WorldWideScience

Sample records for satellite eyeing system

  1. Satellite eye for Galathea 3. Annual report 2007

    DEFF Research Database (Denmark)

    Hasager, Charlotte Bay; Sørensen, Peter Brøgger; Pedersen, Leif Toudal;

    with a short text was published each week at the homepage www.satelliteeye.dk . During 2007 the Satellite Eye team jointly with Nature & science prepared an educational film ‘Satellite Eye – Galathea 3 fra rummet’. This work is funded by The Danish Ministry of Education, Tips- og Lottopuljen. The film...

  2. Satellite Eye for Galathea 3. Annual report 2006

    DEFF Research Database (Denmark)

    Hasager, Charlotte Bay; Sørensen, Peter; Pedersen, Leif Toudal

    The Satellite Eye for Galathea 3 project is collecting satellite images from many satellites and, in particular, from the European ENVISAT satellite along the Galathea 3 global route. The expedition takes place from 11 August 2006 to 27 April 2007. Prior to the expedition several satellite images...... were collected from locations along the planned route. During the expedition large amounts of satellite images are collected and stored in a database. Most images can be viewed online through Google Earth along with the ship observations in near-real-time. This means that researchers onboard the ship...

  3. The Archimedes satellite system

    Science.gov (United States)

    Taylor, Stuart C.; Shurvinton, William D.

    1992-03-01

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

  4. China's Meteorological Satellite Application System

    Institute of Scientific and Technical Information of China (English)

    Zhang Jiashen

    2008-01-01

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

  5. Eyes on the Solar System

    Data.gov (United States)

    National Aeronautics and Space Administration — Eyes on the Solar System is a software package developed by NASA Jet Propulsion Laboratory and the California Institute of Technology using data provided by NASA's...

  6. Mapping soil heterogeneity using RapidEye satellite images

    Science.gov (United States)

    Piccard, Isabelle; Eerens, Herman; Dong, Qinghan; Gobin, Anne; Goffart, Jean-Pierre; Curnel, Yannick; Planchon, Viviane

    2016-04-01

    In the frame of BELCAM, a project funded by the Belgian Science Policy Office (BELSPO), researchers from UCL, ULg, CRA-W and VITO aim to set up a collaborative system to develop and deliver relevant information for agricultural monitoring in Belgium. The main objective is to develop remote sensing methods and processing chains able to ingest crowd sourcing data, provided by farmers or associated partners, and to deliver in return relevant and up-to-date information for crop monitoring at the field and district level based on Sentinel-1 and -2 satellite imagery. One of the developments within BELCAM concerns an automatic procedure to detect soil heterogeneity within a parcel using optical high resolution images. Such heterogeneity maps can be used to adjust farming practices according to the detected heterogeneity. This heterogeneity may for instance be caused by differences in mineral composition of the soil, organic matter content, soil moisture or soil texture. Local differences in plant growth may be indicative for differences in soil characteristics. As such remote sensing derived vegetation indices may be used to reveal soil heterogeneity. VITO started to delineate homogeneous zones within parcels by analyzing a series of RapidEye images acquired in 2015 (as a precursor for Sentinel-2). Both unsupervised classification (ISODATA, K-means) and segmentation techniques were tested. Heterogeneity maps were generated from images acquired at different moments during the season (13 May, 30 June, 17 July, 31 August, 11 September and 1 November 2015). Tests were performed using blue, green, red, red edge and NIR reflectances separately and using derived indices such as NDVI, fAPAR, CIrededge, NDRE2. The results for selected winter wheat, maize and potato fields were evaluated together with experts from the collaborating agricultural research centers. For a few fields UAV images and/or yield measurements were available for comparison.

  7. Integrated Satellite-HAP Systems

    DEFF Research Database (Denmark)

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

    2005-01-01

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

  8. Cooperative and cognitive satellite systems

    CERN Document Server

    Chatzinotas, Symeon; De Gaudenzi, Riccardo

    2015-01-01

    Cooperative and Cognitive Satellite Systems provides a solid overview of the current research in the field of cooperative and cognitive satellite systems, helping users understand how to incorporate state-of-the-art communication techniques in innovative satellite network architectures to enable the next generation of satellite systems. The book is edited and written by top researchers and practitioners in the field, providing a comprehensive explanation of current research that allows users to discover future technologies and their applications, integrate satellite and terrestrial systems

  9. Meteorological satellite systems

    CERN Document Server

    Tan, Su-Yin

    2014-01-01

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

  10. Spanish Earth Observation Satellite System

    Science.gov (United States)

    Borges, A.; Cerezo, F.; Fernandez, M.; Lomba, J.; Lopez, M.; Moreno, J.; Neira, A.; Quintana, C.; Torres, J.; Trigo, R.; Urena, J.; Vega, E.; Vez, E.

    2010-12-01

    The Spanish Ministry of Industry, Tourism and Trade (MITyC) and the Ministry of Defense (MoD) signed an agreement in 2007 for the development of a "Spanish Earth Observation Satellite System" based, in first instance, on two satellites: a high resolution optical satellite, called SEOSAT/Ingenio, and a radar satellite based on SAR technology, called SEOSAR/Paz. SEOSAT/Ingenio is managed by MITyC through the Centre for the Development of Industrial Technology (CDTI), with technical and contractual support from the European Space Agency (ESA). HISDESA T together with the Spanish Instituto Nacional de Técnica Aeroespacial (INTA, National Institute for Aerospace Technology) will be responsible for the in-orbit operation and the commercial operation of both satellites, and for the technical management of SEOSAR/Paz on behalf of the MoD. In both cases EADS CASA Espacio (ECE) is the prime contractor leading the industrial consortia. The ground segment development will be assigned to a Spanish consortium. This system is the most important contribution of Spain to the European Programme Global Monitoring for Environment and Security, GMES. This paper presents the Spanish Earth Observation Satellite System focusing on SEOSA T/Ingenio Programme and with special emphasis in the potential contribution to the ESA Third Party Missions Programme and to the Global Monitoring for Environment and Security initiative (GMES) Data Access.

  11. Advanced satellite communication system

    Science.gov (United States)

    Staples, Edward J.; Lie, Sen

    1992-01-01

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

  12. Multiscale systems integration in the eye.

    Science.gov (United States)

    Jacobs, Marc D

    2009-01-01

    A series of research topics on the eye is reviewed with the aim of illustrating how integrative and systems-biological approaches can be used to understand complex properties and functions of ocular tissues. Emphasis is placed on the diversity of physiological systems represented in the eye, and the variety of approaches required to analyze those systems, both empirically and theoretically. Modeling and empirical studies reviewed focus mainly on problems that the eye presents, in the broad areas of biomechanics and fluid dynamics from the molecular to the whole-organ scale. Attention is given to the relevance of these studies in human disease and the current potential for development of medical therapies based upon a biophysical, integrative modeling approach. The creation of a multiscale hierarchy of numerical models of the eye is proposed as an important and unifying aim of integrative eye research.

  13. The Omninet mobile satellite system

    Science.gov (United States)

    Salmasi, A.; Curry, W.

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

  14. Satellite Attitude Control System Simulator

    Directory of Open Access Journals (Sweden)

    G.T. Conti

    2008-01-01

    Full Text Available Future space missions will involve satellites with great autonomy and stringent pointing precision, requiring of the Attitude Control Systems (ACS with better performance than before, which is function of the control algorithms implemented on board computers. The difficulties for developing experimental ACS test is to obtain zero gravity and torque free conditions similar to the SCA operate in space. However, prototypes for control algorithms experimental verification are fundamental for space mission success. This paper presents the parameters estimation such as inertia matrix and position of mass centre of a Satellite Attitude Control System Simulator (SACSS, using algorithms based on least square regression and least square recursive methods. Simulations have shown that both methods have estimated the system parameters with small error. However, the least square recursive methods have performance more adequate for the SACSS objectives. The SACSS platform model will be used to do experimental verification of fundamental aspects of the satellite attitude dynamics and design of different attitude control algorithm.

  15. Satellite Eye for the Galathea 3 ship expedition: Global tour 2006-2007

    DEFF Research Database (Denmark)

    Hasager, Charlotte Bay; Badger, Merete; Sørensen, Peter

    2007-01-01

    Islands, New Zealand, Antarctica, Chile, Galapagos, the Caribbean, the Northeastern USA and finishing in Denmark 25 April 2007. During the entire expedition satellite images were ordered along the ship track, downloaded, processed, archived and used for education. The satellite images are displayed...... of the expedition and these classes in particular used the Satellite Eye teaching material. In Google Earth satellite images of many themes are shown. These include sea ice, sea surface temperature, ocean wind, wave height, sea surface level, ozone, clouds and radar images of ocean and land. Also high spatial...... resolution land cover mapping of the visited harbors and their surroundings are included. The case studies uses the image processing software LEOWorks developed through the ESA project EDUSPACE, the European Earth Observation web site for Secondary Schools (http://www.eduspace.esa.int. For each theme...

  16. Economics of satellite communications systems

    Science.gov (United States)

    Pritchard, Wilbur L.

    This paper is partly a tutorial, telling systematically how one goes about calculating the total annual costs of a satellite communications system, and partly the expression of some original ideas on the choice of parameters so as to minimize these costs. The calculation of costs can be divided into two broad categories. The first is technical and is concerned with estimating what particular equipment will cost and what will be the annual expense to maintain and operate it. One starts in the estimation of any new system by listing the principal items of equipment, such as satellites, earth stations of various sizes and functions, telemetry and tracking equipment and terrestrial interfaces, and then estimating how much each item will cost. Methods are presented for generating such estimates, based on a knowledge of the gross parameters, such as antenna size, coverage area, transmitter power and information rate. These parameters determine the system performance and it is usually possible, knowing them, to estimate the costs of the equipment rather well. Some formulae based on regression analyses are presented. Methods are then given for estimating closely related expenses, such as maintenance and operation, and then an approximate method is developed for estimating terrestrial interconnection costs. It is pointed out that in specific cases when tariff and geographical information are available, it is usually better to work with specific data, but nonetheless it is often desirable, especially in global system estimating, to approximate these interconnect costs without recourse to individual tariffs. The procedure results in a set of costs for the purchase of equipment and its maintenance, and a schedule of payments. Some payments will be incurred during the manufacture of the satellite and before any systems operation, but many will not be incurred until the system is no longer in use, e.g. incentives. In any case, with the methods presented in the first section, one

  17. An Analog VLSI Saccadic Eye Movement System

    OpenAIRE

    1994-01-01

    In an effort to understand saccadic eye movements and their relation to visual attention and other forms of eye movements, we - in collaboration with a number of other laboratories - are carrying out a large-scale effort to design and build a complete primate oculomotor system using analog CMOS VLSI technology. Using this technology, a low power, compact, multi-chip system has been built which works in real-time using real-world visual inputs. We describe in this paper the performance of a...

  18. Systems and methods of eye tracking calibration

    DEFF Research Database (Denmark)

    2014-01-01

    Methods and systems to facilitate eye tracking control calibration are provided. One or more objects are displayed on a display of a device, where the one or more objects are associated with a function unrelated to a calculation of one or more calibration parameters. The one or more calibration...

  19. Global navigation satellite systems and their applications

    CERN Document Server

    Madry, Scott

    2015-01-01

    Dr. Madry, one of the world's leading experts in the field, provides in a condensed form a quick yet comprehensive overview of satellite navigation. This book concisely addresses the latest technology, the applications, the regulatory issues, and the strategic implications of satellite navigation systems. This assesses the strengths and weaknesses of satellite navigation networks and review of all the various national systems now being deployed and the motivation behind the proliferation of these systems.

  20. Integration of mobile satellite and cellular systems

    Science.gov (United States)

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

    1993-01-01

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

  1. Effects on biological systems of reflected light from a satellite power system

    Science.gov (United States)

    White, M.

    1981-01-01

    Light reflection produced by the satellite power system and the possible effects of that light on the human eye, plants, and animals were studied. For the human eye, two cases of reflected light, might cause eye damage if viewed for too long. These cases are: (1) if, while in low Earth orbit, the orbital transfer vehicle is misaligned to reflect the Sun to Earth there exists a maximum safe fixation time for the naked eye of 42.4 secs; (2) reflection from the aluminum paint on the back of the orbital transfer vehicle, while in or near low Earth orbit, can be safely viewed by the naked eye for 129 sec. For plants and animals the intensity and timing of light are not a major problem. Ways for reducing and/or eliminating the irradiances are proposed.

  2. IMPLEMENTATION OF AERONAUTICAL LOCAL SATELLITE AUGMENTATION SYSTEM

    Directory of Open Access Journals (Sweden)

    Stojce Ilcev

    2011-03-01

    Full Text Available Abstract. This paper introduces development and implementation of new Local Satellite AugmentationSystem as an integration component of the Regional Satellite Augmentation System (RSAS employingcurrent and new Satellite Communications, Navigation and Surveillance (CNS for improvement of the AirTraffic Control (ATC and Air Traffic Management (ATM and for enhancement safety systems includingtransport security and control of flights in all stages, airport approaching, landing, departures and allmovements over airport surface areas. The current first generation of the Global Navigation Satellite SystemGNSS-1 applications are represented by fundamental military solutions for Position, Velocity and Time ofthe satellite navigation and determination systems such as the US GPS and Russian GLONASS (Former-USSR requirements, respectively. The establishment of Aeronautical CNS is also discussed as a part ofGlobal Satellite Augmentation Systems of GPS and GLONASS systems integrated with existing and futureRSAS and LSAS in airports areas. Specific influence and factors related to the Comparison of the Currentand New Aeronautical CNS System including the Integration of RSAS and GNSS solutions are discussedand packet of facts is determined to maximize the new satellite Automatic Dependent Surveillance System(ADSS and Special Effects of the RSAS Networks. The possible future integration of RSAS and GNSS andthe common proposal of the satellite Surface Movement Guidance and Control are presented in thechangeless ways as of importance for future enfacements of ATC and ATM for any hypothetical airportinfrastructure.Keywords: ADSS, ATC, ATM, CNS, GSAS, LRAS, RSAS, SMGC, Special Effects of RSAS.

  3. Design of the American Mobile Satellite System

    Science.gov (United States)

    Kittiver, Charles

    1991-01-01

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

  4. Integration of Mobil Satellite and Cellular Systems

    Science.gov (United States)

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

    1993-01-01

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

  5. Experimental millimeter-wave satellite communications system

    Science.gov (United States)

    Suzuki, Yoshiaki; Shimada, Masaaki; Arimoto, Yoshinori; Shiomi, Tadashi; Kitazume, Susumu

    This paper describes an experimental system of millimeter-wave satellite communications via Japan's Engineering Test Satellite-VI (ETS-VI) and a plan of experiments. Two experimental missions are planned using ETS-VI millimeter-wave (43/38 GHz bands) transponder, considering the millimeter-wave characteristics such as large transmission capacity and possibility to construct a small earth station with a high gain antenna. They are a personal communication system and an inter-satellite communication system. Experimental system including the configuration and the fundamental functions of the onboard transponder and the outline of the experiments are presented.

  6. Satellite Sanitary Systems in Kampala, Uganda

    NARCIS (Netherlands)

    Letema, S.; Van Vliet, B.; Van Lier, J.B.

    2011-01-01

    Satellite sewage collection and treatment systems have been independently developed and managed in East African cities outside the centrally planned and sewered areas. A satellite approach is a promising provisioning option parallel to public sewerage for middle- and high-income residential areas, e

  7. Satellite Sanitary Systems in Kampala, Uganda

    NARCIS (Netherlands)

    Letema, S.C.; Vliet, van B.J.M.; Lier, van J.B.

    2012-01-01

    Satellite sewage collection and treatment systems have been independently developed and managed in East African cities outside the centrally planned and sewered areas. A satellite approach is a promising provisioning option parallel to public sewerage for middle- and high-income residential areas, e

  8. Advanced tracking and data relay satellite system

    Science.gov (United States)

    Stern, Daniel

    1992-01-01

    The purpose of this communication satellite system are as follows: to provide NASA needs for satellite tracking and communications through the year 2012; to maintain and augment the current TDRS system when available satellite resources are expended in the latter part of the decade; to provide the necessary ground upgrade to support the augmented services; and to introduce new technology to reduce the system life cycle cost. It is concluded that no ATDRS spacecraft requirement for new modulation techniques, that data rate of 650 MBps is required, and that Space Station Freedom requirement is for 650 MBps data some time after the year 2000.

  9. Reliability Growth Analysis of Satellite Systems

    Science.gov (United States)

    2012-09-01

    obtained. In addition, the Cumulative Intensity Function ( CIF ) of a family of satellite systems was analyzed to assess its similarity to that of a...parameters are obtained. In addition, the Cumulative Intensity Function ( CIF ) of a family of satellite systems was analyzed to assess its similarity to that...System Figures 7a through 7i display the real CIF for a variety of GOES missions. These cumulative intensity functions have shapes similar to the

  10. The Cyclone Global Navigation Satellite System (CYGNSS) - Analysis and Data Assimilation for Tropical Convection

    Science.gov (United States)

    Li, Xuanli; Lang, Timothy J.; Mecikalski, John; Castillo, Tyler; Hoover, Kacie; Chronis, Themis

    2017-01-01

    Cyclone Global Navigation Satellite System (CYGNSS): a constellation of 8 micro-satellite observatories launched in November 2016, to measure near-surface oceanic wind speed. Main goal: To monitor surface wind fields of the Tropical Cyclones' inner core, including regions beneath the intense eye wall and rain bands that could not previously be measured from space; Cover 38 deg S -38 deg N with unprecedented temporal resolution and spatial coverage, under all precipitating conditions Low flying satellite: Pass over ocean surface more frequently than one large satellite. A median(mean) revisit time of 2.8(7.2) hrs.

  11. Helmet Mounted Eye Tracking for Virtual Panoramic Display Systems. Volume 2: Eye Tracker Specification and Design Approach

    Science.gov (United States)

    1989-08-01

    tracking will be used for eye controlled switch selection, cueing, eye-slaved aiming, and pilot state monitoring. Current eye tracking technology is...panoramic display (VPD). Eye tracker measurements will be used with prototype systems to assist in candidate display evaluation. Operationally, eye

  12. A new digital land mobile satellite system

    Science.gov (United States)

    Schneider, Philip

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

  13. China's Meteorological Satellite Application System

    Institute of Scientific and Technical Information of China (English)

    Zhang Jiashen

    2008-01-01

    @@ (Continued) Applications In Global Environment And Natural Disaster Monitoring 1) Application in world crop yield estimation China is now one of the few nations in the world that can provide operational service with both GEO and polar-orbit meteorological satellites.

  14. Alignments between galaxies, satellite systems and haloes

    CERN Document Server

    Shao, Shi; Frenk, Carlos S; Gao, Liang; Crain, Robert A; Schaller, Matthieu; Schaye, Joop; Theuns, Tom

    2016-01-01

    The spatial distribution of the satellite populations of the Milky Way and Andromeda are puzzling in that they are nearly perpendicular to the disks of their central galaxies. To understand the origin of such configurations we study the alignment of the central galaxy, satellite system and dark matter halo in the largest of the "Evolution and Assembly of GaLaxies and their Environments" (EAGLE) simulation. We find that centrals and their satellite systems tend to be well aligned with their haloes, with a median misalignment angle of $33^{\\circ}$ in both cases. While the centrals are better aligned with the inner $10$ kpc halo, the satellite systems are better aligned with the entire halo indicating that satellites preferentially trace the outer halo. The central - satellite alignment is weak (median misalignment angle of $52^{\\circ}$) and we find that around $20\\%$ of systems have a misalignment angle larger than $78^{\\circ}$, which is the value for the Milky Way. The central - satellite alignment is a conseq...

  15. Satellite power system (SPS) initial insurance evaluation

    Energy Technology Data Exchange (ETDEWEB)

    None

    1980-09-01

    The beginning of a process to educate the insurance industry about the Satellite Power System is reported. The report is divided into three sections. In the first section a general history describes how space risks are being insured today. This is followed by an attempt to identify the major risks inherent to the SPS. The final section presents a general projection of insurance market reactions to the Satellite Power System.

  16. Satellite Application for Disaster Management Information Systems

    Science.gov (United States)

    Okpanachi, George

    Abstract Satellites are becoming increasingly vital to modern day disaster management activities. Earth observation (EO) satellites provide images at various wavelengths that assist rapid-mapping in all phases of the disaster management cycle: mitigation of potential risks in a given area, preparedness for eventual disasters, immediate response to a disaster event, and the recovery/reconstruction efforts follo wing it. Global navigation satellite systems (GNSS) such as the Global Positioning System (GPS) assist all the phases by providing precise location and navigation data, helping manage land and infrastructures, and aiding rescue crews coordinate their search efforts. Effective disaster management is a complex problem, because it involves many parameters, which are usually not easy to measure and even identify: Analysis of current situation, planning, optimum resource management, coordination, controlling and monitoring current activities and making quick and correct decisions are only some of these parameters, whose complete list is very long. Disaster management information systems (DMIS) assist disaster management to analyse the situation better, make decisions and suggest further actions following the emergency plans. This requires not only fast and thorough processing and optimization abilities, but also real-time data provided to the DMIS. The need of DMIS for disaster’s real-time data can be satisfied by small satellites data utilization. Small satellites can provide up-to-data, plus a better media to transfer data. This paper suggests a rationale and a framework for utilization of small Satellite data by DMIS. DMIS should be used ‘’before’’, ‘’during’’ and ‘’after’’ the disasters. Data provided by the Small Satellites are almost crucial in any period of the disasters, because early warning can save lives, and satellite data may help to identify disasters before they occur. The paper also presents’ ‘when’’,

  17. Odyssey, an optimized personal communications satellite system

    Science.gov (United States)

    Rusch, Roger J.

    Personal communications places severe demands on service providers and transmission facilities. Customers are not satisfied with the current levels of service and want improvements. Among the characteristics that users seek are: lower service rates, hand held convenience, acceptable time delays, ubiquitous service, high availability, reliability, and high quality. The space industry is developing commercial space systems for providing mobile communications to personal telephones. Provision of land mobile satellite service is fundamentally different from the fixed satellite service provided by geostationary satellites. In fixed service, the earth based antennas can depend on a clear path from user to satellite. Mobile users in a terrestrial environment commonly encounter blockage due to vegetation, terrain or buildings. Consequently, high elevation angles are of premium value. TRW studied the issues and concluded that a Medium Earth Orbit constellation is the best solution for Personal Communications Satellite Service. TRW has developed Odyssey, which uses twelve satellites in medium altitude orbit to provide personal communications satellite service. The Odyssey communications system projects a multibeam antenna pattern to the Earth. The attitude control system orients the satellites to ensure constant coverage of land mass and coastal areas. Pointing can be reprogrammed by ground control to ensure optimized coverage of the desired service areas. The payload architecture features non-processing, "bent pipe" transponders and matrix amplifiers to ensure dynamic power delivery to high demand areas. Circuit capacity is 3000 circuits per satellite. Each satellite weighs 1917 kg (4226 pounds) at launch and the solar arrays provide 3126 Watts of power. Satellites are launched in pairs on Ariane, Atlas, or other vehicles. Each satellite is placed in a circular orbit at an altitude of 10,354 km. There are three orbit planes inclined at 55° to the equatorial plane

  18. A Space Based Solar Power Satellite System

    Science.gov (United States)

    Engel, J. M.; Polling, D.; Ustamujic, F.; Yaldiz, R.; et al.

    2002-01-01

    (SPoTS) supplying other satellites with energy. SPoTS is due to be commercially viable and operative in 2020. of Technology designed the SPoTS during a full-time design period of six weeks as a third year final project. The team, organized according to the principles of systems engineering, first conducted a literature study on space wireless energy transfer to select the most suitable candidates for use on the SPoTS. After that, several different system concepts have been generated and evaluated, the most promising concept being worked out in greater detail. km altitude. Each SPoTS satellite has a 50m diameter inflatable solar collector that focuses all received sunlight. Then, the received sunlight is further redirected by means of four pointing mirrors toward four individual customer satellites. A market-analysis study showed, that providing power to geo-stationary communication satellites during their eclipse would be most beneficial. At arrival at geo-stationary orbit, the focused beam has expended to such an extent that its density equals one solar flux. This means that customer satellites can continue to use their regular solar arrays during their eclipse for power generation, resulting in a satellite battery mass reduction. the customer satellites in geo-stationary orbit, the transmitted energy beams needs to be pointed with very high accuracy. Computations showed that for this degree of accuracy, sensors are needed, which are not mainstream nowadays. Therefore further research must be conducted in this area in order to make these high-accuracy-pointing systems commercially attractive for use on the SPoTS satellites around 2020. Total 20-year system lifetime cost for 18 SPoT satellites are estimated at approximately USD 6 billion [FY2001]. In order to compete with traditional battery-based satellite power systems or possible ground based wireless power transfer systems the price per kWh for the customer must be significantly lower than the present one

  19. Radiometric and geometric assessment of data from the RapidEye constellation of satellites

    Science.gov (United States)

    Chander, Gyanesh; Haque, Md. Obaidul; Sampath, Aparajithan; Brunn, A.; Trosset, G.; Hoffmann, D.; Roloff, S.; Thiele, M.; Anderson, C.

    2013-01-01

    To monitor land surface processes over a wide range of temporal and spatial scales, it is critical to have coordinated observations of the Earth's surface using imagery acquired from multiple spaceborne imaging sensors. The RapidEye (RE) satellite constellation acquires high-resolution satellite images covering the entire globe within a very short period of time by sensors identical in construction and cross-calibrated to each other. To evaluate the RE high-resolution Multi-spectral Imager (MSI) sensor capabilities, a cross-comparison between the RE constellation of sensors was performed first using image statistics based on large common areas observed over pseudo-invariant calibration sites (PICS) by the sensors and, second, by comparing the on-orbit radiometric calibration temporal trending over a large number of calibration sites. For any spectral band, the individual responses measured by the five satellites of the RE constellation were found to differ Geometric assessment was also performed to study the positional accuracy and relative band-to-band (B2B) alignment of the image data sets. The position accuracy was assessed by comparing the RE imagery against high-resolution aerial imagery, while the B2B characterization was performed by registering each band against every other band to ensure that the proper band alignment is provided for an image product. The B2B results indicate that the internal alignments of these five RE bands are in agreement, with bands typically registered to within 0.25 pixels of each other or better.

  20. Analyzing Head and Eye Movement System with CORBA

    Directory of Open Access Journals (Sweden)

    Wang Changyuan

    2013-11-01

    Full Text Available In order to study the vestibular system in different organs of movement as well as their collaboration between working mechanism, this paper designs a model of the common object request broker architecture (CORBA for the head and eye movement system based on the vestibular function. By analyzing physiological characteristics of the head and eye movement model, and further introducing the structure features of CORBA. It focus on the component composition and the model design of CORBA components library. According to the physiology work model of head and eye movement, the CORBA model of head and eye movement is established. As well as the structure of the model is designed in real application of head and eye movement measurement system. This paper provides a new way to research the head and eye movement system through using mathematical modeling and application structure which is based on vestibular function.    

  1. Verifying command sequences for satellite systems

    Science.gov (United States)

    Peters, James F., III; Ramanna, Sheela

    1992-10-01

    We present a formal basis for the design of a Checker used in validating safe schedules and in selecting error recovery schedules for satellite control systems. This design includes a high-level specification of Checker behavior and properties (called flight rules) of safe schedules. Specifications are written in Timed Linear Logic (TLL). Validation of schedules is performed in terms of real-time telemetry and deduction system proof rules. Telemetry (state information for satellite subsystems) serves as input to the Checker. Detection of violation of a flight rule by the Checker results in the selection of a contingency plan (error recovery schedule). The Checker is illustrated in terms of the TOPEX/Poseidon Oceanographic Satellite System.

  2. A relativistic and autonomous navigation satellite system

    CERN Document Server

    Delva, Pacôme; Kostić, Uros; Carloni, Sante

    2011-01-01

    A relativistic positioning system has been proposed by Bartolom\\'e Coll in 2002. Since then, several group developed this topic with different approaches. I will present a work done in collaboration with Ljubljana University and the ESA Advanced Concepts Team. We developed a concept, Autonomous Basis of Coordinates, in order to take advantage of the full autonomy of a satellite constellation for navigation and positioning, by means of satellite inter-links. I will present the advantages of this new paradigm and a number of potential application for reference systems, geophysics and relativistic gravitation.

  3. Advantages of Hybrid Global Navigation Satellite Systems

    Directory of Open Access Journals (Sweden)

    Asim Bilajbegović

    2007-05-01

    Full Text Available In a decision-making situation, what kind of GPS equipment to purchase, one always has a dilemma, tobuy hybrid (GPS+GLONASS or only GPS receivers? In the case of completeness of the GLONASS satellite system, this dilemma probably would not have existed. The answer to this dilemma is given in the present paper, but for the constellation of the GLONASS satellites in summer 2006 (14 satellites operational. Due to the short operational period of these satellites (for example GLONASS-M, 5 years, and not launching new ones, at this moment (February 25, 2007, only 10 satellites are operational. For the sake of research and giving answers to these questions, about 252 RTK measurements have been done using (GPS and GNSS receivers, on points with different obstructions of horizon. Besides that, initialisation time has been investigated for both systems from about 480 measurements, using rover's antenna with metal cover, during a time interval of 0.5, 2 and 5 seconds. Moreover, accuracy, firmware declared accuracy and redundancy of GPS and GNSS RTK measurements have been investigating.  

  4. Eye Vision Testing System and Eyewear Using Micromachines

    Directory of Open Access Journals (Sweden)

    Nabeel A. Riza

    2015-11-01

    Full Text Available Proposed is a novel eye vision testing system based on micromachines that uses micro-optic, micromechanic, and microelectronic technologies. The micromachines include a programmable micro-optic lens and aperture control devices, pico-projectors, Radio Frequency (RF, optical wireless communication and control links, and energy harvesting and storage devices with remote wireless energy transfer capabilities. The portable lightweight system can measure eye refractive powers, optimize light conditions for the eye under testing, conduct color-blindness tests, and implement eye strain relief and eye muscle exercises via time sequenced imaging. A basic eye vision test system is built in the laboratory for near-sighted (myopic vision spherical lens refractive error correction. Refractive error corrections from zero up to −5.0 Diopters and −2.0 Diopters are experimentally demonstrated using the Electronic-Lens (E-Lens and aperture control methods, respectively. The proposed portable eye vision test system is suited for children’s eye tests and developing world eye centers where technical expertise may be limited. Design of a novel low-cost human vision corrective eyewear is also presented based on the proposed aperture control concept. Given its simplistic and economical design, significant impact can be created for humans with vision problems in the under-developed world.

  5. Markerless monocular tracking system for guided external eye surgery.

    Science.gov (United States)

    Monserrat, C; Rupérez, M J; Alcañiz, M; Mataix, J

    2014-12-01

    This paper presents a novel markerless monocular tracking system aimed at guiding ophthalmologists during external eye surgery. This new tracking system performs a very accurate tracking of the eye by detecting invariant points using only textures that are present in the sclera, i.e., without using traditional features like the pupil and/or cornea reflections, which remain partially or totally occluded in most surgeries. Two known algorithms that compute invariant points and correspondences between pairs of images were implemented in our system: Scalable Invariant Feature Transforms (SIFT) and Speed Up Robust Features (SURF). The results of experiments performed on phantom eyes show that, with either algorithm, the developed system tracks a sphere at a 360° rotation angle with an error that is lower than 0.5%. Some experiments have also been carried out on images of real eyes showing promising behavior of the system in the presence of blood or surgical instruments during real eye surgery.

  6. A native IP satellite communications system

    Science.gov (United States)

    Koudelka, O.; Schmidt, M.; Ebert, J.; Schlemmer, H.; Kastner-Puschl, S.; Riedler, W.

    2004-08-01

    ≪ In the framework of ESA's ARTES-5 program the Institute of Applied Systems Technology (Joanneum Research) in cooperation with the Department of Communications and Wave Propagation has developed a novel meshed satellite communications system which is optimised for Internet traffic and applications (L*IP—Local Network Interconnection via Satellite Systems Using the IP Protocol Suite). Both symmetrical and asymmetrical connections are supported. Bandwidth on demand and guaranteed quality of service are key features of the system. A novel multi-frequency TDMA access scheme utilises efficient methods of IP encapsulation. In contrast to other solutions it avoids legacy transport network techniques. While the DVB-RCS standard is based on ATM or MPEG transport cells, the solution of the L*IP system uses variable-length cells which reduces the overhead significantly. A flexible and programmable platform based on Linux machines was chosen to allow the easy implementation and adaptation to different standards. This offers the possibility to apply the system not only to satellite communications, but provides seamless integration with terrestrial fixed broadcast wireless access systems. The platform is also an ideal test-bed for a variety of interactive broadband communications systems. The paper describes the system architecture and the key features of the system.

  7. Eye movement-invariant representations in the human visual system.

    Science.gov (United States)

    Nishimoto, Shinji; Huth, Alexander G; Bilenko, Natalia Y; Gallant, Jack L

    2017-01-01

    During natural vision, humans make frequent eye movements but perceive a stable visual world. It is therefore likely that the human visual system contains representations of the visual world that are invariant to eye movements. Here we present an experiment designed to identify visual areas that might contain eye-movement-invariant representations. We used functional MRI to record brain activity from four human subjects who watched natural movies. In one condition subjects were required to fixate steadily, and in the other they were allowed to freely make voluntary eye movements. The movies used in each condition were identical. We reasoned that the brain activity recorded in a visual area that is invariant to eye movement should be similar under fixation and free viewing conditions. In contrast, activity in a visual area that is sensitive to eye movement should differ between fixation and free viewing. We therefore measured the similarity of brain activity across repeated presentations of the same movie within the fixation condition, and separately between the fixation and free viewing conditions. The ratio of these measures was used to determine which brain areas are most likely to contain eye movement-invariant representations. We found that voxels located in early visual areas are strongly affected by eye movements, while voxels in ventral temporal areas are only weakly affected by eye movements. These results suggest that the ventral temporal visual areas contain a stable representation of the visual world that is invariant to eye movements made during natural vision.

  8. Neptunian Satellites observed with Keck AO system

    Science.gov (United States)

    Marchis, F.; Urata, R.; de Pater, I.; Gibbard, S.; Hammel, H. B.; Berthier, J.

    2004-05-01

    The Neptunian system was observed on 9 different nights between July 2002 and October 2003 with the 10-m Keck telescope on Mauna Kea, Hawaii, and its facility instrument NIRC2 coupled with the Adaptive Optics system. Data were recorded in J (1.2μ m), and H (2.2μ m) bands. The angular resolution achieved on a one-minute integration time image is 0.50 arcsec, corresponding to a spatial resolution of 1100 km. The images display small structures such as the rings (de Pater et al. 2004), clouds in the atmosphere (Gibbard et al. 2003), and inner satellites, mainly Proteus, Larissa, Galatea, Despina, and Thalassa. On the 40 images, the positions and intensities of the satellites detected were accurately measured fitting the signal with a gaussian profile. The center of Neptune was obtained by fitting the disk position with an ellipse. After correcting for the detector distortion, we compared the satellite positions with the predicted ones delivered by several ephemerides. We used the JPL (NEP016 + NEP022 + DE405) and two IMCCE ephemerides, an old version (VSOP87+Owen et al., 1991) and a more recent one (DE405+Le Guyader et al., 1993). All cases, we confirmed the presence of an apparent shift between the predicted and the observed positions. Table 1 (see http://astron.berkeley.edu/ fmarchis/Science/Neptune/Satellites/) summarizes the mean distance of the shift for satellites most frequently observed and the various ephemerides. In this presentation, we will report the positions of the satellites, and present their color and possible photometric variations derived from the observations. This work has been partially supported by the National Science Foundation Science and Technology Center for Adaptive Optics, managed by the University of California at Santa Cruz under cooperative agreement No. AST - 9876783.

  9. New eyes on the sun a guide to satellite images and amateur observation

    CERN Document Server

    Wilkinson, John

    2012-01-01

    Information collected by satellites recently sent by the USA, the European Space Agency, Japan, Germany, the United Kingdom, and Russia to monitor the Sun has changed our knowledge and understanding of the Sun, particularly its effect on Earth. This book presents these findings in a way that will be welcomed by amateur astronomers, students, educators and anyone interested in the Sun. Enhanced by many colour photographs, the book combines newly acquired scientific understanding with detailed descriptions of features visible on the Sun’s surface and in its atmosphere. In the past, observing the Sun has been left to academics with specialised instruments, since solar observation has been unsafe because of the risk of eye damage.  This book explains how amateur astronomers can safely observe the various solar phenomena using special hydrogen-alpha telescopes that are not too expensive. Amateurs can now make a positive contribution to science by monitoring the Sun as professionals do.  Amateurs can also acces...

  10. A Novel scoring system for distinguishing keratoconus from normal eyes.

    Science.gov (United States)

    Oruçoğlu, Faik; Toker, Ebru

    2016-10-01

    To evaluate the accuracy of a novel scoring system in differentiation of keratoconus (KC) eyes from normal eyes using a Scheimpflug camera system tomography. Marmara University Hospital, Istanbul, Turkey and Birinci Eye Hospital, Istanbul, Turkey. Retrospective case-control study. The study included 624 keratoconus eyes and 512 healthy eyes. Thirty nine significant parameters obtained from the Scheimpflug imaging system (Pentacam-Oculus Optikgeräte GmbH, Wetzlar, Germany) were studied. The cut-off value and area under receiver operating characteristic (AUROC) curve analysis for each studied parameter were established in the previous study. Minus three and plus three standard deviations of the cut-off value were scored after multiplication of AUROC for each parameter. The sum of all scores (TKS; Total Keratoconus Score) was compared between keratoconus and normal eyes. Average TKS value was -29.57±5.65 (Range from -43.11 to -7.09) in normal eyes and 36.23±24.3 (Range from -16.82 to 97.45) in keratoconus eyes (pkeratoconus group from the normal group with 99% sensitivity and 99% specificity at the best cut-off point of -12.45. The new scoring system measured by the Scheimpflug imaging system provides perfect discrimination of keratoconus from normal corneas. Copyright © 2016 British Contact Lens Association. Published by Elsevier Ltd. All rights reserved.

  11. Networks for Autonomous Formation Flying Satellite Systems

    Science.gov (United States)

    Knoblock, Eric J.; Konangi, Vijay K.; Wallett, Thomas M.; Bhasin, Kul B.

    2001-01-01

    The performance of three communications networks to support autonomous multi-spacecraft formation flying systems is presented. All systems are comprised of a ten-satellite formation arranged in a star topology, with one of the satellites designated as the central or "mother ship." All data is routed through the mother ship to the terrestrial network. The first system uses a TCP/lP over ATM protocol architecture within the formation the second system uses the IEEE 802.11 protocol architecture within the formation and the last system uses both of the previous architectures with a constellation of geosynchronous satellites serving as an intermediate point-of-contact between the formation and the terrestrial network. The simulations consist of file transfers using either the File Transfer Protocol (FTP) or the Simple Automatic File Exchange (SAFE) Protocol. The results compare the IF queuing delay, and IP processing delay at the mother ship as well as application-level round-trip time for both systems, In all cases, using IEEE 802.11 within the formation yields less delay. Also, the throughput exhibited by SAFE is better than FTP.

  12. Communications satellite system for Africa

    Science.gov (United States)

    Kriegl, W.; Laufenberg, W.

    1980-09-01

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

  13. THE FLY’S EYE CAMERA SYSTEM

    Directory of Open Access Journals (Sweden)

    László Mészáros

    2014-01-01

    Full Text Available Hacemos una introducci ́on del Fly’s Eye Camera System, un di spositivo de monitorizaci ́on de todo cielo con el prop ́osito de realizar astronom ́ıa de dominio temporal. Es te dise ̃no de sistema de c ́amaras proveer ́a conjuntos de datos complementarios a otros sondeos sin ́opticos como L SST o Pan-STARRS. El campo de visi ́on efectivo se obtiene con 19 c ́amaras dispuestas en un mosaico de forma e sf ́erica. Dichas c ́amaras del dispositivo se apoyan en una montura hexapodal que es completamente capaz d e hacer seguimiento sid ́ereo para exposiciones consecutivas. Esta plataforma tiene muchas ventajas. Prim ero, s ́olo requiere un componente m ́ovil y no incluye partes ́unicas. Por lo tanto este dise ̃no no s ́olo elimina lo s problemas causados por elementos ́unicos, sino que la redundancia del hex ́apodo permite una operaci ́on sin pro blemas incluso si una o dos de las piernas est ́an atoradas. Otra ventaja es que se puede calibrar a si mismo med iante estrellas observadas independientemente de su ubicaci ́on geogr ́afica como de la alineaci ́on polar de la m ontura. Todos los elementos mec ́anicos y electr ́onicos est ́an dise ̃nados dentro de nuestro instituto del Observat orio Konkoly. Actualmente, nuestro instrumento est ́a en fase de pruebas con un hex ́apodo operativo y un n ́umero red ucido de c ́amaras.

  14. Eye Tracking System for Enhanced Learning Experiences

    Science.gov (United States)

    Sungkur, R. K.; Antoaroo, M. A.; Beeharry, A.

    2016-01-01

    Nowadays, we are living in a world where information is readily available and being able to provide the learner with the best suited situations and environment for his/her learning experiences is of utmost importance. In most learning environments, information is basically available in the form of written text. According to the eye-tracking…

  15. Eye Tracking System for Enhanced Learning Experiences

    Science.gov (United States)

    Sungkur, R. K.; Antoaroo, M. A.; Beeharry, A.

    2016-01-01

    Nowadays, we are living in a world where information is readily available and being able to provide the learner with the best suited situations and environment for his/her learning experiences is of utmost importance. In most learning environments, information is basically available in the form of written text. According to the eye-tracking…

  16. Video Conference System that Keeps Mutual Eye Contact Among Participants

    Directory of Open Access Journals (Sweden)

    Masahiko Yahagi

    2011-10-01

    Full Text Available A novel video conference system is developed. Suppose that three people A, B, and C attend the video conference, the proposed system enables eye contact among every pair. Furthermore, when B and C chat, A feels as if B and C were facing each other (eye contact seems to be kept among B and C. In the case of a triangle video conference, the respective video system is composed of a half mirror, two video cameras, and two monitors. Each participant watches other participants' images that are reflected by the half mirror. Cameras are set behind the half mirror. Since participants' image (face and the camera position are adjusted to be the same direction, eye contact is kept and conversation becomes very natural compared with conventional video conference systems where participants' eyes do not point to the other participant. When 3 participants sit at the vertex of an equilateral triangle, eyes can be kept even for the situation mentioned above (eye contact between B and C from the aspect of A. Eye contact can be kept not only for 2 or 3 participants but also any number of participants as far as they sit at the vertex of a regular polygon.

  17. Optimal Control of the Compensatory Eye Movement System

    NARCIS (Netherlands)

    T.M. Sibindi (Tafadzwa)

    2015-01-01

    markdownabstractIn this thesis, we utilized behavioural, electrophysiological, computational and stimulation techniques to delve our knowledge further into the functional neural network of the compensatory eye movement system (CEM). We first investigated the superposition violations and non-lineari

  18. The eye in systemic disease | Lenake | South African Family Practice

    African Journals Online (AJOL)

    Abstract. The eye is a unique organ which is often involved in systemic disease. ... virus/acquired immune deficiency syndrome, syphilis, some dermatological conditions and the ocular side-effects of certain drugs, are discussed in this article.

  19. Analyzing Head and Eye Movement System with CORBA

    OpenAIRE

    Wang Changyuan; Zhang Jing; Chen YuLong

    2013-01-01

    In order to study the vestibular system in different organs of movement as well as their collaboration between working mechanism, this paper designs a model of the common object request broker architecture (CORBA) for the head and eye movement system based on the vestibular function. By analyzing physiological characteristics of the head and eye movement model, and further introducing the structure features of CORBA. It focus on the component composition and the model design of CORBA compon...

  20. Technology for a quasi-GSO satellite communications system

    OpenAIRE

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

    1999-01-01

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

  1. The NOAA Satellite Observing System Architecture Study

    Science.gov (United States)

    Volz, Stephen; Maier, Mark; Di Pietro, David

    2016-01-01

    NOAA is beginning a study, the NOAA Satellite Observing System Architecture (NSOSA) study, to plan for the future operational environmental satellite system that will follow GOES and JPSS, beginning about 2030. This is an opportunity to design a modern architecture with no pre-conceived notions regarding instruments, platforms, orbits, etc. The NSOSA study will develop and evaluate architecture alternatives to include partner and commercial alternatives that are likely to become available. The objectives will include both functional needs and strategic characteristics (e.g., flexibility, responsiveness, sustainability). Part of this study is the Space Platform Requirements Working Group (SPRWG), which is being commissioned by NESDIS. The SPRWG is charged to assess new or existing user needs and to provide relative priorities for observational needs in the context of the future architecture. SPRWG results will serve as input to the process for new foundational (Level 0 and Level 1) requirements for the next generation of NOAA satellites that follow the GOES-R, JPSS, DSCOVR, Jason-3, and COSMIC-2 missions.

  2. Incoherent correlator system for satellite orientation control

    Science.gov (United States)

    Kouris, Aristodemos; Young, Rupert C. D.; Chatwin, Christopher R.; Birch, Philip M.

    2002-03-01

    An incoherent correlator configuration is proposed and experimentally demonstrated that is capable of recognizing star patterns. The device may thus be employed for the orientation and navigation of a satellite or spacecraft. The correlator employs starlight directly and requires no laser or input spatial light modulator for operation. The filter is constructed form an array of mirrors that may be individually appropriately tilted so as recognize a particular star arrangement. The only other components of the system are a converging lens and CCD array detector. The device is capable of determining the pointing direction and rotation of a satellite or space vehicle. Experimental results employing the mirror array device illuminated with a point source early to simulate starlight are presented.

  3. System implementation for Earth Radiation Budget Satellite System

    Science.gov (United States)

    Cooper, J. E.; Woerner, C. V.

    1978-01-01

    A description is presented of the instrument system which is needed for the Earth Radiation Budget Satellite System (ERBSS). The system is to be composed of instruments on two of NOAA's near-polar sun-synchronous Tiros-N/NOAA A through G series of operational satellites and on a NASA midinclination satellite of the Applications Explorer Mission (AEM) type referred to as ERBS-A/AEM. The Tiros-N/NOAA satellites will be in nominal 833 km altitude circular orbits with orbital inclinations of 98 deg. The AEM satellite will be in a circular orbit with an inclination of approximately 56 deg and a nominal altitude of 600 km. Each satellite will carry wide field-of-view (WFOV) and medium field-of-view (MFOV) sensors, a sensor for measuring the solar constant, and a narrow field-of-view (NFOV) cross-track scanner. The conceptual design of the W/MFOV instrument is discussed along with the conceptual design of the scanner.

  4. High-Speed Noninvasive Eye-Tracking System

    Science.gov (United States)

    Talukder, Ashit; LaBaw, Clayton; Michael-Morookian, John; Monacos, Steve; Serviss, Orin

    2007-01-01

    The figure schematically depicts a system of electronic hardware and software that noninvasively tracks the direction of a person s gaze in real time. Like prior commercial noninvasive eye-tracking systems, this system is based on (1) illumination of an eye by a low-power infrared light-emitting diode (LED); (2) acquisition of video images of the pupil, iris, and cornea in the reflected infrared light; (3) digitization of the images; and (4) processing the digital image data to determine the direction of gaze from the centroids of the pupil and cornea in the images. Relative to the prior commercial systems, the present system operates at much higher speed and thereby offers enhanced capability for applications that involve human-computer interactions, including typing and computer command and control by handicapped individuals,and eye-based diagnosis of physiological disorders that affect gaze responses.

  5. Technical comparison of several global mobile satellite communications systems

    Science.gov (United States)

    Comparetto, Gary M.

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

  6. Optimal Release Control of Companion Satellite System Using Electromagnetic Forces

    Institute of Scientific and Technical Information of China (English)

    Zengwen Xu,Peng Shi; Yushan Zhao∗

    2015-01-01

    Electromagnetic forces generated by the inter⁃action of component satellites can be used to release companion satellites. Optimal release trajectories for companion satellite system using inter⁃electromagnetic forces were investigated. Firstly, nonlinear relative motion dynamic equations of a two⁃craft electromagnetic companion satellite system were derived in spatial polar coordinates. Then principles of electromagnetic satellite formation flying were introduced. Secondly, the characteristics of the electromagnetic companion satellites release were analyzed and optimal release trajectories of companion satellites using electromagnetic forces were obtained using Gauss pseudospectral method. Three performance criteria were chosen as minimum time, minimum acceleration of the separation distance and minimum control acceleration. Finally, three release examples including expansion along separation distance, rotation in orbital plane and stable formation reconfiguration were given to demonstrate the feasibility of this method. Results indicated that the release trajectories can converge to optimal solutions effectively and the concept of release companion satellites using electromagnetic forces is practicable.

  7. Do common systems control eye movements and motion extrapolation?

    Science.gov (United States)

    Makin, Alexis D J; Poliakoff, Ellen

    2011-07-01

    People are able to judge the current position of occluded moving objects. This operation is known as motion extrapolation. It has previously been suggested that motion extrapolation is independent of the oculomotor system. Here we revisited this question by measuring eye position while participants completed two types of motion extrapolation task. In one task, a moving visual target travelled rightwards, disappeared, then reappeared further along its trajectory. Participants discriminated correct reappearance times from incorrect (too early or too late) with a two-alternative forced-choice button press. In the second task, the target travelled rightwards behind a visible, rectangular occluder, and participants pressed a button at the time when they judged it should reappear. In both tasks, performance was significantly different under fixation as compared to free eye movement conditions. When eye movements were permitted, eye movements during occlusion were related to participants' judgements. Finally, even when participants were required to fixate, small changes in eye position around fixation (<2°) were influenced by occluded target motion. These results all indicate that overlapping systems control eye movements and judgements on motion extrapolation tasks. This has implications for understanding the mechanism underlying motion extrapolation.

  8. National Satellite Forest Monitoring systems for REDD+

    Science.gov (United States)

    Jonckheere, I. G.

    2012-12-01

    Reducing Emissions from Deforestation and Forest Degradation (REDD) is an effort to create a financial value for the carbon stored in forests, offering incentives for developing countries to reduce emissions from forested lands and invest in low-carbon paths to sustainable development. "REDD+" goes beyond deforestation and forest degradation, and includes the role of conservation, sustainable management of forests and enhancement of forest carbon stocks. In the framework of getting countries ready for REDD+, the UN-REDD Programme assists developing countries to prepare and implement national REDD+ strategies. For the monitoring, reporting and verification, FAO supports the countries to develop national satellite forest monitoring systems that allow for credible measurement, reporting and verification (MRV) of REDD+ activities. These are among the most critical elements for the successful implementation of any REDD+ mechanism. The UN-REDD Programme through a joint effort of FAO and Brazil's National Space Agency, INPE, is supporting countries to develop cost- effective, robust and compatible national monitoring and MRV systems, providing tools, methodologies, training and knowledge sharing that help countries to strengthen their technical and institutional capacity for effective MRV systems. To develop strong nationally-owned forest monitoring systems, technical and institutional capacity building is key. The UN-REDD Programme, through FAO, has taken on intensive training together with INPE, and has provided technical help and assistance for in-country training and implementation for national satellite forest monitoring. The goal of the support to UN-REDD pilot countries in this capacity building effort is the training of technical forest people and IT persons from interested REDD+ countries, and to set- up the national satellite forest monitoring systems. The Brazilian forest monitoring system, TerraAmazon, which is used as a basis for this initiative, allows

  9. Joint Polar Satellite System Common Ground System Overview

    Science.gov (United States)

    Jamilkowski, M. L.; Miller, S. W.; Grant, K. D.

    2012-12-01

    The National Oceanic and Atmospheric Administration (NOAA) and National Aeronautics and Space Administration (NASA) are jointly acquiring the next-generation civilian weather and environmental satellite system: the Joint Polar Satellite System (JPSS). JPSS will contribute the afternoon orbit component and ground processing system of the restructured National Polar-orbiting Operational Environmental Satellite System (NPOESS). As such, JPSS replaces the current Polar-orbiting Operational Environmental Satellites (POES) managed by NOAA and the ground processing component of both Polar-orbiting Operational Environmental Satellites and the Defense Meteorological Satellite Program (DMSP) replacement, previously known as the Defense Weather Satellite System (DWSS), managed by the Department of Defense (DoD). The JPSS satellites will carry a suite of sensors designed to collect meteorological, oceanographic, climatological, and solar-geophysical observations of the earth, atmosphere, and space. The ground processing system for JPSS is known as the JPSS Common Ground System (JPSS CGS), and consists of a Command, Control, and Communications Segment (C3S) and an Interface Data Processing Segment (IDPS). Both segments are developed by Raytheon Intelligence and Information Systems (IIS). The C3S currently flies the Suomi National Polar Partnership (Suomi NPP) satellite and transfers mission data from Suomi NPP and between the ground facilities. The IDPS processes Suomi NPP satellite data to provide Environmental Data Records (EDRs) to NOAA and DoD processing centers operated by the United States government. When the JPSS-1 satellite is launched in early 2017, the responsibilities of the C3S and the IDPS will be expanded to support both Suomi NPP and JPSS-1. The JPSS CGS currently provides data processing for Suomi NPP, generating multiple terabytes per day across over two dozen environmental data products; that workload will be multiplied by two when the JPSS-1 satellite is

  10. Mental Fatigue Monitoring Using a Wearable Transparent Eye Detection System

    Directory of Open Access Journals (Sweden)

    Kota Sampei

    2016-01-01

    Full Text Available We propose mental fatigue measurement using a wearable eye detection system. The system is capable of acquiring movement of the pupil and blinking from the light reflected from the eye. The reflection is detected by dye-sensitized photovoltaic cells. Since these cells are patterned onto the eyeglass and do not require external input power, the system is notable for its lightweight and low power consumption and can be combined with other wearable devices, such as a head mounted display. We performed experiments to correlate information obtained by the eye detection system with the mental fatigue of the user. Since it is quite difficult to evaluate mental fatigue objectively and quantitatively, we assumed that the National Aeronautics and Space Administration Task Load Index (NASA-TLX had a strong correlation with te mental fatigue. While a subject was requested to conduct calculation tasks, the eye detection system collected his/her information that included position, velocity and total movement of the eye, and amount and frequency of blinking. Multiple regression analyses revealed the correlation between NASA-TLX and the information obtained for 3 out of 5 subjects.

  11. System architecture for the Canadian interim mobile satellite system

    Science.gov (United States)

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

    1988-05-01

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

  12. Satellite power system (SPS) public outreach experiment

    Energy Technology Data Exchange (ETDEWEB)

    McNeal, S.R.

    1980-12-01

    To improve the results of the Satellite Power System (SPS) Concept Development and Evaluation Program, an outreach experiment was conducted. Three public interest groups participated: the L-5 Society (L-5), Citizen's Energy Project (CEP), and the Forum for the Advancement of Students in Science and Technology (FASST). Each group disseminated summary information about SPS to approximately 3000 constituents with a request for feedback on the SPS concept. The objectives of the outreach were to (1) determine the areas of major concern relative to the SPS concept, and (2) gain experience with an outreach process for use in future public involvement. Due to the combined efforts of all three groups, 9200 individuals/organizations received information about the SPS concept. Over 1500 receipients of this information provided feedback. The response to the outreach effort was positive for all three groups, suggesting that the effort extended by the SPS Project Division to encourage an information exchange with the public was well received. The general response to the SPS differed with each group. The L-5 position is very much in favor of SPS; CEP is very much opposed and FASST is relatively neutral. The responses are analyzed, and from the responses some questions and answers about the satellite power system are presented in the appendix. (WHK)

  13. EyeScreen: A Vision-Based Gesture Interaction System

    Institute of Scientific and Technical Information of China (English)

    LI Shan-qing; XU Yi-hua; JIA Yun-de

    2007-01-01

    EyeScreen is a vision-based interaction system which provides a natural gesture interface for human-computer interaction (HCI) by tracking human fingers and recognizing gestures. Multi-view video images are captured by two cameras facing a computer screen, which can be used to detect clicking actions of a fingertip and improve the recognition rate. The system enables users to directly interact with rendered objects on the screen. Robustness of the system has been verified by extensive experiments with different user scenarios. EyeScreen can be used in many applications such as intelligent interaction and digital entertainment.

