory of a focal-plane-based wavefront sensor is given. Then the relationship between the BER and the mixing efficiency with a homodyne receiver is discussed on the basis of binary-phase-shift-keying (BPSK) modulation. Finally, the numerical simulation results are shown that the BER will be decreased obviously after aberrations correction with the focal-plane-based wavefront sensor. In addition, the BER will decrease along with increasing number of photons received within a single bit. These analysis results will provide a reference for the design of the coherent Free space optical communication (FSOC) system.

  12. Husband-wife communication and status of women as a determinant of contraceptive use in rural Bangladesh.

    Kabir, M; Moslehuddin, M; Howlader, A A

    1988-03-01

    The study provides the socioeconomic status of women and factors which affect their choice of contraception using data collected from 423 working women in the Savan Upazila, Bangladesh. 72% of the sample included women under 30 years old, and 53% of the sample and attended primary school and were equal to their husbands educationally. 46.1% were employed in the garment industry, 13.8% in construction, 14/45% in services, and 17% in farm or hand craft activities. 80% lived in rural areas and did not own land. 600% were from a nuclear family. The average husband's income was Taka 1501. 18% had an affiliation with some organization. 42% were using contraceptives, and 58% discussed use of family planning (FP). 66% shared decision making with their husbands about their children's education and marriage. Logistic analysis is used to determine the probability of contraceptive use on the following independent variables: age, wife's education, membership in a society, contract with FP workers, participation in income-generating activities, visit of FP workers, visit of health workers, family type, husband's education and monthly income, and ownership of electricity. The results indicate that women working outside the house have improved their status in the family and the community, and this more equal status and the presence of good husband and wife communication are intervening variables through which economic and demographic factors effect fertility. Contract with FP workers was very closely related to use of contraceptives.

  13. Performance improvement of coherent free-space optical communication with quadrature phase-shift keying modulation using digital phase estimation.

    Li, Xueliang; Geng, Tianwen; Ma, Shuang; Li, Yatian; Gao, Shijie; Wu, Zhiyong

    2017-06-01

    The performance of coherent free-space optical (CFSO) communication with phase modulation is limited by both phase fluctuations and intensity scintillations induced by atmospheric turbulence. To improve the system performance, one effective way is to use digital phase estimation. In this paper, a CFSO communication system with quadrature phase-shift keying modulation is studied. With consideration of the effects of log-normal amplitude fluctuations and Gauss phase fluctuations, a two-stage Mth power carrier phase estimation (CPE) scheme is proposed. The simulation results show that the phase noise can be suppressed greatly by this scheme, and the system symbol error rate performance with the two-stage Mth power CPE can be three orders lower than that of the single-stage Mth power CPE. Therefore, the two-stage CPE we proposed can contribute to the performance improvements of the CFSO communication system and has determinate guidance sense to its actual application.

  14. Stress of Rescue Team Members Working in Confined Spaces During a Disaster : Effectiveness of Individual Wireless Communication Devices

    Kitabayashi, Tsukasa; Kudo, Seiko; Kitajima, Maiko; Takamaki, Shizuka; Chiba, Tomohiro; Tachioka, Nobuaki; Kudo, Shungetsu; Kudo, Hiromi

    2016-01-01

    This study evaluated stress experienced by rescue team members during a simulated search and rescue operation in a confined space and determine if wireless communication reduces stress. A total of 57 rescue team members of X prefecture participated. The stress visualization indices were ptyalin (i.e., salivary amylase), salivary cortisol, autonomic nervous system response, visual analog scale, and a short version of the profile of mood states. The subjects were randomized to perform a simulat...

  15. Iron status and its relations with oxidative damage and bone loss during long-duration space flight on the International Space Station.

    Zwart, Sara R; Morgan, Jennifer L L; Smith, Scott M

    2013-07-01

    Increases in stored iron and dietary intake of iron during space flight have raised concern about the risk of excess iron and oxidative damage, particularly in bone. The objectives of this study were to perform a comprehensive assessment of iron status in men and women before, during, and after long-duration space flight and to quantify the association of iron status with oxidative damage and bone loss. Fasting blood and 24-h urine samples were collected from 23 crew members before, during, and after missions lasting 50 to 247 d to the International Space Station. Serum ferritin and body iron increased early in flight, and transferrin and transferrin receptors decreased later, which indicated that early increases in body iron stores occurred through the mobilization of iron to storage tissues. Acute phase proteins indicated no evidence of an inflammatory response during flight. Serum ferritin was positively correlated with the oxidative damage markers 8-hydroxy-2'-deoxyguanosine (r = 0.53, P < 0.001) and prostaglandin F2α (r = 0.26, P < 0.001), and the greater the area under the curve for ferritin during flight, the greater the decrease in bone mineral density in the total hip (P = 0.031), trochanter (P = 0.006), hip neck (P = 0.044), and pelvis (P = 0.049) after flight. Increased iron stores may be a risk factor for oxidative damage and bone resorption.

  16. Vehicle to Grid Communication Standards Development, Testing and Validation - Status Report

    Gowri, Krishnan; Pratt, Richard M.; Tuffner, Francis K.; Kintner-Meyer, Michael CW

    2011-09-01

    In the US, more than 10,000 electric vehicles (EV) have been delivered to consumers during the first three quarters of 2011. A large majority of these vehicles are battery electric, often requiring 220 volt charging. Though the vehicle manufacturers and charging station manufacturers have provided consumers options for charging preferences, there are no existing communications between consumers and the utilities to manage the charging demand. There is also wide variation between manufacturers in their approach to support vehicle charging. There are in-vehicle networks, charging station networks, utility networks each using either cellular, Wi-Fi, ZigBee or other proprietary communication technology with no standards currently available for interoperability. The current situation of ad-hoc solutions is a major barrier to the wide adoption of electric vehicles. SAE, the International Standards Organization/International Electrotechnical Commission (ISO/IEC), ANSI, National Institute of Standards and Technology (NIST) and several industrial organizations are working towards the development of interoperability standards. PNNL has participated in the development and testing of these standards in an effort to accelerate the adoption and development of communication modules.

  17. Recent advances in high-capacity free-space optical and radio-frequency communications using orbital angular momentum multiplexing

    Ren, Yongxiong; Xie, Guodong; Yan, Yan; Li, Long; Zhao, Zhe; Wang, Jian; Tur, Moshe; Molisch, Andreas F.; Ashrafi, Solyman

    2017-01-01

    There is a continuing growth in the demand for data bandwidth, and the multiplexing of multiple independent data streams has the potential to provide the needed data capacity. One technique uses the spatial domain of an electromagnetic (EM) wave, and space division multiplexing (SDM) has become increasingly important for increased transmission capacity and spectral efficiency of a communication system. A subset of SDM is mode division multiplexing (MDM), in which multiple orthogonal beams each on a different mode can be multiplexed. A potential modal basis set to achieve MDM is to use orbital angular momentum (OAM) of EM waves. In such a system, multiple OAM beams each carrying an independent data stream are multiplexed at the transmitter, propagate through a common medium and are demultiplexed at the receiver. As a result, the total capacity and spectral efficiency of the communication system can be multiplied by a factor equal to the number of transmitted OAM modes. Over the past few years, progress has been made in understanding the advantages and limitations of using multiplexed OAM beams for communication systems. In this review paper, we highlight recent advances in the use of OAM multiplexing for high-capacity free-space optical and millimetre-wave communications. We discuss different technical challenges (e.g. atmospheric turbulence and crosstalk) as well as potential techniques to mitigate such degrading effects. This article is part of the themed issue ‘Optical orbital angular momentum’. PMID:28069770

  18. High-dimensional structured light coding/decoding for free-space optical communications free of obstructions.

    Du, Jing; Wang, Jian

    2015-11-01

    Bessel beams carrying orbital angular momentum (OAM) with helical phase fronts exp(ilφ)(l=0;±1;±2;…), where φ is the azimuthal angle and l corresponds to the topological number, are orthogonal with each other. This feature of Bessel beams provides a new dimension to code/decode data information on the OAM state of light, and the theoretical infinity of topological number enables possible high-dimensional structured light coding/decoding for free-space optical communications. Moreover, Bessel beams are nondiffracting beams having the ability to recover by themselves in the face of obstructions, which is important for free-space optical communications relying on line-of-sight operation. By utilizing the OAM and nondiffracting characteristics of Bessel beams, we experimentally demonstrate 12 m distance obstruction-free optical m-ary coding/decoding using visible Bessel beams in a free-space optical communication system. We also study the bit error rate (BER) performance of hexadecimal and 32-ary coding/decoding based on Bessel beams with different topological numbers. After receiving 500 symbols at the receiver side, a zero BER of hexadecimal coding/decoding is observed when the obstruction is placed along the propagation path of light.

  19. Level crossing statistics for optical beam wander in a turbulent atmosphere with applications to ground-to-space laser communications.

    Yura, Harold T; Fields, Renny A

    2011-06-20

    Level crossing statistics is applied to the complex problem of atmospheric turbulence-induced beam wander for laser propagation from ground to space. A comprehensive estimate of the single-axis wander angle temporal autocorrelation function and the corresponding power spectrum is used to develop, for the first time to our knowledge, analytic expressions for the mean angular level crossing rate and the mean duration of such crossings. These results are based on an extension and generalization of a previous seminal analysis of the beam wander variance by Klyatskin and Kon. In the geometrical optics limit, we obtain an expression for the beam wander variance that is valid for both an arbitrarily shaped initial beam profile and transmitting aperture. It is shown that beam wander can disrupt bidirectional ground-to-space laser communication systems whose small apertures do not require adaptive optics to deliver uniform beams at their intended target receivers in space. The magnitude and rate of beam wander is estimated for turbulence profiles enveloping some practical laser communication deployment options and suggesting what level of beam wander effects must be mitigated to demonstrate effective bidirectional laser communication systems.

  20. The role of augmentative and alternative communication for children with autism: current status and future trends

    Iacono T

    2016-09-01

    Full Text Available Teresa Iacono,1 David Trembath,2 Shane Erickson3 1Living with Disability Research Centre, La Trobe University, Bendigo, VIC, Australia; 2Menzies Health Institute Queensland, Griffith University, Gold Coast, QLD, Australia; 3Living with Disability Research Centre, La Trobe University, Melbourne, VIC, Australia Background: Augmentative and alternative communication (AAC interventions are used for children with autism, often as stand-alone communication interventions for those who are minimally verbal. Our aim was to synthesize the evidence for AAC interventions for children (up to 21 years, and then consider the role of AAC within established, comprehensive, evidence-based autism interventions targeting learning across multiple developmental domains.Design: We completed a systematic search of three databases (OVID Medline, PsycINFO, ERIC as well as forward citation and hand searches to identify systematic reviews of AAC intervention efficacy research including children with autism, published between 2000 and March 2016 in peer-reviewed journals. Data pertaining to the quality indicators of included studies, effect sizes for intervention outcomes, and evidence for effectiveness were extracted for descriptive analysis.Results: The search yielded 17 systematic reviews. Most provided indicators of research quality for included studies, of which only relatively few provided conclusive results. Communication targets tended to be focused on teaching children to make requests. Still, effect size measures for included studies indicated that AAC was effective to highly effective.Conclusion: There is growing evidence for the potential benefits of AAC for children with autism, but there is a need for more well-designed studies and broader, targeted outcomes. Furthermore, a lack of evidence for the role of AAC within comprehensive intervention programs may account for a tendency by autism researchers and practitioners to neglect this intervention. Attempts to

  1. Patient-Physician Communication About Code Status Preferences: A Randomized Controlled Trial

    Rhondali, Wadih; Perez-Cruz, Pedro; Hui, David; Chisholm, Gary B.; Dalal, Shalini; Baile, Walter; Chittenden, Eva; Bruera, Eduardo

    2013-01-01

    Purpose Code status discussions are important in cancer care. The best modality for such discussions has not been established. Our objective was to determine the impact of a physician ending a code status discussion with a question (autonomy approach) versus a recommendation (beneficence approach) on patients' do-not-resuscitate (DNR) preference. Methods Patients in a supportive care clinic watched two videos showing a physician-patient discussion regarding code status. Both videos were identical except for the ending: one ended with the physician asking for the patient's code status preference and the other with the physician recommending DNR. Patients were randomly assigned to watch the videos in different sequences. The main outcome was the proportion of patients choosing DNR for the video patient. Results 78 patients completed the study. 74% chose DNR after the question video, 73% after the recommendation video. Median physician compassion score was very high and not different for both videos. 30/30 patients who had chosen DNR for themselves and 30/48 patients who had not chosen DNR for themselves chose DNR for the video patient (100% v/s 62%). Age (OR=1.1/year) and white ethnicity (OR=9.43) predicted DNR choice for the video patient. Conclusion Ending DNR discussions with a question or a recommendation did not impact DNR choice or perception of physician compassion. Therefore, both approaches are clinically appropriate. All patients who chose DNR for themselves and most patients who did not choose DNR for themselves chose DNR for the video patient. Age and race predicted DNR choice. PMID:23564395

  2. The Process of Science Communications at NASA/Marshall Space Flight Center

    Horack, John M.; Treise, Deborah

    1998-01-01

    The communication of new scientific knowledge and understanding is an integral component of science research, essential for its continued survival. Like any learning-based activity, science cannot continue without communication between and among peers so that skeptical inquiry and learning can take place. This communication provides necessary organic support to maintain the development of new knowledge and technology. However, communication beyond the peer-community is becoming equally critical for science to survive as an enterprise into the 21st century. Therefore, scientists not only have a 'noble responsibility' to advance and communicate scientific knowledge and understanding to audiences within and beyond the peer-community, but their fulfillment of this responsibility is necessary to maintain the survival of the science enterprise. Despite the critical importance of communication to the viability of science, the skills required to perform effective science communications historically have not been taught as a part of the training of scientist, and the culture of science is often averse to significant communication beyond the peer community. Thus scientists can find themselves ill equipped and uncomfortable with the requirements of their job in the new millennium.

  3. MF-CRA: Multi-Function Cognitive Radio Architecture for Space Communications, Phase I

    National Aeronautics and Space Administration — EpiSys Science, Inc. and University of Arizona propose to develop, implement, and demonstrate Multi-Function Cognitive Radio Architecture (MF-CRA) for Space...

  4. Entanglement-assisted Communication System for NASA's Deep-Space Missions: Feasibility Test and Conceptual Design

    National Aeronautics and Space Administration — This project is involved with transferring information through the vast distances of space. The challenge is that it is difficult to get many photons from a...

  5. Study of Lateral Misalignment Tolerance of a Symmetric Free-Space Optical Link for Intra International Space Station Communication

    Tedder, Sarah; Schoenholz, Bryan; Suddath, Shannon

    2016-01-01

    This paper describes the study of lateral misalignment tolerance of a symmetric high-rate free-space optical link (FSOL) for use between International Space Station (ISS) payload sites and the main cabin. The link will enable gigabit per second (Gbps) transmission of data, which is up to three orders of magnitude greater than the current capabilities. This application includes 10-20 meter links and requires minimum size, weight, and power (SWaP). The optical power must not present an eye hazard and must be easily integrated into the existing ISS infrastructure. On the ISS, rapid thermal changes and astronaut movement will cause flexure of the structure which will potentially misalign the free space transmit and receive optics 9 cm laterally and 0.2 degrees angularly. If this misalignment is not accounted for, a loss of the link or degradation of link performance will occur. Power measurements were collected to better understand the effect of various system design parameters on lateral misalignment. Parameters that were varied include: the type of small form pluggable (SFP) transceivers, type of fiber, and transmitted power level. A potential solution was identified that can reach the lateral misalignment tolerance (decenter span) required to create an FSOL on the ISS by using 105 m core fibers, a duplex SFP, two channels of light, and two fiber amplifiers.

  6. Research on the method of measuring space information network capacity in communication service

    Zhu Shichao

    2017-02-01

    Full Text Available Because of the large scale characteristic of space information network in terms of space and time and the increasing of its complexity,existing measuring methods of information transmission capacity have been unable to measure the existing and future space information networkeffectively.In this study,we firstly established a complex model of space information network,and measured the whole space information network capacity by means of analyzing data access capability to the network and data transmission capability within the network.At last,we verified the rationality of the proposed measuring method by using STK and Matlab simulation software for collaborative simulation.

  7. An overview of Space Communication Artificial Intelligence for Link Evaluation Terminal (SCAILET) Project

    Shahidi, Anoosh K.; Schlegelmilch, Richard F.; Petrik, Edward J.; Walters, Jerry L.

    1991-11-01

    A software application to assist end-users of the link evaluation terminal (LET) for satellite communications is being developed. This software application incorporates artificial intelligence (AI) techniques and will be deployed as an interface to LET. The high burst rate (HBR) LET provides 30 GHz transmitting/20 GHz receiving (220/110 Mbps) capability for wideband communications technology experiments with the Advanced Communications Technology Satellite (ACTS). The HBR LET can monitor and evaluate the integrity of the HBR communications uplink and downlink to the ACTS satellite. The uplink HBR transmission is performed by bursting the bit-pattern as a modulated signal to the satellite. The HBR LET can determine the bit error rate (BER) under various atmospheric conditions by comparing the transmitted bit pattern with the received bit pattern. An algorithm for power augmentation will be applied to enhance the system's BER performance at reduced signal strength caused by adverse conditions.

  8. A Secure and Efficient Communications Architecture for Global Information Grid Users Via Cooperating Space Assets

    Hubenko, Jr, Victor P

    2008-01-01

    With the Information Age in full and rapid development, users expect to have global, seamless, ubiquitous, secure, and efficient communications capable of providing access to real-time applications and collaboration...

