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Galileo performance: GPS interoperability and discriminators for urban and indoor environments / M. O'donnell in GPS world, vol 14 n° 6 (June 2003)
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Titre : Galileo performance: GPS interoperability and discriminators for urban and indoor environments Type de document : Article/Communication Auteurs : M. O'donnell, Auteur ; T. Watson, Auteur ; J. Fisher, Auteur ; et al., Auteur Année de publication : 2003 Article en page(s) : pp 38 - 45 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie spatiale
[Termes IGN] densité de population
[Termes IGN] Europe (géographie politique)
[Termes IGN] Galileo
[Termes IGN] interopérabilité
[Termes IGN] milieu urbain
[Termes IGN] population urbaine
[Termes IGN] positionnement en intérieur
[Termes IGN] signal Galileo
[Termes IGN] signal GPSRésumé : (Auteur) A technical study examines potential discriminators for Galileo mass-market acceptance in the presence of a freely available GPS service. This approach seeks to provide commercial input to the Galileo signal design process, to optimize the GPS + Galileo "super constellation" for urban operation over Europe. The analysis further shows that GPS alone does not offer sufficient availability for "transparent" mass-market use in densely populated areas. Copyright Questex Media Group Inc Numéro de notice : A2003-423 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article DOI : sans Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=26503
in GPS world > vol 14 n° 6 (June 2003) . - pp 38 - 45[article]Exemplaires(1)
Code-barres Cote Support Localisation Section Disponibilité 067-03061 RAB Revue Centre de documentation En réserve L003 Disponible Multipath mitigation: how good can it get with new signals ? / L.R. Weill in GPS world, vol 14 n° 6 (June 2003)
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Titre : Multipath mitigation: how good can it get with new signals ? Type de document : Article/Communication Auteurs : L.R. Weill, Auteur Année de publication : 2003 Article en page(s) : pp 106 - 106 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie spatiale
[Termes IGN] bruit blanc
[Termes IGN] classification par maximum de vraisemblance
[Termes IGN] code GPS
[Termes IGN] correction du signal
[Termes IGN] densité spectrale de puissance
[Termes IGN] signal GPS
[Termes IGN] trajet multipleRésumé : (Auteur) Answer: The winner of the 1971 Nobel Prize for Physics. The question? Who defined the most important signal parameter for controlling GPS multipath? The British/Hungarian physicist Dennis Gabor won the prize for the invention of holography. However, Gabor was also one of a handful of mathematicians and scientists who developed communication theory during the 1940s. Communication theory, also called information theory, is the branch of mathematics that deals with the efficient and accurate transmission of information-bearing signals from one place to another. Key to the theory is the concept of signal bandwidth. Now bandwidth can be defined in a number of different ways, but the particular bandwidth named after Cabor determines, in part, how accurately a GPS receiver can measure pseudorange or carrier phase in the presence of multipath. The Gabor bandwidth is determined by the particular shape of the signal's power spectral density function, and the larger the bandwidth the more resistant is the signal to multipath. The GPS receiver must have a processor that takes advantage of this resistance to provide measurements with minimal multipath contamination. Here, Dr Lawrence Weill outlines an implementation of a multipath mitigation algorithm based on the statistical theory of maximum likelihood and describes its expected performance with the new GPS signals soon to be available - signals characterized by a higher Cabor bandwidth than those currently transmitted. Numéro de notice : A2003-424 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article DOI : sans Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=26504
in GPS world > vol 14 n° 6 (June 2003) . - pp 106 - 106[article]Exemplaires(1)
Code-barres Cote Support Localisation Section Disponibilité 067-03061 RAB Revue Centre de documentation En réserve L003 Disponible Monitoring the ionosphere with GPS: space weather / Anthea Coster in GPS world, vol 14 n° 5 (May 2003)