  14. SAW based systems for mobile communications satellites

    Science.gov (United States)

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

    1993-01-01

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

  15. Global Ocean Surveillance With Electronic Intelligence Based Satellite System

    Science.gov (United States)

    Venkatramanan, Haritha

    2016-07-01

    The objective of this proposal is to design our own ELINT based satellite system to detect and locate the target by using satellite Trilateration Principle. The target position can be found by measuring the radio signals arrived at three satellites using Time Difference of Arrival(TDOA) technique. To locate a target it is necessary to determine the satellite position. The satellite motion and its position is obtained by using Simplified General Perturbation Model(SGP4) in MATLAB. This SGP4 accepts satellite Two Line Element(TLE) data and returns the position in the form of state vectors. These state vectors are then converted into observable parameters and then propagated in space. This calculations can be done for satellite constellation and non - visibility periods can be calculated. Satellite Trilateration consists of three satellites flying in formation with each other. The satellite constellation design consists of three satellites with an inclination of 61.3° maintained at equal distances between each other. The design is performed using MATLAB and simulated to obtain the necessary results. The target's position can be obtained using the three satellites ECEF Coordinate system and its position and velocity can be calculated in terms of Latitude and Longitude. The target's motion is simulated to obtain the Speed and Direction of Travel.

  16. Communication satellite system beyond the year 2000

    Science.gov (United States)

    Robertson, G. J.; Fourquet, J. M.

    1991-10-01

    The primary evolutionary factors of satellite communications technologies are reviewed based on the results of a study of novel satellite developments. A critical evaluation of the viability and availability of the technologies is utilized in conjunction with market forecasts to determine promising commercial strategies. Modern technologies are almost prepared for the development of a class of communications satellites and include bandwidth utilization, spacecraft bus modularity, and functional integration.

  17. Use of satellite images for the monitoring of water systems

    Science.gov (United States)

    Hillebrand, Gudrun; Winterscheid, Axel; Baschek, Björn; Wolf, Thomas

    2015-04-01

    Satellite images are a proven source of information for monitoring ecological indicators in coastal waters and inland river systems. This potential of remote sensing products was demonstrated by recent research projects (e.g. EU-funded project Freshmon - www.freshmon.eu) and other activities by national institutions. Among indicators for water quality, a particular focus was set on the temporal and spatial dynamics of suspended particulate matter (SPM) and Chlorophyll-a (Chl-a). The German Federal Institute of Hydrology (BfG) was using the Weser and Elbe estuaries as test cases to compare in-situ measurements with results obtained from a temporal series of automatically generated maps of SPM distributions based on remote sensing data. Maps of SPM and Chl-a distributions in European inland rivers and alpine lakes were generated by the Freshmon Project. Earth observation based products are a valuable source for additional data that can well supplement in-situ monitoring. For 2015, the BfG and the Institute for Lake Research of the State Institute for the Environment, Measurements and Nature Conservation of Baden-Wuerttemberg, Germany (LUBW) are in the process to start implementing an operational service for monitoring SPM and Chl-a based on satellite images (Landsat 7 & 8, Sentinel 2, and if required other systems with higher spatial resolution, e.g. Rapid Eye). In this 2-years project, which is part of the European Copernicus Programme, the operational service will be set up for - the inland rivers of Rhine and Elbe - the North Sea estuaries of Elbe, Weser and Ems. Furthermore - Lake Constance and other lakes located within the Federal State of Baden-Wuerttemberg. In future, the service can be implemented for other rivers and lakes as well. Key feature of the project is a data base that holds the stock of geo-referenced maps of SPM and Chl-a distributions. Via web-based portals (e.g. GGInA - geo-portal of the BfG; UIS - environmental information system of the

  18. Simultaneous single epoch satellite clock modelling in Global Navigation Satellite Systems

    Science.gov (United States)

    Thongtan, Thayathip

    In order to obtain high quality positions from navigation satellites, range errors have to be identified and either modelled or estimated. This thesis focuses on satellite clock errors, which are needed to be known because satellite clocks are not perfectly synchronised with navigation system time. A new approach, invented at UCL, for the simultaneous estimation, in a single epoch, of all satellite clock offsets within a Global Navigation Satellite System (GNSS) from range data collected at a large number of globally distributed ground stations is presented. The method was originally tested using only data from a limited number of GPS satellites and ground stations. In this work a total of 50 globally distributed stations and the whole GPS constellation are used in order to investigate more fully the capabilities of the method, in terms of both accuracy and reliability. A number of different estimation models have been tested. These include those with different weighting schemes, those with and without tropospheric bias parameters and those that include assumptions regarding prior knowledge of satellite orbits. In all cases conclusions have been drawn based on formal error propagation theory. Accuracy has been assessed largely through the sizes of the predicted satellite clock standard deviations and, in the case of simultaneously estimating satellite positions, their error ellipsoids. Both internal and external reliability have been assessed as these are important contributors to integrity, something that is essential for many practical applications. It has been found that the accuracy and reliability of satellite clock offsets are functions of the number of known ground station clocks and distance from them, quality of orbits and quality of range measurement. Also the introduction of tropospheric zenith delay parameters into the model reduces both accuracy and reliability by amounts depending on satellite elevation angles. (Abstract shortened by UMI.)

  19. Automatic surveillance system using fish-eye lens camera

    Institute of Scientific and Technical Information of China (English)

    Xue Yuan; Yongduan Song; Xueye Wei

    2011-01-01

    This letter presents an automatic surveillance system using fish-eye lens camera. Our system achieves wide-area automatic surveillance without a dead angle using only one camera. We propose a new human detection method to select the most adaptive classifier based on the locations of the human candidates.Human regions are detected from the fish-eye image effectively and are corrected for perspective versions.An experiment is performed on indoor video sequences with different illumination and crowded conditions,with results demonstrating the efficiency of our algorithm.%@@ This letter presents an automatic surveillance system using fish-eye lens camera. Our system achieves wide-area automatic surveillance without a dead angle using only one camera. We propose a new human detection method to select the most adaptive classifier based on the locations of the human candidates. Human regions are detected from the fish-eye image effectively and are corrected for perspective versions. An experiment is performed on indoor video sequences with different illumination and crowded conditions, with results demonstrating the efficiency of our algorithm.

  20. Global navigation satellite system; Jisedai kokoho senjo system

    Energy Technology Data Exchange (ETDEWEB)

    Kawano, S.; Suga, S. [Toshiba Corp., Tokyo (Japan)

    2000-05-01

    The safety of civil aviation relies on ground navigation aids. In areas where there are no ground aids and on oceanic air routes, aircraft must depend on their own navigation system. The predicted increase in civil aviation traffic in the near future will make it difficult for current navigation aids to support navigation in all phases of flights. To avoid this problem, the International Civil Aviation Organization (ICAO) is directing the establishment of standards for the global navigation satellite system (GNSS). GNSS employs navigation satellites, such as those of the global positioning system (GPS), to provide navigation capability throughout the world. In Japan, the Electronic Navigation Research Institute, the Ministry of Transport, and the Japan civil Aviation Promotion Foundation are carrying out research on this navigation system. Toshiba has been providing experimental equipment for this research. (author)

  1. Satellite data assimilation in global forecast system in India

    Science.gov (United States)

    Basu, Swati

    2014-11-01

    Satellite data is very important for model initialization and verification. A large number of satellite observations are currently assimilated into the Numerical Weather Prediction (NWP) systems at the National Centre for Medium Range Weather Forecasting (NCMRWF). Apart from Global meteorological observations from GTS, near-real time satellite observations are received at NCMRWF from other operational centres like ISRO, NOAA/NESDIS, EUMETCAST, etc. Recently India has become member of Asia-Pacific Regional ATOVS Retransmission Service (APRARS) for faster access to high resolution global satellite data useful for high resolution regional models. Indian HRPT at Chennai covers the APRARS data gap region over South East Asia. A robust data monitoring system has been implemented at NCMRWF to assess the quantity and quality of the data as well as the satellite sensor strength, before getting assimilated in the models. Validation of new satellite observations, especially from Indian satellites are being carried out against insitu observations and similar space borne platforms. After establishing the quality of the data, Observation System Experiments (OSEs) are being conducted to study their impact in the assimilation and forecast systems. OSEs have been carried out with the Oceansat-2 scatterometer winds and radiance data from Megha-Tropiques SAPHIR sensor. Daily rainfall analysis dataset is being generated by merging satellite estimates and in-situ observations. ASCAT soil wetness measurements from METOP satellite is being assimilated into the global model. Land surface parameters (LuLc and albedo) retrieved from Indian satellites are being explored for its possible usage in the global and regional models. OLR from Indian satellites are used for validating model outputs. This paper reviews the efforts made at NCMRWF in (i) assimilating the data from Indian/International satellites and (ii) generating useful products from the satellite data.

  2. GNSS global navigation satellite systems : GPS, GLONASS, Galileo, and more

    CERN Document Server

    Hofmann-Wellenhof, Bernhard; Wasle, Elmar

    2008-01-01

    This book is an extension to the acclaimed scientific bestseller "GPS - Theory and Practice". It covers Global Navigation Satellite Systems (GNSS) and includes the Russian GLONASS, the European system Galileo, and additional systems.

  3. Computer-Aided Communication Satellite System Analysis and Optimization.

    Science.gov (United States)

    Stagl, Thomas W.; And Others

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

  4. An Instructional Satellite System for the United States: Preliminary Considerations.

    Science.gov (United States)

    DuMolin, James R.; Morgan, Robert P.

    Based on educational, social, political, and other considerations, an instructional satellite system, AVSIN (Ausio-Visual Satellite Instruction), is hypothesized which represents one possible organizational and administrative arrangement for delivering large amounts of quality software to schools and learning centers. The AVSIN system is conceived…

  5. Power Processing Unit For Micro Satellite Electric Propulsion System

    Directory of Open Access Journals (Sweden)

    Savvas Spiridon

    2017-01-01

    Full Text Available The Micro Satellite Electric Propulsion System (MEPS program has been originated by the increasing need to provide a low-cost and low-power Electric Propulsion System (EPS for small satellites ( 92%, small size and weight and high reliability. Its functional modules and preliminary results obtained at breadboard level are also presented.

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

    Science.gov (United States)

    Smith, Partrick O.; Geraniotis, Evaggelos A.

    1988-01-01

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

  7. System refinement for content based satellite image retrieval

    Directory of Open Access Journals (Sweden)

    NourElDin Laban

    2012-06-01

    Full Text Available We are witnessing a large increase in satellite generated data especially in the form of images. Hence intelligent processing of the huge amount of data received by dozens of earth observing satellites, with specific satellite image oriented approaches, presents itself as a pressing need. Content based satellite image retrieval (CBSIR approaches have mainly been driven so far by approaches dealing with traditional images. In this paper we introduce a novel approach that refines image retrieval process using the unique properties to satellite images. Our approach uses a Query by polygon (QBP paradigm for the content of interest instead of using the more conventional rectangular query by image approach. First, we extract features from the satellite images using multiple tiling sizes. Accordingly the system uses these multilevel features within a multilevel retrieval system that refines the retrieval process. Our multilevel refinement approach has been experimentally validated against the conventional one yielding enhanced precision and recall rates.

  8. Development of environmental monitoring satellite systems in China

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    With the increase in global environmental problems,the necessity and urgency of remote sensing technology being applied to environmental monitoring has been widely recognized around the world.China has launched the environment and disaster monitoring and forecasting small satellite constellation HJ-1A/B and the FY3 atmosphere and environmental satellite,but they still cannot fully satisfy requirements for environmental monitoring.This paper summarizes the current status of satellite environmental monitoring in China and the existing problems of inadequate load design and low data utilization efficiency,and discusses the demand for environmental monitoring satellites.Based on the development of foreign satellite systems for environmental monitoring,the future development and key tasks of the environmental monitoring satellite system in China is discussed,as are some related initiatives.

  9. Network coding and its applications to satellite systems

    DEFF Research Database (Denmark)

    Vieira, Fausto; Roetter, Daniel Enrique Lucani

    2015-01-01

    Network coding has its roots in information theory where it was initially proposed as a way to improve a two-node communication using a (broadcasting) relay. For this theoretical construct, a satellite communications system was proposed as an illustrative example, where the relay node would...... be a satellite covering the two nodes. The benefits in terms of throughput, resilience, and flexibility of network coding are quite relevant for wireless networks in general, and for satellite systems in particular. This chapter presents some of the basics in network coding, as well as an overview of specific...... scenarios where network coding provides a significant improvement compared to existing solutions, for example, in broadcast and multicast satellite networks, hybrid satellite-terrestrial networks, and broadband multibeam satellites. The chapter also compares coding perspectives and revisits the layered...

  10. Network coding and its applications to satellite systems

    DEFF Research Database (Denmark)

    Vieira, Fausto; Roetter, Daniel Enrique Lucani

    2015-01-01

    Network coding has its roots in information theory where it was initially proposed as a way to improve a two-node communication using a (broadcasting) relay. For this theoretical construct, a satellite communications system was proposed as an illustrative example, where the relay node would...... be a satellite covering the two nodes. The benefits in terms of throughput, resilience, and flexibility of network coding are quite relevant for wireless networks in general, and for satellite systems in particular. This chapter presents some of the basics in network coding, as well as an overview of specific...... scenarios where network coding provides a significant improvement compared to existing solutions, for example, in broadcast and multicast satellite networks, hybrid satellite-terrestrial networks, and broadband multibeam satellites. The chapter also compares coding perspectives and revisits the layered...

  11. Reusable Reentry Satellite (RRS) system design study

    Science.gov (United States)

    1991-01-01

    The Reusable Reentry Satellite (RRS) is intended to provide investigators in several biological disciplines with a relatively inexpensive method to access space for up to 60 days with eventual recovery on Earth. The RRS will permit totally intact, relatively soft, recovery of the vehicle, system refurbishment, and reflight with new and varied payloads. The RRS is to be capable of three reflights per year over a 10-year program lifetime. The RRS vehicle will have a large and readily accessible volume near the vehicle center of gravity for the Payload Module (PM) containing the experiment hardware. The vehicle is configured to permit the experimenter late access to the PM prior to launch and rapid access following recovery. The RRS will operate in one of two modes: (1) as a free-flying spacecraft in orbit, and will be allowed to drift in attitude to provide an acceleration environment of less than 10(exp -5) g. the acceleration environment during orbital trim maneuvers will be less than 10(exp -3) g; and (2) as an artificial gravity system which spins at controlled rates to provide an artificial gravity of up to 1.5 Earth g. The RRS system will be designed to be rugged, easily maintained, and economically refurbishable for the next flight. Some systems may be designed to be replaced rather than refurbished, if cost effective and capable of meeting the specified turnaround time. The minimum time between recovery and reflight will be approximately 60 days. The PMs will be designed to be relatively autonomous, with experiments that require few commands and limited telemetry. Mass data storage will be accommodated in the PM. The hardware development and implementation phase is currently expected to start in 1991 with a first launch in late 1993.

  12. Space Solar Power Satellite Systems, Modern Small Satellites, and Space Rectenna

    Science.gov (United States)

    Bergsrud, Corey Alexis Marvin

    Space solar power satellite (SSPS) systems is the concept of placing large satellite into geostationary Earth orbit (GEO) to harvest and convert massive amounts of solar energy into microwave energy, and to transmit the microwaves to a rectifying antenna (rectenna) array on Earth. The rectenna array captures and converts the microwave power into usable power that is injected into the terrestrial electric grid for use. This work approached the microwave power beam as an additional source of power (with solar) for lower orbiting satellites. Assuming the concept of retrodirectivity, a GEO-SSPS antenna array system tracks and delivers microwave power to lower orbiting satellites. The lower orbiting satellites are equipped with a stacked photovoltaic (PV)/rectenna array hybrid power generation unit (HPGU) in order to harvest solar and/or microwave energy for on-board use during orbit. The area, and mass of the PV array part of the HPGU was reduced at about 32% beginning-of-life power in order to achieve the spacecraft power requirements. The HPGU proved to offer a mass decrease in the PGU, and an increase in mission life due to longer living component life of the rectenna array. Moreover, greater mission flexibility is achieved through a track and power delivery concept. To validate the potential advantages offered by a HPGU, a mission concept was presented that utilizes modern small satellites as technology demonstrators. During launch, a smaller power receiving "daughter" satellite sits inside a larger power transmitting "mother" satellite. Once separated from the launch vehicle the daughter satellite is ejected away from the mother satellite, and each satellite deploys its respective power transmitting or power receiving hardware's for experimentation. The concept of close proximity mission operations between the satellites is considered. To validate the technology of the space rectenna array part of the HPGU, six milestones were completed in the design. The first

  13. Study on fault locating technology for satellite power system

    Institute of Scientific and Technical Information of China (English)

    LONG Bing; JIANG Xing-wei; SONG Zheng-ji

    2005-01-01

    It is currently prevalent to locate faults for a satellite power system based on an expert system, not utilizing all the available information provided by tests. The casual network model for a satellite power system is presented. Considerations for failure probability of each component of the power system, the cost of applying each test, the influence of a precedent test result on the next test selection, and an optimal sequential testing algorithm for fault location is presented. This program is applied to locate the failure component of the power system of a satellite. The results show this program is very effective and it is very fast to generate an optimal diagnosis tree.

  14. The satellite based augmentation system – EGNOS for non-precision approach global navigation satellite system

    Directory of Open Access Journals (Sweden)

    Andrzej FELLNER

    2012-01-01

    Full Text Available First in the Poland tests of the EGNOS SIS (Signal in Space were conducted on 5th October 2007 on the flight inspection with SPAN (The Synchronized Position Attitude Navigation technology at the Mielec airfield. This was an introduction to a test campaign of the EGNOS-based satellite navigation system for air traffic. The advanced studies will be performed within the framework of the EGNOS-APV project in 2011. The implementation of the EGNOS system to APV-I precision approach operations, is conducted according to ICAO requirements in Annex 10. Definition of usefulness and certification of EGNOS as SBAS (Satellite Based Augmentation System in aviation requires thorough analyses of accuracy, integrity, continuity and availability of SIS. Also, the project will try to exploit the excellent accuracy performance of EGNOS to analyze the implementation of GLS (GNSS Landing System approaches (Cat I-like approached using SBAS, with a decision height of 200 ft. Location of the EGNOS monitoring station Rzeszów, located near Polish-Ukrainian border, being also at the east border of planned EGNOS coverage for ECAC states is very useful for SIS tests in this area. According to current EGNOS programmed schedule, the project activities will be carried out with EGNOS system v2.2, which is the version released for civil aviation certification. Therefore, the project will allow demonstrating the feasibility of the EGNOS certifiable version for civil applications.

  15. Optical Systems of Biopsy: The Invisible Eye

    Directory of Open Access Journals (Sweden)

    Kriti Bagri-Manjrekar

    2012-01-01

    Full Text Available The exploration of new methods and techniques for the diagnosis of malignant tumours has always attracted the attention of scientists. The development of adjunct tools to facilitate the non invasive screening of high risk lesions in real time has the potential to significantly improve our ability to reduce the dismal morbidity and mortality of oral cancer. Despite easy accessibility of the oral cavity to examination, there is no satisfactory method to adequately screen and detect precancers non-invasively. The current method of oral cancer diagnosis clinically relies heavily on visual examination of the oral cavity. However, discerning potentially malignant and early malignant lesions from common benign inflammatory conditions can be difficult at times. There is a need for an objective method that could provide real- time results and be routinely applied to a large population. Though science is yet to present such a perfect technique, Optical Biopsy Systems developed using knowledge of light and tissue interaction, can provide a plausible option.

  16. Grassland habitat mapping by intra-annual time series analysis - Comparison of RapidEye and TerraSAR-X satellite data

    Science.gov (United States)

    Schuster, Christian; Schmidt, Tobias; Conrad, Christopher; Kleinschmit, Birgit; Förster, Michael

    2015-02-01

    Remote sensing concepts are needed to monitor open landscape habitats for environmental change and biodiversity loss. However, existing operational approaches are limited to the monitoring of European dry heaths only. They need to be extended to further habitats. Thus far, reported studies lack the exploitation of intra-annual time series of high spatial resolution data to take advantage of the vegetations' phenological differences. In this study, we investigated the usefulness of such data to classify grassland habitats in a nature reserve area in northeastern Germany. Intra-annual time series of 21 observations were used, acquired by a multi-spectral (RapidEye) and a synthetic aperture radar (TerraSAR-X) satellite system, to differentiate seven grassland classes using a Support Vector Machine classifier. The classification accuracy was evaluated and compared with respect to the sensor type - multi-spectral or radar - and the number of acquisitions needed. Our results showed that very dense time series allowed for very high accuracy classifications (>90%) of small scale vegetation types. The classification for TerraSAR-X obtained similar accuracy as compared to RapidEye although distinctly more acquisitions were needed. This study introduces a new approach to enable the monitoring of small-scale grassland habitats and gives an estimate of the amount of data required for operational surveys.

  17. Becoming Bombs: 3D Animated Satellite Imagery and the Weaponization of the Civic Eye

    Directory of Open Access Journals (Sweden)

    Roger Stahl

    2010-02-01

    Full Text Available This essay traces the recent history of 3D satellite animation from its military origins to its visibility in the civic sphere. Specifically, technologies unveiled in 2004 as Google Earth first received widespread public visibility in the television coverage of the 2003 U.S. invasion of Iraq. The essay first maps the political economy of the “military-media-geotech” complex, focusing mainly on the coverage of the Iraq War as an nexus of interests. Second, the essay analyzes the aesthetic uses of 3D satellite animation on the news during this period, including how these imaging practices meshed with existing discourses such as the clean war, the weaponization of the civic gaze, and others. The essay concludes with thoughts regarding what these practices mean for the efficacy of the deliberative citizen, public life, and the meaning of war.

  18. Integration Of GPS And GLONASS Systems In Geodetic Satellite Measurements

    Science.gov (United States)

    Maciuk, Kamil

    2015-12-01

    The article shows the results of satellites measurements elaborations using GPS & GLONASS signals. The aim of this article is to define the influence of adding GLONASS signals on position determination accuracy. It especially concerns areas with big horizon coverages. Object of the study were analysis of DOP coefficients, code and RTK solutions, and usage of satellite techniques in levelling. The performed studies and analysis show that integrated GPS-GLONASS satellite measurements provide possibility to achieve better results than measurements using single navigation satellite system (GPS).

  19. Options for using Landsat and RapidEye satellite images aiming the water productivity assessments in mixed agro-ecosystems

    Science.gov (United States)

    de C. Teixeira, Antônio H.; Leivas, Janice F.; Bayma-Silva, Gustavo

    2016-10-01

    For water productivity (WP) assessments, the SAFER (Surface Algorithm for Evapotranspiration Retrieving) algorithm for evapotranspiration (ET) and the Monteith's light use efficiency (LUE) model for biomass production (BIO), were applied to Landsat and RapidEye satellite images, in the Brazilian semiarid region, inside the dry season of 2011, in a mixture of irrigated and rainfed agro-ecosystems. Firstly, with the Landsat image, the methodology from which the surface temperature (T0) is derived as a residue in the radiation balance was tested. Low differences were detected, being Landsat ET with the thermal band averaged 0.9 +/- 1.5 mm d-1, while without it the mean value was 0.8 +/- 1.5 mm d-1. The corresponding Landsat BIO values were respectively 28 +/- 59 and 28 +/- 58 kg ha-1 d-1, resulting in mean WP of 1.3 +/- 1.3 kg m-3, in both cases. After having confidence on the residual methodology for retrieving T0 it was applied to the RapidEye image, resulting in average pixel values for ET, BIO and WP of 0.6 +/- 1.5 mm d-1, 26 +/- 58 kg ha-1 d-1 and 0.9 +/- 1.3 kg m-3, representing 75%, 93% and 69% of the Landsat ones obtained without the thermal band. In addition, the Surface Resistance Algorithm (SUREAL) was used to classify the agro-ecosystems into irrigated crops and natural vegetation by using the RapidEye image. The incremental values for ET, BIO and WP in 2011 were 2.0 +/- 1.3 mm d-1, 88 +/- 87 kg ha d-1 and 2.5 +/- 0.6 kg m-3, respectively, as a result of the replacement of the natural species by crops.

  20. Forests through the Eye of a Satellite: Understanding regional forest-cover dynamics using Landsat Imagery

    Science.gov (United States)

    Baumann, Matthias

    Forests are changing at an alarming pace worldwide. Forests are an important provider of ecosystem services that contribute to human wellbeing, including the provision of timber and non-timber products, habitat for biodiversity, recreation amenities. Most prominently, forests serve as a sink for atmospheric carbon dioxide that ultimately helps to mitigate changes in the global climate. It is thus important to understand where, how and why forests change worldwide. My dissertation provides answers to these questions. The overarching goal of my dissertation is to improve our understanding of regional forest-cover dynamics by analyzing Landsat satellite imagery. I answer where forests change following drastic socio-economic shocks by using the breakdown of the Soviet Union as a natural experiment. My dissertation provides innovative algorithms to answer why forests change---because of human activities or because of natural events such as storms. Finally, I will show how dynamic forests are within one year by providing ways to characterize green-leaf phenology from satellite imagery. With my findings I directly contribute to a better understanding of the processes on the Earth's surface and I highlight the importance of satellite imagery to learn about regional and local forest-cover dynamics.

  1. Morphology of Dwarf Galaxies in Isolated Satellite Systems

    Science.gov (United States)

    Ann, Hong Bae

    2017-08-01

    The environmental dependence of the morphology of dwarf galaxies in isolated satellite systems is analyzed to understand the origin of the dwarf galaxy morphology using the visually classified morphological types of 5836 local galaxies with z ≲ 0.01. We consider six sub-types of dwarf galaxies, dS0, dE, dE_{bc}, dSph, dE_{blue}, and dI, of which the first four sub-types are considered as early-type and the last two as late-type. The environmental parameters we consider are the projected distance from the host galaxy (r_{p}), local and global background densities, and the host morphology. The spatial distributions of dwarf satellites of early-type galaxies are much different from those of dwarf satellites of late-type galaxies, suggesting the host morphology combined with r_{p} plays a decisive role on the morphology of the dwarf satellite galaxies. The local and global background densities play no significant role on the morphology of dwarfs in the satellite systems hosted by early-type galaxies. However, in the satellite system hosted by late-type galaxies, the global background densities of dE and dSph satellites are significantly different from those of dE_{bc}, dE_{blue}, and dI satellites. The blue-cored dwarf satellites (dE_{bc}) of early-type galaxies are likely to be located at r_{p} > 0.3 Mpc to keep their cold gas from the ram pressure stripping by the hot corona of early-type galaxies. The spatial distribution of dE_{bc} satellites of early-type galaxies and their global background densities suggest that their cold gas is intergalactic material accreted before they fall into the satellite systems.

  2. Stability of Satellites in Closely Packed Planetary Systems

    CERN Document Server

    Payne, Matthew J; Holman, Matthew J; Perets, Hagai B

    2013-01-01

    We perform numerical integrations of four-body (star, planet, planet, satellite) systems to investigate the stability of satellites in planetary Systems with Tightly-packed Inner Planets (STIPs). We find that the majority of closely-spaced stable two-planet systems can stably support satellites across a range of parameter-space which is only slightly decreased compared to that seen for the single-planet case. In particular, circular prograde satellites remain stable out to $\\sim 0.4 R_H$ (where $R_H$ is the Hill Radius) as opposed to $\\sim 0.5 R_H$ in the single-planet case. A similarly small restriction in the stable parameter-space for retrograde satellites is observed, where planetary close approaches in the range 2.5 to 4.5 mutual Hill radii destabilize most satellites orbits only if $a\\sim 0.65 R_H$. In very close planetary pairs (e.g. the 12:11 resonance) the addition of a satellite frequently destabilizes the entire system, causing extreme close-approaches and the loss of satellites over a range of cir...

  3. The Human Eye Position Control System in a Rehabilitation Setting

    Directory of Open Access Journals (Sweden)

    Yvonne Nolan

    2005-01-01

    Full Text Available Our work at Ireland’s National Rehabilitation Hospital involves designing communication systems for people suffering from profound physical disabilities. One such system uses the electro-oculogram, which is an (x,y system of voltages picked up by pairs of electrodes placed, respectively, above and below and on either side of the eyes. The eyeball has a dc polarisation between cornea and back, arising from the photoreceptor rods and cones in the retina. As the eye rotates, the varying voltages projected onto the electrodes drive a cursor over a mimic keyboard on a computer screen. Symbols are selected with a switching action derived, for example, from a blink. Experience in using this mode of communication has given us limited facilities to study the eye position control system. We present here a resulting new feedback model for rotation in either the vertical or the horizontal plane, which involves the eyeball controlled by an agonist-antagonist muscle pair, modelled by a single equivalent bidirectional muscle with torque falling off linearly with angular velocity. We have incorporated muscle spindles and have tuned them by pole assignment associated with an optimum stability criterion.

  4. Joint Polar Satellite System Common Ground System Overview

    Science.gov (United States)

    Jamilkowski, M. L.; Smith, D. C.

    2011-12-01

    Jointly acquired by NOAA & NASA, the next-generation civilian environmental satellite system, Joint Polar Satellite System (JPSS), will supply the afternoon orbit & ground system of the restructured NPOESS program. JPSS will replace NOAA's current POES satellites and the ground processing part of both POES & DoD's Defense Weather Satellite System (DWSS)(DMSP replacement). JPSS sensors will collect meteorological, oceanographic, climatological and solar-geophysical data. The ground system, or JPSS Common Ground System (CGS), has 6 integrated product teams/segments: Command, Control & Communications (C3S); Interface Data Processing (IDPS); Field Terminal (FTS); Systems Engineering, Integration & Test (SEIT); Operations & Support (O&S); and Sustainment developed by Raytheon Intelligence & Information Systems. The IDPS will process JPSS data to provide Environmental Data Records (EDRs) to NOAA & DoD processing centers beginning with the NPOESS Preparatory Project (NPP) and through JPSS & DWSS eras. C3S will: manage overall JPSS & DWSS missions from control/status of space/ground assets to ensure timely delivery of high-quality data to IDPS; provide globally-distributed ground assets to collect/transport mission, telemetry and command data between satellites & processing locations; provide all commanding & state-of-health monitoring functions of NPP, JPSS and DWSS satellites, and delivery of mission data to each Central IDP and monitor/report system-wide health/status and data communications with external systems and between CGS segments. SEIT leads the overall effort, including: manage/coordinate/execute JPSS CGS activities with NASA participation/oversight; plan/conduct all activities related to systems engineering, develop & ensure completeness of JPSS CGS functional & technical baselines and perform integration, deployment, testing and verification; sponsor/support modeling & simulation, performance analysis and trade studies; provide engineering for the product

  5. Analysis of Maritime Mobile Satellite Communication Systems

    Science.gov (United States)

    1988-12-01

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

  6. Isolated Galaxies and Isolated Satellite Systems

    CERN Document Server

    Ann, H B; Choi, Yun-Young

    2009-01-01

    We search for isolated galaxies using a volume-limited sample of galaxies with 0.02r_{vir,nei} and \\rho <\\bar{\\rho} well segregates the CIG galaxies. We confirm the morphology conformity between the host and their satellites, which suggests importance of hydrodynamic interaction among galaxies within their virial radii in galaxy evolution.

  7. Architecture analysis of the simplified libration point satellite navigation system

    Science.gov (United States)

    Zhang, Lei; Xu, Bo

    2016-10-01

    The libration point satellite navigation system is a novel navigation architecture that consists of satellites located in periodic orbits around the Earth-Moon libration points. Superiorities of the proposed system lie in its autonomy and extended navigation capability, which have been proved in our previous works. Based on the candidate architectures obtained before, a detailed analysis of the simplified libration point satellite navigation system, i.e. the Earth-Moon L1,2 two-satellite constellation, is conducted in this work. Firstly, relation between orbits amplitude is derived for the candidate two-satellite constellations to ensure continuous crosslink measurements between libration point satellites. Then, with the use of a reference lunar exploration mission scenario, navigation performances of different constellation configurations are evaluated by Monte-Carlo simulations. The simulation results indicate that the amplitude and initial phase combinations of libration point orbits have direct effect on the performance of the two-satellite constellations. By using a cooperative evolutionary algorithm for configuration parameter optimization, some optimal constellations are finally obtained for the simplified navigation architecture. The results obtained in this paper may be a reference for future system design.

  8. Use of CDMA access technology in mobile satellite systems

    Science.gov (United States)

    Ramasastry, Jay; Wiedeman, Bob

    1995-01-01

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

  9. Intelligent fault isolation and diagnosis for communication satellite systems

    Science.gov (United States)

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

    1992-01-01

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

  10. Propagation considerations in the American Mobile Satellite system design

    Science.gov (United States)

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

    1993-01-01

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

  11. Design of House Keeping System for a Certain Micro Satellite

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    This paper presents the design of hardware and software of the house keeping system for a certain microsatellite. The system uses microelectronic technique, large scale integrated circuits, processors and computers which has the advantages of strong function, high flexibility and reliability, It satisfies the requirements for efficient performance,light weight, small volume,and low consumption of power for microsatellite.

  12. Satellite Attitude Control System Design considering the Fuel Slosh Dynamics

    Directory of Open Access Journals (Sweden)

    Luiz Carlos Gadelha de Souza

    2014-01-01

    Full Text Available The design of the satellite attitude control system (ACS becomes more complex when the satellite structure has different type of components like, flexible solar panels, antennas, mechanical manipulators, and tanks with fuel. A crucial interaction can occur between the fuel slosh motion and the satellite rigid motion during translational and/or rotational manoeuvre since these interactions can change the satellite centre of mass position damaging the ACS pointing accuracy. Although, a well-designed controller can suppress such disturbances quickly, the controller error pointing may be limited by the minimum time necessary to suppress such disturbances thus affecting the satellite attitude acquisition. As a result, the design of the satellite controller needs to explore the limits between the conflicting requirements of performance and robustness. This paper investigates the effects of the interaction between the liquid motion (slosh and the satellite dynamics in order to predict what the damage to the controller performance and robustness is. The fuel slosh dynamics is modelled by a pendulum which parameters are identified using the Kalman filter technique. This information is used to design the satellite controller by the linear quadratic regulator (LQR and linear quadratic Gaussian (LQG methods to perform a planar manoeuvre assuming thrusters are actuators.

  13. A Hand-Eye Vision Measuring System for Articulate Robots

    Institute of Scientific and Technical Information of China (English)

    岁波; 都东; 陈强; 韩翔宇; 王力; 张骅

    2004-01-01

    To make dynamic measurements for an articulate robot, a hand-eye vision measuring system is built up.This system uses two charge coupled device (CCD) cameras mounted on the end-effector of the robot.System analysis is based on the stereovision theory and line-matching technology, using a computer to evaluate the dynamic performance parameters of an articulate robot from the two images captured by the two cameras.The measuring procedure includes four stages, namely, calibration, sampling, image processing, and calculation.The path accuracy of an articulate industrial robot was measured by this system.The results show that this system is a low-cost, easy to operate, and simple system for the dynamic performance testing of articulate robots.

  14. 622 Mbps High-speed satellite communication system for WINDS

    Science.gov (United States)

    Ogawa, Yasuo; Hashimoto, Yukio; Yoshimura, Naoko; Suzuki, Ryutaro; Gedney, Richard T.; Dollard, Mike

    2006-07-01

    WINDS is the experimental communications satellite currently under joint development by Japanese Aerospace Exploration Agency (JAXA) and the National Institute of Information and Communications Technology (NICT). The high-speed satellite communication system is very effective for quick deployment of high-speed networks economically. The WINDS will realize ultra high-speed networking and demonstrate operability of satellite communication systems in high-speed internet. NICT is now developing high-speed satellite communication system for WINDS. High-speed TDMA burst modem with high performance TPC error correction is underdevelopment. Up to the DAC on the transmitter and from the ADC on the receiver, all modem functions are performed in the digital processing technology. Burst modem has been designed for a user data rate up to 1244 Mbps. NICT is developing the digital terminal as a user interface and a network controller for this earth station. High compatibility with the Internet will be provided.

  15. Engineering satellite-based navigation and timing global navigation satellite systems, signals, and receivers

    CERN Document Server

    Betz, J

    2016-01-01

    This book describes the design and performance analysis of satnav systems, signals, and receivers. It also provides succinct descriptions and comparisons of all the world’s satnav systems. Its comprehensive and logical structure addresses all satnav signals and systems in operation and being developed. Engineering Satellite-Based Navigation and Timing: Global Navigation Satellite Systems, Signals, and Receivers provides the technical foundation for designing and analyzing satnav signals, systems, and receivers. Its contents and structure address all satnav systems and signals: legacy, modernized, and new. It combines qualitative information with detailed techniques and analyses, providing a comprehensive set of insights and engineering tools for this complex multidisciplinary field. Part I describes system and signal engineering including orbital mechanics and constellation design, signal design principles and underlying considerations, link budgets, qua tifying receiver performance in interference, and e...

  16. Towards eye-safe standoff Raman imaging systems

    Science.gov (United States)

    Glimtoft, Martin; Bââth, Petra; Saari, Heikki; Mäkynen, Jussi; Näsilä, Antti; Östmark, Henric

    2014-05-01

    Standoff Raman imaging systems have shown the ability to detect single explosives particles. However, in many cases, the laser intensities needed restrict the applications where they can be safely used. A new generation imaging Raman system has been developed based on a 355 nm UV laser that, in addition to eye safety, allows discrete and invisible measurements. Non-dangerous exposure levels for the eye are several orders of magnitude higher in UVA than in the visible range that previously has been used. The UV Raman system has been built based on an UV Fabry-Perot Interferometer (UV-FPI) developed by VTT. The design allows for precise selection of Raman shifts in combination with high out-of-band blocking. The stable operation of the UV-FPI module under varying environmental conditions is arranged by controlling the temperature of the module and using a closed loop control of the FPI air gap based on capacitive measurement. The system presented consists of a 3rd harmonics Nd:YAG laser with 1.5 W average output at 1000 Hz, a 200 mm Schmidt-Cassegrain telescope, UV-FPI filter and an ICCD camera for signal gating and detection. The design principal leads to a Raman spectrum in each image pixel. The system is designed for field use and easy manoeuvring. Preliminary results show that in measurements of <60 s on 10 m distance, single AN particles of <300 μm diameter can be identified.

  17. Applying principles of health system strengthening to eye care

    Directory of Open Access Journals (Sweden)

    Karl Blanchet

    2012-01-01

    Full Text Available Understanding Health systems have now become the priority focus of researchers and policy makers, who have progressively moved away from a project-centred perspectives. The new tendency is to facilitate a convergence between health system developers and disease-specific programme managers in terms of both thinking and action, and to reconcile both approaches: one focusing on integrated health systems and improving the health status of the population and the other aiming at improving access to health care. Eye care interventions particularly in developing countries have generally been vertically implemented (e.g. trachoma, cataract surgeries often with parallel organizational structures or specialised disease specific services. With the emergence of health system strengthening in health strategies and in the service delivery of interventions there is a need to clarify and examine inputs in terms governance, financing and management. This present paper aims to clarify key concepts in health system strengthening and describe the various components of the framework as applied in eye care interventions.

  18. IMPGSS - International Medical Program Global Satellite System

    Science.gov (United States)

    2004-02-01

    additional comments regarding the significance of working with Tachyon and NASK under this Contract). 5.2.5 Requirements - Country/Region Assessments...services on a tentative exploratory basis by Tachyon ]. 5.2.7 Program Development Deliverable A 007 This is currently summarized in the Program Content...based satellite transmissions and transmission pricing based on segmented, limited use data volumes via Tachyon . " A more involved use of evaluation

  19. A Survey of Satellite Communications System Vulnerabilities

    Science.gov (United States)

    2008-06-01

    Myers, Raymond M. Nuber, Jaime L. Prieto , Jr., and Eric R. Wiswell, “Fast Packet Vs. Circuit Switch and Bent Pipe Satellite Network Architectures...2008. 81. Howell, Alan , “INMARSAT HORIZONS PROGRAM,” Institution of Electrical Engineers, Savoy Place, London, 1998. 82. http://www.infosec.gov.hk...ntia-rpt/02- 393/02-393.pdf, NTIA Report 02-393, pages 1-20, May 2002. 134. Sardella, Alan , “Securing Provider Backbone Networks: Packet Filters

  20. Eye vision system using programmable micro-optics and micro-electronics

    Science.gov (United States)

    Riza, Nabeel A.; Amin, M. Junaid; Riza, Mehdi N.

    2014-02-01

    Proposed is a novel eye vision system that combines the use of advanced micro-optic and microelectronic technologies that includes programmable micro-optic devices, pico-projectors, Radio Frequency (RF) and optical wireless communication and control links, energy harvesting and storage devices and remote wireless energy transfer capabilities. This portable light weight system can measure eye refractive powers, optimize light conditions for the eye under test, conduct color-blindness tests, and implement eye strain relief and eye muscle exercises via time sequenced imaging. Described is the basic design of the proposed system and its first stage system experimental results for vision spherical lens refractive error correction.

  1. An operational satellite remote sensing system for ocean fishery

    Institute of Scientific and Technical Information of China (English)

    MAOZhihua; ZHUQiankun; PANDelu

    2004-01-01

    Ocean environmental information is very important to supporting the fishermen in fishing and satellite remote sensing technology can provide it in large scale and in near real-time. Ocean fishery locations are always far away beyond the coverage of the satellite data received by a land-based satellite receiving station. A nice idea is to install the satellite ground station on a fishing boat. When the boat moves to a fishery location, the station can receive the satellite data to cover the fishery areas. One satellite remote sensing system was once installed in a fishing boat and served fishing in the North Pacific fishery areas when the boat stayed there. The system can provide some oceanic environmental charts such as sea surface temperature (SST) and relevant derived products which are in most popular use in fishery industry. The accuracy of SST is the most important and affects the performance of the operational system, which is found to be dissatisfactory. Many factors affect the accuracy of SST and it is difficult to increase the accuracy by SST retrieval algorithms and clouds detection technology. A new technology of temperature error control is developed to detect the abnormity of satellite-measured SST. The performance of the technology is evaluated to change the temperature bias from-3.04 to 0.05 ℃ and the root mean square (RMS) from 5.71 to 1.75 ℃. It is suitable for employing in an operational satellite-measured SST system and improves the performance of the system in fishery applications. The system has been running for 3 a and proved to be very useful in fishing. It can help to locate the candidates of the fishery areas and monitor the typhoon which is very dangerous to the safety of fishing boats.

  2. Tsinghua-1 Micro-Satellite Power System Architecture and Design

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    The Tsinghua-1 Micro-satellite, the first satellite made by Tsinghua University, was launched in 2000. The power system of the Tsinghua-1 Micro-satellite is one of the most important subsystems. It provides all the power for the satellite platform and the payloads. The power system design includes the regulation,protection and distribution of a 4 × 35 W solar array and 7 Ah NiCd batteries. This subsystem essentially offerstwo buses: an unregulated 14 V bus and a regulated 5 V bus. All distributed power lines to the users areprotected by current tripping switches. In addition, some essential loads, such as the tele-command system,are supplied through fuses. The Tsinghua-1 Micro-satellite power system provides an efficient, flexible,reliable, and cost-effective solution for small satellites in low earth orbit. A better maximum power pointtracking method has been used to increase reliability margins and to increase the efficiency of the powersystem. The power system reliability was evaluated using several different tests, such as the power boardtest, the assembly integrate test (AIT), the electromagnetic compatibility (EMC) test and the thermal vacuumtest (TVT).``

  3. Referral system for hard exudates in eye fundus.

    Science.gov (United States)

    Naqvi, Syed Ali Gohar; Zafar, Muhammad Faisal; Haq, Ihsan ul

    2015-09-01

    Hard exudates are one of the most common anomalies/artifacts found in the eye fundus of patients suffering from diabetic retinopathy. These exudates are the major cause of loss of sight or blindness in people having diabetic retinopathy. Diagnosis of hard exudates requires considerable time and effort of an ophthalmologist. The ophthalmologists have become overloaded, so that there is a need for an automated diagnostic/referral system. In this paper a referral system for the hard exudates in the eye-fundus images has been presented. The proposed referral system works by combining different techniques like Scale Invariant Feature Transform (SIFT), K-means Clustering, Visual Dictionaries and Support Vector Machine (SVM). The system was also tested with Back Propagation Neural Network as a classifier. To test the performance of the system four fundus image databases were used. One publicly available image database was used to compare the performance of the system to the existing systems. To test the general performance of the system when the images are taken under different conditions and come from different sources, three other fundus image databases were mixed. The evaluation of the system was also performed on different sizes of the visual dictionaries. When using only one fundus image database the area under the curve (AUC) of maximum 0.9702 (97.02%) was achieved with accuracy of 95.02%. In case of mixed image databases an AUC of 0.9349 (93.49%) was recorded having accuracy of 87.23%. The results were compared to the existing systems and were found better/comparable. Copyright © 2015 Elsevier Ltd. All rights reserved.

  4. The Submillimeter Wave Astronomy Satellite (SWAS) solar array system

    Science.gov (United States)

    Sneiderman, Gary

    1993-01-01

    The SWAS (Submillimeter Wave Astronomy Satellite) solar array system is described. It is an innovative approach to meet the missions requirements. The SWAS satellite provides a three axis stabilized platform to survey a variety of galactic cloud structures. This system includes highly reliable, lightweight launch latch, deployment, and lock mechanisms, and solar array panels that provide the maximum solar cell area. The design of the solar arrays are the result of system trades that included instrument and spacecraft thermal constraints, attitude control system maneuvering rates and pointing accuracies, the power system, and the spacecraft structure.

  5. 3-dimensional current collection model. [of Tethered Satellite System 1

    Science.gov (United States)

    Hwang, Kai-Shen; Shiah, A.; Wu, S. T.; Stone, N.

    1992-01-01

    A three-dimensional, time dependent current collection model of a satellite has been developed for the TSS-1 system. The system has been simulated particularly for the Research of Plasma Electrodynamics (ROPE) experiment. The Maxwellian distributed particles with the geomagnetic field effects are applied in this numerical simulation. The preliminary results indicate that a ring current is observed surrounding the satellite in the equatorial plane. This ring current is found between the plasma sheath and the satellite surface and is oscillating with a time scale of approximately 1 microsec. This is equivalent to the electron plasma frequency. An hour glass shape of electron distribution was observed when the viewing direction is perpendicular to the equatorial plane. This result is consistent with previous findings from Linson (1969) and Antoniades et al. (1990). Electrons that are absorbed by the satellite are limited from the background ionosphere as indicated by Parker and Murphy (1967).

  6. Information content in reflected global navigation satellite system signals

    DEFF Research Database (Denmark)

    Høeg, Per; Carlstrom, Anders

    2011-01-01

    The direct signals from satellites in global satellite navigation satellites systems (GNSS) as, GPS, GLONASS and GALILEO, constitute the primary source for positioning, navigation and timing from space. But also the reflected GNSS signals contain an important information content of signal travel...... times and the characteristics of the reflecting surfaces and structure. Ocean reflected signals from GNSS satellite systems reveal the mean height, the significant wave height and the roughness of the ocean. The estimated accuracy of the average surface height can be as low as 10 cm. For low elevations......, the signals reveal the incoherent scatter process at the reflection zone. By using open-loop high-precision GNSS receivers, it is possible to provide the in-phase and quadrature components of the signal at high sample rates, which enables investigation of the spectral signatures of the observations...

  7. Phase control system concepts and simulations. [solar power satellite system

    Science.gov (United States)

    Lindsay, V. C.

    1980-01-01

    A phase control system concept for a solar power satellite is proposed which partitions the system into three major levels. The first level of phase control consists of a reference phase distribution system implemented in the form of phase distribution tree structure. The major purpose of the tree structure is to electronically compensate for the phase shift due to the transition path lengths from the center of the spacetenna to each phase control center located in each subarray. In the reference system, this is accomplished using the master slave returnable timing system technique. The second level of phase control consists of the beam steering and microwave power generating system which houses the power transponders. This transponder consists of a set of phase conjugation multipliers driven by the reference phase distribution system output and the output of a pilot spread spectrum receiver which accepts the received pilot via a diplexer connected to a separate receive horn or the subarray itself. The output of the phase conjugation circuits serve as inputs to the third level of the phase control system. The third level of phase control is associated with maintaining an equal and constant phase shift through the microwave power amplifier devices while minimizing the associated phase noise effects on the generated power beam. This is accomplished by providing a phase locked loop around each high power amplifier.

  8. Eyes in the sky: a comparative spatial analysis of aerial and satellite surveillance of east coast Canadian oil pollution

    Energy Technology Data Exchange (ETDEWEB)

    Lieske, David J. [Mount Allison University (Canada)], email: dlieske@mta.ca; Mahoney, Matthew [Environment Canada (Canada); Wilhelm, Sabina I. [Canadian Wildlife Service, Environment Canada (Canada); Weir, Laurie [Marine and Ice Services, Meteorological Service of Canada, Environment Canada (Canada); O' Hara, Patrick [Canadian Wildlife Service, Institute of Ocean Science (canada)

    2011-07-01

    This study offers an insight into three different oil spill detection schemes used in Canadian waters: visually unaided aerial surveillance, SLAR-assisted aerial surveillance, and RADARSAT-based image processing. The main purpose of this study is to compare the effectiveness of these schemes with respect to spill surveillance methodology, and to make recommendations for future planning techniques. In order to quantify the surveillance capacity of each method, flight paths had to be generated, followed by calculating oil loading. Flight paths were generated manually from images and records for the first approach, while this information was extracted from digitalized records for the second and third approaches. Results showed that SLAR technology increased the efficiency of NASP aircraft in spill detection by increasing the area surveyed and by its not having to rely on naked-eye spotting of the spills. Moreover, ISTOP widened the aircraft coverage range due to its satellite-based imagery, which can operate at night as well as in daylight.

  9. Hybrid Atom Electrostatic System for Satellite Geodesy

    Science.gov (United States)

    Zahzam, Nassim; Bidel, Yannick; Bresson, Alexandre; Huynh, Phuong-Anh; Liorzou, Françoise; Lebat, Vincent; Foulon, Bernard; Christophe, Bruno

    2017-04-01

    The subject of this poster comes within the framework of new concepts identification and development for future satellite gravity missions, in continuation of previously launched space missions CHAMP, GRACE, GOCE and ongoing and prospective studies like NGGM, GRACE 2 or E-GRASP. We were here more focused on the inertial sensors that complete the payload of such satellites. The clearly identified instruments for space accelerometry are based on the electrostatic technology developed for many years by ONERA and that offer a high level of performance and a high degree of maturity for space applications. On the other hand, a new generation of sensors based on cold atom interferometry (AI) is emerging and seems very promising in this context. These atomic instruments have already demonstrated on ground impressive results, especially with the development of state-of-the-art gravimeters, and should reach their full potential only in space, where the microgravity environment allows long interaction times. Each of these two types of instruments presents their own advantages which are, for the electrostatic sensors (ES), their demonstrated short term sensitivity and their high TRL, and for AI, amongst others, the absolute nature of the measurement and therefore no need for calibration processes. These two technologies seem in some aspects very complementary and a hybrid sensor bringing together all their assets could be the opportunity to take a big step in this context of gravity space missions. We present here the first experimental association on ground of an electrostatic accelerometer and an atomic accelerometer and underline the interest of calibrating the ES instrument with the AI. Some technical methods using the ES proof-mass as the Raman Mirror seem very promising to remove rotation effects of the satellite on the AI signal. We propose a roadmap to explore further in details and more rigorously this attractive hybridization scheme in order to assess its potential

  10. Guidance and Control System for a Satellite Constellation

    Science.gov (United States)

    Bryson, Jonathan Lamar; Cox, James; Mays, Paul Richard; Neidhoefer, James Christian; Ephrain, Richard

    2010-01-01

    A distributed guidance and control algorithm was developed for a constellation of satellites. The system repositions satellites as required, regulates satellites to desired orbits, and prevents collisions. 1. Optimal methods are used to compute nominal transfers from orbit to orbit. 2. Satellites are regulated to maintain the desired orbits once the transfers are complete. 3. A simulator is used to predict potential collisions or near-misses. 4. Each satellite computes perturbations to its controls so as to increase any unacceptable distances of nearest approach to other objects. a. The avoidance problem is recast in a distributed and locally-linear form to arrive at a tractable solution. b. Plant matrix values are approximated via simulation at each time step. c. The Linear Quadratic Gaussian (LQG) method is used to compute perturbations to the controls that will result in increased miss distances. 5. Once all danger is passed, the satellites return to their original orbits, all the while avoiding each other as above. 6. The delta-Vs are reasonable. The controller begins maneuvers as soon as practical to minimize delta-V. 7. Despite the inclusion of trajectory simulations within the control loop, the algorithm is sufficiently fast for available satellite computer hardware. 8. The required measurement accuracies are within the capabilities of modern inertial measurement devices and modern positioning devices.

  11. Development of SPIES (Space Intelligent Eyeing System) for smart vehicle tracing and tracking

    Science.gov (United States)

    Abdullah, Suzanah; Ariffin Osoman, Muhammad; Guan Liyong, Chua; Zulfadhli Mohd Noor, Mohd; Mohamed, Ikhwan

    2016-06-01

    SPIES or Space-based Intelligent Eyeing System is an intelligent technology which can be utilized for various applications such as gathering spatial information of features on Earth, tracking system for the movement of an object, tracing system to trace the history information, monitoring driving behavior, security and alarm system as an observer in real time and many more. SPIES as will be developed and supplied modularly will encourage the usage based on needs and affordability of users. SPIES are a complete system with camera, GSM, GPS/GNSS and G-Sensor modules with intelligent function and capabilities. Mainly the camera is used to capture pictures and video and sometimes with audio of an event. Its usage is not limited to normal use for nostalgic purpose but can be used as a reference for security and material of evidence when an undesirable event such as crime occurs. When integrated with space based technology of the Global Navigational Satellite System (GNSS), photos and videos can be recorded together with positioning information. A product of the integration of these technologies when integrated with Information, Communication and Technology (ICT) and Geographic Information System (GIS) will produce innovation in the form of information gathering methods in still picture or video with positioning information that can be conveyed in real time via the web to display location on the map hence creating an intelligent eyeing system based on space technology. The importance of providing global positioning information is a challenge but overcome by SPIES even in areas without GNSS signal reception for the purpose of continuous tracking and tracing capability

  12. Satellite augmentation of cellular type mobile radio telephone systems

    Science.gov (United States)

    Anderson, Roy E.

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

  13. Applications of two-way satellite time and frequency transfer in the BeiDou navigation satellite system

    Science.gov (United States)

    Zhou, ShanShi; Hu, XiaoGong; Liu, Li; Guo, Rui; Zhu, LingFeng; Chang, ZhiQiao; Tang, ChengPan; Gong, XiuQiang; Li, Ran; Yu, Yang

    2016-10-01

    A two-way satellite time and frequency transfer (TWSTFT) device equipped in the BeiDou navigation satellite system (BDS) can calculate clock error between satellite and ground master clock. TWSTFT is a real-time method with high accuracy because most system errors such as orbital error, station position error, and tropospheric and ionospheric delay error can be eliminated by calculating the two-way pseudorange difference. Another method, the multi-satellite precision orbit determination (MPOD) method, can be applied to estimate satellite clock errors. By comparison with MPOD clock estimations, this paper discusses the applications of the BDS TWSTFT clock observations in satellite clock measurement, satellite clock prediction, navigation system time monitor, and satellite clock performance assessment in orbit. The results show that with TWSTFT clock observations, the accuracy of satellite clock prediction is higher than MPOD. Five continuous weeks of comparisons with three international GNSS Service (IGS) analysis centers (ACs) show that the reference time difference between BeiDou time (BDT) and golbal positoning system (GPS) time (GPST) realized IGS ACs is in the tens of nanoseconds. Applying the TWSTFT clock error observations may obtain more accurate satellite clock performance evaluation in the 104 s interval because the accuracy of the MPOD clock estimation is not sufficiently high. By comparing the BDS and GPS satellite clock performance, we found that the BDS clock stability at the 103 s interval is approximately 10-12, which is similar to the GPS IIR.

