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Consistent realization of celestial and terrestrial reference frames / Younghee Kwak in Journal of geodesy, vol 92 n° 9 (September 2018)  

Public [article]  inJournal of geodesy > vol 92 n° 9 (September 2018) . - pp 1047 - 1061 Titre : Consistent realization of celestial and terrestrial reference frames Type de document : Article/Communication Auteurs : Younghee Kwak, Auteur ; Mathis Blossfeld, Auteur ; Ralf Schmid, Auteur ; Detlef Angermann, Auteur ; Michael Gerstl, Auteur ; Manuela Seitz, Auteur Année de publication : 2018 Article en page(s) : pp 1047 - 1061 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Systèmes de référence et réseaux [Termes IGN] cohérence des données [Termes IGN] erreur systématique inter-systèmes [Termes IGN] International Terrestrial Reference Frame [Termes IGN] paramètres d'orientation de la Terre [Termes IGN] point de liaison (géodésie) [Termes IGN] système de référence céleste Résumé : (Auteur) The Celestial Reference System (CRS) is currently realized only by Very Long Baseline Interferometry (VLBI) because it is the space geodetic technique that enables observations in that frame. In contrast, the Terrestrial Reference System (TRS) is realized by means of the combination of four space geodetic techniques: Global Navigation Satellite System (GNSS), VLBI, Satellite Laser Ranging (SLR), and Doppler Orbitography and Radiopositioning Integrated by Satellite. The Earth orientation parameters (EOP) are the link between the two types of systems, CRS and TRS. The EOP series of the International Earth Rotation and Reference Systems Service were combined of specifically selected series from various analysis centers. Other EOP series were generated by a simultaneous estimation together with the TRF while the CRF was fixed. Those computation approaches entail inherent inconsistencies between TRF, EOP, and CRF, also because the input data sets are different. A combined normal equation (NEQ) system, which consists of all the parameters, i.e., TRF, EOP, and CRF, would overcome such an inconsistency. In this paper, we simultaneously estimate TRF, EOP, and CRF from an inter-technique combined NEQ using the latest GNSS, VLBI, and SLR data (2005–2015). The results show that the selection of local ties is most critical to the TRF. The combination of pole coordinates is beneficial for the CRF, whereas the combination of ΔUT1 results in clear rotations of the estimated CRF. However, the standard deviations of the EOP and the CRF improve by the inter-technique combination which indicates the benefits of a common estimation of all parameters. It became evident that the common determination of TRF, EOP, and CRF systematically influences future ICRF computations at the level of several μas. Moreover, the CRF is influenced by up to 50 μas if the station coordinates and EOP are dominated by the satellite techniques. Numéro de notice : A2018-458 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-018-1130-6 Date de publication en ligne : 12/03/2018 En ligne : https://doi.org/10.1007/s00190-018-1130-6 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=91055 [article]

Absolute IGS antenna phase center model igs08.atx: status and potential improvements / Ralf Schmid in Journal of geodesy, vol 90 n° 4 (April 2016)  

Public [article]  inJournal of geodesy > vol 90 n° 4 (April 2016) . - pp 343 - 364 Titre : Absolute IGS antenna phase center model igs08.atx: status and potential improvements Type de document : Article/Communication Auteurs : Ralf Schmid, Auteur ; Rolf Dach, Auteur ; Xavier Collilieux , Auteur ; Adrian Jäggi, Auteur ; M. Schmitz, Auteur ; F. Dilssner, Auteur Année de publication : 2016 Article en page(s) : pp 343 - 364 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Systèmes de référence et réseaux [Termes IGN] antenne GNSS [Termes IGN] centre de phase [Termes IGN] étalonnage d'instrument [Termes IGN] International Terrestrial Reference Frame [Termes IGN] orbite basse [Termes IGN] positionnement par GLONASS [Termes IGN] positionnement par GNSS [Termes IGN] positionnement par GPS Résumé : (auteur) On 17 April 2011, all analysis centers (ACs) of the International GNSS Service (IGS) adopted the reference frame realization IGS08 and the corresponding absolute antenna phase center model igs08.atx for their routine analyses. The latter consists of an updated set of receiver and satellite antenna phase center offsets and variations (PCOs and PCVs). An update of the model was necessary due to the difference of about 1 ppb in the terrestrial scale between two consecutive realizations of the International Terrestrial Reference Frame (ITRF2008 vs. ITRF2005), as that parameter is highly correlated with the GNSS satellite antenna PCO components in the radial direction. For the receiver antennas, more individual calibrations could be considered and GLONASS-specific correction values were added. For the satellite antennas, all correction values except for the GPS PCVs were newly estimated considering more data than for the former model. Satellite-specific PCOs for all GPS satellites active since 1994 could be derived from reprocessed solutions of five ACs generated within the scope of the first IGS reprocessing campaign. Two ACs separately derived a full set of corrections for all GLONASS satellites active since 2003. Ignoring scale-related biases, the accuracy of the satellite antenna PCOs is on the level of a few cm. With the new phase center model, orbit discontinuities at day boundaries can be reduced, and the consistency between GPS and GLONASS results is improved. To support the analysis of low Earth orbiter (LEO) data, igs08.atx was extended with LEO-derived PCV estimates for big nadir angles in June 2013. Numéro de notice : A2016-249 Affiliation des auteurs : LASTIG LAREG+Ext (2012-mi2018) Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-015-0876-3 Date de publication en ligne : 23/12/2015 En ligne : http://dx.doi.org/10.1007/s00190-015-0876-3 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=80757 [article]

