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Termes descripteurs IGN > sciences naturelles > sciences de la Terre et de l'univers > géosciences > géophysique interne > géodésie > point de liaison (géodésie)
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Modeling the VLBI delay for Earth satellites / Frédéric Jaron in Journal of geodesy, vol 93 n°7 (July 2019)
Titre : Modeling the VLBI delay for Earth satellites Type de document : Article/Communication Auteurs : Frédéric Jaron, Auteur ; Axel Nothnagel, Auteur Année de publication : 2019 Article en page(s) : pp 953 - 961 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie spatiale
[Termes descripteurs IGN] E-GRASP
[Termes descripteurs IGN] Geodetic Reference Antenna in Space
[Termes descripteurs IGN] interférométrie à très grande base
[Termes descripteurs IGN] point de liaison (géodésie)
[Termes descripteurs IGN] poursuite de satellite
[Termes descripteurs IGN] propagation du signal
[Termes descripteurs IGN] retard troposphérique
[Termes descripteurs IGN] système international de référence célesteRésumé : (auteur) Very-long-baseline interferometry (VLBI) observations of satellites orbiting the Earth and emitting an artificial radio signal have the potential of becoming an important technique for improving the frame ties between celestial and terrestrial reference frames. Modeling the delay of the signal reception at one station with respect to the other station of a baseline is a fundamental step for correlation and parameter estimation. The near-field VLBI delay models developed so far include numerical computation, which may become expensive in terms of computation time. This applies especially when partial derivatives are to be computed, which is the normal case for least squares adjustments. Furthermore, all the models are formulated in the barycentric celestial reference system requiring large numbers. Here we present an analytical expression for the VLBI delay for the special case of satellites orbiting the Earth, observed by ground-based radio telescopes. We analytically solve the light time equation for each signal propagation path from the source to receiver one and to receiver two under the simplification of linearizing the trajectory of the satellite. By approximating the motion of the Earth as uniform during the short signal travel times we are able to work in the geocentric celestial reference system. We investigate differences between numerical and analytical solutions by simulating VLBI observations of Earth satellites. These tests reveal that delays computed with the analytical formula are consistent with those computed with the numerical solution below the detection level of VLBI but at less computational cost. Numéro de notice : A2019-354 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-018-1217-0 date de publication en ligne : 20/11/2018 En ligne : https://doi.org/10.1007/s00190-018-1217-0 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=93408
in Journal of geodesy > vol 93 n°7 (July 2019) . - pp 953 - 961[article]
Titre : InSAR Corner Cube at GRSM [diaporama] Type de document : Article/Communication Auteurs : Mourad Aimar, Auteur ; Clément Courde, Auteur ; Xavier Collilieux Editeur : Nice : Université Côte d'Azur Année de publication : 2019 Conférence : ILRS 2019 Technical Workshop on Laser ranging : To improve economy, performance, and adoption for new applications 21/10/2019 25/10/2019 Stuttgart Allemagne programme sans actes Importance : 16 p. Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Systèmes de référence et réseaux
[Termes descripteurs IGN] co-positionnement
[Termes descripteurs IGN] coin réflecteur
[Termes descripteurs IGN] déformation de la croute terrestre
[Termes descripteurs IGN] erreur systématique
[Termes descripteurs IGN] image Sentinel-SAR
[Termes descripteurs IGN] interféromètrie par radar à antenne synthétique
[Termes descripteurs IGN] point de liaison (géodésie)
[Termes descripteurs IGN] rattachement métrologique
[Termes descripteurs IGN] station permanenteRésumé : (auteur) Calern's multi-technical geodetic observatory, is a co-location site for the Côte d'Azur Observatory, which host three different spatial geodesy techniques: an SLR/LLR station, a permanent DORIS station (since september 2018), and two permanent GNSS stations. Ponctually, specialists from the "Institut National de l'Information Géographique et Forestière" (IGN, France) measure the local ties between our different instruments. The objective is to determine the global biases that may exist between each of these techniques. However, local movements (deformation of soil) may take place, that's why ponctual local ties measurement are insufficient. The effective alternative we choose has been the deployment of an INSAR corner cube on our multi-technical site in the summer of 2018. Indeed, the European Space Agency (ESA) offering the SAR images of the Sentinel constellation (S-1A and S-1B), this allows us PSInSAR analyzes thus providing a systematic monitoring of the deformation of the soils of our co-location site, with great precision. After having recalled in the introduction the method of local ties measurement made by the colleagues of the IGN, this presentation will be articulated then around the design, the installation of the corner of cube, and the choice of the orbit of satellite. Numéro de notice : C2019-065 Affiliation des auteurs : ENSG+Ext (2012-2019) Thématique : POSITIONNEMENT Nature : Communication nature-HAL : ComSansActesPubliés-Unpublished DOI : sans En ligne : https://hal.archives-ouvertes.fr/hal-03114069 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=97005
Titre : Assessment of local GNSS baselines at co-location sites Type de document : Article/Communication Auteurs : Iván Herrera Pinzón, Auteur ; Markus Rothacher, Auteur Année de publication : 2018 Article en page(s) : pp 1079 - 1095 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Systèmes de référence et réseaux