  14. Improvements and Extensions for Joint Polar Satellite System Algorithms

    Science.gov (United States)

    Grant, K. D.

    2016-12-01

    The National Oceanic and Atmospheric Administration (NOAA) and National Aeronautics and Space Administration (NASA) are jointly acquiring the next-generation civilian weather satellite system: the Joint Polar Satellite System (JPSS). JPSS replaced the afternoon orbit component and ground processing of the old POES system managed by NOAA. JPSS satellites carry sensors designed to collect meteorological, oceanographic, climatological, and solar-geophysical observations of the earth, atmosphere, and space. The ground processing system for JPSS is the Common Ground System (CGS), and provides command, control, and communications (C3), data processing and product delivery. CGS's data processing capability provides environmental data products (Sensor Data Records (SDRs) and Environmental Data Records (EDRs)) to the NOAA Satellite Operations Facility. The first satellite in the JPSS constellation, S-NPP, was launched in October 2011. The second satellite, JPSS-1, is scheduled for launch in January 2017. During a satellite's calibration and validation (Cal/Val) campaign, numerous algorithm updates occur. Changes identified during Cal/Val become available for implementation into the operational system for both S-NPP and JPSS-1. In addition, new capabilities, such as higher spectral and spatial resolution, will be exercised on JPSS-1. This paper will describe changes to current algorithms and products as a result of S-NPP Cal/Val and related initiatives for improved capabilities. Improvements include Cross Track Infrared Sounder high spectral processing, extended spectral and spatial ranges for Ozone Mapping and Profiler Suite ozone Total Column and Nadir Profiles, and updates to Vegetation Index, Snow Cover, Active Fires, Suspended Matter, and Ocean Color. Updates will include Sea Surface Temperature, Cloud Mask, Cloud Properties, and other improvements.

  15. SOFT project: a new forecasting system based on satellite data

    Science.gov (United States)

    Pascual, Ananda; Orfila, A.; Alvarez, Alberto; Hernandez, E.; Gomis, D.; Barth, Alexander; Tintore, Joaquim

    2002-01-01

    The aim of the SOFT project is to develop a new ocean forecasting system by using a combination of satellite dat, evolutionary programming and numerical ocean models. To achieve this objective two steps are proved: (1) to obtain an accurate ocean forecasting system using genetic algorithms based on satellite data; and (2) to integrate the above new system into existing deterministic numerical models. Evolutionary programming will be employed to build 'intelligent' systems that, learning form the past ocean variability and considering the present ocean state, will be able to infer near future ocean conditions. Validation of the forecast skill will be carried out by comparing the forecasts fields with satellite and in situ observations. Validation with satellite observations will provide the expected errors in the forecasting system. Validation with in situ data will indicate the capabilities of the satellite based forecast information to improve the performance of the numerical ocean models. This later validation will be accomplished considering in situ measurements in a specific oceanographic area at two different periods of time. The first set of observations will be employed to feed the hybrid systems while the second set will be used to validate the hybrid and traditional numerical model results.

  16. Globe-fixation system for animal eye practice.

    Science.gov (United States)

    Mohammadi, S Farzad; Mazouri, Arash; Rahman-A, Nazanin; Jabbarvand, Mahmoud; Peyman, Gholam A

    2011-01-01

    We designed a globe-fixation system for use with animal eyes for surgical skills training. The system core is a cup with an adjustable aperture. Vacuum is exerted through the cup to capture the globe at the preequatorial region. The cup rides over a hollow base, sliding on its opening spurs. A ballast is screwed to the end of the thread of the cup to create tactile feedback and create a tendency to return to the primary position. The system provides optimum versatility for the practice of anterior segment procedures, namely stability, rotation, a tendency to return to the primary position, globe pressure adjustability, and a modifiable orbit size. Disclosures are found in the footnotes. Copyright © 2011 ASCRS and ESCRS. Published by Elsevier Inc. All rights reserved.

  17. [Systemic cardiovascular risk assessment. Conventional or eye fundus-based?].

    Science.gov (United States)

    Wolf, A; Kernt, M; Kampik, A; Neubauer, A S

    2010-09-01

    Several systemic cardiovascular (CV) risk assessment algorithms exist, of which the ESC HeartScore, Framingham and PROCAM are the most frequently applied in Germany. The risk estimates generated differ and take a number of different risk factors into consideration. Due to existing homology of retinal vessels and brain vessels, eye fundus examination is a promising approach to improving risk prediction. Large cohort studies investigated retinal vascular changes, including arteriovenous ratio, as well as signs of retinopathy such as cotton-wool spots, microaneurysms, or retinal hemorrhages for their ability to predict systemic cardiovascular events. While signs of retinopathy proved to have high predictive power (but are rarely diagnosed,) the retinal vascular changes investigated could contribute little to enhancing systemic CV risk prediction. A number of new and promising approaches based on static and dynamic retinal analysis exist, but still need to be validated prospectively.

  18. The eyes of man as a photic bisensor system

    NARCIS (Netherlands)

    Verheijen, F.J.; Fingal, J.A.

    1982-01-01

    Non-patterned photic stimulation of the eyes of human subjects was obtained by homogeneous illumination of the closed eyes. The subjects perceived a difference between the stimulation intensity of the left and of the right eye as a field of view consisting of a bright and a dark half, adjoined acros

  19. The eyes of man as a photic bisensor system

    NARCIS (Netherlands)

    Verheijen, F.J.; Fingal, J.A.

    1982-01-01

    Non-patterned photic stimulation of the eyes of human subjects was obtained by homogeneous illumination of the closed eyes. The subjects perceived a difference between the stimulation intensity of the left and of the right eye as a field of view consisting of a bright and a dark half, adjoined acros

  20. The Saturn System's Icy Satellites: New Results from Cassini

    Science.gov (United States)

    Lopes-Gautier, Rosaly M.; Buratti, Bonnie; Hendrix, A. R.

    2008-01-01

    Cassini-Huygens is a multidisciplinary, international planetary mission consisting of an orbiting spacecraft and a probe. The Huygens probe successfully landed on Titan's surface on January 14, 2005, while the orbiter has performed observations of Saturn, its rings, satellites, and magnetosphere since it entered orbit around Saturn on July 1, 2004. The Cassini mission has been prolific in its scientific discoveries about the Saturn system. In this special section, we present new mission results with a focus on the 'icy satellites,' which we define as all Saturn's moons with the exception of Titan. The results included in this section have come out of the Cassini SOST--Satellites Orbiter Science Team--a multi-instrument and multidiscipline group that works together to better understand the icy satellites and their interactions with Saturn and its rings. Other papers included in this issue present ground-based observations and interior modeling of these icy moons.

  1. Spatial Cloud Detection and Retrieval System for Satellite Images

    Directory of Open Access Journals (Sweden)

    Ayman Nasr

    2013-01-01

    Full Text Available In last the decade we witnessed a large increase in data generated by earth observing satellites. Hence, intelligent processing of the huge amount of data received by hundreds of earth receiving stations, with specific satellite image oriented approaches, presents itself as a pressing need. One of the most important steps in earlier stages of satellite image processing is cloud detection. Satellite images having a large percentage of cloud cannot be used in further analysis. While there are many approaches that deal with different semantic meaning, there are rarely approaches that deal specifically with cloud detection and retrieval. In this paper we introduce a novel approach that spatially detect and retrieve clouds in satellite images using their unique properties .Our approach is developed as spatial cloud detection and retrieval system (SCDRS that introduce a complete framework for specific semantic retrieval system. It uses a Query by polygon (QBP paradigm for the content of interest instead of using the more conventional rectangular query by image approach. First, we extract features from the satellite images using multiple tile sizes using spatial and textural properties of cloud regions. Second, we retrieve our tiles using a parametric statistical approach within a multilevel refinement process. Our approach has been experimentally validated against the conventional ones yielding enhanced precision and recall rates in the same time it gives more precise detection of cloud coverage regions.

  2. Dependent surveillance through an experimental satellite data link system

    Science.gov (United States)

    Cobley, G. A.

    The development and testing of an experimental dependent aircraft-surveillance system using a satellite data link is reported. In this system, the aircraft position is determined onboard using GPS or inertial navigation, enclosed in a message block using a data-link system, and transmitted to an Inmarsat GEO communication satellites; the ground station receives and analyzes the data to keep constant track of the aircraft position. The hardware implementation and the results of demonstrations performed on flights from Iowa to Wisconsin and the North Atlantic are discussed, and diagrams and maps are provided.

  3. Dry Eye and Corneal Langerhans Cells in Systemic Lupus Erythematosus

    Directory of Open Access Journals (Sweden)

    Miklós D. Resch

    2015-01-01

    Full Text Available Purpose. Investigation of dry eye and corneal Langerhans cells (LCs in systemic lupus erythematosus (SLE. Methods. Prospective consecutive case series of 27 SLE patients and 27 control subjects. Dry eye was evaluated by lid-parallel conjunctival folds (LIPCOF, Schirmer test, tear break-up time (TBUT, and ocular surface disease index (OSDI questionnaire. In vivo investigation of corneal LCs density and morphology (LCM was performed with confocal corneal microscopy (Heidelberg Retina Tomograph with Rostock Cornea Module. Results. Tear production and stability were pathological in SLE subjects compared to control (Schirmer: 8.45 ± 9.82 mm/5 min versus 11.67 ± 3.21 mm/5 min; TBUT: 6.86 ± 3.53 s versus 11.09 ± 3.37 s. OSDI was significantly greater in SLE patients (25.95 ± 17.92 than in controls (11.06 ± 7.18. Central LC density was greater in SLE patients (43.08 ± 48.67 cell/mm2 than in controls (20.57 ± 21.04 cell/mm2. There was no difference in the peripheral LC density (124.78 ± 165.39 versus 78.00 ± 39.51 cell/mm2. LCM was higher in SLE patients in the centre (1.43 ± 0.79 and in the periphery (2.89 ± 0.42 compared to controls (centre: 1.00 ± 0.69, periphery: 2.35 ± 0.54. Conclusions. Significant changes in dry eye parameters and marked increase of central LCs could be demonstrated in SLE patients. SLE alters not only the LC density but also the morphology, modifies corneal homeostasis, and might contribute to the development of dry eye.

  4. Radiofrequency testing of satellite segment of simulated 30/20 GHz satellite communications system

    Science.gov (United States)

    Leonard, R. F.; Kerczewski, R.

    1985-01-01

    A laboratory communications system has been developed that can serve as a test bed for the evaluation of advanced microwave (30/20 GHz) components produced under NASA technology programs. The system will ultimately permit the transmission of a stream of high-rate (220 Mbps) digital data from the originating user, through a ground terminal, through a hardware-simulated satellite, to a receiving ground station, to the receiving user. This report contains the results of radiofrequency testing of the satellite portion of that system. Data presented include output spurious responses, attainable signal-to-noise ratios, a baseline power budget, usable frequency bands, phase and amplitude response data for each of the frequency bands, and the effects of power level variation.

  5. Remote Synchronization Experiments for Quasi-Senith Satellite System Using Current Geostationary Satellites

    Directory of Open Access Journals (Sweden)

    Toshiaki Iwata

    2010-01-01

    Full Text Available The remote synchronization system for the onboard crystal oscillator (RESSOX realizes accurate synchronization between an atomic clock at a ground station and the QZSS onboard crystal oscillator, reduces overall cost and satellite power consumption, as well as onboard weight and volume, and is expected to have a longer lifetime than a system with onboard atomic clocks. Since a QZSS does not yet exist, we have been conducting synchronization experiments using geostationary earth orbit satellites (JCSAT-1B or Intelsat-4 to confirm that RESSOX is an excellent system for timing synchronization. JCSAT-1B, the elevation angle of which is 46.5 degrees at our institute, is little affected by tropospheric delay, whereas Intelsat-4, the elevation angle of which is 7.9 degrees, is significantly affected. The experimental setup and the results of uplink experiments and feedback experiments using mainly Intelsat-4 are presented. The results show that synchronization within 10 ns is realized.

  6. An eye tracking system for monitoring face scanning patterns reveals the enhancing effect of oxytocin on eye contact in common marmosets.

    Science.gov (United States)

    Kotani, Manato; Shimono, Kohei; Yoneyama, Toshihiro; Nakako, Tomokazu; Matsumoto, Kenji; Ogi, Yuji; Konoike, Naho; Nakamura, Katsuki; Ikeda, Kazuhito

    2017-09-01

    Eye tracking systems are used to investigate eyes position and gaze patterns presumed as eye contact in humans. Eye contact is a useful biomarker of social communication and known to be deficient in patients with autism spectrum disorders (ASDs). Interestingly, the same eye tracking systems have been used to directly compare face scanning patterns in some non-human primates to those in human. Thus, eye tracking is expected to be a useful translational technique for investigating not only social attention and visual interest, but also the effects of psychiatric drugs, such as oxytocin, a neuropeptide that regulates social behavior. In this study, we report on a newly established method for eye tracking in common marmosets as unique New World primates that, like humans, use eye contact as a mean of communication. Our investigation was aimed at characterizing these primates face scanning patterns and evaluating the effects of oxytocin on their eye contact behavior. We found that normal common marmosets spend more time viewing the eyes region in common marmoset's picture than the mouth region or a scrambled picture. In oxytocin experiment, the change in eyes/face ratio was significantly greater in the oxytocin group than in the vehicle group. Moreover, oxytocin-induced increase in the change in eyes/face ratio was completely blocked by the oxytocin receptor antagonist L-368,899. These results indicate that eye tracking in common marmosets may be useful for evaluating drug candidates targeting psychiatric conditions, especially ASDs. Copyright © 2017 Elsevier Ltd. All rights reserved.

  7. The principle of the positioning system based on communication satellites

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    It is a long dream to realize the communication and navigation functionality in a satellite system in the world. This paper introduces how to establish the system, a positioning system based on communication satellites called Chinese Area Positioning System (CAPS). Instead of the typical navigation satellites, the communication satellites are configured firstly to transfer navigation signals from ground stations, and can be used to obtain service of the positioning, velocity and time, and to achieve the function of navigation and positioning. Some key technique issues should be first solved; they include the accuracy position determination and orbit prediction of the communication satellites, the measur- ing and calculation of transfer time of the signals, the carrier frequency drift in communication satellite signal transfer, how to improve the geometrical configuration of the constellation in the system, and the integration of navigation & communication. Several innovative methods are developed to make the new system have full functions of navigation and communication. Based on the development of crucial techniques and methods, the CAPS demonstration system has been designed and developed. Four communication satellites in the geosynchronous orbit (GEO) located at 87.5°E, 110.5°E, 134°E, 142°E and barometric altimetry are used in the CAPS system. The GEO satellites located at 134°E and 142°E are decommissioned GEO (DGEO) satellites. C-band is used as the navigation band. Dual frequency at C1=4143.15 MHz and C2=3826.02 MHz as well as dual codes with standard code (CA code and precision code (P code)) are adopted. The ground segment consists of five ground stations; the master station is in Lintong, Xi’an. The ground stations take a lot of responsibilities, including monitor and management of the operation of all system components, determination of the satellite position and prediction of the satellite orbit, accomplishment of the virtual atomic clock

  8. Integration of satellite fire products into MPI Earth System Model

    Science.gov (United States)

    Khlystova, Iryna G.; Kloster, Silvia

    2013-04-01

    Fires are the ubiquitous phenomenon affecting all natural biomes. Since the beginning of the satellite Era, fires are being continuously observed from satellites. The most interesting satellite parameter retrieved from satellite measurements is the burned area. Combined with information on biomass available for burning the burned area can be translated into climate relevant carbon emissions from fires into the atmosphere. In this study we integrate observed burned area into a global vegetation model to derive global fire emissions. Global continuous burned area dataset is provided by the Global Fire Emissions Dataset (GFED). GFED products were obtained from MODIS (and pre-MODIS) satellites and are available for the time period of 14 years (1997-2011). This dataset is widely used, well documented and supported by periodical updates containing new features. We integrate the global burned area product into the land model JSBACH, a part of the Earth-System model developed at the Max Plank Institute for Meteorology. The land model JSBACH simulates land biomass in terms of carbon content. Fire is an important disturbance process in the Earth's carbon cycle and affects mainly the carbon stored in vegetation. In the standard JSBACH version fire is represented by process based algorithms. Using the satellite data as an alternative we are targeting better comparability of modeled carbon emissions with independent satellite measurements of atmospheric composition. The structure of burned vegetation inside of a biome can be described as the balance between woody and herbaceous vegetation. GFED provides in addition to the burned area satellite derived information of the tree cover distribution within the burned area. Using this dataset, we can attribute the burned area to the respective simulated herbaceous or woody biomass within the vegetation model. By testing several extreme cases we evaluate the quantitative impact of vegetation balance between woody and herbaceous

  9. Satellite systems for personal applications concepts and technology

    CERN Document Server

    Richharia, Madhavendra

    2010-01-01

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

  10. Design and characteristics of a multiband communication satellite antenna system

    Science.gov (United States)

    Ueno, Kenji; Itanami, Takao; Kumazawa, Hiroyuki; Ohtomo, Isao

    1995-04-01

    Feasibility studies on a multiband communication satellite antenna system and the key technologies involved in devising this system are described. The proposed multiband communication satellite utilizes four frequency bands: Ka (30/20 GHz), Ku (14/12 GHz), C (6/4 GHz), and S (2.6/2.5 GHz). It has six beam configurations, three multibeam and three shaped-beam. The following key technologies are presented: (1) a low-loss frequency selective subreflector (FSR) for compact feeds, (2) a low-loss and broadband frequency selective surface (FSS), and (3) a highly accurate and reliable mesh reflector.

  11. Improvement of orbit determination accuracy for Beidou Navigation Satellite System with Two-way Satellite Time Frequency Transfer

    Science.gov (United States)

    Tang, Chengpan; Hu, Xiaogong; Zhou, Shanshi; Guo, Rui; He, Feng; Liu, Li; Zhu, Lingfeng; Li, Xiaojie; Wu, Shan; Zhao, Gang; Yu, Yang; Cao, Yueling

    2016-10-01

    The Beidou Navigation Satellite System (BDS) manages to estimate simultaneously the orbits and clock offsets of navigation satellites, using code and carrier phase measurements of a regional network within China. The satellite clock offsets are also directly measured with Two-way Satellite Time Frequency Transfer (TWSTFT). Satellite laser ranging (SLR) residuals and comparisons with the precise ephemeris indicate that the radial error of GEO satellites is much larger than that of IGSO and MEO satellites and that the BDS orbit accuracy is worse than GPS. In order to improve the orbit determination accuracy for BDS, a new orbit determination strategy is proposed, in which the satellite clock measurements from TWSTFT are fixed as known values, and only the orbits of the satellites are solved. However, a constant systematic error at the nanosecond level can be found in the clock measurements, which is obtained and then corrected by differencing the clock measurements and the clock estimates from orbit determination. The effectiveness of the new strategy is verified by a GPS regional network orbit determination experiment. With the IGS final clock products fixed, the orbit determination and prediction accuracy for GPS satellites improve by more than 50% and the 12-h prediction User Range Error (URE) is better than 0.12 m. By processing a 25-day of measurement from the BDS regional network, an optimal strategy for the satellite-clock-fixed orbit determination is identified. User Equivalent Ranging Error is reduced by 27.6% for GEO satellites, but no apparent reduction is found for IGSO/MEO satellites. The SLR residuals exhibit reductions by 59% and 32% for IGSO satellites but no reductions for GEO and MEO satellites.

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

    Science.gov (United States)

    Anderson, R. E.

    1979-01-01

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

  13. The principle of the positioning system based on communication satellites

    Institute of Scientific and Technical Information of China (English)

    AI GuoXiang; SHI HuLi; WU HaiTao; LI ZhiGang; GUO Ji

    2009-01-01

    It is a long dream to realize the communication and navigation functionality in a satellite system in the world.This paper introduces how to establish the system,a positioning system based on communication satellites called Chinese Area Positioning System (CAPS).Instead of the typical navigation satelIites,the communication satellites are configured firstly to transfer navigation signals from ground stations,and can be used to obtain service of the positioning,velocity and time,and to achieve the function of navigation and positioning.Some key technique issues should be first solved; they include the accuracy position determination and orbit prediction of the communication satellites,the measuring and calculation of transfer time of the signals,the carrier frequency drift in communication satellite ignal transfer,how to improve the geometrical configuration of the constellation in the system,and the integration of navigation & communication.Several innovative methods are developed to make the new system have full functions of navigation and communication.Based on the development of crucial techniques and methods,the CAPS demonstration system has been designed and developed.Four communication satellites in the geosynchronous orbit (GEO) located at 87.5°E,110.5°E,134°E,142°E and barometric altimetry are used in the CAPS system.The GEO satellites located at 134°E and 142°E re decommissioned GEO (DGEO) satellites.C-band is used as the navigation band.Dual frequency at C1=4143.15 MHz and C2=3826.02 MHz as well as dual codes with standard code (CA code and precision code (P code)) are adopted.The ground segment consists of five ground stations; the master station is in Lintong,Xi'an.The ground stations take a lot of responsibilities,including monitor and management of the operation of all system components,determination of the satellite position and prediction of the satellite orbit,accomplishment of the virtual atomic clock measurement,transmission and receiving

  14. An Orbiting Standards Platform for communication satellite system RF measurements

    Science.gov (United States)

    Wallace, R. G.; Woodruff, J. J.

    1978-01-01

    The Orbiting Standards Platform (OSP) is a proposed satellite dedicated to performing RF measurements on space communications systems. It would consist of a quasi-geostationary spacecraft containing an ensemble of calibrated RF sources and field strength meters operating in several microwave bands, and would be capable of accurately and conveniently measuring critical earth station and satellite RF performance parameters, such as EIRP, gain, figure of merit (G/T), crosspolarization, beamwidth, and sidelobe levels. The feasibility and utility of the OSP concept has been under joint study by NASA, NBS, Comsat and NTIA. A survey of potential OSP users was conducted by NTIA as part of this effort. The response to this survey, along with certain trends in satellite communications system design, indicates a growing need for such a measurement service.

  15. Eagle i-Bot: An Eye-controlled System

    Directory of Open Access Journals (Sweden)

    Onindita Afrin

    2013-01-01

    Full Text Available Hundreds of millions of people in the world are hand impaired in some way, and for many, there is no absolute solution. Operation of computers by physically disabled people; especially with hand impairment was quite impossible till now because use of hands plays a vital role in the use of mouse, touch pad and keyboard. We proposed a new system named as “Eagle i-Bot - An eye-controlled system” which has come with a feasible solution for this scenario. With this system, computers and robots can be controlled by the pair of eyes’ movement or iris movement and voice commands control all the mouse events. This system works with image processing system based on Voila-Jones algorithm and modified Ada-boost algorithms along with java robot class and sphinx-4 frameworks. In this paper, this system is described including software and hardware aspects, algorithms that are used and scopes where Eagle i-Bot can be used.

  16. Edge Detection Model Based on Involuntary Eye Movements of the Eye-Retina System

    Directory of Open Access Journals (Sweden)

    András Róka

    2007-03-01

    Full Text Available Traditional edge-detection algorithms in image processing typically convolute afilter operator and the input image, and then map overlapping input image regions tooutput signals. Convolution also serves as a basis in biologically inspired (Sobel, Laplace,Canny algorithms. Recent results in cognitive retinal research have shown that ganglioncell receptive fields cover the mammalian retina in a mosaic arrangement, withinsignificant amounts of overlap in the central fovea. This means that the biologicalrelevance of traditional and widely adapted edge-detection algorithms with convolutionbasedoverlapping operator architectures has been disproved. However, using traditionalfilters with non-overlapping operator architectures leads to considerable losses in contourinformation. This paper introduces a novel, tremor-based retina model and edge-detectionalgorithm that reconciles these differences between the physiology of the retina and theoverlapping architectures used by today's widely adapted algorithms. The algorithm takesinto consideration data convergence, as well as the dynamic properties of the retina, byincorporating a model of involuntary eye tremors and the impulse responses of ganglioncells. Based on the evaluation of the model, two hypotheses are formulated on the highlydebated role of involuntary eye tremors: 1 The role of involuntary eye tremors hasinformation theoretical implications 2 From an information processing point of view, thefunctional role of involuntary eye-movements extends to more than just the maintenance ofaction potentials. Involuntary eye-movements may be responsible for the compensation ofinformation losses caused by a non-overlapping receptive field architecture. In support ofthese hypotheses, the article provides a detailed analysis of the model's biologicalrelevance, along with numerical simulations and a hardware implementation.

  17. Algorithms for High-Speed Noninvasive Eye-Tracking System

    Science.gov (United States)

    Talukder, Ashit; Morookian, John-Michael; Lambert, James

    2010-01-01

    Two image-data-processing algorithms are essential to the successful operation of a system of electronic hardware and software that noninvasively tracks the direction of a person s gaze in real time. The system was described in High-Speed Noninvasive Eye-Tracking System (NPO-30700) NASA Tech Briefs, Vol. 31, No. 8 (August 2007), page 51. To recapitulate from the cited article: Like prior commercial noninvasive eyetracking systems, this system is based on (1) illumination of an eye by a low-power infrared light-emitting diode (LED); (2) acquisition of video images of the pupil, iris, and cornea in the reflected infrared light; (3) digitization of the images; and (4) processing the digital image data to determine the direction of gaze from the centroids of the pupil and cornea in the images. Most of the prior commercial noninvasive eyetracking systems rely on standard video cameras, which operate at frame rates of about 30 Hz. Such systems are limited to slow, full-frame operation. The video camera in the present system includes a charge-coupled-device (CCD) image detector plus electronic circuitry capable of implementing an advanced control scheme that effects readout from a small region of interest (ROI), or subwindow, of the full image. Inasmuch as the image features of interest (the cornea and pupil) typically occupy a small part of the camera frame, this ROI capability can be exploited to determine the direction of gaze at a high frame rate by reading out from the ROI that contains the cornea and pupil (but not from the rest of the image) repeatedly. One of the present algorithms exploits the ROI capability. The algorithm takes horizontal row slices and takes advantage of the symmetry of the pupil and cornea circles and of the gray-scale contrasts of the pupil and cornea with respect to other parts of the eye. The algorithm determines which horizontal image slices contain the pupil and cornea, and, on each valid slice, the end coordinates of the pupil and cornea

  18. Testing a satellite automatic nutation control system. [on synchronous meteorological satellite

    Science.gov (United States)

    Hrasiar, J. A.

    1974-01-01

    Testing of a particular nutation control system for the synchronous meteorological satellite (SMS) is described. The test method and principles are applicable to nutation angle control for other satellites with similar requirements. During its ascent to synchronous orbit, a spacecraft like the SMS spins about its minimum-moment-of-inertia axis. An uncontrolled spacecraft in this state is unstable because torques due to fuel motion increase the nutation angle. However, the SMS is equipped with an automatic nutation control (ANC) system which will keep the nutation angle close to zero. Because correct operation of this system is critical to mission success, it was tested on an air-bearing table. The ANC system was mounted on the three-axis air-bearing table which was scaled to the SMS and equipped with appropriate sensors and thrusters. The table was spun up in an altitude chamber and nutation induced so that table motion simulated spacecraft motion. The ANC system was used to reduce the nutation angle. This dynamic test of the ANC system met all its objectives and provided confidence that the ANC system will control the SMS nutation angle.

  19. Origin of the Different Architectures of the Jovian and Saturnian Satellite Systems

    OpenAIRE

    Sasaki, Takanori; Stewart, Glen R.; Ida, Shigeru

    2010-01-01

    The Jovian regular satellite system mainly consists of four Galilean satellites that have similar masses and are trapped in mutual mean motion resonances except for the outer satellite, Callisto. On the other hand, the Saturnian regular satellite system has only one big icy body, Titan, and a population of much smaller icy moons. We have investigated the origin of these major differences between the Jovian and Saturnian satellite systems by semi-analytically simulating the growth and orbital ...

  20. Multi-agent robotic systems and applications for satellite missions

    Science.gov (United States)

    Nunes, Miguel A.

    A revolution in the space sector is happening. It is expected that in the next decade there will be more satellites launched than in the previous sixty years of space exploration. Major challenges are associated with this growth of space assets such as the autonomy and management of large groups of satellites, in particular with small satellites. There are two main objectives for this work. First, a flexible and distributed software architecture is presented to expand the possibilities of spacecraft autonomy and in particular autonomous motion in attitude and position. The approach taken is based on the concept of distributed software agents, also referred to as multi-agent robotic system. Agents are defined as software programs that are social, reactive and proactive to autonomously maximize the chances of achieving the set goals. Part of the work is to demonstrate that a multi-agent robotic system is a feasible approach for different problems of autonomy such as satellite attitude determination and control and autonomous rendezvous and docking. The second main objective is to develop a method to optimize multi-satellite configurations in space, also known as satellite constellations. This automated method generates new optimal mega-constellations designs for Earth observations and fast revisit times on large ground areas. The optimal satellite constellation can be used by researchers as the baseline for new missions. The first contribution of this work is the development of a new multi-agent robotic system for distributing the attitude determination and control subsystem for HiakaSat. The multi-agent robotic system is implemented and tested on the satellite hardware-in-the-loop testbed that simulates a representative space environment. The results show that the newly proposed system for this particular case achieves an equivalent control performance when compared to the monolithic implementation. In terms on computational efficiency it is found that the multi

  1. The international maritime satellite communications system INMARSAT (Handbook)

    Science.gov (United States)

    Zhilin, Viktor A.

    The organization and services provided by the INMARSAT satellite communications system are summarized. The structure and operation of the system are described with reference to transmission line parameters, frequency assignment, signals, telex communications, electrical parameters of communication channels, modulation, synchronization, and methods of protection against errors in the transmission of discrete messages. The discussion also covers the principal components of the INMARSAT system and the operation of ship-based stations.

  2. A Fault tolerant Control Supervisory System development Procedurefor Small Satellites

    DEFF Research Database (Denmark)

    Izadi-Zamanabadi, Roozbeh; Larsen, Jesper Abildgaard

    The paper presents a stepwise procedure to develop a fault tolerant control system for small satellites. The procedure is illustrated through implementation on the AAUSAT-II spacecraft. As it is shown the presented procedure requires expertise from several disciplines that are nevertheless...

  3. Internal Calibration of HJ-1-C Satellite SAR System

    Directory of Open Access Journals (Sweden)

    Yang Zhen

    2014-06-01

    Full Text Available The HJ-1-C satellite is a Synthetic Aperture Radar (SAR satellite of a small constellation for environmental and disaster monitoring. At present, it is in orbit and working well. The SAR system uses a mesh reflector antenna and centralized power amplifier, and has an internal calibration function in orbit. This study introduces the internal calibration modes and signal paths. The design and realization of the internal calibrator are discussed in detail. Finally, the internal calibration data acquired in orbit are also analyzed.

  4. Multi-spectral band selection for satellite-based systems

    Energy Technology Data Exchange (ETDEWEB)

    Clodius, W.B.; Weber, P.G.; Borel, C.C.; Smith, B.W.

    1998-09-01

    The design of satellite based multispectral imaging systems requires the consideration of a number of tradeoffs between cost and performance. The authors have recently been involved in the design and evaluation of a satellite based multispectral sensor operating from the visible through the long wavelength IR. The criteria that led to some of the proposed designs and the modeling used to evaluate and fine tune the designs will both be discussed. These criteria emphasized the use of bands for surface temperature retrieval and the correction of atmospheric effects. The impact of cost estimate changes on the final design will also be discussed.

  5. Search and rescue satellite-aided tracking system

    Science.gov (United States)

    Trudell, B.; Gutwein, J. M.; Vollmers, R.; Wammer, D.

    1980-10-01

    The objective of Sarsat is to demonstrate that satellites can greatly facilitate the monitoring, detection, and location of distress incidents alerted by Emergency Locator Transmitters (ELTs) and Emergency Position Indicating Radio Beacons (EPIRBs) carried on commercial, military, and general aviation aircraft and some marine vessels. The detection and location will be accomplished by relaying, via satellite, ELT/EPIRB distress information to ground stations, which will complete the data processing and forward alert and position location data to rescue coordination services. This paper presents a Sarsat system description and a summary of Coast Guard and USAF objectives for the initial demonstration and evaluation tests of Sarsat.

  6. An interactive system for compositing digital radar and satellite data

    Science.gov (United States)

    Heymsfield, G. M.; Ghosh, K. K.; Chen, L. C.

    1983-01-01

    This paper describes an approach for compositing digital radar data and GOES satellite data for meteorological analysis. The processing is performed on a user-oriented image processing system, and is designed to be used in the research mode. It has a capability to construct PPIs and three-dimensional CAPPIs using conventional as well as Doppler data, and to composite other types of data. In the remapping of radar data to satellite coordinates, two steps are necessary. First, PPI or CAPPI images are remapped onto a latitude-longitude projection. Then, the radar data are projected into satellite coordinates. The exact spherical trigonometric equations, and the approximations derived for simplifying the computations are given. The use of these approximations appears justified for most meteorological applications. The largest errors in the remapping procedure result from the satellite viewing angle parallax, which varies according to the cloud top height. The horizontal positional error due to this is of the order of the error in the assumed cloud height in mid-latitudes. Examples of PPI and CAPPI data composited with satellite data are given for Hurricane Frederic on 13 September 1979 and for a squall line on 2 May 1979 in Oklahoma.

  7. Sensor system for Greenhouse Gas Observing Satellite (GOSAT)

    Science.gov (United States)

    Hamazaki, Takashi; Kuze, Akihiko; Kondo, Kayoko

    2004-11-01

    Global warming has become a very serious issue for human beings. In 1997, the Kyoto Protocol was adopted at the Third Session of the Conference of the Parties to the United Nations Framework Convention on Climate Change (COP3), making it mandatory for developed nations to reduce carbon dioxide emissions by six (6) to eight (8) per cent of their total emissions in 1990, and to meet this goal sometime between 2008 and 2012. The Greenhouse gases Observing SATellite (GOSAT) is design to monitor the global distribution of carbon dioxide (CO2) from orbit. GOSAT is a joint project of Japan Aerospace Exploration Agency (JAXA), the Ministry of Environment (MOE), and the National Institute for Environmental Studies (NIES). JAXA is responsible for the satellite and instrument development, MOE is involved in the instrument development, and NIES is responsible for the satellite data retrieval. The satellite is scheduled to be launched in 2008. In order to detect the CO2 variation of boundary layers, both the technique to measure the column density and the retrieval algorithm to remove cloud and aerosol contamination are investigated. Main mission sensor of the GOSAT is a Fourier Transform Spectrometer with high optical throughput, spectral resolution and wide spectral coverage, and a cloud-aerosol detecting imager attached to the satellite. The paper presents the mission sensor system of the GOSAT together with the results of performance demonstration with proto-type instrument aboard an aircraft.

  8. Design of Customizable Automated Low Cost Eye Testing System

    OpenAIRE

    2014-01-01

    Background and Objectives: In many underdeveloped and third world countries, eye care is often neglected due to illiteracy. Particularly people in rural areas suffer with eye problems due to mal nutrition. The government is spending lot of money and efforts in screening the people at periodic intervals. One of the challenges faced by the doctors is screening the school children.

  9. Eye-safe lidar system for pesticide spray drift measurement.

    Science.gov (United States)

    Gregorio, Eduard; Rocadenbosch, Francesc; Sanz, Ricardo; Rosell-Polo, Joan R

    2015-02-04

    Spray drift is one of the main sources of pesticide contamination. For this reason, an accurate understanding of this phenomenon is necessary in order to limit its effects. Nowadays, spray drift is usually studied by using in situ collectors which only allow time-integrated sampling of specific points of the pesticide clouds. Previous research has demonstrated that the light detection and ranging (lidar) technique can be an alternative for spray drift monitoring. This technique enables remote measurement of pesticide clouds with high temporal and distance resolution. Despite these advantages, the fact that no lidar instrument suitable for such an application is presently available has appreciably limited its practical use. This work presents the first eye-safe lidar system specifically designed for the monitoring of pesticide clouds. Parameter design of this system is carried out via signal-to-noise ratio simulations. The instrument is based on a 3-mJ pulse-energy erbium-doped glass laser, an 80-mm diameter telescope, an APD optoelectronic receiver and optomechanically adjustable components. In first test measurements, the lidar system has been able to measure a topographic target located over 2 km away. The instrument has also been used in spray drift studies, demonstrating its capability to monitor the temporal and distance evolution of several pesticide clouds emitted by air-assisted sprayers at distances between 50 and 100 m.

  10. Accuracy Performance Evaluation of Beidou Navigation Satellite System

    Science.gov (United States)

    Wang, W.; Hu, Y. N.

    2017-03-01

    Accuracy is one of the key elements of the regional Beidou Navigation Satellite System (BDS) performance standard. In this paper, we review the definition specification and evaluation standard of the BDS accuracy. Current accuracy of the regional BDS is analyzed through the ground measurements and compared with GPS in terms of dilution of precision (DOP), signal-in-space user range error (SIS URE), and positioning accuracy. The Positioning DOP (PDOP) map of BDS around Chinese mainland is compared with that of GPS. The GPS PDOP is between 1.0-2.0 and does not vary with the user latitude and longitude, while the BDS PDOP varies between 1.5-5.0, and increases as the user latitude increases, and as the user longitude apart from 118°. The accuracies of the broadcast orbits of BDS are assessed by taking the precise orbits from International GNSS Service (IGS) as the reference, and by making satellite laser ranging (SLR) residuals. The radial errors of the BDS inclined geosynchronous orbit (IGSO) and medium orbit (MEO) satellites broadcast orbits are at the 0.5m level, which are larger than those of GPS satellites at the 0.2m level. The SLR residuals of geosynchronous orbit (GEO) satellites are 65.0cm, which are larger than those of IGSO, and MEO satellites, at the 50.0cm level. The accuracy of broadcast clock offset parameters of BDS is computed by taking the clock measurements of Two-way Satellite Radio Time Frequency Transfer as the reference. Affected by the age of broadcast clock parameters, the error of the broadcast clock offset parameters of the MEO satellites is the largest, at the 0.80m level. Finally, measurements of the multi-GNSS (MGEX) receivers are used for positioning accuracy assessment of BDS and GPS. It is concluded that the positioning accuracy of regional BDS is better than 10m at the horizontal component and the vertical component. The combined positioning accuracy of both systems is better than one specific system.

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

    Science.gov (United States)

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

    1995-01-01

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

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

    Science.gov (United States)

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

    2001-01-01

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

  13. Cyber security with radio frequency interferences mitigation study for satellite systems

    Science.gov (United States)

    Wang, Gang; Wei, Sixiao; Chen, Genshe; Tian, Xin; Shen, Dan; Pham, Khanh; Nguyen, Tien M.; Blasch, Erik

    2016-05-01

    Satellite systems including the Global Navigation Satellite System (GNSS) and the satellite communications (SATCOM) system provide great convenience and utility to human life including emergency response, wide area efficient communications, and effective transportation. Elements of satellite systems incorporate technologies such as navigation with the global positioning system (GPS), satellite digital video broadcasting, and information transmission with a very small aperture terminal (VSAT), etc. The satellite systems importance is growing in prominence with end users' requirement for globally high data rate transmissions; the cost reduction of launching satellites; development of smaller sized satellites including cubesat, nanosat, picosat, and femtosat; and integrating internet services with satellite networks. However, with the promising benefits, challenges remain to fully develop secure and robust satellite systems with pervasive computing and communications. In this paper, we investigate both cyber security and radio frequency (RF) interferences mitigation for satellite systems, and demonstrate that they are not isolated. The action space for both cyber security and RF interferences are firstly summarized for satellite systems, based on which the mitigation schemes for both cyber security and RF interferences are given. A multi-layered satellite systems structure is provided with cross-layer design considering multi-path routing and channel coding, to provide great security and diversity gains for secure and robust satellite systems.

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

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2000-03-01

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

  15. Satellite Power Systems (SPS) concept definition study. Volume 5: Special emphasis studies. [rectenna and solar power satellite design studies

    Science.gov (United States)

    Hanley, G. M.

    1980-01-01

    Satellite configurations based on the Satellite Power System baseline requirements were analyzed and a preferred concept selected. A satellite construction base was defined, precursor operations incident to establishment of orbital support facilities identified, and the satellite construction sequence and procedures developed. Rectenna construction requirement were also addressed. Mass flow to orbit requirements were revised and traffic models established based on construction of 60 instead of 120 satellites. Analyses were conducted to determine satellite control, resources, manufacturing, and propellant requirements. The impact of the laser beam used for space-to-Earth power transmission upon the intervening atmosphere was examined as well as the inverse effect. The significant space environments and their effects on spacecraft components were investigated to define the design and operational limits imposed by the environments on an orbit transfer vehicle. The results show that LEO altitude 300 nmi and transfer orbit duration 6 months are preferrable.

  16. Eye-safe projection system with flexible architecture

    Science.gov (United States)

    Sabirov, Viacheslav

    2014-03-01

    Nowadays multimedia projectors of various types are widely used in many areas of human life. Significant part of all projector devices are used in two main areas: education (e. g. on lectures) and business (e. g. on all sorts of meetings). What makes projector a demanded device? It provides a user with high quality full color large diagonal image for a much lower price than display devices that based on other popular non-projecting technologies. However the absolute majority of projectors share a significant disadvantage. If human steps into the beam two major negative effects appear: a distorted image appears on human's body and human's eyes become glared by bright light. The first effect is undesirable by the audience and the second effect is undesirable by the presenter. To avoid the abovementioned effects short throw projectors can be used but they are more expensive than regular ones and have significant limitations on the placement spot: usually the lens of a short-throw projector is designed so that it has to be placed on a fixed distance to the screen. We propose a different solution of similar problem: instead of moving the projector towards the screen let us black out the human (or other obstacle) from it. To do so our system must know the exact position of human. In this paper we propose a system with flexible architecture that realizes the above-mentioned solution.

  17. The MUSES Satellite Team and Multidisciplinary System Engineering

    Science.gov (United States)

    Chen, John C.; Paiz, Alfred R.; Young, Donald L.

    1997-01-01

    In a unique partnership between three minority-serving institutions and NASA's Jet Propulsion Laboratory, a new course sequence, including a multidisciplinary capstone design experience, is to be developed and implemented at each of the schools with the ambitious goal of designing, constructing and launching a low-orbit Earth-resources satellite. The three universities involved are North Carolina A&T State University (NCA&T), University of Texas, El Paso (UTEP), and California State University, Los Angeles (CSULA). The schools form a consortium collectively known as MUSES - Minority Universities System Engineering and Satellite. Four aspects of this project make it unique: (1) Including all engineering disciplines in the capstone design course, (2) designing, building and launching an Earth-resources satellite, (3) sustaining the partnership between the three schools to achieve this goal, and (4) implementing systems engineering pedagogy at each of the three schools. This paper will describe the partnership and its goals, the first design of the satellite, the courses developed at NCA&T, and the implementation plan for the course sequence.

  18. Spatial heterogeneity in mangroves assessed by GeoEye-1 satellite data: a case-study in Zhanjiang Mangrove National Nature Reserve (ZMNNR), China

    Science.gov (United States)

    Leempoel, K.; Bourgeois, C.; Zhang, J.; Wang, J.; Chen, M.; Satyaranayana, B.; Bogaert, J.; Dahdouh-Guebas, F.

    2013-02-01

    Mangrove forests, which are declining across the globe mainly because of human intervention, require an evaluation of their past and present status (e.g. areal extent, species-level distribution, etc.) to better implement conservation and management strategies. In this paper, mangrove cover dynamics at Gaoqiao (under the jurisdiction of Zhanjiang Mangrove National Nature Reserve - ZMNNR, P. R. China) were assessed through time using 1967 (Corona KH-4B), 2000 (Landsat ETM+), and 2009 (GeoEye-1) satellite imagery. An important decline in mangrove cover (-36%) was observed between 1967 and 2009 due to dike construction for agriculture (paddy) and aquaculture practices. Moreover, dike construction prevented mangroves from expanding landward. Although a small increase of mangrove area was observed between 2000 and 2009 (+24%), the ratio mangrove/aquaculture kept decreasing due to increased aquaculture at the expense of rice culture. In the land-use/cover map based on ground-truth data (5 m × 5 m plot-based tree measurements) (August-September, 2009) and spectral reflectance values (obtained from pansharpened GeoEye-1), both Bruguiera gymnorrhiza and small Aegiceras corniculatum are distinguishable at 73-100% accuracy, whereas tall A. corniculatum is identifiable at only 53% due to its mixed vegetation stands close to B. gymnorrhiza (classification accuracy: 85%). Sand proportion in the sediment showed significant differences (Kruskal-Wallis/ANOVA, P changes. Overall, the advantage of very high resolution satellite images like GeoEye-1 for mangrove spatial heterogeneity assessment and/or species-level discrimination is well demonstrated, along with the complexity to provide a precise classification for non-dominant species (e.g. Kandelia obovata) at Gaoqiao. Despite the limitations such as geometric distortion and single band information, the 42-yr old Corona declassified images are invaluable for land-use/cover change detections when compared to recent satellite data

  19. Satellite Imagery Assisted Road-Based Visual Navigation System

    Science.gov (United States)

    Volkova, A.; Gibbens, P. W.

    2016-06-01

    There is a growing demand for unmanned aerial systems as autonomous surveillance, exploration and remote sensing solutions. Among the key concerns for robust operation of these systems is the need to reliably navigate the environment without reliance on global navigation satellite system (GNSS). This is of particular concern in Defence circles, but is also a major safety issue for commercial operations. In these circumstances, the aircraft needs to navigate relying only on information from on-board passive sensors such as digital cameras. An autonomous feature-based visual system presented in this work offers a novel integral approach to the modelling and registration of visual features that responds to the specific needs of the navigation system. It detects visual features from Google Earth* build a feature database. The same algorithm then detects features in an on-board cameras video stream. On one level this serves to localise the vehicle relative to the environment using Simultaneous Localisation and Mapping (SLAM). On a second level it correlates them with the database to localise the vehicle with respect to the inertial frame. The performance of the presented visual navigation system was compared using the satellite imagery from different years. Based on comparison results, an analysis of the effects of seasonal, structural and qualitative changes of the imagery source on the performance of the navigation algorithm is presented. * The algorithm is independent of the source of satellite imagery and another provider can be used

  20. Interoperability of satellite-based augmentation systems for aircraft navigation

    Science.gov (United States)

    Dai, Donghai

    The Federal Aviation Administration (FAA) is pioneering a transformation of the national airspace system from its present ground based navigation and landing systems to a satellite based system using the Global Positioning System (GPS). To meet the critical safety-of-life aviation positioning requirements, a Satellite-Based Augmentation System (SBAS), the Wide Area Augmentation System (WAAS), is being implemented to support navigation for all phases of flight, including Category I precision approach. The system is designed to be used as a primary means of navigation, capable of meeting the Required Navigation Performance (RNP), and therefore must satisfy the accuracy, integrity, continuity and availability requirements. In recent years there has been international acceptance of Global Navigation Satellite Systems (GNSS), spurring widespread growth in the independent development of SBASs. Besides the FAA's WAAS, the European Geostationary Navigation Overlay Service System (EGNOS) and the Japan Civil Aviation Bureau's MTSAT-Satellite Augmentation System (MSAS) are also being actively developed. Although all of these SBASs can operate as stand-alone, regional systems, there is increasing interest in linking these SBASs together to reduce costs while improving service coverage. This research investigated the coverage and availability improvements due to cooperative efforts among regional SBAS networks. The primary goal was to identify the optimal interoperation strategies in terms of performance, complexity and practicality. The core algorithms associated with the most promising concepts were developed and demonstrated. Experimental verification of the most promising concepts was conducted using data collected from a joint international test between the National Satellite Test Bed (NSTB) and the EGNOS System Test Bed (ESTB). This research clearly shows that a simple switch between SBASs made by the airborne equipment is the most effective choice for achieving the

  1. Automatic charge control system for satellites

    Science.gov (United States)

    Shuman, B. M.; Cohen, H. A.

    1985-01-01

    The SCATHA and the ATS-5 and 6 spacecraft provided insights to the problem of spacecraft charging at geosychronous altitudes. Reduction of the levels of both absolute and differential charging was indicated, by the emission of low energy neutral plasma. It is appropriate to complete the transition from experimental results to the development of a system that will sense the state-of-charge of a spacecraft, and, when a predetermined threshold is reached, will respond automatically to reduce it. A development program was initiated utilizing sensors comparable to the proton electrostatic analyzer, the surface potential monitor, and the transient pulse monitor that flew in SCATHA, and combine these outputs through a microprocessor controller to operate a rapid-start, low energy plasma source.

  2. A Reusable Software Architecture for Small Satellite AOCS Systems

    DEFF Research Database (Denmark)

    Alminde, Lars; Bendtsen, Jan Dimon; Laursen, Karl Kaas

    2006-01-01

    with both hardware and on-board software. Some of the key issues addressed by the framework are automatic translation of mathematical specifications of hybrid systems into executable software entities, management of execution of coupled models in a parallel distributed environment, as well as interaction......This paper concerns the software architecture called Sophy, which is an abbreviation for Simulation, Observation, and Planning in HYbrid systems. We present a framework that allows execution of hybrid dynamical systems in an on-line distributed computing environment, which includes interaction...... with external components, hardware and/or software, through generic interfaces. Sophy is primarily intended as a tool for development of model based reusable software for the control and autonomous functions of satellites and/or satellite clusters....

  3. Gravimetry, Relativity, and the Global Navigation Satellite Systems

    CERN Document Server

    Tarantola, Albert; Pozo, Jose Maria; Coll, Bartolome

    2009-01-01

    Relativity is an integral part of positioning systems, and this is taken into account in today's practice by applying many "relativistic corrections" to computations performed using concepts borrowed from Galilean physics. A different, fully relativistic paradigm can be developed for operating a positioning system. This implies some fundamental changes. For instance, the basic coordinates are four times (with a symmetric meaning, not three space coordinate and one time coordinate) and the satellites must have cross-link capabilities. Gravitation must, of course, be taken into account, but not using the Newtonian theory: the gravitation field is, and only is, the space-time metric. This implies that the positioning problem and the gravimetry problem can not be separated. An optimization theory can be developed that, because it is fully relativistic, does not contain any "relativistic correction". We suggest that all positioning satellite systems should be operated in this way. The first benefit of doing so wou...

  4. Analysis of satellite broadcasting systems for digital television

    Science.gov (United States)

    de Gaudenzi, Riccardo; Elia, Carlo; Viola, Roberto

    1993-01-01

    This paper introduces the new concept of digital direct satellite broadcasting (D-DBS), which allows unprecedented flexibility by providing a large number of audio-visual services. The concept elaborated on in this paper assumes an information rate of about 40 Mb/s, which is compatible with practically all present-day transponders. After discussion of the general system concept, the optimization procedure is introduced and results of the transmission system optimization are presented. Channel distortion and uplink/downlink interference effects are taken into account by means of a time domain system computer simulation approach. It is shown, by means of link budget analysis, how a medium power direct-to-home TV satellite can provide multimedia services to users equipped with small (60 cm) dish antennas.

  5. An active attitude control system for a drag sail satellite

    Science.gov (United States)

    Steyn, Willem Herman; Jordaan, Hendrik Willem

    2016-11-01

    The paper describes the development and simulation results of a full ADCS subsystem for the deOrbitSail drag sail mission. The deOrbitSail satellite was developed as part of an European FP7 collaboration research project. The satellite was launched and commissioning started on 10th July 2015. Various new actuators and sensors designed for this mission will be presented. The deOrbitSail satellite is a 3U CubeSat to deploy a 4 by 4 m drag sail from an initial 650 km circular polar low earth orbit. With an active attitude control system it will be shown that by maximising the drag force, the expected de-orbiting period from the initial altitude will be less than 50 days. A future application of this technology will be the use of small drag sails as low-cost devices to de-orbit LEO satellites, when they have reached their end of life, without having to use expensive propulsion systems. Simulation and Hardware-in-Loop experiments proved the feasibility of the proposed attitude control system. A magnetic-only control approach using a Y-Thomson spin, is used to detumble the 3U Cubesat with stowed sail and subsequently to 3-axis stabilise the satellite to be ready for the final deployment phase. Minituarised torquer rods, a nano-sized momentum wheel, attitude sensor hardware (magnetometer, sun, earth) developed for this phase will be presented. The final phase will be to deploy and 3-axis stabilise the drag sail normal to the satellite's velocity vector, using a combined Y-momentum wheel and magnetic controller. The design and performance improvements when using a 2-axis translation stage to adjust the sail centre-of-pressure to satellite centre-of-mass offset, will also be discussed, although for launch risk reasons this stage was not included in the final flight configuration. To accurately determine the drag sail's attitude during the sunlit part of the orbit, an accurate wide field of view dual sensor to measure both the sun and nadir vector direction was developed for

  6. Tolerance analysis of cross-eye jamming systems

    CSIR Research Space (South Africa)

    Du Plessis, WP

    2010-01-01

    Full Text Available The matching required between the two directions through a retrodirective cross-eye jammer is considered using both the traditional phase-front analysis and an extended analysis. The design parameters to achieve a specified tracking error...

  7. Space Weathering on Icy Satellites in the Outer Solar System

    Science.gov (United States)

    Clark, R. N.; Perlman, Z.; Pearson, N.; Cruikshank, D. P.

    2014-01-01

    Space weathering produces well-known optical effects in silicate minerals in the inner Solar System, for example, on the Moon. Space weathering from solar wind and UV (ultraviolet radiation) is expected to be significantly weaker in the outer Solar System simply because intensities are low. However, cosmic rays and micrometeoroid bombardment would be similar to first order. That, combined with the much higher volatility of icy surfaces means there is the potential for space weathering on icy outer Solar System surfaces to show optical effects. The Cassini spacecraft orbiting Saturn is providing evidence for space weathering on icy bodies. The Cassini Visible and Infrared Mapping Spectrometer (VIMS) instrument has spatially mapped satellite surfaces and the rings from 0.35-5 microns and the Ultraviolet Imaging Spectrograph (UVIS) instrument from 0.1 to 0.2 microns. These data have sampled a complex mixing space between H2O ice and non-ice components and they show some common spectral properties. Similarly, spectra of the icy Galilean satellites and satellites in the Uranian system have some commonality in spectral properties with those in the Saturn system. The UV absorber is spectrally similar on many surfaces. VIMS has identified CO2, H2 and trace organics in varying abundances on Saturn's satellites. We postulate that through the spatial relationships of some of these compounds that they are created and destroyed through space weathering effects. For example, the trapped H2 and CO2 observed by VIMS in regions with high concentrations of dark material may in part be space weathering products from the destruction of H2O and organic molecules. The dark material, particularly on Iapetus which has the highest concentration in the Saturn system, is well matched by space-weathered silicates in the .4 to 2.6 micron range, and the spectral shapes closely match those of the most mature lunar soils, another indicator of space weathered material.

  8. The European Satellite Navigation System Galileo

    Institute of Scientific and Technical Information of China (English)

    G.W. Hein; T. Pany

    2003-01-01

    This paper starts with a brief discussion of the Galileo project status and with a description of the present Galileo architecture (space segment, ground segment, user segment). It focuses on explaining special features compared to the American GPS system. The presentation of the user segment comprises a discussion of the actual Galileo signal structure. The Galileo carrier frequency, modulation scheme and data rate of all 10 navigation signals are described as well as parameters of the search and rescue service. The navigation signals are used to realize three types of open services, the safety of life service, two types of commercial services and the public regulated service. The signal performance in terms of the pseudorange code error due to thermal noise and multipath is discussed as well as interference to and from other radionavigation services broadcasting in the E5 and E6 frequency band. The interoperability and compatibility of Galileo and GPS is realized by a properly chosen signal structures in E5a/L5 and E2-L1-E1 and compatible geodetic and time reference frames. Some new results on reciprocal GPS/Galileo signal degradation due to signal overlay are presented as well as basic requirements on the Galileo code sequences.

