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The geopotential value W 0 for specifying the relativistic atomic time scale and a global vertical reference system / M. Bursa in Journal of geodesy, vol 81 n° 2 (February 2007)  

Public [article]  inJournal of geodesy > vol 81 n° 2 (February 2007) . - pp 103 - 110 Titre : The geopotential value W 0 for specifying the relativistic atomic time scale and a global vertical reference system Type de document : Article/Communication Auteurs : M. Bursa, Auteur ; S. Kenyon, Auteur ; Jan Kouba, Auteur ; et al., Auteur Année de publication : 2007 Article en page(s) : pp 103 - 110 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie physique [Termes IGN] modèle de géopotentiel [Termes IGN] monde (géographie politique) [Termes IGN] système de référence altimétrique [Termes IGN] temps atomique international Résumé : (Auteur) The TOPEX/Poseidon (T/P) satellite alti- meter mission marked a new era in determining the geopotential constant W 0. On the basis of T/P data during 1993–2003 (cycles 11–414), long-term variations in W 0 have been investigated. The rounded value W 0 = 62636856.0 1 0.5) m 2 s -2 has already been adopted by the International Astronomical Union for the definition of the constant L G = W 0/c 2 = 6.969290134 * 10-10 (where c is the speed of light), which is required for the realization of the relativistic atomic time scale. The constant L G , based on the above value of W 0, is also included in the 2003 International Earth Rotation and Reference Frames Service conventions. It has also been suggested that W 0 is used to specify a global vertical reference system (GVRS). W 0 ensures the consistency with the International Terrestrial Reference System, i.e. after adopting W 0, along with the geocentric gravitational constant (GM), the Earth’s rotational velocity (?) and the second zonal geopotential coefficient (J 2) as primary constants (parameters), then the ellipsoidal parameters (a,?) can be computed and adopted as derived parameters. The scale of the International Terrestrial Reference Frame 2000 (ITRF2000) has also been specified with the use of W 0 to be consistent with the geocentric coordinate time. As an example of using W 0 for a GVRS realization, the geopotential difference between the adopted W 0 and the geopotential at the Rimouski tide-gauge point, specifying the North American Vertical Datum 1988 (NAVD88), has been estimated. Copyright Springer Numéro de notice : A2007-046 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-006-0091-3 En ligne : https://doi.org/10.1007/s00190-006-0091-3 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=28411 [article]

Exemplaires(2)

Code-barres	Cote	Support	Localisation	Section	Disponibilité
266-07021	RAB	Revue	Centre de documentation	En réserve L003	Disponible
266-07022	RAB	Revue	Centre de documentation	En réserve L003	Disponible

Calibration errors on experimental slant total electron content (TEC) determined with GPS / L. Ciraolo in Journal of geodesy, vol 81 n° 2 (February 2007)  

Public [article]  inJournal of geodesy > vol 81 n° 2 (February 2007) . - pp 111 - 120 Titre : Calibration errors on experimental slant total electron content (TEC) determined with GPS Type de document : Article/Communication Auteurs : L. Ciraolo, Auteur ; F. Azpilicueta, Auteur ; C. Brunini, Auteur ; et al., Auteur Année de publication : 2007 Article en page(s) : pp 111 - 120 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Applications de géodésie spatiale [Termes IGN] correction ionosphérique [Termes IGN] erreur systématique [Termes IGN] phase GPS [Termes IGN] positionnement par GPS [Termes IGN] propagation ionosphérique [Termes IGN] teneur totale en électrons [Termes IGN] trajet multiple Résumé : (Auteur) The Global Positioning System (GPS) has become a powerful tool for ionospheric studies. In addition, ionospheric corrections are necessary for the augmentation systems required for Global Navigation Satellite Systems (GNSS) use. Dual-frequency carrier-phase and code-delay GPS observations are combined to obtain ionospheric observables related to the slant total electron content (sTEC) along the satellite-receiver line-of-sight (LoS). This observable is affected by inter-frequency biases [IFB; often called differential code biases (DCB)] due to the transmitting and the receiving hardware. These biases must be estimated and eliminated from the data in order to calibrate the experimental sTEC obtained from GPS observations. Based on the analysis of single differences of the ionospheric observations obtained from pairs of co-located dual-frequency GPS receivers, this research addresses two major issues: (1) assessing the errors translated from the code-delay to the carrier-phase ionospheric observable by the so-called levelling process, applied to reduce carrier-phase ambiguities from the data; and (2) assessing the short-term stability of receiver IFB. The conclusions achieved are: (1) the levelled carrier-phase ionospheric observable is affected by a systematic error, produced by code-delay multi-path through the levelling procedure; and (2) receiver IFB may experience significant changes during 1 day. The magnitude of both effects depends on the receiver/antenna configuration. Levelling errors found in this research vary from 1.4 total electron content units (TECU) to 5.3 TECU. In addition, intra-day vaiations of code-delay receiver IFB ranging from 1.4 to 8.8 TECU were detected. Copyright Springer Numéro de notice : A2007-047 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-006-0093-1 En ligne : https://doi.org/10.1007/s00190-006-0093-1 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=28412 [article]