GNSS satellite geometry and attitude models / Oliver Montenbruck in Advances in space research, vol 56 n° 6 (September 2015)  

Public [article]  inAdvances in space research > vol 56 n° 6 (September 2015) . - pp 1015 - 1029 Titre : GNSS satellite geometry and attitude models Type de document : Article/Communication Auteurs : Oliver Montenbruck, Auteur ; Ralf Schmid, Auteur ; F. Mercier, Auteur ; Peter Steigenberger, Auteur ; et al., Auteur Année de publication : 2015 Article en page(s) : pp 1015 - 1029 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie spatiale [Termes IGN] antenne GNSS [Termes IGN] centre de phase [Termes IGN] données TLS (télémétrie) [Termes IGN] format ANTEX [Termes IGN] satellite de positionnement [Termes IGN] satellite de télémétrie Résumé : (auteur) This article discusses the attitude modes employed by present Global (and Regional) Navigation Satellite Systems (GNSSs) and the models used to describe them along with definitions of the constellation-specific spacecraft body frames. A uniform convention for the labeling of the principal spacecraft axes is proposed by the International GNSS Service (IGS), which results in a common formulation of the nominal attitude of all GNSS satellites in yaw-steering mode irrespective of their specific orbit and constellation. The conventions defined within this document provide the basis for the specification of antenna phase center offsets and variations in a multi-GNSS version of the IGS absolute phase center model in the ANTEX (antenna exchange) format. To facilitate the joint analysis of GNSS observations and satellite laser ranging measurements, laser retroreflector array coordinates consistent with the IGS-specific spacecraft frame conventions are provided in addition to representative antenna offset values for all GNSS constellations. Numéro de notice : A2015-874 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern En ligne : http://dx.doi.org/10.1016/j.asr.2015.06.019 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=79376 [article]

Evaluation of the ITRF2008 GPS vertical velocities using satellite antenna z-offsets / Xavier Collilieux in GPS solutions, vol 17 n° 2 (April 2013)  

Public [article]  inGPS solutions > vol 17 n° 2 (April 2013) . - pp 237 - 246 Titre : Evaluation of the ITRF2008 GPS vertical velocities using satellite antenna z-offsets Type de document : Article/Communication Auteurs : Xavier Collilieux , Auteur ; Ralf Schmid, Auteur Année de publication : 2013 Article en page(s) : pp 237 - 246 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Systèmes de référence et réseaux [Termes IGN] antenne GNSS [Termes IGN] centre de phase [Termes IGN] filtre de Kalman [Termes IGN] International Terrestrial Reference Frame Résumé : (auteur) We develop a method to evaluate the terrestrial reference frame (TRF) scale rate error using Global Positioning System (GPS) satellite antenna phase center offset (APCO) parameters and apply it to ITRF2008. We search for the TRF in which z-APCO parameters have the smallest drift. In order to provide realistic error bars for the z-APCO drifts, we pay attention to model periodic variations and auto-correlated noise processes in the z-APCO time series. We will show that the GPS scale rate with respect to a frame is, as a first approximation, proportional to the estimated mean z-APCO trend if that frame is used to constrain station positions. Thus, an ITRF2008 scale rate error between - 0.27 and - 0.06 mm/yr depending on the GPS analysis center can be estimated, which demonstrates the high quality of the newly constructed ITRF2008. We will also demonstrate that the traditional estimates of the GPS scale rate from 7-parameter similarity transformations are consistent with our newly derived GPS scale rates with respect to ITRF2008 within two sigmas. We find using International GNSS Service (IGS) products that the traditional approach is relevant for scale rate determination even if some of the z-APCO values supplied by the IGS were not simultaneously calibrated. As the scale rate is related to the accuracy of vertical velocities, our estimates supply a conservative evaluation that can be used for error budget computation. Numéro de notice : A2013-850 Affiliation des auteurs : LASTIG LAREG+Ext (2012-mi2018) Thématique : POSITIONNEMENT Nature : Article DOI : 10.1007/s10291-012-0274-8 Date de publication en ligne : 11/07/2012 En ligne : http://dx.doi.org/10.1007/s10291-012-0274-8 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=80131 [article]

