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Precise onboard time synchronization for LEO satellites / Florian Kunzi in Navigation : journal of the Institute of navigation, vol 69 n° 3 (Fall 2022)  

Public [article]  inNavigation : journal of the Institute of navigation > vol 69 n° 3 (Fall 2022) . - n° 531 Titre : Precise onboard time synchronization for LEO satellites Type de document : Article/Communication Auteurs : Florian Kunzi, Auteur ; Oliver Montenbruck, Auteur Année de publication : 2022 Article en page(s) : n° 531 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Techniques orbitales [Termes IGN] données GNSS [Termes IGN] horloge [Termes IGN] orbite basse [Termes IGN] orbitographie [Termes IGN] oscillateur [Termes IGN] récepteur DORIS [Termes IGN] récepteur GNSS [Termes IGN] récepteur trifréquence [Termes IGN] synchronisation [Termes IGN] temps réel Résumé : (auteur) Onboard time synchronization is an important requirement for a wide range of low Earth orbit (LEO) missions such as altimetry or communication services, and extends to future position, navigation, and timing (PNT) services in LEO. For GNSS-based time synchronization, continuous knowledge about the satellite’s position is required and, eventually, the quality of the position solution defines the timing precision attainable through GNSS measurements. Previous research has shown that real-time GNSS orbit determination of LEO satellites can achieve decimeter-level accuracy. This paper characterizes the performance of GNSS-based real-time clock synchronization in LEO using the satellite Sentinel-6A as a real-world case study. The satellite’s ultra-stable oscillator (USO) and triple-frequency GPS/Galileo receiver provide measurements for a navigation filter representative of real-time onboard processing. Continuous evaluation of actual flight data over 14 days shows that a 3D orbit root-mean-square (RMS) error of 11 cm and a 0.9-ns clock standard deviation can be achieved. Numéro de notice : A2022-822 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article DOI : 10.33012/navi.531 Date de publication en ligne : 12/04/2022 En ligne : https://doi.org/10.33012/navi.531 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=101991 [article]

Inclusion of GPS clock estimates for satellites Sentinel-3A/3B in DORIS geodetic solutions / Petr Štěpánek in Journal of geodesy, vol 94 n° 12 (December 2020)  

Public [article]  inJournal of geodesy > vol 94 n° 12 (December 2020) . - n° 116 Titre : Inclusion of GPS clock estimates for satellites Sentinel-3A/3B in DORIS geodetic solutions Type de document : Article/Communication Auteurs : Petr Štěpánek, Auteur ; Duan Bingbing, Auteur ; Filler Vratislav, Auteur ; et al., Auteur Année de publication : 2020 Article en page(s) : n° 116 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie spatiale [Termes IGN] Atlantique Sud [Termes IGN] Cryosat [Termes IGN] décalage d'horloge [Termes IGN] données DORIS [Termes IGN] horloge du récepteur [Termes IGN] Jason [Termes IGN] oscillateur [Termes IGN] récepteur DORIS [Termes IGN] récepteur GPS [Termes IGN] rotation de la Terre [Termes IGN] SARAL [Termes IGN] Sentinel-3 Résumé : (auteur) A unique architecture of Sentinel-3A and Sentinel-3B satellites includes the shared ultra-stable oscillator (USO) by the DORIS and GPS receivers. This concept enables to apply onboard GPS clock estimates in the DORIS processing substituting the DORIS polynomial clock model by the GPS epoch-wise model, together with a DORIS-specific clock offset. Such an approach is particularly profitable for the mitigation of the South Atlantic Anomaly (SAA) effect affecting the short-term frequency stability of the USO oscillator in the South America and South Atlantic region. The GPS clock behavior precisely maps the SAA effect and enables us to demonstrate a difference of the USO sensitivity to the SAA for Sentinel-3A and Sentinel-3B. We present world grid maps of clock time derivatives for both Sentinels, displaying a different sign of the direct effect and other differences in the USO memory/recovery effect. Moreover, we present the impact of SAA on 3D positioning where the largest SAA-related bias reaches several centimeters. We also determine an effect of the precise clock modeling on the Earth rotation parameter estimates. In addition to these improvements, the elimination of the SAA effect gives us an opportunity to get an almost SAA-free DORIS solution from Sentinel-3A and Sentinel-3B satellites. Using the combined solution of both Sentinels as a reference, we estimate the SAA effect on the DORIS beacon positions also for satellites Jason-2, Jason-3, Saral, Cryosat-2 and Hy-2A and find significant positioning biases for all the recent satellites except Saral. Numéro de notice : A2020-737 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-020-01428-x Date de publication en ligne : 18/11/2020 En ligne : https://doi.org/10.1007/s00190-020-01428-x Format de la ressource électronique : url article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=96353 [article]

