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Influence of subdaily model for polar motion on the estimated GPS satellite orbits / Natalia Panafidina in Journal of geodesy, vol 93 n° 2 (February 2019)  

Public [article]  inJournal of geodesy > vol 93 n° 2 (February 2019) . - pp 229 - 240 Titre : Influence of subdaily model for polar motion on the estimated GPS satellite orbits Type de document : Article/Communication Auteurs : Natalia Panafidina, Auteur ; Urs Hugentobler, Auteur ; Manuela Seitz, Auteur Année de publication : 2019 Article en page(s) : pp 229 - 240 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie physique [Termes descripteurs IGN] analyse diachronique [Termes descripteurs IGN] élément orbital [Termes descripteurs IGN] erreur systématique [Termes descripteurs IGN] International Terrestrial Reference Frame [Termes descripteurs IGN] marée océanique [Termes descripteurs IGN] mouvement du géocentre [Termes descripteurs IGN] mouvement du pôle [Termes descripteurs IGN] orbite [Termes descripteurs IGN] positionnement par GPS [Termes descripteurs IGN] rotation de la Terre [Termes descripteurs IGN] satellite GPS [Termes descripteurs IGN] traitement du signal Résumé : (auteur) In this contribution, it is shown that GPS orbits are able to absorb some diurnal signals in polar motion. The arising implications for the influence of the subdaily pole model on GPS solutions are discussed. Two signals in polar motion can be absorbed by GPS orbits: a retrograde signal with a period of a sidereal day (23 h 56 min 4 s) and a prograde signal with a period matching the revolution period of the GPS satellites in the terrestrial reference frame (23 h 55 min 56 s). We show that the retrograde signal contributes to the absolute orientation of the orbital planes in space and the prograde signal, due to coincidence of its period with the period of revolution of the GPS satellites, contributes to the position of the geocenter for each individual satellite. It is known from previous studies that there are systematic differences between orbital parameters from GPS solutions computed with different subdaily pole models. We show in this paper that this behavior can be explained by the absorption effects in 1-day GPS orbits. Diurnal signals cannot be spectrally separated over a time interval of 1 day. Adjustment of any diurnal prograde or retrograde signal to a subdaily pole time series given by a subdaily model over 24 h will lead to an estimated signal with a nonzero amplitude. Thus, any subdaily pole model used in the processing of space geodetic observations contains a part which corresponds numerically to the discussed prograde signal and a part which corresponds to the retrograde diurnal signal. Different pole models show different amplitudes of the diurnal signals which will be absorbed by the orbits. As a result, GPS orbits computed with different subdaily pole models have systematically different orientation and position in space. Using 1-day GPS solutions over a time span of 13 years (1994–2007), we show that the systematic variations in orbit position and orientation caused by individual tidal terms in polar motion can be well predicted and explained by the suggested mechanism. Numéro de notice : A2019-080 Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-018-1153-z date de publication en ligne : 24/05/2018 En ligne : https://doi.org/10.1007/s00190-018-1153-z Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=92198 [article]

Interferometric processing of Sentinel-1 TOPS Data / Néstor Yagüe-Martínez in IEEE Transactions on geoscience and remote sensing, vol 54 n° 4 (April 2016)  

Public [article]  inIEEE Transactions on geoscience and remote sensing > vol 54 n° 4 (April 2016) . - pp 2220 - 2234 Titre : Interferometric processing of Sentinel-1 TOPS Data Type de document : Article/Communication Auteurs : Néstor Yagüe-Martínez, Auteur ; Pau Prats-Iraola, Auteur ; et al., Auteur Année de publication : 2016 Article en page(s) : pp 2220 - 2234 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Traitement d'image radar et applications [Termes descripteurs IGN] effet Doppler [Termes descripteurs IGN] élément orbital [Termes descripteurs IGN] image radar moirée [Termes descripteurs IGN] image Sentinel-SAR [Termes descripteurs IGN] Image TOPS [Termes descripteurs IGN] interféromètrie par radar à antenne synthétique [Termes descripteurs IGN] largeur de bande Résumé : (Auteur) Sentinel-1 (S-1) has an unparalleled mapping capacity. In interferometric wide swath (IW) mode, three subswaths imaged in the novel Terrain Observation by Progressive Scans (TOPS) SAR mode result in a total swath width of 250 km. S-1 has become the European workhorse for large area mapping and interferometric monitoring at medium resolution. The interferometric processing of TOPS data however requires special consideration of the signal properties, resulting from the ScanSAR-type burst imaging and the antenna beam steering in azimuth. The high Doppler rate in azimuth sets very stringent coregistration requirements, making the use of enhanced spectral diversity (ESD) necessary to obtain the required fine azimuth coregistration accuracy. Other unique aspects of processing IW data, such as azimuth spectral filtering, image resampling, and data deramping and reramping, are reviewed, giving a recipe-like description that enables the user community to use S-1 IW mode repeat-pass SAR data. Interferometric results from S-1A are provided, demonstrating the mapping capacity of the S-1 system and its interferometric suitability for geophysical applications. An interferometric evaluation of a coherent interferometric pair over Salar de Uyuni, Bolivia, is provided, where several aspects related to coregistration, deramping, and synchronization are analyzed. Additionally, a spatiotemporal evaluation of the along-track shifts, which are directly related to the orbital/instrument timing error, measured from the SAR data is shown, which justifies the necessity to refine the azimuth shifts with ESD. The spatial evaluation indicates high stability of the azimuth shifts for several slices of a datatake. Numéro de notice : A2016-841 Thématique : IMAGERIE Nature : Article nature-HAL : ArtAvecCL-RevueIntern En ligne : http://dx.doi.org/10.1109/TGRS.2015.2497902 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=82885 [article]

