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Characteristics of the BDS-3 multipath effect and mitigation methods using precise point positioning / Ran Lu in GPS solutions, vol 26 n° 2 (April 2022)  

Public [article]  inGPS solutions > vol 26 n° 2 (April 2022) . - n° 41 Titre : Characteristics of the BDS-3 multipath effect and mitigation methods using precise point positioning Type de document : Article/Communication Auteurs : Ran Lu, Auteur ; Wen Chen, Auteur ; Chenglong Zhang, Auteur ; et al., Auteur Année de publication : 2022 Article en page(s) : n° 41 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie spatiale [Termes IGN] constellation BeiDou [Termes IGN] correction du trajet multiple [Termes IGN] modèle stochastique [Termes IGN] orbite géostationnaire [Termes IGN] orbite terrestre [Termes IGN] positionnement par BeiDou [Termes IGN] positionnement ponctuel précis [Termes IGN] répétabilité [Termes IGN] trajet multiple Résumé : (auteur) Multipath effect is one of the main challenges of precise point positioning (PPP) in complex environments. Nowadays, the BeiDou global navigation satellite system (BDS-3) constellation was fully operational. We evaluated the multipath characteristics of BDS-3 open-service signals. The results indicate that the B2a signal had the best anti-multipath performance, and B1C signal had the worst capability. Since BDS-3 satellites with different orbital types have different orbital repeat time, the traditional method based on multipath time-domain repeatability is complicated to alleviate the multipath error on BDS-3 satellites. In contrast, the multipath spatial-domain repeatability method does not need to calculate the orbital repeat times and is only related to the position of the satellite in the sky. It has the advantages of simple algorithm and easy implementation. We selected a multipath hemispherical map (MHM) and a MHM based on trend-surface analysis (T-MHM) to evaluate the effects of BDS-3 PPP multipath correction. The positioning results for the inclined geosynchronous orbit (IGSO) and medium earth orbit (MEO) satellites, which were separately modeled and corrected, are slightly better than those obtained when they were modeled and corrected together. Compared with the uncorrected multipath, the positioning accuracy of B1I/B3I and B1C/B2a ionospheric-free (IF) combinations using the MHM can be improved by 52.7% and 51.6% and the convergence time can be shortened by 48.6% and 57.5%, respectively. The positioning accuracy of B1I/B3I and B1C/B2a IF combinations using the T-MHM can be improved by 67% and 66.9% and the convergence time can be shortened by 69.3% and 76.5%, respectively. The T-MHM introduces trend-surface analysis to model the spatial variation of the multipath inside the grid, which effectively alleviates high-frequency and low-frequency multipath. This study is of great significance for further improvements to the application of BDS-3 in complex environments. Numéro de notice : A2022-106 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article DOI : 10.1007/s10291-022-01227-1 Date de publication en ligne : 24/01/2022 En ligne : https://doi.org/10.1007/s10291-022-01227-1 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=99606 [article]

On-orbit BDS signals and transmit antenna gain analysis for a geostationary satellite / Meng Wang in Advances in space research, vol 69 n° 7 (April 2022)  

Public [article]  inAdvances in space research > vol 69 n° 7 (April 2022) . - pp 2711 - 2723 Titre : On-orbit BDS signals and transmit antenna gain analysis for a geostationary satellite Type de document : Article/Communication Auteurs : Meng Wang, Auteur ; Tao Shan, Auteur ; Lei Liu, Auteur ; et al., Auteur Année de publication : 2022 Article en page(s) : pp 2711 - 2723 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Techniques orbitales [Termes IGN] affaiblissement de la précision [Termes IGN] orbite géostationnaire [Termes IGN] orbite terrestre [Termes IGN] orbitographie [Termes IGN] récepteur BeiDou [Termes IGN] satellite géostationnaire [Termes IGN] signal BeiDou Résumé : (auteur) A Beidou navigation satellite system (BDS) receiver with high sensitivity is embarked in a geostationary orbit (GEO) spacecraft to demonstrate characteristics of BDS signals tracked. This receiver can be compatible with the regional (BDS-2) and global (BDS-3) systems, which have three orbit types: medium Earth orbit (MEO), inclined geostationary orbit (IGSO), and GEO. The on-orbit BDS signal characteristics, including observations quantity, availability, position dilution of precision (PDOP), and carrier-to-noise ratio (C/N0), are presented according to in-flight data. The observations and distribution of C/N0 with respect to nadir angles were analyzed. The average number of the BDS satellites tracked is 4.4, and the average PDOP is 12.0. PDOP improves when the BDS GEO and IGSO observations are involved. The maximum value of C/N0 of the BDS-3 MEO satellites is approximately 49 dB-Hz, which is roughly 2 dB higher than that of the BDS-2 MEO satellites. Most of the C/N0 of the BDS-3 MEO satellite at nadir angles beyond 26° is in the range of 27–34 dB-Hz. We reconstruct the transmit antenna gain for all observed BDS satellites using C/N0 measurements. Moreover, we investigate the main and side lobe characteristics of the BDS satellites in terms of different orbit types and satellite manufacturers. The side lobe signals of the BDS-3 MEO generally have 20–30 dB lower gain than the peak main lobe gain. The side lobe signal performance of the BDS-2 MEO is evidently better than that of the BDS-3 MEO. We give side lobe characteristics analysis of the BDS-3 MEO satellites from two different manufacturers based on the transmit antenna gain reconstructed. Numéro de notice : A2022-230 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article DOI : 10.1016/j.asr.2022.01.022 Date de publication en ligne : 25/01/2022 En ligne : https://doi.org/10.1016/j.asr.2022.01.022 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=100107 [article]