Exemplaires(2)

Code-barres	Cote	Support	Localisation	Section	Disponibilité
266-07021	RAB	Revue	Centre de documentation	En réserve L003	Disponible
266-07022	RAB	Revue	Centre de documentation	En réserve L003	Disponible

Efficiency of carrier-phase integer ambiguity resolution for precise GPS positioning in noisy environments / L. Zhu in Journal of geodesy, vol 81 n° 2 (February 2007)  

Public [article]  inJournal of geodesy > vol 81 n° 2 (February 2007) . - pp 149 - 156 Titre : Efficiency of carrier-phase integer ambiguity resolution for precise GPS positioning in noisy environments Type de document : Article/Communication Auteurs : L. Zhu, Auteur ; Y.C. Lai, Auteur ; M. Shah, Auteur ; et al., Auteur Année de publication : 2007 Article en page(s) : pp 149 - 156 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie spatiale [Termes IGN] ambiguïté entière [Termes IGN] brouillage [Termes IGN] bruit (théorie du signal) [Termes IGN] méthode des moindres carrés [Termes IGN] phase GPS [Termes IGN] positionnement par GPS [Termes IGN] résolution d'ambiguïté Résumé : (Auteur) Precise GPS positioning relies on tracking the carrier-phase. The fractional part of carrier-phase can be measured directly using a standard phase-locked loop, but the integer part is ambiguous and the ambiguity must be resolved based on sequential carrier-phase measurements to ensure the required positioning precision. In the presence of large phase-measurement noise, as can be expected in a jamming environment for example, the amount of data required to resolve the integer ambiguity can be large, which requires a long time for any generic integer parameter estimation algorithm to converge. A key question of interest in significant applications of GPS where fast and accurate positioning is desired is then how the convergence time depends on the noise amplitude. Here we address this question by investigating integer least-squares estimation algorithms. Our theoretical derivation and numerical experiments indicate that the convergence time increases linearly with the noise variance, suggesting a less stringent requirement for the convergence time than intuitively expected, even in a jamming environment where the phase noise amplitude is large. This finding can be useful for practical design of GPS-based systems in a jamming environment, for which the ambiguity resolution time for precise positioning may be critical. Copyright Springer Numéro de notice : A2007-048 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-006-0096-y En ligne : https://doi.org/10.1007/s00190-006-0096-y Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=28413 [article]

Exemplaires(2)

Code-barres	Cote	Support	Localisation	Section	Disponibilité
266-07021	RAB	Revue	Centre de documentation	En réserve L003	Disponible
266-07022	RAB	Revue	Centre de documentation	En réserve L003	Disponible

Modeling long-period noise in kinematic GPS applications / A. Borsa in Journal of geodesy, vol 81 n° 2 (February 2007)  

Public [article]  inJournal of geodesy > vol 81 n° 2 (February 2007) . - pp 157 - 170 Titre : Modeling long-period noise in kinematic GPS applications Type de document : Article/Communication Auteurs : A. Borsa, Auteur ; J.B. Minster, Auteur ; B.G. Bills, Auteur ; et al., Auteur Année de publication : 2007 Article en page(s) : pp 157 - 170 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie spatiale [Termes IGN] Bolivie [Termes IGN] bruit (théorie du signal) [Termes IGN] désert [Termes IGN] erreur moyenne quadratique altimétrique [Termes IGN] filtrage du bruit [Termes IGN] GPS en mode cinématique [Termes IGN] problème inverse Résumé : (Auteur) We develop and test an algorithm for modeling and removing elevation error in kinematic GPS trajectories in the context of a kinematic GPS survey of the salar de Uyuni, Bolivia. Noise in the kinematic trajectory ranges over 15 cm and is highly autocorrelated, resulting in significant contamination of the topographic signal. We solve for a noise model using crossover differences at trajectory intersections as constraints in a least-squares inversion. Validation of the model using multiple realizations of synthetic/simulated noise shows an average decrease in root-mean-square-error (RMSE) by a factor of four. Applying the model to data from the salar de Uyuni survey, we find that crossover differences drop by a factor of eight (from an RMSE of 5.6 to 0.7 cm), and previously obscured topographic features are revealed in a plan view of the corrected trajectory. We believe that this algorithm can be successfully adapted to other survey methods that employ kinematic GPS for positioning. Copyright Springer Numéro de notice : A2007-049 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-006-0097-x En ligne : https://doi.org/10.1007/s00190-006-0097-x Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=28414 [article]

Exemplaires(2)

Code-barres	Cote	Support	Localisation	Section	Disponibilité
266-07021	RAB	Revue	Centre de documentation	En réserve L003	Disponible
266-07022	RAB	Revue	Centre de documentation	En réserve L003	Disponible