The Cryosat system: the satellite and its altimeter / G. Ratier in ESA bulletin, n° 122 (May 2005)  

Public [article]  inESA bulletin > n° 122 (May 2005) . - pp 19 - 26 Titre : The Cryosat system: the satellite and its altimeter Type de document : Article/Communication Auteurs : G. Ratier, Auteur ; R. Francis, Auteur ; et al., Auteur Année de publication : 2005 Article en page(s) : pp 19 - 26 Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Technologies spatiales [Termes IGN] altimètre radar [Termes IGN] charge utile [Termes IGN] Cryosat [Termes IGN] récepteur DORIS [Termes IGN] SAR and interferometric radar altimeter [Termes IGN] satellite d'observation de la Terre Résumé : (Auteur) In the preceding article (A05275), Prof. Duncan Wingham has outlined the genesis of CryoSat, its scientific objectives and its programmatic constraints. The mission objectives are characterised by the determination of small height-related changes over a three-year period. This imposes requirements on the type of measurements to be made, the physical stability of the system, control of the measurement configuration and consistency in the data processing system. The programmatic constraints on the other hand, may be simply characterised as the need for a relatively short development cycle with a stringent cost ceiling. CryoSat is a fully integrated system in which all of the elements have been developed together within the programme to ensure the control needed to satisfy the mission objectives. However, in the interests of readability, the system's description has been split over two articles : this one describing the elements that are to be launched into space, and the following one those parts that will remain on Earth. Numéro de notice : A2005-276 Affiliation des auteurs : non IGN Thématique : IMAGERIE/POSITIONNEMENT Nature : Article DOI : sans En ligne : http://www.esa.int/esapub/bulletin/bulletin122/bul122c_ratier.pdf Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=27412 [article]

Doris satellite antenna maps derived from long-term residuals time series / Pascal Willis in Advances in space research, vol 36 n° 3 (March 2005)  

Public [article]  inAdvances in space research > vol 36 n° 3 (March 2005) . - pp 486 - 497 Titre : Doris satellite antenna maps derived from long-term residuals time series Type de document : Article/Communication Auteurs : Pascal Willis , Auteur ; Shailen Desai, Auteur ; Willy I. Bertiger, Auteur ; Bruce J. Haines, Auteur ; Albert Auriol, Auteur Année de publication : 2005 Article en page(s) : pp 486 - 497 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie spatiale [Termes IGN] balise DORIS [Termes IGN] DORIS [Termes IGN] orbitographie [Termes IGN] phase [Termes IGN] récepteur DORIS [Termes IGN] série temporelle [Termes IGN] trajet multiple Résumé : (Auteur) Recent studies have shown that phase pattern models for the Jason1 GPS antenna significantly benefit GPSbased precise orbit determination (POD) for the satellite. We have used a similar technique to derive DORIS receiver antenna maps, using all available DORIS tracking data over long time periods (from 1993.0 to 2004.0). We demonstrate that the derived correction models are satellite specific. For a given satellite, yeartoyear estimations show clear systematic patterns. Some of these systematic patterns are attributable to the derivative of the multipath effects in the direction of the satellite velocity. For early SPOT data, the patterns can be explained by an offset in the TAI time tagging (typically 8 us). In a second step, we have applied the SPOT2 antenna correction models in precise orbit determination and in the positioning of ground beacons. Preliminary results on DORIS/SPOT2 show that application of the DORIS antenna maps lead to a slight improvement of the derived POD and geodetic results (typically less than 5%). Numéro de notice : A2005-603 Affiliation des auteurs : IGN+Ext (1940-2011) Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1016/j.asr.2005.03.095 Date de publication en ligne : 06/05/2005 En ligne : https://doi.org/10.1016/j.asr.2005.03.095 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=33946 [article]

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Topex-Jason combined GPS-DORIS orbit determination in the TanDEM phase / Pascal Willis in Advances in space research, vol 31 n° 8 (14/03/2003)  

