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Broadcast ephemerides for LEO augmentation satellites based on nonsingular elements / Lingdong Meng in GPS solutions, vol 25 n° 4 (October 2021)  

Public [article]  inGPS solutions > vol 25 n° 4 (October 2021) . - n° 129 Titre : Broadcast ephemerides for LEO augmentation satellites based on nonsingular elements Type de document : Article/Communication Auteurs : Lingdong Meng, Auteur ; Junping Chen, Auteur ; Jiexian Wang, Auteur ; et al., Auteur Année de publication : 2021 Article en page(s) : n° 129 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Techniques orbitales [Termes IGN] élément orbital [Termes IGN] éphémérides de satellite [Termes IGN] modèle d'orbite [Termes IGN] mouvement Képlerien [Termes IGN] orbite basse [Termes IGN] orbitographie Résumé : (auteur) Low earth orbit (LEO) satellite constellations have the potential to augment global navigation satellite system services. Among the ongoing tasks of LEO-based navigation, providing broadcast ephemerides that satisfy the accuracy requirement for positioning, navigation, and timing is one of the most critical prerequisites. Singularities can occur when fitting broadcast ephemeris parameters in the case of a small eccentricity or small or large inclination. We choose an improved nonsingular element set for the LEO broadcast ephemeris design. We establish suitable broadcast ephemeris models, considering the fit accuracy, number of parameters, orbital altitude, and inclination. The fit accuracy using different orbital altitudes, orbital inclinations, and eccentricities suggests that the optimal parameters are n˙, n¨, Crc3, Crs3, Cλc3, and Cλs3, together with the basic broadcast ephemeris model. After adding these six parameters, a fit accuracy of better than 10 cm can be achieved with a 20 min arc length and 500–1400 km orbital altitudes. The effects of the number of parameters, orbital altitude, inclination, and eccentricity on the fit accuracy are discussed in detail. Finally, the performance is validated with real LEO satellites to confirm the effectiveness of the proposed method. Numéro de notice : A2021-566 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s10291-021-01162-7 date de publication en ligne : 22/07/2021 En ligne : https://doi.org/10.1007/s10291-021-01162-7 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=98135 [article]

POD of small LEO satellites based on precise real-time MADOCA and SBAS-aided PPP corrections / Amir Allahvirdi-Zadeh in GPS solutions, vol 25 n° 2 (April 2021)  

Public [article]  inGPS solutions > vol 25 n° 2 (April 2021) . - 14 p. Titre : POD of small LEO satellites based on precise real-time MADOCA and SBAS-aided PPP corrections Type de document : Article/Communication Auteurs : Amir Allahvirdi-Zadeh, Auteur ; Kan Wang, Auteur ; Ahmed El-Mowafy, Auteur Année de publication : 2021 Article en page(s) : 14 p. Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Techniques orbitales [Termes IGN] données GNSS [Termes IGN] horloge du satellite [Termes IGN] orbite basse [Termes IGN] orbitographie par GNSS [Termes IGN] positionnement ponctuel précis [Termes IGN] temps réel Résumé : (Auteur) For real-time precise orbit determination (POD) of low earth orbit (LEO) satellites, high-accuracy global navigation satellite system (GNSS) orbit and clock products are necessary in real time. Recently, the Japanese multi-GNSS advanced demonstration of orbit and clock analysis precise point positioning (PPP) service and the new generation of the Australian/New Zealand satellite-based augmentation system (SBAS)-aided PPP service provide free and precise GNSS products that are directly broadcast through the navigation and geostationary earth orbit satellites, respectively. With the high quality of both products shown in this study, a 3D accuracy of centimeters can be achieved in the post-processing mode for the reduced-dynamic orbits of small LEO satellites having a duty cycle down to 40% and at sub-dm to dm level for the kinematic orbits. The results show a promising future for high-accuracy real-time POD onboard LEO satellites benefiting from the precise free-of-charge PPP corrections broadcast by navigation systems or SBAS. Numéro de notice : A2021-091 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s10291-020-01078-8 date de publication en ligne : 11/01/2021 En ligne : https://doi.org/10.1007/s10291-020-01078-8 Format de la ressource électronique : URL Article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=96880 [article]

Determination of precise Galileo orbits using combined GNSS and SLR observations / Grzegorz Bury in GPS solutions, vol 25 n° 1 (January 2021)  

