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BDS-3 precise orbit and clock solution at Wuhan University: status and improvement / Jing Guo in Journal of geodesy, vol 97 n° 2 (February 2023)  

Public [article]  inJournal of geodesy > vol 97 n° 2 (February 2023) . - n° 15 Titre : BDS-3 precise orbit and clock solution at Wuhan University: status and improvement Type de document : Article/Communication Auteurs : Jing Guo, Auteur ; Guo Chen, Auteur ; Xiaolong Xu, Auteur ; et al., Auteur Année de publication : 2023 Article en page(s) : n° 15 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Techniques orbitales [Termes IGN] horloge du satellite [Termes IGN] orbite précise [Termes IGN] orbitographie [Termes IGN] positionnement par BeiDou [Termes IGN] rayonnement solaire [Termes IGN] signal BeiDou Résumé : (auteur) With the rapid deployment of the third-generation satellites of the BeiDou Navigation Satellite System (BDS-3), Wuhan University (WHU) has incorporated BDS-3 satellites to its routine Multi-GNSS analysis since Day of Year 1, 2019. This article summarizes the processing strategy and presents the validation results of the WHU BDS-3 orbit and clock solutions submitted to the International GNSS Service Multi-GNSS Experiment in 2019. Although more than 200 stations with B1I and B3I signals tracking capability can be used for BDS-3 precise orbit determination, the number of tracking stations for different satellites diverges greatly; in general, more stations track those launched early and less those deployed late. The validations with orbit boundary misclosures, orbit differences with respect to BDS-3 products of GeoForschungsZentrum (GFZ) and Satellite Laser Ranging (SLR) residuals show that the orbits are affected by the number of tracking stations and the deficiency of dynamic models. To overcome the latter, an a priori solar radiation pressure (SRP) model has been proposed considering the Earth albedo and antenna thrust. The SLR validation shows that the new SRP model significantly improves the orbit from 5 to 7 cm to about 3 to 4 cm by reducing the Sun-elongation-angle-dependent errors of the BDS-3 orbits. Besides, the clock products have been compared with those of GFZ, and the root-mean-square (RMS) of clock linear fit is also analyzed. Noticeable different quality has been shown for Rubidium Atomic Frequency Standard and Passive Hydrogen Maser (PHM) clocks. The Sun-elevation-angle-dependent patterns are identified in PHM clocks, and the RMS of clock linear fit of PHM clocks can be reduced with improved dynamic modeling, particularly in eclipse seasons. Numéro de notice : A2023-131 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-023-01705-5 En ligne : https://doi.org/10.1007/s00190-023-01705-5 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=102674 [article]

Improving undifferenced precise satellite clock estimation with BDS-3 quad-frequency B1I/B3I/B1C/B2a observations for precise point positioning / Guoqiang Jiao in GPS solutions, vol 27 n° 1 (January 2023)  

Public [article]  inGPS solutions > vol 27 n° 1 (January 2023) . - n° 28 Titre : Improving undifferenced precise satellite clock estimation with BDS-3 quad-frequency B1I/B3I/B1C/B2a observations for precise point positioning Type de document : Article/Communication Auteurs : Guoqiang Jiao, Auteur ; Shuli Song, Auteur ; Ke Su, Auteur Année de publication : 2023 Article en page(s) : n° 28 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie spatiale [Termes IGN] décalage d'horloge [Termes IGN] données BeiDou [Termes IGN] erreur systématique interfréquence d'horloge [Termes IGN] fréquence multiple [Termes IGN] horloge du satellite [Termes IGN] positionnement ponctuel précis Résumé : (auteur) Estimates of satellite clock offsets typically employ dual-frequency undifferenced (UD) ionospheric-free (IF) observations from global network. The third-generation BeiDou Navigation Satellite System (BDS-3) can transmit B1I (1561.098 MHz), B3I (1268.52 MHz), B1C (1575.42 MHz), B2a (1176.45 MHz), B2b (1207.14 MHz) and B2ab (1191.795 MHz) signals. To make full use of the advantage of BDS-3 multi-frequency signals and improve BDS-3 service performance, we present some new quad-frequency satellite clock estimation techniques using B1I/B3I/B1C/B2a signals, which are QFIF0 model combining B1I/B3I and B1C/B2a IF observables, QFIF1 model combining the B1I/B3I, B3I/B1C and B1I/B2a IF observables, QFIF2 model combining B1I/B3I and B1I/B3I/B1C/B2a IF observables, and quad-frequency uncombined QFUC model, respectively. These new techniques only improve the performance of satellite clock estimation by fully utilizing the BDS-3 multi-frequency observations on the premise of ensuring the dual-frequency IF datum but also obtain the corresponding inter-frequency clock bias (IFCB) simultaneously. The quad-frequency satellite clock offsets are evaluated in terms of the clock offset precision, the modified Allan deviation (MDEV) and precise point positioning (PPP) performances. The new methods can improve the performances of the estimated clock offsets compared with the traditional dual-frequency IF model. The precision for the estimated clock offsets using quad-frequency satellite clock estimation models can be improved by 13–26% in terms of standard deviation (STD). The improvement of frequency stability ranges from 0 to 24%, especially for the short-term stability, which can reach 12% and 24% for B1I/B3I and B1C/B2a clock offsets, respectively. Similarly, the corresponding PPP performance has also been better improved with respect to those of using traditional dual-frequency IF clock offsets. Thus, the proposed quad-frequency satellite clock estimation techniques can be well applied into precise satellite clock estimation. Numéro de notice : A2023-025 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s10291-022-01364-7 Date de publication en ligne : 29/11/2022 En ligne : https://doi.org/10.1007/s10291-022-01364-7 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=102260 [article]