Reference system origin and scale realization within the future GNSS constellation “Kepler” / Susanne Glaser in Journal of geodesy, vol 94 n° 12 (December 2020)  

Public [article]  inJournal of geodesy > vol 94 n° 12 (December 2020) . - n° 117 Titre : Reference system origin and scale realization within the future GNSS constellation “Kepler” Type de document : Article/Communication Auteurs : Susanne Glaser, Auteur ; Grzegorz Michalak, Auteur ; Benjamin Männel, Auteur ; et al., Auteur Année de publication : 2020 Article en page(s) : n° 117 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie spatiale [Termes IGN] centre de phase [Termes IGN] constellation Galileo [Termes IGN] constellation GNSS [Termes IGN] décorrélation [Termes IGN] géocentre [Termes IGN] International Terrestrial Reference Frame [Termes IGN] Kepler, Johannes [Termes IGN] orbite basse [Termes IGN] orbite terrestre [Termes IGN] orbitographie Résumé : (auteur) Currently, Global Navigation Satellite Systems (GNSS) do not contribute to the realization of origin and scale of combined global terrestrial reference frame (TRF) solutions due to present system design limitations. The future Galileo-like medium Earth orbit (MEO) constellation, called “Kepler”, proposed by the German Aerospace Center DLR, is characterized by a low Earth orbit (LEO) segment and the innovative key features of optical inter-satellite links (ISL) delivering highly precise range measurements and of optical frequency references enabling a perfect time synchronization within the complete constellation. In this study, the potential improvements of the Kepler constellation on the TRF origin and scale are assessed by simulations. The fully developed Kepler system allows significant improvements of the geocenter estimates (realized TRF origin in long-term). In particular, we find improvements by factors of 43 for the Z and of 8 for the X and Y component w. r. t. a contemporary MEO-only constellation. Furthermore, the Kepler constellation increases the reliability due to a complete de-correlation of the geocenter coordinates and the orbit parameters related to the solar radiation pressure modeling (SRP). However, biases in SRP modeling cause biased geocenter estimates and the ISL of Kepler can only partly compensate this effect. The realized scale enabling all Kepler features improves by 34% w. r. t. MEO-only. The dependency of the estimated satellite antenna phase center offsets (PCOs) upon the underlying TRF impedes a scale realization by GNSS. In order to realize the network scale with 1 mm accuracy, the PCOs have to be known within 2 cm for the MEO and 4 mm for the LEO satellites. Independently, the scale can be realized by estimating the MEO PCOs and by simultaneously fixing the LEO PCOs. This requires very accurate LEO PCOs; the simulations suggest them to be smaller than 1 mm in order to keep scale changes below 1 mm. Numéro de notice : A2020-736 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-020-01441-0 Date de publication en ligne : 19/11/2020 En ligne : https://doi.org/1https://doi.org/10.1007/s00190-020-01441-0 Format de la ressource électronique : url article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=96352 [article]

Orbit and clock analysis of BDS-3 satellites using inter-satellite link observations / Xin Xie in Journal of geodesy, vol 94 n° 7 (July 2020)  