  9. Algebraic Approaches to Space-Time Code Construction for Multiple-Antenna Communication

    Raviteja, U; Sharanappa, I; Vanamali, B; Kumar, Vijay P

    2011-01-01

    A major challenge in wireless communications is overcoming the deleterious effects of fading, a phenomenon largely responsible for the seemingly inevitable dropped call. Multiple-antennas communication systems, commonly referred to as MIMO systems, employ multiple antennas at both transmitter and receiver, thereby creating a multitude of signalling pathways between transmitter and receiver. These multiple pathways give the signal a diversity advantage with which to combat fading. Apart fro...

  10. Multi-Aperture Digital Coherent Combining for Free-Space Optical Communication Receivers

    2016-04-21

    emulated by a cascade of fiber beam splitters . Fig. 4(a) depicts the transmitter, which consisted of two cascaded Mach- Zehnder modulators (MZMs) that...Sons, Inc., Hoboken, New Jersey, 2006). 5. D. O. Caplan, "Laser communication transmitter and receiver design ," J. Opt. Fiber. Commun. 4(4-5), 225...and A. E. Willner, eds. (Elsevier, 2013). 7. S. B. Alexander, Optical Communication Receiver Design (SPIE, 1997). 8. D. M. Boroson, "A survey of

  11. Asynchronous Free-Space Optical CDMA Communications System for Last-mile Access Network

    Jurado-Navas, Antonio; Raddo, Thiago R.; Sanches, Anderson L.

    2016-01-01

    We propose a new hybrid asynchronous OCDMA-FSO communications system for access network solutions. New ABER expressions are derived under gamma-gamma scintillation channels, where all users can surprisingly achieve error-free transmissions when FEC is employed.......We propose a new hybrid asynchronous OCDMA-FSO communications system for access network solutions. New ABER expressions are derived under gamma-gamma scintillation channels, where all users can surprisingly achieve error-free transmissions when FEC is employed....

  12. High-Rate Laser Communications for Human Exploration and Science

    Robinson, B. S.; Shih, T.; Khatri, F. I.; King, T.; Seas, A.

    2018-02-01

    Laser communication links has been successfully demonstrated on recent near-Earth and lunar missions. We present a status of this development work and its relevance to a future Deep Space Gateway supporting human exploration and science activities.

  13. Creating a "Third Space" in Student Teaching: Implications for the University Supervisor's Status as Outsider

    Cuenca, Alexander; Schmeichel, Mardi; Butler, Brandon M.; Dinkelman, Todd; Nichols, Joseph R., Jr.

    2011-01-01

    The work of teacher education during student teaching typically takes place in two distinct "spaces": placement sites and college/university settings. The program featured in this article is structured in ways that clearly mark out those two spaces. Yet this configuration led our university supervisors, whose work primarily took place in the…

  14. Interference Analysis Status and Plans for Aeronautical Mobile Airport Communications System (AeroMACS)

    Kerczewski, Robert J.; Wilson, Jeffrey D.

    2010-01-01

    Interference issues related to the operation of an aeronautical mobile airport communications system (AeroMACS) in the C-Band (specifically 5091-5150 MHz) is being investigated. The issue of primary interest is co-channel interference from AeroMACS into mobile-satellite system (MSS) feeder uplinks. The effort is focusing on establishing practical limits on AeroMACS transmissions from airports so that the threshold of interference into MSS is not exceeded. The analyses are being performed with the software package Visualyse Professional, developed by Transfinite Systems Limited. Results with omni-directional antennas and plans to extend the models to represent AeroMACS more accurately will be presented. These models should enable realistic analyses of emerging AeroMACS designs to be developed from NASA Test Bed, RTCA 223, and European results.

  15. COMMUNICATIONS

    L. Taylor and D. Barney

    2010-01-01

    CMS Centres, Outreach and the 7 TeV Media Event The new CMS Communications group is now established and is addressing three areas that are critical to CMS as it enters the physics operations phase: - Communications Infrastructure, including almost 50 CMS Centres Worldwide, videoconferencing systems, and CERN meeting rooms - Information systems, including the internal and external Web sites as well as the document preparation and management systems - Outreach and Education activities, including working with print, radio and TV media, visits to CMS, and exhibitions. The group has been active in many areas, with the highest priority being accorded to needs of CMS operations and preparations for the major media event planned for 7 TeV collisions. Unfortunately the CMS Centre@CERN suffered a major setback when, on 21st December, a cooling water pipe froze and burst on the floor above the CMS Centre main room. Water poured through the ceiling, flooding the floor and soaking some of the consoles, before e...

  16. COMMUNICATIONS

    A. Petrilli

    2013-01-01

    The organisation of the Open Days at the end of September was the single biggest effort of the CMS Communications Group this year. We would like to thank all volunteers for their hard work to show our Point 5 facilities and explain science and technology to the general public. During two days more than 5,000 people visited the CMS detector underground and profited from the surface activities, which included an exhibition on CMS, a workshop on superconductivity, and an activity for our younger visitors involving wooden Kapla blocks. The Communications Group took advantage of the preparations to produce new CMS posters that can be reused at other venues. Event display images have been produced not just for this occasion but also for other exhibits, education purposes, publications etc. During the Open Days, Gilles Jobin, 2012 winner of CERN Collide@CERN prize, performed his Quantum show in Point 5, with the light installation of German artist Julius von Bismarck. Image 3: CERN Open Days at CMS wel...

  17. Selection of a Data Acquisition and Controls System Communications and Software Architecture for Johnson Space Center's Space Environment Simulation Laboratory Thermal and Vacuum Test Facilities

    Jordan, Eric A.

    2004-01-01

    Upgrade of data acquisition and controls systems software at Johnson Space Center's Space Environment Simulation Laboratory (SESL) involved the definition, evaluation and selection of a system communication architecture and software components. A brief discussion of the background of the SESL and its data acquisition and controls systems provides a context for discussion of the requirements for each selection. Further framework is provided as upgrades to these systems accomplished in the 1990s and in 2003 are compared to demonstrate the role that technological advances have had in their improvement. Both of the selections were similar in their three phases; 1) definition of requirements, 2) identification of candidate products and their evaluation and testing and 3) selection by comparison of requirement fulfillment. The candidates for the communication architecture selection embraced several different methodologies which are explained and contrasted. Requirements for this selection are presented and the selection process is described. Several candidates for the software component of the data acquisition and controls system are identified, requirements for evaluation and selection are presented, and the evaluation process is described.

  18. Importance of Women's Relative Socioeconomic Status within Sexual Relationships in Communication about Safer Sex and HIV/STI Prevention.

    Muchomba, Felix M; Chan, Christine; El-Bassel, Nabila

    2015-06-01

    The socioeconomic status (SES) of women is increasingly considered an important factor for HIV/STI risk. The HIV/STI literature has largely focused on women's absolute levels of SES, and therefore, the importance of their SES relative to their male sexual partners remains understudied. This paper examines the association between women's relative SES and frequency of safer sex communication among heterosexual couples. A convenience sample of 342 couples (N = 684) recruited in New York City was asked about frequency of discussions with their partner about the need to use male condoms, about HIV prevention, and about STI prevention in the previous 90 days. Differences between partners in education, income, employment, housing, and incarceration history were combined using principal component analysis to form an index of women's relative SES. Negative binomial regression models assessed associations between woman's relative SES and communication frequency controlling for age, sex, race, ethnicity, education, and relationship type using a generalized estimating equation framework. On average, participants had 2.5, 4.2, and 4.8 discussions regarding the need to use male condoms, about HIV prevention, and about STI prevention, respectively. A one standard deviation increase in a woman's relative SES score was associated with increased frequency of discussions about male condom use (adjusted rate ratio [aRR], 1.15; 95% confidence interval [CI], 1.03-1.29), about HIV prevention (aRR, 1.25; CI, 1.14-1.37), and about STI prevention (aRR, 1.29; CI, 1.18-1.41). Women's relative SES may be an important factor for sexual communication, and further research on its role in HIV/STI risk may uncover avenues for intervention.

  19. The health status of grandchildren of subjects occupationally exposed to chronic radiation. Communication 2. Morphofunctional parameters

    Petrushkina, N.P.; Musatkova, O.B.

    1996-01-01

    The study was aimed at investigation of the parameters of physical development and specific features in the development of psychomotor habits and peripheral blood parameters in children aged 0 to 7 grandchildren of exposed individuals. A dynamic follow-up of physical and psychomotor development, as well as regular check-ups of peripheral blood were carried out in 877 grandchildren of test subjects occupationally exposed to chronic radiation before conception. Multifactorial analysis did not show a correlation between the deviations in the physical development of children in the studied cohort and exposure of their grandparents and/or parents. Factors other than radiation (poor health status of mother, gestosis) did influence the studied parameters. The mean levels of hemoglobin, red cells, platelets, and leukocytes in the test group were virtually the same as in controls and coincided with published data [ru

  20. Impact of communication delays to and from the International Space Station on self-reported individual and team behavior and performance: A mixed-methods study

    Kintz, Natalie M.; Chou, Chih-Ping; Vessey, William B.; Leveton, Lauren B.; Palinkas, Lawrence A.

    2016-12-01

    Deep space explorations will involve significant delays in communication to and from Earth that will likely impact individual and team outcomes. However, the extent of these impacts and the appropriate countermeasures for their mitigation remain largely unknown. This study utilized the International Space Station (ISS), a high-fidelity analog for deep space, as a research platform to assess the impact of communication delays on individual and team performance, mood, and behavior. Three astronauts on the ISS and 18 mission support personnel performed tasks with and without communication delays (50-s one-way) during a mission lasting 166 days. Self-reported assessments of individual and team performance and mood were obtained after each task. Secondary outcomes included communication quality and task autonomy. Qualitative data from post-mission interviews with astronauts were used to validate and expand on quantitative data, and to elicit recommendations for countermeasures. Crew well-being and communication quality were significantly reduced in communication delay tasks compared to control. Communication delays were also significantly associated with increased individual stress/frustration. Qualitative data suggest communication delays impacted operational outcomes (i.e. task efficiency), teamwork processes (i.e. team/task coordination) and mood (i.e. stress/frustration), particularly when tasks involved high task-related communication demands, either because of poor communication strategies or low crew autonomy. Training, teamwork, and technology-focused countermeasures were identified to mitigate or prevent adverse impacts.

  1. Low-Noise Free-Running High-Rate Photon-Counting for Space Communication and Ranging

    Lu, Wei; Krainak, Michael A.; Yang, Guan; Sun, Xiaoli; Merritt, Scott

    2016-01-01

    We present performance data for low-noise free-running high-rate photon counting method for space optical communication and ranging. NASA GSFC is testing the performance of two types of novel photon-counting detectors 1) a 2x8 mercury cadmium telluride (HgCdTe) avalanche array made by DRS Inc., and a 2) a commercial 2880-element silicon avalanche photodiode (APD) array. We successfully measured real-time communication performance using both the 2 detected-photon threshold and logic AND-gate coincidence methods. Use of these methods allows mitigation of dark count, after-pulsing and background noise effects without using other method of Time Gating The HgCdTe APD array routinely demonstrated very high photon detection efficiencies (50) at near infrared wavelength. The commercial silicon APD array exhibited a fast output with rise times of 300 ps and pulse widths of 600 ps. On-chip individually filtered signals from the entire array were multiplexed onto a single fast output. NASA GSFC has tested both detectors for their potential application for space communications and ranging. We developed and compare their performances using both the 2 detected photon threshold and coincidence methods.

  2. Space-Time Equalization for High-Speed Wireless Digital Communications Based on Multipath-Incorporating Matched Filtering, Zero Forcing Equalization, and MMSE

    Zoltowski, Michael D

    2003-01-01

    The project has successfully demonstrated reduced-rank, space-time equalization for high-speed wireless digital communications capable of reliably transmitting multimedia data in support of military...

  3. Aperture Averaging of Scintillation for Space-to-Ground Optical Communication Applications.

    1983-08-15

    SCINTILLATION FOR SPACE-TO-GROUND OPTICAL COMUNICATION APPLICATIONS ........................ 5 REFERENCES...theoretical investigations necessary for the evaluation and applica- tion of scientific advances to now military space systems. Versatility and flexibility...systems. Expertise in the latest scientific developments is vital to the accomplishment of tasks related to these problems. The laboratories that con

  4. Communicative competences in Experimental Sciences degrees within the framework of the new European Space for Higher Education

    Joseba Ezeiza Ramos

    2009-10-01

    Full Text Available The scenario for developing communicative competences in the Experimental Sciences degrees and within the new European Space for Higher Education is highly complex. This is confirmed by research reported in the White Papers on the new degrees in this subject area. Therefore, to smoothly integrate communicative and linguistic competences into future syllabi, I should first make a careful analysis of the main factors at work in the new situation. This paper seeks to provide a preliminary approach to the problem. First, I describe the academic and professional tasks that constitute the objectives of future European science degrees. This is followed by an analysis of the communicative and linguistic parameters considered essential for satisfactory attainment of these objectives. Finally, the specific skills that students must master in order to meet the demands imposed by the new framework are outlined. The results of this analysis will enable us to see how much the new situation differs from traditional university teaching. Under this new model, the development of communicative and linguistic competences will no longer be a mere adjunct to a science curriculum, but instead will become of prime importance to the academic and professional training of future scientists.

  5. The performance of orthogonal frequency division multiplexing in the weak turbulence regime of free space optics communication systems

    Selvi, M; Murugesan, K

    2012-01-01

    Radio on free space optics—RoFSO—has gained momentum in research because of its cost effectiveness and efficiency in transferring data at a high rate that is comparable to that for optical fiber media. While the transmission data rate is limited in fiber due to dispersion and nonlinearity, such effects do not prevail in FSO communication links. The data rate depends mainly on the switching speed of the optoelectronic devices. With the characteristics of free space being random in nature, the performance of RoFSO is primarily governed by atmospheric conditions. In this paper, we evaluate the performance of the orthogonal frequency division multiplexing (OFDM) signal in free space and compare against its counterpart radio frequency (RF) wireless communication systems. Simulations have been done on the atmospheric conditions by means of modeling the scintillation effect using log-normal distribution. The performance of the proposed system under two different base-band modulations, namely OFDM–PSK (phase shift keying) and QAM (quadrature amplitude modulation) in weak turbulence conditions is studied. It is found that PSK performs better than QAM. Also the M-ary performance analysis shows that 3–5 dB improvement in the signal to noise ratio is obtained for OFDM based FSO transmission compared to RF based wireless transmission. (paper)

  6. Distracted: Academic Performance Differences between Teen Users and Non-Users of MySpace and other Communication Technology

    Tamyra A. Pierce

    2008-06-01

    Full Text Available This study examined the differences in academic performance between teen users and non-users of various communication technologies. Participants included 517 high school students who completed a self-report survey. The results revealed that approximately 3/4 of the teens had a MySpace account and a cell phone and more than 1/2 had an IM account. Results also showed that those who had a MySpace account, cell phone and IM had signifi cantly lower grades than those who did not. Results also revealed that teens who used their MySpace, cell phone and IM while doing their homework reported having lower grades than those who did not use the technology while doing their homework. In addition, those who put off doing their homework to spend time on MySpace also reported lower grades than those who did not put off doing their homework to spend time with MySpace. Finally, results showed that 28% text messaged during class from always to frequently, and 5% reported text messaging during an exam from always to frequently.

  7. Final Report: 03-LW-005 Space-Time Secure Communications for Hostile Environments

    Candy, J V; Poggio, A J; Chambers, D H; Guidry, B L; Robbins, C L; Hertzog, C A; Dowla, F; Burke, G; Kane, R

    2005-10-31

    The development of communications for highly reverberative environments is a major concern for both the private and military sectors whether the application is aimed at the securing a stock order or stalking hostile in a tunnel or cave. Other such environments can range from a hostile urban setting populated with a multitude of buildings and vehicles to the simple complexity of a large number of sound sources that are common in the stock exchange, or military operations in an environment with a topographic features hills, valleys, mountains or even a maze of buried water pipes attempting to transmit information about any chemical anomalies in the water system servicing a city or town. These inherent obstructions cause transmitted signals to reflect, refract and disperse in a multitude of directions distorting both their shape and arrival times at network receiver locations. Imagine troops attempting to communicate on missions in underground caves consisting of a maze of chambers causing multiple echoes with the platoon leader trying to issue timely commands to neutralize terrorists. This is the problem with transmitting information in a complex environment. Waves are susceptible to multiple paths and distortions created by a variety of possible obstructions, which may exist in the particular propagation medium. This is precisely the communications problem we solve using the physics of wave propagation to not only mitigate the noxious effects created by the hostile medium, but also to utilize it in a constructive manner enabling a huge benefit in communications. We employ time-reversal (T/R) communications to accomplish this task. This project is concerned with the development of secure communications techniques that can operate even in the most extreme conditions while maintaining a secure link between host and client stations. We developed an approach based on the concept of time-reversal (T/R) signal processing. In fact, the development of T/R communication

  8. Modelling of 10 Gbps Free Space Optics Communication Link Using Array of Receivers in Moderate and Harsh Weather Conditions

    Gupta, Amit; Shaina, Nagpal

    2017-08-01

    Intersymbol interference and attenuation of signal are two major parameters affecting the quality of transmission in Free Space Optical (FSO) Communication link. In this paper, the impact of these parameters on FSO communication link is analysed for delivering high-quality data transmission. The performance of the link is investigated under the influence of amplifier in the link. The performance parameters of the link like minimum bit error rate, received signal power and Quality factor are examined by employing erbium-doped fibre amplifier in the link. The effects of amplifier are visualized with the amount of received power. Further, the link is simulated for moderate weather conditions at various attenuation levels on transmitted signal. Finally, the designed link is analysed in adverse weather conditions by using high-power laser source for optimum performance.

