Centre dedocumentation
scientifique

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]

A new ambiguity resolution method for LEO precise orbit determination / Xingyu Zhou in Journal of geodesy, vol 96 n° 7 (July 2022)  

Public [article]  inJournal of geodesy > vol 96 n° 7 (July 2022) . - n° 49 Titre : A new ambiguity resolution method for LEO precise orbit determination Type de document : Article/Communication Auteurs : Xingyu Zhou, Auteur ; Hua Chen, Auteur ; Weiping Jiang, Auteur ; et al., Auteur Année de publication : 2022 Article en page(s) : n° 49 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Techniques orbitales [Termes IGN] orbite basse [Termes IGN] orbitographie [Termes IGN] récepteur GNSS [Termes IGN] résolution d'ambiguïté Résumé : (auteur) Ambiguity resolution (AR) is an effective approach to improve the orbit accuracy of the low Earth orbit satellites using the Global Navigation Satellite System (GNSS). The most commonly used single-difference (SD) AR requires prior knowledge of the GNSS hardware biases, while the potential unavailability of the bias products may hinder the AR process for users. The track-to-track (T2T) AR can work as an alternative without the GNSS bias products, but the performance may be degraded by the receiver hardware biases. To provide a better alternative in this condition, a new AR method called SD T2T (SDT2T) is proposed in this study, where the GNSS and receiver biases can be greatly eliminated without external knowledge. The performance of the SD AR, SDT2T AR, and T2T AR methods are assessed based on the gravity recovery and climate experiment follow on and SWARM data. The results show that the improvements contributed by the SDT2T AR are comparable to the SD AR. The multiple iterations required by the T2T AR can be avoided by the SDT2T AR, and the accuracy of the T2T AR can be further improved with the preprocessed ambiguities of the SDT2T AR. Considering the efficiency and stable performance, the SDT2T AR is recommended as the preferred alternative single-receiver AR method in the absence of the GNSS hardware bias products. Numéro de notice : A2022-590 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-022-01629-6 Date de publication en ligne : 15/07/2022 En ligne : https://doi.org/10.1007/s00190-022-01629-6 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=101272 [article]

Adaptive Kalman filter for real-time precise orbit determination of low earth orbit satellites based on pseudorange and epoch-differenced carrier-phase measurements / Min Li in Remote sensing, vol 14 n° 9 (May-1 2022)  

Public [article]  inRemote sensing > vol 14 n° 9 (May-1 2022) . - n° 2273 Titre : Adaptive Kalman filter for real-time precise orbit determination of low earth orbit satellites based on pseudorange and epoch-differenced carrier-phase measurements Type de document : Article/Communication Auteurs : Min Li, Auteur ; Tianhe Xu, Auteur ; Yali Shi, Auteur ; et al., Auteur Année de publication : 2022 Article en page(s) : n° 2273 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Techniques orbitales [Termes IGN] ambiguïté entière [Termes IGN] filtre adaptatif [Termes IGN] filtre de Kalman [Termes IGN] matrice de covariance [Termes IGN] mesurage de phase [Termes IGN] orbite basse [Termes IGN] orbitographie [Termes IGN] orbitographie par GNSS [Termes IGN] temps réel Résumé : (auteur) Real-time precise orbit determination (POD) of low earth orbiters (LEOs) is crucial for orbit maintenance as well as autonomous operation for space missions. The Global Positioning System (GPS) has become the dominant technique for real-time precise orbit determination (POD) of LEOs. However, the observation conditions of near-earth space are more critical than those on the ground. Real-time POD accuracy can be seriously affected when the observation environment suffers from strong space events, i.e., a heavy solar storm. In this study, we proposed a reliable adaptive Kalman filter based on pseudorange and epoch-differenced carrier-phase measurements. This approach uses the epoch-differenced carrier phase to eliminate the ambiguities and thus reduces the significant number of unknown parameters. Real calculations demonstrate that four to five observed GPS satellites is sufficient to solve reliable position parameters. Furthermore, with accurate pseudorange and epoch-differenced carrier-phase-based reference orbits, orbital dynamic disturbance can be detected precisely and reliably with an adaptive Kalman filter. Analyses of Swarm-A POD show that sub-meter level real-time orbit solutions can be obtained when the observation conditions are good. For poor observation conditions such as the GRACE-A satellite on 8 September 2017, when fewer than five GPS satellites were observed for 14% of the observation time, 1–2 m orbital accuracy can still be achieved with the proposed approach. Numéro de notice : A2022-386 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article DOI : 10.3390/rs14092273 Date de publication en ligne : 08/05/2022 En ligne : https://doi.org/10.3390/rs14092273 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=100665 [article]

