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Termes IGN > sciences naturelles > sciences de la Terre et de l'univers > astronomie > chronométrie > temps solaire > temps universel
temps universelSynonyme(s)UT1 |
Documents disponibles dans cette catégorie (31)
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Improving the modeling of the atmospheric delay in the data analysis of the Intensive VLBI sessions and the impact on the UT1 estimates / Tobias Nilsson in Journal of geodesy, vol 91 n° 7 (July 2017)
[article]
Titre : Improving the modeling of the atmospheric delay in the data analysis of the Intensive VLBI sessions and the impact on the UT1 estimates Type de document : Article/Communication Auteurs : Tobias Nilsson, Auteur ; Benedikt Soja, Auteur ; Kyriakos Balidakis, Auteur ; Maria Karbon, Auteur ; Robert Heinkelmann, Auteur ; Zhiguo Deng, Auteur ; Harald Schuh, Auteur Année de publication : 2017 Article en page(s) : pp 857 - 866 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie spatiale
[Termes IGN] analyse de données
[Termes IGN] filtre de Kalman
[Termes IGN] gradient de troposphère
[Termes IGN] interférométrie à très grande base
[Termes IGN] longueur du jour
[Termes IGN] modèle atmosphérique
[Termes IGN] retard troposphérique zénithal
[Termes IGN] temps universelRésumé : (Auteur) The very long baseline interferometry (VLBI) Intensive sessions are typically 1-h and single-baseline VLBI sessions, specifically designed to yield low-latency estimates of UT1-UTC. In this work, we investigate what accuracy is obtained from these sessions and how it can be improved. In particular, we study the modeling of the troposphere in the data analysis. The impact of including external information on the zenith wet delays (ZWD) and tropospheric gradients from GPS or numerical weather prediction models is studied. Additionally, we test estimating tropospheric gradients in the data analysis, which is normally not done. To evaluate the results, we compared the UT1-UTC values from the Intensives to those from simultaneous 24-h VLBI session. Furthermore, we calculated length of day (LOD) estimates using the UT1-UTC values from consecutive Intensives and compared these to the LOD estimated by GPS. We find that there is not much benefit in using external ZWD; however, including external information on the gradients improves the agreement with the reference data. If gradients are estimated in the data analysis, and appropriate constraints are applied, the WRMS difference w.r.t. UT1-UTC from 24-h sessions is reduced by 5% and the WRMS difference w.r.t. the LOD from GPS by up to 12%. The best agreement between Intensives and the reference time series is obtained when using both external gradients from GPS and additionally estimating gradients in the data analysis. Numéro de notice : A2017-298 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-016-0985-7 En ligne : http://doi.org/10.1007/s00190-016-0985-7 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=85333
in Journal of geodesy > vol 91 n° 7 (July 2017) . - pp 857 - 866[article]Springer handbook of Global Navigation Satellite Systems / Peter J.G. Teunissen (2017)
Titre : Springer handbook of Global Navigation Satellite Systems Type de document : Guide/Manuel Auteurs : Peter J.G. Teunissen, Éditeur scientifique ; Oliver Montenbruck, Éditeur scientifique Editeur : Springer International Publishing Année de publication : 2017 Importance : 1327 Format : 20 x 27 cm ISBN/ISSN/EAN : 978-3-319-42926-7 Note générale : Bibliographie et glossaire Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie spatiale
[Termes IGN] antenne GNSS
[Termes IGN] BeiDou
[Termes IGN] couplage GNSS-INS
[Termes IGN] filtre de Kalman
[Termes IGN] Galileo
[Termes IGN] géodynamique
[Termes IGN] Global Navigation Satellite System
[Termes IGN] Global Orbitography Navigation Satellite System
[Termes IGN] horloge atomique
[Termes IGN] interférence
[Termes IGN] ionosphère
[Termes IGN] méthode des moindres carrés
[Termes IGN] orbitographie
[Termes IGN] orientation
[Termes IGN] positionnement différentiel
[Termes IGN] positionnement ponctuel précis
[Termes IGN] précision du positionnement
[Termes IGN] récepteur GNSS
[Termes IGN] réflectométrie par GNSS
[Termes IGN] résolution d'ambiguïté
[Termes IGN] signal GNSS