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Titre : Monitoring the ionosphere with GPS: space weather Type de document : Article/Communication Auteurs : Anthea Coster, Auteur ; J. Foster, Auteur ; P. Erickson, Auteur Année de publication : 2003 Article en page(s) : pp 42 - 49 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Applications de géodésie spatiale
[Termes IGN] données GPS
[Termes IGN] ionosphère
[Termes IGN] magnétosphère
[Termes IGN] rayonnement ultraviolet
[Termes IGN] surveillance météorologique
[Termes IGN] tempête
[Termes IGN] teneur totale en électronsRésumé : (Auteur) Here on Earth, high winds, heavy rains, deep snow, and other forms of severe weather can disrupt our daily lives. Conditions on the Sun and in the solar wind, magnetosphere, and the ionosphere can also affect our lives through the effects they have on satellites, communications, navigation, and power systems. Scientists are now studying space weather with a wide range of tools to try to learn more about the physical and chemical processes taking place in the upper atmosphere and beyond. One of these tools is GPS. The signals from the GPS satellites travel through the ionosphere on their way to receivers on or near Earth's surface. The free electrons populating this region of the atmosphere affect the propagation of the signals, changing their speed and direction of travel. By processing the data from a dual-frequency GPS receiver, it's actually possible to estimate just how many electrons were encountered by the signal along its travel path - the total electron content (TEC). TEC is the number of electrons in a column with a cross-sectional area of one square meter centered on the signal path. If a regional network of ground-based GPS receivers is used, then a map of TEC above the region can be constructed. The TEC normally varies smoothly from day to night as Earth's dayside atmosphere is ionized by the Sun's extreme ultraviolet radiation, while the nightside ionosphere electron content is reduced by chemical recombination. But the ionosphere can experience stormy weather just as the lower atmosphere does. Smooth variations in TEC are replaced by rapid fluctuations, and some regions experience significantly higher or lower TEC values than normal. In this month's column, we look at how GPS is being used to study such storms and how it is furthering our understanding of the Earth-Sun environment. Numéro de notice : A2003-421 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article DOI : sans Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=26501
in GPS world > vol 14 n° 5 (May 2003) . - pp 42 - 49[article]Exemplaires(1)
Code-barres Cote Support Localisation Section Disponibilité 067-03051 RAB Revue Centre de documentation En réserve L003 Disponible Remaining error sources in the nutation at the submilliarc second level / Véronique Dehant in Journal of geophysical research : Solid Earth, vol 108 n° 5 (May 2003)
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Titre : Remaining error sources in the nutation at the submilliarc second level Type de document : Article/Communication Auteurs : Véronique Dehant, Auteur ; Martine Feissel-Vernier , Auteur ; Olivier de Viron, Auteur ; C. Ma, Auteur ; D.T. Yseboodt, Auteur ; Christian Bizouard, Auteur
Année de publication : 2003 Article en page(s) : pp 13-1 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie physique
[Termes IGN] interférométrie à très grande base
[Termes IGN] nutationRésumé : (auteur) Earth's precession and nutations are mainly generated by the luni-solar tidal torque. Diurnal retrograde variations in the atmospheric and oceanic angular momenta in an Earth-fixed reference system induce some additional nutation motions. Observed precession and nutations are derived from very long baseline interferometry (VLBI) data, assuming that the direction of the observed quasars are fixed in space. In this study, we consider the effects of two possible causes for explaining discrepancies between the observed nutations and those modeled in MHB2000 (model adopted by the International Astronomical Union): (1) the time variations in the atmospheric (and potentially oceanic) forcing of the nutations, of the free core nutation (FCN), and of the free inner core nutation (FICN), and (2) the possible contamination of VLBI-derived nutation amplitudes by apparent changes in the directions of the extragalactic radio sources. The robustness of MHB2000 is tested by perturbing some of the parameters and assessing the validity of the resulting nutation amplitudes against realistic estimations. We show that even allowing for large discrepancies related to atmospheric forcing, the ranges of the possible changes in the FCN and FICN periods and damping factors are small. Numéro de notice : A2003-472 Affiliation des auteurs : IGN+Ext (1940-2011) Thématique : POSITIONNEMENT Nature : Article DOI : 10.1029/2002JB001763 Date de publication en ligne : 24/05/2003 En ligne : https://doi.org/10.1029/2002JB001763 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=102730