Public [article]  inGPS solutions > vol 25 n° 1 (January 2021) . - n° 11 Titre : Determination of precise Galileo orbits using combined GNSS and SLR observations Type de document : Article/Communication Auteurs : Grzegorz Bury, Auteur ; Krzysztof Sosnica, Auteur ; Radoslaw Zajdel, Auteur ; et al., Auteur Année de publication : 2021 Article en page(s) : n° 11 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Techniques orbitales [Termes IGN] données GNSS [Termes IGN] données TLS (télémétrie) [Termes IGN] Galileo [Termes IGN] International Terrestrial Reference Frame [Termes IGN] orbite précise [Termes IGN] orbitographie [Termes IGN] pondération Résumé : (auteur) Galileo satellites are equipped with laser retroreflector arrays for satellite laser ranging (SLR). In this study, we develop a methodology for the GNSS-SLR combination at the normal equation level with three different weighting strategies and evaluate the impact of laser observations on the determined Galileo orbits. We provide the optimum weighting scheme for precise orbit determination employing the co-location onboard Galileo. The combined GNSS-SLR solution diminishes the semimajor axis formal error by up to 62%, as well as reduces the dependency between values of formal errors and the elevation of the Sun above the orbital plane—the β angle. In the combined solution, the standard deviation of the SLR residuals decreases from 36.1 to 29.6 mm for Galileo-IOV satellites and |β|> 60°, when compared to GNSS-only solutions. Moreover, the bias of the Length-of-Day parameter is 20% lower for the combined solution when compared to the microwave one. As a result, the combination of GNSS and SLR observations provides promising results for future co-locations onboard the Galileo satellites for the orbit determination, realization of the terrestrial reference frames, and deriving geodetic parameters. Numéro de notice : A2021-008 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s10291-020-01045-3 date de publication en ligne : 31/10/2020 En ligne : https://doi.org/10.1007/s10291-020-01045-3 Format de la ressource électronique : url article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=96298 [article]

Integrated processing of ground- and space-based GPS observations: improving GPS satellite orbits observed with sparse ground networks / Wen Huang in Journal of geodesy, vol 94 n° 10 (October 2020)  

Public [article]  inJournal of geodesy > vol 94 n° 10 (October 2020) . - 13 p. Titre : Integrated processing of ground- and space-based GPS observations: improving GPS satellite orbits observed with sparse ground networks Type de document : Article/Communication Auteurs : Wen Huang, Auteur ; Benjamin Männel, Auteur ; Pierre Sakic-Kieffer, Auteur ; et al., Auteur Année de publication : 2020 Article en page(s) : 13 p. Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Techniques orbitales [Termes IGN] modèle d'orbite [Termes IGN] orbite basse [Termes IGN] orbite précise [Termes IGN] orbitographie [Termes IGN] orbitographie par GNSS [Termes IGN] récepteur GPS [Termes IGN] station GPS Résumé : (auteur) The precise orbit determination (POD) of Global Navigation Satellite System (GNSS) satellites and low Earth orbiters (LEOs) are usually performed independently. It is a potential way to improve the GNSS orbits by integrating LEOs onboard observations into the processing, especially for the developing GNSS, e.g., Galileo with a sparse sensor station network and Beidou with a regional distributed operating network. In recent years, few studies combined the processing of ground- and space-based GNSS observations. The integrated POD of GPS satellites and seven LEOs, including GRACE-A/B, OSTM/Jason-2, Jason-3 and, Swarm-A/B/C, is discussed in this study. GPS code and phase observations obtained by onboard GPS receivers of LEOs and ground-based receivers of the International GNSS Service (IGS) tracking network are used together in one least-squares adjustment. The POD solutions of the integrated processing with different subsets of LEOs and ground stations are analyzed in detail. The derived GPS satellite orbits are validated by comparing with the official IGS products and internal comparison based on the differences of overlapping orbits and satellite positions at the day-boundary epoch. The differences between the GPS satellite orbits derived based on a 26-station network and the official IGS products decrease from 37.5 to 23.9 mm (34% improvement) in 1D-mean RMS when adding seven LEOs. Both the number of the space-based observations and the LEO orbit geometry affect the GPS satellite orbits derived in the integrated processing. In this study, the latter one is proved to be more critical. By including three LEOs in three different orbital planes, the GPS satellite orbits improve more than from adding seven well-selected additional stations to the network. Experiments with a ten-station and regional network show an improvement of the GPS satellite orbits from about 25 cm to less than five centimeters in 1D-mean RMS after integrating the seven LEOs. Numéro de notice : A2020-630 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-020-01424-1 date de publication en ligne : 10/10/2020 En ligne : https://doi.org/10.1007/s00190-020-01424-1 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=96049 [article]