Orbit determination, clock estimation and performance evaluation of BDS-3 PPP-B2b service / Chengpan Tang in Journal of geodesy, vol 96 n° 9 (September 2022)  

Public [article]  inJournal of geodesy > vol 96 n° 9 (September 2022) . - n° 60 Titre : Orbit determination, clock estimation and performance evaluation of BDS-3 PPP-B2b service Type de document : Article/Communication Auteurs : Chengpan Tang, Auteur ; Xiaogong Hu, Auteur ; Jinping Chen, Auteur ; et al., Auteur Année de publication : 2022 Article en page(s) : n° 60 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie spatiale [Termes IGN] filtre de Kalman [Termes IGN] horloge du satellite [Termes IGN] orbitographie [Termes IGN] positionnement par BeiDou [Termes IGN] positionnement ponctuel précis [Termes IGN] temps réel Résumé : (auteur) This paper focuses on PPP-B2b, one of the featured services for BDS-3, which provides users around China with centimetre-level static positioning accuracy and decimetre-level kinematic positioning accuracy by broadcasting precise corrections for GPS/BDS-3 satellites. The GEO PPP-B2b signal broadcasted information types, including the PRN mask, orbit corrections, differential code bias corrections and clock corrections, are introduced, as well as a brief description of their usage. A new orbit determination strategy using regional L-band code/phase measurements and inter-satellite link measurements in combination and a real-time clock estimation strategy based on the Kalman filter for PPP-B2b precise correction generation are introduced in this contribution. Then, the accuracy of the orbit and clock corrections is assessed. The orbit user ranging error (URE) is 0.05 m for the BDS-3 MEO and GPS satellites. The orbit URE for BDS-3 IGSO satellites is worse, i.e., 0.15 m. The clock correction accuracy is 0.2 ns for BDS-3 and GPS satellites. Finally, the PPP-B2b performance is validated by both the static PPP process and simulated kinematic PPP process. BDS-3/GPS dual-system PPP offers faster convergence and better accuracy. The positioning accuracy achievable using PPP-B2b real-time products is at the same level as that using post-processed products. The RMS for BDS-3/GPS dual-system static positioning errors is less than 1.0 cm in east and north and about 3.0 cm in the up. The simulated kinematic positioning accuracy is better than 2.5 cm in the north, 3.5 cm in the east and 8.5 cm in the up directions after convergence. Numéro de notice : A2022-669 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-022-01642-9 Date de publication en ligne : 29/08/2022 En ligne : https://doi.org/10.1007/s00190-022-01642-9 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=101553 [article]

On the satellite clock datum stability of RT-PPP product and its application in one-way timing and time synchronization / Wenfei Guo in Journal of geodesy, vol 96 n° 8 (August 2022)  

Public [article]  inJournal of geodesy > vol 96 n° 8 (August 2022) . - n° 52 Titre : On the satellite clock datum stability of RT-PPP product and its application in one-way timing and time synchronization Type de document : Article/Communication Auteurs : Wenfei Guo, Auteur ; Hongming Zuo, Auteur ; Feiyu Mao, Auteur ; et al., Auteur Année de publication : 2022 Article en page(s) : n° 52 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie spatiale [Termes IGN] horloge du satellite [Termes IGN] positionnement ponctuel précis [Termes IGN] stabilité dans le temps [Termes IGN] station GNSS [Termes IGN] synchronisation [Termes IGN] temps réel [Termes IGN] variance d'Allan Résumé : (auteur) In real-time precise point positioning (RT-PPP), PPP one-way timing is used to steer local oscillators, but the timing performance could be significantly affected by the datum stability of the satellite clock product. To measure the stability of a satellite clock datum relative to the hydrogen maser (H-MASER) clock, a new GNSS satellite clock datum stability assessing model based on the overlapping Allan variance (AVAR) is proposed for both PPP one-way timing and time synchronization. Experiments were carried out with nine Global Navigation Satellite System (GNSS) stations at time laboratories with an external H-MASER clock to analyze the datum stability performance. In the experiments, RT satellite products from five RT Analysis Centers (ACs): CNES, ESA, GFZ, GMV, WHU, and the final satellite product from IGS were used in the comparison. Results show that the datum stability of all RT products tended to be similar, i.e., 6 to 8E−15/day, where WHU and GMV outperformed other RT ACs. Moreover, these datum stability results indicate that RT-PPP for steering local oscillators improves stability to 6 to 8E−15/day when selected with an appropriate RT product. The estimation noise in all RT ACs was at about the same level, i.e., 1 to 2E−15/day, but WHU delivered the most stable performance. Thus, datum stability is an effective guide for setting parameters and making long-term stability predictions when steering local oscillators, and satellite clock datum stability can be measured conveniently and quickly using the GNSS satellite clock datum stability assessing model proposed in this paper. Numéro de notice : A2022-608 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-022-01638-5 Date de publication en ligne : 08/08/2022 En ligne : https://doi.org/10.1007/s00190-022-01638-5 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=101388 [article]