The impact of common versus separate estimation of orbit parameters on GRACE gravity field solutions / U. Meyer in Journal of geodesy, vol 89 n° 7 (July 2015)  

Public [article]  inJournal of geodesy > vol 89 n° 7 (July 2015) . - pp 685 - 696 Titre : The impact of common versus separate estimation of orbit parameters on GRACE gravity field solutions Type de document : Article/Communication Auteurs : U. Meyer, Auteur ; Adrian Jäggi, Auteur ; Gerhard Beutler, Auteur ; Heike Bock, Auteur Année de publication : 2015 Article en page(s) : pp 685 - 696 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie physique [Termes descripteurs IGN] données GRACE [Termes descripteurs IGN] élément orbital [Termes descripteurs IGN] orbitographie [Termes descripteurs IGN] paramètre de temps [Termes descripteurs IGN] propagation du signal [Termes descripteurs IGN] traitement du signal Résumé : (auteur) Gravity field parameters are usually determined from observations of the GRACE satellite mission together with arc-specific parameters in a generalized orbit determination process. When separating the estimation of gravity field parameters from the determination of the satellites’ orbits, correlations between orbit parameters and gravity field coefficients are ignored and the latter parameters are biased towards the a priori force model. We are thus confronted with a kind of hidden regularization. To decipher the underlying mechanisms, the Celestial Mechanics Approach is complemented by tools to modify the impact of the pseudo-stochastic arc-specific parameters on the normal equations level and to efficiently generate ensembles of solutions. By introducing a time variable a priori model and solving for hourly pseudo-stochastic accelerations, a significant reduction of noisy striping in the monthly solutions can be achieved. Setting up more frequent pseudo-stochastic parameters results in a further reduction of the noise, but also in a notable damping of the observed geophysical signals. To quantify the effect of the a priori model on the monthly solutions, the process of fixing the orbit parameters is replaced by an equivalent introduction of special pseudo-observations, i.e., by explicit regularization. The contribution of the thereby introduced a priori information is determined by a contribution analysis. The presented mechanism is valid universally. It may be used to separate any subset of parameters by pseudo-observations of a special design and to quantify the damage imposed on the solution. Numéro de notice : A2015-354 Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern En ligne : http://link.springer.com/article/10.1007/s00190-015-0807-3/fulltext.html Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=76777 [article]

Impact of the atmospheric drag on Starlette, Stella, Ajisai, and Lares Orbits / Krzysztof Sosnica in Artificial satellites, vol 50 n° 1 (March 2015)  