Impact of thermospheric mass density on the orbit prediction of LEO satellites / Changyong He in Space weather, vol 18 n° 1 (January 2020)  

Public [article]  inSpace weather > vol 18 n° 1 (January 2020) . - n° e2019SW002336 Titre : Impact of thermospheric mass density on the orbit prediction of LEO satellites Type de document : Article/Communication Auteurs : Changyong He , Auteur ; Yang Yang, Auteur ; Brett Anthony Carter, Auteur ; Kefei Zhang, Auteur ; Andong Hu, Auteur ; Wang Li, Auteur ; Florent Deleflie, Auteur ; Robert Norman, Auteur ; Suqin Wu, Auteur Année de publication : 2020 Projets : 1-Pas de projet / Article en page(s) : n° e2019SW002336 Note générale : bibliographie This study was supported by the Cooperative Research Centre for Space Environment Management (SERCLimited) through the Australian Government's Cooperative Research Centre Programme and partially supported by the National Natural Science Foundation of China (41874040) and the CUMT Independent Innovation Project of “Double-First Class” Construction (2018ZZCX08) Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Techniques orbitales [Termes IGN] masse d'air [Termes IGN] orbite basse [Termes IGN] orbitographie Résumé : (auteur) Many thermospheric mass density (TMD) variations have been recognized in observations and physical simulations; however, their impact on the low‐Earth‐orbit satellites has not been fully evaluated. The present study investigates the quantitative impact of periodic spatiotemporal TMD variations modulated by the empirical DTM2013 model. Also considered are two small‐scale variations, that is, the equatorial mass anomaly and the midnight density maximum, which are reproduced by the Thermosphere‐Ionosphere‐Electrodynamics General Circulation Model. This investigation is performed through a 1‐day orbit prediction (OP) simulation for a 400‐km circular orbit. The results show that the impact of TMD variations during solar maximum is 1 order of magnitude larger than that during solar minimum. The dominant impact has been found in the along‐track direction. Semiannual and semidiurnal variations in TMD exert the most significant impact on OP among the intra‐annual and intradiurnal variations, respectively. The zero mean periodic variations in TMD may not significantly affect the predicted orbit but increase the orbital uncertainty if their periods are shorter than the time span of OP. Additionally, the equatorial mass anomaly creates a mean orbit difference of 50 m (5 m) with a standard deviation of 30 m (3 m) in 1‐day OP during high (low) solar activity. The midnight density maximum exhibits a stronger impact in the order of 150±30 and 15±6 m during solar maximum and solar minimum, respectively. This study makes clear that careful selection of TMD variations is of great importance to balance the trade‐off between efficiency and accuracy in OP problems. Numéro de notice : A2020-467 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1029/2019SW002336 date de publication en ligne : 06/11/2019 En ligne : https://doi.org/10.1029/2019SW002336 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=95553 [article]

Precise orbit determination of the Sentinel-3A altimetry satellite using ambiguity-fixed GPS carrier phase observations / Olivier Montenbruck in Journal of geodesy, vol 92 n° 7 (July 2018)  

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Estimation of antenna phase center offset for BDS IGSO and MEO satellites / Guanwen Huang in GPS solutions, vol 22 n° 2 (April 2018)  

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Self-shadowing of a spacecraft in the computation of surface forces : An example in planetary geodesy / Georges Balmino in Artificial satellites, vol 53 n° 1 (March 2018)  

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Validation of Galileo orbits using SLR with a focus on satellites launched into incorrect orbital planes / Krzysztof Sosnica in Journal of geodesy, vol 92 n° 2 (February 2018)  

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Benefits of satellite clock modeling in BDS and Galileo orbit determination / Yun Qing in Advances in space research, vol 60 n° 12 (15 December 2017)  

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Precise orbit determination of the Fengyun-3C satellite using onboard GPS and BDS observations / Min Li in Journal of geodesy, vol 91 n° 11 (November 2017)  

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Precision on board : orbit determination of LEO satellites with real-time corrections / André Hauschild in GPS world, vol 28 n° 4 (April 2017)

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Precise orbit determination based on raw GPS measurements / Norbert Zehentner in Journal of geodesy, vol 90 n° 3 (March 2016)  

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Estimating the yaw-attitude of an BDS IGSO and MEO satellites / Xiaolei Dai in Journal of geodesy, vol 89 n° 10 (october 2015)  

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Application d'algorithmes génétiques à la détermination d'orbites optimales pour GRASP / Arnaud Pollet in XYZ, n° 144 (septembre - novembre 2015)

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