  9. Broadly Applicable Nanowafer Drug Delivery System for Treating Eye Injuries

    Science.gov (United States)

    2016-09-01

    255. Pixels within the threshold region were then counted using the Measure subroutine for all planes in the image stack to record the crystal volume...collected at hourly time intervals. Tear samples from Cys-NW treated eyes contained measurable levels of Cys for up to 2 h and was not detectable in the third...resulting in extremely low bioavailability. For this reason, topical Cys eye drops must be administered several times in a day to achieve a measurable

  10. Autonomous Attitude Determination and Control System for the Ørsted Satellite

    DEFF Research Database (Denmark)

    Bak, Thomas; Wisniewski, Rafal; Blanke, M.

    1996-01-01

    The Ørsted Satellite mission imposes comparatively high requirements on autonomy of the attitude control system.......The Ørsted Satellite mission imposes comparatively high requirements on autonomy of the attitude control system....

  11. Effectiveness of Technolas torsional eye tracking system on visual outcomes after photorefractive keratectomy.

    Science.gov (United States)

    Gharaee, Hamid; Ghanavati, Siamak Zaree; Rad, Saeed Shokoohi; Omidtabrizi, Arash; Naseri, Hashem

    2015-01-01

    To investigate the efficacy of Technolas 217Z eye tracking system (torsional component) in corneal surface irregularity and high order aberrations (HOAs) after photorefractive keratectomy. Patients with compound myopic astigmatism among persons demanding refractive surgery in Khatam-al-Anbia Eye Hospital with the mean age of 29 years were enrolled in this double-blind randomized interventional study. The mean spherical equivalent (SE) of refractive error was -4.75 diopters(D) (range: -1.5 to -7.0), and the mean astigmatism was 3 D (range:1.0-4). Many studies were performed for each patient including: A complete eye examination, visual acuity and Monocular contrast sensitivity evaluation, and refraction. Corneal topography, Orbscan II, and wavefront aberrometry were conducted. One eye was randomly assigned for aspheric treatment and applying eye tracking system. The other eye was treated without torsional eye tracking system. The outcome measures were uncorrected visual acuity (UCVA), best corrected visual acuity (BCVA), contrast sensitivity, corneal irregularity index in 3 mm and 5 mm optical zones in Orbscan II, and mean total HOAs at the 6-monthvisit. Fifty eyes of 25 patients were enrolled. Mean UCVA was improved significantly in both the study and control groups in the 6-month post-operative follow-up. There was no significant difference between the 2 groups in UCVA and BCVA (P = 0.185 and P = 0.176, respectively). Total HOAs increased in both groups after PRK. However, they were lower in eyes treated with the eye tracking system (P eye tracker system (Bausch and Lomb Advanced) results in a more regular anterior surface of cornea. Therefore, we recommend it for surface laser refractive surgery.

  12. Personal Access Satellite System (PASS) study. Fiscal year 1989 results

    Science.gov (United States)

    Sue, Miles K. (Editor)

    1990-01-01

    The Jet Propulsion Laboratory is exploring the potential and feasibility of a personal access satellite system (PASS) that will offer the user greater freedom and mobility than existing or currently planned communications systems. Studies performed in prior years resulted in a strawman design and the identification of technologies that are critical to the successful implementation of PASS. The study efforts in FY-89 were directed towards alternative design options with the objective of either improving the system performance or alleviating the constraints on the user terminal. The various design options and system issues studied this year and the results of the study are presented.

  13. Advanced Microelectronics Technologies for Future Small Satellite Systems

    Science.gov (United States)

    Alkalai, Leon

    1999-01-01

    Future small satellite systems for both Earth observation as well as deep-space exploration are greatly enabled by the technological advances in deep sub-micron microelectronics technologies. Whereas these technological advances are being fueled by the commercial (non-space) industries, more recently there has been an exciting new synergism evolving between the two otherwise disjointed markets. In other words, both the commercial and space industries are enabled by advances in low-power, highly integrated, miniaturized (low-volume), lightweight, and reliable real-time embedded systems. Recent announcements by commercial semiconductor manufacturers to introduce Silicon On Insulator (SOI) technology into their commercial product lines is driven by the need for high-performance low-power integrated devices. Moreover, SOI has been the technology of choice for many space semiconductor manufacturers where radiation requirements are critical. This technology has inherent radiation latch-up immunity built into the process, which makes it very attractive to space applications. In this paper, we describe the advanced microelectronics and avionics technologies under development by NASA's Deep Space Systems Technology Program (also known as X2000). These technologies are of significant benefit to both the commercial satellite as well as the deep-space and Earth orbiting science missions. Such a synergistic technology roadmap may truly enable quick turn-around, low-cost, and highly capable small satellite systems for both Earth observation as well as deep-space missions.

  14. Quick-Eye: Examination of Human Performance Characteristics Using Eye Tracking and Manual-Based Control Systems for Monitoring Multiple Displays

    Science.gov (United States)

    2013-03-01

    integration effort to combine eye - tracking technology into a multiple display information system, validation of the resulting system, and results of...studies conducted to determine the performance impact to response time, accuracy, and user workload by using eye - tracking input instead of manual controls to switch control among multiple displays.

  15. Satellite Power Systems (SPS) concept definition study. Volume 4: SPS point design definition

    Science.gov (United States)

    Hanley, G.

    1978-01-01

    The satellite power systems point design concept is described. The concept definition includes satellite, ground and space systems, and their relationships. Emphasis is placed on the definition of the GaAlAs photovoltaic satellite system. The major subsystems of the satellite system including power conversion, power distribution and control, microwave, attitude control and stationkeeping, thermal control, structures, and information management and control are discussed.

  16. Concept of an Effective Sentinel-1 Satellite SAR Interferometry System

    OpenAIRE

    2016-01-01

    This brief study introduces a partially working concept being developed at IT4Innovations supercomputer (HPC) facility. This concept consists of several modules that form a whole body of an efficient system for observation of terrain or objects displacements using satellite SAR interferometry (InSAR). A metadata database helps to locate data stored in various storages and to perform basic analyzes. A special database has been designed to describe Sentinel-1 data, on its burst level. Custom Se...

  17. System analysis for millimeter-wave communication satellites

    Science.gov (United States)

    Holland, L. D.; Hilsen, N. B.; Gallagher, J. J.; Stevens, G.

    1980-01-01

    Research and development needs for millimeter-wave space communication systems are presented. Assumed propagation fade statistics are investigated along with high data rate diversity link and storage. The development of reliable ferrite switches, and high performance receivers and transmitters is discussed, in addition to improved tolerance of dish and lens fabrication for the antennas. The typical cost for using a simplex voice channel via a high capacity 40/50 GHz satellite is presented.

  18. Management approach recommendations. Earth Observatory Satellite system definition study (EOS)

    Science.gov (United States)

    1974-01-01

    Management analyses and tradeoffs were performed to determine the most cost effective management approach for the Earth Observatory Satellite (EOS) Phase C/D. The basic objectives of the management approach are identified. Some of the subjects considered are as follows: (1) contract startup phase, (2) project management control system, (3) configuration management, (4) quality control and reliability engineering requirements, and (5) the parts procurement program.

  19. 77 FR 58579 - Certain Two-Way Global Satellite Communication Devices, System and Components Thereof...

    Science.gov (United States)

    2012-09-21

    ... COMMISSION Certain Two-Way Global Satellite Communication Devices, System and Components Thereof; Institution...-way global satellite communication devices, system and components thereof by reason of infringement of... after importation of certain two-way global satellite communication devices, system and components...

  20. 78 FR 31576 - Enforcement Proceeding; Certain Two-Way Global Satellite Communication Devices, System and...

    Science.gov (United States)

    2013-05-24

    ... Proceeding; Certain Two-Way Global Satellite Communication Devices, System and Components Thereof; Notice of... United States after importation of certain two-way global satellite communication devices, system and... States after importation any two-way global satellite communication devices, system, and components...

  1. A preliminary design for a satellite power system

    Science.gov (United States)

    Enriquez, Clara V.; Kokaly, Ray; Nandi, Saumya; Timmons, Mike; Garrard, Mark; Mercado, Rommel; Rogers, Brian; Ugaz, Victor

    1991-01-01

    Outlined here is a preliminary design for a Solar Power Satellite (SPS) system. The SPS will provide a clean, reliable source of energy for mass consumption. The system will use satellites in geostationary orbits around the Earth to capture the sun's energy. The intercepted sunlight will be converted to laser beam energy which can be transmitted to the Earth's surface. Ground systems on the Earth will convert the transmissions from space into electric power. The preliminary design for the SPS consists of one satellite in orbit around the Earth transmitting to one ground station. The SPs technology uses multi-layer solar cell technology arranged on a 20 sq km planar array to intercept sunlight and convert it to an electric voltage. Power conditioning devices then send the electricity to a laser, which transmits the power to the surface of the Earth. A ground station will convert the beam into electricity. Construction will take place in low Earth orbit and array sections, 20 in total, will be sailed on the solar wind out to the GEO location in 150 days. These individual transportation sections are referred to as solar sailing panels (SSAPs). The primary truss elements used to support the arrays are composed on composite tubular members in a pentahedral arrangement. Smart segments consisting of passive and active damping devices will increase the control of dynamic SPS modes.

  2. Present and Future Trends in Military Satellite Communication Systems

    Directory of Open Access Journals (Sweden)

    C.K. Chatterjee

    1993-01-01

    Full Text Available Recent years have seen a phenomenal growth in the field of satellite communications. Satcom systems offer many advantages for military applications which include wide area coverage, rapid deployment, flexible networking and long range service to moving platforms like ships, aircraft and vehicles. This paper gives an overview of the special features and future trends in military satcom systems. A brief account of various countermeasures against threats, use of EHF, spread-spectrum techniques and on board processing has also been given. Major technological advances are anticipated in near future to realise high capacity, secure and survivable satcom systems for Defence applications.

  3. Global navigation satellite systems, inertial navigation, and integration

    CERN Document Server

    Grewal, Mohinder S; Bartone, Chris G

    2013-01-01

    An updated guide to GNSS, and INS, and solutions to real-world GNSS/INS problems with Kalman filtering Written by recognized authorities in the field, this third edition of a landmark work provides engineers, computer scientists, and others with a working familiarity of the theory and contemporary applications of Global Navigation Satellite Systems (GNSS), Inertial Navigational Systems, and Kalman filters. Throughout, the focus is on solving real-world problems, with an emphasis on the effective use of state-of-the-art integration techniques for those systems, especially the application of Kal

  4. Satellite Constellation Design with Adaptively Continuous Ant System Algorithm

    Institute of Scientific and Technical Information of China (English)

    He Quan; Han Chao

    2007-01-01

    The ant system algorithm (ASA) has proved to be a novel meta-heuristic algorithm to solve many multivariable problems. In this paper, the earth coverage of satellite constellation is analyzed and a (n + 1)-fold coverage rate is put forward to evaluate the coverage performance of a satellite constellation. An optimization model of constellation parameters is established on the basis of the coverage performance. As a newly developed method, ASA can be applied to optimize the constellation parameters. In order to improve the ASA,a rule for adaptive number of ants is proposed, by which the search range is obviously enlarged and the convergence speed increased.Simulation results have shown that the ASA is more quick and efficient than other methods.

  5. Real Time Fire Reconnaissance Satellite Monitoring System Failure Model

    Science.gov (United States)

    Nino Prieto, Omar Ariosto; Colmenares Guillen, Luis Enrique

    2013-09-01

    In this paper the Real Time Fire Reconnaissance Satellite Monitoring System is presented. This architecture is a legacy of the Detection System for Real-Time Physical Variables which is undergoing a patent process in Mexico. The methodologies for this design are the Structured Analysis for Real Time (SA- RT) [8], and the software is carried out by LACATRE (Langage d'aide à la Conception d'Application multitâche Temps Réel) [9,10] Real Time formal language. The system failures model is analyzed and the proposal is based on the formal language for the design of critical systems and Risk Assessment; AltaRica. This formal architecture uses satellites as input sensors and it was adapted from the original model which is a design pattern for physical variation detection in Real Time. The original design, whose task is to monitor events such as natural disasters and health related applications, or actual sickness monitoring and prevention, as the Real Time Diabetes Monitoring System, among others. Some related work has been presented on the Mexican Space Agency (AEM) Creation and Consultation Forums (2010-2011), and throughout the International Mexican Aerospace Science and Technology Society (SOMECYTA) international congress held in San Luis Potosí, México (2012). This Architecture will allow a Real Time Fire Satellite Monitoring, which will reduce the damage and danger caused by fires which consumes the forests and tropical forests of Mexico. This new proposal, permits having a new system that impacts on disaster prevention, by combining national and international technologies and cooperation for the benefit of humankind.

  6. Planning for a data base system to support satellite conceptual design

    Science.gov (United States)

    Claydon, C. R.

    1976-01-01

    The conceptual design of an automated satellite design data base system is presented. The satellite catalog in the system includes data for all earth orbital satellites funded to the hardware stage for launch between 1970 and 1980, and provides a concise compilation of satellite capabilities and design parameters. The cost of satellite subsystems and components will be added to the base. Data elements are listed and discussed. Sensor and science and applications opportunities catalogs will be included in the data system. Capabilities of the BASIS storage, retrieval, and analysis system are used in the system design.

  7. Assessment of a satellite power system and six alternative technologies

    Energy Technology Data Exchange (ETDEWEB)

    Wolsko, T.; Whitfield, R.; Samsa, M.; Habegger, L.S.; Levine, E.; Tanzman, E.

    1981-04-01

    The satellite power system is assessed in comparison to six alternative technologies. The alternatives are: central-station terrestrial photovoltaic systems, conventional coal-fired power plants, coal-gasification/combined-cycle power plants, light water reactor power plants, liquid-metal fast-breeder reactors, and fusion. The comparison is made regarding issues of cost and performance, health and safety, environmental effects, resources, socio-economic factors, and insitutional issues. The criteria for selecting the issues and the alternative technologies are given, and the methodology of the comparison is discussed. Brief descriptions of each of the technologies considered are included. (LEW)

  8. 47 CFR 25.159 - Limits on pending applications and unbuilt satellite systems.

    Science.gov (United States)

    2010-10-01

    ... satellite systems. 25.159 Section 25.159 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) COMMON CARRIER SERVICES SATELLITE COMMUNICATIONS Applications and Licenses Processing of Applications § 25.159 Limits on pending applications and unbuilt satellite systems. (a) Applicants with a total...

  9. Modular High-Energy Systems for Solar Power Satellites

    Science.gov (United States)

    Howell, Joe T.; Carrington, Connie K.; Marzwell, Neville I.; Mankins, John C.

    2006-01-01

    Modular High-Energy Systems are Stepping Stones to provide capabilities for energy-rich infrastructure located in space to support a variety of exploration scenarios as well as provide a supplemental source of energy during peak demands to ground grid systems. Abundant renewable energy at lunar or other locations could support propellant production and storage in refueling scenarios that enable affordable exploration. Renewable energy platforms in geosynchronous Earth orbits can collect and transmit power to satellites, or to Earth-surface locations. Energy-rich space technologies also enable the use of electric-powered propulsion systems that could efficiently deliver cargo and exploration facilities to remote locations. A first step to an energy-rich space infrastructure is a 100-kWe class solar-powered platform in Earth orbit. The platform would utilize advanced technologies in solar power collection and generation, power management and distribution, thermal management, electric propulsion, wireless avionics, autonomous in space rendezvous and docking, servicing, and robotic assembly. It would also provide an energy-rich free-flying platform to demonstrate in space a portfolio of technology flight experiments. This paper summary a preliminary design concept for a 100-kWe solar-powered satellite system to demonstrate in-flight a variety of advanced technologies, each as a separate payload. These technologies include, but are not limited to state-of-the-art solar concentrators, highly efficient multi-junction solar cells, integrated thermal management on the arrays, and innovative deployable structure design and packaging to enable the 100-kW satellite feasible to launch on one existing launch vehicle. Higher voltage arrays and power distribution systems (PDS) reduce or eliminate the need for massive power converters, and could enable direct-drive of high-voltage solar electric thrusters.

  10. Guidance, Navigation, and Control System for Maneuverable Pico-Satellites Project

    Data.gov (United States)

    National Aeronautics and Space Administration — A compact, low-power GN&C system is essential to the success of pico-satellite Automated Rendezvous and Docking (AR&D). Austin Satellite Design (ASD)...

  11. Preface: BeiDou Navigation Satellite System (BDS)/GNSS+: Recent progress and new applications

    Science.gov (United States)

    Jin, Shuanggen

    2017-02-01

    Nowadays, the new China's BeiDou Navigation Satellite System (BDS) has been developed well. At the end of 2016, over 23 BDS satellites were launched, including five geostationary Earth orbit (GEO) satellites, five inclined geosynchronous orbit (IGSO) satellites and nine medium Earth orbit (MEO) satellites. The current BDS service covers China and most Asia-Pacific regions with accuracy of better than 10 m in positioning, 0.2 m/s in velocity and 50 ns in timing. The BDS with global coverage will be completely established by 2020 with five GEO satellites and 30 MEO satellites. The main function of BDS is the positioning, navigation and timing (PNT) as well as short message communications. Together with the United States' GPS, Russia's GLONASS and the European Union's Galileo system as well as other regional augmentation systems, more new applications of multi-Global Navigation Satellite Systems (GNSS) will be exploited and realized in the next decades.

  12. Guidance, Navigation, and Control System for Maneuverable Pico-Satellites Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Pico-satellites are an emerging new class of spacecraft. Maneuverable pico-satellites require active guidance, navigation, and control (GN&C) systems to perform...

  13. Radiometric Cross-Calibration of the Chilean Satellite FASat-C Using RapidEye and EO-1 Hyperion Data and a Simultaneous Nadir Overpass Approach

    Directory of Open Access Journals (Sweden)

    Carolina Barrientos

    2016-07-01

    Full Text Available The absolute radiometric calibration of a satellite sensor is the critical factor that ensures the usefulness of the acquired data for quantitative applications on remote sensing. This work presents the results of the first cross-calibration of the sensor on board the Sistema Satelital de Observación de la Tierra (SSOT Chilean satellite or Air Force Satellite FASat-C. RapidEye-MSI was chosen as the reference sensor, and a simultaneous Nadir Overpass Approach (SNO was applied. The biases caused by differences in the spectral responses of both instruments were compensated through an adjustment factor derived from EO-1 Hyperion data. Through this method, the variations affecting the radiometric response of New AstroSat Optical Modular Instrument (NAOMI-1, have been corrected based on collections over the Frenchman Flat calibration site. The results of a preliminary evaluation of the pre-flight and updated coefficients have shown a significant improvement in the accuracy of at-sensor radiances and TOA reflectances: an average agreement of 2.63% (RMSE was achieved for the multispectral bands of both instruments. This research will provide a basis for the continuity of calibration and validation tasks of future Chilean space missions.

  14. Designing nonuniform satellite systems for continuous global coverage using equatorial and polar circular orbits

    Science.gov (United States)

    Ulybyshev, S. Yu.

    2016-07-01

    We present a method for designing nonuniform satellite systems for continuous global coverage using a combination of equatorial and near-polar satellite segments in circular orbits. Equations are derived to determine the basic design parameters of the satellite system itself and the conditions of its closure at the joint of near-polar and equatorial segments. We analyze specific features of near-polar and equatorial satellite systems and their advantages and disadvantages compared with existing classes of near-polar phased and kinematically correct satellite systems. We estimate the minimum required number of spacecrafts in satellite systems for a given fold of coverage and present calculated dependences for classes of near-polar phased and equatorial satellite systems with different types of closure. For the class of kinematically correct satellite systems, we analyze the characteristics of systems with a minimum spacecraft flight height and reveal that the number of satellites in the orbital plane depends on the flight height for different folds of coverage. We bring examples of the best near-polar equatorial satellite systems of global coverage for different folds and a class of satellite systems with a fixed number of spacecrafts and orbital planes in them.

  15. Monitoring of the Spatial Distribution and Temporal Dynamics of the Green Vegetation Fraction of Croplands in Southwest Germany Using High-Resolution RapidEye Satellite Images

    Science.gov (United States)

    Imukova, Kristina; Ingwersen, Joachim; Streck, Thilo

    2014-05-01

    The green vegetation fraction (GVF) is a key input variable to the evapotranspiration scheme applied in the widely used NOAH land surface model (LSM). In standard applications of the NOAH LSM, the GVF is taken from a global map with a 15 km×15 km resolution. The central objective of the present study was (a) to derive gridded GVF data in a high spatial and temporal resolution from RapidEye images for a region in Southwest Germany, and (b) to improve the representation of the GVF dynamics of croplands in the NOAH LSM for a better simulation of water and energy exchange between land surface and atmosphere. For the region under study we obtained monthly RapidEye satellite images with a resolution 5 m×5 m by the German Aerospace Center (DLR). The images hold five spectral bands: blue, green, red, red-edge and near infrared (NIR). The GVF dynamics were determined based on the Normalized Difference Vegetation Index (NDVI) calculated from the red and near-infrared bands of the satellite images. The satellite GVF data were calibrated and validated against ground truth measurements. Digital colour photographs above the canopy were taken with a boom-mounted digital camera at fifteen permanently marked plots (1 m×1 m). Crops under study were winter wheat, winter rape and silage maize. The GVF was computed based on the red and the green band of the photographs according to Rundquist's method (2002). Based on the obtained calibration scheme GVF maps were derived in a monthly resolution for the region. Our results confirm a linear relationship between GVF and NDVI and demonstrate that it is possible to determine the GVF of croplands from RapidEye images based on a simple two end-member mixing model. Our data highlight the high variability of the GVF in time and space. At the field scale, the GVF was normally distributed with a coefficient of variation of about 32%. Variability was mainly caused by soil heterogeneities and management differences. At the regional scale the GVF

  16. Spatial heterogeneity in mangroves assessed by GeoEye-1 satellite data: a case-study in Zhanjiang Mangrove National Nature Reserve (ZMNNR, China

    Directory of Open Access Journals (Sweden)

    K. Leempoel

    2013-02-01

    Full Text Available Mangrove forests, which are declining across the globe mainly because of human intervention, require an evaluation of their past and present status (e.g. areal extent, species-level distribution, etc. to better implement conservation and management strategies. In this paper, mangrove cover dynamics at Gaoqiao (under the jurisdiction of Zhanjiang Mangrove National Nature Reserve – ZMNNR, P. R. China were assessed through time using 1967 (Corona KH-4B, 2000 (Landsat ETM+, and 2009 (GeoEye-1 satellite imagery. An important decline in mangrove cover (−36% was observed between 1967 and 2009 due to dike construction for agriculture (paddy and aquaculture practices. Moreover, dike construction prevented mangroves from expanding landward. Although a small increase of mangrove area was observed between 2000 and 2009 (+24%, the ratio mangrove/aquaculture kept decreasing due to increased aquaculture at the expense of rice culture. In the land-use/cover map based on ground-truth data (5 m × 5 m plot-based tree measurements (August–September, 2009 and spectral reflectance values (obtained from pansharpened GeoEye-1, both Bruguiera gymnorrhiza and small Aegiceras corniculatum are distinguishable at 73–100% accuracy, whereas tall A. corniculatum is identifiable at only 53% due to its mixed vegetation stands close to B. gymnorrhiza (classification accuracy: 85%. Sand proportion in the sediment showed significant differences (Kruskal-Wallis/ANOVA, P < 0.05 between the three mangrove classes (B. gymnorrhiza and small and tall A. corniculatum. Distribution of tall A. corniculatum on the convex side of creeks and small A.corniculatum on the concave side (with sand show intriguing patterns of watercourse changes. Overall, the advantage of very high resolution satellite images like GeoEye-1 for mangrove spatial heterogeneity assessment and/or species-level discrimination is well demonstrated

  17. Joint Polar Satellite System (JPSS) Common Ground System (CGS) Block 3.0 Communications Strategies

    Science.gov (United States)

    Miller, S. W.; Grant, K. D.; Ottinger, K.

    2015-12-01

    The National Oceanic and Atmospheric Administration (NOAA) and National Aeronautics and Space Administration (NASA) are jointly acquiring the next-generation civilian weather and environmental satellite system: the Joint Polar Satellite System (JPSS). The JPSS program is the follow-on for both space and ground systems to the Polar-orbiting Operational Environmental Satellites (POES) managed by NOAA. The JPSS satellites will carry a suite of sensors designed to collect meteorological, oceanographic, climatological and geophysical observations of the Earth. The ground processing system for JPSS is known as the JPSS Common Ground System (JPSS CGS). Developed and maintained by Raytheon Intelligence, Information and Services (IIS), the CGS is a globally distributed, multi-mission system serving NOAA, NASA and their national and international partners. The CGS has demonstrated its scalability and flexibility to incorporate multiple missions efficiently and with minimal cost, schedule and risk, while strengthening global partnerships in weather and environmental monitoring. In a highly successful international partnership between NOAA and the European Organisation for the Exploitation of Meteorological Satellites (EUMETSAT), the CGS currently provides data routing from McMurdo Station in Antarctica to the EUMETSAT processing center in Darmstadt, Germany. Continuing and building upon that partnership, NOAA and EUMETSAT are collaborating on the development of a new path forward for the 2020's. One approach being explored is a concept of operations where each organization shares satellite downlink resources with the other. This paper will describe that approach, as well as modeling results that demonstrate its feasibility and expected performance.

  18. Diagnosis of Autism Using an Eye Tracking System

    OpenAIRE

    2016-01-01

    International audience; Autism Spectrum Disorders(ASD) are characterized by a deficitin social integration, anguage development, and restricted interests. ASD is defined as a prevalence development life disability. However, children who are early diagnosed and intervention improve long-term prognosis.This project proposes to detect autism in children at a first level (preclinical stage) using a tool "eye tracking" highly cost-effective and mbedded in a tablet. The results obtained with thissy...

  19. Production process for advanced space satellite system cables/interconnects.

    Energy Technology Data Exchange (ETDEWEB)

    Mendoza, Luis A.

    2007-12-01

    This production process was generated for the satellite system program cables/interconnects group, which in essences had no well defined production process. The driver for the development of a formalized process was based on the set backs, problem areas, challenges, and need improvements faced from within the program at Sandia National Laboratories. In addition, the formal production process was developed from the Master's program of Engineering Management for New Mexico Institute of Mining and Technology in Socorro New Mexico and submitted as a thesis to meet the institute's graduating requirements.

  20. Satellite Power System (SPS) financial/management scenarios

    Science.gov (United States)

    Vajk, J. P.

    1978-01-01

    The possible benefits of a Satellite Power System (SPS) program, both domestically and internationally, justify detailed and imaginative investigation of the issues involved in financing and managing such a large-scale program. In this study, ten possible methods of financing a SPS program are identified ranging from pure government agency to private corporations. The following were analyzed and evaluated: (1) capital requirements for SPS; (2) ownership and control; (3) management principles; (4) organizational forms for SPS; (5) criteria for evaluation; (6) detailed description and preliminary evaluation of alternatives; (7) phased approaches; and (8) comparative evaluation. Key issues and observations and recommendations for further study are also presented.

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

    KAUST Repository

    Sadek, Mirette

    2012-06-01

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

  2. Efficient medium access control protocol for geostationary satellite systems

    Institute of Scientific and Technical Information of China (English)

    王丽娜; 顾学迈

    2004-01-01

    This paper proposes an efficient medium access control (MAC) protocol based on multifrequency-time division multiple access (MF-TDMA) for geostationary satellite systems deploying multiple spot-beams and onboard processing,which uses a method of random reservation access with movable boundaries to dynamically request the transmission slots and can transmit different types of traffic. The simulation results have shown that our designed MAC protocol can achieve a high bandwidth utilization, while providing the required quality of service (QoS) for each class of service.

  3. Optical eye tracking system for real-time noninvasive tumor localization in external beam radiotherapy.

    Science.gov (United States)

    Via, Riccardo; Fassi, Aurora; Fattori, Giovanni; Fontana, Giulia; Pella, Andrea; Tagaste, Barbara; Riboldi, Marco; Ciocca, Mario; Orecchia, Roberto; Baroni, Guido

    2015-05-01

    External beam radiotherapy currently represents an important therapeutic strategy for the treatment of intraocular tumors. Accurate target localization and efficient compensation of involuntary eye movements are crucial to avoid deviations in dose distribution with respect to the treatment plan. This paper describes an eye tracking system (ETS) based on noninvasive infrared video imaging. The system was designed for capturing the tridimensional (3D) ocular motion and provides an on-line estimation of intraocular lesions position based on a priori knowledge coming from volumetric imaging. Eye tracking is performed by localizing cornea and pupil centers on stereo images captured by two calibrated video cameras, exploiting eye reflections produced by infrared illumination. Additionally, torsional eye movements are detected by template matching in the iris region of eye images. This information allows estimating the 3D position and orientation of the eye by means of an eye local reference system. By combining ETS measurements with volumetric imaging for treatment planning [computed tomography (CT) and magnetic resonance (MR)], one is able to map the position of the lesion to be treated in local eye coordinates, thus enabling real-time tumor referencing during treatment setup and irradiation. Experimental tests on an eye phantom and seven healthy subjects were performed to assess ETS tracking accuracy. Measurements on phantom showed an overall median accuracy within 0.16 mm and 0.40° for translations and rotations, respectively. Torsional movements were affected by 0.28° median uncertainty. On healthy subjects, the gaze direction error ranged between 0.19° and 0.82° at a median working distance of 29 cm. The median processing time of the eye tracking algorithm was 18.60 ms, thus allowing eye monitoring up to 50 Hz. A noninvasive ETS prototype was designed to perform real-time target localization and eye movement monitoring during ocular radiotherapy treatments. The

  4. Optical eye tracking system for real-time noninvasive tumor localization in external beam radiotherapy

    Energy Technology Data Exchange (ETDEWEB)

    Via, Riccardo, E-mail: riccardo.via@polimi.it; Fassi, Aurora; Fattori, Giovanni [Dipartimento di Elettronica, Informazione e Bioingegneria, Politecnico di Milano, Milano 20133 (Italy); Fontana, Giulia; Pella, Andrea; Tagaste, Barbara; Ciocca, Mario [CNAO Centro Nazionale di Adroterapia Oncologica, Pavia 27100 (Italy); Riboldi, Marco; Baroni, Guido [Dipartimento di Elettronica, Informazione e Bioingegneria, Politecnico di Milano, Milano 20133, Italy and CNAO Centro Nazionale di Adroterapia Oncologica, Pavia 27100 (Italy); Orecchia, Roberto [CNAO Centro Nazionale di Adroterapia Oncologica, Pavia 27100, Italy and European Institute of Oncology, Milano 20141 (Italy)

    2015-05-15

    Purpose: External beam radiotherapy currently represents an important therapeutic strategy for the treatment of intraocular tumors. Accurate target localization and efficient compensation of involuntary eye movements are crucial to avoid deviations in dose distribution with respect to the treatment plan. This paper describes an eye tracking system (ETS) based on noninvasive infrared video imaging. The system was designed for capturing the tridimensional (3D) ocular motion and provides an on-line estimation of intraocular lesions position based on a priori knowledge coming from volumetric imaging. Methods: Eye tracking is performed by localizing cornea and pupil centers on stereo images captured by two calibrated video cameras, exploiting eye reflections produced by infrared illumination. Additionally, torsional eye movements are detected by template matching in the iris region of eye images. This information allows estimating the 3D position and orientation of the eye by means of an eye local reference system. By combining ETS measurements with volumetric imaging for treatment planning [computed tomography (CT) and magnetic resonance (MR)], one is able to map the position of the lesion to be treated in local eye coordinates, thus enabling real-time tumor referencing during treatment setup and irradiation. Experimental tests on an eye phantom and seven healthy subjects were performed to assess ETS tracking accuracy. Results: Measurements on phantom showed an overall median accuracy within 0.16 mm and 0.40° for translations and rotations, respectively. Torsional movements were affected by 0.28° median uncertainty. On healthy subjects, the gaze direction error ranged between 0.19° and 0.82° at a median working distance of 29 cm. The median processing time of the eye tracking algorithm was 18.60 ms, thus allowing eye monitoring up to 50 Hz. Conclusions: A noninvasive ETS prototype was designed to perform real-time target localization and eye movement monitoring

  5. The Federated Satellite Systems paradigm: Concept and business case evaluation

    Science.gov (United States)

    Golkar, Alessandro; Lluch i Cruz, Ignasi

    2015-06-01

    This paper defines the paradigm of Federated Satellite Systems (FSS) as a novel distributed space systems architecture. FSS are networks of spacecraft trading previously inefficiently allocated and unused resources such as downlink bandwidth, storage, processing power, and instrument time. FSS holds the promise to enhance cost-effectiveness, performance and reliability of existing and future space missions, by networking different missions and effectively creating a pool of resources to exchange between participants in the federation. This paper introduces and describes the FSS paradigm, and develops an approach integrating mission analysis and economic assessments to evaluate the feasibility of the business case of FSS. The approach is demonstrated on a case study on opportunities enabled by FSS to enhance space exploration programs, with particular reference to the International Space Station. The application of the proposed methodology shows that the FSS concept is potentially able to create large commercial markets of in-space resources, by providing the technical platform to offer the opportunity for spacecraft to share or make use of unused resources within their orbital neighborhood. It is shown how the concept is beneficial to satellite operators, space agencies, and other stakeholders of the space industry to more flexibly interoperate space systems as a portfolio of assets, allowing unprecedented collaboration among heterogeneous types of missions.

  6. Basic performance of BeiDou-2 navigation satellite system used in LEO satellites precise orbit determination

    Directory of Open Access Journals (Sweden)

    Liu Junhong

    2014-10-01

    Full Text Available The visibility for low earth orbit (LEO satellites provided by the BeiDou-2 system is analyzed and compared with the global positioning system (GPS. In addition, the spaceborne receivers’ observations are simulated by the BeiDou satellites broadcast ephemeris and LEO satellites orbits. The precise orbit determination (POD results show that the along-track component accuracy is much better over the service area than the non-service area, while the accuracy of the other two directions keeps at the same level over different areas. However, the 3-dimensional (3D accuracy over the two areas shows almost no difference. Only taking into consideration the observation noise and navigation satellite ephemeris errors, the 3D accuracy of the POD is about 30 cm. As for the precise relative orbit determination (PROD, the 3D accuracy is much better over the eastern hemisphere than that of the western hemisphere. The baseline length accuracy is 3.4 mm over the service area, and it is still better than 1 cm over the non-service area. This paper demonstrates that the BeiDou regional constellation could provide global service to LEO satellites for the POD and the PROD. Finally, the benefit of geostationary earth orbit (GEO satellites is illustrated for POD.

  7. Basic performance of BeiDou-2 navigation satellite system used in LEO satellites precise orbit determination

    Institute of Scientific and Technical Information of China (English)

    Liu Junhong; Gu Defeng; Ju Bing; Yao Jing; Duan Xiaojun; Yi Dongyun

    2014-01-01

    The visibility for low earth orbit (LEO) satellites provided by the BeiDou-2 system is analyzed and compared with the global positioning system (GPS). In addition, the spaceborne receivers’ observations are simulated by the BeiDou satellites broadcast ephemeris and LEO satel-lites orbits. The precise orbit determination (POD) results show that the along-track component accuracy is much better over the service area than the non-service area, while the accuracy of the other two directions keeps at the same level over different areas. However, the 3-dimensional (3D) accuracy over the two areas shows almost no difference. Only taking into consideration the observation noise and navigation satellite ephemeris errors, the 3D accuracy of the POD is about 30 cm. As for the precise relative orbit determination (PROD), the 3D accuracy is much better over the eastern hemisphere than that of the western hemisphere. The baseline length accuracy is 3.4 mm over the service area, and it is still better than 1 cm over the non-service area. This paper demon-strates that the BeiDou regional constellation could provide global service to LEO satellites for the POD and the PROD. Finally, the benefit of geostationary earth orbit (GEO) satellites is illustrated for POD.

  8. Secondary reconstruction of severe contracted eye socket using modified ocular conformer-drainage tube system.

    Science.gov (United States)

    Li, Jin; Lin, Ming; Ge, Shengfang; Fan, Xianqun

    2012-07-01

    Eye socket reconstruction has been previously reported; however, few reports address reconstruction in cases of socket contracture after graft failure. This is a retrospective observational case study of 42 patients who had previously undergone eye socket reconstruction after posttraumatic enucleation owing to severe thermal or chemical injury, and each of whom presented with a severe contracted eye socket. Patients underwent free skin grafts and the placement of a modified ocular conformer-drainage tube system. Eye sockets of adequate size were created in the 42 patients. Three patients presented with gradual extrusion of the eye prosthesis due to recurrent contraction of the inferior fornix after treatment. These patients agreed to further operative procedures 6 months after secondary reconstruction surgery, which resulted in mild upward tilting of the eye prosthesis without extrusion. The prosthetic eyes fit well in all of the secondary reconstructed sockets using this technique. Our studies suggest that the modified ocular conformer-drainage tube system can efficiently control infection after secondary reconstruction of the posttraumatic contracted socket and may result in less shrinkage of skin grafts.

  9. The µ-opioid system promotes visual attention to faces and eyes.

    Science.gov (United States)

    Chelnokova, Olga; Laeng, Bruno; Løseth, Guro; Eikemo, Marie; Willoch, Frode; Leknes, Siri

    2016-12-01

    Paying attention to others' faces and eyes is a cornerstone of human social behavior. The µ-opioid receptor (MOR) system, central to social reward-processing in rodents and primates, has been proposed to mediate the capacity for affiliative reward in humans. We assessed the role of the human MOR system in visual exploration of faces and eyes of conspecifics. Thirty healthy males received a novel, bidirectional battery of psychopharmacological treatment (an MOR agonist, a non-selective opioid antagonist, or placebo, on three separate days). Eye-movements were recorded while participants viewed facial photographs. We predicted that the MOR system would promote visual exploration of faces, and hypothesized that MOR agonism would increase, whereas antagonism decrease overt attention to the information-rich eye region. The expected linear effect of MOR manipulation on visual attention to the stimuli was observed, such that MOR agonism increased while antagonism decreased visual exploration of faces and overt attention to the eyes. The observed effects suggest that the human MOR system promotes overt visual attention to socially significant cues, in line with theories linking reward value to gaze control and target selection. Enhanced attention to others' faces and eyes represents a putative behavioral mechanism through which the human MOR system promotes social interest.

  10. Performance Evaluation of Data Compression Systems Applied to Satellite Imagery

    Directory of Open Access Journals (Sweden)

    Lilian N. Faria

    2012-01-01

    Full Text Available Onboard image compression systems reduce the data storage and downlink bandwidth requirements in space missions. This paper presents an overview and evaluation of some compression algorithms suitable for remote sensing applications. Prediction-based compression systems, such as DPCM and JPEG-LS, and transform-based compression systems, such as CCSDS-IDC and JPEG-XR, were tested over twenty multispectral (5-band images from CCD optical sensor of the CBERS-2B satellite. Performance evaluation of these algorithms was conducted using both quantitative rate-distortion measurements and subjective image quality analysis. The PSNR, MSSIM, and compression ratio results plotted in charts and the SSIM maps are used for comparison of quantitative performance. Broadly speaking, the lossless JPEG-LS outperforms other lossless compression schemes, and, for lossy compression, JPEG-XR can provide lower bit rate and better tradeoff between compression ratio and image quality.

  11. A 2D eye gaze estimation system with low-resolution webcam images

    Directory of Open Access Journals (Sweden)

    Kim Jin

    2011-01-01

    Full Text Available Abstract In this article, a low-cost system for 2D eye gaze estimation with low-resolution webcam images is presented. Two algorithms are proposed for this purpose, one for the eye-ball detection with stable approximate pupil-center and the other one for the eye movements' direction detection. Eyeball is detected using deformable angular integral search by minimum intensity (DAISMI algorithm. Deformable template-based 2D gaze estimation (DTBGE algorithm is employed as a noise filter for deciding the stable movement decisions. While DTBGE employs binary images, DAISMI employs gray-scale images. Right and left eye estimates are evaluated separately. DAISMI finds the stable approximate pupil-center location by calculating the mass-center of eyeball border vertices to be employed for initial deformable template alignment. DTBGE starts running with initial alignment and updates the template alignment with resulting eye movements and eyeball size frame by frame. The horizontal and vertical deviation of eye movements through eyeball size is considered as if it is directly proportional with the deviation of cursor movements in a certain screen size and resolution. The core advantage of the system is that it does not employ the real pupil-center as a reference point for gaze estimation which is more reliable against corneal reflection. Visual angle accuracy is used for the evaluation and benchmarking of the system. Effectiveness of the proposed system is presented and experimental results are shown.

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

    Science.gov (United States)

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

    1983-01-01

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

  13. The eye of Drosophila as a model system for studying intracellular signaling in ontogenesis and pathogenesis.

    Science.gov (United States)

    Katanaev, V L; Kryuchkov, M V

    2011-12-01

    Many human diseases are caused by malfunction of basic types of cellular activity such as proliferation, differentiation, apoptosis, cell polarization, and migration. In turn, these processes are associated with different routes of intracellular signal transduction. A number of model systems have been designed to study normal and abnormal cellular and molecular processes associated with pathogenesis. The developing eye of the fruit fly Drosophila melanogaster is one of these systems. The sequential development of compound eyes of this insect makes it possible to model human neurodegenerative diseases and mechanisms of carcinogenesis. In this paper we overview the program of the eye development in Drosophila, with emphasis on intracellular signaling pathways that regulate this complex process. We discuss in detail the roles of the Notch, Hedgehog, TGFβ, Wnt, and receptor tyrosine kinase signaling pathways in Drosophila eye development and human pathology. We also briefly describe the modern methods of experimentation with this model organism to analyze the function of human pathogenic proteins.

  14. Robot Arm Control and Having Meal Aid System with Eye Based Human-Computer Interaction (HCI)

    Science.gov (United States)

    Arai, Kohei; Mardiyanto, Ronny

    Robot arm control and having meal aid system with eye based HCI is proposed. The proposed system allows disabled person to select desirable food from the meal tray by their eyes only. Robot arm which is used for retrieving the desirable food is controlled by human eye. At the tip of the robot arm, tiny camera is equipped. Disabled person wear a glass of which a single Head Mount Display: HMD and tiny camera is mounted so that disabled person can take a look at the desired food and retrieve it by looking at the food displayed onto HMD. Experimental results show that disabled person can retrieve the desired food successfully. It also is confirmed that robot arm control by eye based HCI is much faster than that by hands.

  15. A low cost data logging system with satellite transmission capabilities

    Digital Repository Service at National Institute of Oceanography (India)

    Desa, E.S.; DeSa, E.J.; Desai, R.G.P.

    satellite navigator, deep sea echosounder, and a magnetometer on board a chartered research vessel. A novel data logger design was implemented with the extra option of transmitting logged data through the ships INMARSAT approved satellite terminal...

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

    Science.gov (United States)

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

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

  17. The changing world of global navigation satellite systems

    Science.gov (United States)

    Dow, John M.; Neilan, Ruth E.; Higgins, Matt; Arias, Felicitas

    The world of global navigation satellite systems (GNSS) has been changing very rapidly during the last years. New constellations are being developed in Europe (Galileo), India (IRNSS), Japan (QZNSS) and China (Compass), while both the US GPS and the Russian GLONASS programmes are engaged in very significant mediumto long-term improvements, which will make them even more valuable in the coming years to an ever wider range of civilian users. In addition, powerful regional augmentation systems are becoming (or have already become) operational, providing users with important real time information concerning the integrity of the signals being broadcast by those two systems: these include the US WAAS, the European EGNOS, the Japanese MSAS, the Indian GAGAN and others. Following a number of United Nations sponsored regional workshops, a report by an ad hoc UN "GNSS Action Team" and several preparatory meetings, the International Committee on GNSS (ICG) was established in December 2005 in Vienna, Austria. The ICG is an informal body with the main objective of promoting cooperation on matters of mutual interest related to civil satellite-based positioning, navigation, timing, and value-added services, as well as compatibility and interoperability among the GNSS systems. A further important objective is to encourage the use of GNSS to support sustainable development, particularly in the developing countries. The United Nations Office for Outer Space Affairs (UNOOSA) plays a key role in facilitating the work of the ICG. The members of the Committee are GNSS system providers, while international organisations representing users of GNSS can qualify for participation in the work of the Committee as associate members or observers. The interests of the space geodetic, mapping and timing communities are represented in particular through ICG associate membership of the IGS, IAG, FIG, IERS, while BIPM is an ICG observer. This paper will highlight the background of these developments

  18. System Design and Key Technologies of the GF-3 Satellite

    Directory of Open Access Journals (Sweden)

    ZHANG Qingjun

    2017-03-01

    Full Text Available GF-3 satellite, the first C band and multi-polarization SAR satellite in China, achieves breakthroughs in a number of core and key technologies. The satellite technology abides by the principle of “Demand Pulls, Technology Pushes”, forming a series of innovation point, and reaching or surpassing international level in main technical specification.

  19. Preliminary environmental assessment for the satellite power system (SPS)

    Energy Technology Data Exchange (ETDEWEB)

    1978-10-01

    A preliminary assessment of the impact of the Satellite Power System (SPS) on the environment is presented. Information that has appeared in documents referenced herein is integrated and assimilated. The state-of-knowledge as perceived from recently completed DOE-sponsored studies is disclosed, and prospective research and study programs that can advance the state-of-knowledge and provide an expanded data base for use in an assessment planned for 1980 are defined. Alternatives for research that may be implemented in order to achieve this advancement are also discussed in order that a plan can be selected which will be consistent with the fiscal and time constraints on the SPS Environmental Assessment Program. Health and ecological effects of microwave radiation, nonmicrowave effects on health and the environment (terrestrial operations and space operations), effects on the atmosphere, and effects on communications systems are examined in detail. (WHK)

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

    Science.gov (United States)

    Vernucci, A.; Craig, A. D.

    1993-01-01

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

  1. The silicon solar satellite power system - A net energy analysis

    Science.gov (United States)

    Hannon, B.; Naughton, J. P.

    The physical aspects and net energy balance of a Satellite Solar Power System (SSPS) are examined. The feasibility of operating with or without laser annealing for the cells, possible variations in the total system costs, the projected worth of the energy, and the R&D costs are explored. The energy needed to mine, refine, fabricate, manufacture, launch, and maintain the SSPS materials and structures are included in the energy analysis, and cost-to-energy ratio of energy used to energy produced graphs are provided for the cases of the use or non-use of laser annealing for radiation protection for the solar cells. The resulting energy ratios indicate that the reference SSPS compares unfavorably with coal or nuclear earth-based plants, although further research is necessary to determine what level of technology is actually required for construction of the SSPS.

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

    Science.gov (United States)

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

    1986-01-01

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

  3. Satellite-instrument system engineering best practices and lessons

    Science.gov (United States)

    Schueler, Carl F.

    2009-08-01

    This paper focuses on system engineering development issues driving satellite remote sensing instrumentation cost and schedule. A key best practice is early assessment of mission and instrumentation requirements priorities driving performance trades among major instrumentation measurements: Radiometry, spatial field of view and image quality, and spectral performance. Key lessons include attention to technology availability and applicability to prioritized requirements, care in applying heritage, approaching fixed-price and cost-plus contracts with appropriate attention to risk, and assessing design options with attention to customer preference as well as design performance, and development cost and schedule. A key element of success either in contract competition or execution is team experience. Perhaps the most crucial aspect of success, however, is thorough requirements analysis and flowdown to specifications driving design performance with sufficient parameter margin to allow for mistakes or oversights - the province of system engineering from design inception to development, test and delivery.

  4. Onboard Supervisor for the Ørsted Satellite Attitude Control System

    DEFF Research Database (Denmark)

    Bøgh, S.A.; Izadi-Zamanabadi, Roozbeh; Blanke, M.

    1995-01-01

    The increasing operational requirements for onboard autonomy in satellite control systems necessitates structural methods that support the design of a complete and reliable supervisory system.......The increasing operational requirements for onboard autonomy in satellite control systems necessitates structural methods that support the design of a complete and reliable supervisory system....

  5. UAS CNPC Satellite Link Performance - Sharing Spectrum with Terrestrial Systems

    Science.gov (United States)

    Kerczewski, Robert J.; Wilson, Jeffrey D.; Bishop, William D.

    2016-01-01

    In order to provide for the safe integration of unmanned aircraft systems into the National Airspace System, the control and non-payload communications (CNPC) link connecting the ground-based pilot with the unmanned aircraft must be highly reliable. A specific requirement is that it must operate using aviation safety radiofrequency spectrum. The 2012 World Radiocommunication Conference (WRC-12) provided a potentially suitable allocation for radio line-of-sight (LOS), terrestrial based CNPC link at 5030-5091 MHz. For a beyond radio line-of-sight (BLOS), satellite-based CNPC link, aviation safety spectrum allocations are currently inadequate. Therefore, the 2015 WRC will consider the use of Fixed Satellite Service (FSS) bands to provide BLOS CNPC under Agenda Item 1.5. This agenda item requires studies to be conducted to allow for the consideration of how unmanned aircraft can employ FSS for BLOS CNPC while maintaining existing systems. Since there are terrestrial Fixed Service systems also using the same frequency bands under consideration in Agenda Item 1.5 one of the studies required considered spectrum sharing between earth stations on-board unmanned aircraft and Fixed Service station receivers. Studies carried out by NASA have concluded that such sharing is possible under parameters previously established by the International Telecommunications Union. As the preparation for WRC-15 has progressed, additional study parameters Agenda Item 1.5 have been proposed, and some studies using these parameters have been added. This paper examines the study results for the original parameters as well as results considering some of the more recently proposed parameters to provide insight into the complicated process of resolving WRC-15 Agenda Item 1.5 and achieving a solution for BLOS CNPC for unmanned aircraft.

  6. NNIC—neural network image compressor for satellite positioning system

    Science.gov (United States)

    Danchenko, Pavel; Lifshits, Feodor; Orion, Itzhak; Koren, Sion; Solomon, Alan D.; Mark, Shlomo

    2007-04-01

    We have developed an algorithm, based on novel techniques of data compression and neural networks for the optimal positioning of a satellite. The algorithm is described in detail, and examples of its application are given. The heart of this algorithm is the program NNIC—neural network image compressor. This program was developed for compression color and grayscale images with artificial neural networks (ANNs). NNIC applies three different methods for compression. Two of them are based on neural networks architectures—multilayer perceptron and kohonen network. The third is based on a widely used method of discrete cosine transform, the basis for the JPEG standard. The program also serves as a tool for determining numerical and visual quality parameters of compression and comparison between different methods. A number of advantages and disadvantages of the compression using ANNs were discovered in the course of the present research, some of them presented in this report. The thrust of the report is the discussion of ANNs implementation problems for modern platforms, such as a satellite positioning system that include intensive image flowing and processing.

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

    Science.gov (United States)

    Bundrock, Tony; Wilkinson, Mal

    1990-01-01

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

  8. Satellite lines at the ionization threshold in charge transfer systems

    Science.gov (United States)

    Wardermann, W.; von Niessen, W.

    1992-01-01

    This article deals with the possibility of low-energy ionizations of reduced intensity for larger organic molecules. Possible mechanisms which may lead to this phenomenon are outlined and the necessary structural features are discussed. The lowest ionization energies of some organic unsaturated nitro and nitroso compounds are calculated by the ADC(3) ab initio many-body Green's function method. The π-electron system consists either of fused five- and six-membered rings or of two fused five-membered rings with a variable number of heteroatoms. Some of the molecules contain exocylic double bonds and some are substituted with the donor groups -NH 2, -OH and -NHOH. The strongest many-body effects are found for the nitroso compounds, where in one case the spectral line at the ionization threshold has lost more than 40% of its intensity to satellites. We study the many-body effects at or close to the ionization threshold for these compounds. A particular mechanism which involves the screening of localized valence holes by charge transfer excitations appears to be capable of influencing the profile and intensities of the ionization spectrum already at the ionization threshold. The effect leads to strongly reduced relative intensities of the bands and may cause the appearance of satellite bands nearly at the ionization threshold. The spectral changes in the outermost valence region are discussed by using a simple model calculation in terms of ground-state electronic properties of the molecules.

  9. About the Eye

    Medline Plus

    Full Text Available ... Ask a Scientist Video Series Glossary The Visual System Your Eyes’ Natural Defenses Eye Health and Safety First Aid Tips Healthy Vision Tips Protective Eyewear Sports and Your Eyes Fun Stuff Cool Eye Tricks Links to More Information Optical Illusions Printables About the Eye Your eyes ...

  10. About the Eye

    Medline Plus

    Full Text Available ... Ask a Scientist Video Series Glossary The Visual System Your Eyes’ Natural Defenses Eye Health and Safety First Aid Tips Healthy Vision Tips Protective Eyewear Sports and Your Eyes Fun Stuff Cool Eye Tricks Links to More Information Optical Illusions Printables About the Eye Your eyes ...

  11. Design and observations of satellite laser ranging system for daylight tracking at Shanghai Observatory

    Institute of Scientific and Technical Information of China (English)

    杨福民; 肖炽昆; 陈婉珍; 张忠萍; 谭德同; 龚向东; 陈菊平; 黄力; 章建华

    1999-01-01

    The first satellite laser ranging system for daylight tracking in China was set up at Shanghai Observatory, Chinese Academy of Sciences. Both false alarm probability due to strong background noises and detection probability of the laser returns with single photon level from satellite in daylight for our system are analysed. The system design and performance characteristics of subsystems, adopted techniques and satellite ranging observations are given.

  12. PS2013 Satellite Workshop on Photosynthetic Light-Harvesting Systems

    Energy Technology Data Exchange (ETDEWEB)

    Niederman, Robert A. [Rutgers Univ., New Brunswick, NJ (United States); Blankenship, Robert E. [Washington Univ., St. Louis, MO (United States); Frank, Harry A. [Univ. of Connecticut, Storrs, CT (United States)

    2015-02-07

    These funds were used for partial support of the PS2013 Satellite Workshop on Photosynthetic Light-Harvesting Systems, that was held on 8-11 August, 2013, at Washington University, St. Louis, MO. This conference, held in conjunction with the 16th International Congress on Photosynthesis/St. Louis, continued a long tradition of light-harvesting satellite conferences that have been held prior to the previous six international photosynthesis congresses. In this Workshop, the basis was explored for the current interest in replacing fossil fuels with energy sources derived form direct solar radiation, coupled with light-driven electron transport in natural photosynthetic systems and how they offer a valuable blueprint for conversion of sunlight to useful energy forms. This was accomplished through sessions on the initial light-harvesting events in the biological conversion of solar energy to chemically stored energy forms, and how these natural photosynthetic processes serve as a guide to the development of robust bio-hybrid and artificial systems for solar energy conversion into both electricity or chemical fuels. Organized similar to a Gordon Research Conference, a lively, informal and collegial setting was established, highlighting the exchange of exciting new data and unpublished results from ongoing studies. A significant amount of time was set aside for open discussion and interactive poster sessions, with a special session devoted to oral presentations by talented students and postdoctoral fellows judged to have the best posters. This area of research has seen exceptionally rapid progress in recent years, with the availability of a number of antenna protein structures at atomic resolution, elucidation of the molecular surface architecture of native photosynthetic membranes by atomic force microscopy and the maturing of ultrafast spectroscopic and molecular biological techniques for the investigation and manipulation of photosynthetic systems. The conferees

  13. Satellite power system. Concept development and evaluation program

    Energy Technology Data Exchange (ETDEWEB)

    1978-10-01

    The Reference System description emphasizes technical and operational information required in support of environmental, socioeconomic, and comparative assessment studies. Supporting information has been developed according to a guideline of implementing two 5 GW SPS systems per year for 30 years beginning with an initial operational data of 2000 and with SPS's being added at the rate of two per year (10 GW/year) until 2030. The Reference System concept, which features gallium--aluminum--arsenide (GaAlAs) and silicon solar cell options, is described in detail. The concept utilizes a planar solar array (about 55 km/sup 2/) built on a graphite fiber reinforced thermoplastic structure. The silicon array uses a concentration ratio of one (no concentration), whereas the GaAlAs array uses a concentration ratio of two. A one-kilometer diameter phased array microwave antenna is mounted on one end. The antenna uses klystrons as power amplifiers with slotted waveguides as radiating elements. The satellite is constructed in geosynchronous orbit in a six-month period. The ground receiving stations (rectenna) are completed during the same time period. The other two major components of an SPS program are (1) the construction bases in space and launch and mission control bases on earth and (2) fleets of various transportation vehicles that support the construction and maintenance operations of the satellites. These transportation vehicles include Heavy Lift Launch Vehicles (HLLV), Personnel Launch Vehicles (PLV), Cargo Orbit Transfer Vehicles (COTV), and Personnel Orbit Transfer Vehicles (POTV). The earth launch site chosen is the Kennedy Space Center, pending further study.