Effect of PCV and attitude on the precise orbit determination of Jason-3 satellite / Kai Li in Journal of applied geodesy, vol 16 n° 2 (April 2022)  

Public [article]  inJournal of applied geodesy > vol 16 n° 2 (April 2022) . - pp 143 - 150 Titre : Effect of PCV and attitude on the precise orbit determination of Jason-3 satellite Type de document : Article/Communication Auteurs : Kai Li, Auteur ; Xuhua Zhou, Auteur ; Nannan Guo, Auteur ; et al., Auteur Année de publication : 2022 Article en page(s) : pp 143 - 150 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Techniques orbitales [Termes IGN] capteur d'orientation [Termes IGN] centre de phase [Termes IGN] données Jason [Termes IGN] orbite basse [Termes IGN] orbitographie [Termes IGN] perturbation orbitale Résumé : (auteur) Satellite attitude modes and antenna phase center variations have a great influence on the Precise Orbit Determination (POD) of Low Earth Orbit satellites (LEOs). Inaccurate information about spacecraft attitude, phase center offsets and variations in the POD leads to orbital error. The Jason-3 satellite experienced complex attitude modes which are fixed, sinusoidal, ramp-up/down and yaw-flip. Therefore, it is necessary to properly construct the attitude model in the process of POD especially when there is no external attitude data. For the antenna phase center correction, the PCO which is the deviation between Antenna Reference Point (ARP) and Mean Antenna Phase Center (MAPC) usually can be calibrated on the ground accurately, but the PCV which is the deviation between Instantaneous Antenna Phase Center (IAPC) and Mean Antenna Phase Center (MAPC) will change greatly with the change of space environment. Residual approach can be used to estimate the receiver PCV map. In this paper, we collected the on-board GPS data of Jason-3 satellite from January 2019 and analyzed the impacts of PCV and spacecraft attitude on the orbit accuracy by performing the reduced-dynamic POD. Compared with the reference orbit released by the Centre National d’Études Spatiales (CNES), using the PCV map can reduce the Root Mean Square (RMS) of orbit differences in the Radial (R), Along-track (T), Cross-track (N) and 3D direction about 0.3, 1.0, 0.9, and 1.4 mm. Based on the estimated PCV map, the orbit accuracy in R, T, N and 3D direction is 1.24, 2.81, 1.17, and 3.29 cm respectively by using the measured attitude data. When using the attitude model, the orbit accuracy in R, T, N and 3D directions is 1.60, 3.54, 1.33, and 4.13 cm, respectively. The results showed that the combination of measured attitude data and modeled PCV map can obtain the better orbit solution. It is essential to build a corresponding model in high-precision orbit determination, when there is no attitude data and PCV map. Numéro de notice : A2022-251 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article DOI : 10.1515/jag-2021-0052 Date de publication en ligne : 26/01/2022 En ligne : https://doi.org/10.1515/jag-2021-0052 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=100204 [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]

Calibrating GNSS phase biases with onboard observations of low earth orbit satellites / Xingxing Li in Journal of geodesy, vol 96 n° 2 (February 2022)  

Permalink

Comparison of atmospheric mass density models using a new data source: COSMIC satellite ephemerides / Yang Yang in IEEE Aerospace and Electronic Systems Magazine, vol 37 n° 2 (February 2022)  

Permalink

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

Permalink

GPS satellite differential code bias estimation with current eleven low earth orbit satellites / Xingxing Li in Journal of geodesy, vol 95 n° 7 (July 2021)  

Permalink

Integer phase clock method with single-satellite ambiguity fixing and its application in LEO satellite orbit determination / Kai Shao in Acta Geodaetica et Cartographica Sinica, vol 50 n° 4 ([20/04/2021])  

Permalink

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)  

Permalink

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

Permalink

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)  

Permalink

Comparison of atmospheric mass density models using a new data source: COSMIC satellite ephemerides / Yang Yang (2020)  

Permalink

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

Permalink