  9. Information transfer among widely spaced individuals: latrines as a basis for communication networks in the swift fox

    Darden, Safi-Kirstine; Steffensen, Lise K.; Dabelsteen, Torben

    2008-01-01

    In species where individuals are widely spaced instantaneous signals cannot readily form the basis of communication networks, that is several individuals within signalling range of each other. However, markings, signals that remain in the environment after the signaller has left, may fulfil...... this role. In this study, we have investigated the possible function of swift fox, Vulpes velox, latrines, collections of scat, urine and possibly other secretions, in a communication network context. We found that latrines had higher frequencies of occurrence inside the core (defined as the 50% kernel...... contour) of a pair's home-range when compared with outside the core and in areas of a pair's home-range that overlapped with neighbouring individuals when compared with those areas that did not overlap with neighbours. These were also the two areas where latrines were most likely to reoccur in the next...

  10. Does bone measurement on the radius indicate skeletal status. Concise communication

    Mazess, R.B.; Peppler, W.W.; Chesney, R.W.; Lange, T.A.; Lindgren, U.; Smith, E. Jr.

    1984-01-01

    Single-photon (I-125) absorptiometry was used to measure bone mineral content (BMC) of the distal third of the radius, and dual-photon absorptiometry (Gd-153) was used to measure total-body bone mineral (TBBM), as well as the BMC of major skeletal regions. Measurements were done in normal females, normal males, osteoporotic females, osteoporotic males, and renal patients. The BMC of the radius predicted TBBM well in normal subjects, but was less satisfactory in the patient groups. The spinal BMC was predicted with even lower accuracy from radius measurement. The error in predicting areal density (bone mass per unit projected skeletal area) of the lumbar and thoracic spine from the radius BMC divided by its width was smaller, but the regressions differed significantly among normals, osteoporotics, and renal patients. There was a preferential spinal osteopenia in the osteoporotic group and in about half of the renal patients. Bone measurements on the radius can indicate overall skeletal status in normal subjects and to a lesser degree in patients, but these radius measurements are inaccurate, even on the average, as an indicator of spinal state

  11. Feasibility of infrared Earth tracking for deep-space optical communications.

    Chen, Yijiang; Hemmati, Hamid; Ortiz, Gerry G

    2012-01-01

    Infrared (IR) Earth thermal tracking is a viable option for optical communications to distant planet and outer-planetary missions. However, blurring due to finite receiver aperture size distorts IR Earth images in the presence of Earth's nonuniform thermal emission and limits its applicability. We demonstrate a deconvolution algorithm that can overcome this limitation and reduce the error from blurring to a negligible level. The algorithm is applied successfully to Earth thermal images taken by the Mars Odyssey spacecraft. With the solution to this critical issue, IR Earth tracking is established as a viable means for distant planet and outer-planetary optical communications. © 2012 Optical Society of America

  12. Entanglement-Assisted Communication System for NASA's Deep-Space Missions

    Kwiat, Paul; Bernstein, Herb; Javadi, Hamid

    2016-01-01

    For this project we have studied various forms of quantum communication, and quantum-enhanced classical communication. In particular, we have performed the first realization of a novel quantum protocol, superdense teleportation. We have also showed that in some cases, the advantages of superdense coding (which enhances classical channel capacity by up to a factor of two) can be realized without the use of entanglement. Finally, we considered some more advanced protocols, with the goal to realize 'superactivation' - two entangled channels have capabilities beyond the sum of the individual channels-and conclude that more study is needed in this area.

  13. Deep Space Network equipment performance, reliability, and operations management information system

    Cooper, T.; Lin, J.; Chatillon, M.

    2002-01-01

    The Deep Space Mission System (DSMS) Operations Program Office and the DeepSpace Network (DSN) facilities utilize the Discrepancy Reporting Management System (DRMS) to collect, process, communicate and manage data discrepancies, equipment resets, physical equipment status, and to maintain an internal Station Log. A collaborative effort development between JPL and the Canberra Deep Space Communication Complex delivered a system to support DSN Operations.

  14. The development of the room temperature LWIR HgCdTe detectors for free space optics communication systems

    Martyniuk, Piotr; Gawron, Waldemar; Mikołajczyk, Janusz

    2017-10-01

    There are many room temperature applications to include free space optics (FSO) communication system combining quantum cascade lasers sources where HgCdTe long-wave (8-12 micrometer) infrared radiation (LWIR) detector reaching ultrafast response time 109 cmHz1/2/W. Since commercially available FSO could operate separately in SWIR, MWIR and LWIR range - the dual band detectors should be implemented into FSO. This paper shows theoretical performance of the dual band back-to-back MWIR and LWIR HgCdTe detector operating at 300 K pointing out the MWIR active layer influence on LWIR operating regime.

  15. ICT and accessibility: an action space perspective on the impact of new information and communication technologies

    Dijst, M.J.

    2004-01-01

    It is frequently asserted in the literature that new Information and Communication Technologies (ICTs) are on the point of a breakthrough into rapid growth. Although we cannot say whether this breakthrough will indeed take place and ― should it do so ― on what scale, in this paper we nevertheless

  16. Telematics and Electronic Communication and Their Effect on Educational Space. [Brief No.] 3.

    Morton, James E.

    A telematics and electronic communication task group examines technology's influence on the educational process as well as the physical classroom, and the needs and concerns these new technologies bring to architects and educators in designing an adaptable classroom. Technology and the classroom are examined in the following areas: the use of…

  17. The 20 and 30 GHz MMIC technology for future space communication antenna system

    Anzic, G.; Connolly, D. J.

    1984-10-01

    The development of fully monolithic gallium arsenide receive and transmit modules is described. These modules are slated for phased array antenna applications in future 30/20 gigahertz communications satellite systems. Performance goals and various approaches to achieve them are discussed. The latest design and performance results of components, submodules and modules are presented.

  18. VIDEO GAMES AS A MEANS OF COMMUNICATION POLICY POST-SOVIET SPACE

    D. A. Iglin

    2016-01-01

    Full Text Available Videogames as a kind of entertainment have a mass nature in the modern world. This aspect involves the opportunity of political advertising and promotion of some kind of political views. This article reviews the political-communicative nature of videogames on the territory of Post-Soviet states.

  19. Differences in Student Information and Communication Technology Literacy Based on Socio-Economic Status, Ethnicity, and Gender: Evidence of a Digital Divide in Florida Schools

    Ritzhaupt, Albert D.; Liu, Feng; Dawson, Kara; Barron, Ann E.

    2013-01-01

    This research examines student information and communication technology (ICT) literacy and its relationships to a student's socio-economic status (SES), gender, and ethnicity of middle school students. We recruited 5,990 students from 13 school districts across the state of Florida. Student participants completed the Student Tool for Technology…

  20. Intergenerational transfer of occupational status in nineteenth century Zeeland, The Netherlands : A test of the influence of industrialisation, mass communication and urbanisation in 117 municipalities

    Zijdeman, Richard L.

    2008-01-01

    Purpose – This paper seeks to study the influence of industrialisation, urbanisation and means of communication on the association between father’s and son’s occupational status in all 117 municipalities in the province of Zeeland, The Netherlands from 1811 to 1890. Design/methodology/approach –

  1. Nano-Particle Scandate Cathode for Space Communications Phase 2, Phase II

    National Aeronautics and Space Administration — We propose an improved cathode based on our novel theory of the role of scandium oxide in enhancing emission in tungsten-impregnated cathodes. Recent results have...

  2. Polarization entangled photon pair source for space-based quantum communication, Phase I

    National Aeronautics and Space Administration — The overall goal of this NASA effort is to develop and deliver efficient, single-pass quantum optical waveguide sources generating high purity hyper-entangled photon...

  3. Inflatable Antennas for CubeSats Communication and Science in Deep Space

    National Aeronautics and Space Administration — The work will be organized as a collaboration between JPL and two external partners: Arizona State University and Meteorological Product Inc. (Mylar manufacturer)....

  4. The JPL optical communications telescope laboratory (OCTL) test bed for the future optical Deep Space Network

    Wilson, K. E.; Page, N.; Wu, J.; Srinivasan, M.

    2003-01-01

    Relative to RF, the lower power-consumption and lower mass of high bandwidth optical telecommunications make this technology extremely attractive for returning data from future NASA/JPL deep space probes.

  5. RFID-Enabled Navigation and Communication Networks for Long-Duration Space Missions, Phase I

    National Aeronautics and Space Administration — Virtual EM Inc. proposes a system that employs semi-passive RFID sensors with carbon nanotube inkjet-printed antenna and solar powered mesh-networked beacons. The...

  6. Cognitive Engine enabled Mission-aware Intelligent Communication System for Space Networking, Phase I

    National Aeronautics and Space Administration — Cognitive radio technology provides spectrum agility to increase the level of cognition and automation. However, spectrum agility alone is not enough to achieve...

  7. On-Chip Quantum Repeater in Diamond for Space-Based Quantum Communication

    National Aeronautics and Space Administration — The focus of my research is on the optical properties of diamond. A diamond is composed of a crystal arrangement of carbon atoms and it is this structure that gives...

  8. Status of CEA reactor studies for a 200 kWe turbo electric space power system

    Carre, F.; Gervaise, F.; Proust, E.; Schwartz, J.P.; Tilliette, Z.; Vrillon, B.

    1986-01-01

    The present European ARIANE space program will expand after 1995 in the development of the large ARIANE 5 launch vehicle. Considering, that the range of power needs (50 to 400 kWe) and operation times required for the space missions planned after the year 2000, are relevant to a nuclear power system, the French Centre National d'Etudes Spatiales (CNES) invited in 1983 the Commissariat a l'Energie Atomique (CEA) to undertake preliminary studies on space power systems. The purpose of the present two year phase (mid 1984-mid 1986) is to identify key technologies for a space generator within the power range of interest and to estimate the development cost of such a project to be examined for commitment in 1986. This work mainly consists in the feasibility and cost assessment of a reference 200 kWe turboelectric space generator, selected for the maturity and availability of the conversion system and for its attractive specific mass compared to thermionics and thermoelectricity, considering the available radiator area afforded by the specific ARIANE 5 geometrical features. The system is basically composed of a fast neutron spectrum lithium cooled reactor, of a Brayton conversion loop and of a heat pipe radiator

  9. Status of the CNES-CEA joint program on space nuclear Brayton systems

    Carre, F.; Proust, E.; Chaudourne, S.; Keirle, P.; Tilliette, Z.; Vrillon, B.

    1989-01-01

    A Cooperative program between the French Centre National d'Etudes Spatiales (CNES) and the Commissariat a l'Engergie Atomique (CEA) was initiated in 1983, to investigate the possible development of 20 to 200 kWe space nuclear power systems to be launched by the next version of the European launcher, Ariane V. After completion in 1986 of preliminary conceptual studies of a reference 200 kWe turboelectric power system, an additional 3 year study phase was decided, with the double objective of assessing the potential advantage of nuclear power systems versus solar photovoltaic or dynamic systems in the 20 kWe power range, and comparing various reactor candidate technologies and systems options for 20 kWe space nuclear power systems, likely to meet the projected energy needs of future European space missions. The results of this study are discussed by the authors

  10. The return of "Gasoline station-park" status into green-open space in DKI Jakarta Province

    Kautsar, L. H. R.; Waryono, T.; Sobirin

    2017-07-01

    The development of gasoline stations in 1970 increased drastically due to the Government support through DKT Jaya Official Note (DKT Jakarta), resulting in a great number of the parks (green open space or RTH - Ruang Terbuka Hijau) converted into a gasoline station. Currently, to meet the RTH target (13.94 % RTH based RTRW [(Rencana Tata Ruang Wilayah) DKT Jakarta 2010], the policy was changed by Decree No.728 year 2009 and Governor Tnstruction No.75 year 2009. Land function of 27 gasoline stations unit must be returned. This study is to determine the appropriateness of gasoline Station-Park conversion into RTH based site and situation approach. The scope of this study was limited only to gasoline stations not converted into RTH. The methodology was the combination of AHP (Analytical Hierarchy Process) and ranking method. Site variables were meant for prone to flooding, the width of land for gasoline station, land status. Situation variables were meant for other public space, availability of other gasoline stations, gasoline stations service, road segments, and the proportions of built space. Analysis study used quantitative descriptive analysis. The results were three of the five gasoline stations were congruence to be converted into a green open space (RTH).

  11. Creating a "third space" in student teaching: Implications for the university supervisor's status as outsider

    Cuenca, Alexander; Schmeichel, Mardi; Butler, Brandon; Dinkelman, Todd; Nichols, Joseph R,

    2011-01-01

    The work of teacher education during student teaching typically takes place in two distinct “spaces”: placement sites and college/university settings. The program featured in this article is structured in ways that clearly mark out those two spaces. Yet this configuration led our university supervisors, whose work primarily took place in the field, to feel like “outsiders.” To redress this concern, a third learning space was incorporated into our student teaching seminar. We suggest that “thi...

  12. Status of the CNES-CEA joint program on space nuclear Brayton systems

    Carre, F.; Proust, E.; Chaudourne, S.; Keirle, P.; Tilliette, Z.; Vrillon, B.

    1989-01-01

    A cooperative program between the French Centre National d'Etudes Spatiales (CNES) and the Commissariat a l'Energie Atomique (CEA) was initiated in 1983, to investigate the possible development of 20 to 200 kWe space nuclear power systems to be launched by the next version of the European launcher, Ariane V. After completion in 1986 of preliminary conceptual studies of a reference 200 kWe turbo-electric power system, an additional 3 year study phase was decided, with the double objective of assessing the potential advantage of nuclear power systems versus solar photovoltaic or dynamic systems in the 20 kWe power range, and comparing various reactor candidate technologies and system options for 20 kWe space nuclear power systems, likely to meet the projected energy needs of future European space missions. A comprehensive program including conceptual design studies, operating transient analyses and technology base assessment, is currently applied to a few reference concepts of 20 kWe nuclear Brayton and thermoelectric systems, in order to establish sound technical and economical bases for selecting the design options and the development strategy of a first space nuclear power system in Europe

  13. Interactive spatial multimedia for communication of art in the physical museum space

    Kortbek, Karen Johanne; Grønbæk, Kaj

    2008-01-01

    of the artworks we apply three spatial multimedia techniques where the only interaction device needed is the human body. The three techniques are: 1) spatially bounded audio; 2) floor-based multimedia; 3) multimedia interior. The paper describes the application of these techniques for communication of information...... without disturbing the art works. This has usually been limited to individual audio guides. In our case we strive to achieve holistic and social experiences with seamless transitions between art experience and communication related to the artworks. To reach a holistic experience with minimal disturbance...... in a Mariko Mori exhibition. The multimedia installations and their implementation are described. It is argued that the utilization of the spatial multimedia techniques support holistic and social art experience. The multimedia installations were in function for a three and a half month exhibition period...

  14. High-Rate Communications Outage Recorder Operations for Optimal Payload and Science Telemetry Management Onboard the International Space Station

    Shell, Michael T.; McElyea, Richard M. (Technical Monitor)

    2002-01-01

    All International Space Station (ISS) Ku-band telemetry transmits through the High-Rate Communications Outage Recorder (HCOR). The HCOR provides the recording and playback capability for all payload, science, and International Partner data streams transmitting through NASA's Ku-band antenna system. The HCOR is a solid-state memory recorder that provides recording capability to record all eight ISS high-rate data during ISS Loss-of-Signal periods. NASA payloads in the Destiny module are prime users of the HCOR; however, NASDA and ESA will also utilize the HCOR for data capture and playback of their high data rate links from the Kibo and Columbus modules. Marshall Space Flight Center's Payload Operations Integration Center manages the HCOR for nominal functions, including system configurations and playback operations. The purpose of this paper is to present the nominal operations plan for the HCOR and the plans for handling contingency operations affecting payload operations. In addition, the paper will address HCOR operation limitations and the expected effects on payload operations. The HCOR is manifested for ISS delivery on flight 9A with the HCOR backup manifested on flight 11A. The HCOR replaces the Medium-Rate Communications Outage Recorder (MCOR), which has supported payloads since flight 5A.1.

  15. Detecting binary non-return-to-zero data in free-space optical communication systems using FPGAs

    Bui, Vy; Tran, Lan; El-Araby, Esam; Namazi, Nader M.

    2014-06-01

    High bandwidth, fast deployment with relatively low cost implementation are some of the important advantages of free space optical (FSO) communications. However, the atmospheric turbulence has a substantial impact on the quality of a laser beam propagating through the atmosphere. A new method was presented in [1] and [2] to perform bit synchronization and detection of binary Non-Return-to-Zero (NRZ) data from a free-space optical (FSO) communication link. It was shown that, when the data is binary NRZ with no modulation, the Haar wavelet transformation can effectively reduce the scintillation noise. In this paper, we leverage and modify the work presented in [1] in order to provide a real-time streaming hardware prototype. The applicability of these concepts will be demonstrated through providing the hardware prototype using one of the state-of-the-art reconfigurable hardware, namely Field Programmable Gate Arrays, and highly productive high-level design tools such as System Generator for DSP from Xilinx.