  14. Satellite Data Assimilation within KIAPS-LETKF system

    Science.gov (United States)

    Jo, Y.; Lee, S., Sr.; Cho, K.

    2016-12-01

    Korea Institute of Atmospheric Prediction Systems (KIAPS) has been developing an ensemble data assimilation system using four-dimensional local ensemble transform kalman filter (LETKF; Hunt et al., 2007) within KIAPS Integrated Model (KIM), referred to as "KIAPS-LETKF". KIAPS-LETKF system was successfully evaluated with various Observing System Simulation Experiments (OSSEs) with NCAR Community Atmospheric Model - Spectral Element (Kang et al., 2013), which has fully unstructured quadrilateral meshes based on the cubed-sphere grid as the same grid system of KIM. Recently, assimilation of real observations has been conducted within the KIAPS-LETKF system with four-dimensional covariance functions over the 6-hr assimilation window. Then, conventional (e.g., sonde, aircraft, and surface) and satellite (e.g., AMSU-A, IASI, GPS-RO, and AMV) observations have been provided by the KIAPS Package for Observation Processing (KPOP). Wind speed prediction was found most beneficial due to ingestion of AMV and for the temperature prediction the improvement in assimilation is mostly due to ingestion of AMSU-A and IASI. However, some degradation in the simulation of the GPS-RO is presented in the upper stratosphere, even though GPS-RO leads positive impacts on the analysis and forecasts. We plan to test the bias correction method and several vertical localization strategies for radiance observations to improve analysis and forecast impacts.

  15. Global Navigation Satellite Systems (GNSS: The Utmost Interdisciplinary Integrator

    Directory of Open Access Journals (Sweden)

    Bernd Eissfeller

    2015-08-01

    Full Text Available Currently four global satellite navigation systems are under modernization and development: The US American GPS III, the Russian GLONASS, the European Galileo and Chinese BeiDou systems. In the paper the interdisciplinary contributions of different scientific areas to GNSS are assessed. It is outlined that GNSS is not only a technical system but also a basic element of mobile computing high-tech market. At the same time a GNSS has the role of a force enabler in security related applications. Technology, market and security policies are interdependent and are sometimes in a relationship of tension. The goal of the paper is to describe the overall systemics of GNSS from a holistic point of view. The paper also addresses the human factor side of GNSS. The requirements on human resources in GNSS are at least two-fold: On the one hand very specialized engineers are needed; on the other hand the generalists are necessary who are able to understand the system aspects. Decision makers in institutions and industry need special knowledge in technologies, economics and political strategies. Is the current university system able to educate and prepare such generalists? Are specialized master courses for GNSS needed? Are external training courses necessary?

  16. About the Eye

    Medline Plus

    Full Text Available ... Glossary The Visual System Your Eyes’ Natural Defenses Eye Health and Safety First Aid Tips Healthy Vision ... to More Information Optical Illusions Printables About the Eye Your eyes are made up of many different ...

  17. About the Eye

    Science.gov (United States)

    ... Glossary The Visual System Your Eyes’ Natural Defenses Eye Health and Safety First Aid Tips Healthy Vision ... to More Information Optical Illusions Printables About the Eye Your eyes are made up of many different ...

  18. Dry Eye

    Science.gov (United States)

    ... Eye > Facts About Dry Eye Facts About Dry Eye This information was developed by the National Eye ... the best person to answer specific questions. Dry Eye Defined What is dry eye? Dry eye occurs ...

  19. Eye Allergies

    Science.gov (United States)

    ... Español Eye Health / Eye Health A-Z Eye Allergies Sections What Are Eye Allergies? Eye Allergy Symptoms ... allergy diagnosis Eye allergy treatment What Are Eye Allergies? Written by: David Turbert Reviewed by: Brenda Pagan- ...

  20. Global tracking and inventory of military hardware via LEO satellite: A system approach and likely scenario

    Science.gov (United States)

    Bell, David; Estabrook, Polly; Romer, Richard

    1995-01-01

    A system for global inventory control of electronically tagged military hardware is achievable using a LEO satellite constellation. An equipment Tag can communicate directly to the satellite with a power of 5 watts or less at a data rate of 2400 to 50,000 bps. As examples, two proposed commercial LEO systems, IRIDIUM and ORBCOMM, are both capable of providing global coverage but with dramatically different telecom capacities. Investigation of these two LEO systems as applied to the Tag scenario provides insight into satellite design trade-offs, constellation trade-offs and signal dynamics that effect the performance of a satellite-based global inventory control system.

  1. DISTANCE MEASURING MODELING AND ERROR ANALYSIS OF DUAL CCD VISION SYSTEM SIMULATING HUMAN EYES AND NECK

    Institute of Scientific and Technical Information of China (English)

    Wang Xuanyin; Xiao Baoping; Pan Feng

    2003-01-01

    A dual-CCD simulating human eyes and neck (DSHEN) vision system is put forward. Its structure and principle are introduced. The DSHEN vision system can perform some movements simulating human eyes and neck by means of four rotating joints, and realize precise object recognizing and distance measuring in all orientations. The mathematic model of the DSHEN vision system is built, and its movement equation is solved. The coordinate error and measure precision affected by the movement parameters are analyzed by means of intersection measuring method. So a theoretic foundation for further research on automatic object recognizing and precise target tracking is provided.

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

    Science.gov (United States)

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

    1986-01-01

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

  3. Tracking wildlife by satellite: Current systems and performance

    Science.gov (United States)

    Harris, Richard B.; Fancy, Steven G.; Douglas, David C.; Garner, Gerald W.; Amstrup, Steven C.; McCabe, Thomas R.; Pank, Larry F.

    1990-01-01

    Since 1984, the U.S. Fish and Wildlife Service has used the Argos Data Collection and Location System (DCLS) and Tiros-N series satellites to monitor movements and activities of 10 species of large mammals in Alaska and the Rocky Mountain region. Reliability of the entire system was generally high. Data were received from instrumented caribou (Rangifer tarandus) during 91% of 318 possible transmitter-months. Transmitters failed prematurely on 5 of 45 caribou, 2 of 6 muskoxen (Ovibos moschatus), and 1 of 2 gray wolves (Canis lupus). Failure rates were considerably higher for polar (Ursus maritimus) and brown (U. arctos) bears than for caribou (Rangifer tarandus). Efficiency of gathering both locational and sensor data was related to both latitude and topography.Mean error of locations was estimated to be 954 m (median = 543 m) for transmitters on captive animals; 90% of locations were <1,732 m from the true location. Argos's new location class zero processing provided many more locations than normal processing, but mean location error was much higher than locations estimated normally. Locations were biased when animals were at elevations other than those used in Argos's calculations.Long-term and short-term indices of animal activity were developed and evaluated. For several species, the long-term index was correlated with movement patterns and the short-term index was calibrated to specific activity categories (e.g., lying, feeding, walking).Data processing and sampling considerations were evaluated. Algorithms for choosing the most reliable among a series of reported locations were investigated. Applications of satellite telemetry data and problems with lack of independence among locations are discussed.

  4. Preliminary Analysis of a Novel SAR Based Emergency System for Earth Orbit Satellites using Galileo

    NARCIS (Netherlands)

    Gill, E.K.A.; Helderweirt, A.

    2010-01-01

    This paper presents a preliminary analysis of a novel Search and Rescue (SAR) based emergency system for Low Earth Orbit (LEO) satellites using the Galileo Global Navigation Satellite System (GNSS). It starts with a description of the space user SAR system including a concept description, mission ar

  5. A general interactive system for compositing digital radar and satellite data

    Science.gov (United States)

    Ghosh, K. K.; Chen, L. C.; Faghmous, M.; Heymsfield, G. M.

    1981-01-01

    Reynolds and Smith (1979) have considered the combined use of digital weather radar and satellite data in interactive systems for case study analysis and forecasting. Satellites view the top of clouds, whereas radar is capable of observing the detailed internal structure of clouds. The considered approach requires the use of a common coordinate system. In the present investigation, it was decided to use the satellite coordinate system as the base system in order to maintain the fullest resolution of the satellite data. The investigation is concerned with the development of a general interactive software system called RADPAK for remapping and analyzing conventional and Doppler radar data. RADPAK is implemented as a part of a minicomputer-based image processing system, called Atmospheric and Oceanographic Image Processing System. Attention is given to a general description of the RADPAK system, remapping methodology, and an example of satellite remapping.

  6. The expression of Mas-receptor of the renin-angiotensin system in the human eye.

    Science.gov (United States)

    Vaajanen, A; Kalesnykas, G; Vapaatalo, H; Uusitalo, H

    2015-07-01

    The local renin-angiotensin system has been held to be expressed in many organs, including the eye. It has an important role in the regulation of local fluid homeostasis, cell proliferation, fibrosis, and vascular tone. Mas-receptor (Mas-R) is a potential receptor acting mainly opposite to the well-known angiotensin II receptor type 1. The aim of this study was to determine if Mas-R is expressed in the human eye. Seven enucleated human eyes were used in immunohistochemical detection of Mas-R and its endogenous ligand angiotensin (1-7) [Ang(1-7)]. Both light microscopy and immunofluorescent detection methods were used. A human kidney preparation sample was used as control. The Mas-R was found to have nuclear localization, and localized in the retinal nuclear layers and in the structures of the anterior segment of the eye. A cytoplasmic immunostaining pattern of Ang(1-7) was found in the inner and outer nuclear and plexiform layers of the retina and in the ciliary body. To the best of our knowledge, this is the first report showing Mas-R expression in the human eye. Its localization suggests that it may have a role in physiological and pathological processes in the anterior part of the eye and in the retina.

  7. The National Polar-orbiting Operational Environmental Satellite System

    Science.gov (United States)

    Bloom, H.

    The tri-agency Integrated Program Office (IPO) is responsible for managing the development of the National Polar-orbiting Operational Environmental Satellite System (NPOESS). NPOESS will replace the current military and civilian operational polar-orbiting ``weather'' satellites. The Northrop Grumman Space Technology - Raytheon team was competitively selected in 2002 as the Acquisition and Operations contractor team to develop, integrate, deploy, and operate NPOESS satellites to meet the tri-agency user requirements for NPOESS over the 10-year (2009-2018) operational life of the program. Beginning in 2009, NPOESS spacecraft will be launched into three orbital planes to provide significantly improved operational capabilities and benefits to satisfy critical civil and national security requirements for space-based, remotely sensed environmental data. With the development of NPOESS, we are evolving operational ``weather'' satellites into integrated environmental observing systems by expanding our capabilities to observe, assess, and predict the total Earth system - atmosphere, ocean, land, and the space environment. In recent years, the operational weather forecasting and climate science communities have levied more rigorous requirements on space-based observations of the Earth's system that have significantly increased demands on performance of the instruments, spacecraft, and ground systems required to deliver NPOESS data, products, and information to end users. The ``end-to-end'' system consists of: the spacecraft; instruments and sensors on the spacecraft; launch support capabilities; the command, control, communications, and data routing infrastructure; and data processing hardware and software. NPOESS will observe significantly more phenomena simultaneously from space than its operational predecessors. NPOESS is expected to deliver large volumes of more accurate measurements at higher spatial (horizontal and vertical) and temporal resolution at much higher data

  8. Gas data transmission system by satellite telephone; Systeme de transmission de donnees sur le gaz utilisant le telephone par satellite

    Energy Technology Data Exchange (ETDEWEB)

    Ogasawara, S.; Tanji, A. [Dengineer Co., Ltd (Japan); Akiyama, S. [Buyo Gas Company (Japan)

    2000-07-01

    Dengineer Co., Ltd. and Buyo Gas Co., Ltd. had been developing and using the data and alarm transmission system by public telephone since 1984, that was first practical use in Japan. It is very important for business management that adjusts the production value of gas by measuring gas pressures in each governor. Also, it is indispensable to know the accident of gas leakage or abnormal gas pressure quickly. But this convenient system is not spread yet in Japanese market cause of the following reasons. - Take time and cost for installation of terminal station. - Terminal station is apt to damage by thunder. - Big disaster must stop working this system. In order to solve those problems, we have developed and tested the system organized of the satellite telephone system and solar cells for power. This system will be very useful for wide place, not only Japanese market but also the area, which has no electricity and phone. Also, it will be convenient for international rescue as is able to access it from the foreign countries. (authors)

  9. FQPSK techniques for satellite and mobile radio communications systems

    Science.gov (United States)

    Li, Yazhuo; Tang, Jing; Tao, Xiaofeng

    2005-11-01

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

  10. Frequency analysis of gaze points with CT colonography interpretation using eye gaze tracking system

    Science.gov (United States)

    Tsutsumi, Shoko; Tamashiro, Wataru; Sato, Mitsuru; Okajima, Mika; Ogura, Toshihiro; Doi, Kunio

    2017-03-01

    It is important to investigate eye tracking gaze points of experts, in order to assist trainees in understanding of image interpretation process. We investigated gaze points of CT colonography (CTC) interpretation process, and analyzed the difference in gaze points between experts and trainees. In this study, we attempted to understand how trainees can be improved to a level achieved by experts in viewing of CTC. We used an eye gaze point sensing system, Gazefineder (JVCKENWOOD Corporation, Tokyo, Japan), which can detect pupil point and corneal reflection point by the dark pupil eye tracking. This system can provide gaze points images and excel file data. The subjects are radiological technologists who are experienced, and inexperienced in reading CTC. We performed observer studies in reading virtual pathology images and examined observer's image interpretation process using gaze points data. Furthermore, we examined eye tracking frequency analysis by using the Fast Fourier Transform (FFT). We were able to understand the difference in gaze points between experts and trainees by use of the frequency analysis. The result of the trainee had a large amount of both high-frequency components and low-frequency components. In contrast, both components by the expert were relatively low. Regarding the amount of eye movement in every 0.02 second we found that the expert tended to interpret images slowly and calmly. On the other hand, the trainee was moving eyes quickly and also looking for wide areas. We can assess the difference in the gaze points on CTC between experts and trainees by use of the eye gaze point sensing system and based on the frequency analysis. The potential improvements in CTC interpretation for trainees can be evaluated by using gaze points data.

  11. A Ku-band satellite system for the cable television industry

    Science.gov (United States)

    Napoli, Joseph

    This paper describes the satellite requirements for the Ku-band used for satellite delivery of television programming. The case for using the Ku-band is reviewed, including the business benefits to the cable industry, the superior protection against failure, the pace of technical advances, and the channel capacity. The characteristics of the satellites carrying the Ku-band are described, and a protection plan for the satellites is considered. The technical characteristics of the Ku-band and related systems considerations are addressed. Signal outage at the Ku-band is discussed, and Ku-band receiving system design is examined, including system installation and operations.

  12. A MEO Tracking and Data Relay Satellite System Constellation Scheme for China

    Institute of Scientific and Technical Information of China (English)

    WU Ting-yong; WU Shi-qi; LING Xiang

    2005-01-01

    A medium earth orbit (MEO) tracking and data relay satellite system (TDRSS) constellation scheme for China is proposed. This system consists of MEO satellite constellation, inter-satellite links (ISLs) and terrestrial gateway station, which can provide continuous bidirectional data transmission links between low altitude spacecrafts and the terrestrial gateway station in China. Theoretical analysis and simulation results indicate that the proposed constellation can cover the global low altitude space sphere and earth surface of China continuously, and has a preferable practical perspective.

  13. Three-dimensional system integration for HUD placement on a new tactical airlift platform: design eye point vs. HUD eye box with accommodation and perceptual implications

    Science.gov (United States)

    Harbour, Steven D.; Hudson, Jeffery A.; Zehner, Gregory F.

    2012-06-01

    The retrofitting of a cockpit with a Head-Up-Display (HUD) raises potential accommodation and perceptual issues for pilots that must be addressed. For maximum optical efficiency, the goal is to be able to place every pilot's eye into the HUD Eye Motion Box (EMB) given a seat adjustment range. Initially, the Eye Reference Point (ERP) of the EMB should theoretically be located on the aircraft's original cockpit Design Eye Point (DEP), but human postures vary, and HUD systems may not be optimally placed. In reality, there is a distribution of pilot eyes around the DEP (which is dominant eye dependent); therefore, this must be accounted for in order to obtain appropriate visibility of all of the symbology based on photonic characteristics of the HUD. Pilot size and postural variation need to be taken into consideration when positioning the HUD system to ensure proper vision of all HUD symbology in addition to meeting the basic physical accommodation requirements of the cockpit. The innovative process and data collection methods for maximizing accommodation and pilot perception on a new "tactical airlift" platform are discussed as well as the related neurocognitive factors and the effects of information display design on cognitive phenomena.

  14. Adaptive beamforming in a CDMA mobile satellite communications system

    Science.gov (United States)

    Munoz-Garcia, Samuel G.

    1993-01-01

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

  15. Design of an Eye Limiting Resolution Visual System Using Commercial-Off-the-Shelf Equipment

    Science.gov (United States)

    Sweet, Barbara T.; Giovannetti, Dean P.

    2008-01-01

    A feasibility study was conducted to determine if a flight simulator with an eye-limiting resolution out-the-window (OTW) visual system could be built using commercial off-the-shelf (COTS) technology and used to evaluate the visual performance of Air Force pilots in an operations context. Results of this study demonstrate that an eye limiting OTW visual system can be built using COTS technology. Further, a series of operationally-based tasks linked to clinical vision tests can be used within the synthetic environment to demonstrate a correlation and quantify the level of correlation between vision and operational aviation performance.

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

    Science.gov (United States)

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

    1995-01-01

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

  17. Deep Charging Evaluation of Satellite Power and Communication System Components

    Science.gov (United States)

    Schneider, T. A.; Vaughn, J. A.; Chu, B.; Wong, F.; Gardiner, G.; Wright, K. H.; Phillips, B.

    2016-01-01

    Deep charging, in contrast to surface charging, focuses on electron penetration deep into insulating materials applied over conductors. A classic example of this scenario is an insulated wire. Deep charging can pose a threat to material integrity, and to sensitive electronics, when it gives rise to an electrostatic discharge or arc. With the advent of Electric Orbit Raising, which requires spiraling through Earth's radiation belts, satellites are subjected to high energy electron environments which they normally would not encounter. Beyond Earth orbit, missions to Jupiter and Saturn face deep charging concerns due to the high energy radiation environments. While predictions can be made about charging in insulating materials, it is difficult to extend those predictions to complicated geometries, such as the case of an insulating coating around a small wire, or a non-uniform silicone grouting on a bus bar. Therefore, to conclusively determine the susceptibility of a system to arcs from deep charging, experimental investigations must be carried out. This paper will describe the evaluation carried out by NASA's Marshall Space Flight Center on subscale flight-like samples developed by Space Systems/Loral, LLC. Specifically, deep charging evaluations of solar array wire coupons, a photovoltaic cell coupon, and a coaxial microwave transmission cable, will be discussed. The results of each evaluation will be benchmarked against control sample tests, as well as typical power system levels, to show no significant deep charging threat existed for this set of samples under the conditions tested.

  18. Comparing the Zeiss Callisto Eye and the Alcon Verion Image Guided System Toric Lens Alignment Technologies.

    Science.gov (United States)

    Hura, Arjan S; Osher, Robert H

    2017-07-01

    To compare the alignment meridian generated by the Zeiss Callisto Eye (Carl Zeiss AG, Dublin, CA) and the Alcon Verion Image Guided System (Alcon Laboratories, Inc., Fort Worth, TX). In this retrospective comparative evaluation of technology, intraoperative images were captured at different steps in the same surgery, allowing the comparison of the guidance lines generated by the Verion system to the parallel guidance lines generated by the Callisto Eye system. Measurements of each hemi-meridian were quantified using Adobe Photoshop 2015 CC software (Adobe Systems, San Jose, CA). The numbers of degrees separating these alignment meridians were calculated, entered into a database, and analyzed. The authors found that of 98 captured images of 16 eyes, the two technologies were identical in 0 eyes (θ1 = θ2 = 0), similar by 3° in 52 (53%) captured images (θ1 ≠ θ2 ≠ 0), and different by at least 3° in 46 (47%) captured images (θ1 ≠ θ2 ≠ 0). The target meridians were superimposed, the target lines were minimally separated, and the target lines were dissimilar. It was noted that some intraoperative variation occurred from measurement to measurement. Within the small group of 16 cases of routine toric lens implantation in this study, the absolute average number of degrees of misalignment between the Verion and Callisto Eye systems was 3.355 for θ1 and 3.838 for θ2. On average, the intraoperative variation termed "drift" was noted to be 3.963° for θ1, and 4.557° for θ2. The authors found that small deviations were frequent when comparing two sophisticated technologies. Although deviations greater than 3° occurred in less than 47% of captured images from 16 eyes, smaller but significant variations of less than 3° occurred in 53% of captured images from 16 eyes. It was rare to identify a large deviation. However, the authors identified "drift" in the same eye when measurements were taken at different times. The results indicate that the two systems are

  19. Design of object surveillance system based on enhanced fish-eye lens

    Institute of Scientific and Technical Information of China (English)

    Jianhui Wu; Kuntao Yang; Qiaolian Xiang; Nanyang Zhang

    2009-01-01

    A new method is proposed for the object surveillance system based on the enhanced fish-eye lens and the high speed digital signal processor (DSP). The improved fish-eye lens images an ellipse picture on the charge-coupled device (CCD) surface, which increases both the utilization rate of the 4:3 rectangular CCD and the imaging resolution, and remains the view angle of 183°. The algorithm of auto-adapted renewal background subtraction (ARBS) is also explored to extract the object from the monitoring image. The experimental result shows that the ARBS algorithm has high anti-jamming ability and high resolution, leading to excellent object detecting ability from the enhanced elliptical fish-eye image under varies en-vironments. This system has potential applications in different security monitoring fields due to its wide monitoring space, simple structure, working stability, and reliability.

  20. Impulse processing: a dynamical systems model of incremental eye movements in the visual world paradigm.

    Science.gov (United States)

    Kukona, Anuenue; Tabor, Whitney

    2011-08-01

    The Visual World Paradigm (VWP) presents listeners with a challenging problem: They must integrate two disparate signals, the spoken language and the visual context, in support of action (e.g., complex movements of the eyes across a scene). We present Impulse Processing, a dynamical systems approach to incremental eye movements in the visual world that suggests a framework for integrating language, vision, and action generally. Our approach assumes that impulses driven by the language and the visual context impinge minutely on a dynamical landscape of attractors corresponding to the potential eye-movement behaviors of the system. We test three unique predictions of our approach in an empirical study in the VWP, and describe an implementation in an artificial neural network. We discuss the Impulse Processing framework in relation to other models of the VWP.

  1. Integration System of Head, Eye, and Retinal Position Signals for Perceptual Direction

    Science.gov (United States)

    Yamaguchi, Masashi; Kaneko, Hirohiko

    2007-11-01

    This study investigates the integration system of head (-to-trunk), eye (-to-head), and retinal position signals for hand pointing. In experiment 1, subjects changed their head and eye positions and pointed at a fixated visual stimulus by using an unseen pointer. In experiment 2, subjects fixated a visual stimulus and pointed at another visual stimulus. The results show that the head and eye position signals contributed linearly to perceptual direction (experiments 1 and 2), and that the coefficients of these signals decrease with peripheral vision and are smaller than the coefficient of the retinal position signal (experiment 2). These results collectively suggest that the integration algorithm of the position signals might be described by the linear summation equation and that the retinal position signal serves a more important role than the other position signals in the visual system.

  2. Impulse processing: A dynamical systems model of incremental eye movements in the visual world paradigm

    Science.gov (United States)

    Kukona, Anuenue; Tabor, Whitney

    2011-01-01

    The visual world paradigm presents listeners with a challenging problem: they must integrate two disparate signals, the spoken language and the visual context, in support of action (e.g., complex movements of the eyes across a scene). We present Impulse Processing, a dynamical systems approach to incremental eye movements in the visual world that suggests a framework for integrating language, vision, and action generally. Our approach assumes that impulses driven by the language and the visual context impinge minutely on a dynamical landscape of attractors corresponding to the potential eye-movement behaviors of the system. We test three unique predictions of our approach in an empirical study in the visual world paradigm, and describe an implementation in an artificial neural network. We discuss the Impulse Processing framework in relation to other models of the visual world paradigm. PMID:21609355

  3. Advanced payload concepts and system architecture for emerging services in Indian National Satellite Systems

    Science.gov (United States)

    Balasubramanian, E. P.; Rao, N. Prahlad; Sarkar, S.; Singh, D. K.

    2008-07-01

    Over the past two decades Indian Space Research Organization (ISRO) has developed and operationalized satellites to generate a large capacity of transponders for telecommunication service use in INSAT system. More powerful on-board transmitters are built to usher-in direct-to-home broadcast services. These have transformed the Satcom application scenario in the country. With the proliferation of satellite technology, a shift in the Indian market is witnessed today in terms of demand for new services like Broadband Internet, Interactive Multimedia, etc. While it is imperative to pay attention to market trends, ISRO is also committed towards taking the benefits of technological advancement to all round growth of our population, 70% of which dwell in rural areas. The initiatives already taken in space application related to telemedicine, tele-education and Village Resource Centres are required to be taken to a greater height of efficiency. These targets pose technological challenges to build a large capacity and cost-effective satellite system. This paper addresses advanced payload concepts and system architecture along with the trade-off analysis on design parameters in proposing a new generation satellite system capable of extending the reach of the Indian broadband structure to individual users, educational and medical institutions and enterprises for interactive services. This will be a strategic step in the evolution of INSAT system to employ advanced technology to touch every human face of our population.

  4. FORMATION OF MULTIPLE-SATELLITE SYSTEMS FROM LOW-MASS CIRCUMPLANETARY PARTICLE DISKS

    Energy Technology Data Exchange (ETDEWEB)

    Hyodo, Ryuki; Ohtsuki, Keiji [Department of Earth and Planetary Sciences, Kobe University, Kobe 657-8501 (Japan); Takeda, Takaaki, E-mail: ryukih@stu.kobe-u.ac.jp, E-mail: ohtsuki@tiger.kobe-u.ac.jp [VASA Entertainment Co. Ltd. (Japan)

    2015-01-20

    Circumplanetary particle disks would be created in the late stage of planetary formation either by impacts of planetary bodies or disruption of satellites or passing bodies, and satellites can be formed by accretion of disk particles spreading across the Roche limit. Previous N-body simulation of lunar accretion focused on the formation of single-satellite systems from disks with large disk-to-planet mass ratios, while recent models of the formation of multiple-satellite systems from disks with smaller mass ratios do not take account of gravitational interaction between formed satellites. In the present work, we investigate satellite accretion from particle disks with various masses, using N-body simulation. In the case of accretion from somewhat less massive disks than the case of lunar accretion, formed satellites are not massive enough to clear out the disk, but can become massive enough to gravitationally shepherd the disk outer edge and start outward migration due to gravitational interaction with the disk. When the radial location of the 2:1 mean motion resonance of the satellite reaches outside the Roche limit, the second satellite can be formed near the disk outer edge, and then the two satellites continue outward migration while being locked in the resonance. Co-orbital satellites are found to be occasionally formed on the orbit of the first satellite. Our simulations also show that stochastic nature involved in gravitational interaction and collision between aggregates in the tidal environment can lead to diversity in the final mass and orbital architecture, which would be expected in satellite systems of exoplanets.

  5. Joint Polar Satellite System (JPSS) Common Ground System (CGS) Current Technical Performance Measures

    Science.gov (United States)

    Cochran, S.; Panas, M.; Jamilkowski, M. L.; Miller, S. W.

    2015-12-01

    ABSTRACT The National Oceanic and Atmospheric Administration (NOAA) and National Aeronautics and Space Administration (NASA) are jointly acquiring the next-generation civilian weather and environmental satellite system: the Joint Polar Satellite System (JPSS). The Joint Polar Satellite System will replace the afternoon orbit component and ground processing system of the current Polar-orbiting Operational Environmental Satellites (POES) managed by NOAA. The JPSS satellites will carry a suite of sensors designed to collect meteorological, oceanographic, climatological and geophysical observations of the Earth. The ground processing system for JPSS is known as the JPSS Common Ground System (JPSS CGS). Developed and maintained by Raytheon Intelligence, Information and Services (IIS), the CGS is a multi-mission enterprise system serving NOAA, NASA and their national and international partners. The CGS has demonstrated its scalability and flexibility to incorporate multiple missions efficiently and with minimal cost, schedule and risk, while strengthening global partnerships in weather and environmental monitoring. The CGS architecture is being upgraded to Block 2.0 in 2015 to "operationalize" S-NPP, leverage lessons learned to date in multi-mission support, take advantage of more reliable and efficient technologies, and satisfy new requirements and constraints in the continually evolving budgetary environment. To ensure the CGS meets these needs, we have developed 49 Technical Performance Measures (TPMs) across 10 categories, such as data latency, operational availability and scalability. This paper will provide an overview of the CGS Block 2.0 architecture, with particular focus on the 10 TPM categories listed above. We will provide updates on how we ensure the deployed architecture meets these TPMs to satisfy our multi-mission objectives with the deployment of Block 2.0.

  6. Satellite Power System (SPS) FY 79 Program Summary

    Energy Technology Data Exchange (ETDEWEB)

    1980-01-01

    The Satellite Power System (SPS) program is a joint effort of the US Department of Energy (DOE) and the National Aeronautics and Space Administration (NASA). It is managed by the SPS Project Office within DOE's Office of Energy Research. SPS project organization is shown in Figure 1. The SPS Project Office was established in 1978 and is responsible for the planning, management and integration of SPS research in four areas: systems definition, environmental assessment, societal assessment, and comparative assessment. In fulfilling its responsibilities, the SPS Project Office directs research and assessment efforts to determine the feasibility of the SPS concept, funds organizations supporting the program, and disseminates information developed from project research and assessments. The objective of the SPS program is to develop an initial understanding of the technical feasibility, the economic practicality, and the social and environmental acceptability of the SPS concept. This is being accomplished through implementation of the Concept Development and Evaluation Program Plan which is scheduled for completion by the end of FY 1980. The SPS Project Office annually issues a Program Summary which describes the research undertaken during the preceding fiscal year. This Program Summary covers FY 1979. It includes work completed in FY 1977 and FY 1978 in order to give a comprehensive picture of the DOE involvement in the SPS concept development and evaluation process.

  7. SMART-T: a system for novel fully automated anticipatory eye-tracking paradigms.

    Science.gov (United States)

    Shukla, Mohinish; Wen, Johnny; White, Katherine S; Aslin, Richard N

    2011-06-01

    Anticipatory eye movements (AEMs) are a natural and implicit measure of cognitive processing and have been successfully used to document such important cognitive capacities as learning, categorization, and generalization, especially in infancy (McMurray & Aslin, Infancy, 6, 203-229, 2004). Here, we describe an improved AEM paradigm to automatically assess online learning on a trial-by-trial basis, by analyzing eye gaze data in each intertrial interval of a training phase. Different measures of learning can be evaluated simultaneously. We describe the implementation of a system for designing and running a variety of such AEM paradigms. Additionally, this system is capable of a wider variety of gaze-contingent paradigms, as well as implementations of standard noncontingent paradigms. Our system, Smart-T (System for Monitoring Anticipations in Real Time with the Tobii), is a set of MATLAB scripts with a graphical front end, written using the Psychophysics Toolbox. The system gathers eye gaze data using the commercially available Tobii eye-trackers via a MATLAB module, Talk2Tobii. We report a pilot study showing that Smart-T can detect 6-month-old infants' learning of simple predictive patterns involving the disappearance and reappearance of multimodal stimuli.

  8. Research on the image fusion and target extraction based on bionic compound eye system

    Science.gov (United States)

    Zhang, Shaowei; Hao, Qun; Song, Yong; Wang, Zihan; Zhang, Kaiyu; Zhang, Shiyu

    2015-08-01

    People attach more and more importance to bionic compound eye due to its advantages such as small volume, large field of view and sensitivity to high-speed moving objects. Small field of view and large volume are the disadvantages of traditional image sensor and in order to avoid these defects, this paper intends to build a set of compound eye system based on insect compound eye structure and visual processing mechanism. In the center of this system is the primary sensor which has high resolution ratio. The primary sensor is surrounded by the other six sensors which have low resolution ratio. Based on this system, this paper will study the target image fusion and extraction method by using plane compound eye structure. This paper designs a control module which can combine the distinguishing features of high resolution image with local features of low resolution image so as to conduct target detection, recognition and location. Compared with traditional ways, the way of high resolution in the center and low resolution around makes this system own the advantages of high resolution and large field of view and enables the system to detect the object quickly and recognize the object accurately.

  9. A Positioning System based on Communication Satellites and the Chinese Area Positioning System (CAPS)

    Science.gov (United States)

    Ai, Guo-Xiang; Shi, Hu-Li; Wu, Hai-Tao; Yan, Yi-Hua; Bian, Yu-Jing; Hu, Yong-Hui; Li, Zhi-Gang; Guo, Ji; Xian-DeCai

    2008-12-01

    The Chinese Area Positioning System (CAPS) is a positioning system based on satellite communication that is fundamentally different from the 3``G'' (GPS, GLONASS and GALILEO) systems. The latter use special-purpose navigation satellites to broadcast navigation information generated on-board to users, while the CAPS transfers ground-generated navigation information to users via the communication satellite. In order to achieve accurate Positioning, Velocity and Time (PVT), the CAPS employs the following strategies to overcome the three main obstacles caused by using the communication satellite: (a) by real-time following-up frequency stabilization to achieve stable frequency; (b) by using a single carrier in the transponder with 36 MHz band-width to gain sufficient power; (c) by incorporating Decommissioned Geostationary Orbit communication satellite (DGEO), barometric pressure and Inclined Geostationary Orbit communication satellite (IGSO) to achieve the 3-D positioning. Furthermore, the abundant transponders available on DGEO can be used to realize the large capacity of communication as well as the integrated navigation and communication. With the communication functions incorporated, five new functions appear in the CAPS: (1) combination of navigation and communication; (2) combination of navigation and high accuracy orbit measurement; (3) combination of navigation message and wide/local area differential processing; (4) combination of the switching of satellites, frequencies and codes; and (5) combination of the navigation message and the barometric altimetry. The CAPS is thereby labelled a PVT5C system of high accuracy. In order to validate the working principle and the performance of the CAPS, a trial system was established in the course of two years at a cost of about 20 million dollars. The trial constellation consists of two GEO satellites located at E87.5° and E110.5°, two DGEOs located at E130° and E142°, as well as barometric altimetry as a virtual

  10. A Positioning System based on Communication Satellites and the Chinese Area Positioning System (CAPS)

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    The Chinese Area Positioning System (CAPS) is a positioning system based on satellite communication that is fundamentally different from the 3"G" (GPS, GLONASS and GALILEO) systems. The latter use special-purpose navigation satellites to broadcast navi-gation information generated on-board to users, while the CAPS transfers ground-generated navigation information to users via the communication satellite. In order to achieve accurate Positioning, Velocity and Time (PVT), the CAPS employs the following strategies to over-come the three main obstacles caused by using the communication satellite: (a) by real-time following-up frequency stabilization to achieve stable frequency; (b) by using a single carrier in the transponder with 36 MHz band-width to gain sufficient power; (c) by incorporating Decommissioned Geostationary Orbit communication satellite (DGEO), barometric pressure and Inclined Geostationary Orbit communication satellite (IGSO) to achieve the 3-D posi-tioning. Furthermore, the abundant transponders available on DGEO can be used to realize the large capacity of communication as well as the integrated navigation and communication. With the communication functions incorporated, five new functions appear in the CAPS: (1) combination of navigation and communication; (2) combination of navigation and high accu-racy orbit measurement; (3) combination of navigation message and wide/local area differen-tial processing; (4) combination of the switching of satellites, frequencies and codes; and (5) combination of the navigation message and the barometric altimetry. The CAPS is thereby labelled a PVT5C system of high accuracy. In order to validate the working principle and the performance of the CAPS, a trial system was established in the course of two years at a cost of about 20 million dollars. The trial constellation consists of two GEO satellites located at E87.5°and E110.5°, two DGEOs located at E130° and E142°, as well as barometric altimetry as a virtual

  11. A classification system for virophages and satellite viruses.

    Science.gov (United States)

    Krupovic, Mart; Kuhn, Jens H; Fischer, Matthias G

    2016-01-01

    Satellite viruses encode structural proteins required for the formation of infectious particles but depend on helper viruses for completing their replication cycles. Because of this unique property, satellite viruses that infect plants, arthropods, or mammals, as well as the more recently discovered satellite-like viruses that infect protists (virophages), have been grouped with other, so-called "sub-viral agents." For the most part, satellite viruses are therefore not classified. We argue that possession of a coat-protein-encoding gene and the ability to form virions are the defining features of a bona fide virus. Accordingly, all satellite viruses and virophages should be consistently classified within appropriate taxa. We propose to create four new genera - Albetovirus, Aumaivirus, Papanivirus, and Virtovirus - for positive-sense single-stranded (+) RNA satellite viruses that infect plants and the family Sarthroviridae, including the genus Macronovirus, for (+)RNA satellite viruses that infect arthopods. For double-stranded DNA virophages, we propose to establish the family Lavidaviridae, including two genera, Sputnikvirus and Mavirus.

  12. iDEAS: A web-based system for dry eye assessment.

    Science.gov (United States)

    Remeseiro, Beatriz; Barreira, Noelia; García-Resúa, Carlos; Lira, Madalena; Giráldez, María J; Yebra-Pimentel, Eva; Penedo, Manuel G

    2016-07-01

    Dry eye disease is a public health problem, whose multifactorial etiology challenges clinicians and researchers making necessary the collaboration between different experts and centers. The evaluation of the interference patterns observed in the tear film lipid layer is a common clinical test used for dry eye diagnosis. However, it is a time-consuming task with a high degree of intra- as well as inter-observer variability, which makes the use of a computer-based analysis system highly desirable. This work introduces iDEAS (Dry Eye Assessment System), a web-based application to support dry eye diagnosis. iDEAS provides a framework for eye care experts to collaboratively work using image-based services in a distributed environment. It is composed of three main components: the web client for user interaction, the web application server for request processing, and the service module for image analysis. Specifically, this manuscript presents two automatic services: tear film classification, which classifies an image into one interference pattern; and tear film map, which illustrates the distribution of the patterns over the entire tear film. iDEAS has been evaluated by specialists from different institutions to test its performance. Both services have been evaluated in terms of a set of performance metrics using the annotations of different experts. Note that the processing time of both services has been also measured for efficiency purposes. iDEAS is a web-based application which provides a fast, reliable environment for dry eye assessment. The system allows practitioners to share images, clinical information and automatic assessments between remote computers. Additionally, it save time for experts, diminish the inter-expert variability and can be used in both clinical and research settings. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

  13. Automatic system for 3D reconstruction of the chick eye based on digital photographs.

    Science.gov (United States)

    Wong, Alexander; Genest, Reno; Chandrashekar, Naveen; Choh, Vivian; Irving, Elizabeth L

    2012-01-01

    The geometry of anatomical specimens is very complex and accurate 3D reconstruction is important for morphological studies, finite element analysis (FEA) and rapid prototyping. Although magnetic resonance imaging, computed tomography and laser scanners can be used for reconstructing biological structures, the cost of the equipment is fairly high and specialised technicians are required to operate the equipment, making such approaches limiting in terms of accessibility. In this paper, a novel automatic system for 3D surface reconstruction of the chick eye from digital photographs of a serially sectioned specimen is presented as a potential cost-effective and practical alternative. The system is designed to allow for automatic detection of the external surface of the chick eye. Automatic alignment of the photographs is performed using a combination of coloured markers and an algorithm based on complex phase order likelihood that is robust to noise and illumination variations. Automatic segmentation of the external boundaries of the eye from the aligned photographs is performed using a novel level-set segmentation approach based on a complex phase order energy functional. The extracted boundaries are sampled to construct a 3D point cloud, and a combination of Delaunay triangulation and subdivision surfaces is employed to construct the final triangular mesh. Experimental results using digital photographs of the chick eye show that the proposed system is capable of producing accurate 3D reconstructions of the external surface of the eye. The 3D model geometry is similar to a real chick eye and could be used for morphological studies and FEA.

  14. System Design and In-orbit Verification of the HJ-1-C SAR Satellite

    OpenAIRE

    Zhang Run-ning; Jiang Xiu-peng

    2014-01-01

    HJ-1-C is a SAR satellite owned by the Chinese Environment and Natural Disaster Monitoring constellation, and works together with the optical satellites HJ-1-A/B for monitoring environment and natural disasters. In this paper, the system design and characteristics of the first Chinese civil SAR satellite are described. In addition, the interface relation between SAR payload and platform is studied. Meanwhile, the data transmission capability, attitude, power, and temperature control that supp...

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

    Science.gov (United States)

    Hart, Nicholas; Goerke, Thomas; Jahn, Axel

    1995-01-01

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

  16. Ground Simulation of an Autonomous Satellite Rendezvous and Tracking System Using Dual Robotic Systems

    Science.gov (United States)

    Trube, Matthew J.; Hyslop, Andrew M.; Carignan, Craig R.; Easley, Joseph W.

    2012-01-01

    A hardware-in-the-loop ground system was developed for simulating a robotic servicer spacecraft tracking a target satellite at short range. A relative navigation sensor package "Argon" is mounted on the end-effector of a Fanuc 430 manipulator, which functions as the base platform of the robotic spacecraft servicer. Machine vision algorithms estimate the pose of the target spacecraft, mounted on a Rotopod R-2000 platform, relay the solution to a simulation of the servicer spacecraft running in "Freespace", which performs guidance, navigation and control functions, integrates dynamics, and issues motion commands to a Fanuc platform controller so that it tracks the simulated servicer spacecraft. Results will be reviewed for several satellite motion scenarios at different ranges. Key words: robotics, satellite, servicing, guidance, navigation, tracking, control, docking.

  17. Excitation of inclinations in ring-satellite systems

    Science.gov (United States)

    Borderies, N.; Goldreich, P.; Tremaine, S.

    1984-01-01

    Resonant gravitational interactions between a ring and a satellite produce secular variations of their orbital inclinations. Interactions at vertical resonances, analogous to Lindblad resonances but involving inclinations instead of eccentricities, excite inclinations. There is no inclination analog of the corotation resonance. An equatorial ring changes the inclination of a nearby satellite in qualitatively the same way that a satellite in an equatorial orbit changes the inclination of a nearby ring. Viscous dissipation in a ring leads to an equilibrium value of its inclination. These results provide a basis for discussing the origins of the inclinations of planetary rings.

  18. Multichannel demultiplexer/demodulator technologies for future satellite communication systems

    Science.gov (United States)

    Ivancic, William D.; Budinger, James M.; Staples, Edward J.; Abramovitz, Irwin; Courtois, Hector A.

    1992-01-01

    NASA-Lewis' Space Electronics Div. supports ongoing research in advanced satellite communication architectures, onboard processing, and technology development. Recent studies indicate that meshed VSAT (very small aperture terminal) satellite communication networks using FDMA (frequency division multiple access) uplinks and TDMA (time division multiplexed) downlinks are required to meet future communication needs. One of the critical advancements in such a satellite communication network is the multichannel demultiplexer/demodulator (MCDD). The progress is described which was made in MCDD development using either acousto-optical, optical, or digital technologies.

  19. Development of Instrument Control System Using Biosignals Created by the Change of Eyes Movement Sequence

    Institute of Scientific and Technical Information of China (English)

    XIAO Yun-xiang(肖云翔); LI Gang(李刚); NOGATA Fumio

    2003-01-01

    A new biosignal control system that offers the disables the opportunities to control electric appliances is proposed. The four types of signals created by the eyes movements in four directions ( up, down, left, and right) ,which are taken as four basic signals, are detected at the forehead. Permutation of 2 signals out of them creates 16 different signals. Permutation of 3 signals out of them creates 64 signals. They all amounts to 84 control signals. They are thought to be applicable for the operation of some instruments. Furthermore, the dynamic biosignals created by the slow eyes movement is speculated to be applicable for the more convenient control of them.

  20. MEMS scanner mirror based system for retina scanning and in eye projection

    Science.gov (United States)

    Woittennek, Franziska; Knobbe, Jens; Pügner, Tino; Dallmann, Hans-Georg; Schelinski, Uwe; Grüger, Heinrich

    2015-02-01

    Many applications could benefit from miniaturized systems to scan blood vessels behind the retina in the human eye, so called "retina scanning". This reaches from access control to sophisticated security applications and medical devices. High volume systems for consumer applications require low cost and a user friendly operation. For example this includes no need for removal of glasses and self-adjustment, in turn guidance of focus and point of attraction by simultaneous projection for the user. A new system has been designed based on the well-known resonantly driven 2-d scanner mirror of Fraunhofer IPMS. A combined NIR and VIS laser system illuminates the eye through an eye piece designed for an operating distance allowing the use of glasses and granting sufficient field of view. This usability feature was considered to be more important than highest miniaturization. The modulated VIS laser facilitates the projection of an image directly onto the retina. The backscattered light from the continuous NIR laser contains the information of the blood vessels and is detected by a highly sensitive photo diode. A demonstrational setup has been realized including readout and driving electronics. The laser power was adjusted to an eye-secure level. Additional security features were integrated. Test measurements revealed promising results. In a first demonstration application the detection of biometric pattern of the blood vessels was evaluated for issues authentication in.

  1. G-MAP: a novel night vision system for satellites

    Science.gov (United States)

    Miletti, Thomas; Maresi, Luca; Zuccaro Marchi, Alessandro; Pontetti, Giorgia

    2015-10-01

    The recent developments of single-photon counting array detectors opens the door to a novel type of systems that could be used on satellites in low Earth orbit. One possible application is the detection of non-cooperative vessels or illegal fishing activities. Currently only surveillance operations conducted by Navy or coast guard address this topic, operations by nature costly and with limited coverage. This paper aims to describe the architectural design of a system based on a novel single-photon counting detector, which works mainly in the visible and features fast readout, low noise and a 256x256 matrix of 64 μm-pixels. This detector is positioned in the focal plane of a fully aspheric reflective f/6 telescope, to guarantee state of the art performance. The combination of the two grants optimal ground sampling distance, compatible with the average dimension of a vessel, and overall performance. A radiative analysis of the light transmitted from emission to detection is presented, starting from models of lamps used for attracting fishes and illuminating the deck of the boats. A radiative transfer model is used to estimate the amount of photons emitted by such vessels reaching the detector. Since the novel detector features high framerate and low noise, the system as it is envisaged is able to properly serve the proposed goal. The paper shows the results of a trade-off between instrument parameters and spacecraft operations to maximize the detection probability and the covered sea surface. The status of development of both detector and telescope are also described.

  2. Classification of Satellite Resonances in the Solar System

    Science.gov (United States)

    Luan, Jing; Goldreich, Peter

    2017-01-01

    Several pairs of solar system satellites occupy mean motion resonances (MMRs). We divide these into two groups according to their proximity to exact resonance. Proximity is measured by the existence of a separatrix in phase space. MMRs between Io–Europa, Europa–Ganymede, and Enceladus–Dione are too distant from exact resonance for a separatrix to appear. A separatrix is present only in the phase spaces of the Mimas–Tethys and Titan–Hyperion MMRs, and their resonant arguments are the only ones to exhibit substantial librations. Could there be a causal connection between the libration amplitude and the presence of a separatrix? Our suspicions were aroused by Goldreich & Schlichting, who demonstrate that sufficiently deep in a MMR, eccentricity damping could destabilize librations. However, our investigation reveals that libration amplitudes in both the Mimas–Tethys and Titan–Hyperion MMRs are fossils. Although the Mimas–Tethys MMR is overstable, its libration amplitude grows on the tidal damping timescale of Mimas’s inclination, which is considerably longer than a Hubble time. On the other hand, the Titan–Hyperion MMR is stable, but tidal damping of Hyperion’s eccentricity is too weak to have affected the amplitude of its libration.

  3. Fates of satellite ejecta in the Saturn system, II

    Science.gov (United States)

    Alvarellos, José Luis; Dobrovolskis, Anthony R.; Zahnle, Kevin J.; Hamill, Patrick; Dones, Luke; Robbins, Stuart

    2017-03-01

    We assess the fates of ejecta from the large craters Aeneas on Dione and Ali Baba on Enceladus (161 and 39 km in diameter, respectively), as well as that from Herschel (130 km in diameter) on Mimas. The ejecta are treated either as 'spalls' launched from hard surfaces, or as 'rubble' launched from a weak rubble pile regolith. Once in orbit we consider the ejecta as massless test particles subject to the gravity of Saturn and its classical satellites. The great majority of escaped ejecta get swept up by the source moons. The best fit to the ejecta population decay is a stretched exponential with exponent near 1/2 (Dobrovolskis et al., Icarus 188, 481-505, 2007). We bracket the characteristic ejecta sizes corresponding to Grady-Kipp fragments and spalls. Based on this and computed impact velocities and incidence angles, the resulting sesquinary craters, if they exist, should have diameters on the order of a few meters to a few km. The observed longitude distribution of small craters on Mimas along with the findings of Bierhaus et al. that small moons should not have a secondary crater population (Icarus 218, 602-621, 2012) suggest that the most likely place to find sesquinary craters in the Saturn system is the antapex of Mimas.

  4. Evaluating Silent Reading Performance with an Eye Tracking System in Patients with Glaucoma

    Science.gov (United States)

    Murata, Noriaki; Fukuchi, Takeo

    2017-01-01

    Objective To investigate the relationship between silent reading performance and visual field defects in patients with glaucoma using an eye tracking system. Methods Fifty glaucoma patients (Group G; mean age, 52.2 years, standard deviation: 11.4 years) and 20 normal controls (Group N; mean age, 46.9 years; standard deviation: 17.2 years) were included in the study. All participants in Group G had early to advanced glaucomatous visual field defects but better than 20/20 visual acuity in both eyes. Participants silently read Japanese articles written horizontally while the eye tracking system monitored and calculated reading duration per 100 characters, number of fixations per 100 characters, and mean fixation duration, which were compared with mean deviation and visual field index values from Humphrey visual field testing (24–2 and 10–2 Swedish interactive threshold algorithm standard) of the right versus left eye and the better versus worse eye. Results There was a statistically significant difference between Groups G and N in mean fixation duration (G, 233.4 msec; N, 215.7 msec; P = 0.010). Within Group G, significant correlations were observed between reading duration and 24–2 right mean deviation (rs = -0.280, P = 0.049), 24–2 right visual field index (rs = -0.306, P = 0.030), 24–2 worse visual field index (rs = -0.304, P = 0.032), and 10–2 worse mean deviation (rs = -0.326, P = 0.025). Significant correlations were observed between mean fixation duration and 10–2 left mean deviation (rs = -0.294, P = 0.045) and 10–2 worse mean deviation (rs = -0.306, P = 0.037), respectively. Conclusions The severity of visual field defects may influence some aspects of reading performance. At least concerning silent reading, the visual field of the worse eye is an essential element of smoothness of reading. PMID:28095478

  5. The coordinate system of the eye in cataract surgery: Performance comparison of the circle Hough transform and Daugman's algorithm

    Science.gov (United States)

    Vlachynska, Alzbeta; Oplatkova, Zuzana Kominkova; Sramka, Martin

    2017-07-01

    The aim of the work is to determine the coordinate system of an eye and insert a polar-axis system into images captured by a slip lamp. The image of the eye with the polar axis helps a surgeon accurately implant toric intraocular lens in the required position/rotation during the cataract surgery. In this paper, two common algorithms for pupil detection are compared: the circle Hough transform and Daugman's algorithm. The procedures were tested and analysed on the anonymous data set of 128 eyes captured at Gemini eye clinic in 2015.

  6. Multifunctional astronomical self-organizing system of autonomous navigation and orientation for artificial Earth satellites

    Science.gov (United States)

    Kuznetsov, V. I.; Danilova, T. V.

    2017-03-01

    We describe the methods and algorithms of a multifunctional astronomical system of the autonomous navigation and orientation for artificial Earth satellites based on the automatization of the system approach to the design and programming problems of the subject area.

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

    Science.gov (United States)

    Ringer, Mark J.

    1994-01-01

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

  8. Defining and representing events in a satellite scheduling system - The IEPS (Interactive Experimenter Planning System) approach

    Science.gov (United States)

    McLean, David R.; Littlefield, Ronald G.; Macoughtry, William O.

    A methodology is described for defining and representing satellite events from the IEPS perspective. The task of doing this is divided into four categories and includes defining and representing resource windows, event parameters, event scheduling strategies, and event constraints. The description of each of these categories includes examples from the IEPS ERBS-TDRSS Contact Planning System. This is a system which is being used by the Earth Radiation Budget Satellite (ERBS) schedulers to request TDRSS contact times from the NCC. The system is written in the C programming language and uses a custom built inference engine (TIE1) to do constraint checking and a custom built strategies interpreter to derive the plan. The planning system runs on the IBM-PC/AT or on any similar hardware which has a C development environment and 640K of memory.

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

    Science.gov (United States)

    Ananasso, F.; Mistretta, I.

    1992-03-01

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

  10. Simulated human eye retina adaptive optics imaging system based on a liquid crystal on silicon device

    Institute of Scientific and Technical Information of China (English)

    Jiang Bao-Guang; Cao Zhao-Liang; Mu Quan-Quan; Hu Li-Fa; Li Chao; Xuan Li

    2008-01-01

    In order to obtain a clear image of the retina of model eye, an adaptive optics system used to correct the wave-front error is introduced in this paper. The spatial light modulator that we use here is a liquid crystal on a silicon device instead of a conversional deformable mirror. A paper with carbon granule is used to simulate the retina of human eye. The pupil size of the model eye is adjustable (3-7 mm). A Shack-Hartman wave-front sensor is used to detect the wave-front aberration. With this construction, a value of peak-to-valley is achieved to be 0.086 λ, where A is wavelength.The modulation transfer functions before and after corrections are compared. And the resolution of this system after correction (691p/m) is very close to the diffraction limit resolution. The carbon granule on the white paper which has a size of 4.7μm is seen clearly. The size of the retina cell is between 4 and 10 μm. So this system has an ability to image the human eye's retina.

  11. Eclectic Ocular Comorbidities and Systemic Diseases with Eye Involvement: A Review

    Directory of Open Access Journals (Sweden)

    María D. Pinazo-Durán

    2016-01-01

    Full Text Available Coexistence of several ocular diseases is more frequent than suspected. In spite of the refractive errors, one or more of the following can be detected simultaneously: glaucoma, cataracts, uveitis, age-related macular degeneration, and dry eyes. In addition, as people age, ocular comorbidities are much more usually seen. Specific diseases are openly acknowledged to affect the eyes and vision, such as diabetes mellitus, hypertension blood pressure, arthritis, hyperthyroidism, neurodegenerative disorders, hematologic malignancies, and/or systemic infections. Recent advances in early diagnosis and therapy of the ophthalmic pathologies have reinforced patient options to prevent visual impairment and blindness. Because of this, it is essential not to overlook sight-threatening conditions such as the ocular comorbidities and/or the eye involvement in the context of systemic disorders. Moreover, the important role of the multidisciplinary cooperation to improve and sustain management of patients affected with eclectic ocular comorbidities and/or systemic disorders with eye repercussion is specifically addressed. This review intends to shed light on these topics to help in making opportune diagnosis and appropriately managing the affected patients.