in Journal of geophysical research : Solid Earth > vol 108 n° 5 (May 2003) . - pp 13-1[article]Synergetic fusion of GPS and photogrammetrically generated elevation models / Jon P. Mills in Photogrammetric Engineering & Remote Sensing, PERS, vol 69 n° 4 (April 2003)
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Titre : Synergetic fusion of GPS and photogrammetrically generated elevation models Type de document : Article/Communication Auteurs : Jon P. Mills, Auteur ; S.J. Buckley, Auteur ; H.L. Mitchell, Auteur Année de publication : 2003 Article en page(s) : pp 341 - 349 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Photogrammétrie numérique
[Termes IGN] appariement géométrique
[Termes IGN] coût
[Termes IGN] données GPS
[Termes IGN] erreur systématique
[Termes IGN] fusion de données
[Termes IGN] GPS en mode cinématique
[Termes IGN] image numérique
[Termes IGN] méthode des moindres carrés
[Termes IGN] modèle numérique de surface
[Termes IGN] orientation relative
[Termes IGN] photographie aérienne
[Termes IGN] point d'appui
[Termes IGN] restitutionRésumé : (Auteur) Digital elevation models (DEMs) produced from photogrammetric data sources have long relied on the use of ground control points to give them scale and orientation. However, in areas such as coastlines, landslides, or glaciers, where identification of suitable natural features and premarking is difficult, the use of conventional ground control may be unfeasible. This paper reports on research that uses independently collected DEMs derived from kinematic GPS to orient surfaces produced by aerial photogrammetric methods, using a leastsquares surface matching algorithm. During algorithm development, three stages of testing were carried out, Using increasingly more complex datasets. Initially, simulated surfaces were used to validate the matching theory and program. Then, a DEM derived from conventional aerial photography was matched with a GPS model, highlighting the effectiveness of surface matching to recover systematic errors in datosets. Finally, surfaces derived from small format digital imagery were successfully fused with wireframe GPS surfaces, the high redundancy and automation potential creating an elegant and cheaper alternative to photocontrol. Numéro de notice : A2003-109 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Article DOI : 10.14358/PERS.69.4.341 En ligne : https://doi.org/10.14358/PERS.69.4.341 Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=22405
in Photogrammetric Engineering & Remote Sensing, PERS > vol 69 n° 4 (April 2003) . - pp 341 - 349[article]Combinaison de séries temporelles des positions des stations et des paramètres de rotation de la Terre / Zuheir Altamimi in Bulletin d'information scientifique et technique de l'IGN, n° 74 (mars 2003)
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PermalinkDéveloppement d'un lidar Raman pour le sondage de la vapeur d'eau et la correction des délais troposphériques en GPS / Olivier Bock in Bulletin d'information scientifique et technique de l'IGN, n° 74 (mars 2003)
PermalinkLe levé laser aéroporté : techniques, applications et recherche / Olivier de Joinville in Bulletin d'information scientifique et technique de l'IGN, n° 74 (mars 2003)
PermalinkSurveillance du trafic au sol par multi-altération mode S / B. Boullard in XYZ, n° 94 (mars - mai 2003)
PermalinkMacdonald Dettwiler real-time emergency management via satellite: status update and future directions / D. Hargreaves in ISPRS Journal of photogrammetry and remote sensing, vol 57 n° 4 (February - March 2003)
PermalinkPermalinkAmélioration de la précision de la localisation différentielle temps réel par mesure de phase des systèmes GNSS / Stéphane Durand (2003)
PermalinkAnalyse und Optimierung geodätischer Messanordnungen unter besonderer Berücksichtigung des Intervallansatzes / S. Schön (2003)
PermalinkLes collectivités misent sur les stations GPS permanentes / Françoise de Blomac in SIG la lettre, n° 43 (janvier 2003)
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