  16. Demonstration of free-space optical communication for long-range data links between balloons on Project Loon

    Moision, Bruce; Erkmen, Baris; Keyes, Edward; Belt, Todd; Bowen, Oliver; Brinkley, Devin; Csonka, Paul; Eglington, Michael; Kazmierski, Andrei; Kim, Nam-hyong; Moody, John; Tu, Thanh; Vermeer, William

    2017-02-01

    Internet connectivity is limited and in some cases non-existent for a significant part of the world's population. Project Loon aims to address this with a network of high-altitude balloons traveling in the stratosphere, at an altitude of approximately 20 km. The balloons navigate by using the stratified wind layers at different altitudes, adjusting the balloon's altitude to catch winds in a desired direction. Data transfer is achieved by 1) uplinking a signal from an Internet-connected ground station to a balloon terminal, 2) crosslinking the signal through the balloon network to reach the geographic area of the users, and 3) downlinking the signal directly to the end-users' phones or other LTE-enabled devices. We describe Loon's progress on utilizing free-space optical communications (FSOC) for the inter-balloon crosslinks. FSOC, offering high data rates and long communication ranges, is well-suited for communication between high-altitude platforms. A stratospheric link is sufficiently high to be above weather events (clouds, fog, rain, etc.), and the impact of atmospheric turbulence is significantly weaker than at ground level. In addition, being in the stratosphere as opposed to space helps avoid the typical challenges faced by space-based systems, namely operation in a vacuum environment with significant radiation. Finally, the angular pointing disturbances introduced by a floating balloon-based platform are notably less than any propelled platform, which simplifies the disturbance rejection requirements on the FSOC system. We summarize results from Project Loon's early-phase experimental inter-balloon links at 20 km altitude, demonstrating full duplex 130 Mbps throughput at distances in excess of 100 km over the course of several-day flights. The terminals utilize a monostatic design, with dual wavelengths for communication and a dedicated wide-angle beacon for pointing, acquisition, and tracking. We summarize the constraints on the terminal design, and the

  17. Quantifying loss of acoustic communication space for right whales in and around a U.S. National Marine Sanctuary.

    Hatch, Leila T; Clark, Christopher W; Van Parijs, Sofie M; Frankel, Adam S; Ponirakis, Dimitri W

    2012-12-01

    The effects of chronic exposure to increasing levels of human-induced underwater noise on marine animal populations reliant on sound for communication are poorly understood. We sought to further develop methods of quantifying the effects of communication masking associated with human-induced sound on contact-calling North Atlantic right whales (Eubalaena glacialis) in an ecologically relevant area (~10,000 km(2) ) and time period (peak feeding time). We used an array of temporary, bottom-mounted, autonomous acoustic recorders in the Stellwagen Bank National Marine Sanctuary to monitor ambient noise levels, measure levels of sound associated with vessels, and detect and locate calling whales. We related wind speed, as recorded by regional oceanographic buoys, to ambient noise levels. We used vessel-tracking data from the Automatic Identification System to quantify acoustic signatures of large commercial vessels. On the basis of these integrated sound fields, median signal excess (the difference between the signal-to-noise ratio and the assumed recognition differential) for contact-calling right whales was negative (-1 dB) under current ambient noise levels and was further reduced (-2 dB) by the addition of noise from ships. Compared with potential communication space available under historically lower noise conditions, calling right whales may have lost, on average, 63-67% of their communication space. One or more of the 89 calling whales in the study area was exposed to noise levels ≥120 dB re 1 μPa by ships for 20% of the month, and a maximum of 11 whales were exposed to noise at or above this level during a single 10-min period. These results highlight the limitations of exposure-threshold (i.e., dose-response) metrics for assessing chronic anthropogenic noise effects on communication opportunities. Our methods can be used to integrate chronic and wide-ranging noise effects in emerging ocean-planning forums that seek to improve management of cumulative effects

  18. What Makes You Tick? An Empirical Study of Space Science Related Social Media Communications Using Machine Learning

    Hwong, Y. L.; Oliver, C.; Van Kranendonk, M. J.

    2016-12-01

    The rise of social media has transformed the way the public engages with scientists and science organisations. `Retweet', `Like', `Share' and `Comment' are a few ways users engage with messages on Twitter and Facebook, two of the most popular social media platforms. Despite the availability of big data from these digital footprints, research into social media science communication is scant. This paper presents the results of an empirical study into the processes and outcomes of space science related social media communications using machine learning. The study is divided into two main parts. The first part is dedicated to the use of supervised learning methods to investigate the features of highly engaging messages., e.g. highly retweeted tweets and shared Facebook posts. It is hypothesised that these messages contain certain psycholinguistic features that are unique to the field of space science. We built a predictive model to forecast the engagement levels of social media posts. By using four feature sets (n-grams, psycholinguistics, grammar and social media), we were able to achieve prediction accuracies in the vicinity of 90% using three supervised learning algorithms (Naive Bayes, linear classifier and decision tree). We conducted the same experiments on social media messages from three other fields (politics, business and non-profit) and discovered several features that are exclusive to space science communications: anger, authenticity, hashtags, visual descriptions and a tentative tone. The second part of the study focuses on the extraction of topics from a corpus of texts using topic modelling. This part of the study is exploratory in nature and uses an unsupervised method called Latent Dirichlet Allocation (LDA) to uncover previously unknown topics within a large body of documents. Preliminary results indicate a strong potential of topic model algorithms to automatically uncover themes hidden within social media chatters on space related issues, with

  19. NASA advanced space photovoltaic technology-status, potential and future mission applications

    Flood, Dennis J.; Piszczor, Michael, Jr.; Stella, Paul M.; Bennett, Gary L.

    1989-01-01

    The NASA program in space photovoltaic research and development encompasses a wide range of emerging options for future space power systems, and includes both cell and array technology development. The long range goals are to develop technology capable of achieving 300 W/kg for planar arrays, and 300 W/sq m for concentrator arrays. InP and GaAs planar and concentrator cell technologies are under investigation for their potential high efficiency and good radiation resistance. The Advanced Photovoltaic Solar Array (APSA) program is a near term effort aimed at demonstrating 130 W/kg beginning of life specific power using thin (62 micrometer) silicon cells. It is intended to be technology transparent to future high efficiency cells and provides the baseline for development of the 300 W/kg array.

  20. Status of CEA design and simulation studies of 200 KWe turboelectric space power system

    Carre, F.; Proust, E.; Gervaise, F.; Schwartz, J.P.; Tilliette, Z.; Vrillon, B.

    1987-01-01

    This paper presents the updated design features of the reference 200 kWe turboelectric space generator studied in France, and comments some of the alternative options to be analyzed in the near future, concerning the reactor and the conversion system in particular. Also presented the major conclusions of the simulation studies, that have been performed to analyze the overall behavior of the reference generator, during the start up and the accidental transients

  1. Beyond “Political” Communicative Spaces : Talking Politics on the Wife Swap Discussion Forum

    Graham, T.S.

    2012-01-01

    Net-based public sphere researchers have examined online deliberation in numerous ways. However, most studies have focused exclusively on political discussion forums. This article moves beyond such spaces by analyzing political talk from an online forum dedicated to reality television. The purpose

  2. Volume transmission in health and disease: communication via the brain extracellular space

    Syková, Eva

    2003-01-01

    Roč. 85, č. 2 (2003), s. 2 ISSN 0022-3042. [Meeting of the European Society for Neurochemistry /14./. Varšava, 01.06.2003-04.06.2003] Institutional research plan: CEZ:AV0Z5039906 Keywords : volume transmission * extracellular space Subject RIV: FH - Neurology Impact factor: 4.825, year: 2003

  3. Indoor Off-Body Wireless Communication: Static Beamforming versus Space-Time Coding

    Patrick Van Torre

    2012-01-01

    Full Text Available The performance of beamforming versus space-time coding using a body-worn textile antenna array is experimentally evaluated for an indoor environment, where a walking rescue worker transmits data in the 2.45 GHz ISM band, relying on a vertical textile four-antenna array integrated into his garment. The two transmission scenarios considered are static beamforming at low-elevation angles and space-time code based transmit diversity. Signals are received by a base station equipped with a horizontal array of four dipole antennas providing spatial receive diversity through maximum-ratio combining. Signal-to-noise ratios, bit error rate characteristics, and signal correlation properties are assessed for both off-body transmission scenarios. Without receiver diversity, the performance of space-time coding is generally better. In case of fourth-order receiver diversity, beamforming is superior in line-of-sight conditions. For non-line-of-sight propagation, the space-time codes perform better as soon as bit error rates are low enough for a reliable data link.

  4. An Optimizing Space Data-Communications Scheduling Method and Algorithm with Interference Mitigation, Generalized for a Broad Class of Optimization Problems

    Rash, James

    2014-01-01

    NASA's space data-communications infrastructure-the Space Network and the Ground Network-provide scheduled (as well as some limited types of unscheduled) data-communications services to user spacecraft. The Space Network operates several orbiting geostationary platforms (the Tracking and Data Relay Satellite System (TDRSS)), each with its own servicedelivery antennas onboard. The Ground Network operates service-delivery antennas at ground stations located around the world. Together, these networks enable data transfer between user spacecraft and their mission control centers on Earth. Scheduling data-communications events for spacecraft that use the NASA communications infrastructure-the relay satellites and the ground stations-can be accomplished today with software having an operational heritage dating from the 1980s or earlier. An implementation of the scheduling methods and algorithms disclosed and formally specified herein will produce globally optimized schedules with not only optimized service delivery by the space data-communications infrastructure but also optimized satisfaction of all user requirements and prescribed constraints, including radio frequency interference (RFI) constraints. Evolutionary algorithms, a class of probabilistic strategies for searching large solution spaces, is the essential technology invoked and exploited in this disclosure. Also disclosed are secondary methods and algorithms for optimizing the execution efficiency of the schedule-generation algorithms themselves. The scheduling methods and algorithms as presented are adaptable to accommodate the complexity of scheduling the civilian and/or military data-communications infrastructure within the expected range of future users and space- or ground-based service-delivery assets. Finally, the problem itself, and the methods and algorithms, are generalized and specified formally. The generalized methods and algorithms are applicable to a very broad class of combinatorial

  5. Preliminary Experiments for the Assessment of VW-Band Links for Space-Earth Communications

    Nessel, James A.; Acosta, Roberto J.; Miranda, Felix A.

    2013-01-01

    Since September 2012, NASA Glenn Research Center has deployed a microwave profiling radiometer at White Sands, NM, to estimate atmospheric propagation effects on communications links in the V and W bands (71-86GHz). Estimates of attenuation statistics in the millimeter wave due to gaseous and cloud components of the atmosphere show good agreement with current ITU-R models, but fail to predict link performance in the presence of moderate to heavy rain rates, due to the inherent limitations of passive radiometry. Herein, we discuss the preliminary results of these measurements and describe a design for a terrestrial link experiment to validaterefine existing rain attenuation models in the VW-bands.

  6. Fibercore AstroGain fiber: multichannel erbium doped fibers for optical space communications

    Hill, Mark; Gray, Rebecca; Hankey, Judith; Gillooly, Andy

    2014-03-01

    Fibercore have developed AstroGainTM fiber optimized for multichannel amplifiers used in optical satellite communications and control. The fiber has been designed to take full advantage of the photo-annealing effect that results from pumping in the 980nm region. The proprietary trivalent structure of the core matrix allows optimum recovery following radiation damage to the fiber, whilst also providing a market leading Erbium Doped Fiber Amplifier (EDFA) efficiency. Direct measurements have been taken of amplifier efficiency in a multichannel assembly, which show an effective photo-annealing recovery of up to 100% of the radiation induced attenuation through excitation of point defects.

  7. Activity Theory, Hybrid Experience Space Design and Cultural Heritage Communication at Lindholm Høje

    Christensen, Mogens Fiil; Veirum, Niels Einar

    This paper deals with the questions of how to address the communication of cultural heritage in the post-industrialized societies of the globalized economy. The last two or three decades have radically changed the relationship between the individual and the national institutions, encompassing...... the institutions of cultural heritage, museums and foundations. From an expert founded representation of facts, based on a rational and linear understanding of knowledge being presented to a mass customer, to a situation where an individualized customer, accustomed to a range of choices and the ability to interact...

  8. Shuttle Ku-band bent-pipe implementation considerations. [for Space Shuttle digital communication systems

    Batson, B. H.; Seyl, J. W.; Huth, G. K.

    1977-01-01

    This paper describes an approach for relay of data-modulated subcarriers from Shuttle payloads through the Shuttle Ku-band communications subsystem (and subsequently through a tracking and data relay satellite system to a ground terminal). The novelty is that a channel originally provided for baseband digital data is shown to be suitable for this purpose; the resulting transmission scheme is referred to as a narrowband bent-pipe scheme. Test results demonstrating the validity of the narrowband bent-pipe mode are presented, and limitations on system performance are described.

  9. Status update of a free-piston Stirling convertor for radioisotope space power systems

    White, Maurice; Qiu Songgang; Augenblick, Jack; Peterson, Allen; Faultersack, Frank

    2001-01-01

    Free-piston Stirling engines offer a relatively mature technology that is well-suited for advanced, high-efficiency radioisotope space power systems. This paper updates results from a combination of DOE and NASA contracts with Stirling Technology Company (STC). These contracts have demonstrated STC's Stirling convertor technology in a configuration and power level representative of a space power system. Based on demonstrated performance, long-life maintenance-free technology heritage, and success with aggressively imposed vibration testing. DOE has awarded system integration contracts to Boeing, Lockheed Martin and Teledyne Energy Systems. The objectives of these competitive Phase I contracts are to develop complete spacecraft power system conceptual designs based on the STC Stirling convertor, and to plan subsequent phases for two launches. Performance results for the DOE 55-W(e) Technology Demonstration Convertors (TDC's) have met original projections. Although the TDC's were intended only for technology demonstration, they have achieved very aggressive efficiency goals, demonstrated convertor-induced vibration levels below the Jet Propulsion Laboratory (JPL) specifications, passed a simulated launch load vibration test at 0.2 g2/Hz (12.3 g rms), and met EMI/EMC goals for most contemplated missions. No consideration for EMI reduction was included in the TDC design. Minor changes are underway to reduce EMI levels, with a goal of meeting specifications for missions such as Solar Probe with highly sensitive instrumentation. The long-term objective for DOE is to develop a power system with a system efficiency exceeding 20% that can function with a high degree of reliability for 10 years and longer on deep space missions

  10. Status update of a free-piston Stirling convertor for radioisotope space power systems

    White, Maurice; Qiu, Songgang; Augenblick, Jack; Peterson, Allen; Faultersack, Frank

    2001-02-01

    Free-piston Stirling engines offer a relatively mature technology that is well-suited for advanced, high-efficiency radioisotope space power systems. This paper updates results from a combination of DOE and NASA contracts with Stirling Technology Company (STC). These contracts have demonstrated STC's Stirling convertor technology in a configuration and power level representative of a space power system. Based on demonstrated performance, long-life maintenance-free technology heritage, and success with aggressively imposed vibration testing. DOE has awarded system integration contracts to Boeing, Lockheed Martin and Teledyne Energy Systems. The objectives of these competitive Phase I contracts are to develop complete spacecraft power system conceptual designs based on the STC Stirling convertor, and to plan subsequent phases for two launches. Performance results for the DOE 55-W(e) Technology Demonstration Convertors (TDC's) have met original projections. Although the TDC's were intended only for technology demonstration, they have achieved very aggressive efficiency goals, demonstrated convertor-induced vibration levels below the Jet Propulsion Laboratory (JPL) specifications, passed a simulated launch load vibration test at 0.2 g2/Hz (12.3 g rms), and met EMI/EMC goals for most contemplated missions. No consideration for EMI reduction was included in the TDC design. Minor changes are underway to reduce EMI levels, with a goal of meeting specifications for missions such as Solar Probe with highly sensitive instrumentation. The long-term objective for DOE is to develop a power system with a system efficiency exceeding 20% that can function with a high degree of reliability for 10 years and longer on deep space missions. .

  11. Fiber-Coupled Wide Field of View Optical Receiver for High Speed Space Communication

    Suddath, Shannon N.

    Research groups at NASA Glenn Research Center are interested in improving data rates on the International Space Station (ISS) using a free-space optical (FSO) link. However, known flexure of the ISS structure is expected to cause misalignment of the FSO link. Passive-control designs for mitigating misalignment are under investigation, including using a fiber-bundle for improved field of view. The designs must overcome the obstacle of coupling directly to fiber, rather than a photodetector, as NASA will maintain the use of small form-factor pluggable optical transceivers (SFPs) in the ISS network. In this thesis, a bundle-based receiver capable of coupling directly to fiber is designed, simulated, and tested in lab. Two 3-lens systems were evaluated for power performance in the lab, one with a 20 mm focal length aspheric lens and the other with a 50 mm focal length aspheric lens. The maximum output power achieved was 8 muW.

  12. A 12 GHz wavelength spacing multi-wavelength laser source for wireless communication systems

    Peng, P. C.; Shiu, R. K.; Bitew, M. A.; Chang, T. L.; Lai, C. H.; Junior, J. I.

    2017-08-01

    This paper presents a multi-wavelength laser source with 12 GHz wavelength spacing based on a single distributed feedback laser. A light wave generated from the distributed feedback laser is fed into a frequency shifter loop consisting of 50:50 coupler, dual-parallel Mach-Zehnder modulator, optical amplifier, optical filter, and polarization controller. The frequency of the input wavelength is shifted and then re-injected into the frequency shifter loop. By re-injecting the shifted wavelengths multiple times, we have generated 84 optical carriers with 12 GHz wavelength spacing and stable output power. For each channel, two wavelengths are modulated by a wireless data using the phase modulator and transmitted through a 25 km single mode fiber. In contrast to previously developed schemes, the proposed laser source does not incur DC bias drift problem. Moreover, it is a good candidate for radio-over-fiber systems to support multiple users using a single distributed feedback laser.