Public [article]  inJournal of geodesy > vol 94 n° 7 (July 2020) . - n° 64 Titre : Orbit and clock analysis of BDS-3 satellites using inter-satellite link observations Type de document : Article/Communication Auteurs : Xin Xie, Auteur ; Tao Geng, Auteur ; Qile Zhao, Auteur ; et al., Auteur Année de publication : 2020 Article en page(s) : n° 64 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie spatiale [Termes IGN] constellation BeiDou [Termes IGN] horloge du satellite [Termes IGN] orbite géostationnaire [Termes IGN] orbite terrestre [Termes IGN] orbitographie [Termes IGN] variance d'Allan Résumé : (auteur) China is currently focusing on the establishment of its BDS-3 system, and a BDS-3 constellation with 18 satellites in medium Earth orbit (MEO) and one satellite in geostationary Earth orbit (GEO) has been able to provide preliminary global services since the end of 2018. These BDS-3 satellites feature the inter-satellite link (ISL) and new high-quality onboard clocks. In this study, we present the analysis of BDS-3 orbits and clocks determined by Ka-band ISL measurements from 18 MEO satellites and one GEO satellite. The ISL data of 43 days from 1 January to 12 February 2019 are used. The BDS-3 ISL measurement is described by a dual one-way ranging model. After converting bidirectional observations to the same epoch, Ka-band clock-free and geometry-free observables are obtained by the addition and subtraction of dual one-way observations, respectively. One anchor station with Ka-band bidirectional observations is introduced into the orbit determination to provide the orientation constraints. Using Ka-band clock-free observables, BDS-3 satellite orbits are determined. The ISL hardware delays are estimated together with orbits, and the resulting hardware delay estimates are quite stable with STD of about 0.03 ns. The Ka-band orbits are evaluated by orbit overlap differences, comparison with L-band precise orbits, and satellite laser ranging validation. The results indicate that the radial orbit errors are on the 2–4 cm level for MEO satellites and 8–10 cm for the GEO satellite. In addition, we investigate the ground anchoring capability by adding one anchor station and reducing the amount of data of the anchor station. Using Ka-band geometry-free observables, BDS-3 satellite clocks are estimated and the RMS of post-fit ISL residuals is about 5 cm. The Ka-band clock offsets are analyzed and compared with L-band precise clocks. Independent of orbit errors, the Allan deviation of Ka-band clocks for averaging interval longer than 5000 s is superior to that of L-band clocks. Furthermore, a pronounced bump, which appears in the Allan deviation of L-band clocks, almost vanishes in Ka-band clocks. Finally, the periodic variations are detected for L-band and Ka-band clocks. Numéro de notice : A2020-534 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-020-01394-4 Date de publication en ligne : 08/07/2020 En ligne : https://doi.org/10.1007/s00190-020-01394-4 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=95724 [article]

Satellites / Michel Capderou (2003)

Public Titre : Satellites : orbites et missions Type de document : Guide/Manuel Auteurs : Michel Capderou, Auteur Editeur : Berlin, Heidelberg, Vienne, New York, ... : Springer Année de publication : 2003 Importance : 486 p. Format : 15 x 23 cm + 1 cédérom ISBN/ISSN/EAN : 978-2-287-59772-5 Langues : Français (fre) Descripteur : [Vedettes matières IGN] Techniques orbitales [Termes IGN] altitude [Termes IGN] échantillonnage d'image [Termes IGN] fauchée [Termes IGN] Mars (planète) [Termes IGN] mécanique céleste [Termes IGN] mécanique orbitale [Termes IGN] mission spatiale [Termes IGN] mouvement Képlerien [Termes IGN] orbite [Termes IGN] orbite géostationnaire [Termes IGN] orbite héliosynchrone [Termes IGN] orbite képlerienne [Termes IGN] orbite réelle [Termes IGN] orbite terrestre [Termes IGN] orientation de la Terre [Termes IGN] perturbation orbitale [Termes IGN] phase [Termes IGN] potentiel de pesanteur terrestre [Termes IGN] poursuite de satellite [Termes IGN] satellite artificiel [Termes IGN] satellite naturel [Termes IGN] trace au sol Résumé : (Editeur) Ce livre traite des orbites des satellites et montre comment leur grande diversité permet de répondre aux besoins de domaines aussi différents que les communications, le positionnement, la télédétection, la météorologie ou l'astronomie. L'ouvrage débute par une étude du satellite dans le cadre des lois de la mécanique spatiale. Il présente ensuite les diverses catégories d'orbites (orbite circulaire, elliptique, haute, basse, géostationnaire, héliosynchrone) et le problème de l'échantillonnage (quand et comment le satellite voit sa cible). Il se termine sur des études de cas concrets, toutes les notions abordées par les satellites terrestres étant mises en oeuvre pour un satellite en orbite autour de Mars. L'exposé est étayé par de nombreuses applications, figures et illustrations. Le propos s'appuie sur deux logiciels, IXION (orbitographie et échantillonnage) et ATLAS (cartographie) développés par l'auteur. Le cédérom fourni comporte un logiciel interactif permettant de déterminer l'orbite et l'échantillonnage d'un satellite. Note de contenu : 1/ Mouvement Képlérien 2/ Satellite en orbite képlérienne 3/ Satellite en orbite réelle (pertubée) 4/ Mouvements orbite / Terre / Soleil 5/ Orbite et trace du satellite 6/ Orbite par rapport au soleil : passage, heure 7/ Orbite par rapport à la Terre : phasage, altitude 8/ Vue depuis le satellite 9/ Echantillonnage temporel et angulaire 10/ Satellite de Mars 11/ Satellite d'un autre corps céleste Numéro de notice : 13152 Affiliation des auteurs : non IGN Thématique : IMAGERIE/POSITIONNEMENT Nature : Manuel Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=54895

Astronomie / Françoise Duquenne (1997)

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