  12. Higher order aberrations comparison in fellow eyes following intraLase LASIK with wavelight allegretto and customcornea LADArvision4000 systems.

    Science.gov (United States)

    Tran, Dan B; Shah, Viraj

    2006-11-01

    To compare the differences in objective and subjective visual outcomes with wavefront-optimized versus wavefront-guided excimer laser ablations using two different excimer laser platforms. In this prospective, randomized, matched, contralateral eye study, one eye was treated with the Alcon CustomCornea system, and the fellow eye was treated with the WaveLight Allegretto Wavefront-Optimized system. The IntraLase FS30 femtosecond laser was used to create all flaps. Treatments were randomized to the dominant eye, and optical treatment zones were matched to 6.5 mm. Patients were observed for 3 months after surgery. Initial data analysis was available for the first 28 eyes of 14 patients. The only statistically significant differences between the groups were seen in the amount of higher order aberrations-the 14 eyes in the WaveLight group had a mean preoperative root-mean-square (RMS) error of 0.37 microm compared to 0.36 microm for 14 eyes in the Alcon group. Of the 8 patients who had 3-month follow-up, 8 eyes in the WaveLight group had a mean RMS error of 0.58 microm at 3 months, compared to 0.41 microm in the 8 eyes in the Alcon group. Early results from this study have shown that both laser platforms produce accurate refractive outcomes; however, the Alcon CustomCornea LADARVision4000 system induces statistically significantly fewer higher order aberrations than the WaveLight Allegretto system.

  13. The integrated satellite-acoustic telemetry (iSAT) system for tracking marine megafauna

    KAUST Repository

    De La Torre, Pedro R.

    2012-10-06

    This document describes the integrated satellite-acoustic telemetry (iSAT) system: an autonomous modular system for tracking the movements of large pelagic fish using acoustic telemetry and satellite communications. The sensor platform is described along with the propulsion and navigation systems. An application for tracking the whale shark (Rhincodon typus) in the Red Sea is included along with a discussion of the technical difficulties that such a system faces.

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

    Science.gov (United States)

    Vatalaro, F.; Losquadro, G.

    1995-01-01

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

  15. A comparing design of satellite attitude control system based on reaction wheel

    Institute of Scientific and Technical Information of China (English)

    CHENG Hao; GE Sheng-min; SHEN Yi

    2008-01-01

    The disturbance caused by the reaction wheel with a current controller greatly influences the accuracy and stability of the satellite attitude control system.To solve this problem,the idea of speed feedback compensation control reaction wheel is put forward.This paper introduces the comparison on design and performance of two satellite attitude control systems,which are separately based on the current control reaction wheel and the speed feedback compensation control reaction wheel.Analysis shows that the speed feedback compensation control flywheel system may effectively suppress the torque fluctuation.Simulation results indicate that the satellite attitude control system with the speed feedback compensation control flywheel has improved performance.

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

    Science.gov (United States)

    Arcidiancono, Antonio

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

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

    Science.gov (United States)

    Arcidiancono, Antonio

    1990-01-01

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

  18. Europa Jupiter System Mission (EJSM): Exploration Of The Jovian System And Its Icy Satellites

    Science.gov (United States)

    Grasset, Olivier; Pappalardo, R.; Greeley, R.; Blanc, M.; Dougherty, M.; Bunce, E.; Lebreton, J.; Prockter, L.; Senske, D.; EJSM Joint Science Definition Team

    2009-09-01

    The Europa Jupiter System Mission (EJSM) would be an international mission with the overall theme of investigating the emergence of habitable worlds around gas giants. Its goals are to (1) Determine whether the Jupiter system harbors habitable worlds and (2) Characterize the processes that are operating within the Jupiter system. NASA and ESA have concluded a detailed joint study of a mission to Europa, Ganymede, and the Jupiter system with orbiters developed by NASA and ESA (future contributions by JAXA and Russia are also possible). The baseline EJSM architecture consists of two primary elements operating in the Jovian system: the NASA-led Jupiter Europa Orbiter (JEO), and the ESA-led Jupiter Ganymede Orbiter (JGO). JEO and JGO would execute an intricately choreographed exploration of the Jupiter System before settling into orbit around Europa and Ganymede, respectively. EJSM would directly address themes concerning the origin and evolution of satellite systems and water-rich environments in icy satellites. The potential habitability of the ocean-bearing moons Europa and Ganymede would be investigated, by characterizing the geophysical, compositional, geological, and external processes that affect these icy worlds. EJSM would also investigate Io and Callisto, Jupiter's atmosphere, and the Jovian magnetosphere. By understanding the Jupiter system and unraveling its history, the formation and evolution of gas giant planets and their satellites would be better known. Most important, EJSM would shed new light on the potential for the emergence of life in the celestial neighborhood and beyond. The EJSM architecture provides opportunities for coordinated synergistic observations by JEO and JGO of the Jupiter and Ganymede magnetospheres, the volcanoes and torus of Io, the atmosphere of Jupiter, and comparative planetology of icy satellites. Each spacecraft would conduct both synergistic dual-spacecraft investigations and "stand-alone” measurements.

  19. Microfluidic separation of satellite droplets as the basis of a monodispersed micron and submicron emulsification system.

    Science.gov (United States)

    Tan, Yung-Chieh; Lee, Abraham Phillip

    2005-10-01

    Emulsions are widely used to produce sol-gel, drugs, synthetic materials, and food products. Recent advancements in microfluidic droplet emulsion technology has enabled the precise sampling and processing of small volumes of fluids (picoliter to femtoliter) by the controlled viscous shearing in microchannels. However the generation of monodispersed droplets smaller than 1 microm without surfactants has been difficult to achieve. Normally, the generation of satellite droplets along with parent droplets is undesirable and makes it difficult to control volume and purity of samples in droplets. In this paper, however, several methods are presented to passively filter out satellite droplets from the generation of parent droplets and use these satellite droplets as the source for monodispersed production of submicron emulsions. A passive satellite droplet filtration system and a dynamic satellite droplet separation system are demonstrated. Satellite droplets are filtered from parent droplets with a two-layer channel geometry. This design allows the creation and collection of droplets that are less than 100 nm in diameter. In the dynamic separation system, satellite droplets of defined sizes can be selectively separated into different collecting zones. The separation of the satellite droplets into different collecting zones correlates with the cross channel position of the satellite droplets during the breakup of the liquid thread. The delay time for droplets to switch between the different alternating collecting zones is nominally 1 min and is proportional to the ratio of the oil shear flows. With our droplet generation system, monodispersed satellite droplets with an average radius of 2.23 +/- 0.11 microm, and bidispersed secondary and tertiary satellite droplets with radii of 1.55 +/- 0.07 microm and 372 +/- 46 nm respectively, have been dynamically separated and collected.

  20. Design and simulation of satellite attitude control system based on Simulink and VR

    Science.gov (United States)

    Zhang, Yang; Gan, Qingbo; Kang, Jingshu

    2016-01-01

    In order to research satellite attitude control system design and visual simulation, the simulation framework of satellite dynamics and attitude control using Simulink were established. The design of satellite earth-oriented control system based on quaternion feedback was completed. The 3D scene based on VR was created and models in the scene were driven by simulation data of Simulink. By coordinate transformation. successful observing the scene in inertial coordinate system, orbit coordinate system and body coordinate system. The result shows that application of simulation method of Simulink combined with VR in the design of satellite attitude control system field, has the advantages of high confidence level, hard real-time property, multi-perspective and multi-coordinate system observing the scene, and improves the comprehensibility and accuracy of the design.

  1. Dutch Micro Systems Technology for the Next Generation of Small Satellites

    NARCIS (Netherlands)

    Gill, E.; Monna, G.L.E.; Scherpen, J.M.A.; Verhoeven, C.J.M.

    2007-01-01

    Advanced microelectronics and Micro Systems Technology (MST) enable an increased functional performance of small satellites with decreased demands on mass, size and power. The research and development cluster MISAT stimulates the design and development of advanced small satellite platforms based on

  2. Dutch Micro Systems Technology for the Next Generation of Small Satellites

    NARCIS (Netherlands)

    Gill, E.; Monna, G.L.E.; Scherpen, J.M.A.; Verhoeven, C.J.M.

    2007-01-01

    Advanced microelectronics and Micro Systems Technology (MST) enable an increased functional performance of small satellites with decreased demands on mass, size and power. The research and development cluster MISAT stimulates the design and development of advanced small satellite platforms based on

  3. Application of a regularized model inversion system (REGFLEC) to multi-temporal RapidEye imagery for retrieving vegetation characteristics

    Science.gov (United States)

    Houborg, Rasmus; McCabe, Matthew F.

    2015-10-01

    Accurate retrieval of canopy biophysical and leaf biochemical constituents from space observations is critical to diagnosing the functioning and condition of vegetation canopies across spatio-temporal scales. Retrieved vegetation characteristics may serve as important inputs to precision farming applications and as constraints in spatially and temporally distributed model simulations of water and carbon exchange processes. However significant challenges remain in the translation of composite remote sensing signals into useful biochemical, physiological or structural quantities and treatment of confounding factors in spectrum-trait relations. Bands in the red-edge spectrum have particular potential for improving the robustness of retrieved vegetation properties. The development of observationally based vegetation retrieval capacities, effectively constrained by the enhanced information content afforded by bands in the red-edge, is a needed investment towards optimizing the benefit of current and future satellite sensor systems. In this study, a REGularized canopy reFLECtance model (REGFLEC) for joint leaf chlorophyll (Chll) and leaf area index (LAI) retrieval is extended to sensor systems with a band in the red-edge region for the first time. Application to time-series of 5 m resolution multi-spectral RapidEye data is demonstrated over an irrigated agricultural region in central Saudi Arabia, showcasing the value of satellite-derived crop information at this fine scale for precision management. Validation against in-situ measurements in fields of alfalfa, Rhodes grass, carrot and maize indicate improved accuracy of retrieved vegetation properties when exploiting red-edge information in the model inversion process.

  4. Application of a regularized model inversion system (REGFLEC) to multi-temporal RapidEye imagery for retrieving vegetation characteristics

    KAUST Repository

    Houborg, Rasmus

    2015-10-14

    Accurate retrieval of canopy biophysical and leaf biochemical constituents from space observations is critical to diagnosing the functioning and condition of vegetation canopies across spatio-temporal scales. Retrieved vegetation characteristics may serve as important inputs to precision farming applications and as constraints in spatially and temporally distributed model simulations of water and carbon exchange processes. However significant challenges remain in the translation of composite remote sensing signals into useful biochemical, physiological or structural quantities and treatment of confounding factors in spectrum-trait relations. Bands in the red-edge spectrum have particular potential for improving the robustness of retrieved vegetation properties. The development of observationally based vegetation retrieval capacities, effectively constrained by the enhanced information content afforded by bands in the red-edge, is a needed investment towards optimizing the benefit of current and future satellite sensor systems. In this study, a REGularized canopy reFLECtance model (REGFLEC) for joint leaf chlorophyll (Chll) and leaf area index (LAI) retrieval is extended to sensor systems with a band in the red-edge region for the first time. Application to time-series of 5 m resolution multi-spectral RapidEye data is demonstrated over an irrigated agricultural region in central Saudi Arabia, showcasing the value of satellite-derived crop information at this fine scale for precision management. Validation against in-situ measurements in fields of alfalfa, Rhodes grass, carrot and maize indicate improved accuracy of retrieved vegetation properties when exploiting red-edge information in the model inversion process. © (2015) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE).

  5. Mimicking honeybee eyes with a 280{sup 0} field of view catadioptric imaging system

    Energy Technology Data Exchange (ETDEWEB)

    Stuerzl, W; Boeddeker, N; Dittmar, L; Egelhaaf, M, E-mail: wolfgang.stuerzl@uni-bielefeld.d [Department of Neurobiology and Center of Excellence ' Cognitive Interaction Technology' , Bielefeld University (Germany)

    2010-09-15

    We present a small single camera imaging system that provides a continuous 280{sup 0} field of view (FOV) inspired by the large FOV of insect eyes. This is achieved by combining a curved reflective surface that is machined into acrylic glass with lenses covering the frontal field that otherwise would have been obstructed by the mirror. Based on the work of Seidl (1982 PhD Thesis Technische Hochschule Darmstadt), we describe an extension of the 'bee eye optics simulation' (BEOS) model by Giger (1996 PhD Thesis Australian National University) to the full FOV which enables us to remap camera images according to the spatial resolution of honeybee eyes. This model is also useful for simulating the visual input of a bee-like agent in a virtual environment. The imaging system in combination with our bee eye model can serve as a tool for assessing the visual world from a bee's perspective which is particularly helpful for experimental setups. It is also well suited for mobile robots, in particular on flying vehicles that need light-weight sensors.

  6. Satellite Power Systems (SPS) concept definition study. Volume 2, part 2: System engineering

    Science.gov (United States)

    Hanley, G. M.

    1980-09-01

    The latest technical and programmatic developments are considered as well as expansions of the Rockwell SPS cost model covering each phase of the program through the year 2030. Comparative cost/economic analyses cover elements of the satellite, construction system, space transportation vehicles and operations, and the ground receiving station. System plans to define time phased costs and planning requirements that support major milestones through the year 2000. A special analysis is included on natural resources required to build the SPS reference configuration. An appendix contains the SPS Work Breakdown Structure and dictionary along with detail cost data sheet on each system and main element of the program. Over 200 line items address DDT&E, theoretical first unit, investment cost per satellite, and operations charges for replacement capital and normal operations and maintenance costs.

  7. Satellite Power Systems (SPS) concept definition study. Volume 2, part 2: System engineering. [cost and programmatics

    Science.gov (United States)

    Hanley, G. M.

    1980-01-01

    The latest technical and programmatic developments are considered as well as expansions of the Rockwell SPS cost model covering each phase of the program through the year 2030. Comparative cost/economic analyses cover elements of the satellite, construction system, space transportation vehicles and operations, and the ground receiving station. System plans to define time phased costs and planning requirements that support major milestones through the year 2000. A special analysis is included on natural resources required to build the SPS reference configuration. An appendix contains the SPS Work Breakdown Structure and dictionary along with detail cost data sheet on each system and main element of the program. Over 200 line items address DDT&E, theoretical first unit, investment cost per satellite, and operations charges for replacement capital and normal operations and maintenance costs.

  8. The Saturn System Through the Eyes of Cassini

    Science.gov (United States)

    Green, James

    2017-01-01

    More than 400 years ago, Galileo Galilei trained his homemade telescope on the night sky and observed that Saturn had two objects closely related to the planet extending on either side. At the time, in 1610, Galileo declared them to be moons. A few decades later, Saturn moon science accelerated at a dizzying pace. Christiaan Huygens first observed Saturn's largest moon Titan in 1655 and was the first to describe the extended moon-like features at Saturn as a disk of material sounding the planet. From 1671 to 1674, Giovanni Cassini discovered the moons lapetus, Rhea, Dione and Tethys. In 1675, Cassini discovered the gap in Saturn's rings that we now know as the Cassini Division. In the space age, before the Cassini-Huygens mission, we had only hints of the discoveries awaiting us at Saturn. Pioneer 11 and Voyagers 1 and 2 conducted flybys decades ago. But these quick encounters didn't allow time for more extensive research. NASA and the European Space Agency created a partnership to orbit a Saturn orbiter (Cassini) and a lander (Huygens) on Titan. Like its namesakes, the Cassini-Huygens mission not only discovered previously unknown moons, but it also helped us understand the science behind their formation, their interactions with the rings, and how truly diverse they are. The Cassini-Huygens mission revolutionized what we know about the Saturn system. The rings of Saturn, the moons, and the planet itself offer irresistible and inexhaustible subjects for intense study, and Cassini-Huygens did not disappoint. The Saturnian system proved to be a rich ground for science exploration and discoveries, and Cassini has been nothing short of a discovery machine. At the time Cassini plunged into Saturn at the end of its mission, it had observed the planet for a little less than half of a Saturn year. But it also orbited the gas giant 293 times, forever changing our understanding of the Saturn system and yielding tremendous insight for understanding the entire Solar System.

  9. Monte Carlo simulations of precise timekeeping in the Milstar communication satellite system

    Science.gov (United States)

    Camparo, James C.; Frueholz, R. P.

    1995-01-01

    The Milstar communications satellite system will provide secure antijam communication capabilities for DOD operations into the next century. In order to accomplish this task, the Milstar system will employ precise timekeeping on its satellites and at its ground control stations. The constellation will consist of four satellites in geosynchronous orbit, each carrying a set of four rubidium (Rb) atomic clocks. Several times a day, during normal operation, the Mission Control Element (MCE) will collect timing information from the constellation, and after several days use this information to update the time and frequency of the satellite clocks. The MCE will maintain precise time with a cesium (Cs) atomic clock, synchronized to UTC(USNO) via a GPS receiver. We have developed a Monte Carlo simulation of Milstar's space segment timekeeping. The simulation includes the effects of: uplink/downlink time transfer noise; satellite crosslink time transfer noise; satellite diurnal temperature variations; satellite and ground station atomic clock noise; and also quantization limits regarding satellite time and frequency corrections. The Monte Carlo simulation capability has proven to be an invaluable tool in assessing the performance characteristics of various timekeeping algorithms proposed for Milstar, and also in highlighting the timekeeping capabilities of the system. Here, we provide a brief overview of the basic Milstar timekeeping architecture as it is presently envisioned. We then describe the Monte Carlo simulation of space segment timekeeping, and provide examples of the simulation's efficacy in resolving timekeeping issues.

  10. 77 FR 51045 - Certain Two-Way Global Satellite Communication Devices, System and Components Thereof; Notice of...

    Science.gov (United States)

    2012-08-23

    ... COMMISSION Certain Two-Way Global Satellite Communication Devices, System and Components Thereof; Notice of... Commission has received a complaint entitled Certain Two-Way Global Satellite Communication Devices, System... satellite communication devices, systems. The complaint names as respondents Delorme Publishing Company Inc...

  11. Cat-eye target imaging system research and dual-channel DSP implementation

    Science.gov (United States)

    Zheng, Zheng; Zhang, Haiyang; Shi, Guang; Han, Lei; Zhao, Changming

    2013-09-01

    In modern warfare, well-equipped and trained snipers have become a mortal malady for the combat troops. How to accurately, timely and quickly find and destroy snipers becomes a research focus of national military experts. In order to effectively detect faint echo signal of cat-eye target and get the snipers' position information in the detection area, a small size of dual-channel active laser detection system with monochrome and color Charge-couple Devices(CCD) is designed, which is based on the laser imaging principle of cat-eye effect, associated tests are also conducted. The dual-channel video capture can obtain more information of target area, while taking advantage of the high sensitivity of monochrome CCD will also provide more accurate grayscale information for the video image processing. In order to achieve the miniaturization of system, we choose a video processing board whose size is only 54mm*90mm as hardware platform to complete the algorithm. For verifying the feasibility and accuracy of algorithm, we ultimately build a full set of experimental detection system. The test results show that the system can accurately detect and mark typical cat-eye target from background under different distances, which verifies the rationality and validity of the proposed system and has certain practicality and promotion in the active laser detection system research areas.

  12. Preliminary environmental assessment for the satellite power system (SPS). Revision 1. Volume 1. Executive summary

    Energy Technology Data Exchange (ETDEWEB)

    1980-01-01

    A preliminary assessment of the environmental impacts of the proposed satellite power system (SPS) is summarized here. In this system, satellites would collect solar energy in space, convert it to microwaves, and transmit the microwaves to receiving antennas (rectennas) on earth. At the rectennas, the microwaves would be converted to electricity. The assessment considers microwave and nonmicrowave effects on the terrestrial environment and human health, atmospheric effects, and disruption of communications and other electromagnetic systems.

  13. The Minnesota Grading System Using Fundus Autofluorescence of Eye Bank Eyes: A Correlation To Age-Related Macular Degeneration (An AOS Thesis)

    Science.gov (United States)

    Olsen, Timothy W.

    2008-01-01

    Purpose To establish a grading system of eye bank eyes using fundus autofluorescence (FAF) and identify a methodology that correlates FAF to age-related macular degeneration (AMD) with clinical correlation to the Age-Related Eye Disease Study (AREDS). Methods Two hundred sixty-two eye bank eyes were evaluated using a standardized analysis of FAF. Measurements were taken with the confocal scanning laser ophthalmoscope (cSLO). First, high-resolution, digital, stereoscopic, color images were obtained and graded according to AREDS criteria. With the neurosensory retina removed, mean FAF values were obtained from cSLO images using software analysis that excludes areas of atrophy and other artifact, generating an FAF value from a grading template. Age and AMD grade were compared to FAF values. An internal fluorescence reference standard was tested. Results Standardization of the cSLO machine demonstrated that reliable data could be acquired after a 1-hour warm-up. Images obtained prior to 1 hour had falsely elevated levels of FAF. In this initial analysis, there was no statistical correlation of age to mean FAF. There was a statistically significant decrease in FAF from AREDS grade 1, 2 to 3, 4 (P < .0001). An internal fluorescent standard may serve as a quantitative reference. Conclusions The Minnesota Grading System (MGS) of FAF (MGS-FAF) establishes a standardized methodology for grading eye bank tissue to quantify FAF compounds in the retinal pigment epithelium and correlate these findings to the AREDS. Future studies could then correlate specific FAF to the aging process, histopathology AMD phenotypes, and other maculopathies, as well as to analyze the biochemistry of autofluorescent fluorophores. PMID:19277247

  14. Comprehensive Comparisons of Satellite Data, Signals, and Measurements between the BeiDou Navigation Satellite System and the Global Positioning System.

    Science.gov (United States)

    Jan, Shau-Shiun; Tao, An-Lin

    2016-05-13

    The Chinese BeiDou navigation satellite system (BDS) aims to provide global positioning service by 2020. The combined use of BDS and Global Positioning System (GPS) is proposed to provide navigation service with more stringent requirements. Actual satellite data, signals and measurements were collected for more than one month to analyze the positioning service qualities from both BDS and GPS. In addition to the conversions of coordinate and timing system, five data quality analysis (DQA) methods, three signal quality analysis (SQA) methods, and four measurement quality analysis (MQA) methods are proposed in this paper to improve the integrated positioning performance of BDS and GPS. As shown in the experiment results, issues related to BDS and GPS are resolved by the above proposed quality analysis methods. Thus, the anomalies in satellite data, signals and measurements can be detected by following the suggested resolutions to enhance the positioning performance of the combined use of BDS and GPS in the Asia Pacific region.

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

    Science.gov (United States)

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

    1993-01-01

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

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

    Science.gov (United States)

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

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

  17. Eye redness

    Science.gov (United States)

    Bloodshot eyes; Red eyes; Scleral injection; Conjunctival injection ... There are many causes of a red eye or eyes. Some are medical emergencies. Others are a cause for concern, but not an emergency. Many are nothing to worry about. Eye ...

  18. A novel approach for simulating the optical misalignment caused by satellite platform vibration in the ground test of satellite optical communication systems.

    Science.gov (United States)

    Wang, Qiang; Tan, Liying; Ma, Jing; Yu, Siyuan; Jiang, Yijun

    2012-01-16

    Satellite platform vibration causes the misalignment between incident direction of the beacon and optical axis of the satellite optical communication system, which also leads to the instability of the laser link and reduces the precision of the system. So how to simulate the satellite platform vibration is a very important work in the ground test of satellite optical communication systems. In general, a vibration device is used for simulating the satellite platform vibration, but the simulation effect is not ideal because of the limited randomness. An approach is reasonable, which uses a natural random process for simulating the satellite platform vibration. In this paper, we discuss feasibility of the concept that the effect of angle of arrival fluctuation is taken as an effective simulation of satellite platform vibration in the ground test of the satellite optical communication system. Spectrum characteristic of satellite platform vibration is introduced, referring to the model used by the European Space Agency (ESA) in the SILEX program and that given by National Aeronautics and Space Development Agency (NASDA) of Japan. Spectrum characteristic of angle of arrival fluctuation is analyzed based on the measured data from an 11.16km bi-directional free space laser transmission experiment. Spectrum characteristic of these two effects is compared. The results show that spectra of these two effects have similar variation trend with the variation of frequency and feasibility of the concept is proved by the comparison results. At last the procedure of this method is proposed, which uses the power spectra of angle of arrival fluctuation to simulate that of the satellite platform vibration. The new approach is good for the ground test of satellite optical communication systems.

  19. Introducing multisensor satellite radiance-based evaluation for regional Earth System modeling

    Science.gov (United States)

    Matsui, T.; Santanello, J.; Shi, J. J.; Tao, W.-K.; Wu, D.; Peters-Lidard, C.; Kemp, E.; Chin, M.; Starr, D.; Sekiguchi, M.; Aires, F.

    2014-07-01

    Earth System modeling has become more complex, and its evaluation using satellite data has also become more difficult due to model and data diversity. Therefore, the fundamental methodology of using satellite direct measurements with instrumental simulators should be addressed especially for modeling community members lacking a solid background of radiative transfer and scattering theory. This manuscript introduces principles of multisatellite, multisensor radiance-based evaluation methods for a fully coupled regional Earth System model: NASA-Unified Weather Research and Forecasting (NU-WRF) model. We use a NU-WRF case study simulation over West Africa as an example of evaluating aerosol-cloud-precipitation-land processes with various satellite observations. NU-WRF-simulated geophysical parameters are converted to the satellite-observable raw radiance and backscatter under nearly consistent physics assumptions via the multisensor satellite simulator, the Goddard Satellite Data Simulator Unit. We present varied examples of simple yet robust methods that characterize forecast errors and model physics biases through the spatial and statistical interpretation of various satellite raw signals: infrared brightness temperature (Tb) for surface skin temperature and cloud top temperature, microwave Tb for precipitation ice and surface flooding, and radar and lidar backscatter for aerosol-cloud profiling simultaneously. Because raw satellite signals integrate many sources of geophysical information, we demonstrate user-defined thresholds and a simple statistical process to facilitate evaluations, including the infrared-microwave-based cloud types and lidar/radar-based profile classifications.

  20. Introducing Multisensor Satellite Radiance-Based Evaluation for Regional Earth System Modeling

    Science.gov (United States)

    Matsui, T.; Santanello, J.; Shi, J. J.; Tao, W.-K.; Wu, D.; Peters-Lidard, C.; Kemp, E.; Chin, M.; Starr, D.; Sekiguchi, M.; hide

    2014-01-01

    Earth System modeling has become more complex, and its evaluation using satellite data has also become more difficult due to model and data diversity. Therefore, the fundamental methodology of using satellite direct measurements with instrumental simulators should be addressed especially for modeling community members lacking a solid background of radiative transfer and scattering theory. This manuscript introduces principles of multisatellite, multisensor radiance-based evaluation methods for a fully coupled regional Earth System model: NASA-Unified Weather Research and Forecasting (NU-WRF) model. We use a NU-WRF case study simulation over West Africa as an example of evaluating aerosol-cloud-precipitation-land processes with various satellite observations. NU-WRF-simulated geophysical parameters are converted to the satellite-observable raw radiance and backscatter under nearly consistent physics assumptions via the multisensor satellite simulator, the Goddard Satellite Data Simulator Unit. We present varied examples of simple yet robust methods that characterize forecast errors and model physics biases through the spatial and statistical interpretation of various satellite raw signals: infrared brightness temperature (Tb) for surface skin temperature and cloud top temperature, microwave Tb for precipitation ice and surface flooding, and radar and lidar backscatter for aerosol-cloud profiling simultaneously. Because raw satellite signals integrate many sources of geophysical information, we demonstrate user-defined thresholds and a simple statistical process to facilitate evaluations, including the infrared-microwave-based cloud types and lidar/radar-based profile classifications.

  1. Real-Time Orbit Determination for Future Korean Regional Navigation Satellite System

    Science.gov (United States)

    Shin, Kihae; Oh, Hyungjik; Park, Sang-Young; Park, Chandeok

    2016-03-01

    This paper presents an algorithm for Real-Time Orbit Determination (RTOD) of navigation satellites for the Korean Regional Navigation Satellite System (KRNSS), when the navigation satellites generate ephemeris by themselves in abnormal situations. The KRNSS is an independent Regional Navigation Satellite System (RNSS) that is currently within the basic/preliminary research phase, which is intended to provide a satellite navigation service for South Korea and neighboring countries. Its candidate constellation comprises three geostationary and four elliptical inclined geosynchronous orbit satellites. Relative distance ranging between the KRNSS satellites based on Inter-Satellite Ranging (ISR) is adopted as the observation model. The extended Kalman filter is used for real-time estimation, which includes fine-tuning the covariance, measurement noise, and process noise matrices. Simulation results show that ISR precision of 0.3-0.7 m, ranging capability of 65,000 km, and observation intervals of less than 20 min are required to accomplish RTOD accuracy to within 1 m. Furthermore, close correlation is confirmed between the dilution of precision and RTOD accuracy.

  2. Video-Based Eye Tracking to Detect the Attention Shift: A Computer Classroom Context-Aware System

    Science.gov (United States)

    Kuo, Yung-Lung; Lee, Jiann-Shu; Hsieh, Min-Chai

    2014-01-01

    Eye and head movements evoked in response to obvious visual attention shifts. However, there has been little progress on the causes of absent-mindedness so far. The paper proposes an attention awareness system that captures the conditions regarding the interaction of eye gaze and head pose under various attentional switching in computer classroom.…

  3. Video-Based Eye Tracking to Detect the Attention Shift: A Computer Classroom Context-Aware System

    Science.gov (United States)

    Kuo, Yung-Lung; Lee, Jiann-Shu; Hsieh, Min-Chai

    2014-01-01

    Eye and head movements evoked in response to obvious visual attention shifts. However, there has been little progress on the causes of absent-mindedness so far. The paper proposes an attention awareness system that captures the conditions regarding the interaction of eye gaze and head pose under various attentional switching in computer classroom.…

  4. Eye tracking and gating system for proton therapy of orbital tumors

    Energy Technology Data Exchange (ETDEWEB)

    Shin, Dongho; Yoo, Seung Hoon; Moon, Sung Ho; Yoon, Myonggeun; Lee, Se Byeong; Park, Sung Yong [Proton Therapy Center, National Cancer Center, Goyang, Gyeonggi 410-769 (Korea, Republic of); Department of Radiation Oncology, CHA Bundang Medical Center, CHA University, Seongnam, Gyeonggi 463-712 (Korea, Republic of); Proton Therapy Center, National Cancer Center, Goyang, Gyeonggi 410-769 (Korea, Republic of); Department of Radiological Science, Korea University, Seoul 136-703 (Korea, Republic of); Proton Therapy Center, National Cancer Center, Goyang, Gyeonggi 410-769 (Korea, Republic of); Proton Therapy Center, McLaren Cancer Institute, Flint, Michigan 48532 (United States)

    2012-07-15

    Purpose: A new motion-based gated proton therapy for the treatment of orbital tumors using real-time eye-tracking system was designed and evaluated. Methods: We developed our system by image-pattern matching, using a normalized cross-correlation technique with LabVIEW 8.6 and Vision Assistant 8.6 (National Instruments, Austin, TX). To measure the pixel spacing of an image consistently, four different calibration modes such as the point-detection, the edge-detection, the line-measurement, and the manual measurement mode were suggested and used. After these methods were applied to proton therapy, gating was performed, and radiation dose distributions were evaluated. Results: Moving phantom verification measurements resulted in errors of less than 0.1 mm for given ranges of translation. Dosimetric evaluation of the beam-gating system versus nongated treatment delivery with a moving phantom shows that while there was only 0.83 mm growth in lateral penumbra for gated radiotherapy, there was 4.95 mm growth in lateral penumbra in case of nongated exposure. The analysis from clinical results suggests that the average of eye movements depends distinctively on each patient by showing 0.44 mm, 0.45 mm, and 0.86 mm for three patients, respectively. Conclusions: The developed automatic eye-tracking based beam-gating system enabled us to perform high-precision proton radiotherapy of orbital tumors.

  5. Key issues of multiple access technique for LEO satellite communication systems

    Institute of Scientific and Technical Information of China (English)

    温萍萍; 顾学迈

    2004-01-01

    The large carrier frequency shift caused by the high-speed movement of satellite (Doppler effects) and the propagation delay on the up-down link are very critical issues in an LEO satellite communication system, which affects both the selection and the implementation of a suitable access method. A Doppler based multiple access technique is used here to control the flow and an MPRMA-HS protocol is proposed for the application in LEO satellite communication systems. The extended simulation trials prove that the proposed scheme seems to be a very promising access method.

  6. Numerical exploration of resonant dynamics in the system of Saturnian major satellites

    Science.gov (United States)

    Callegari, N.; Yokoyama, T.

    2010-12-01

    We numerically investigate the long-term dynamics of the Saturnian system by analyzing the Fourier spectra of ensembles of orbits taken around the current orbits of Mimas, Enceladus, Tethys, Rhea and Hyperion. We construct dynamical maps around the current position of these satellites in their respective phase spaces. The maps are the result of a great deal of numerical simulations where we adopt dense sets of initial conditions and different satellite configurations. Several structures associated to the current two-body mean-motion resonances, unstable regions associated to close approaches between the satellites, and three-body mean-motion resonances in the system, are identified in the map.

  7. A bio-inspired apposition compound eye machine vision sensor system.

    Science.gov (United States)

    Davis, J D; Barrett, S F; Wright, C H G; Wilcox, M

    2009-12-01

    The Wyoming Information, Signal Processing, and Robotics Laboratory is developing a wide variety of bio-inspired vision sensors. We are interested in exploring the vision system of various insects and adapting some of their features toward the development of specialized vision sensors. We do not attempt to supplant traditional digital imaging techniques but rather develop sensor systems tailor made for the application at hand. We envision that many applications may require a hybrid approach using conventional digital imaging techniques enhanced with bio-inspired analogue sensors. In this specific project, we investigated the apposition compound eye and its characteristics commonly found in diurnal insects and certain species of arthropods. We developed and characterized an array of apposition compound eye-type sensors and tested them on an autonomous robotic vehicle. The robot exhibits the ability to follow a pre-defined target and avoid specified obstacles using a simple control algorithm.

  8. Eye-hand Hybrid Gesture Recognition System for Human Machine Interface

    Directory of Open Access Journals (Sweden)

    N. R. Raajan

    2013-04-01

    Full Text Available Gesture Recognition has become a way for computers to recognise and understand human body language. They bridge the gap between machines and human beings and make the primitive interfaces like keyboards and mice redundant. This paper suggests a hybrid gesture recognition system for computer interface and wireless robot control. The real-time eye-hand gesture recognition system can be used for computer drawing, navigating cursors and simulating mouse clicks, playing games, controlling a wireless robot with commands and more. The robot illustrated in this paper is controlled by RF module. Playing a PING-PONG game has also been demonstrated using the gestures. The Haar cascade classifiers and template matching are used to detect eye gestures and convex hull for finding the defects and counting the number of fingers in the given region.

  9. A bio-inspired apposition compound eye machine vision sensor system

    Energy Technology Data Exchange (ETDEWEB)

    Davis, J D [Applied Research Laboratories, University of Texas, 10000 Burnet Rd, Austin, TX 78757 (United States); Barrett, S F; Wright, C H G [Electrical and Computer Engineering, University of Wyoming, Dept 3295 1000 E. University Ave, Laramie, WY 82071 (United States); Wilcox, M, E-mail: steveb@uwyo.ed [Department of Biology, United States Air Force Academy, CO 80840 (United States)

    2009-12-15

    The Wyoming Information, Signal Processing, and Robotics Laboratory is developing a wide variety of bio-inspired vision sensors. We are interested in exploring the vision system of various insects and adapting some of their features toward the development of specialized vision sensors. We do not attempt to supplant traditional digital imaging techniques but rather develop sensor systems tailor made for the application at hand. We envision that many applications may require a hybrid approach using conventional digital imaging techniques enhanced with bio-inspired analogue sensors. In this specific project, we investigated the apposition compound eye and its characteristics commonly found in diurnal insects and certain species of arthropods. We developed and characterized an array of apposition compound eye-type sensors and tested them on an autonomous robotic vehicle. The robot exhibits the ability to follow a pre-defined target and avoid specified obstacles using a simple control algorithm.

  10. Technical and programmatic constraints in dynamic verification of satellite mechanical systems

    Science.gov (United States)

    Stavrinidis, C.; Klein, M.; Brunner, O.; Newerla, A.

    1996-01-01

    The development and verification of satellite systems covers various programmatic options. In the mechanical systems area, spacecraft test verification options include static, shaker vibration, modal survey, thermoelastic, acoustic, impact and other environmental tests. Development and verification tests influence the provision of satellite hardware, e.g. the structural model, engineering model, flight model, postflight etc., which need to be adopted by projects. In particular, adequate understanding of the satellite dynamic characteristics is essential for flight acceptance by launcher authorities. In general, a satellite shaker vibration test is requested by launcher authorities for expendable launchers. For the latter the launcher/satellite interface is well defined at the launcher clampband/separation device, and the interface is considered conveniently as a single point at the centre of the clampband. Recently the need has been identified to refine the interface idealization in launcher/satellite coupled loads dynamic analysis, particularly in cases where concentrated satellite loads are introduced at the interface, e.g. platform support struts. In the case of shuttle payloads, which are attached directly to the shuttle, shaker vibration at a single interface is not meaningful. Shuttle launcher authorities require identification of the satellite dynamic characteristics, e.g. by modal survey, and structural verification can be demonstrated by analysis, testing or a combination of analysis and testing. In the case of large satellite systems, which cannot be tested due to the limitation of the vibration shaker test facilities, a similar approach can be adapted for expendable launchers. In such an approach the dynamic characteristics of the satellite system will be identified by the modal survey test, and detailed satellite verification/qualification will be accomplished by analysis supported by subsystem and component level tests. Mechanical strength verification

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

    Science.gov (United States)

    Snowball, A. E.

    1986-06-01

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

  12. An Image-Based Sensor System for Autonomous Rendez-Vous with Uncooperative Satellites

    CERN Document Server

    Miravet, Carlos; Krouch, Eloise; del Cura, Juan Manuel

    2008-01-01

    In this paper are described the image processing algorithms developed by SENER, Ingenieria y Sistemas to cope with the problem of image-based, autonomous rendez-vous (RV) with an orbiting satellite. The methods developed have a direct application in the OLEV (Orbital Life Extension Extension Vehicle) mission. OLEV is a commercial mission under development by a consortium formed by Swedish Space Corporation, Kayser-Threde and SENER, aimed to extend the operational life of geostationary telecommunication satellites by supplying them control, navigation and guidance services. OLEV is planned to use a set of cameras to determine the angular position and distance to the client satellite during the complete phases of rendez-vous and docking, thus enabling the operation with satellites not equipped with any specific navigational aid to provide support during the approach. The ability to operate with un-equipped client satellites significantly expands the range of applicability of the system under development, compar...

  13. A novel spelling system for locked-in syndrome patients using only eye contact.

    Science.gov (United States)

    Kopsky, David Jos; Winninghoff, Yvonne; Winninghoff, Albert C M; Stolwijk-Swüste, Janneke Marjan

    2014-01-01

    We developed and evaluated a novel spelling system for patients with locked-in syndrome: patients with tetraplegia, not able to talk, and only able to blink their eyes. A new communication grid was compared with existing non-technical communication methods for practical daily use. The means of the number of decision steps to reach a full sentence were compared testing 10 sentences relevant in daily care. These 10 sentences together encompass all letters of the alphabet. The new communication grid is organised alphabetically in 4 columns and 2 main rows, with each row subdivided in three rows. The first column contains vowels while the other columns contain consonants. Letters in each column are alphabetically ordered. When spelling a sentence the conversation partner counts the columns, until the patient indicates by an upward eye movement that the column contains the intended letter. Hereafter, the patient indicates by looking straight ahead or by looking down, whether the intended letter is in the upper or in the lower main row, respectively. The conversation partner will then read out the letters until the patient indicates the intended letter. Compared to other spelling systems, this system requires only vertical eye movement, is easier to memorise, and faster in use. The comparison of means of decision steps to reach the 10 full sentences for different communication grids shows that using the new communication grid is approximately one-third to three times faster than the existing spelling systems (p = 0.005). This new grid is a valuable communication tool, especially in situations, such as bathing, getting dressed or out of house activities where no devices are available. Implications for Rehabilitation Communication with patients with locked-in syndrome is a complicated and strenuous task. Communication methods, such as the alphabet board and brain-computer interfaces, are time consuming or too sophisticated to use in daily life tasks. This communication

  14. The state of the atmosphere as inferred from the FGGE satellite observing systems during SOP-1

    Science.gov (United States)

    Halem, M.; Kalnay, E.; Baker, W. E.; Atlas, R.

    1981-01-01

    Data assimilation experiments were performed to test the influence of different elements of the satellite observing systems. Results from some of the experiments are presented. These findings show that the FGGE satellite systems are able to infer the three-dimensional motion field and improve the representation of the large-scale state of the atmosphere. Preliminary results of the forecast impact of the FGGE data sets are also presented.

  15. Propagation Models for Dimensioning and Estimation of Performance and Availability of New Satellite Communication Systems

    OpenAIRE

    2001-01-01

    A rapid growth of new satellite systems utilizing the Ka-band (27 – 40 Ghz) and even higher frequencies is expected in the coming years. The services offered will include broadband communication, interactive broadcasting, multimedia applications, interconnection of local area networks and Internet connectivity. Many of the new systems will use technologies as multiple spot-beams, onboard processing, and switching of packets between beams and inter satellite links. Because of congestion in the...

  16. A Novel System for Moving Object Detection Using Bionic Compound Eyes

    Institute of Scientific and Technical Information of China (English)

    Huabo Sun; Haimeng Zhao; Peter Mooney; Hongying Zhao; Daping Liu; Lei Yan

    2011-01-01

    Conventional moving target detection focuses on algorithms to improve detection efficiency. These algorithms pay less attention to the image acquisition means, and usually solve specific problems. This often results in poor flexibility and reusability. Insect compound eyes offer unique advantages for moving target detection and these advantages have attracted the attention of many researchers in recent years. In this paper we proposed a new system for moving target detection. We used the detection mechanism of insect compound eyes for the simulation of the characteristics of structure, control, and function. We discussed the design scheme of the system, the development of the bionic control circuit, and introduced the proposed mathematical model of bionic compound eyes for data acquisition and object detection. After this the integrated system was described and discussed. Our paper presents a novel approach for moving target detection. This approach effectively tackles some of the well-known problems in the field of view, resolution, and real-time processing problems in moving target detection.

  17. Design and verifications of an eye model fitted with contact lenses for wavefront measurement systems

    Science.gov (United States)

    Cheng, Yuan-Chieh; Chen, Jia-Hong; Chang, Rong-Jie; Wang, Chung-Yen; Hsu, Wei-Yao; Wang, Pei-Jen

    2015-09-01

    Contact lenses are typically measured by the wet-box method because of the high optical power resulting from the anterior central curvature of cornea, even though the back vertex power of the lenses are small. In this study, an optical measurement system based on the Shack-Hartmann wavefront principle was established to investigate the aberrations of soft contact lenses. Fitting conditions were micmicked to study the optical design of an eye model with various topographical shapes in the anterior cornea. Initially, the contact lenses were measured by the wet-box method, and then by fitting the various topographical shapes of cornea to the eye model. In addition, an optics simulation program was employed to determine the sources of errors and assess the accuracy of the system. Finally, samples of soft contact lenses with various Diopters were measured; and, both simulations and experimental results were compared for resolving the controversies of fitting contact lenses to an eye model for optical measurements. More importantly, the results show that the proposed system can be employed for study of primary aberrations in contact lenses.

  18. Propagation effects handbook for satellite systems design. A summary of propagation impairments on 10 to 100 GHz satellite links with techniques for system design

    Science.gov (United States)

    Ippolito, Louis J.

    1989-01-01

    The NASA Propagation Effects Handbook for Satellite Systems Design provides a systematic compilation of the major propagation effects experienced on space-Earth paths in the 10 to 100 GHz frequency band region. It provides both a detailed description of the propagation phenomenon and a summary of the impact of the effect on the communications system design and performance. Chapter 2 through 5 describe the propagation effects, prediction models, and available experimental data bases. In Chapter 6, design techniques and prediction methods available for evaluating propagation effects on space-Earth communication systems are presented. Chapter 7 addresses the system design process and how the effects of propagation on system design and performance should be considered and how that can be mitigated. Examples of operational and planned Ku, Ka, and EHF satellite communications systems are given.

  19. A Synthetic Aperture System Based on Backscattering Signals of Compass Navigation Satellite: Concept and Feasibility

    Directory of Open Access Journals (Sweden)

    Wang Hai-yang

    2012-06-01

    Full Text Available A concept of a bi-static geosynchronous synthetic aperture system, which is formed by reusing backscattered signals of Compass Navigation Satellite System (CNSS, is proposed. The geometric relations of a geostationary satellite of CNSS, located on a geosynchronous satellite receiver, which is illuminated by the backscattered energy of a satellite of CNSS, and a ground station is built up, and following the relations as well as principle of synthetic aperture radar, we expatiate the feasibility of the system by considering parameters such as imaging resolution, ratio of signal to noise and link budget, etc.. Besides, the potential remote sensing applications for measurement of terrain humidity, characteristics of space-time dynamics of changing of terrain surface and atmospheric characteristic, etc..

  20. Design description report for a photovoltaic power system for a remote satellite earth terminal

    Science.gov (United States)

    Marshall, N. A.; Naff, G. J.

    1987-01-01

    A photovoltaic (PV) power system has been installed as an adjunct to an agricultural school at Wawatobi on the large northern island of the Republic of Indonesia. Its purpose is to provide power for a satellite earth station and a classroom. The renewable energy developed supports the video and audio teleconferencing systems as well as the facility at large. The ground station may later be used to provide telephone service. The installation was made in support of the Agency for International Development's Rural Satellite Program, whose purpose is to demonstrate the use of satellite communications for rural development assistance applications. The objective of this particular PV power system is to demonstrate the suitability of a hybrid PV engine-generator configuration for remote satellite earth stations.

  1. A MATLAB-based eye tracking control system using non-invasive helmet head restraint in the macaque.

    Science.gov (United States)

    De Luna, Paolo; Mohamed Mustafar, Mohamed Faiz Bin; Rainer, Gregor

    2014-09-30

    Tracking eye position is vital for behavioral and neurophysiological investigations in systems and cognitive neuroscience. Infrared camera systems which are now available can be used for eye tracking without the need to surgically implant magnetic search coils. These systems are generally employed using rigid head fixation in monkeys, which maintains the eye in a constant position and facilitates eye tracking. We investigate the use of non-rigid head fixation using a helmet that constrains only general head orientation and allows some freedom of movement. We present a MATLAB software solution to gather and process eye position data, present visual stimuli, interact with various devices, provide experimenter feedback and store data for offline analysis. Our software solution achieves excellent timing performance due to the use of data streaming, instead of the traditionally employed data storage mode for processing analog eye position data. We present behavioral data from two monkeys, demonstrating that adequate performance levels can be achieved on a simple fixation paradigm and show how performance depends on parameters such as fixation window size. Our findings suggest that non-rigid head restraint can be employed for behavioral training and testing on a variety of gaze-dependent visual paradigms, reducing the need for rigid head restraint systems for some applications. While developed for macaque monkey, our system of course can work equally well for applications in human eye tracking where head constraint is undesirable. Copyright © 2014. Published by Elsevier B.V.

  2. Communication Systems through Artificial Earth Satellites (Selected Pages)

    Science.gov (United States)

    1987-02-05

    POX Fs (8.2.11) is 0(F) dF If on input of weighing circuit fluctuation noise with uniform spectrum acts, spectral power density in numerator and...Possibly also realization MV with asynchronous operation of terrestrial stations, that we will designate through MVA . In the case MVA each terrestrial...according to the frequcrncy. With MVA through receiving-transmitting equipment of satellite into some tiMe intervals simultaneous possible passage of signals

  3. 视线跟踪系统中眼睛睁闭检测算法研究%Eye state detection algorithm of eye tracking system

    Institute of Scientific and Technical Information of China (English)

    邓宏平; 李斌; 姚鹏; 吴伟; 王建宇; 庄镇泉

    2012-01-01

    眼睛睁闭检测在视线跟踪系统中具有重要意义.为提高检测的准确性,提出了一种基于Harris算子的检测方法.该方法首先利用Harris算子计算图像的角点量,然后搜索图像中角点量最大的位置,以该位置为中心,设置一个区域,统计该区域内角点量总和占整幅图像角点量总和的比例,通过将该比例与阈值相比较来确定眼睛的状态.实验结果表明,本算法具有较高的鲁棒性和准确率,并能满足实时性要求.%Eye state detection is important in eye tracking system. In order to improve the correctness, a Harris operator based new algorithm is proposed. First, Harris operator is used to calculate the cornerness of eye image. Then, the position of maximum cornerness is set as center of a region. The proportion of total cornerness in the region and all images are used to detect eye state. Experimental results definitely verify the robustness and accuracy of the new algorithm. Especially, this new algorithm is suitable for real-time applications.

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

    Science.gov (United States)

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

    1993-01-01

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

  5. Automated tracking and grasping of a moving object with a robotic hand-eye system

    Energy Technology Data Exchange (ETDEWEB)

    Allen, P.K.; Timcenko, A.; Yoshimi, B.; Michelman, P. (Columbia Univ., NY (United States). Dept. of Computer Science)

    1993-04-01

    Most robotic grasping tasks assume a stationary or fixed object. In this paper, the authors explore the requirements for tracking and grasping a moving object. The focus of the work is to achieve a high level of interaction between a real-time vision system capable of tracking moving objects in 3-D and a robot arm with gripper that can be used to pick up a moving object. There is an interest in exploring the interplay of hand--eye coordination for dynamic grasping takes such as grasping of parts on a moving conveyor system, assembly of articulated parts, or for grasping from a mobile robotic system. Coordination between an organisms sensing modalities and motor control system is a hallmark of intelligent behavior, and they are pursuing the goal of building an integrated sensing and actuation system that can operate in dynamic as opposed to static environments. The system they have built addresses three distinct problems in robotic hand--eye coordination for grasping moving objects: fast computation of 3-D motion parameters from vision, predictive control of a moving robotic arm to track a moving object, and interception and grasping. The system is able to operate at approximately human arm movement rates, and experimental results in which a moving model train is tracked is presented, stably grasped, and picked up by the system. The algorithms they have developed that relate sensing to actuation are quite general and applicable to a variety of complex robotic tasks that require visual feedback for arm and hand control.

  6. New Generation of Broadcasting Satellite Systems: New Markets and Business Developments

    Science.gov (United States)

    Perrot, Bruno; Michel, Cyril; Villaret, Stéfanie

    2002-01-01

    Since the deployment of the first Digital Broadcasting Satellite Systems, European satellite operators and service providers have been faced with the continuously increasing demand for Digital Broadcasting Services. Their success is built on the availability of the MPEG and DVB standards. Undoubtedly, conventional digital television broadcasting is today the `Killer' application. Various service providers already offer multimedia applications through DVB-S systems based upon the `Push' technology. Although these services do not currently represent the core business for broadcasting satellite operators, their percentage is increasing. `Push' technology services include Data Carousel, Webcasting, Turbo Internet, File casting and so on. Such technology can support the implementation of different emerging multimedia services scenarios from Newsgroups, Network collaborative learning, and tele-medicine, to others that may be invented in the near future. The penetration rate of multi-channel television reception is still increasing. Broadcasting satellites benefit both from the development of new, more segmented and sophisticated offers and from the development of Internet services. Satellite is likely to enter these new markets at different levels of the value chain: Even if the satellite has demonstrated its capacity to fully serve the television, combinations with other networks may be necessary to address the new markets: at the consumer premises, Internet-related services will require a return path; at the backbone level, satellite becomes a component of a full telecommunications solution. This article focuses on the European market and proposes:

  7. The EMC of satellite power systems and DoD C-E systems

    Science.gov (United States)

    Atkinson, J. H.; Aasen, M. D.

    1980-01-01

    The solar power satellite (SPS) technical parameters that are needed to accurately assess the electromagnetic compatibility (EMC) between SPS systems and DoD communications-electronics (C-E) systems are identified and assessed. The type of electromagnetic interactions that could degrade the performance of C-E systems are described and the major military installations in the southwestern portions of CONUS where specially sensitive C-E systems are being used for combat training and evaluation are identified. Classes of C-E systems that are generally in the vicinity of these military installations are considered. The Technical parameters that govern the degree of compatibility of the SPS with these C-E systems, and some technical requirements that are necessary to ensure short-term and long-term EMC are identified.

  8. Eye motion triggered self-powered mechnosensational communication system using triboelectric nanogenerator.

    Science.gov (United States)

    Pu, Xianjie; Guo, Hengyu; Chen, Jie; Wang, Xue; Xi, Yi; Hu, Chenguo; Wang, Zhong Lin

    2017-07-01

    Mechnosensational human-machine interfaces (HMIs) can greatly extend communication channels between human and external devices in a natural way. The mechnosensational HMIs based on biopotential signals have been developing slowly owing to the low signal-to-noise ratio and poor stability. In eye motions, the corneal-retinal potential caused by hyperpolarization and depolarization is very weak. However, the mechanical micromotion of the skin around the corners of eyes has never been considered as a good trigger signal source. We report a novel triboelectric nanogenerator (TENG)-based micromotion sensor enabled by the coupling of triboelectricity and electrostatic induction. By using an indium tin oxide electrode and two opposite tribomaterials, the proposed flexible and transparent sensor is capable of effectively capturing eye blink motion with a super-high signal level (~750 mV) compared with the traditional electrooculogram approach (~1 mV). The sensor is fixed on a pair of glasses and applied in two real-time mechnosensational HMIs-the smart home control system and the wireless hands-free typing system with advantages of super-high sensitivity, stability, easy operation, and low cost. This TENG-based micromotion sensor is distinct and unique in its fundamental mechanism, which provides a novel design concept for intelligent sensor technique and shows great potential application in mechnosensational HMIs.

  9. Learning robotic eye-arm-hand coordination from human demonstration: a coupled dynamical systems approach.

    Science.gov (United States)

    Lukic, Luka; Santos-Victor, José; Billard, Aude

    2014-04-01

    We investigate the role of obstacle avoidance in visually guided reaching and grasping movements. We report on a human study in which subjects performed prehensile motion with obstacle avoidance where the position of the obstacle was systematically varied across trials. These experiments suggest that reaching with obstacle avoidance is organized in a sequential manner, where the obstacle acts as an intermediary target. Furthermore, we demonstrate that the notion of workspace travelled by the hand is embedded explicitly in a forward planning scheme, which is actively involved in detecting obstacles on the way when performing reaching. We find that the gaze proactively coordinates the pattern of eye-arm motion during obstacle avoidance. This study provides also a quantitative assessment of the coupling between the eye-arm-hand motion. We show that the coupling follows regular phase dependencies and is unaltered during obstacle avoidance. These observations provide a basis for the design of a computational model. Our controller extends the coupled dynamical systems framework and provides fast and synchronous control of the eyes, the arm and the hand within a single and compact framework, mimicking similar control system found in humans. We validate our model for visuomotor control of a humanoid robot.

  10. A psychotechnological review on eye-tracking systems: towards user experience.

    Science.gov (United States)

    Mele, Maria Laura; Federici, Stefano

    2012-07-01

    The aim of the present work is to show a critical review of the international literature on eye-tracking technologies by focusing on those features that characterize them as 'psychotechnologies'. A critical literature review was conducted through the main psychology, engineering, and computer sciences databases by following specific inclusion and exclusion criteria. A total of 46 matches from 1998 to 2010 were selected for content analysis. Results have been divided into four broad thematic areas. We found that, although there is a growing attention to end-users, most of the studies reviewed in this work are far from being considered as adopting holistic human-computer interaction models that include both individual differences and needs of users. User is often considered only as a measurement object of the functioning of the technological system and not as a real alter-ego of the intrasystemic interaction. In order to fully benefit from the communicative functions of gaze, the research on eye-tracking must emphasize user experience. Eye-tracking systems would become an effective assistive technology for integration, adaptation and neutralization of the environmental barrier only when a holistic model can be applied for both design processes and assessment of the functional components of the interaction.