[Termes IGN] système d'extension
[Termes IGN] temps universel
[Termes IGN] traitement du signal
[Termes IGN] trajet multipleIndex. décimale : 30.61 Systèmes de Positionnement par Satellites du GNSS Résumé : (Editeur) This Handbook presents a complete and rigorous overview of the fundamentals, methods and applications of the multidisciplinary field of Global Navigation Satellite Systems (GNSS), providing an exhaustive, one-stop reference work and a state-of-the-art description of GNSS as a key technology for science and society at large. All global and regional satellite navigation systems, both those currently in operation and those under development (GPS, GLONASS, Galileo, BeiDou, QZSS, IRNSS/NAVIC, SBAS), are examined in detail. The functional principles of receivers and antennas, as well as the advanced algorithms and models for GNSS parameter estimation, are rigorously discussed. The book covers the broad and diverse range of land, marine, air and space applications, from everyday GNSS to high-precision scientific applications and provides detailed descriptions of the most widely used GNSS format standards, covering receiver formats as well as IGS product and meta-data formats. The full coverage of the field of GNSS is presented in seven parts, from its fundamentals, through the treatment of global and regional navigation satellite systems, of receivers and antennas, and of algorithms and models, up to the broad and diverse range of applications in the areas of positioning and navigation, surveying, geodesy and geodynamics, and remote sensing and timing. Each chapter is written by international experts and amply illustrated with figures and photographs, making the book an invaluable resource for scientists, engineers, students and institutions alike. Note de contenu :
PRINCIPLES OF GNSS
1. Introduction to GNSS
2. Time and reference systems
3. Satellite orbits and attitude
4. Signals and modulation
5. Clocks
6. Atmospheric signal propagation
SATELLITE NAVIGATION SYSTEMS
7. The Global Positioning System (GPS)
8. GLONASS
9. Galileo
10. Chinese navigation satellite systems
11. Regional systems
12. Satellite based augmentation systems
GNSS RECEIVERS AND ANTENNAS
13. Receiver architecture
14. Signal processing
15. Multipath
16. Interference
17. Antennas
18. Simulators and test equipment
GNSS algorithms and models
19. Basic observation equations
20. Combinations of observations
21. Positioning model
22. Least-squares estimation and Kalman filtering
23. Carrier phase integer ambiguity resolution
24. Batch and recursive model validation
POSITIONING AND NAVIGATION
25. Precise point positioning
26. Differential positioning
27. Attitude determination
28. GNSS/INS integration
29. Land and maritime applications
30. Aviation applications
31. Ground based augmentation systems
32. Space applications
SURVEYING, GEODESY AND GEODYNAMICS
33. The international GNSS service
34. Orbit and clock product generation
35. Surveying
36. Geodesy
37. Geodynamics
GNSS REMOTE SENSING AND TIMING
38. Monitoring of the neutral atmosphere
39. Ionosphere monitoring
40. Reflectometry
41. GNSS time and frequency transfer
Annex A: Data formats
Annex B: GNSS parametersNuméro de notice : 22723 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Manuel Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=85346 ContientExemplaires(3)
Code-barres Cote Support Localisation Section Disponibilité 22723-04 DEP-EXG Livre Equipe Géodésie Dépôt en unité Exclu du prêt 22723-03 DEP-ELG Livre Marne-la-Vallée Dépôt en unité Exclu du prêt 22723-02 DEP-PMC Livre Saint-Mandé Dépôt en unité Exclu du prêt Asymmetric tropospheric delays from numerical weather models for UT1 determination from VLBI Intensive sessions on the baseline Wettzell–Tsukuba / Johannes Böhm in Journal of geodesy, vol 84 n° 5 (May 2010)
[article]
Titre : Asymmetric tropospheric delays from numerical weather models for UT1 determination from VLBI Intensive sessions on the baseline Wettzell–Tsukuba Type de document : Article/Communication Auteurs : Johannes Böhm , Auteur ; T. Hobiger, Auteur ; R. Ichikawa, Auteur ; et al., Auteur Année de publication : 2010 Article en page(s) : pp 319 - 325 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie spatiale
[Termes IGN] interférométrie à très grande base