LEO satellite clock analysis and prediction for positioning applications / Kan Wang in Geo-spatial Information Science, vol 25 n° 1 (March 2022)  

Public [article]  inGeo-spatial Information Science > vol 25 n° 1 (March 2022) . - pp 14 - 33 Titre : LEO satellite clock analysis and prediction for positioning applications Type de document : Article/Communication Auteurs : Kan Wang, Auteur ; Ahmed El-Mowafy, Auteur Année de publication : 2022 Article en page(s) : pp 14 - 33 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie spatiale [Termes IGN] chronométrie [Termes IGN] horloge du satellite [Termes IGN] orbite basse [Termes IGN] oscillateur [Termes IGN] relativité générale Résumé : (auteur) The positioning service aided by low Earth orbit (LEO) mega-constellations has become a hot topic in recent years. To achieve precise positioning, accuracy of the LEO clocks is important for single-receiver users. To bridge the gap between the applicable time of the clock products and the time of positioning, the precise LEO clocks need to be predicted over a certain period depending on the sampling interval of the clock products. This study discusses the prediction errors for periods from 10 s to 1 h for two typical LEO clock types, i.e. the ultra-stable oscillator (USO) and the oven-controlled crystal oscillator (OCXO). The prediction is based on GNSS-determined precise clock estimates, where the clock stability is related to the GNSS estimation errors, the behaviors of the oscillators themselves, the systematic effects related to the environment and the relativistic effects, and the stability of the time reference. Based on real data analysis, LEO clocks of the two different types are simulated under different conditions, and a prediction model considering the systematic effects is proposed. Compared to a simple polynomial fitting model usually applied, the proposed model can significantly reduce the prediction errors, i.e. by about 40%-70% in simulations and about 5%-30% for real data containing different miss-modeled effects. For both clock types, short-term prediction of 1 min would result in a root mean square error (RMSE) of a few centimeters when using a very stable time reference. The RMSE amounts to about 0.1 m, when a typical real-time time reference of the national center for space studies (CNES) real-time clocks was used. For long-term prediction of 1 h, the RMSE could range from below 1 m to a few meters for the USOs, depending on the complexity of the miss-modeled effects. For OCXOs, the 1 h prediction could lead to larger errors with an RMSE of about 10 m. Numéro de notice : A2022-303 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article DOI : 10.1080/10095020.2021.1917310 Date de publication en ligne : 08/06/2021 En ligne : https://doi.org/10.1080/10095020.2021.1917310 Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=100377 [article]

GNSS observable-specific phase biases for all-frequency PPP ambiguity resolution / Jianghui Geng in Journal of geodesy, vol 96 n° 2 (February 2022)  

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Ionospheric tomographic common clock model of undifferenced uncombined GNSS measurements / German Olivares-Pulido in Journal of geodesy, vol 95 n° 11 (November 2021)  

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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)  

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An offshore real-time precise point positioning technique based on a single set of BeiDou short-message communication devices / Zhixi Nie in Journal of geodesy, vol 94 n° 9 (September 2020)  

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GipsyX/RTGx, a new tool set for space geodetic operations and research / Willy I. Bertiger in Advances in space research, vol 66 n° 3 (1 August 2020)  

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Using quantum optical sensors for determining the Earth’s gravity field from space / Jurgen Müller in Journal of geodesy, vol 94 n° 8 (August 2020)  

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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)  

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Performance of real-time undifferenced precise positioning assisted by remote IGS multi-GNSS stations / Zhiqiang Liu in GPS solutions, vol 24 n° 2 (April 2020)  

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On the interoperability of IGS products for precise point positioning with ambiguity resolution / Simon Banville in Journal of geodesy, vol 94 n°1 (January 2020)  

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Real-time clock prediction of multi-GNSS satellites and its application in precise point positioning / Yaquan Peng in Advances in space research, vol 64 n°7 (1 October 2019)  

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