Public [article]  inArtificial satellites > vol 50 n° 1 (March 2015) . - pp 1 - 18 Titre : Impact of the atmospheric drag on Starlette, Stella, Ajisai, and Lares Orbits Type de document : Article/Communication Auteurs : Krzysztof Sosnica, Auteur Année de publication : 2015 Article en page(s) : pp 1 - 18 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie spatiale [Termes descripteurs IGN] élément orbital [Termes descripteurs IGN] freinage atmosphérique [Termes descripteurs IGN] orbitographie [Termes descripteurs IGN] satellite de télémétrie [Termes descripteurs IGN] télémètre laser sur satellite [Termes descripteurs IGN] télémétrie laser sur satellite Résumé : (auteur) The high-quality satellite orbits of geodetic satellites, which are determined using Satellite Laser Ranging (SLR) observations, play a crucial role in providing, e.g., low-degree coefficients of the Earth's gravity field including geocenter coordinates, Earth rotation parameters, as well as the SLR station coordinates. The appropriate modeling of non-gravitational forces is essential for the orbit determination of artificial Earth satellites. The atmospheric drag is a dominating perturbing force for satellites at low altitudes up to about 700-1000 km. This article addresses the impact of the atmospheric drag on mean semi-major axes and orbital eccentricities of geodetic spherical satellites: Starlette, Stella, AJISAI, and LARES. Atmospheric drag causes the semi-major axis decays amounting to about ▲a = -1.2, -.12, -.14, and -.30 m/year for LARES, AJISAI, Starlette, and Stella, respectively. The density of the upper atmosphere strongly depends on the solar and geomagnetic activity. The atmospheric drag affects the along-track orbit component to the largest extent, and the out-of-plane to a small extent, whereas the radial component is almost unaffected by the atmospheric drag Numéro de notice : A2015-287 Thématique : POSITIONNEMENT Nature : Article En ligne : http://www.degruyter.com/view/j/arsa.2015.50.issue-1/arsa-2015-0001/arsa-2015-00 [...] Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=76406 [article]

Orbit determination methods in view of the PODET project / Florent Deleflie (2013) 

Public contenu dans Proceedings of the annual meeting of the French Society of Astronomy & Astrophysics SF2A 2013, Montpellier, France, 4-7 juin 2013 / Luc Cambrézy (2013)   Titre : Orbit determination methods in view of the PODET project Type de document : Article/Communication Auteurs : Florent Deleflie, Auteur ; David Coulot , Auteur ; Pascal Richard, Auteur Congrès : SF2A 2013 (4 - 7 juin 2013; Montpellier, France), Auteur Editeur : Société française d'astronomie et d'astrophysique SF2A Année de publication : 2013 Importance : pp 165 - 168 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Techniques orbitales [Termes descripteurs IGN] algorithme génétique [Termes descripteurs IGN] élément orbital [Termes descripteurs IGN] orbite képlerienne [Termes descripteurs IGN] orbitographie [Termes descripteurs IGN] satellite de télémétrie Résumé : (auteur) We present an orbit determination method based on genetic algorithms. Contrary to usual estimation methods mainly based on least-squares methods, these algorithms do not require any a priori knowledge of the initial state vector to be estimated. These algorithms can be applied when a new satellite is launched or for uncatalogued objects We show in this paper preliminary results obtained from an SLR satellite, for which tracking data acquired by the ILRS network enable to build accurate orbital arcs at a few centimeter level, which can be used as a reference orbit. The method is carried out in several steps: (i) an analytical propagation of the equations of motion, (ii) an estimation kernel based on genetic algorithms, which follows the usual steps of such approaches: initialization and evolution of a selected population, so as to determine the best parameters. Each parameter to be estimated, namely each initial Keplerian element, has to be searched among an interval that is preliminary chosen. Numéro de notice : C2013-029 Thématique : POSITIONNEMENT Nature : Communication Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=80205

Documents numériques

en open access Orbit determination methods URL

Repères de référence terrestres, rotation de la terre et télémétrie laser sur satellites / David Coulot in Géomatique expert, n° 50 (01/05/2006)

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GPS : Theory, algorithms and applications / Guochang Xu (2003)

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Modeling and validating orbits and clocks using the Global Positioning System / Tim A. Springer (2000)  

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Determining the GPS orbit with the dynamic collocation model / L. Quanwei (1996)

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Description mathématique de la chaine : estimation de paramètres et analyse d'erreur, 1. Vol 1 / J. Bardina (1989)

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Extensions de la théorie de Kaula aux fonctions perturbatrices luni-solaires et de marées / Pierre Exertier (1989)

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GPS - network analysis / Wojciech Pachelski (1988)

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Summary of discussion for the splinter session on "Orbit selection" of the Topex-Poseidon SDT meeting, Paris, 6 - 8 May, 1988 / J.F. Minster (1988)

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An operational method using Argos orbital elements for navigation of AVHRR imagery / P. Brunel in International Journal of Remote Sensing IJRS, vol 8 n° 4 (April 1987)

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A contribution to 3D-operational geodesy, Part 4. The observation equations of satellite geodesy in the model of integrated geodesy / Bernd Eissfeller (1986)

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