[Termes IGN] Japon
[Termes IGN] ligne de base
[Termes IGN] modèle atmosphérique
[Termes IGN] propagation troposphérique
[Termes IGN] temps universel
[Termes IGN] WettzellRésumé : (Auteur) One-baseline 1-h Very Long Baseline Interferometry (VLBI) Intensive sessions are carried out every day to determine Universal Time (UT1). Azimuthal asymmetry of tropospheric delays around the stations is usually ignored and not estimated because of the small number of observations. In this study we use external information about the asymmetry for the Intensive sessions between Tsukuba (Japan) and Wettzell (Germany), which are carried out on Saturdays and Sundays (1) from direct ray-tracing for each observation at Tsukuba and (2) in the form of linear horizontal north and east gradients every 6 h at both stations. The change of the UT1 estimates is at the 10 us level with maximum differences of up to 50 us, which is clearly above the formal uncertainties of the UT1 estimates (between 5 and 20 us). Spectral analysis reveals that delays from direct ray-tracing for the station Tsukuba add significant power at short periods (1–2 weeks) w.r.t. the state-of-the-art approach, and comparisons with length-of-day (LOD) estimates from Global Positioning System (GPS) indicate that these ray-traced delays slightly improve the UT1 estimates from Intensive sessions. Numéro de notice : A2010-184 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-010-0370-x Date de publication en ligne : 05/03/2010 En ligne : https://doi.org/10.1007/s00190-010-0370-x Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=30379
in Journal of geodesy > vol 84 n° 5 (May 2010) . - pp 319 - 325[article]Exemplaires(1)
Code-barres Cote Support Localisation Section Disponibilité 266-2010051 SL Revue Centre de documentation Revues en salle Disponible The impact of errors in polar motion and nutation on UT1 determinations from VLBI Intensive observations / Axel Nothnagel in Journal of geodesy, vol 82 n° 12 (December 2008)
[article]
Titre : The impact of errors in polar motion and nutation on UT1 determinations from VLBI Intensive observations Type de document : Article/Communication Auteurs : Axel Nothnagel, Auteur ; D. Schnell, Auteur Année de publication : 2008 Article en page(s) : pp 863 - 869 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie physique
[Termes IGN] compensation
[Termes IGN] données ITGB
[Termes IGN] écart type
[Termes IGN] erreur systématique
[Termes IGN] mouvement du pôle
[Termes IGN] nutation
[Termes IGN] temps universelRésumé : (Auteur) The earth’s phase of rotation, expressed as Universal Time UT1, is the most variable component of the earth’s rotation. Continuous monitoring of this quantity is realised through daily single-baseline VLBI observations which are interleaved with VLBI network observations. The accuracy of these single-baseline observations is established mainly through statistically determined standard deviations of the adjustment process although the results of these measurements are prone to systematic errors. The two major effects are caused by inaccuracies in the polar motion and nutation angles introduced as a priori values which propagate into the UT1 results. In this paper, we analyse the transfer of these components into UT1 depending on the two VLBI baselines being used for short duration UT1 monitoring. We develop transfer functions of the errors in polar motion and nutation into the UT1 estimates. Maximum values reach 30 [?s per milliarcsecond] which is quite large considering that observations of nutation offsets w.r.t. the state-of-the-art nutation model show deviations of as much as one milliarcsecond. Copyright Springer Numéro de notice : A2008-470 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-008-0212-2 En ligne : https://doi.org/10.1007/s00190-008-0212-2 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=29539
in Journal of geodesy > vol 82 n° 12 (December 2008) . - pp 863 - 869[article]Exemplaires(2)
Code-barres Cote Support Localisation Section Disponibilité 266-08111 RAB Revue Centre de documentation En réserve L003 Disponible 266-08112 RAB Revue Centre de documentation En réserve L003 Disponible 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]Exemplaires(1)
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