Public [article]  inAdvances in space research > vol 31 n° 8 (14/03/2003) . - pp 1941 - 1946 Titre : Topex-Jason combined GPS-DORIS orbit determination in the TanDEM phase Type de document : Article/Communication Auteurs : Pascal Willis , Auteur ; Bruce J. Haines, Auteur ; Yoaz E. Bar-Sever, Auteur ; Willy I. Bertiger, Auteur ; R. Muellerschoen, Auteur ; Da Kuang, Auteur ; Shailen Desai, Auteur Année de publication : 2003 Article en page(s) : pp 1941 - 1946 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Techniques orbitales [Termes IGN] balise DORIS [Termes IGN] GIPSY-OASIS [Termes IGN] Jason [Termes IGN] orbite précise [Termes IGN] orbitographie [Termes IGN] récepteur DORIS [Termes IGN] récepteur GPS [Termes IGN] TOPEX-Poseidon Résumé : (Auteur) In December 2001, the Jason-1 satellite was launched to extend the long-term success of the TOPEX/POSEIDON (T/P) oceanographic mission. The goals for the Jason-1 mission represent both a significant challenge and a rare opportunity for precise orbit determination (POD) analysts. Like its predecessor, Jason-1 carries three types of POD systems: a GPS receiver, a DORIS receiver and a laser retro-reflector. In view of the 1-cm goal for radial orbit accuracy, several major improvements have been made to the POD systems: 1) the GPS "BlackJack" TurboRogue Space Receiver (TRSR) tracks up to 12 GPS spacecraft using advanced codeless tracking techniques; 2) a newly developed DORIS receiver can track two ground beacons simultaneously with lower noise. In addition, the satellite itself features more straightforward attitude behavior, and a symmetric shape, simplifying the orbit determination models compared to T/P. On the other hand, the area-to-mass ratio for Jason-1 is larger, implying larger potential surface-force errors. This paper presents Jason-1 POD results obtained at JPL using the GIPSYOASIS II (GOA) software package. Results from standard tests (orbit overlaps, laser control points) suggest that 1 to 2 cm radial orbit precision is already being achieved using the JPL reduced-dynamic estimation approach. We also report new DORIS POD strategies that make full profit of the additional number of common DORIS observations due to the T/P-Jason-1 tandem mode of orbit as well the additional dual-channel capability of the upgraded JASON receiver (allowing simultaneous tracking of two ground stations). New information on the satellite's time scale is availed through this new estimation strategy. Results show that a significant improvement to DORIS-based orbits could be gained using this strategy. Building on these results, we have extended the GIPSY/OASIS II software capability to more fully exploit the combined benefit of both GPS and DORIS measurements from UP and Jason-1 in their preliminary tandem mode. POD test results are used to demonstrate the accuracy of these orbits and to compare results in different cases: DORIS-alone, and GPS and DORIS together in both single- and multi-satellite modes. On the other, we have demonstrated and explained an anomalous behavior of the on-board oscillator when crossing the South Atlantic Anomaly region. Finally, plans for future software enhancements, processing strategies and modeling improvements are presented. Numéro de notice : 54856 Affiliation des auteurs : IGN+Ext (1940-2011) Thématique : IMAGERIE/POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1016/S0273-1177(03)00156-X Date de publication en ligne : 28/10/2003 En ligne : https://doi.org/10.1016/S0273-1177(03)00156-X Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=34308 [article]

SPOT 5 / Centre national d'études spatiales (2002)

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Modélisation et estimation du frottement atmosphérique sur les satellites Spot2 et Spot3 dans le cadre du système DORIS / R. Garmier (2001)

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Positionnement précis et tectonique des plaques à partir du système spatial Doris / Laurent Soudarin (1995)

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Localisation géodésique à l'aide du système Doris / Jean-Philippe Dufour (04/02/1992)

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DORIS/Poseidon / Muriel Gavoret (1991)

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Synthèse des résultats de localisation Doris après sept mois de mission Doris sur SPOT 2 / Claude Boucher (1990)

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DORIS, Détermination d'Orbite et Radiopositionnement Intégrés par Satellite / M. Dorrer (10/06/1987)

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Positioning accuracy of the DORIS, SPOT 2 system / N. De Moegen (04/11/1985)

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Revue de définition DORIS / Maurice Lefebvre (1983)

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Description du système de localisation précise Doris / Jean-Philippe Dufour (1980)

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