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Time for GIOVE-A: the onboard rubidium clock experiment / J. Hahn in GPS world, vol 18 n° 5 (May 2007)
[article]
Titre : Time for GIOVE-A: the onboard rubidium clock experiment Type de document : Article/Communication Auteurs : J. Hahn, Auteur ; D. Navarro-Reyes, Auteur ; F. Gonzalez, Auteur ; et al., Auteur Année de publication : 2007 Article en page(s) : pp 64 - 69 Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Satellites artificiels
[Termes IGN] GIOVE (satellite)
[Termes IGN] horloge atomique
[Termes IGN] temps universel
[Termes IGN] test de performanceRésumé : (Editeur) Apart from the ability to launch satellites, what was the single greatest technological development which has made global navigation satellite systems possible? Time's up (that should give you a hint). It is the atomic clock. GNSS receivers work by accurately timing how long it takes signals to travel from the satellites' antennas to the receiver's antenna and converting the time delays to ranges using the speed of light. Each delay is essentially the difference between the time a particular signal transition was received, as measured with the receiver's clock, and the time that same transition left a satellite, as measured with the satellite's clock. The delays must be measured very accurately since a timing error of just 10 nanoseconds is equivalent to a ranging error of about 3 meters. One of the clocks must be a highly stable reference clock. The demands on the timekeeping ability of the other clock is much less since its timing error can be estimated from measurements. The only practical approach for a GNSS is to place reference clocks in the satellites, permitting receivers to operate with a low-cost clock whose error is estimated along with the receiver's coordinates from the simultaneous measurements made on four or more satellites. Only atomic clocks have the required accuracy and stability to be used as reference clocks. Scientists have developed three basic kinds of atomic clock, each based on a different element ; cesium, rubidium, and hydrogen. The GPS Block II and IIA satellites each carried four clocks: two cesium and two rubidium whereas the Block IIR and IIR-M satellites each carry three rubidium clocks. GLONASS satellites carry three cesium clocks. The European Galileo system will also use redundant atomic clocks onboard its satellites. One candidate clock for the future Galileo satellites is the European Rubidium Atomic Frequency Standard. Two of these clocks are flying onboard the GIOVE-A test satellite which was launched on December 28, 2005. In this month's column, the GIOVE clock experiment team discusses the tests which have been conducted to assess the performance of the satellite's active clock and their future plans for onboard clock assessment including the passive hydrogen maser to be flown on GIOVE-B. Copyright Questex Media Group Inc Numéro de notice : A2007-223 Affiliation des auteurs : non IGN Thématique : IMAGERIE/POSITIONNEMENT Nature : Article DOI : sans Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=28586
in GPS world > vol 18 n° 5 (May 2007) . - pp 64 - 69[article]Réservation
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Code-barres Cote Support Localisation Section Disponibilité 067-07051 RAB Revue Centre de documentation En réserve L003 Disponible GNSS : Update, Giove-B Bom Bursts / Huibert-Jan Lekkerkerk in Geoinformatics, vol 10 n° 3 (01/04/2007)
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Titre : GNSS : Update, Giove-B Bom Bursts Type de document : Article/Communication Auteurs : Huibert-Jan Lekkerkerk, Auteur Année de publication : 2007 Article en page(s) : pp 22 - 23 Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Satellites artificiels
[Termes IGN] constellation Galileo
[Termes IGN] GIOVE (satellite)
[Termes IGN] Global Navigation Satellite SystemRésumé : (Auteur) The ESA is fed up with the delays surrounding the Galileo program in general and GIOVE-B in particular and has commissioned Surrey Technologies to build GIOVE-A2. Without an active satellite, Galileo stands the risk of losing its frequency licenses. Moreover, it is still unclear whether the last Beidou launch was successful or not. Glonass, however, is investigating the use of GPS / Galileo-like transmission techniques. Copyright GeoInformatics Numéro de notice : A2007-195 Affiliation des auteurs : non IGN Thématique : IMAGERIE/POSITIONNEMENT Nature : Article DOI : sans Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=28558
in Geoinformatics > vol 10 n° 3 (01/04/2007) . - pp 22 - 23[article]Modelling and prediction of GPS availability with digital photogrammetry and LiDAR / Georges E. Taylor in International journal of geographical information science IJGIS, vol 21 n° 1-2 (january 2007)
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Titre : Modelling and prediction of GPS availability with digital photogrammetry and LiDAR Type de document : Article/Communication Auteurs : Georges E. Taylor, Auteur ; J. Li, Auteur ; et al., Auteur Année de publication : 2007 Article en page(s) : pp 1 - 20 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Applications photogrammétriques
[Termes IGN] application informatique
[Termes IGN] constellation GPS
[Termes IGN] données lidar
[Termes IGN] modèle numérique de terrain
[Termes IGN] photogrammétrie numérique
[Termes IGN] positionnement cinématique en temps réel
[Termes IGN] récepteur GPS
[Termes IGN] satellite GPS
[Termes IGN] système d'information géographique
[Termes IGN] temps réel