  11. The Fly's Eye Camera System -- an instrument design for large \\'etendue time-domain survey

    CERN Document Server

    Pál, András; Csépány, Gergely; Jaskó, Attila; Schlaffer, Ferenc; Vida, Krisztián; Mező, György; Döbrentei, László; Farkas, Ernő; Kiss, Csaba; Oláh, Katalin; Regály, Zsolt

    2013-01-01

    In this paper we briefly summarize the design concepts of the Fly's Eye Camera System, a proposed high resolution all-sky monitoring device which intends to perform high cadence time domain astronomy in multiple optical passbands while still accomplish a high \\'etendue. Fundings have already been accepted by the Hungarian Academy of Sciences in order to design and build a Fly's Eye device unit. Beyond the technical details and the actual scientific goals, this paper also discusses the possibilities and yields of a network operation involving ~10 sites distributed geographically in a nearly homogeneous manner. Currently, we expect to finalize the mount assembly -- that performs the sidereal tracking during the exposures -- until the end of 2012 and to have a working prototype with a reduced number of individual cameras sometimes in the spring or summer of 2013.

  12. The Fly's Eye Camera System -- an instrument design for large \\'etendue time-domain survey

    CERN Document Server

    Csépány, Gergely; Vida, Krisztián; Regály, Zsolt; Mészáros, László; Oláh, Katalin; Kiss, Csaba; Döbrentei, László; Jaskó, Attila; Mező, György; Farkas, Ernő

    2014-01-01

    In this paper we briefly summarize the design concepts of the Fly's Eye Camera System, a proposed high resolution all-sky monitoring device which intends to perform high cadence time domain astronomy in multiple optical passbands while still accomplish a high \\'etendue. Fundings have already been accepted by the Hungarian Academy of Sciences in order to design and build a Fly's Eye device unit. Beyond the technical details and the actual scientific goals, this paper also discusses the possibilities and yields of a network operation involving $\\sim10$ sites distributed geographically in a nearly homogeneous manner. Currently, we expect to finalize the mount assembly -- that performs the sidereal tracking during the exposures -- until the end of 2012 and to have a working prototype with a reduced number of individual cameras sometimes in the spring or summer of 2013.

  13. Edge detection of iris of the eye for human biometric identification system

    Directory of Open Access Journals (Sweden)

    Kateryna O. Tryfonova

    2015-03-01

    Full Text Available Method of human biometric identification by iris of the eye is considered as one of the most accurate and reliable methods of identification. Aim of the research is to solve the problem of edge detection of digital image of the human eye iris to be able to implement human biometric identification system by means of mobile device. To achieve this aim the algorithm of edge detection by Canny is considered in work. It consists of the following steps: smoothing, finding gradients, non-maximum suppression, double thresholding with hysteresis. The software implementation of the Canny algorithm is carried out for the Android mobile platform with the use of high level programming language Java.

  14. Arthropod eyes: The early Cambrian fossil record and divergent evolution of visual systems.

    Science.gov (United States)

    Strausfeld, Nicholas J; Ma, Xiaoya; Edgecombe, Gregory D; Fortey, Richard A; Land, Michael F; Liu, Yu; Cong, Peiyun; Hou, Xianguang

    2016-03-01

    Four types of eyes serve the visual neuropils of extant arthropods: compound retinas composed of adjacent facets; a visual surface populated by spaced eyelets; a smooth transparent cuticle providing inwardly directed lens cylinders; and single-lens eyes. The first type is a characteristic of pancrustaceans, the eyes of which comprise lenses arranged as hexagonal or rectilinear arrays, each lens crowning 8-9 photoreceptor neurons. Except for Scutigeromorpha, the second type typifies Myriapoda whose relatively large eyelets surmount numerous photoreceptive rhabdoms stacked together as tiers. Scutigeromorph eyes are facetted, each lens crowning some dozen photoreceptor neurons of a modified apposition-type eye. Extant chelicerate eyes are single-lensed except in xiphosurans, whose lateral eyes comprise a cuticle with a smooth outer surface and an inner one providing regular arrays of lens cylinders. This account discusses whether these disparate eye types speak for or against divergence from one ancestral eye type. Previous considerations of eye evolution, focusing on the eyes of trilobites and on facet proliferation in xiphosurans and myriapods, have proposed that the mode of development of eyes in those taxa is distinct from that of pancrustaceans and is the plesiomorphic condition from which facetted eyes have evolved. But the recent discovery of enormous regularly facetted compound eyes belonging to early Cambrian radiodontans suggests that high-resolution facetted eyes with superior optics may be the ground pattern organization for arthropods, predating the evolution of arthrodization and jointed post-protocerebral appendages. Here we provide evidence that compound eye organization in stem-group euarthropods of the Cambrian can be understood in terms of eye morphologies diverging from this ancestral radiodontan-type ground pattern. We show that in certain Cambrian groups apposition eyes relate to fixed or mobile eyestalks, whereas other groups reveal concomitant

  15. System Design of a S-band Solid-state Transmitter in Satellite-borne SAR

    Directory of Open Access Journals (Sweden)

    Zhao Hai-yang

    2014-06-01

    Full Text Available The system design of a S-band solid-state transmitter in satellite-borne SAR is introduced. A series of critical technologies, such as high reliability, environmental adaptability, and structure miniaturization, which are necessary in satellite applications, are analyzed and discussed. The technologies are experimentally verified at different periods. Multichannel combined technology is used for the transmitter, and the output peak power is more than 3 kW. Because of the high efficiency, small size, lightweight, and high power, it is especially applicable in small satellite platforms.

  16. Application of communications satellites to educational development. [technology utilization/information systems - bibliographies

    Science.gov (United States)

    Morgan, R. P.

    1975-01-01

    A summary of research is presented. The broad objectives of this interdisciplinary research effort were: (1) to assess the role of satellite communications as a means of improving education in the United States, as well as in less-developed areas of the world; (2) to generate basic knowledge which will aid in making rational decisions about satellite application in the field of education in the years ahead; (3) to devise systems and strategies for improving education; and (4) to educate individuals who will be knowledgeable about aspects of satellite communications policy which transcend any single discipline.

  17. System Design and In-orbit Verification of the HJ-1-C SAR Satellite

    Directory of Open Access Journals (Sweden)

    Zhang Run-ning

    2014-06-01

    Full Text Available HJ-1-C is a SAR satellite owned by the Chinese Environment and Natural Disaster Monitoring constellation, and works together with the optical satellites HJ-1-A/B for monitoring environment and natural disasters. In this paper, the system design and characteristics of the first Chinese civil SAR satellite are described. In addition, the interface relation between SAR payload and platform is studied. Meanwhile, the data transmission capability, attitude, power, and temperature control that support SAR imaging are reviewed. Finally, the corresponding in-orbit verification results are presented.

  18. Earth's thermal radiation sensors for attitude determination systems of small satellites

    Science.gov (United States)

    Vertat, I.; Linhart, R.; Masopust, J.; Vobornik, A.; Dudacek, L.

    2017-07-01

    Satellite attitude determination is a complex process with expensive hardware and software and it could consume the most of resources (volume, mass, electric power), especially of small satellites as CubeSats. Thermal radiation infrared detectors could be one of useful sensors for attitude determination systems in such small satellites. Nowadays, these sensors are widely used in contact-less thermometers and thermo-cameras resulting in a low-cost technology. On low Earth orbits the infrared thermal sensors can be utilized for coarse attitude determination against a relative warm and close Earth's globe.

  19. Clouds and the Earth's Radiant Energy System (CERES) Visualization Single Satellite Footprint (SSF) Plot Generator

    Science.gov (United States)

    Barsi, Julia A.

    1995-01-01

    The first Clouds and the Earth's Radiant Energy System (CERES) instrument will be launched in 1997 to collect data on the Earth's radiation budget. The data retrieved from the satellite will be processed through twelve subsystems. The Single Satellite Footprint (SSF) plot generator software was written to assist scientists in the early stages of CERES data analysis, producing two-dimensional plots of the footprint radiation and cloud data generated by one of the subsystems. Until the satellite is launched, however, software developers need verification tools to check their code. This plot generator will aid programmers by geolocating algorithm result on a global map.

  20. Changes in anterior chamber eye during accommodation as assessed using a Dual Scheimpflug system

    Directory of Open Access Journals (Sweden)

    Alberto Domínguez-Vicent

    2014-08-01

    Full Text Available Purpose: To study the changes in anterior chamber depth (ACD, anterior chamber angle (ACA, and pupil diameter (PD during accommodation. Methods: Eighty eyes of 80 subjects, aged 22 to 40 years, were included. The rotating Dual Scheimpflug and a Placido disc system (Galilei G4, Ziemer Ophthalmic Systems AG, Switzerland was used to measure the changes in ACD, ACA, and PD during accommodation. ACD measurement was taken for the central zone and for 4 more positions, each in different orientation (nasal, superior, temporal and inferior, 4 mm away from the centre. ACA was measured for the whole eye as well for the nasal, superior, temporal, and inferior quadrants. These metrics were obtained for various accommodation stimuli, ranging from +1 D to -4 D in 1-D steps. Results: For a given position, the ACD did not vary significantly with accommodation. For the central ACD, the percentage of relative change between far and near vision was -4.11%. The ACA was significantly lower at the inferior, temporal, and superior positions. There was no change in the ACA of the whole eye and that of the nasal orientation. These two eye metrics were significantly lower in the superior-nasal than in the inferior-temporal region. At each vergence studied, the PD decreased significantly with accommodation. The relative change after the -4 D stimulus was -8.13%. Conclusion: ACA and PD varied significantly with accommodation, whereas no such variation of ACD was observed. Further, the anterior chamber was found to be asymmetrical, with the nasal-superior area becoming significantly shallower than the inferior temporal region.

  1. Changes in anterior chamber eye during accommodation as assessed using a Dual Scheimpflug system.

    Science.gov (United States)

    Domínguez-Vicent, Alberto; Monsálvez-Romín, Daniel; Albarrán-Diego, César; Sanchis-Jurado, Vicent; Montés-Micó, Robert

    2014-08-01

    To study the changes in anterior chamber depth (ACD), anterior chamber angle (ACA), and pupil diameter (PD) during accommodation. Eighty eyes of 80 subjects, aged 22 to 40 years, were included. The rotating Dual Scheimpflug and a Placido disc system (Galilei G4, Ziemer Ophthalmic Systems AG, Switzerland) was used to measure the changes in ACD, ACA, and PD during accommodation. ACD measurement was taken for the central zone and for 4 more positions, each in different orientation (nasal, superior, temporal and inferior), 4 mm away from the centre. ACA was measured for the whole eye as well for the nasal, superior, temporal, and inferior quadrants. These metrics were obtained for various accommodation stimuli, ranging from +1 D to -4 D in 1-D steps. For a given position, the ACD did not vary significantly with accommodation. For the central ACD, the percentage of relative change between far and near vision was -4.11%. The ACA was significantly lower at the inferior, temporal, and superior positions. There was no change in the ACA of the whole eye and that of the nasal orientation. These two eye metrics were significantly lower in the superior-nasal than in the inferior-temporal region. At each vergence studied, the PD decreased significantly with accommodation. The relative change after the -4 D stimulus was -8.13%. ACA and PD varied significantly with accommodation, whereas no such variation of ACD was observed. Further, the anterior chamber was found to be asymmetrical, with the nasal-superior area becoming significantly shallower than the inferior temporal region.

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

    Science.gov (United States)

    Bowen, Robert R.

    1990-01-01

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

  3. Reusable Reentry Satellite (RRS) system design study: System cost estimates document

    Science.gov (United States)

    1991-01-01

    The Reusable Reentry Satellite (RRS) program was initiated to provide life science investigators relatively inexpensive, frequent access to space for extended periods of time with eventual satellite recovery on earth. The RRS will provide an on-orbit laboratory for research on biological and material processes, be launched from a number of expendable launch vehicles, and operate in Low-Altitude Earth Orbit (LEO) as a free-flying unmanned laboratory. SAIC's design will provide independent atmospheric reentry and soft landing in the continental U.S., orbit for a maximum of 60 days, and will sustain three flights per year for 10 years. The Reusable Reentry Vehicle (RRV) will be 3-axis stabilized with artificial gravity up to 1.5g's, be rugged and easily maintainable, and have a modular design to accommodate a satellite bus and separate modular payloads (e.g., rodent module, general biological module, ESA microgravity botany facility, general botany module). The purpose of this System Cost Estimate Document is to provide a Life Cycle Cost Estimate (LCCE) for a NASA RRS Program using SAIC's RRS design. The estimate includes development, procurement, and 10 years of operations and support (O&S) costs for NASA's RRS program. The estimate does not include costs for other agencies which may track or interface with the RRS program (e.g., Air Force tracking agencies or individual RRS experimenters involved with special payload modules (PM's)). The life cycle cost estimate extends over the 10 year operation and support period FY99-2008.

  4. Numerical modeling of a Global Navigation Satellite System in a general relativistic framework

    CERN Document Server

    Delva, P; Cadez, A

    2010-01-01

    In this article we model a Global Navigation Satellite System (GNSS) in a Schwarzschild space-time, as a first approximation of the relativistic geometry around the Earth. The closed time-like and scattering light-like geodesics are obtained analytically, describing respectively trajectories of satellites and electromagnetic signals. We implement an algorithm to calculate Schwarzschild coordinates of a GNSS user who receives proper times sent by four satellites, knowing their orbital parameters; the inverse procedure is implemented to check for consistency. The constellation of satellites therefore realizes a geocentric inertial reference system with no \\emph{a priori} realization of a terrestrial reference frame. We show that the calculation is very fast and could be implemented in a real GNSS, as an alternative to usual post-Newtonian corrections. Effects of non-gravitational perturbations on positioning errors are assessed, and methods to reduce them are sketched. In particular, inter-links between satelli...

  5. Cochannel and Adjacent-Channel Interference in Nonlinear Minimum-Shift-Keyed Satellite System

    Science.gov (United States)

    Yu, John

    1995-01-01

    The interference susceptibility of a serial-minimum-shift-keyed (SMSK) modulation system to an interfering signal transmitted through a satellite link with cascaded nonlinear elements was investigated through computer simulation. The satellite link evaluated in this study represented NASA's Advanced Communications Technology Satellite (ACTS) system. Specifically, nonlinear characteristics were used that had specified amplitude-modulation to amplitude-modulation and amplitude-modulation to phase-modulation transfer characteristics obtained from the actual ACTS hardware. Two measurement scenarios were analyzed: degradation of an MSK satellite link from cochannel interference and from adjacent-channel interference. Interference was evaluated in terms of the probability of bit error rate (BER) versus energy per bit over noise power density Eb/No.

  6. A new approach to design of quasi-isotropic antenna systems for satellite applications

    DEFF Research Database (Denmark)

    Schjær-Jacobsen, Hans; Hansen, J.E.

    1976-01-01

    The new approach considered takes into account the maximum error of the quasi-isotropic radiation pattern relative to the ideal pattern. A design example involving a spherical satellite with quarter wave monopoles is used to demonstrate the effectiveness of the new approach. An investigation...... is conducted concerning the minimax optimization of power radiation patterns. It is shown that the minimax objective represents a useful alternative to the isotropy concept in the design of quasi-isotropic antenna systems for satellite applications....

  7. A new approach to design of quasi-isotropic antenna systems for satellite applications

    DEFF Research Database (Denmark)

    Schjær-Jacobsen, Hans; Hansen, J.E.

    1976-01-01

    The new approach considered takes into account the maximum error of the quasi-isotropic radiation pattern relative to the ideal pattern. A design example involving a spherical satellite with quarter wave monopoles is used to demonstrate the effectiveness of the new approach. An investigation...... is conducted concerning the minimax optimization of power radiation patterns. It is shown that the minimax objective represents a useful alternative to the isotropy concept in the design of quasi-isotropic antenna systems for satellite applications....

  8. Visidep (TM): A Three-Dimensional Imaging System For The Unaided Eye

    Science.gov (United States)

    McLaurin, A. Porter; Jones, Edwin R.; Cathey, LeConte

    1984-05-01

    The VISIDEP process for creating images in three dimensions on flat screens is suitable for photographic, electrographic and computer generated imaging systems. Procedures for generating these images vary from medium to medium due to the specific requirements of each technology. Imaging requirements for photographic and electrographic media are more directly tied to the hardware than are computer based systems. Applications of these technologies are not limited to entertainment, but have implications for training, interactive computer/video systems, medical imaging, and inspection equipment. Through minor modification the system can provide three-dimensional images with accurately measureable relationships for robotics and adds this factor for future developments in artificial intelligence. In almost any area requiring image analysis or critical review, VISIDEP provides the added advantage of three-dimensionality. All of this is readily accomplished without aids to the human eye. The system can be viewed in full color, false-color infra-red, and monochromatic modalities from any angle and is also viewable with a single eye. Thus, the potential of application for this developing system is extensive and covers the broad spectrum of human endeavor from entertainment to scientific study.

  9. Satellite registration program: a decentralized system to meet customer needs.

    Science.gov (United States)

    Hutchins, J

    1991-01-01

    In summary, if you want to meet your patient, physician and ancillary service needs, then consider registration as a necessary transitional activity and then go about making it secondary to the reason the patient came for healthcare service. The complexities of data collection are for us to be concerned with, not the patient! Also, the physicians will appreciate your efforts on behalf of their patients. You, too, can have an effective Satellite Registration Program if you remember that flexibility, creativity and administrative support are essential to success! Good Luck!

  10. STRUCTURE OF THE SPANISH SYSTEM OF SATELLITE OF COMMUNICATIONS

    Directory of Open Access Journals (Sweden)

    F. Sacristán - Romero

    2007-04-01

    Full Text Available The objectives of satellites HISPASAT are oriented towards the search to satisfy necessities derived from the transport of television and radio signals. It tries the supplying of a basic and safe support of communications for the defence and security of the national territory, the creation of an infrastructure of channels for official networks, routes of data, restoration of connections, rural telephony. Also is wanted to foment the provision of television channels for the Hispanic community in the south and center of America and the broadcasting of services of television for people in general.

  11. Evaluating the Effect of Global Positioning System (GPS) Satellite Clock Error via GPS Simulation

    Science.gov (United States)

    Sathyamoorthy, Dinesh; Shafii, Shalini; Amin, Zainal Fitry M.; Jusoh, Asmariah; Zainun Ali, Siti

    2016-06-01

    This study is aimed at evaluating the effect of Global Positioning System (GPS) satellite clock error using GPS simulation. Two conditions of tests are used; Case 1: All the GPS satellites have clock errors within the normal range of 0 to 7 ns, corresponding to pseudorange error range of 0 to 2.1 m; Case 2: One GPS satellite suffers from critical failure, resulting in clock error in the pseudorange of up to 1 km. It is found that increase of GPS satellite clock error causes increase of average positional error due to increase of pseudorange error in the GPS satellite signals, which results in increasing error in the coordinates computed by the GPS receiver. Varying average positional error patterns are observed for the each of the readings. This is due to the GPS satellite constellation being dynamic, causing varying GPS satellite geometry over location and time, resulting in GPS accuracy being location / time dependent. For Case 1, in general, the highest average positional error values are observed for readings with the highest PDOP values, while the lowest average positional error values are observed for readings with the lowest PDOP values. For Case 2, no correlation is observed between the average positional error values and PDOP, indicating that the error generated is random.

  12. About the Eye

    Medline Plus

    Full Text Available ... The Visual System Your Eyes’ Natural Defenses Eye Health and Safety First Aid ... Your eyes are made up of many different parts that work together to help you see. Check out the ...

  13. New Projects Planed/launched By Cei Wg On Satellite Navigation Systems

    Science.gov (United States)

    Oszczak, S.; Manzoni, G.

    In the paper a short description of main projects on satellite positioning and naviga- tion in CEI countries is given. Special attention is devoted to the activity of members of Working Group on Satellite Navigation Systems. The projects in which they are involved and results of performed experiments can be specified as follows: - EGNOS positioning - the first results in CEI area, - application of various transmission tech- niques to diffusion of DGPS/RTK data from reference stations (SWIFT/DARC, RDS, radiobeacons, UHF transmission), - development of integrated GPS/INS methods for car navigation and GIS purposes, - development of software for integration of satellite vehicle position with numerical maps for car navigation, monitoring and acquisition of terrestrial data for GIS, - elaboration of method and software development for nav- igation and monitoring of aircraft during approaching and landing phase of flight, - elaboration of methods and software for integration of 3D satellite positions of user with Digital Terrain Model (DTM), - development of digital technology for bathy- metric survey with satellite positioning technique; mapping of shallow waters, lakes, rivers and inland water reservoirs, The recently planned studies and experiments cover land, marine and aircraft satellite navigation with EGNOS system in CEI countries. The project of extension of the EGNOS system to the Central and East European region is under preparation. Other important research is conducted on mapping of roads and rails tracks using integrated DGPS/INS techniques.

  14. Research of Multi-Agent System based satellite fault diagnosis technology

    Institute of Scientific and Technical Information of China (English)

    范显峰; 姜兴渭; 黄文虎; 谷吉海

    2002-01-01

    Following the theory of Multi-Agent System (MAS) and using series-wound structure and shunt-wound structure of Agents, the performance of Agent was improved to satisfy the need of satellite fault diagno-sis, and a tridimensional MAS model of satellite fault diagnosis was thus established for the MAS based planardiagnosis system, which decentralizes the whole diagnosing task into subtasks to be performed by different func-tional Agents to make the complicated fault diagnosis very simple and the diagnosis system more intelligent.This method improved the reliability and accuracy of diagnosis and made the maintenance and upgrading of thesatellite fault diagnosis system very easy as well.

  15. Healthy Eyes

    Science.gov (United States)

    ... los Ojos Cómo hablarle a su oculista Healthy Eyes Having a comprehensive dilated eye exam is one ... or contact lenses. What is a comprehensive dilated eye exam? A comprehensive dilated eye exam is a ...

  16. Reliability analysis and design of on-board computer system for small stereo mapping satellite

    Institute of Scientific and Technical Information of China (English)

    马秀娟; 曹喜滨; 马兴瑞

    2002-01-01

    The on-board computer system for a small satellite is required to be high in reliability, light in weight, small in volume and low in power consumption. This paper describes the on-board computer system with the advantages of both centralized and distributed systems, analyzes its reliability, and briefs the key techniques used to improve its reliability.

  17. Suggestion of EFS-small satellite system for impending earthquake forecast

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    In the IAF Congress '92 a multiple small satellite Earth observation system was put forward with sensors of visible and infrared spectrums. The system could shorten the revisiting period so that any place on the world could be observed twice a day. Now we extend the idea to the microwave remote sensing satellite system. The main purpose of the system is the impending forecast of earthquakes. According to the theory and long-time concrete practice of Qiang Zuji through the observation of temperature increase of the low layer of atmosphere and its moving trend caused by some sorts of radiation and gases released from Earth interior, an impending strong earthquake could be predicted in time. As the temperature increase is detected by thermo-infrared spectrum sensors on the meteorological satellites, the observation may be sometimes obstructed by cloud or rain. In the suggested system, mm-wave radiometers are used and those obstructions could be generally overcome.

  18. Research on the new type of multi-functional satellite system for space debris detection

    Science.gov (United States)

    Guo, Linghua; Fu, Qiang; Jiang, Huilin; Xu, Xihe

    2017-05-01

    With the rapid development of space exploration and utilization, orbital debris increases dramatically, leading to great threat to human space activities and spacecraft security. In this paper, a new type of multi-functional space debris satellite system (MSDS) was put forward, which shared main optical system, and possessed functions of multidimensional information detection, polarized remote sensing and high rate transmission. The MSDS system can meet the requirements of detection and identification for the small orbital debris which is 1000km faraway, as well as the requirements of the data transmission by 50 Mbps to 2.5 Gbps@200-1000 km. At the same time, by the method of satellite orbital maneuver and attitude adjusting, the orbital debris information that is real-time, complex and refined, allweather can be acquired and transmitted by the new system. Such new type of multifunctional satellite system can provide important and effective technology for international orbital debris detection.

  19. Effective communication : satellite system poised to improve information flow

    Energy Technology Data Exchange (ETDEWEB)

    Macedo, R.

    2009-01-15

    This paper described a new satellite technology that can be used to transfer important information from offshore oil and gas facilities to decision-makers in distant onshore offices. Cascade Data Services (CDS), a subsidiary of British Columbia-based MDA Corporation, is developing a high-speed low-latency satellite information transfer service which has its roots in the Cascade Smallsat and Ionospheric Polar Explorer (CASSIOPE) mission scheduled for launch in 2009. The technology will enable customers to move thousands of gigabytes to and from anywhere on the planet on a daily basis. CASSIOPE received funding from the Canadian Space Agency and Technology Partnerships Canada. The first payload will be a suite of space science instruments known as the Enhanced Polar Outflow Probe (e-Pop) developed by researchers at the University of Calgary. The second payload will involve a demonstration of the digital courier service model and delivery of large digital data files. CDS has entered into an alliance with O3b Networks funded by Google Inc., Liberty Global Inc., and HSBC Principal Investments, among others. The technological development should improve the flow of information, making oil and gas operations in remote areas more efficient and help cut costs. 1 ref., 2 figs.

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

    Science.gov (United States)

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

    1985-01-01

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

  1. Engineering Tools and Validation Test Beds for New Telecommunication Satellite Multimedia Systems

    Science.gov (United States)

    Foix, V.; Taisant, J.-Ph.; Piau, P.; Thomasson, L.

    2002-01-01

    Satellite telecommunication and broadcasting systems have to adapt to the major evolutions introduced by the emergence of new multimedia services distributed by terrestrial networks. This major adaptation of satellite telecommunication systems implies the use of new technologies and standards, on-board satellites and within the telecommunication ground segment. The deeper interaction between space and ground infrastructures induced by these evolutions also leads to additional system complexity. The definition, design and end-to-end validation of these satellite networks require dedicated engineering tools and validation test beds running the major elements of the telecommunication mission, e.g. on-board and ground equipment implementing the various protocols and algorithms used in the system. Through two programmes called respectively "Atelier Télécom du Futur" and "Multimedia System Validation Test Beds", CNES has been developing since early 2000 an advanced simulation tool and complementary test beds to support engineering activities and cover most of the end-to-end validation needs of these new satellite telecommunication multimedia systems. This communication aims to present the technical objectives, the logic which has led to propose several complementary means, their main characteristics and development status. To end up, the first results provided by these tools and test beds are presented.

  2. Comparing the accuracy of video-oculography and the scleral search coil system in human eye movement analysis.

    Science.gov (United States)

    Imai, Takao; Sekine, Kazunori; Hattori, Kousuke; Takeda, Noriaki; Koizuka, Izumi; Nakamae, Koji; Miura, Katsuyoshi; Fujioka, Hiromu; Kubo, Takeshi

    2005-03-01

    The measurement of eye movements in three dimensions is an important tool to investigate the human vestibular and oculomotor system. The primary methods for three dimensional eye movement measurement are the scleral search coil system (SSCS) and video-oculography (VOG). In the present study, we compare the accuracy of VOG with that of SSCS using an artificial eye. We then analyzed the Y (pitch) and Z (yaw) component of human eye movements during saccades, smooth pursuit and optokinetic nystagmus, and the X (roll) component of human eye movement during the torsional vestibulo-ocular reflex induced by rotation in normal subjects, using simultaneous VOG and SSCS measures. The coefficients of the linear relationship between the angle of a simulated eyeball and the angle measured by both VOG and SSCS was almost unity with y-intercepts close to zero for torsional (X), vertical (Y) and horizontal (Z) movements, indicating that the in vitro accuracy of VOG was similar to that of SSCS. The average difference between VOG and SSCS was 0.56 degrees , 0.78 degrees and 0.18 degrees for the X, Y and Z components of human eye movements, respectively. Both the in vitro and in vivo comparisons demonstrate that VOG has accuracy comparable to SSCS, and is a reliable method for measurement of three dimensions (3D) human eye movements.

  3. [The role of endocannabinoid system in physiological and pathological processes in the eye].

    Science.gov (United States)

    Nadolska, Krystyna; Goś, Roman

    2008-01-01

    Plant of Cannabis sativa/ marihuana except for its psychotropic effects possesses a range of pharmacological properties, that has been utilized for medical purposes over a period of millenia. Investigations concerning biochemical mechanism of action of the main and most active pharmacological compound of Cannabis sativa, cannabinoid 9-THC, contributed to the discovery of cannabinoid receptors both in the central nervous system (CNS) and peripheral tissues, that mediated actions of this substance. The discovery made possible identification of a new, endogenous signaling system reffered to as the endocannabinoid system. Besides cannabinoid receptors CB1 and CB2, the system includes it's endogenic ligands (endocannabinoids) and compounds that participate in their biosynthesis and inactivation. Structure and functioning of the endocannabinoid system is conservative in all vertebrates. It's activation with plant, synthetic and endogenous cannabinoids has an influence on multiple physiological and pathological processes within the eye.

  4. A Novel Method for Optimum Global Positioning System Satellite Selection Based on a Modified Genetic Algorithm.

    Science.gov (United States)

    Song, Jiancai; Xue, Guixiang; Kang, Yanan

    2016-01-01

    In this paper, a novel method for selecting a navigation satellite subset for a global positioning system (GPS) based on a genetic algorithm is presented. This approach is based on minimizing the factors in the geometric dilution of precision (GDOP) using a modified genetic algorithm (MGA) with an elite conservation strategy, adaptive selection, adaptive mutation, and a hybrid genetic algorithm that can select a subset of the satellites represented by specific numbers in the interval (4 ∼ n) while maintaining position accuracy. A comprehensive simulation demonstrates that the MGA-based satellite selection method effectively selects the correct number of optimal satellite subsets using receiver autonomous integrity monitoring (RAIM) or fault detection and exclusion (FDE). This method is more adaptable and flexible for GPS receivers, particularly for those used in handset equipment and mobile phones.

  5. Advanced spacecraft tracking techniques using the Tracking and Data Relay Satellite System /TDRSS/

    Science.gov (United States)

    Teles, J.; Ayres, C.

    1977-01-01

    The TDRSS will consist initially of two geosynchronous satellites and a common ground station at White Sands, New Mexico. According to current schedules, operations are to begin in November 1980. The overall TDRSS will provide high and low bit-rate telemetry, commands, and satellite-to-satellite tracking services. Each Tracking and Data Relay Satellite (TDRS) will have four antenna systems for NASA use. The common ground station at White Sands will have three 18-meter K-band antennas. The tracking equipment at the ground station is required to meet the following specifications: (1) 0.1-radian root-mean-square (rms) phase noise on nondestruct Doppler measurements; (2) 10-nanosecond rms range noise; (3) 50-nanosecond maximum systematic range error. Attention is given to two-way range and Doppler measurements, the bilateration tracking of TDRS, and an experiment using differenced one-way Doppler measurements.

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

    Science.gov (United States)

    Naderi, F.

    1982-01-01

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

  7. Environmental assessment for the satellite power system concept development and evaluation program-electromagnetic systems compatibility

    Energy Technology Data Exchange (ETDEWEB)

    Davis, K A; Grant, W B; Morrison, E L; Juroshek, J R

    1981-01-01

    The EMC analysis addressed only the direct effects of electromagnetic emissions from the SPS on other technological systems. Emissions were defined quite broadly, including not only those from the microwave system, but also thermal blackbody emission and scattered sunlight from the satellite. The analysis is based on the design for an SPS as described in the Reference System Report and some quantitative conclusions, e.g., ranges from rectenna sites at which effects are expected are specific to that design. The methodology and qualitative conclusions, however, apply to an SPS concept using microwave power transmission. Quantitative conclusions have been obtained parametrically and can be adjusted as SPS designs change. The electromagnetic environment that the Reference System would produce, and in which other systems would have to function, is described. As an early part of the EMC Assessment, the problems expected for a hypothetical rectenna site, in the Mojave Desert of southern California, were analyzed in detail. This effort provided an initial quantitative indication of the scope of potential EMC problems and indicated the importance of EMC considerations in rectenna site selection. The results of this analysis are presented. The effects of SPS microwave emissions on important categories of electronic systems and equipment are summarized, with many examples of test results and demonstrated techniques for mitigation of problems encountered. SPS effects on other satellite systems are presented. Astronomical research frequently involves measurement of extremely low levels of electromagnetic radiation and is thus very susceptible to interference. The concerns of both radio astronomy with microwave emissions from SPS and optical astronomy with sunlight scattered from SPS spacecraft are discussed. Summaries of mitigation techniques, cost estimates, and conclusions are presented. (WHK)

  8. InSitu-Eye: oceanological and atmospheric data processing and analyzing system

    Science.gov (United States)

    Stepochkin, Igor E.; Salyuk, Pavel A.; Shmirko, Konstantin A.; Golik, Irina A.; Burov, Denis V.

    2014-11-01

    In this study we introduce brief description and the main approaches used in system development. System is devising with a participation of Pacific Oceanological Institute (FEB RAS), Institute of Automation and Control Processes (FEB RAS) and also Maritime State University, n.a. G.I. Nevelskoy. For many years research team of these institutions carried out a lot of field measurements and collected a lot of remote sensing data, using spectrophotometers, LIDARs, fluorometers. The primary goal of this development - bring all this data together to integrated database and design user-friendly interface to work with. "InSitu-Eye" will perform standard routine operations, such as sampling data according to certain parameters; gridding and timing of data; filtering and quality check of data; visualization. After setting system up and testing it will provide a benefit. At first it gives 24/7 access to "clean", checked "in-situ" data, ready for further research. Also presence of such system gives "converse effect" - it will become necessary to develop strict protocols for measurements carrying out and increase their quality. In future, "InSitu-Eye" can become a platform, connecting research teams for data keeping and exchange.

  9. Dynamical friction and scratches of orbiting satellite galaxies on host systems

    CERN Document Server

    Ogiya, Go

    2015-01-01

    We study the dynamical response of extended systems, hosts, to smaller systems, satellites, orbiting around the hosts using extremely high-resolution N-body simulations with up to one billion particles. This situation corresponds to minor mergers which are ubiquitous in the scenario of hierarchical structure formation in the universe. According to Chandrasekhar (1943), satellites create density wakes along the orbit and the wakes cause a deceleration force on satellites, i.e. dynamical friction. This study proposes an analytical model to predict the dynamical response of hosts in the density distribution and finds not only traditional wakes but also mirror images of over- and underdensities centered on the host. Controlled N-body simulations with high resolutions verify the predictions of the analytical model directly. We apply our analytical model to the expected dynamical response of nearby interacting galaxy pairs, the Milky Way - Large Magellanic Cloud system and the M31 - M33 system.

  10. Dynamical friction and scratches of orbiting satellite galaxies on host systems

    Science.gov (United States)

    Ogiya, Go; Burkert, Andreas

    2016-04-01

    We study the dynamical response of extended systems, hosts, to smaller systems, satellites, orbiting around the hosts using extremely high-resolution N-body simulations with up to one billion particles. This situation corresponds to minor mergers which are ubiquitous in the scenario of hierarchical structure formation in the universe. According to Chandrasekhar, satellites create density wakes along the orbit and the wakes cause a deceleration force on satellites, i.e. dynamical friction. This study proposes an analytical model to predict the dynamical response of hosts as reflected in their density distribution and finds not only traditional wakes but also mirror images of over- and underdensities centred on the host. Our controlled N-body simulations with high resolutions verify the predictions of the analytical model. We apply our analytical model to the expected dynamical response of nearby interacting galaxy pairs, the Milky Way-Large Magellanic Cloud system and the M31-M33 system.

  11. Preliminary design of a satellite observation system for Space Station Freedom

    Science.gov (United States)

    Cabe, Greg (Editor); Gallagher, Chris; Wilson, Brian; Rehfeld, James; Maurer, Alexa; Stern, Dan; Nualart, Jaime; Le, Xuan-Trang

    1992-01-01

    Degobah Satellite Systems (DSS), in cooperation with the University Space Research Association (USRA), NASA - Johnson Space Center (JSC), and the University of Texas, has completed the preliminary design of a satellite system to provide inexpensive on-demand video images of all or any portion of Space Station Freedom (SSF). DSS has narrowed the scope of the project to complement the work done by Mr. Dennis Wells at Johnson Space Center. This three month project has resulted in completion of the preliminary design of AERCAM, the Autonomous Extravehicular Robotic Camera, detailed in this design report. This report begins by providing information on the project background, describing the mission objectives, constraints, and assumptions. Preliminary designs for the primary concept and satellite subsystems are then discussed in detail. Included in the technical portion of the report are detailed descriptions of an advanced imaging system and docking and safing systems that ensure compatibility with the SSF. The report concludes by describing management procedures and project costs.

  12. A simple ship-borne antenna stabilizer for limited area maritime satellite communication systems

    Science.gov (United States)

    Satoh, K.; Nakamae, M.; Mishima, H.

    1984-10-01

    This paper deals with a simple ship-borne antenna stabilizer for use in limited area multi-beam maritime satellite communication systems. A limited area system with high satellite e.i.r.p. is expected to be a more economical satellite system than a global system, because a low-gain ship-borne antenna and a simplified antenna stabilizer can be used. An optimum configuration is proposed for small size and low cost pendulum-type antenna stabilizers which are suitable for low gain ship-borne antennas. Also, a performance evaluation of the stabilizers is discussed using a statistical analysis of ship motion characteristics. Furthermore, fading characteristics of received signal strength due to antenna off-beam fluctuation and sea surface random reflection are experimentally evaluated.

  13. SUMO/FREND: vision system for autonomous satellite grapple

    Science.gov (United States)

    Obermark, Jerome; Creamer, Glenn; Kelm, Bernard E.; Wagner, William; Henshaw, C. Glen

    2007-04-01

    SUMO/FREND is a risk reduction program for an advanced servicing spacecraft sponsored by DARPA and executed by the Naval Center for Space Technology at the Naval Research Laboratory in Washington, DC. The overall program will demonstrate the integration of many techniques needed in order to autonomously rendezvous and capture customer satellites at geosynchronous orbits. A flight-qualifiable payload is currently under development to prove out challenging aspects of the mission. The grappling process presents computer vision challenges to properly identify and guide the final step in joining the pursuer craft to the customer. This paper will provide an overview of the current status of the project with an emphasis on the challenges, techniques, and directions of the machine vision processes to guide the grappling.

  14. Moscow State University near-Earth radiation monitoring satellite system: current status and development

    Science.gov (United States)

    Panasyuk, Mikhail

    2016-07-01

    Radiation measurements using instruments have been designed and manufacturing in the Skobeltsyn Institute of Nuclear Physics of Lomonosov Moscow State University and installed onboard different satellites,i.e. LEO -"Meteor", ISS, GPS - GLONASS, GEO - "Electro" are presented as a basis of radiation monitoring system for control of radiation condition with a goal for to decrease radiation risk of spacecraft's damage on different orbits. Development of this system including radiation measurements onboard "Lomonosov"(LEO) satellite will be presented as well together with future project of multispacecraft LEO system for radiation monitoring.

  15. A Piecewise Affine Hybrid Systems Approach to Fault Tolerant Satellite Formation Control

    DEFF Research Database (Denmark)

    Grunnet, Jacob Deleuran; Larsen, Jesper Abildgaard; Bak, Thomas

    2008-01-01

    In this paper a procedure for modelling satellite formations   including failure dynamics as a piecewise-affine hybrid system is   shown. The formulation enables recently developed methods and tools   for control and analysis of piecewise-affine systems to be applied   leading to synthesis of fault...... tolerant controllers and analysis of   the system behaviour given possible faults.  The method is   illustrated using a simple example involving two satellites trying   to reach a specific formation despite of actuator faults occurring....

  16. A Piecewise Affine Hybrid Systems Approach to Fault Tolerant Satellite Formation Control

    DEFF Research Database (Denmark)

    Grunnet, Jacob Deleuran; Larsen, Jesper Abildgaard; Bak, Thomas

    2008-01-01

    In this paper a procedure for modelling satellite formations   including failure dynamics as a piecewise-affine hybrid system is   shown. The formulation enables recently developed methods and tools   for control and analysis of piecewise-affine systems to be applied   leading to synthesis of fault...... tolerant controllers and analysis of   the system behaviour given possible faults.  The method is   illustrated using a simple example involving two satellites trying   to reach a specific formation despite of actuator faults occurring....

  17. Telecommunication service markets through the year 2000 in relation to millimeter wave satellite systems

    Science.gov (United States)

    Stevenson, S. M.

    1979-01-01

    NASA is currently conducting a series of millimeter wave satellite system market studies to develop 30/20 GHz satellite system concepts that have commercial potential. Four contractual efforts were undertaken: two parallel and independent system studies and two parallel and independent market studies. The marketing efforts are focused on forecasting the total domestic demand for long haul telecommunications services for the 1980-2000 period. Work completed to date and reported in this paper include projections of: geographical distribution of traffic; traffic volume as a function of urban area size; and user identification and forecasted demand.

  18. Effective algorithm for ray-tracing simulations of lobster eye and similar reflective optical systems

    Science.gov (United States)

    Tichý, Vladimír; Hudec, René; Němcová, Šárka

    2016-06-01

    The algorithm presented is intended mainly for lobster eye optics. This type of optics (and some similar types) allows for a simplification of the classical ray-tracing procedure that requires great many rays to simulate. The method presented performs the simulation of a only few rays; therefore it is extremely effective. Moreover, to simplify the equations, a specific mathematical formalism is used. Only a few simple equations are used, therefore the program code can be simple as well. The paper also outlines how to apply the method to some other reflective optical systems.

  19. The anti-fatigue driving system design based on the eye blink detect

    Science.gov (United States)

    Yang, Shuyu; Song, Xin; Zhang, Li; Yu, Jie

    2017-01-01

    Traffic accident is one of the severe social problems in the world, but the appraisal and prevention of the fatigue driving is still a difficult problem that can not be solved. This paper is to study the results of fatigue driving and the existing antifatigue driving products, collecting brain wave with the TGAM (ThinkGear AM) Brain Wave Sensor Chip. We analyze the collected waveform based on eye blink detect algorithm to work out current situation of the driver. According to the analysis results, Sound Module and controllable speed car will make a series of feedback. Finally, an effective Anti- Fatigue Driving System is designed based on all above.

  20. Pre-Launch Radiometric Performance Characterization of the Advanced Technology Microwave Sounder on the Joint Polar Satellite System-1 Satellite

    Science.gov (United States)

    Smith, Craig K.; Kim, Edward; Leslie, R. Vincent; Lyu, Joseph; McCormick, Lisa M.; Anderson, Kent

    2017-01-01

    The Advanced Technology Microwave Sounder (ATMS) is a space-based, cross-track radiometer for operational atmospheric temperature and humidity sounding, utilizing 22 channels over a frequency range from 23 to 183 gigahertz. The ATMS for the Joint Polar Satellite System-1 has undergone two rounds of re-work in 2014-2015 and 2016, following performance issues discovered during and following thermal vacuum chamber (TVAC) testing at the instrument and observatory level. Final shelf-level testing, including measurement of pass band characteristics and spectral response functions, was completed in December 2016. Final instrument-level TVAC testing and calibration occurred during February 2017. Here we will describe the instrument-level TVAC calibration process, and illustrate with results from the final TVAC calibration effort.

  1. Customer premise service study for 30/20 GHz satellite system

    Science.gov (United States)

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

    1983-01-01

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

  2. The eye and visual system in pregnancy, what to expect? An in-depth review

    Directory of Open Access Journals (Sweden)

    Khawla Abu Samra

    2013-01-01

    Full Text Available Pregnancy represents a real challenge to all body systems. Physiological changes can involve any of the body organs including the eye and visual system. The ocular effect of pregnancy involves a wide spectrum of physiologic and pathologic changes. The latter might be presenting for the first time during pregnancy such as corneal melting and corneal ectasia, or an already existing ocular pathologies that are modified by pregnancy such as diabetic retinopathy and glaucoma. In addition, pregnancy can affect vision through systemic disease that are either specific to the pregnant state itself such as the pre-eclampsia/eclampsia and Sheehan′s syndrome, or systemic diseases that occur more frequently in relation to pregnancy such as Graves′ disease, idiopathic intracranial hypertension, anti-phospholipid syndrome, and disseminated intravascular coagulation.

  3. The eye and visual system in pregnancy, what to expect? An in-depth review

    Science.gov (United States)

    Samra, Khawla Abu

    2013-01-01

    Pregnancy represents a real challenge to all body systems. Physiological changes can involve any of the body organs including the eye and visual system. The ocular effect of pregnancy involves a wide spectrum of physiologic and pathologic changes. The latter might be presenting for the first time during pregnancy such as corneal melting and corneal ectasia, or an already existing ocular pathologies that are modified by pregnancy such as diabetic retinopathy and glaucoma. In addition, pregnancy can affect vision through systemic disease that are either specific to the pregnant state itself such as the pre-eclampsia/eclampsia and Sheehan's syndrome, or systemic diseases that occur more frequently in relation to pregnancy such as Graves’ disease, idiopathic intracranial hypertension, anti-phospholipid syndrome, and disseminated intravascular coagulation. PMID:24082665

  4. [Drug delivery systems to target the anterior segment of the eye: fundamental bases and clinical applications].

    Science.gov (United States)

    Behar-Cohen, F

    2002-05-01

    The development of new drug delivery systems to target the anterior segment of the eye may offer many advantages: to increase the biodisponibility of the drug, to allow the penetration of drug that cannot be formulated as solutions, to obtain constant and sustained drug release, to achieve higher local concentrations without systemic effects, to target more specifically one tissue or cell type, to reduce the frequency of instillation and therefore increase the observance and comfort of the patient while reducing side effects of frequent instillation. Several approaches are developed, aiming to increase the corneal contact time by modified formulation or reservoir systems, or by increasing the tissue permeability using iontophoresis. To date, no ocular drug delivery system is ideal for all purposes. To maximize treatment efficacy, careful evaluation of the specific pathological condition, the targeted Intraocular tissue and the location of the most severe pathology must be made before selecting the method of delivery most suitable for each individual patient.

  5. Ocean tidal dissipation and its role in solar system satellite evolution

    Science.gov (United States)

    Chen, Erinna M.

    The history of satellites in the Solar System is quite diverse. For example, satellites like Io and Enceladus exhibit active volcanism currently, while satellites like Ganymede and Tethys show signs of geologic activity in the deep past, but not at present. The energy dissipated by tides has been identified as a major heat source for satellites, but calculations for satellite tidal dissipation primarily focus on dissipation in a solid layer, such as the ice shell. An exciting discovery of the NASA spacecraft missions Galileo and Cassini is that global-scale, deep, liquid water oceans are present on many of the outer Solar System satellites. Tyler (2008) suggested that tidal dissipation due to flow in these oceans could potentially be a significant and previously neglected source of heat. However, a critical free parameter in Tyler's model is the effective turbulent viscosity in the ocean. The value of the effective viscosity is unconstrained and because the amount of tidal dissipation scales with this parameter, the amount of ocean tidal dissipation is also unconstrained. In order to address this uncertainty, we developed a numerical model that solves the shallow-water equations on a spherical shell and includes a nonlinear bottom friction parameterization for viscous dissipation. The bottom friction coefficient has a well-established value in the terrestrial literature; however, the nonlinearity of this term in the equations of motion make the model far more computationally expensive than a model that includes turbulent viscosity. Thus, we provide numerically-derived scalings that map the bottom friction coefficient and satellite parameters to an equivalent effective turbulent viscosity. Because tides depend on both the thermal structure of a satellite as well as characteristics of the satellite's orbit, models that couple thermal and orbital evolution are required to understand the history of a satellite. We use our numerically-derived scalings to adapt a coupled

  6. Optimality of incompletely measurable active and passive attitude control systems. [for satellites

    Science.gov (United States)

    Schiehlen, W.; Popp, K.

    1973-01-01

    Passive attitude control systems and active systems with incomplete state measurements are only suboptimal systems in the sense of optimal control theory, since optimal systems require complete state measurements or state estimations. An optimal system, then, requires additional hardware (especially in the case of flexible spacecraft) which results in higher costs. Therefore, it is a real engineering problem to determine how much an optimal system exceeds the suboptimal system, or in other words, what is the suboptimal system's degree of optimality. The problem will be treated in three steps: (1) definition of the degree of optimality for linear, time-invariant systems; (2) a computation method using the quadratic cost functional; (3) application to a gravity-gradient stabilized three-body satellite and a spinning flexible satellite.

  7. Observation of new satellites in Cs-Ar system using resonance ionization spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Nayfeh, M.H.; Hurst, G.S.; Payne, M.G.; Young, J.P.

    1978-07-31

    The absorption line shape of Cs-Ar system is recorded using two-photon ionization of the system with Cs(7P) as an intermediate state. New satellite structures in the wings of Cs(7P) are observed which were not resolved in previous absorption measurements. Also the absolute absorption cross section in the blue wing is measured.

  8. System for electronic transformation and geographic correlation of satellite television information. [cloud cover photography

    Science.gov (United States)

    Dubenskiy, V. P.; Nemkovskiy, B. L.; Rodionov, B. N.

    1974-01-01

    An electronic transformation and correlation system has been developed for the Meteor space weather system which provides transformation and scaling of the original picture, accounts for satellite flight altitude and inclinations of the optical axes of the transmitting devices, and simultaneously superposes the geographical coordinate grid on the transformed picture.

  9. 17th East European Conference on Advances in Databases and Information Systems and Associated Satellite Events

    CERN Document Server

    Cerquitelli, Tania; Chiusano, Silvia; Guerrini, Giovanna; Kämpf, Mirko; Kemper, Alfons; Novikov, Boris; Palpanas, Themis; Pokorný, Jaroslav; Vakali, Athena

    2014-01-01

    This book reports on state-of-art research and applications in the field of databases and information systems. It includes both fourteen selected short contributions, presented at the East-European Conference on Advances in Databases and Information Systems (ADBIS 2013, September 1-4, Genova, Italy), and twenty-six papers from ADBIS 2013 satellite events. The short contributions from the main conference are collected in the first part of the book, which covers a wide range of topics, like data management, similarity searches, spatio-temporal and social network data, data mining, data warehousing, and data management on novel architectures, such as graphics processing units, parallel database management systems, cloud and MapReduce environments. In contrast, the contributions from the satellite events are organized in five different parts, according to their respective ADBIS satellite event: BiDaTA 2013 - Special Session on Big Data: New Trends and Applications); GID 2013 – The Second International Workshop ...

  10. Spacecraft flight control system design selection process for a geostationary communication satellite

    Science.gov (United States)

    Barret, C.

    1992-01-01

    The Earth's first artificial satellite, Sputnik 1, slowly tumbled in orbit. The first U.S. satellite, Explorer 1, also tumbled out of control. Now, as we launch the Mars observer and the Cassini spacecraft, stability and control have become higher priorities. The flight control system design selection process is reviewed using as an example a geostationary communication satellite which is to have a life expectancy of 10 to 14 years. Disturbance torques including aerodynamic, magnetic, gravity gradient, solar, micrometeorite, debris, collision, and internal torques are assessed to quantify the disturbance environment so that the required compensating torque can be determined. Then control torque options, including passive versus active, momentum control, bias momentum, spin stabilization, dual spin, gravity gradient, magnetic, reaction wheels, control moment gyros, nutation dampers, inertia augmentation techniques, three-axis control, reactions control system (RCS), and RCS sizing, are considered. A flight control system design is then selected and preliminary stability criteria are met by the control gains selection.

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

    Science.gov (United States)

    Carter, P.; Beach, M. A.

    1993-01-01

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

  12. Computational methodology to predict satellite system-level effects from impacts of untrackable space debris

    Science.gov (United States)

    Welty, N.; Rudolph, M.; Schäfer, F.; Apeldoorn, J.; Janovsky, R.

    2013-07-01

    This paper presents a computational methodology to predict the satellite system-level effects resulting from impacts of untrackable space debris particles. This approach seeks to improve on traditional risk assessment practices by looking beyond the structural penetration of the satellite and predicting the physical damage to internal components and the associated functional impairment caused by untrackable debris impacts. The proposed method combines a debris flux model with the Schäfer-Ryan-Lambert ballistic limit equation (BLE), which accounts for the inherent shielding of components positioned behind the spacecraft structure wall. Individual debris particle impact trajectories and component shadowing effects are considered and the failure probabilities of individual satellite components as a function of mission time are calculated. These results are correlated to expected functional impairment using a Boolean logic model of the system functional architecture considering the functional dependencies and redundancies within the system.

  13. Automated grading system for evaluation of ocular redness associated with dry eye

    Directory of Open Access Journals (Sweden)

    Rodriguez JD

    2013-06-01

    Full Text Available John D Rodriguez,1 Patrick R Johnston,1 George W Ousler III,1 Lisa M Smith,1 Mark B Abelson1,21Ora, Inc, Andover, MA, USA; 2Department of Ophthalmology, Harvard Medical School, Boston, MA, USABackground: We have observed that dry eye redness is characterized by a prominence of fine horizontal conjunctival vessels in the exposed ocular surface of the interpalpebral fissure, and have incorporated this feature into the grading of redness in clinical studies of dry eye.Aim: To develop an automated method of grading dry eye-associated ocular redness in order to expand on the clinical grading system currently used.Methods: Ninety nine images from 26 dry eye subjects were evaluated by five graders using a 0–4 (in 0.5 increments dry eye redness (Ora CalibraTM Dry Eye Redness Scale [OCDER] scale. For the automated method, the Opencv computer vision library was used to develop software for calculating redness and horizontal conjunctival vessels (noted as "horizontality". From original photograph, the region of interest (ROI was selected manually using the open source ImageJ software. Total average redness intensity (Com-Red was calculated as a single channel 8-bit image as R − 0.83G − 0.17B, where R, G and B were the respective intensities of the red, green and blue channels. The location of vessels was detected by normalizing the blue channel and selecting pixels with an intensity of less than 97% of the mean. The horizontal component (Com-Hor was calculated by the first order Sobel derivative in the vertical direction and the score was calculated as the average blue channel image intensity of this vertical derivative. Pearson correlation coefficients, accuracy and concordance correlation coefficients (CCC were calculated after regression and standardized regression of the dataset.Results: The agreement (both Pearson's and CCC among investigators using the OCDER scale was 0.67, while the agreement of investigator to computer was 0.76. A multiple

  14. Neptune's small satellites

    Science.gov (United States)

    Thomas, P.

    1992-04-01

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

  15. Comprehensive Comparisons of Satellite Data, Signals, and Measurements between the BeiDou Navigation Satellite System and the Global Positioning System

    Directory of Open Access Journals (Sweden)

    Shau-Shiun Jan

    2016-05-01

    Full Text Available The Chinese BeiDou navigation satellite system (BDS aims to provide global positioning service by 2020. The combined use of BDS and Global Positioning System (GPS is proposed to provide navigation service with more stringent requirements. Actual satellite data, signals and measurements were collected for more than one month to analyze the positioning service qualities from both BDS and GPS. In addition to the conversions of coordinate and timing system, five data quality analysis (DQA methods, three signal quality analysis (SQA methods, and four measurement quality analysis (MQA methods are proposed in this paper to improve the integrated positioning performance of BDS and GPS. As shown in the experiment results, issues related to BDS and GPS are resolved by the above proposed quality analysis methods. Thus, the anomalies in satellite data, signals and measurements can be detected by following the suggested resolutions to enhance the positioning performance of the combined use of BDS and GPS in the Asia Pacific region.

  16. About the Eye

    Medline Plus

    Full Text Available ... other programs with respect to blinding eye diseases, visual disorders, mechanisms of visual function, preservation of sight, and the special health ... Eye Ask a Scientist Video Series Glossary The Visual System Your Eyes’ Natural Defenses Eye Health and ...

  17. About the Eye

    Medline Plus

    Full Text Available ... other programs with respect to blinding eye diseases, visual disorders, mechanisms of visual function, preservation of sight, and the special health ... Eye Ask a Scientist Video Series Glossary The Visual System Your Eyes’ Natural Defenses Eye Health and ...

  18. Keck Adaptive Optics Observations of Neptune's Ring and Satellite Keck Adaptive Optics Observations of Neptune's Ring and Satellite System

    Science.gov (United States)

    de Pater, I.; Gibbard, S.; Martin, S.; Marchis, F.; Roe, H. G.; Macintosh, B.