  13. Crew-MC communication and characteristics of crewmembers' sleep under conditions of simulated prolonged space flight

    Shved, Dmitry; Gushin, Vadim; Yusupova, Anna; Ehmann, Bea; Balazs, Laszlo; Zavalko, Irina

    Characteristics of crew-MC communication and psychophysiological state of the crewmembers were studied in simulation experiment with 520-day isolation. We used method of computerized quantitative content analysis to investigate psychologically relevant characteristics of the crew’s messages content. Content analysis is a systematic, reproducible method of reducing of a text array to a limited number of categories by means of preset scientifically substantiated rules of coding (Berelson, 1971, Krippendorff, 2004). All statements in the crew’s messages to MC were coded with certain psychologically relevant content analysis categories (e.g. ‘Needs’, ‘Negativism’, ‘Time’). We attributed to the ‘Needs’ category statements (semantic units), containing the words, related to subject’s needs and their satisfaction, e.g. ‘‘necessary, need, wish, want, demand’’. To the ‘Negativism’ category we refer critical statements, containing such words as ‘‘mistakes, faults, deficit, shortage’’. The ‘Time’ category embodies statements related to time perception, e.g. “hour, day, always, never, constantly”. Sleep study was conducted with use of EEG and actigraphy techniques to assess characteristics of the crewmembers’ night sleep, reflecting the crew’s adaptation to the experimental conditions. The overall amount of communication (quantity of messages and their length) positively correlated with sleep effectiveness (time of sleep related to time in bed) and with delta sleep latency. Occurrences of semantic units in categories ‘Time’ and ‘Negativism’ negatively correlated with sleep latency, and positively - with delta sleep latency and sleep effectiveness. Frequency of time-related semantic units’ utilization in the crew’s messages was significantly increasing during or before the key events of the experiment (beginning of high autonomy, planetary landing simulation, etc.). It is known that subjective importance of time

  14. International Space Station Environmental Control and Life Support System Status: 2008 - 2009

    Williams, David E.; Gentry, Gregory J.; Gentry, Gregory J.

    2009-01-01

    The International Space Station (ISS) Environmental Control and Life Support (ECLS) system includes regenerative and non-regenerative technologies that provide the basic life support functions to support the crew, while maintaining a safe and habitable shirtsleeve environment. This paper provides a summary of the U.S. ECLS system activities over the past year, covering the period of time between March 2008 and February 2009. The ISS continued permanent crew operations, with the continuation of Phase 3 of the ISS Assembly Sequence. Work continues on the last of the Phase 3 pressurized elements and the continued manufacturing and testing of the regenerative ECLS equipment.

  15. International Space Station Environmental Control and Life Support System Status: 2010 - 2011

    Williams, David E.; Gentry, Gregory J.

    2010-01-01

    The International Space Station (ISS) Environmental Control and Life Support (ECLS) system includes regenerative and non-regenerative technologies that provide the basic life support functions to support the crew, while maintaining a safe and habitable shirtsleeve environment. This paper provides a summary of the U.S. ECLS system activities over the past year, covering the period of time between March 2010 and February 2011 and the continued permanent presence of six crew members on ISS. Work continues on the last of the Phase 3 pressurized elements, commercial cargo resupply vehicles, and extension of the ISS service life from 2015 to 2020 or beyond.

  16. International Space Station Environmental Control and Life Support System Status for the Prior Year: 2011 - 2012

    Williams, David E.; Dake, Jason R.; Gentry, Gregory J

    2013-01-01

    The International Space Station (ISS) Environmental Control and Life Support (ECLS) system includes regenerative and non-regenerative technologies that provide the basic life support functions to support the crew, while maintaining a safe and habitable shirtsleeve environment. This paper provides a summary of the U.S. ECLS system activities over the prior year, covering the period of time between March 2011 and February 2012. The ISS continued permanent crew operations including the continuation of six crew members being on ISS. Work continues on the last of the Phase 3 pressurized elements, the commercial cargo resupply vehicles, and work to try and extend ISS service life from 2015 to at least 2028.

  17. International Space Station Environmental Control and Life Support System Status: 2009 - 2010

    Williams, David E.; Dake, Jason R.; Gentry, Gregory J.

    2010-01-01

    The International Space Station (ISS) Environmental Control and Life Support (ECLS) system includes regenerative and non -regenerative technologies that provide the basic life support functions to support the crew, while maintaining a safe and habitable shirtsleeve environment. This paper provides a summary of the U.S. ECLS system activities over the past year, covering the period of time between March 2009 and February 2010. The ISS continued permanent crew operations, with the start of Phase 3 of the ISS Assembly Sequence and an increase of the ISS crew size from three to six. Work continues on the last of the Phase 3 pressurized elements.

  18. International Space Station Environmental Control and Life Support System Previous Year Status for 2013 - 2014

    Williams, David E.; Gentry, Gregory J.

    2015-01-01

    The International Space Station (ISS) Environmental Control and Life Support (ECLS) system includes regenerative and non-regenerative technologies that provide the basic life support functions to support the crew, while maintaining a safe and habitable shirtsleeve environment. This paper provides a summary of the U.S. ECLS system activities over the past year and the impacts of the international partners' activities on them, covering the period of time between March 2013 and February 2014. The ISS continued permanent crew operations including the continuation of six crew members being on ISS. Work continues on the commercial crew vehicles, and work to try and extend ISS service life.

  19. International Space Station Environmental Control and Life Support System Status: 2014-2015

    Williams, David E.; Gentry, Gregory J.

    2015-01-01

    The International Space Station (ISS) Environmental Control and Life Support (ECLS) system includes regenerative and non-regenerative technologies that provide the basic life support functions to support the crew, while maintaining a safe and habitable shirtsleeve environment. This paper provides a summary of the U.S. ECLS system activities over the past year and the impacts of the international partners' activities on them, covering the period of time between March 2014 and February 2015. The ISS continued permanent crew operations including the continuation of six crew members being on ISS. Work continues on the commercial crew vehicles, and work to try and extend ISS service life.

  20. Use of the 37-38 GHz and 40-40.5 GHz Ka-bands for Deep Space Communications

    Morabito, David; Hastrup, Rolf

    2004-01-01

    This paper covers a wide variety of issues associated with the implementation and use of these frequency bands for deep space communications. Performance issues, such as ground station pointing stability, ground antenna gain, antenna pattern, and propagation effects such as due to atmospheric, charged-particle and space loss at 37 GHz, will be addressed in comparison to the 32 GHz Ka-band deep space allocation. Issues with the use of and competition for this spectrum also will be covered. The state of the hardware developed (or proposed) for operating in this frequency band will be covered from the standpoint of the prospects for achieving higher data rates that could be accommodated in the available bandwidth. Hardware areas to be explored include modulators, digital-to-analog converters, filters, power amplifiers, receivers, and antennas. The potential users of the frequency band will be explored as well as their anticipated methods to achieve the potential high data rates and the implications of the competition for bandwidth.

  1. The association between parent-reported provider communication quality and child obesity status: Variation by parent obesity and child race/ethnicity.

    Wong, Michelle S; Showell, Nakiya N; Bleich, Sara N; Gudzune, Kimberly A; Chan, Kitty S

    2017-08-01

    To examine the association between healthcare provider communication quality and child obesity status, and the role of parent obesity and child race/ethnicity regarding this association. We conducted a cross-sectional secondary data analysis with the 2011-2013 Medical Expenditures Panel Survey of parents with children ages 6-12 (n=5390). We used multivariable logistic regression to examine the association of parent-reported healthcare provider communication quality (explaining well, listening carefully, showing respect, and spending enough time) with child obesity status, and effect modification by parent obesity and child race/ethnicity. Parents of obese children were more likely to report that their child's healthcare provider listened carefully (OR=1.41, p=0.002) and spent enough time (OR=1.33, p=0.022) than parents of non-obese children. Non-obese parents of obese children experienced better communication in the domains of listening carefully (pobese non-Hispanic Asian children and non-Hispanic Black children were more likely to report that providers explained things well (p=0.043) and listened carefully (p=0.012), respectively. Parents of obese children experienced better communication if parents were non-obese or children were non-Hispanic Black or Asian. Healthcare providers should ensure effective communication with obese parents of obese children. Copyright © 2017 Elsevier B.V. All rights reserved.

  2. Status of CEA reactor studies for a 200 kWe turboelectric Space Power System

    Carre, F.; Gervaise, F.; Proust, E.; Schwartz, J.P.; Tilliette, Z.; Vrillon, B.

    1986-01-01

    A reference design for a 200 kWe Space Nuclear Power System has been developed by the CNES and CEA Agencies of the French Government in order to assess within a first study phase running from mid 1984 to mid 1986, the key feasibility issues and the development cost of a Space Power System compatible with the version of the European launcher (ARIANE V), that will be available after 1995, and with adequate power range and lifetime performances for the missions considered at that time. The heat from a fast spectrum lithium cooled reactor is converted by a turboelectric system, selected for its technological readiness and for its advantage over thermionics and thermoelectricity, of minimizing the total mass of 100 to 300 kWe power systems, considering the available radiator area afforded by the specific ARIANE V geometrical features. A heat pipe radiator is preferred to an equivalent gas cooled system, for the increased reliability brought by the large number of independent cooling elements. The successive topics addressed in the paper, include a description of the system main components and steady state operating conditions, and the present views about the start up procedure and the reactor control

  3. Fast and reliable control of steering mirrors with application to free-space communication

    Ibrir, Salim; Su, Chun-Yi; Ooi, Boon S.; Alouini, Mohamed-Slim

    2018-01-01

    After modeling a laser beam pointing system actuated by a piezo-electric fast steering mirror (FSM), an observer-based linear feedback controller is developed to correct the position of the laser spot communicated by the position sensing detector (PSD). The modeling and the control actions have been considered with and without the hysteresis effect induced by the piezoelectric actuators of the FSM. The design of the feedback is given through the solution of parametric matrix inequalities. It was found that the integral feedback design is very efficient in handling input and system uncertainty. The linearity of the observer-based feedback has facilitated both the real-time implementation of the control strategy and the proof of stability using dynamic-output feedbacks.

  4. Fast and reliable control of steering mirrors with application to free-space communication

    Ibrir, Salim

    2018-03-15

    After modeling a laser beam pointing system actuated by a piezo-electric fast steering mirror (FSM), an observer-based linear feedback controller is developed to correct the position of the laser spot communicated by the position sensing detector (PSD). The modeling and the control actions have been considered with and without the hysteresis effect induced by the piezoelectric actuators of the FSM. The design of the feedback is given through the solution of parametric matrix inequalities. It was found that the integral feedback design is very efficient in handling input and system uncertainty. The linearity of the observer-based feedback has facilitated both the real-time implementation of the control strategy and the proof of stability using dynamic-output feedbacks.

  5. LDPC-coded orbital angular momentum (OAM) modulation for free-space optical communication.

    Djordjevic, Ivan B; Arabaci, Murat

    2010-11-22

    An orbital angular momentum (OAM) based LDPC-coded modulation scheme suitable for use in FSO communication is proposed. We demonstrate that the proposed scheme can operate under strong atmospheric turbulence regime and enable 100 Gb/s optical transmission while employing 10 Gb/s components. Both binary and nonbinary LDPC-coded OAM modulations are studied. In addition to providing better BER performance, the nonbinary LDPC-coded modulation reduces overall decoder complexity and latency. The nonbinary LDPC-coded OAM modulation provides a net coding gain of 9.3 dB at the BER of 10(-8). The maximum-ratio combining scheme outperforms the corresponding equal-gain combining scheme by almost 2.5 dB.

  6. Preliminary Experiments for the Assessment of V/W-band Links for Space-Earth Communications

    Nessel, James A.; Acosta, Roberto J.; Miranda, Felix A.

    2013-01-01

    Since September 2012, NASA Glenn Research Center has deployed a microwave profiling radiometer at White Sands, NM, to estimate atmospheric propagation effects on communications links in the V and W bands (71-86GHz). Estimates of attenuation statistics in the millimeter wave due to gaseous and cloud components of the atmosphere show good agreement with current ITU-R models, but fail to predict link performance in the presence of moderate to heavy rain rates, due to the inherent limitations of passive radiometry. Herein, we discuss the preliminary results of these measurements and describe a design for a terrestrial link experiment to validate/refine existing rain attenuation models in the V/Wbands.

  7. Status and Perspective of the Hydraulic Solver development for SPACE code

    Lee, S. Y.; Oh, M. T.; Park, J. C.; Ahn, S. J.; Park, C. E.; Lee, E. J.; Na, Y. W.

    2008-01-01

    KOPEC has been developing a hydraulic solver for SPACE code. The governing equations for the solver can be obtained through several steps of modeling and approximations from the basic material transport principles. Once the governing equations are fixed, a proper discretization procedure should be followed to get the difference equations that can be solved by well established matrix solvers. Of course, the mesh generation and handling procedures are necessary for the discretization process. At present, the preliminary test version has been constructed and being tested. The selection of the compiler language was debated openly. C++ was chosen as a basis compiler language. But other language such as FORTRAN can be used as it is necessary. The steps mentioned above are explained in the following sections. Test results are presented by other companion papers in this meeting. Future activities will be described in the conclusion section

  8. International Space Station Environmental Control and Life Support System Status: 2011-2012

    Williams, David E.; Dake, Jason R.; Gentry, Gregory J.

    2011-01-01

    The International Space Station (ISS) Environmental Control and Life Support (ECLS) system includes regenerative and non-regenerative technologies that provide the basic life support functions to support the crew, while maintaining a safe and habitable shirtsleeve environment. This paper provides a summary of the U.S. ECLS system activities over the past year and the impacts of the international partners activities on them, covering the period of time between March 2011 and February 2012. The ISS continued permanent crew operations including the continuation of six crew members being on ISS. Work continues on the commercial cargo resupply vehicles, and work to try and extend ISS service life from 2015 to no later than 2028. 1

  9. Communication: Relativistic Fock-space coupled cluster study of small building blocks of larger uranium complexes

    Tecmer, Paweł; Visscher, Lucas; Severo Pereira Gomes, André; Knecht, Stefan

    2014-01-01

    We present a study of the electronic structure of the [UO 2 ] + , [UO 2 ] 2 + , [UO 2 ] 3 + , NUO, [NUO] + , [NUO] 2 + , [NUN] − , NUN, and [NUN] + molecules with the intermediate Hamiltonian Fock-space coupled cluster method. The accuracy of mean-field approaches based on the eXact-2-Component Hamiltonian to incorporate spin–orbit coupling and Gaunt interactions are compared to results obtained with the Dirac–Coulomb Hamiltonian. Furthermore, we assess the reliability of calculations employing approximate density functionals in describing electronic spectra and quantities useful in rationalizing Uranium (VI) species reactivity (hardness, electronegativity, and electrophilicity)

  10. Communication: Relativistic Fock-space coupled cluster study of small building blocks of larger uranium complexes

    Tecmer, Paweł; Severo Pereira Gomes, André; Knecht, Stefan; Visscher, Lucas

    2014-07-01

    We present a study of the electronic structure of the [UO2]+, [UO2]2 +, [UO2]3 +, NUO, [NUO]+, [NUO]2 +, [NUN]-, NUN, and [NUN]+ molecules with the intermediate Hamiltonian Fock-space coupled cluster method. The accuracy of mean-field approaches based on the eXact-2-Component Hamiltonian to incorporate spin-orbit coupling and Gaunt interactions are compared to results obtained with the Dirac-Coulomb Hamiltonian. Furthermore, we assess the reliability of calculations employing approximate density functionals in describing electronic spectra and quantities useful in rationalizing Uranium (VI) species reactivity (hardness, electronegativity, and electrophilicity).

  11. Modeling of Fog and Smoke Attenuation in Free Space Optical Communications Link Under Controlled Laboratory Conditions

    Ijaz, M.; Ghassemlooy, Z.; Pešek, J.; Fišer, Ondřej; Le Minh, H.; Bentley, E.

    2013-01-01

    Roč. 31, č. 11 (2013), s. 1720-1726 ISSN 0733-8724 R&D Projects: GA ČR(CZ) GAP102/11/1376 Institutional support: RVO:68378289 Keywords : Fog attenuation * free space optics * smoke attenuation * visibility Subject RIV: DG - Athmosphere Sciences, Meteorology Impact factor: 2.862, year: 2013 http://ieeexplore.ieee.org/xpl/login.jsp?tp=&arnumber=6497447&url=http%3A%2F%2Fieeexplore.ieee.org%2Fxpls%2Fabs_all.jsp%3Farnumber%3D6497447

  12. Performance and Characterization of a Modular Superconducting Nanowire Single Photon Detector System for Space-to-Earth Optical Communications Links

    Vyhnalek, Brian E.; Tedder, Sarah A.; Nappier, Jennifer M.

    2018-01-01

    Space-to-ground photon-counting optical communication links supporting high data rates over large distances require enhanced ground receiver sensitivity in order to reduce the mass and power burden on the spacecraft transmitter. Superconducting nanowire single-photon detectors (SNSPDs) have been demonstrated to offer superior performance in detection efficiency, timing resolution, and count rates over semiconductor photodetectors, and are a suitable technology for high photon efficiency links. Recently photon detectors based on superconducting nanowires have become commercially available, and we have assessed the characteristics and performance of one such commercial system as a candidate for potential utilization in ground receiver designs. The SNSPD system features independent channels which can be added modularly, and we analyze the scalability of the system to support different data rates, as well as consider coupling concepts and issues as the number of channels increases.

  13. Controlling abruptly autofocusing vortex beams to mitigate crosstalk and vortex splitting in free-space optical communication.