[Termes IGN] visibilitéRésumé : (Auteur) This paper describes an automated method for predicting the number of satellites visible to a GPS receiver, at any point on the Earth's surface at any time. Intervisibility analysis between a GPS receiver and each potentially visible GPS satellite is performed using a number of different surface models and satellite orbit calculations. The developed software can work with various ephemeris data, and will compute satellite visibility in real time. Real-time satellite availability prediction is very useful for mobile applications such as in-car navigation systems, personal navigations systems and LBS. The implementation of the method is described and the results are reported. Copyright Taylor & Francis Numéro de notice : A2007-023 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Article DOI : 10.1080/13658810600816540 En ligne : https://doi.org/10.1080/13658810600816540 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=28389
in International journal of geographical information science IJGIS > vol 21 n° 1-2 (january 2007) . - pp 1 - 20[article]Réservation
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Code-barres Cote Support Localisation Section Disponibilité 079-07011 RAB Revue Centre de documentation En réserve L003 Disponible 079-07012 RAB Revue Centre de documentation En réserve L003 Disponible Thermal re-emission effects on GPS satellites / J. Duha in Journal of geodesy, vol 80 n° 12 (December 2006)
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Titre : Thermal re-emission effects on GPS satellites Type de document : Article/Communication Auteurs : J. Duha, Auteur ; G.B. Afonso, Auteur ; et al., Auteur Année de publication : 2006 Article en page(s) : pp 665 - 674 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie spatiale
[Termes IGN] albedo
[Termes IGN] émission thermique
[Termes IGN] modèle mathématique
[Termes IGN] orbitographie
[Termes IGN] perturbation orbitale
[Termes IGN] photon
[Termes IGN] rayonnement solaire
[Termes IGN] satellite GPSRésumé : (Auteur) Highly precise satellite-derived coordinates depend on accurate orbit predictions, which cannot be achieved with purely empirical models. Global positioning system (GPS) satellites undergo several periodic perturbing forces that have to be modeled and understood. In this scenario, small non-gravitational forces can no longer be neglected when the purpose of the orbital analysis is to obtain accurate results (Vilhena de Moraes 1994). Together with solar radiation pressure, thermal re-emission effects due to solar heating and Earth albedo are the two most important non-gravitational effects. While solar radiation pressure is widely understood, our knowledge about thermal re-emission effects on GPS satellites is in its infancy. Few models have been proposed in recent years and despite the interest of the scientific community, there is a lack of detailed results concerning the magnitude and the behavior of such forces. The aim of this work is to provide a thermal re-emission force model for GPS satellites, simple enough to minimize the problem of modeling a satellite of complex shape with several components on its surface, but accurate enough to provide an estimate of the magnitude and the behavior of these forces, as well as to provide some input to the present knowledge about photon thrust on GPS satellites. Some results of this work point to the fact that thermal re-emission effects are good candidates to partially explain the Y-bias for GPS satellites. Copyright Springer Numéro de notice : A2006-538 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-006-0060-x En ligne : https://doi.org/10.1007/s00190-006-0060-x Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=28261
in Journal of geodesy > vol 80 n° 12 (December 2006) . - pp 665 - 674[article]Réservation
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Code-barres Cote Support Localisation Section Disponibilité 266-06111 RAB Revue Centre de documentation En réserve L003 Disponible 266-06112 RAB Revue Centre de documentation En réserve L003 Disponible The triumph of GIOVE-A: the first Galileo satellite / J. Benedicto in ESA bulletin, n° 127 (August 2006)
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Titre : The triumph of GIOVE-A: the first Galileo satellite Type de document : Article/Communication Auteurs : J. Benedicto, Auteur ; G. Gatti, Auteur ; A. Garutti, Auteur Année de publication : 2006 Article en page(s) : pp 62 - 62 Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Missions spatiales
[Termes IGN] constellation Galileo
[Termes IGN] GIOVE (satellite)
[Termes IGN] mission spatiale
[Termes IGN] signal GalileoRésumé : (Auteur) Shortly before the end of 2005, the first Galileo experimental satellite was successfully launched. Two weeks later, GIOVE-A transmitted its first navigation signals from orbit achieving a major milestone in the Galileo satellite navigation programme. Copyright European Space Agency Numéro de notice : A2006-369 Affiliation des auteurs : IGN (1940-2011) Thématique : IMAGERIE/POSITIONNEMENT Nature : Article DOI : sans En ligne : http://www.esa.int/esapub/bulletin/bulletin127/bul127i_benedicto.pdf Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=28093
in ESA bulletin > n° 127 (August 2006) . - pp 62 - 62[article]Searching for Galileo: reception and analysis of signals from GIOVE-A / M.L. Psiaki in GPS world, vol 17 n° 6 (June 2006)PermalinkShaping euro navigation / T. Deloye in GEO: Geoconnexion international, vol 5 n° 5 (may 2006)PermalinkThe system: policy and system news and developments GPS/Galileo/GLONASS / J. Spaans in GPS world, vol 17 n° 4 (April 2006)PermalinkNew, improved GPS: the legacy accuracy improvement initiative / T. Creel in GPS world, vol 17 n° 3 (March 2006)PermalinkGalileo opportunities: level playing field for industry / P. Verhoef in GPS world, vol 17 n° 2 (February 2006)PermalinkContracts and promising test results: update Galileo, EGNOS, Glonass and GPS / Huibert-Jan Lekkerkerk in Geoinformatics, vol 9 n° 1 (01/01/2006)PermalinkNaviguer dans le monde sans fil : un aperçu de l'influence exercée par la technologie sans fil sur les topographes / N. Pugh in XYZ, n° 104 (septembre - novembre 2005)PermalinkGalileo test user segment: first achievements and application / M. Hollreiser in GPS world, vol 16 n° 7 (July 2005)PermalinkLaunching Galileo / O. Onidi in Galileo's world, vol 4 n° 2 (01/09/2002)PermalinkQuo vadis, Galileo / V. Ashkenazi in Galileo's world, vol 4 n° 2 (01/09/2002)Permalink