[Termes descripteurs IGN] co-positionnement
[Termes descripteurs IGN] erreur systématique
[Termes descripteurs IGN] International Terrestrial Reference Frame
[Termes descripteurs IGN] ligne de base
[Termes descripteurs IGN] point de liaison (géodésie)
[Termes descripteurs IGN] positionnement par GNSS
[Termes descripteurs IGN] retard troposphérique zénithal
[Termes descripteurs IGN] série temporelle
[Termes descripteurs IGN] station permanenteRésumé : (Auteur) As one of the major contributors to the realisation of the International Terrestrial Reference System (ITRS), the Global Navigation Satellite Systems (GNSS) are prone to suffer from irregularities and discontinuities in time series. While often associated with hardware/software changes and the influence of the local environment, these discrepancies constitute a major threat for ITRS realisations. Co-located GNSS at fundamental sites, with two or more available instruments, provide the opportunity to mitigate their influence while improving the accuracy of estimated positions by examining data breaks, local biases, deformations, time-dependent variations and the comparison of GNSS baselines with existing local tie measurements. With the use of co-located GNSS data from a subset sites of the International GNSS Service network, this paper discusses a global multi-year analysis with the aim of delivering homogeneous time series of coordinates to analyse system-specific error sources in the local baselines. Results based on the comparison of different GNSS-based solutions with the local survey ties show discrepancies of up to 10 mm despite GNSS coordinate repeatabilities at the sub-mm level. The discrepancies are especially large for the solutions using the ionosphere-free linear combination and estimating tropospheric zenith delays, thus corresponding to the processing strategy used for global solutions. Snow on the antennas causes further problems and seasonal variations of the station coordinates. These demonstrate the need for a permanent high-quality monitoring of the effects present in the short GNSS baselines at fundamental sites. Numéro de notice : A2018-459 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-017-1108-9 date de publication en ligne : 17/01/2018 En ligne : https://doi.org/10.1007/s00190-017-1108-9 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=91056
in Journal of geodesy > vol 92 n° 9 (September 2018) . - pp 1079 - 1095[article]
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 descripteurs IGN] cohérence des données
[Termes descripteurs IGN] erreur systématique inter-systèmes
[Termes descripteurs IGN] International Terrestrial Reference Frame
[Termes descripteurs IGN] paramètres d'orientation de la Terre
[Termes descripteurs IGN] point de liaison (géodésie)
[Termes descripteurs IGN] système de référence célesteRésumé : (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
in Journal of geodesy > vol 92 n° 9 (September 2018) . - pp 1047 - 1061[article]
Titre : Assessment of the possible contribution of space ties on-board GNSS satellites to the terrestrial reference frame Type de document : Article/Communication Auteurs : Sara Bruni, Auteur ; Paul Rebischung Année de publication : 2018 Projets : 3-projet - voir note / Article en page(s) : pp 383 - 399 Note générale : bibliographie
This work was performed under grant ECOCZE RB from the Università di Bologna.Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Systèmes de référence et réseaux
[Termes descripteurs IGN] International Terrestrial Reference Frame
[Termes descripteurs IGN] point de liaison (géodésie)
[Termes descripteurs IGN] positionnement par GNSS
[Termes descripteurs IGN] positionnement par télémétrie laser sur satelliteRésumé : (auteur) The realization of the international terrestrial reference frame (ITRF) is currently based on the data provided by four space geodetic techniques. The accuracy of the different technique-dependent materializations of the frame physical parameters (origin and scale) varies according to the nature of the relevant observables and to the impact of technique-specific errors. A reliable computation of the ITRF requires combining the different inputs, so that the strengths of each technique can compensate for the weaknesses of the others. This combination, however, can only be performed providing some additional information which allows tying together the independent technique networks. At present, the links used for that purpose are topometric surveys (local/terrestrial ties) available at ITRF sites hosting instruments of different techniques. In principle, a possible alternative could be offered by spacecrafts accommodating the positioning payloads of multiple geodetic techniques realizing their co-location in orbit (space ties). In this paper, the GNSS–SLR space ties on-board GPS and GLONASS satellites are thoroughly examined in the framework of global reference frame computations. The investigation focuses on the quality of the realized physical frame parameters. According to the achieved results, the space ties on-board GNSS satellites cannot, at present, substitute terrestrial ties in the computation of the ITRF. The study is completed by a series of synthetic simulations investigating the impact that substantial improvements in the volume and quality of SLR observations to GNSS satellites would have on the precision of the GNSS frame parameters. Numéro de notice : A2018-050 Affiliation des auteurs : LaSTIG LAREG+Ext (2012-mi2018) Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-017-1069-z date de publication en ligne : 06/10/2017 En ligne : https://doi.org/10.1007/s00190-017-1069-z Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=89354
in Journal of geodesy > vol 92 n° 4 (April 2018) . - pp 383 - 399[article]PermalinkPermalinkPermalinkPermalinkIGN best practice for surveying instrument reference points at ITRF co-location sites / Jean-Claude Poyard (2017)
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