    Yan, Xu; Guo, Lixin; Cheng, Mingjian; Li, Jiangting

    2018-05-14

    Orbital angular momentum (OAM) mode crosstalk induced by atmospheric turbulence is a challenging phenomenon commonly occurring in OAM-based free-space optical (FSO) communication. Recent advances have facilitated new practicable methods using abruptly autofocusing light beams for weakening the turbulence effect on the FSO link. In this work, we show that a circular phase-locked Airy vortex beam array (AVBA) with sufficient elements has the inherent ability to form an abruptly autofocusing light beam carrying OAM, and its focusing properties can be controlled on demand by adjusting the topological charge values and locations of these vortices embedded in the array elements. The performance of a tailored Airy vortex beam array (TAVBA) through atmospheric turbulence is numerically studied. In a comparison with the ring Airy vortex beam (RAVB), the results indicate that TAVBA can be a superior light source for effectively reducing the intermodal crosstalk and vortex splitting, thus leading to improvement in the FSO system performance.

  14. Space-Time Turbo Trellis Coded Modulation for Wireless Data Communications

    Welly Firmanto

    2002-05-01

    Full Text Available This paper presents the design of space-time turbo trellis coded modulation (ST turbo TCM for improving the bandwidth efficiency and the reliability of future wireless data networks. We present new recursive space-time trellis coded modulation (STTC which outperform feedforward STTC proposed in by Tarokh et al. (1998 and Baro et al. (2000 on slow and fast fading channels. A substantial improvement in performance can be obtained by constructing ST turbo TCM which consists of concatenated recursive STTC, decoded by iterative decoding algorithm. The proposed recursive STTC are used as constituent codes in this scheme. They have been designed to satisfy the design criteria for STTC on slow and fast fading channels, derived for systems with the product of transmit and receive antennas larger than 3. The proposed ST turbo TCM significantly outperforms the best known STTC on both slow and fast fading channels. The capacity of this scheme on fast fading channels is less than 3 dB away from the theoretical capacity bound for multi-input multi-output (MIMO channels.

  15. The Joint Space Operations Center Mission System and the Advanced Research, Collaboration, and Application Development Environment Status Update 2016

    Murray-Krezan, Jeremy; Howard, Samantha; Sabol, Chris; Kim, Richard; Echeverry, Juan

    2016-05-01

    The Joint Space Operations Center (JSpOC) Mission System (JMS) is a service-oriented architecture (SOA) infrastructure with increased process automation and improved tools to enhance Space Situational Awareness (SSA) performed at the US-led JSpOC. The Advanced Research, Collaboration, and Application Development Environment (ARCADE) is a test-bed maintained and operated by the Air Force to (1) serve as a centralized test-bed for all research and development activities related to JMS applications, including algorithm development, data source exposure, service orchestration, and software services, and provide developers reciprocal access to relevant tools and data to accelerate technology development, (2) allow the JMS program to communicate user capability priorities and requirements to developers, (3) provide the JMS program with access to state-of-the-art research, development, and computing capabilities, and (4) support JMS Program Office-led market research efforts by identifying outstanding performers that are available to shepherd into the formal transition process. In this paper we will share with the international remote sensing community some of the recent JMS and ARCADE developments that may contribute to greater SSA at the JSpOC in the future, and share technical areas still in great need.

  16. Drone swarm with free-space optical communication to detect and make deep decisions about physical problems for area surveillance

    Mazher, Wamidh Jalil; Ibrahim, Hadeel T.; Ucan, Osman N.; Bayat, Oguz

    2018-03-01

    This paper aims to design a drone swarm network by employing free-space optical (FSO) communication for detecting and deep decision making of topological problems (e.g., oil pipeline leak), where deep decision making requires the highest image resolution. Drones have been widely used for monitoring and detecting problems in industrial applications during which the drone sends images from the on-air camera video stream using radio frequency (RF) signals. To obtain higher-resolution images, higher bandwidth (BW) is required. The current study proposed the use of the FSO communication system to facilitate higher BW for higher image resolution. Moreover, the number of drones required to survey a large physical area exceeded the capabilities of RF technologies. Our configuration of the drones is V-shaped swarm with one leading drone called mother drone (DM). The optical decode-and-forward (DF) technique is used to send the optical payloads of all drones in V-shaped swarm to the single ground station through DM. Furthermore, it is found that the transmitted optical power (Pt) is required for each drone based on the threshold outage probability of FSO link failure among the onboard optical-DF drones. The bit error rate of optical payload is calculated based on optical-DF onboard processing. Finally, the number of drones required for different image resolutions based on the size of the considered topological area is optimized.

  17. Orbital Angular Momentum-based Space Division Multiplexing for High-capacity Underwater Optical Communications

    Ren, Yongxiong; Li, Long; Wang, Zhe; Kamali, Seyedeh Mahsa; Arbabi, Ehsan; Arbabi, Amir; Zhao, Zhe; Xie, Guodong; Cao, Yinwen; Ahmed, Nisar; Yan, Yan; Liu, Cong; Willner, Asher J.; Ashrafi, Solyman; Tur, Moshe; Faraon, Andrei; Willner, Alan E.

    2016-09-01

    To increase system capacity of underwater optical communications, we employ the spatial domain to simultaneously transmit multiple orthogonal spatial beams, each carrying an independent data channel. In this paper, we show up to a 40-Gbit/s link by multiplexing and transmitting four green orbital angular momentum (OAM) beams through a single aperture. Moreover, we investigate the degrading effects of scattering/turbidity, water current, and thermal gradient-induced turbulence, and we find that thermal gradients cause the most distortions and turbidity causes the most loss. We show systems results using two different data generation techniques, one at 1064 nm for 10-Gbit/s/beam and one at 520 nm for 1-Gbit/s/beam; we use both techniques since present data-modulation technologies are faster for infrared (IR) than for green. For the 40-Gbit/s link, data is modulated in the IR, and OAM imprinting is performed in the green using a specially-designed metasurface phase mask. For the 4-Gbit/s link, a green laser diode is directly modulated. Finally, we show that inter-channel crosstalk induced by thermal gradients can be mitigated using multi-channel equalisation processing.

  18. TanDEM-X the Earth surface observation project from space level - basis and mission status

    Jerzy Wiśniowski

    2015-03-01

    Full Text Available TanDEM-X is DLR (Deutsches Zentrum für Luft- und Raumfahrt the Earth surface observation project using high-resolution SAR interferometry. It opens a new era in space borne radar remote sensing. The system is based on two satellites: TerraSAR-X (TSX and TanDEM-X (TDX flying on the very close, strictly controlled orbits. This paper gives an overview of the radar technology and overview of the TanDEM-X mission concept which is based on several innovative technologies. The primary objective of the mission is to deliver a global digital elevation model (DEM with an unprecedented accuracy, which is equal to or surpass the HRTI-3 specifications (12 m posting, relative height accuracy ±2 m for slope < 20% and ±4 m for slope > 20% [8]. Beyond that, TanDEM-X provides a highly reconfigurable platform for the demonstration of new radar imaging techniques and applications.[b]Keywords[/b]: remote sensing, Bistatic SAR, digital elevation model (DEM, Helix formation, SAR interferomery, HRTI-3, synchronization

  19. Free-Space Optical Communications: Capacity Bounds, Approximations, and a New Sphere-Packing Perspective

    Chaaban, Anas; Morvan, Jean-Marie; Alouini, Mohamed-Slim

    2016-01-01

    The capacity of the free-space optical channel is studied. A new recursive approach for bounding the capacity of the channel based on sphere-packing is proposed. This approach leads to new capacity upper bounds for a channel with a peak intensity constraint or an average intensity constraint. Under an average constraint only, the derived bound is tighter than an existing sphere-packing bound derived earlier by Farid and Hranilovic. The achievable rate of a truncated-Gaussian input distribution is also derived. It is shown that under both average and peak constraints, this achievable rate and the sphere-packing bounds are within a small gap at high SNR, leading to a simple high-SNR capacity approximation. Simple fitting functions that capture the best known achievable rate for the channel are provided. These functions can be of practical importance especially for the study of systems operating under atmospheric turbulence and misalignment conditions.

  20. Free-Space Optical Communications: Capacity Bounds, Approximations, and a New Sphere-Packing Perspective

    Chaaban, Anas

    2016-02-03

    The capacity of the free-space optical channel is studied. A new recursive approach for bounding the capacity of the channel based on sphere-packing is proposed. This approach leads to new capacity upper bounds for a channel with a peak intensity constraint or an average intensity constraint. Under an average constraint only, the derived bound is tighter than an existing sphere-packing bound derived earlier by Farid and Hranilovic. The achievable rate of a truncated-Gaussian input distribution is also derived. It is shown that under both average and peak constraints, this achievable rate and the sphere-packing bounds are within a small gap at high SNR, leading to a simple high-SNR capacity approximation. Simple fitting functions that capture the best known achievable rate for the channel are provided. These functions can be of practical importance especially for the study of systems operating under atmospheric turbulence and misalignment conditions.

  1. Free-space optical communications with peak and average constraints: High SNR capacity approximation

    Chaaban, Anas

    2015-09-07

    The capacity of the intensity-modulation direct-detection (IM-DD) free-space optical channel with both average and peak intensity constraints is studied. A new capacity lower bound is derived by using a truncated-Gaussian input distribution. Numerical evaluation shows that this capacity lower bound is nearly tight at high signal-to-noise ratio (SNR), while it is shown analytically that the gap to capacity upper bounds is a small constant at high SNR. In particular, the gap to the high-SNR asymptotic capacity of the channel under either a peak or an average constraint is small. This leads to a simple approximation of the high SNR capacity. Additionally, a new capacity upper bound is derived using sphere-packing arguments. This bound is tight at high SNR for a channel with a dominant peak constraint.

  2. Communicating LightSail: Embedded Reporting and Web Strategies for Citizen-Funded Space Missions

    Hilverda, M.; Davis, J.

    2015-12-01

    The Planetary Society (TPS) is a non-profit space advocacy group with a stated mission to "empower the world's citizens to advance space science and exploration." In 2009, TPS began work on LightSail, a small, citizen-funded spacecraft to demonstrate solar sailing propulsion technology. The program included a test flight, completed in June 2015, with a primary mission slated for late 2016. TPS initiated a LightSail public engagement campaign to provide the public with transparent mission updates, and foster educational outreach. A credentialed science journalist was given unrestricted access to the team and data, and provided regular reports without editorial oversight. An accompanying website, sail.planetary.org, provided project updates, multimedia, and real-time spacecraft data during the mission. Design approaches included a clean layout with text optimized for easy reading, balanced by strong visual elements to enhance reader comprehension and interest. A dedicated "Mission Control" page featured social media feeds, links to most recent articles, and a ground track showing the spacecraft's position, including overflight predictions based on user location. A responsive, cross-platform design allowed easy access across a broad range of devices. Efficient web server performance was prioritized by implementing a static content management system (CMS). Despite two spacecraft contingencies, the test mission successfully completed its primary objective of solar sail deployment. Qualitative feedback on the transparent, embedded reporting style was positive, and website metrics showed high user retention times. The website also grew awareness and support for the primary 2016 mission, driving traffic to a Kickstarter campaign that raised $1.24 million. Websites constantly evolve, and changes for the primary mission will include a new CMS to better support multiple authors and a custom dashboard to display real-time spacecraft sensor data.

  3. Communication of carrier status information following universal newborn screening for sickle cell disorders and cystic fibrosis: qualitative study of experience and practice.

    Kai, J; Ulph, F; Cullinan, T; Qureshi, N

    2009-11-01

    To describe and explore current practice, methods and experience of communicating carrier status information following newborn screening for cystic fibrosis (CF) and sickle cell (SC) disorders, to inform practice and further research. Three linked qualitative studies. All nine health regions in England. Child health screening coordinators in all English health regions, health professionals communicating results to parents and parents of newborn carriers. A preliminary phase of semi-structured telephone interviews with child health screening coordinators in all nine English health regions, and thematic analysis of data; semi-structured face-to-face interviews with purposeful samples of 67 family members of 51 infants identified by universal newborn screening as carriers of CF or SC with data analysis by constant comparison; and semi-structured telephone interviews, and focus groups, with a key informant sample of 16 differing health professionals currently tasked with communicating results to parents in a range of ways, with thematic analysis of data. Methods for and respondents' experiences of communication of carrier results varied considerably within and between regions, and within and between SC and CF contexts. Approaches ranged from letter or telephone call alone, to in-person communication in the clinic or at home, with health professionals from haemoglobinopathy, CF, screening and genetics backgrounds, or from community and primary care, such as health visitors with SC carrier results. Health professionals identified pros and cons of different methods, preferring opportunity for face-to-face communication with parents where possible, particularly for CF carrier results. They were concerned by regional variations in protocols, the lack of availability of translated information on SC carrier results, and the feasibility of sustaining more 'specialist' involvement at current levels, particularly for SC carriers. Parents were often poorly prepared for the

  4. Channel correlation of free space optical communication systems with receiver diversity in non-Kolmogorov atmospheric turbulence

    Ma, Jing; Fu, Yulong; Tan, Liying; Yu, Siyuan; Xie, Xiaolong

    2018-05-01

    Spatial diversity as an effective technique to mitigate the turbulence fading has been widely utilized in free space optical (FSO) communication systems. The received signals, however, will suffer from channel correlation due to insufficient spacing between component antennas. In this paper, the new expressions of the channel correlation coefficient and specifically its components (the large- and small-scale channel correlation coefficients) for a plane wave with aperture effects are derived for horizontal link in moderate-to-strong turbulence, using a non-Kolmogorov spectrum that has a generalized power law in the range of 3-4 instead of the fixed classical Kolmogorov power law of 11/3. And then the influence of power law variations on the channel correlation coefficient and its components are analysed. The numerical results indicated that various value of the power law lead to varying effects on the channel correlation coefficient and its components. This work will help with the further investigation on the fading correlation in spatial diversity systems.

  5. On the Performance of Free-Space Optical Communication Systems over Double Generalized Gamma Channel

    Al-Quwaiee, Hessa; Ansari, Imran Shafique; Alouini, Mohamed-Slim

    2015-01-01

    Starting with the double generalized Gamma (GG) model to describe turbulence-induced fading in free-space optical (FSO) systems, we propose a new unified model that accounts for the impact of pointing errors and type of receiver detector. More specifically, we present unified closed-form expressions for the cumulative distribution function, the probability density function, the moment generating function, and the moments of the end-toend signal-to-noise ratio (SNR) of a single link FSO transmission system in terms of the Meijer’s G-function. We then use these unified expressions to evaluate performance measures such as the bit error rate, the outage probability, and the ergodic capacity of (i) a single FSO link operating over double GG fading model (ii) asymmetric RF-FSO dual-hop relay transmission system with fixed gain relay. Using an asymptotic expansion of the Meijer’s G-function at high SNR, we express all the expressions, derived earlier, in terms of elementary functions. All our analytical results are verified using computer based Monte-Carlo simulations.

  6. On the Performance of Free-Space Optical Communication Systems over Double Generalized Gamma Channel

    Al-Quwaiee, Hessa

    2015-05-13

    Starting with the double generalized Gamma (GG) model to describe turbulence-induced fading in free-space optical (FSO) systems, we propose a new unified model that accounts for the impact of pointing errors and type of receiver detector. More specifically, we present unified closed-form expressions for the cumulative distribution function, the probability density function, the moment generating function, and the moments of the end-toend signal-to-noise ratio (SNR) of a single link FSO transmission system in terms of the Meijer’s G-function. We then use these unified expressions to evaluate performance measures such as the bit error rate, the outage probability, and the ergodic capacity of (i) a single FSO link operating over double GG fading model (ii) asymmetric RF-FSO dual-hop relay transmission system with fixed gain relay. Using an asymptotic expansion of the Meijer’s G-function at high SNR, we express all the expressions, derived earlier, in terms of elementary functions. All our analytical results are verified using computer based Monte-Carlo simulations.

  7. Adaptive Space-Time-Spreading-Assisted Wideband CDMA Systems Communicating over Dispersive Nakagami- Fading Channels

    Yang Lie-Liang

    2005-01-01

    Full Text Available In this contribution, the performance of wideband code-division multiple-access (W-CDMA systems using space-time-spreading- (STS- based transmit diversity is investigated, when frequency-selective Nakagami- fading channels, multiuser interference, and background noise are considered. The analysis and numerical results suggest that the achievable diversity order is the product of the frequency-selective diversity order and the transmit diversity order. Furthermore, both the transmit diversity and the frequency-selective diversity have the same order of importance. Since W-CDMA signals are subjected to frequency-selective fading, the number of resolvable paths at the receiver may vary over a wide range depending on the transmission environment encountered. It can be shown that, for wireless channels where the frequency selectivity is sufficiently high, transmit diversity may be not necessitated. Under this case, multiple transmission antennas can be leveraged into an increased bitrate. Therefore, an adaptive STS-based transmission scheme is then proposed for improving the throughput of W-CDMA systems. Our numerical results demonstrate that this adaptive STS-based transmission scheme is capable of significantly improving the effective throughput of W-CDMA systems. Specifically, the studied W-CDMA system's bitrate can be increased by a factor of three at the modest cost of requiring an extra 0.4 dB or 1.2 dB transmitted power in the context of the investigated urban or suburban areas, respectively.