Dependence of IGS products on the ITRF datum / Jim Ray (2013)  

Public contenu dans Reference frames for applications in geosciences, Proceedings of IAG Symposium REFAG 2010 / Zuheir Altamimi (2013)   Titre : Dependence of IGS products on the ITRF datum Type de document : Article/Communication Auteurs : Jim Ray, Auteur ; Paul Rebischung , Auteur ; Ralf Schmid, Auteur Editeur : Berlin, Heidelberg, Vienne, New York, ... : Springer Année de publication : 2013 Collection : International Association of Geodesy Symposia, ISSN 0939-9585 num. 138 Conférence : REFAG 2010, Reference Frames for Applications in Geosciences, IAG symposium 04/10/2010 08/10/2010 Champs-sur-Marne France Importance : pp 63 - 67 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Systèmes de référence et réseaux [Termes IGN] antenne GNSS [Termes IGN] étalonnage d'instrument [Termes IGN] International GNSS Service [Termes IGN] International Terrestrial Reference Frame [Termes IGN] repère de référence Résumé : (Auteur) Throughout its nearly two decades, the International GNSS (Global Navigation Satellite Systems) Service (IGS) has sought to align its products closely to successive realizations of the International Terrestrial Reference Frame (ITRF). This has been disruptive for IGS users at times, especially during the 1990s when some radical ITRF datum choices were adopted. During the past decade, IGS impacts due to ITRF updates have been smaller and mostly caused by errors in the results from the contributing space geodetic techniques. Frame orientations (rotations) are purely conventional, so the IGS relies on the ITRF via a subset of reliable, globally distributed stations. Except for the period when ITRF93 was used, this procedure has worked well. The IGS origin in principle could be self-reliant or contributory to ITRF by direct observation of a frame origin aligned to the long-term center of mass of the entire Earth system. In practice, however, GNSS-based results have been less reliable than those from satellite laser ranging (SLR). So the ITRF origin, based on SLR only, has been adopted historically. Until the transition from ITRF2005 to ITRF2008, there have sometimes been significant origin shifts as SLR results have evolved. However, the present stability of the ITRF origin may finally have reached the few-mm level. In many respects, the IGS dependence on the ITRF scale is most subtle and problematic. In addition to an overall Helmert alignment of the IGS frame to match the ITRF scale (and other datum parameters), since 2006 the IGS calibration values for the GNSS satellite antenna z-offsets depend directly on the same ITRF scale (due to high correlations if the IGS frame scale is not fixed). We therefore face a non-linear situation to maintain full consistency between all IGS products and the ITRF scale: each IGS frame contribution to ITRF based on one set of antenna calibrations must be used, together with frames from other techniques, to determine an updated ITRF and new antenna calibrations, which are then no longer strictly consistent with the starting IGS frame. One can hope that the process will iteratively converge eventually. But large shifts in the ITRF scale, such as the -1 ppb change from ITRF2005 to ITRF2008, are highly disturbing, much more so than the associated rotational or translational shifts. Numéro de notice : C2010-012 Affiliation des auteurs : LAREG+Ext (1991-2011) Thématique : POSITIONNEMENT Nature : Communication nature-HAL : ComAvecCL&ActesPubliésIntl DOI : 10.1007/978-3-642-32998-2_11 Date de publication en ligne : 27/11/2012 En ligne : http://dx.doi.org/10.1007/978-3-642-32998-2_11 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=65067

IGS08 : the IGS realization of ITRF2008 / Paul Rebischung in GPS solutions, vol 16 n° 4 (October 2012)  

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Generation of a consistent absolute phase center correction model for GPS receiver and satellite antennas / Ralf Schmid in Journal of geodesy, vol 81 n° 12 (December 2007)

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