    2003-05-01

    We observed Neptune, its satellites and ring system on UT 27 and 28 July 2002, with NIRC2 on the 10-m Keck II telescope at 2.2 micron. The total field of view was 10". Each image was integrated for 1 minute; on the first day we had a total of 18 frames, and 33 images on the second day, each spread out over a time interval of 1-2 hours. The complete Adams and Le Verrier rings are visible on each day, after combining all images. In the regions away from the ring arcs, we find that the Le Verrier ring is brighter (up to 20-40%) than the Adams ring. The ring arcs are readily apparent in combinations of the data that take into account Keplerian motion. The ring arc positions are in close agreement with Nicholson et al's (1995) result, as in HST/NICMOS images (Dumas et al. 2002). The Egalite ring has broadened even more since observed with HST/NICMOS in 1998, and is clearly the brightest ring arc. Liberte has decreased in intensity since Voyager and NICMOS. Courage was extremely faint in our images. The satellites Proteus, Larissa, Galatea and Despina are easily seen on individual frames. Thalassa is detected after properly shifting/rotating and adding several frames. This is the first time since the Voyager flybys that Thalassa is detected. Preliminary astrometric measurements suggest the satellites Larissa and Galathea, relative to Proteus, to be off from their nominal (JPL Horizons) positions by 0.3", and Despina by 0.1". Recent results indicate that Proteus is offset by 0.1" compared to Triton (Martins et al. 2003). Preliminary I/F values are 0.06 for Proteus, 0.045 for Larissa and Galatea, and 0.03 for Despina and Thalassa. These observations were supported by the National Science Foundation Science and Technology Center for Adaptive Optics, managed by the University of California at Santa Cruz under cooperative agreement No. AST-9876783

  19. 47 CFR 25.278 - Additional coordination obligation for non-geostationary and geostationary satellite systems in...

    Science.gov (United States)

    2010-10-01

    ... service for their feeder link operations shall coordinate their operations with licensees of geostationary...-geostationary satellite systems for feeder link operations shall coordinate their operations with the...

  20. The C3PO project: a laser communication system concept for small satellites

    Science.gov (United States)

    d'Humières, Benoît; Esmiller, Bruno; Gouy, Yann; Steck, Emilie; Quintana, Crisanto; Faulkner, Graham; O'Brien, Dominic; Sproll, Fabian; Wagner, Paul; Hampf, Daniel; Riede, Wolfgang; Salter, Michael; Wang, Qin; Platt, Duncan; Jakonis, Darius; Piao, Xiaoyu; Karlsson, Mikael; Oberg, Olof; Petermann, Ingemar; Michalkiewicz, Aneta; Krezel, Jerzy; Debowska, Anna; Thueux, Yoann

    2017-02-01

    The satellite market is shifting towards smaller (micro and nanosatellites), lowered mass and increased performance platforms. Nanosatellites and picosatellites have been used for a number of new, innovative and unique payloads and missions. This trend requires new concepts for a reduced size, a better performance/weight ratio and a reduction of onboard power consumption. In this context, disruptive technologies, such as laser-optical communication systems, are opening new possibilities. This paper presents the C3PO1 system, "advanced Concept for laser uplink/ downlink CommuniCation with sPace Objects", and the first results of the development of its key technologies. This project targets the design of a communications system that uses a ground-based laser to illuminate a satellite, and a Modulating Retro-Reflector (MRR) to return a beam of light modulated by data to the ground. This enables a downlink, without a laser source on the satellite. This architecture suits well to small satellite applications so as high data rates are potentially provided with very low board mass. C3PO project aims to achieve data rates of 1Gbit/s between LEO satellites and Earth with a communication payload mass of less than 1kilogram. In this paper, results of the initial experiments and demonstration of the key technologies will be shown.

  1. Performance analysis of GPS augmentation using Japanese Quasi-Zenith Satellite System

    Science.gov (United States)

    Wu, F.; Kubo, N.; Yasuda, A.

    2004-01-01

    The current GPS satellite constellation provides limited availability and reliability for a country like Japan where mountainous terrain and urban canyons do not allow a clear skyline to the horizon. At present, the Japanese Quasi-Zenith Satellite System (QZSS) is under investigation through a government-private sector cooperation. QZSS is considered a multi-mission satellite system, as it is able to provide communication, broadcasting and positioning services for mobile users in a specified region with high elevation angle. The performance of a Global Navigation Satellite System (GNSS) can be quantified by availability, accuracy, reliability and integrity. This paper focuses on availability, accuracy and reliability of GPS with and without augmentation using QZSS. The availability, accuracy and reliability of GPS only and augmented GPS using QZSS in the Asia-Pacific and Australian area is studied by software simulation. The simulation results are described by the number of visible satellites as a measure of availability, geometric dilution of precision as a measure of accuracy and minimal detectable bias, and bias-to-noise rate as a measure of reliability, with spatial and temporal variations. It is shown that QZSS does not only improve the availability and accuracy of GPS positioning, but also enhances the reliability of GPS positioning in Japan and its neighboring area.

  2. Optimization of Power Allocation for Multiusers in Multi-Spot-Beam Satellite Communication Systems

    Directory of Open Access Journals (Sweden)

    Heng Wang

    2014-01-01

    Full Text Available In recent years, multi-spot-beam satellite communication systems have played a key role in global seamless communication. However, satellite power resources are scarce and expensive, due to the limitations of satellite platform. Therefore, this paper proposes optimizing the power allocation of each user in order to improve the power utilization efficiency. Initially the capacity allocated to each user is calculated according to the satellite link budget equations, which can be achieved in the practical satellite communication systems. The problem of power allocation is then formulated as a convex optimization, taking account of a trade-off between the maximization of the total system capacity and the fairness of power allocation amongst the users. Finally, an iterative algorithm based on the duality theory is proposed to obtain the optimal solution to the optimization. Compared with the traditional uniform resource allocation or proportional resource allocation algorithms, the proposed optimal power allocation algorithm improves the fairness of power allocation amongst the users. Moreover, the computational complexity of the proposed algorithm is linear with both the numbers of the spot beams and users. As a result, the proposed power allocation algorithm is easy to be implemented in practice.

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

    Science.gov (United States)

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

    1988-01-01

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

  4. Preliminary environmental assessment for the Satellite Power System (SPS). Revision 1. Volume 2. Detailed assessment

    Energy Technology Data Exchange (ETDEWEB)

    1980-01-01

    The Department of Energy (DOE) is considering several options for generating electrical power to meet future energy needs. The satellite power system (SPS), one of these options, would collect solar energy through a system of satellites in space and transfer this energy to earth. A reference system has been described that would convert the energy to microwaves and transmit the microwave energy via directive antennas to large receiving/rectifying antennas (rectennas) located on the earth. At the rectennas, the microwave energy would be converted into electricity. The potential environmental impacts of constructing and operating the satellite power system are being assessed as a part of the Department of Energy's SPS Concept Development and Evaluation Program. This report is Revision I of the Preliminary Environmental Assessment for the Satellite Power System published in October 1978. It refines and extends the 1978 assessment and provides a basis for a 1980 revision that will guide and support DOE recommendations regarding future SPS development. This is Volume 2 of two volumes. It contains the technical detail suitable for peer review and integrates information appearing in documents referenced herein. The key environmental issues associated with the SPS concern human health and safety, ecosystems, climate, and electromagnetic systems interactions. In order to address these issues in an organized manner, five tasks are reported: (I) microwave-radiation health and ecological effects; (II) nonmicrowave health and ecological effectss; (III) atmospheric effects; (IV) effects on communication systems due to ionospheric disturbance; and (V) electromagnetic compatibility. (WHK)

  5. Study on algorithm of dynamic uncalibrated eye-in-hand visual servoing system

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Currently, most visual servoing system must be calibrated, while it is impossible to calibrate cameras and robot models precisely in industrial practice, so a novel dynamic uncalibrated eye-in-hand visual servoing system of tracking a moving target is proposed. The method does not require calibration of camera and robot kinematic models. Vision guided algorithm for tracking dynamic image is developed through minimizing nonlinear objective function. For the large residual has not been approximated in dynamic environment and the change of composite image Jacobian with time increment has not been computed in visual servoing system now,large residuals are dynamic approximated and the change of composite image Jacobian at each iterative step is computed.Simulation results demonstrate the validity of these approaches.

  6. A System to Detect Residential Area in Multispectral Satellite Images

    Directory of Open Access Journals (Sweden)

    Seyfallah Bouraoui

    2011-11-01

    Full Text Available In this paper, we propose a new solution to extract complex structures from High-Resolution (HR remote-sensing images. We propose to represent shapes and there relations by using region adjacency graphs. They are generated automatically from the segmented images. Thus, the nodes of the graph represent shape like houses, streets or trees, while arcs describe the adjacency relation between them. In order to be invariant to transformations such as rotation and scaling, the extraction of objects of interest is done by combining two techniques: one based on roof color to detect the bounding boxes of houses, and one based on mathematical morphology notions to detect streets. To recognize residential areas, a model described by a regular language is built. The detection is achieved by looking for a path in the region adjacency graph, which can be recognized as a word belonging to the description language. Our algorithm was tested with success on images from the French satellite SPOT 5 representing the urban area of Strasbourg (France at different spatial resolution.

  7. The geo-control system for station keeping and colocation of geostationary satellites

    Science.gov (United States)

    Montenbruck, O.; Eckstein, M. C.; Gonner, J.

    1993-01-01

    GeoControl is a compact but powerful and accurate software system for station keeping of single and colocated satellites, which has been developed at the German Space Operations Center. It includes four core modules for orbit determination (including maneuver estimation), maneuver planning, monitoring of proximities between colocated satellites, and interference and event prediction. A simple database containing state vector and maneuver information at selected epochs is maintained as a central interface between the modules. A menu driven shell utilizing form screens for data input serves as the central user interface. The software is written in Ada and FORTRAN and may be used on VAX workstations or mainframes under the VMS operating system.

  8. A CDMA architecture for a Ka-band Personal Access Satellite System

    Science.gov (United States)

    Motamedi, Masoud; Sue, Miles K.

    1990-01-01

    A Code Division Multiple Access (CDMA) architecture is currently being studied for use in a Ka-band Personal Access Satellite System (PASS). The complete architecture consisting of block diagrams of the user terminal, the supplier station, the network management center, and the satellite is described along with the access methods and frequency/time plans. The complexity of developing this system using the CDMA architecture is compared to that of a Frequency Division Multiple Access (FDMA) architecture. The inherent advantages and disadvantages of the two architectures are compared and their respective capacities are discussed.

  9. The FODA-TDMA satellite access scheme - Presentation, study of the system, and results

    Science.gov (United States)

    Celandroni, Nedo; Ferro, Erina

    1991-12-01

    A description is given of FODA-TDMA, a satellite access scheme designed for mixed traffic. The study of the system is presented and the choice of some parameters is justified. A simplified analytic solution is found, describing the steady-state behavior of the system. Some results of the simulation tests for an already existing hardware environment are also presented for the channel speeds of 2 and 8 Mb/s, considering both the stationary and the transient cases. The results of the experimentation at 2 Mb/s on the satellite Eutelsat-F2 are also presented and compared with the results of the simulation.

  10. A novel lobster-eye imaging system based on Schmidt-type objective for X-ray-backscattering inspection

    Science.gov (United States)

    Xu, Jie; Wang, Xin; Zhan, Qi; Huang, Shengling; Chen, Yifan; Mu, Baozhong

    2016-07-01

    This paper presents a novel lobster-eye imaging system for X-ray-backscattering inspection. The system was designed by modifying the Schmidt geometry into a treble-lens structure in order to reduce the resolution difference between the vertical and horizontal directions, as indicated by ray-tracing simulations. The lobster-eye X-ray imaging system is capable of operating over a wide range of photon energies up to 100 keV. In addition, the optics of the lobster-eye X-ray imaging system was tested to verify that they meet the requirements. X-ray-backscattering imaging experiments were performed in which T-shaped polymethyl-methacrylate objects were imaged by the lobster-eye X-ray imaging system based on both the double-lens and treble-lens Schmidt objectives. The results show similar resolution of the treble-lens Schmidt objective in both the vertical and horizontal directions. Moreover, imaging experiments were performed using a second treble-lens Schmidt objective with higher resolution. The results show that for a field of view of over 200 mm and with a 500 mm object distance, this lobster-eye X-ray imaging system based on a treble-lens Schmidt objective offers a spatial resolution of approximately 3 mm.

  11. Perceived visual motion as effective stimulus to pursuit eye movement system

    Science.gov (United States)

    Yasui, S.; Young, L. R.

    1975-01-01

    Human eye tracking of a foveal afterimage during angular head oscillation in the dark produced smooth eye movements exceeding those for normal vestibular nystagmus, and a reduction in the frequency of the fast phase component of nystagmus eye movements. These results may support a closed loop extension of the corollary discharge theory, with oculomotor commands based on perceived object velocity.

  12. Eye proprioception may provide real time eye position information.

    Science.gov (United States)

    Wang, Jing; Pan, Yujun

    2013-03-01

    Because of the frequency of eye movements, online knowledge of eye position is crucial for the accurate spatial perception and behavioral navigation. Both the internal monitoring signal (corollary discharge) of eye movements and the eye proprioception signal are thought to contribute to the localization of the eye position in the orbit. However, the functional role of these two eye position signals in spatial cognition has been disputed for more than a century. The predominant view proposes that the online analysis of eye position is exclusively provided by the corollary discharge signal, while the eye proprioception signal only plays a role in the long-term calibration of the oculomotor system. However, increasing evidence from recent behavioral and physiological studies suggests that the eye proprioception signal may play a role in the online monitoring of eye position. The purpose of this review is to discuss the feasibility and possible function of the eye proprioceptive signal for online monitoring of eye position.

  13. Impact-driven ice loss in outer Solar System satellites: Consequences for the Late Heavy Bombardment

    Science.gov (United States)

    Nimmo, F.; Korycansky, D. G.

    2012-05-01

    We use recent hydrodynamical results (Kraus, R.G., Senft, L.G., Stewart, S.S. [2011]. Icarus, 214, 724-738) for the production of water vapor by hypervelocity impacts on ice targets to assess which present-day major satellites of Jupiter, Saturn, and Uranus would have lost mass due to impact vaporization during an era of massive bombardment similar to the Late Heavy Bombardment in the inner Solar System. Using impactor populations suggested by recent work (Charnoz, S., Morbidelli, A., Dones, L., Salmon, J. [2009]. Icarus, 199, 413-428; Barr, A.C., Canup, R.M. [2010]. Nat. Geosci., 3, 164-167), we find that several satellites would have lost all their HO; we suggest that the most likely resolution of this paradox is that either the LHB delivered ≈10 times less mass to the outer Solar System than predicted by the standard Nice Model, or that the inner satellites formed after the LHB.

  14. Long-term evolution of the inclined geosynchronous orbit in Beidou Navigation Satellite System

    Science.gov (United States)

    Tang, Jingshi; Hou, Xiyun; Liu, Lin

    2017-02-01

    China's Beidou Navigation Satellite System (BDS), unlike other navigation satellite systems, uses several inclined geosynchronous orbits (IGSO) to enhance the accuracy of regional or global navigation. In order to maintain a safe space environment in the vicinity of its operational orbit, it is necessary that the decommissioned satellites be well disposed of. To understand the underlying dynamics that affect the BDS IGSO, we study this problem from two aspects. In this paper, we first theoretically analyze the problem using the simplified models with 1 and 2 degrees of freedoms (1-/2-dof). Then we extensively investigate the numerically propagated orbits for 200 and 1000 years, applying the results from these simplified models and seeking proper explanations for the underlying dynamics. We especially focus on the eccentricity evolution, which is a major concern regarding the collision hazard. We expect to understand the underlying dynamics governing the long-term evolution of BDS IGSO and gain helpful insight into future disposal strategies.

  15. Use of a geosynchronous satellite within the SARSAT/COSPAS system

    Science.gov (United States)

    Goudy, P.; Ludwig, D.; Trudell, B.

    1982-01-01

    Operational characteristics of combined LEO SARSAT/COSPAS and GEO spacecraft for localization of aircraft and seacraft emitting distress signals are described. Although 121.5 MHz capability is now included in all SARSAT/COSPAS satellites, limitations on the number of simultaneous signals which can be processed at that frequency due to atmospheric noise indicates the employment of the 406 MHz band. Additionally, the necessity for on-board storage for later transmission when the satellites are in a favorable position is leading to the implementation of GEO stationed relays for real-time transmission and processing of distress signals. Six NOAA spacecraft and two Soviet satellites are planned, with a completed system offering high detection probability, position location, worldwide coverage, coded messages, and high capacity (406 MHz). A significant factor in use of a GEO relay system is noted to be the signal to noise temperature of the repeater.

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

    Science.gov (United States)

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

    2002-01-01

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

  17. SacLab: A toolbox for saccade analysis to increase usability of eye tracking systems in clinical ophthalmology practice.

    Science.gov (United States)

    Cercenelli, Laura; Tiberi, Guido; Corazza, Ivan; Giannaccare, Giuseppe; Fresina, Michela; Marcelli, Emanuela

    2017-01-01

    Many open source software packages have been recently developed to expand the usability of eye tracking systems to study oculomotor behavior, but none of these is specifically designed to encompass all the main functions required for creating eye tracking tests and for providing the automatic analysis of saccadic eye movements. The aim of this study is to introduce SacLab, an intuitive, freely-available MATLAB toolbox based on Graphical User Interfaces (GUIs) that we have developed to increase the usability of the ViewPoint EyeTracker (Arrington Research, Scottsdale, AZ, USA) in clinical ophthalmology practice. SacLab consists of four processing modules that enable the user to easily create visual stimuli tests (Test Designer), record saccadic eye movements (Data Recorder), analyze the recorded data to automatically extract saccadic parameters of clinical interest (Data Analyzer) and provide an aggregate analysis from multiple eye movements recordings (Saccade Analyzer), without requiring any programming effort by the user. A demo application of SacLab to carry out eye tracking tests for the analysis of horizontal saccades was reported. We tested the usability of SacLab toolbox with three ophthalmologists who had no programming experience; the ophthalmologists were briefly trained in the use of SacLab GUIs and were asked to perform the demo application. The toolbox gained an enthusiastic feedback from all the clinicians in terms of intuitiveness, ease of use and flexibility. Test creation and data processing were accomplished in 52±21s and 46±19s, respectively, using the SacLab GUIs. SacLab may represent a useful tool to ease the application of the ViewPoint EyeTracker system in clinical routine in ophthalmology. Copyright © 2016 Elsevier Ltd. All rights reserved.

  18. Ionizing radiation risks to satellite power systems (SPS) workers

    Energy Technology Data Exchange (ETDEWEB)

    Lyman, J.T.; Ainsworth, E.J.; Alpen, E.L.; Bond, V.; Curtis, S.B.; Fry, R.J.M.; Jackson, K.L.; Nachtwey, S.; Sondhaus, C.; Tobias, C.A.; Fabrikant, J.I.

    1980-11-01

    The radiation risks to the health of workers who will construct and maintain solar power satellites in the space environment were examined. For ionizing radiation, the major concern will be late or delayed health effects, particularly the increased risk of radiation-induced cancer. The estimated lifetime risk for cancer is 0.8 to 5.0 excess deaths per 10,000 workers per rad of exposure. Thus, for example, in 10,000 workers who completed ten missions with an exposure of 40 rem per mission, 320 to 2000 additional deaths in excess of the 1640 deaths from normally occurring cancer, would be expected. These estimates would indicate a 20 to 120% increase in cancer deaths in the worker-population. The wide range in these estimates stems from the choice of the risk-projection model and the dose-response relationsip. The choice between a linear and a linear-quadratic dose-response model may alter the risk estimate by a factor of about two. The method of analysis (e.g., relative vs absolute risk model) can alter the risk estimate by an additional factor of three. Choosing different age and sex distributions can further change the estimate by another factor of up to three. The potential genetic consequences could be of significance, but at the present time, sufficient information on the age and sex distribution of the worker population is lacking for precise estimation of risk. The potential teratogenic consequences resulting from radiation are considered significant. Radiation exposure of a pregnant worker could result in developmental abnormalities.

  19. Experimental Study on the Precise Orbit Determination of the BeiDou Navigation Satellite System

    Directory of Open Access Journals (Sweden)

    Jens Wickert

    2013-03-01

    Full Text Available The regional service of the Chinese BeiDou satellite navigation system is now in operation with a constellation including five Geostationary Earth Orbit satellites (GEO, five Inclined Geosynchronous Orbit (IGSO satellites and four Medium Earth Orbit (MEO satellites. Besides the standard positioning service with positioning accuracy of about 10 m, both precise relative positioning and precise point positioning are already demonstrated. As is well known, precise orbit and clock determination is essential in enhancing precise positioning services. To improve the satellite orbits of the BeiDou regional system, we concentrate on the impact of the tracking geometry and the involvement of MEOs, and on the effect of integer ambiguity resolution as well. About seven weeks of data collected at the BeiDou Experimental Test Service (BETS network is employed in this experimental study. Several tracking scenarios are defined, various processing schemata are designed and carried out; and then, the estimates are compared and analyzed in detail. The results show that GEO orbits, especially the along-track component, can be significantly improved by extending the tracking network in China along longitude direction, whereas IGSOs gain more improvement if the tracking network extends in latitude. The involvement of MEOs and ambiguity-fixing also make the orbits better.

  20. Satellite Monitoring Systems for Shipping and Offshore Oil and Gas Industry in the Baltic Sea

    Directory of Open Access Journals (Sweden)

    Kostianoy A.G.

    2015-06-01

    Full Text Available Shipping activities, oil production and transport in the sea, oil handled in harbors, construction and exploitation of offshore oil and gas pipelines have a number of negative impacts on the marine environment and coastal zone of the seas. In 2004-2014 we elaborated several operational satellite monitoring systems for oil and gas companies in Russia and performed integrated satellite monitoring of the ecological state of coastal waters in the Baltic, Black, Caspian, and Kara seas, which included observation of oil pollution, suspended matter, and algae bloom at a fully operational mode. These monitoring systems differ from the existing ones by the analysis of a wide spectrum of satellite, meteorological and oceanographic data, as well as by a numerical modeling of oil spill transformation and transport in real weather conditions. Our experience in the Baltic Sea includes: (1 integrated satellite monitoring of oil production at the LUKOIL-KMN Ltd. D-6 oil rig in the Southeastern Baltic Sea (Kravtsovskoe oil field in 2004-2014; (2 integrated satellite monitoring of the “Nord Stream” underwater gas pipeline construction and exploitation in the Gulf of Finland (2010-2013; (3 numerical modeling of risks of oil pollution caused by shipping along the main maritime shipping routes in the Gulf of Finland, the Baltic Proper, and in the Southeastern Baltic Sea; (4 numerical modeling of risks of oil pollution caused by oil production at D-6 oil rig and oil transportation on shore via the connecting underwater oil pipeline.

  1. Direct assimilation of satellite radiance data in GRAPES variational assimilation system

    Institute of Scientific and Technical Information of China (English)

    ZHU GuoFu; XUE JiShan; ZHANG Hua; LIU ZhiQuan; ZHUANG ShiYu; HUANG LiPing; DONG PeiMing

    2008-01-01

    Variational method is capable of dealing with observations that have a complicated nonlinear relation with model variables representative of the atmospheric state, and so make it possible to directly as-similate such measured variables as satellite radiance, which have a nonlinear relation with the model variables. Assimilation of any type of observations requires a corresponding observation operator, which establishes a specific mapping from the space of the model state to the space of observation. This paper presents in detail how the direct assimilation of real satellite radiance data is implemented in the GRAPES-3DVar analysis system. It focuses on all the components of the observation operator for direct assimilation of real satellite radiance data, including a spatial interpolation operator that trans-forms variables from model grid points to observation locations, a physical transformation from model variables to observed elements with different choices of model variables, and a data quality control. Assimilation experiments, using satellite radiances such as NOAA17 AMSU-A and AMSU-B (Advanced Microwave Sounding Unit), are carried out with two different schemes. The results from these experi-ments can be physically understood and clearly reflect a rational effect of direct assimilation of satellite radiance data in GRAPES-3DVar analysis system.

  2. The Multi-Sensor Aerosol Products Sampling System (MAPSS) for Integrated Analysis of Satellite Retrieval Uncertainties

    Science.gov (United States)

    Ichoku, Charles; Petrenko, Maksym; Leptoukh, Gregory

    2010-01-01

    Among the known atmospheric constituents, aerosols represent the greatest uncertainty in climate research. Although satellite-based aerosol retrieval has practically become routine, especially during the last decade, there is often disagreement between similar aerosol parameters retrieved from different sensors, leaving users confused as to which sensors to trust for answering important science questions about the distribution, properties, and impacts of aerosols. As long as there is no consensus and the inconsistencies are not well characterized and understood ', there will be no way of developing reliable climate data records from satellite aerosol measurements. Fortunately, the most globally representative well-calibrated ground-based aerosol measurements corresponding to the satellite-retrieved products are available from the Aerosol Robotic Network (AERONET). To adequately utilize the advantages offered by this vital resource,., an online Multi-sensor Aerosol Products Sampling System (MAPSS) was recently developed. The aim of MAPSS is to facilitate detailed comparative analysis of satellite aerosol measurements from different sensors (Terra-MODIS, Aqua-MODIS, Terra-MISR, Aura-OMI, Parasol-POLDER, and Calipso-CALIOP) based on the collocation of these data products over AERONET stations. In this presentation, we will describe the strategy of the MAPSS system, its potential advantages for the aerosol community, and the preliminary results of an integrated comparative uncertainty analysis of aerosol products from multiple satellite sensors.

  3. Assessing the Potential Use of Eye-Tracking Triangulation for Evaluating the Usability of an Online Diabetes Exercise System.

    Science.gov (United States)

    Schaarup, Clara; Hartvigsen, Gunnar; Larsen, Lars Bo; Tan, Zheng-Hua; Årsand, Eirik; Hejlesen, Ole Kristian

    2015-01-01

    The Online Diabetes Exercise System was developed to motivate people with Type 2 diabetes to do a 25 minutes low-volume high-intensity interval training program. In a previous multi-method evaluation of the system, several usability issues were identified and corrected. Despite the thorough testing, it was unclear whether all usability problems had been identified using the multi-method evaluation. Our hypothesis was that adding the eye-tracking triangulation to the multi-method evaluation would increase the accuracy and completeness when testing the usability of the system. The study design was an Eye-tracking Triangulation; conventional eye-tracking with predefined tasks followed by The Post-Experience Eye-Tracked Protocol (PEEP). Six Areas of Interests were the basis for the PEEP-session. The eye-tracking triangulation gave objective and subjective results, which are believed to be highly relevant for designing, implementing, evaluating and optimizing systems in the field of health informatics. Future work should include testing the method on a larger and more representative group of users and apply the method on different system types.

  4. Acceptance Testing of a Satellite SCADA Photovoltaic-Diesel Hybrid System

    Science.gov (United States)

    Kalu, A.; Emrich, C.; Ventre, G.; Wilson, W.; Acosta, Roberto (Technical Monitor)

    2000-01-01

    Satellite Supervisory Control and Data Acquisition (SCADA) of a Photovoltaic (PV)/diesel hybrid system was tested using NASA's Advanced Communication Technology Satellite (ACTS) and Ultra Small Aperture Terminal (USAT) ground stations. The setup consisted of a custom-designed PV/diesel hybrid system, located at the Florida Solar Energy Center (FSEC), which was controlled and monitored at a "remote" hub via Ka-band satellite link connecting two 1/4 Watt USATs in a SCADA arrangement. The robustness of the communications link was tested for remote monitoring of the health and performance of a PV/diesel hybrid system, and for investigating load control and battery charging strategies to maximize battery capacity and lifetime, and minimize loss of critical load probability. Baseline hardware performance test results demonstrated that continuous two-second data transfers can be accomplished under clear sky conditions with an error rate of less than 1%. The delay introduced by the satellite (1/4 sec) was transparent to synchronization of satellite modem as well as to the PV/diesel-hybrid computer. End-to-end communications link recovery times were less than 36 seconds for loss of power and less than one second for loss of link. The system recovered by resuming operation without any manual intervention, which is important since the 4 dB margin is not sufficient to prevent loss of the satellite link during moderate to heavy rain. Hybrid operations during loss of communications link continued seamlessly but real-time monitoring was interrupted. For this sub-tropical region, the estimated amount of time that the signal fade will exceed the 4 dB margin is about 10%. These results suggest that data rates of 4800 bps and a link margin of 4 dB with a 1/4 Watt transmitter are sufficient for end-to-end operation in this SCADA application.

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

    Science.gov (United States)

    Naderi, F. (Editor)

    1982-01-01

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

  6. Global Navigation Satellite System Multipath Mitigation Using a Wave-Absorbing Shield.

    Science.gov (United States)

    Yang, Haiyan; Yang, Xuhai; Sun, Baoqi; Su, Hang

    2016-08-22

    Code multipath is an unmanaged error source in precise global navigation satellite system (GNSS) observation processing that limits GNSS positioning accuracy. A new technique for mitigating multipath by installing a wave-absorbing shield is presented in this paper. The wave-absorbing shield was designed according to a GNSS requirement of received signals and collected measurements to achieve good performance. The wave-absorbing shield was installed at the KUN1 and SHA1 sites of the international GNSS Monitoring and Assessment System (iGMAS). Code and carrier phase measurements of three constellations were collected on the dates of the respective installations plus and minus one week. Experiments were performed in which the multipath of the measurements obtained at different elevations was mitigated to different extents after applying the wave-absorbing shield. The results of an analysis and comparison show that the multipath was mitigated by approximately 17%-36% on all available frequencies of BeiDou Navigation Satellite System (BDS), Global Positioning System (GPS), and Global Navigation Satellite System (GLONASS) satellites. The three-dimensional accuracies of BDS, GPS, and GLONASS single-point positioning (SPP) were, respectively, improved by 1.07, 0.63 and 0.49 m for the KUN1 site, and by 0.72, 0.79 and 0.73 m for the SHA1 site. Results indicate that the multipath of the original observations was mitigated by using the wave-absorbing shield.

  7. EYE GAZE TRACKING

    DEFF Research Database (Denmark)

    2017-01-01

    This invention relates to a method of performing eye gaze tracking of at least one eye of a user, by determining the position of the center of the eye, said method comprising the steps of: detecting the position of at least three reflections on said eye, transforming said positions to spanning...... a normalized coordinate system spanning a frame of reference, wherein said transformation is performed based on a bilinear transformation or a non linear transformation e.g. a möbius transformation or a homographic transformation, detecting the position of said center of the eye relative to the position...... of said reflections and transforming this position to said normalized coordinate system, tracking the eye gaze by tracking the movement of said eye in said normalized coordinate system. Thereby calibration of a camera, such as knowledge of the exact position and zoom level of the camera, is avoided...

  8. Minimization of influence by the drooping eyelid in extracting pupil center tor eye tracking systems

    Institute of Scientific and Technical Information of China (English)

    Xiaopeng Wei; Dongsheng Zhou; Qiang Zhang; Boxiang Xiao

    2008-01-01

    Precise pupil center detection is an important factor for gaze tracking in video-oculography(VOG)systems.Existing methods per-form well to extract the features when the area of pupil in eye image is clear,whereas,interferences,such as eyelashes,corneal reflection etc.,will lead to a low SUCCESS rate.One main reason is the closure of eyelids.In this paper,a systemic 3D transformation algorithm is proposed to accurately ascertain the pupil center,in spite of the complicating factors mentioned above.Experiments show the good per-formance of our method.And the pupil center could be extracted accurately,even though only 25%of the pupil is visible.

  9. A free geometry model-independent neural eye-gaze tracking system

    Directory of Open Access Journals (Sweden)

    Gneo Massimo

    2012-11-01

    Full Text Available Abstract Background Eye Gaze Tracking Systems (EGTSs estimate the Point Of Gaze (POG of a user. In diagnostic applications EGTSs are used to study oculomotor characteristics and abnormalities, whereas in interactive applications EGTSs are proposed as input devices for human computer interfaces (HCI, e.g. to move a cursor on the screen when mouse control is not possible, such as in the case of assistive devices for people suffering from locked-in syndrome. If the user’s head remains still and the cornea rotates around its fixed centre, the pupil follows the eye in the images captured from one or more cameras, whereas the outer corneal reflection generated by an IR light source, i.e. glint, can be assumed as a fixed reference point. According to the so-called pupil centre corneal reflection method (PCCR, the POG can be thus estimated from the pupil-glint vector. Methods A new model-independent EGTS based on the PCCR is proposed. The mapping function based on artificial neural networks allows to avoid any specific model assumption and approximation either for the user’s eye physiology or for the system initial setup admitting a free geometry positioning for the user and the system components. The robustness of the proposed EGTS is proven by assessing its accuracy when tested on real data coming from: i different healthy users; ii different geometric settings of the camera and the light sources; iii different protocols based on the observation of points on a calibration grid and halfway points of a test grid. Results The achieved accuracy is approximately 0.49°, 0.41°, and 0.62° for respectively the horizontal, vertical and radial error of the POG. Conclusions The results prove the validity of the proposed approach as the proposed system performs better than EGTSs designed for HCI which, even if equipped with superior hardware, show accuracy values in the range 0.6°-1°.

  10. Repeatability Evaluation of a Contrast Sensitivity System for Transfer to the Eye Clinic

    Science.gov (United States)

    Alcalde, N. G.; Castillo, L. R.; Filgueira, C. Paz; Colombo, E. M.

    2016-04-01

    The Contrast Sensitivity Function (CSF) is a valuable tool which can be used to characterize functional vision and also for the diagnosis and management of patients with different eye diseases. In spite of its usefulness, the CSF is currently hardly ever used in clinical practice. The aim of this study was to validate the use of the system called FVC-100 (Tecnovinc-UNT-CONICET, Argentina), which calculates the CSF, in order to transfer this important tool to ophthalmological clinics. The validation was carried out through the design of a repeatability test and the subsequent analysis of the results. Furthermore, we evaluated the impact of different factors influencing the repeatability of the measurements such as age and previous training. The tests were based on the discrimination of sinusoidal gratings for different spatial frequencies (1, 4 and 12 c/°) in both eyes of 12 people, aged between 20 and 70. The results show that the calculated values of SC of each subject have a high repeatability and are not dependent on age or training. These results allow us to conclude positively regarding the effectiveness of the FVC-100, and to validate its use in clinics for the calculation of the FSC as a standard measure of functional vision quality.

  11. Delay analysis of a satellite channel reservation system with variable frame format

    Science.gov (United States)

    Mine, H.; Ohno, K.; Shioyama, T.

    1983-06-01

    In describing the operation, it is pointed out that the current queue length at each user is reported through minislots in the up-link header to a satellite possessing processing capability. The satellite broadcasts slot assignments for transmission in the next frame to users through the down-link header on the basis of the users' reported queue status. The number of data slots per frame varies according to the reported queue status of the users. A Markov-chain model is presented for analyzing the average total delay of the system. Numerical results are given for comparing the delay of the system with the delay of TDMA and reservation systems with fixed frame format. The system is shown to provide a better delay/throughput performance than these other systems over a wide range of traffic intensities. In addition, the delay curve of the system is relatively flat up to a traffic intensity of approximately 0.8.

  12. Satellite constellation design with genetic algorithms based on system performance

    Institute of Scientific and Technical Information of China (English)

    Xueying Wang; Jun Li; Tiebing Wang; Wei An; Weidong Sheng

    2016-01-01

    Satelite constelation design for space optical sys-tems is essentialy a multiple-objective optimization problem. In this work, to tackle this chalenge, we first categorize the performance metrics of the space optical system by taking into account the system tasks (i.e., target detection and tracking). We then propose a new non-dominated sorting genetic algo-rithm (NSGA) to maximize the system surveilance perfor- mance. Pareto optimal sets are employed to deal with the conflicts due to the presence of multiple cost functions. Simulation results verify the validity and the improved per-formance of the proposed technique over benchmark meth-ods.

  13. Development of a Nitrous Oxide-Based Monopropellant Propulsion System for Small Satellites

    OpenAIRE

    Tarantini, Vincent; Risi, Ben; Orr, Nathan

    2016-01-01

    As the demand for highly capable microsatellite missions continues to grow, so too does the need for small yet effective satellite technologies. One area which needs to be addressed is compact propulsion systems capable of performing on-orbit maneuvers, station keeping, and de-orbit impulses with good efficiency. Another important consideration for propulsion systems is the safety and ease in handling, integrating, and testing the propulsion system. This is particularly important for small sa...

  14. Eye Injuries

    Science.gov (United States)

    The structure of your face helps protect your eyes from injury. Still, injuries can damage your eye, sometimes severely enough that you could lose your vision. Most eye injuries are preventable. If you play sports or ...

  15. Eye Wear

    Science.gov (United States)

    Eye wear protects or corrects your vision. Examples are Sunglasses Safety goggles Glasses (also called eyeglasses) Contact ... jobs and some sports carry a risk of eye injury. Thousands of children and adults get eye ...

  16. Eye Cancer

    Science.gov (United States)

    Cancer of the eye is uncommon. It can affect the outer parts of the eye, such as the eyelid, which are made up ... adults are melanoma and lymphoma. The most common eye cancer in children is retinoblastoma, which starts in ...

  17. Eye Diseases

    Science.gov (United States)

    ... the back of the eye Macular degeneration - a disease that destroys sharp, central vision Diabetic eye problems ... defense is to have regular checkups, because eye diseases do not always have symptoms. Early detection and ...

  18. Radiation budget and related measurements in 1985 and beyond. [earth radiation budget satellite system

    Science.gov (United States)

    1978-01-01

    Development of systems for obtaining radiation budget and cloud data is discussed. Instruments for measuring total solar irradiance, total infrared flux, reflected solar flux, and cloud heights and properties are considered. Other topics discussed include sampling by multiple satellites, user identification, and determination of the parameters that need to be measured.

  19. The method of the antenna system positioning for satellite communication network radiomonitoring complex

    OpenAIRE

    Гребенюк, Олег Петрович

    2014-01-01

    The method of orientation of the antenna system of complex of radiomonitoring of satellite communication networks is offered. A method takes into account the features of construction and functional setting of a transport stream of standard of DVB ‑ S.

  20. MISAT : Designing a Series of Powerful Small Satellites Based upon Micro Systems Technology

    NARCIS (Netherlands)

    Gill, E.; Monna, G.L.E.; Scherpen, J.M.A.; Verhoeven, C.J.M.

    2007-01-01

    MISAT is a research and development cluster which will create a small satellite platform based on Micro Systems Technology (MST) aiming at innovative space as well as terrestrial applications. MISAT is part of the Dutch MicroNed program which has established a microsystems infrastructure to fully

  1. Study on networking issues of medium earth orbit satellite communications systems

    Science.gov (United States)

    Araki, Noriyuki; Shinonaga, Hideyuki; Ito, Yasuhiko

    1993-01-01

    Two networking issues of communications systems with medium earth orbit (MEO) satellites, namely network architectures and location determination and registration methods for hand-held terminals, are investigated in this paper. For network architecture, five candidate architectures are considered and evaluated in terms of signaling traffic. For location determination and registration, two methods are discussed and evaluated.

  2. Modeling radiation conditions in orbits of projected system of small satellites for radiation monitoring

    Science.gov (United States)

    Panasyuk, M. I.; Podzolko, M. V.; Kovtyukh, A. S.; Osedlo, V. I.; Tulupov, V. I.; Yashin, I. V.

    2016-11-01

    Calculated estimates are presented for the accumulated radiation doses behind the shields of various thicknesses in the orbits of projected at Skobeltsyn Institute of Nuclear Physics, Moscow State University system of small satellites for radiation monitoring. The results are analyzed and compared with the calculation data for other actively exploited near-Earth orbits.

  3. Discovery of a New AM CVn System with the Kepler Satellite

    DEFF Research Database (Denmark)

    Fontaine, G.; Brassard, P.; Green, Elizabeth M.;

    2011-01-01

    We report the discovery of a new AM CVn system on the basis of broadband photometry obtained with the Kepler satellite supplemented by ground-based optical spectroscopy. Initially retained on Kepler target lists as a potential compact pulsator, the blue object SDSS J190817.07+394036.4 (KIC...

  4. MISAT : Designing a Series of Powerful Small Satellites Based upon Micro Systems Technology

    NARCIS (Netherlands)

    Gill, E.; Monna, G.L.E.; Scherpen, J.M.A.; Verhoeven, C.J.M.

    2007-01-01

    MISAT is a research and development cluster which will create a small satellite platform based on Micro Systems Technology (MST) aiming at innovative space as well as terrestrial applications. MISAT is part of the Dutch MicroNed program which has established a microsystems infrastructure to fully ex

  5. Next-generation satellite gravimetry for measuring mass transport in the Earth system

    NARCIS (Netherlands)

    Teixeira Encarnação, J.

    2015-01-01

    The main objective of the thesis is to identify the optimal set-up for future satellite gravimetry missions aimed at monitoring mass transport in the Earth’s system.The recent variability of climatic patterns, the spread of arid regions and associ- ated changes in the hydrological cycle, and vigorou

  6. Error analysis for relay type satellite-aided search and rescue systems

    Science.gov (United States)

    Marini, J. W.

    1979-01-01

    An analysis is made of the errors in the determination of the position of an emergency transmitter in a satellite-aided search and rescue system. The satellite is assumed to be at a height of 820 km in a near-circular near polar orbit. Short data spans of four minutes or less are used. The error sources considered are measurement noise, transmitter frequency drift, ionospheric effects, and error in the assumed height of the transmitter. The errors are calculated for several different transmitter positions, data rates, and data spans. The only transmitter frequency used was 406 MHz, but the result can be scaled to different frequencies.

  7. An Overview of the Joint Polar Satellite System (JPSS Science Data Product Calibration and Validation

    Directory of Open Access Journals (Sweden)

    Lihang Zhou

    2016-02-01

    Full Text Available The Joint Polar Satellite System (JPSS will launch its first JPSS-1 satellite in early 2017. The JPSS-1 and follow-on satellites will carry aboard an array of instruments including the Visible Infrared Imaging Radiometer Suite (VIIRS, the Cross-track Infrared Sounder (CrIS, the Advanced Technology Microwave Sounder (ATMS, and the Ozone Mapping and Profiler Suite (OMPS. These instruments are similar to the instruments currently operating on the Suomi National Polar-orbiting Partnership (S-NPP satellite. In preparation for the JPSS-1 launch, the JPSS program at the Center for Satellite Applications and Research (JSTAR Calibration/Validation (Cal/Val teams, have laid out the Cal/Val plans to oversee JPSS-1 science products’ algorithm development efforts, verification and characterization of these algorithms during the pre-launch period, calibration and validation of the products during post-launch, and long-term science maintenance (LTSM. In addition, the team has developed the necessary schedules, deliverables and infrastructure for routing JPSS-1 science product algorithms for operational implementation. This paper presents an overview of these efforts. In addition, this paper will provide insight into the processes of both adapting S-NPP science products for JPSS-1 and performing upgrades for enterprise solutions, and will discuss Cal/Val processes and quality assurance procedures.

  8. Innovative use of global navigation satellite systems for flight inspection

    Science.gov (United States)

    Kim, Eui-Ho

    The International Civil Aviation Organization (ICAO) mandates flight inspection in every country to provide safety during flight operations. Among many criteria of flight inspection, airborne inspection of Instrument Landing Systems (ILS) is very important because the ILS is the primary landing guidance system worldwide. During flight inspection of the ILS, accuracy in ILS landing guidance is checked by using a Flight Inspection System (FIS). Therefore, a flight inspection system must have high accuracy in its positioning capability to detect any deviation so that accurate guidance of the ILS can be maintained. Currently, there are two Automated Flight Inspection Systems (AFIS). One is called Inertial-based AFIS, and the other one is called Differential GPS-based (DGPS-based) AFIS. The Inertial-based AFIS enables efficient flight inspection procedures, but its drawback is high cost because it requires a navigation-grade Inertial Navigation System (INS). On the other hand, the DGPS-based AFIS has relatively low cost, but flight inspection procedures require landing and setting up a reference receiver. Most countries use either one of the systems based on their own preferences. There are around 1200 ILS in the U.S., and each ILS must be inspected every 6 to 9 months. Therefore, it is important to manage the airborne inspection of the ILS in a very efficient manner. For this reason, the Federal Aviation Administration (FAA) mainly uses the Inertial-based AFIS, which has better efficiency than the DGPS-based AFIS in spite of its high cost. Obviously, the FAA spends tremendous resources on flight inspection. This thesis investigates the value of GPS and the FAA's augmentation to GPS for civil aviation called the Wide Area Augmentation System (or WAAS) for flight inspection. Because standard GPS or WAAS position outputs cannot meet the required accuracy for flight inspection, in this thesis, various algorithms are developed to improve the positioning ability of Flight

  9. Evaluating the Cloud Cover Forecast of NCEP Global Forecast System with Satellite Observation

    CERN Document Server

    Ye, Quanzhi

    2011-01-01

    To assess the quality of daily cloud cover forecast generated by the operational global numeric model, the NCEP Global Forecast System (GFS), we compose a large sample with outputs from GFS model and satellite observations from the International Satellite Cloud Climatology Project (ISCCP) in the period of July 2004 to June 2008, to conduct a quantitative and systematic assessment of the performance of a cloud model that covers a relatively long range of time, basic cloud types, and in a global view. The evaluation has revealed the goodness of the model forecast, which further illustrates our completeness on understanding cloud generation mechanism. To quantity the result, we found a remarkably high correlation between the model forecasts and the satellite observations over the entire globe, with mean forecast error less than 15% in most areas. Considering a forecast within 30% difference to the observation to be a "good" one, we find that the probability for the GFS model to make good forecasts varies between...

  10. Infrared Eye: Prototype 2

    Science.gov (United States)

    2016-06-07

    within the wide field and slaved to the operator’s line of sight by means of an eye- tracking system. The images from both cameras are fused and shown...simultaneously on a high resolution CRT display unit, interfaced with the eye- tracking unit in order to optimize the human-machine interface. The IR Eye...system was flight tested using the Advanced system Research Aircraft (Bell 412 helicopter) from the Flight Research Laboratory of the National Research

  11. Telecommunication service markets through the year 2000 in relation to millimeter wave satellite systems

    Science.gov (United States)

    Stevenson, S. M.

    1979-01-01

    NASA is currently conducting a series of millimeter wave satellite system and market studies to develop 30/20 GHz satellite system concepts that have commercial potential for the period 1980-2000. The results of the market studies to-date focusing on the overall demand forecasts and distributions by geographic location, distance, and user category are discussed. Tables are presented indicating baseline market forecast voice and video services, data service category, impacted baseline forecast, and traffic/distance distribution voice services. It is concluded that the total market and system activity will be influential in determining the potential role of millimeter wave systems in the overall transmission needs of the nation, and the amount of the total forecasted traffic suitable for millimeter wave systems.

  12. Networks systems and operations. [wideband communication techniques for data links with satellites

    Science.gov (United States)

    1975-01-01

    The application of wideband communication techniques for data links with satellites is discussed. A diagram of the demand assigned voice communications system is provided. The development of prototype integrated spacecraft paramps at S- and C-bands is described and the performance of space-qualified paramps is tabulated. The characteristics of a dual parabolic cylinder monopulse zoom antenna for use with the tracking and data relay satellite system (TDRSS) are analyzed. The development of a universally applicable transponder at S-band is reported. A block diagram of the major subassemblies of the S-band transponder is included. The technology aspects of network timing and synchronization of communication systems are to show the use of the Omega navigation system. The telemetry data compression system used during the Skylab program is evaluated.

  13. The Design and Implementation of a Remote Fault Reasoning Diagnosis System for Meteorological Satellites Data Acquisition

    Directory of Open Access Journals (Sweden)

    Zhu Jie

    2017-01-01

    Full Text Available Under the background of the trouble shooting requirements of FENGYUN-3 (FY-3 meteorological satellites data acquisition in domestic and oversea ground stations, a remote fault reasoning diagnosis system is developed by Java 1.6 in eclipse 3.6 platform. The general framework is analyzed, the workflow is introduced. Based on the system, it can realize the remote and centralized monitoring of equipment running status in ground stations,triggering automatic fault diagnosis and rule based fault reasoning by parsing the equipment quality logs, generating trouble tickets and importing expert experience database, providing text and graphics query methods. Through the practical verification, the system can assist knowledge engineers in remote precise and rapid fault location with friendly graphical user interface, boost the fault diagnosis efficiency, enhance the remote monitoring ability of integrity operating control system. The system has a certain practical significance to improve reliability of FY-3 meteorological satellites data acquisition.

  14. Circumventing 'free care' and 'shouting louder': using a health systems approach to study eye health system sustainability in government and mission facilities of north-west Tanzania.

    Science.gov (United States)

    Palmer, Jennifer J; Gilbert, Alice; Choy, Michelle; Blanchet, Karl

    2016-09-09

    Little is known about the contributions of faith-based organisations (FBOs) to health systems in Africa. In the specialist area of eye health, international and domestic Christian FBOs have been important contributors as service providers and donors, but they are also commonly critiqued as having developed eye health systems parallel to government structures which are unsustainable. In this study, we use a health systems approach (quarterly interviews, a participatory sustainability analysis exercise and a social network analysis) to describe the strategies used by eye care practitioners in four hospitals of north-west Tanzania to navigate the government, church mission and donor rules that govern eye services delivery there. Practitioners in this region felt eye care was systemically neglected by government and therefore was 'all under the NGOs', but support from international donors was also precarious. Practitioners therefore adopted four main strategies to improve the sustainability of their services: (1) maintain 'sustainability funds' to retain financial autonomy over income; (2) avoid granting government user fee exemptions to elderly patients who are the majority of service users; (3) expand or contract outreach services as financial circumstances change; and (4) access peer support for problem-solving and advocacy. Mission-based eye teams had greater freedom to increase their income from user fees by not implementing government policies for 'free care'. Teams in all hospitals, however, found similar strategies to manage their programmes even when their management structures were unique, suggesting the importance of informal rules shared through a peer network in governing eye care in this pluralistic health system. Health systems research can generate new evidence on the social dynamics that cross public and private sectors within a local health system. In this area of Tanzania, Christian FBOs' investments are important, not only in terms of the population

  15. Comparison of a remote operating slit-lamp microscope system with a conventional slit-lamp microscope system for examination of trabeculectomy eyes.

    Science.gov (United States)

    Kashiwagi, Kenji; Tanabe, Naohiko; Go, Kentaro; Imasawa, Mitsuhiro; Mabuchi, Fumihiko; Chiba, Tetsuya; Sugiyama, Atsushi; Abe, Keitetsu

    2013-01-01

    To compare 2-dimensional (2D) photo imaging with slit-lamp photo imaging for examination of trabeculectomy eyes, and to compare the accuracy and consistency of examination of trabeculectomy eyes with a remote operating slit-lamp microscope system (referred to as "remote slit lamp" hereafter) and a conventional slit-lamp microscope system (referred to as "slit lamp" hereafter). Thirty-five eyes of 35 patients having a history of trabeculectomy were enrolled in the study that compared 2D photo imaging with slit-lamp photo imaging for the evaluation of trabeculectomy eyes. Five ophthalmologists evaluated the 2D images and the slit-lamp images independently with masking of patient information. Evaluation scores were compared with those provided by a glaucoma specialist using the slit lamp as standard. Fifteen eyes from 15 patients having a history of trabeculectomy were enrolled in the study that investigated the accuracy and consistency of examination of trabeculectomy eyes with a remote slit lamp and a slit lamp. Central anterior chamber depth, bleb height, and bleb extent evaluated by the slit-lamp photo imaging showed significantly higher consistency with the standard than those evaluated by 2D photo imaging (Psystem shows similar potential to the slit-lamp system for the evaluation of trabeculectomy eyes, although the evaluation time is much longer.

  16. Grand Challenges in Space Technology: Distributed Satellite Systems

    Science.gov (United States)

    2001-07-01

    modem interests in readability, extensibility and expressiveness. To achieve these goals Embedded C ++ (EC++) has been chosen as the standard for GRRDE...of embedded C ++ as a programming language for FSW. The ongoing simulation of the TechSat21 system will provide an invaluable analysis of this mission...time. The study has also demonstrated the suitability of OSE as a real-time distributed operating system and of embedded C ++ as a programming language

  17. 78 FR 21629 - Certain Two-Way Global Satellite Communication Devices, System and Components Thereof Issuance of...

    Science.gov (United States)

    2013-04-11

    ... COMMISSION Certain Two-Way Global Satellite Communication Devices, System and Components Thereof Issuance of... importation, and the sale within the United States after importation of certain two-way global satellite communication devices, system and components thereof by reason of infringement of certain claims of U.S. Patent...

  18. Wildland fire management. Volume 2: Wildland fire control 1985-1995. [satellite information system for California fire problems

    Science.gov (United States)

    Saveker, D. R. (Editor)

    1973-01-01

    The preliminary design of a satellite plus computer earth resources information system is proposed for potential uses in fire prevention and control in the wildland fire community. Suggested are satellite characteristics, sensor characteristics, discrimination algorithms, data communication techniques, data processing requirements, display characteristics, and costs in achieving the integrated wildland fire information system.

  19. Satellite laser ranging measurements in South Africa: Contributions to earth system sciences

    Directory of Open Access Journals (Sweden)

    Christina M. Botai

    2015-03-01

    Full Text Available This contribution reassesses progress in the development of satellite laser ranging (SLR technology and its scientific and societal applications in South Africa. We first highlight the current global SLR tracking stations within the framework of the International Laser Ranging Service (ILRS and the artificial satellites currently being tracked by these stations. In particular, the present work focuses on analysing SLR measurements at Hartebeesthoek Radio Astronomy Observatory (HartRAO, South Africa, based on the MOBLAS-6 SLR configuration. Generally, there is a weak geometry of ILRS stations in the southern hemisphere and the SLR tracking station at HartRAO is the only active ILRS station operating on the African continent. The SLR-derived products such as station positions and velocities, satellite orbits, components of earth's gravity field and their temporal variations, earth orientation parameters are collected, merged, achieved and distributed by the ILRS under the Crustal Dynamic Data Information System. These products are used in various research fields such as detection and monitoring of tectonic plate motion, crustal deformation, earth rotation, polar motion, and the establishment and monitoring of International Terrestrial Reference Frames, as well as modelling of the spatio-temporal variations of the earth's gravity field. The MOBLAS-6 tracking station is collocated with other geodetic techniques such as very long baseline interferometry and Global Navigation Satellite Systems, thus making this observatory a fiducial geodetic location. Some applications of the SLR data products are described within the context of earth system science.

  20. Environmental assessment for the satellite power system concept development and evaluation program: atmospheric effects

    Energy Technology Data Exchange (ETDEWEB)

    Rote, D.M.; Brubaker, K.L.; Lee, J.L.

    1980-11-01

    The US Department of Energy (DOE) has undertaken a preliminary, three-year program to investigate the impacts of the construction and operation of a satellite power system, of unprecedented scale. The Department of Energy's program, titled The Concept Development and Evaluation Program, focused its investigations on a Reference System description that calls for the use of either silicon (Si) or gallium aluminum-arsenide (GaAlAs) photovoltaic cells on 60 satellites to be constructed in GEO over a 30-yr period. Rectennas would be constructed on the ground to receive microwave energy from the satellites. Each satellite-rectenna pair is designed to produce 5 GW of power on an essentially continuous basis for use as a baseload power source for an electric power distribution system. The environmental assessment part of the program was divided into five interdependent task areas. The present document constitutes the final technical report on one of the five task areas, the Assessment of the Atmospheric Effects, and as such presents an in-depth summary of work performed during the assessment program. The issues associated with SPS activities in the troposphere are examined. These include tropospheric weather modification related to rectenna operations and rocket launches, and air quality impacts related to rocketlaunch ground clouds. Then progressing upward through the various levels of the atmosphere, the principal middle and upper atmospheric effects associated with rocket effluents are analyzed. Finally, all of the potential SPS atmospheric effects are summarized.