  8. Free-Space Optical Communications: Capacity Bounds, Approximations, and a New Sphere-Packing Perspective

    Chaaban, Anas

    2015-04-01

    The capacity of the intensity-modulation direct-detection (IM-DD) free-space optical channel is studied. It is shown that for an IM-DD channel with generally input-dependent noise, the worst noise at high SNR is input-independent Gaussian with variance dependent on the input cost. Based on this result, a Gaussian IM-DD channel model is proposed where the noise variance depends on the optical intensity constraints only. A new recursive approach for bounding the capacity of the channel based on sphere-packing is proposed, which leads to a tighter bound than an existing sphere-packing bound for the channel with only an average intensity constraint. Under both average and peak constraints, it yields bounds that characterize the high SNR capacity within a negligible gap, where the achievability is proved by using a truncated Gaussian input distribution. This completes the high SNR capacity characterization of the channel, by closing the gap in the existing characterization for a small average-to-peak ratio. Simple fitting functions that capture the best known achievable rate for the channel are provided. These functions can be of significant practical importance especially for the study of systems operating under atmospheric turbulence and misalignment conditions. Finally, the capacity/SNR loss between heterodyne detection (HD) systems and IM-DD systems is bounded at high SNR, where it is shown that the loss grows as SNR increases for a complex-valued HD system, while it is bounded by 1.245 bits or 3.76 dB at most for a real-valued one.

  9. Free-Space Optical Communications: Capacity Bounds, Approximations, and a New Sphere-Packing Perspective

    Chaaban, Anas; Morvan, Jean-Marie; Alouini, Mohamed-Slim

    2015-01-01

    The capacity of the intensity-modulation direct-detection (IM-DD) free-space optical channel is studied. It is shown that for an IM-DD channel with generally input-dependent noise, the worst noise at high SNR is input-independent Gaussian with variance dependent on the input cost. Based on this result, a Gaussian IM-DD channel model is proposed where the noise variance depends on the optical intensity constraints only. A new recursive approach for bounding the capacity of the channel based on sphere-packing is proposed, which leads to a tighter bound than an existing sphere-packing bound for the channel with only an average intensity constraint. Under both average and peak constraints, it yields bounds that characterize the high SNR capacity within a negligible gap, where the achievability is proved by using a truncated Gaussian input distribution. This completes the high SNR capacity characterization of the channel, by closing the gap in the existing characterization for a small average-to-peak ratio. Simple fitting functions that capture the best known achievable rate for the channel are provided. These functions can be of significant practical importance especially for the study of systems operating under atmospheric turbulence and misalignment conditions. Finally, the capacity/SNR loss between heterodyne detection (HD) systems and IM-DD systems is bounded at high SNR, where it is shown that the loss grows as SNR increases for a complex-valued HD system, while it is bounded by 1.245 bits or 3.76 dB at most for a real-valued one.

  10. All-optical two-way relaying free-space optical communications for HAP-based broadband backhaul networks

    Vu, Minh Q.; Nguyen, Nga T. T.; Pham, Hien T. T.; Dang, Ngoc T.

    2018-03-01

    High-altitude platforms (HAPs) are flexible, non-pollutant and cost-effective infrastructures compared to satellite or old terrestrial systems. They are being researched and developed widely in Europe, USA, Japan, Korea, and so on. However, the current limited data rates and the overload of radio frequency (RF) spectrum are problems which the developers for HAPs are confronting because most of them use RF links to communicate with the ground stations (GSs) or each other. In this paper, we propose an all-optical two-way half-duplex relaying free-space optical (FSO) communication for HAP-based backhaul networks, which connect the base transceiver station (BTS) to the core network (CN) via a single HAP. Our proposed backhaul solution can be deployed quickly and flexibly for disaster relief and for serving users in both urban environments and remote areas. The key subsystem of HAP is an optical regenerate-and-forward (ORF) equipped with an optical hard-limiter (OHL) and an optical XOR gate to perform all-optical processing and help mitigate the background noise. In addition, two-way half-duplex relaying can be provided thanks to the use of network coding scheme. The closed-form expression for the bit error rate (BER) of our proposed system under the effect of path loss, atmospheric turbulence, and noise induced by the background light is formulated. The numerical results are demonstrated to prove the feasibility of our proposed system with the verification by using Monte-Carlo (M-C) simulations.

  11. Body as First Space of Communication: The Tonic-Emotional Dialogue in the Beginning of Psychic Life

    Rui Martins

    2015-11-01

    Full Text Available In the early stages of ontogenesis, when thesupport for development relies upon the relational function of the mother–baby dyad, the child will organise the foundation of the Self. This process involves a physiological and emotional symbiosis, in a relation with predominance of a tonic-emotional dialogue. The presence or absence of the other, the dynamics of nearness/farness, the postural and gestural dynamics, the containment activities, rhythmic synchronicities and thermal contact, are essential supports to primary organization of the psyche. When these processes are inadequate, they can cause problems of individuation and affirmation of identity, linked to absences or deficiencies in the primary relationship between mother and baby. This perspective leads us to equate the importance of corporeality in the early processes of communication when they are mediated primarily by tonic-emotional processes of communication, imbued with affections, desires and emotions. These processes are essential to the organization of the internal processes that make up this pre-linguistic phase, based on the organization of body schema, ensuring a sense of identity and the possibility of individuation and differentiation from the maternal object. When there are disruptions in this evolutionary dynamics, psychomotor therapy is a privileged resource, providing a safe and container space in which through spontaneous and symbolic play, children learn to transform the feelings, acts and affections in thoughts, projects and words. A desired relationship, allows to experience new forms of expression and conflict resolution, improving emotional and behavioural regulation, and promoting mentoring capacity and executive functions (such as attention, working memory, planning and inhibition of impulses.

  12. ScienceToGo.org: The Strengths and Weaknesses of Communicating Climate Change through Mass Transit Advertising Spaces

    Lustick, D. S.; Lohmeier, J.; Chen, R. F.; Wilson, R.; Rabkin, D.; Thompson, S. R.

    2016-02-01

    Engaging urban populations with climate change science is a difficult challenge since cities can seem so removed from the `natural environment.' However, mass transit provides an inherent means of communicating environmental messages with a cross section of the urban population. The Out of Home Media (OHM) spaces found on platforms and inside train cars provide a potentially effective means of bringing informal science learning opportunities directly to an underserved STEM audience. Our team felt that any messaging curriculum for a coastal urban subway system must complement the scary reality of the impacts of a changing climate (i.e. rising sea levels) with current examples of how the city is preparing for a more sustainable future. Urban areas such as Boston must develop adaptation and mitigation strategies that will help them not only survive, but thrive in a changing environment. In 2013-14, ScienceToGo.org ran a series of 12 engaging posters and placards staring `Ozzie the Ostrich' on the Massachusetts Bay Transit Authority's Red and Orange subway lines targeting an audience of more than 400,000 riders per day. The 12 month curriculum was divided into three phases: reality, relevance, and hope. During the presentation, we will present the results of our quasi-experimental research which identifies, quantifies, and explains the observed impacts of the campaign on adult riders. The strengths and weaknesses of the communication strategy will be discussed. Finally, we will conclude with some recommendations for how this work could improve and inform other urban informal science learning initiatives.

  13. A 2 x 2 imaging MIMO system based on LED Visible Light Communications employing space balanced coding and integrated PIN array reception

    Li, Jiehui; Xu, Yinfan; Shi, Jianyang

    2016-01-01

    In this paper, we proposed a 2 x 2 imaging Multi-Input Multi-Output (MIMO)-Visible Light Communication (VLC) system by employing Space Balanced Coding (SBC) based on two RGB LEDs and integrated PIN array reception. We experimentally demonstrated 1.4-Gbit/s VLC transmission at a distance of 2.5 m...

  14. 12.5 Gb/s multi-channel broadcasting transmission for free-space optical communication based on the optical frequency comb module.

    Tan, Jun; Zhao, Zeping; Wang, Yuehui; Zhang, Zhike; Liu, Jianguo; Zhu, Ninghua

    2018-01-22

    A wide-spectrum, ultra-stable optical frequency comb (OFC) module with 100 GHz frequency intervals based on a quantum dot mode locked (QDML) laser is fabricated by our lab, and a scheme with 12.5 Gb/s multi-channel broadcasting transmission for free-space optical (FSO) communication is proposed based on the OFC module. The output power of the OFC is very stable, with the specially designed circuit and the flatness of the frequency comb over the span of 6 nm, which can be limited to 1.5 dB. Four channel wavelengths are chosen to demonstrate one-to-many channels for FSO communication, like optical wireless broadcast. The outdoor experiment is established to test the bit error rate (BER) and eye diagrams with 12.5 Gb/s on-off keying (OOK). The indoor experiment is used to test the highest traffic rate, which is up to 21 Gb/s for one-hop FSO communication. To the best of our knowledge, this scheme is the first to propose the realization of one-to-many broadcasting transmission for FSO communication based on the OFC module. The advantages of integration, miniaturization, channelization, low power consumption, and unlimited bandwidth of one-to-many broadcasting communication scheme, shows promising results on constructing the future space-air-ground-ocean (SAGO) FSO communication networks.

  15. Adaptive optics correction into single mode fiber for a low Earth orbiting space to ground optical communication link using the OPALS downlink.

    Wright, Malcolm W; Morris, Jeffery F; Kovalik, Joseph M; Andrews, Kenneth S; Abrahamson, Matthew J; Biswas, Abhijit

    2015-12-28

    An adaptive optics (AO) testbed was integrated to the Optical PAyload for Lasercomm Science (OPALS) ground station telescope at the Optical Communications Telescope Laboratory (OCTL) as part of the free space laser communications experiment with the flight system on board the International Space Station (ISS). Atmospheric turbulence induced aberrations on the optical downlink were adaptively corrected during an overflight of the ISS so that the transmitted laser signal could be efficiently coupled into a single mode fiber continuously. A stable output Strehl ratio of around 0.6 was demonstrated along with the recovery of a 50 Mbps encoded high definition (HD) video transmission from the ISS at the output of the single mode fiber. This proof of concept demonstration validates multi-Gbps optical downlinks from fast slewing low-Earth orbiting (LEO) spacecraft to ground assets in a manner that potentially allows seamless space to ground connectivity for future high data-rates network.

  16. An Overview of Scientific and Space Weather Results from the Communication/Navigation Outage Forecasting System (C/NOFS) Mission

    Pfaff, R.; de la Beaujardiere, O.; Hunton, D.; Heelis, R.; Earle, G.; Strauss, P.; Bernhardt, P.

    2012-01-01

    The Communication/Navigation Outage Forecasting System (C/NOFS) Mission of the Air Force Research Laboratory is described. C/NOFS science objectives may be organized into three categories: (1) to understand physical processes active in the background ionosphere and thermosphere in which plasma instabilities grow; (2) to identify mechanisms that trigger or quench the plasma irregularities responsible for signal degradation; and (3) to determine how the plasma irregularities affect the propagation of electromagnetic waves. The satellite was launched in April, 2008 into a low inclination (13 deg), elliptical (400 x 850 km) orbit. The satellite sensors measure the following parameters in situ: ambient and fluctuating electron densities, AC and DC electric and magnetic fields, ion drifts and large scale ion composition, ion and electron temperatures, and neutral winds. C/NOFS is also equipped with a GPS occultation receiver and a radio beacon. In addition to the satellite sensors, complementary ground-based measurements, theory, and advanced modeling techniques are also important parts of the mission. We report scientific and space weather highlights of the mission after nearly four years in orbit

  17. Two-stage cross-talk mitigation in an orbital-angular-momentum-based free-space optical communication system.

    Qu, Zhen; Djordjevic, Ivan B

    2017-08-15

    We propose and experimentally demonstrate a two-stage cross-talk mitigation method in an orbital-angular-momentum (OAM)-based free-space optical communication system, which is enabled by combining spatial offset and low-density parity-check (LDPC) coded nonuniform signaling. Different from traditional OAM multiplexing, where the OAM modes are centrally aligned for copropagation, the adjacent OAM modes (OAM states 2 and -6 and OAM states -2 and 6) in our proposed scheme are spatially offset to mitigate the mode cross talk. Different from traditional rectangular modulation formats, which transmit equidistant signal points with uniform probability, the 5-quadrature amplitude modulation (5-QAM) and 9-QAM are introduced to relieve cross-talk-induced performance degradation. The 5-QAM and 9-QAM formats are based on the Huffman coding technique, which can potentially achieve great cross-talk tolerance by combining them with corresponding nonbinary LDPC codes. We demonstrate that cross talk can be reduced by 1.6 dB and 1 dB via spatial offset for OAM states ±2 and ±6, respectively. Compared to quadrature phase shift keying and 8-QAM formats, the LDPC-coded 5-QAM and 9-QAM are able to bring 1.1 dB and 5.4 dB performance improvements in the presence of atmospheric turbulence, respectively.

  18. High-Efficiency K-Band Space Traveling-Wave Tube Amplifier for Near-Earth High Data Rate Communications

    Simons, Rainee N.; Force, Dale A.; Spitsen, Paul C.; Menninger, William L.; Robbins, Neal R.; Dibb, Daniel R.; Todd, Phillip C.

    2010-01-01

    The RF performance of a new K-Band helix conduction cooled traveling-wave tube amplifier (TWTA), is presented in this paper. A total of three such units were manufactured, tested and delivered. The first unit is currently flying onboard NASA's Lunar Reconnaissance Orbiter (LRO) spacecraft and has flawlessly completed over 2000 orbits around the Moon. The second unit is a proto-flight model. The third unit will fly onboard NASA's International Space Station (ISS) as a very compact and lightweight transmitter package for the Communications, Navigation and Networking Reconfigurable Testbed (CoNNeCT), which is scheduled for launch in 2011. These TWTAs were characterized over the frequencies 25.5 to 25.8 GHz. The saturated RF output power is greater than 40 W and the saturated RF gain is greater than 46 dB. The saturated AM-to-PM conversion is 3.5 /dB and the small signal gain ripple is 0.46 dB peak-to-peak. The overall efficiency of the TWTA, including that of the electronic power conditioner (EPC) is as high as 45%.

  19. Effects of Visual Communication Tool and Separable Status Display on Team Performance and Subjective Workload in Air Battle Management

    Schwartz, Daniel; Knott, Benjamin A; Galster, Scott M

    2008-01-01

    ... ambient cabin noise while performing several visual and manual tasks. The purpose of this study is to compare team performance and subjective workload on a simulated AWACS scenario, for two conditions of communication...

  20. ESA's satellite communications programme

    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.

  1. Satellite Communications

    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

  2. Model-based system-of-systems engineering for space-based command, control, communication, and information architecture design

    Sindiy, Oleg V.

    executing multi-purpose analysis studies is presented. These efforts are coupled to the generation of aggregate and time-dependent solution performance metrics via the hierarchical decomposition of objectives and the analytical recomposition of multi-attribute qualitative program drivers from quantifiable measures. This methodology was also applied to generate problem-specific solution structure evaluation metrics that facilitate the comparison of alternate solutions at a high level of aggregation, at lower levels of abstraction, and to relate options for design variables with associated performance values. For proof-of-capability demonstration, the selected application problem concerns the design of command, control, communication, and information (C3I) architecture services for a notional campaign of crewed and robotic lunar surface missions. The impetus for the work was the demonstration of using model-based SoSE for design of sustainable interoperability capabilities between all data and communication assets in extended lunar campaigns. A comprehensive Lunar C3I simulation tool was developed by a team of researchers at Purdue University in support of NASA's Constellation Program; the author of this dissertation was a key contributor to the creation of this tool and made modifications and extensions to key components relevant to the methodological concepts presented in this dissertation. The dissertation concludes with a presentation of example results based on the interrogation of the constructed Lunar C3I computational model. The results are based on a family of studies, structured around a trade-tree of architecture options, which were conducted to test the hypothesis that the SoSE approach is efficacious in the information-exchange architecture design in space exploration domain. Included in the family of proof-of-capability studies is a simulation of the Apollo 17 mission, which allows not only for partial verification and validation of the model, but also provides

  3. Parental Socioeconomic Status, Communication, and Children's Vocabulary Development: A Third-Generation Test of the Family Investment Model

    Sohr-Preston, Sara L.; Scaramella, Laura V.; Martin, Monica J.; Neppl, Tricia K.; Ontai, Lenna; Conger, Rand

    2013-01-01

    This third-generation, longitudinal study evaluated a family investment perspective on family socioeconomic status (SES), parental investments in children, and child development. The theoretical framework was tested for first-generation parents (G1), their children (G2), and the children of the second generation (G3). G1 SES was expected to…

  4. Design, Development and Pre-Flight Testing of the Communications, Navigation, and Networking Reconfigurable Testbed (Connect) to Investigate Software Defined Radio Architecture on the International Space Station

    Over, Ann P.; Barrett, Michael J.; Reinhart, Richard C.; Free, James M.; Cikanek, Harry A., III

    2011-01-01

    The Communication Navigation and Networking Reconfigurable Testbed (CoNNeCT) is a NASA-sponsored mission, which will investigate the usage of Software Defined Radios (SDRs) as a multi-function communication system for space missions. A softwaredefined radio system is a communication system in which typical components of the system (e.g., modulators) are incorporated into software. The software-defined capability allows flexibility and experimentation in different modulation, coding and other parameters to understand their effects on performance. This flexibility builds inherent redundancy and flexibility into the system for improved operational efficiency, real-time changes to space missions and enhanced reliability/redundancy. The CoNNeCT Project is a collaboration between industrial radio providers and NASA. The industrial radio providers are providing the SDRs and NASA is designing, building and testing the entire flight system. The flight system will be integrated on the Express Logistics Carrier (ELC) on the International Space Station (ISS) after launch on the H-IIB Transfer Vehicle in 2012. This paper provides an overview of the technology research objectives, payload description, design challenges and pre-flight testing results.

  5. NASA Electronic Parts and Packaging (NEPP): Space Qualification Guidelines of Optoelectronic and Photonic Devices for Optical Communication Systems

    Kim, Quiesup

    2001-01-01

    Key elements of space qualification of opto-electric and photonic optical devices were overviewed. Efforts were concentrated on the reliability concerns of the devices needed for potential applications in space environments. The ultimate goal for this effort is to gradually establish enough data to develop a space qualification plan of newly developed specific photonic parts using empirical and numerical models to assess the life-time and degradation of the devices for potential long term space missions.

  6. New developments at Hunveyor and Husar space probe model constructions in Hungarian Universities and Colleges: status report of 2008

    Hegzi, S.; Bérczi, Sz.; Hudoba, Gy.; Magyar, I.; Lang, A.; Istenes, Z.; Weidinger, T.; Tepliczky, I.; Varga, T.; Hargitai, H.

    2008-09-01

    Introduction Hunveyor and Husar space probe models are the main school robotics program in Hungary in the last decade initiated by our Cosmic Materials Space research Group (CMSRG). As a new form of planetary science education in Hungary students build their lander and rover robots and test them on test tables, carry out simulations, and go with their instruments to field works of planetary geology analog sites. Recently 10 groups work in this program and here is a status report about the new results. Planetary robot construction and simulations steps We summarized in 10 steps the main "constructional and industrial research and technology" description of planetary material studying and collecting by space probes (landers, rovers). We focused on the activity we began and teach to carry out at those steps. (Main planets considered were the Moon and Mars): 1. Reconnaissance and survey of the surface of a planet by orbital space probes (i.e. Lunar Orbiter, MGS, MRO etc.) Our studies: photogeology, geomorphology, preparations to cartography. 2. Mapping of the surface of the selected planet with geographical and stratigraphical methods. We (CMSRG) prepared thematic maps on Moon, Mercury, Mars, Venus [1] and Atlas (3) in the series [2,3]. 3. Identification of various surface materials by albedo, spectroscopic [4], thermal IR, identification and selection of the target sites. (in terrestrial analog sites during field works) 4. Planning the space probe system lander and rover working together (MPF-Sojourner type assembly). Planning of the Hunveyor and Husar models. 5. Construction and manufacturing lander and rover units. All Hunveyor groups built their models [5]. 6. Launching and traveling the space probes to the planetary surface. (No rocket building, we simulate [6] some events during the voyage only). 7. Measuring the planetary surface environment on the surface of target planet [7]. (CMSRG) groups carry out test-table measurements [8] and simulations, and later they

  7. Socioeconomic status and non-communicable disease behavioural risk factors in low-income and lower-middle-income countries: a systematic review.

    Allen, Luke; Williams, Julianne; Townsend, Nick; Mikkelsen, Bente; Roberts, Nia; Foster, Charlie; Wickramasinghe, Kremlin

    2017-03-01

    Non-communicable diseases are the leading global cause of death and disproportionately afflict those living in low-income and lower-middle-income countries (LLMICs). The association between socioeconomic status and non-communicable disease behavioural risk factors is well established in high-income countries, but it is not clear how behavioural risk factors are distributed within LLMICs. We aimed to systematically review evidence on the association between socioeconomic status and harmful use of alcohol, tobacco use, unhealthy diets, and physical inactivity within LLMICs. We searched 13 electronic databases, including Embase and MEDLINE, grey literature, and reference lists for primary research published between Jan 1, 1990, and June 30, 2015. We included studies from LLMICs presenting data on multiple measures of socioeconomic status and tobacco use, alcohol use, diet, and physical activity. No age or language restrictions were applied. We excluded studies that did not allow comparison between more or less advantaged groups. We used a piloted version of the Cochrane Effective Practice and Organisation of Care Group data collection checklist to extract relevant data at the household and individual level from the included full text studies including study type, methods, outcomes, and results. Due to high heterogeneity, we used a narrative approach for data synthesis. We used descriptive statistics to assess whether the prevalence of each risk factor varied significantly between members of different socioeconomic groups. The study protocol is registered with PROSPERO, number CRD42015026604. After reviewing 4242 records, 75 studies met our inclusion criteria, representing 2 135 314 individuals older than 10 years from 39 LLMICs. Low socioeconomic groups were found to have a significantly higher prevalence of tobacco and alcohol use than did high socioeconomic groups. These groups also consumed less fruit, vegetables, fish, and fibre than those of high

  8. Short communication: Characterizing metabolic and oxidant status of pastured dairy cows postpartum in an automatic milking system.

    Elischer, M F; Sordillo, L M; Siegford, J M; Karcher, E L

    2015-10-01

    The periparturient period represents a stressful time for dairy cows as they transition from late gestation to early lactation. Undesirable fluctuations in metabolites and impaired immune defense mechanisms near parturition can severely affect cow health and have residual effects on performance and longevity. Metabolic and oxidative stress profiles of multiparous and primiparous dairy cows in traditional parlor and feeding systems are well characterized, but status of these profiles in alternative management systems, such as grazing cows managed with an automatic milking system (AMS), are poorly characterized. Therefore, the objective of this case study was to characterize the metabolic and oxidant status of pastured cows milked with an AMS. It was hypothesized that primiparous and multiparous cows milked with an AMS would experience changes in oxidative and metabolic status after parturition; however, these changes would not impair cow health or production. Blood was collected from 14 multiparous and 8 primiparous Friesian-cross dairy cows at 1, 7, 14, and 21 d relative to calving for concentrations of insulin, glucose, nonesterified fatty acids (NEFA), β-hydroxybutyrate, reduced glutathione, oxidized glutathione, and antioxidant potential. Milk production and milking frequency data were collected postpartum. Milk production differed on d 7 and 14 between primiparous and multiparous cows and frequency was not affected by parity. Primiparous cows had higher levels of glucose than multiparous cows. No differences in insulin, NEFA, or β-hydroxybutyrate concentrations were noted between multiparous and primiparous cows postpartum, though days relative to calving significantly affected insulin and NEFA. Primiparous cows also had higher antioxidant potential than multiparous cows during the postpartum period. Results from this study show that, although responses were within expected ranges, periparturient multiparous cows responded differently than periparturient

  9. Status of the Space-Rated Lithium-Ion Battery Advanced Development Project in Support of the Exploration Vision

    Miller, Thomas

    2007-01-01

    The NASA Glenn Research Center (GRC), along with the Goddard Space Flight Center (GSFC), Jet Propulsion Laboratory (JPL), Johnson Space Center (JSC), Marshall Space Flight Center (MSFC), and industry partners, is leading a space-rated lithium-ion advanced development battery effort to support the vision for Exploration. This effort addresses the lithium-ion battery portion of the Energy Storage Project under the Exploration Technology Development Program. Key discussions focus on the lithium-ion cell component development activities, a common lithium-ion battery module, test and demonstration of charge/discharge cycle life performance and safety characterization. A review of the space-rated lithium-ion battery project will be presented highlighting the technical accomplishments during the past year.

  10. I-centric Communications

    Arbanowski, S; Steglich, S; Popescu-Zeletin, R

    2001-01-01

    During the last years, a variety of concepts for service integration and corresponding systems have gained momentum. On the one hand, they aim for the interworking and integration of classical telecommunications and data communications services. On the other hand, they are focusing on universal service access from a variety of end user systems. Looking at humans' communication behavior and communication space, it is obvious that human beings interact frequently in a set of contexts in their environment (communication space). Following this view, we want to build communication systems on the analysis of the individual communication spaces. The results are communication systems adapted to the specific demands of each individual. The authors introduce I-centric Communication Systems, an approach to design communication systems which adapt to the individual communication space and individual environment and situation. In this context "I" means I, or individual, "Centric" means adaptable to I requirements and a ce...

  11. AN/FSY-3 Space Fence System – Sensor Site One/Operations Center Integration Status and Sensor Site Two Planned Capability

    Fonder, G. P.; Hack, P. J.; Hughes, M. R.

    This paper covers two topics related to Space Fence System development: Sensor Site One / Operations Center construction and integration status including risk reduction integration and test efforts at the Moorestown, NJ Integrated Test Bed (ITB); and the planned capability of Sensor Site Two. The AN/FSY-3 Space Fence System is a ground-based system of S-band radars integrated with an Operations Center designed to greatly enhance the Air Force Space Surveillance network. The radar architecture is based on Digital Beam-forming. This capability permits tremendous user-defined flexibility to customize volume surveillance and track sectors instantaneously without impacting routine surveillance functions. Space Fence provides unprecedented sensitivity, coverage and tracking accuracy, and contributes to key mission threads with the ability to detect, track and catalog small objects in LEO, MEO and GEO. The system is net-centric and will seamlessly integrate into the existing Space Surveillance Network, providing services to external users—such as JSpOC—and coordinating handoffs to other SSN sites. Sensor Site One construction on the Kwajalein Atoll is in progress and nearing completion. The Operations Center in Huntsville, Alabama has been configured and will be integrated with Sensor Site One in the coming months. System hardware, firmware, and software is undergoing integration testing at the Mooretown, NJ ITB and will be deployed at Sensor Site One and the Operations Center. The preliminary design for Sensor Site Two is complete and will provide critical coverage, timeliness, and operational flexibility to the overall system.

  12. High Efficiency Traveling-Wave Tube Power Amplifier for Ka-Band Software Defined Radio on International Space Station-A Platform for Communications Technology Development

    Simons, Rainee N.; Force, Dale A.; Kacpura, Thomas J.

    2013-01-01

    The design, fabrication and RF performance of the output traveling-wave tube amplifier (TWTA) for a space based Ka-band software defined radio (SDR) is presented. The TWTA, the SDR and the supporting avionics are integrated to forms a testbed, which is currently located on an exterior truss of the International Space Station (ISS). The SDR in the testbed communicates at Ka-band frequencies through a high-gain antenna directed to NASA s Tracking and Data Relay Satellite System (TDRSS), which communicates to the ground station located at White Sands Complex. The application of the testbed is for demonstrating new waveforms and software designed to enhance data delivery from scientific spacecraft and, the waveforms and software can be upgraded and reconfigured from the ground. The construction and the salient features of the Ka-band SDR are discussed. The testbed is currently undergoing on-orbit checkout and commissioning and is expected to operate for 3 to 5 years in space.

  13. Decision Making and Communications Process Assessment of NASA Using Three Change Requests from the Space Launch System Program

    Hicks, Karen Campbell

    2015-01-01

    This thesis investigated the communication and decision making process as part of the Systems Engineering practices at the NASA/Marshall Center to determine its level of effectiveness. Data was collected across three change requests to assess how decisions were made, how the decisions were communicated, and whether a process mattered in the formulation and dissemination of those decisions. Data results revealed the comprehensive decision making process for the technical change requests to be effective. Evidence revealed that the process was sufficiently tailored to accommodate the need of each individual technical change which promoted effective communication amongst the stakeholders in the formulation of the strategic decision recommendations elevated to upper management. However, data results also revealed the dissemination of the final decision and approval of the change requests from the higher organizational level down to all stakeholders was less effective. An establishment of a culmination meeting at the end of the change request decision process in which to close the communication loop with all entities would be beneficial.

  14. What Are Preadolescent Readers Doing Online? An Examination of Upper Elementary Students' Reading, Writing, and Communication in Digital Spaces

    Hutchison, Amy C.; Woodward, Lindsay; Colwell, Jamie

    2016-01-01

    The online reading, writing, and communication practices of students have been of significant interest to literacy researchers and teachers throughout the last several years, as insights into what students are currently doing in and outside of school can inform what they can be expected to know and be able to do in digital environments. Yet,…

  15. SHORT COMMUNICATION: Status of Physical Fitness Index (PFI % and Anthropometric Parameters in Residential School Children Compared to Nonresidential School Children

    Jyoti P Khodnapur

    2012-07-01

    Full Text Available Background: Physical fitness is the prime criterion for survival, to achieve any goal and to lead a healthy life. Effect of exercise to have a good physical fitness is well known since ancient Vedas. Physical fitness can be recorded by cardiopulmonary efficiency test like Physical Fitness Index (PFI % which is a powerful indicator of cardiopulmonary efficiency. Regular exercise increases PFI by increasing oxygen consumption. Residential school children are exposed to regular exercise and nutritious food under the guidance. Aims and Objectives: Our study is aimed to compare the physical fitness index status and anthropometric parameters in Residential Sainik (n=100 school children compared to Non-Residential (n=100 school children (aged between 12-16 years of Bijapur. Material and Methods: PFI was measured by Harvard Step Test [1]. TheAnthropometrical parameters like Height (cms, Weight (Kg, Body Surface Area (BSA in sq.mts, Body Mass Index (BMI in Kg/m2, Mid Arm Circumference (cms, Chest Circumference (cms and Abdominal Circumference (cms were recorded. Results: Mean score of PFI(%, Height(cms, Weight(Kg, BSA(sq.mts, BMI(Kg/m2, Mid Arm Circumference(cms, Chest Circumference (cms and Abdominal Circumference (cms were significantly higher (p=0.000 in Residential school children compared to Non Residential school children. In conclusion regular exercise and nutritious diet under the guidance increases the physical fitness and growth in growing children.

  16. 78 FR 14952 - Earth Stations Aboard Aircraft Communicating with Fixed-Satellite Service Geostationary-Orbit...

    2013-03-08

    ... FEDERAL COMMUNICATIONS COMMISSION 47 CFR Part 2 [IB Docket No. 12-376; FCC 12-161] Earth Stations... (NPRM) seeks comment on a proposal to elevate the allocation status of Earth Stations Aboard Aircraft... with GSO space stations of the FSS on a primary basis in the 11.7-12.2 GHz band (space-to-Earth), on an...

  17. Current status and future prospect of space and time reversal symmetry violation on low energy neutron reactions

    Masuda, Yasuhiro

    1993-01-01

    In this report, the papers on symmetry violation under space reflection and time reversal and neutron spin, neutron spin rotation and P-violation, parity nonconservation in neutron capture reaction, some advantage of the search for CP-violation in neutron scattering, dynamic polarization of 139 La target, alexandrite laser for optical pumping, polarized 3 He system for T- and P-violation neutron experiments, control of neutron spin in T-violation neutron experiment, symmetry regarding time and space and angular distribution and angular correlation of radiation and particle beams, T-violation due to low temperature nuclear polarization and axion exploration using nuclear transition are collected. (K.I.)

  18. Working in a developing communication space. Facebook and Twitter as journalistic tools for European information pure-player websites

    Florian Tixier

    2014-06-01

    Full Text Available Since the creation of the European Union, European information has been a very important issue of communication. Numerous Europe-specialized information websites were born in the first decade of the 21st century, thus creating a European informational landscape on the Internet. In a context of journalistic technological and economical evolutions, journalists have to adapt rapidly their ways of working. A new function in terms of management of socio-numeric networks has appeared: community management. This research aims at analyzing the uses of Facebook and Twitter in the community management of online European information websites. We will be specifically observing how information makers integrate these technologies, which originally were not part of the journalistic work patterns, and how they use these new means of communication to circulate European ideas through self-promotion practices.

  19. WORKING IN A DEVELOPING COMMUNICATION SPACE. FACEBOOK AND TWITTER AS JOURNALISTIC TOOLS FOR EUROPEAN INFORMATION PURE-PLAYER WEBSITES

    Florian Tixier

    2014-06-01

    Full Text Available Since the creation of the European Union, European information has been a very important issue of communication. Numerous Europe-specialized information websites were born in the first decade of the 21st century, thus creating a European informational landscape on the Internet. In a context of journalistic technological and economical evolutions, journalists have to adapt rapidly their ways of working. A new function in terms of management of socio-numeric networks has appeared: community management. This research aims at analyzing the uses of Facebook and Twitter in the community management of online European information websites. We will be specifically observing how information makers integrate these technologies, which originally were not part of the journalistic work patterns, and how they use these new means of communication to circulate European ideas through self-promotion practices.

  20. Using the human eye to image space radiation or the history and status of the light flash phenomena

    Fuglesang, C [European Astronaut Centre, ESA, Cologne, Germany and Royal Institute of Technolgy (KTH), Stockholm (Sweden)], E-mail: Christer.fuglesang@esa.int

    2007-10-01

    About 80% of people who travel in space experience sudden phosphenes, commonly called light flashes (LF). Although the detailed physiological process is still not known, the LFs are caused by particles in the cosmic radiation field. Indeed, by counting LFs one can even make a crude image of the radiation environment around the Earth. Studies on the space station Mir with the SilEye experiment correlated LFs with charged particles traversing the eye. It was found that a nucleus in the radiation environment has roughly a 1% probability of causing a light flash, whereas the proton's probability is almost three orders of magnitude less. As a function of linear energy transfer (LET), the probability increased with ionization above 10 keV/{mu}m, reaching about 5% at 50 keV/{mu}m. The investigations are continuing on the International Space Station (ISS) with the Alteino/SileEye-3 detector, which is also a precursor to the large Anomalous Long Term Effects on Astronauts (ALTEA) facility. These detectors are also measuring-imaging-the radiation environment inside the ISS, which will be compared to Geant4 simulations from the DESIRE project. To further the understanding of the LF phenomena, a survey among current NASA and ESA astronauts was recently conducted. The LFs are predominantly noticed before sleep and some respondents even thought it disturbed their sleep. The LFs appear white, have elongated shapes, and most interestingly, often come with a sense of motion. Comparing the shapes quoted from space observations with ground experiments done by researchers in the 1970s, it seems likely that some 5-10% of the LFs in space are due to Cherenkov light in the eye. However, the majority is most likely caused by some direct interaction in the retina.