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Improving the (re-)convergence of multi-GNSS real-time precise point positioning through regional between-satellite single-differenced ionospheric augmentation / Ahao Wang in GPS solutions, vol 26 n° 2 (April 2022)  

Public [article]  inGPS solutions > vol 26 n° 2 (April 2022) . - n° 39 Titre : Improving the (re-)convergence of multi-GNSS real-time precise point positioning through regional between-satellite single-differenced ionospheric augmentation Type de document : Article/Communication Auteurs : Ahao Wang, Auteur ; Yize Zhang, Auteur ; Junping Chen, Auteur ; et al., Auteur Année de publication : 2022 Article en page(s) : n° 39 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Applications de géodésie spatiale [Termes IGN] correction ionosphérique [Termes IGN] modèle ionosphérique [Termes IGN] positionnement cinématique en temps réel [Termes IGN] positionnement ponctuel précis [Termes IGN] temps de convergence [Termes IGN] temps réel [Termes IGN] teneur verticale totale en électrons [Termes IGN] transformation polynomiale Résumé : (auteur) The long (re-)convergence time seriously limits many applications of real-time precise point positioning (RTPPP) in challenging environments like urban vehicle navigation and hazards monitoring. Thus, we proposed a real-time fast-positioning model by introducing the regional between-satellite single-differenced (SD) ionospheric constraints into the undifferenced and uncombined PPP (UU-PPP). The line-of-sight ionospheric observables are extracted by the multi-GNSS (GPS + Galileo) UU-PPP method. The polynomial function with simple structure and high efficiency is applied to establish the real-time regional between-satellite SD ionospheric vertical total electron content (VTEC) model. The differential slant total electron content (dSTEC) variations retrieved from three VTEC models are validated with the between-satellite SD and epoch-differenced geometry-free combinations of dual-frequency phase observations. The average RMS values are 0.77, 0.78 and 0.47 TEC unit for the CLK93 real-time VTEC, CODE final GIM and regional between-satellite SD ionospheric VTEC model, respectively. In the positioning domain, the data of ten stations for 12 consecutive days in 2020 were used for implementing kinematic RTPPP with single-frequency (SF) and dual-frequency (DF) observations. Compared with the GPS + Galileo SF-RTPPP based on the GRoup And PHase Ionospheric Correction model, the initialization time of the SD ionospheric-constrained (SDIC) SF-RTPPP when converged to 0.2 m at the 68% confidence level can be improved from 58 to 32 min in horizontal and 72 to 49 min in vertical, and its positioning accuracy can be improved by 29.7 and 20.3% in the horizontal and vertical components, respectively. Meanwhile, the re-convergence errors of SDIC SF-RTPPP from the first epoch can be maintained at 0.15 m in three components. As to GPS + Galileo SDIC DF-RTPPP, the re-convergence time when converged to 0.1 m can be lower than 3 min in horizontal and 9 min in vertical, and the re-convergence errors at the first epoch could even be lower than 0.15 m in horizontal. Hence, the new positioning model can maintain high accuracy and improve the continuity of real-time kinematic positioning in a short time when the number of tracked satellites in the urban or canyon environment was greatly dropped due to signal blocking. Numéro de notice : A2022-107 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article DOI : 10.1007/s10291-022-01229-z Date de publication en ligne : 21/02/2022 En ligne : https://doi.org/10.1007/s10291-022-01229-z Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=99608 [article]

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]

Performance of real-time precise point positioning / Junping Chen in Marine geodesy, vol 36 n° 1 (January - March 2013)  

Public [article]  inMarine geodesy > vol 36 n° 1 (January - March 2013) . - pp 98 - 108 Titre : Performance of real-time precise point positioning Type de document : Article/Communication Auteurs : Junping Chen, Auteur ; Haojun Li, Auteur ; Bin Wu, Auteur ; et al., Auteur Année de publication : 2013 Article en page(s) : pp 98 - 108 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Navigation et positionnement [Termes IGN] horloge atomique [Termes IGN] orbite [Termes IGN] positionnement ponctuel précis [Termes IGN] récepteur monofréquence [Termes IGN] temps réel Résumé : (Auteur) The IGS Real-time Pilot Project (IGS-RTPP) provides real-time precise orbits and clocks, which support real-time positioning for single stations over large areas using the Precise Point Positioning (PPP) technique. This paper investigates the impact of real-time orbits, network configuration, and analysis strategies on real-time PPP implementation and demonstrates the real-time PPP performance. One month of data from the IGS network is analyzed in a real-time simulation mode. Results reveal the following: (1) In clock estimation, differential approaches are much more efficient than the zero-differenced approach. (2) The precision of IGS Ultra rapid (IGU) orbits could meet the IGS-RTPP requirement for precise clock estimation and PPP positioning. (3) Considering efficiency and precision, a network with 50 stations is recommended for the IGS-RTPP. It is demonstrated that the real-time satellite clock precision is 0.1 ns supporting hourly static PPP with a mean precision of 2–3 cm in the North component and 3–4 cm in the other components. Kinematic PPP assessed with onboard GPS data collected from a buoy provided mean coordinate precision of 2.2, 4.2, 6.1 cm in the North, East and Up directions, compared to the RTK solutions. Numéro de notice : A2013-248 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article DOI : 10.1080/01490419.2012.699503 Date de publication en ligne : 13/03/2013 En ligne : https://doi.org/10.1080/01490419.2012.699503 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=32386 [article]

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230-2013011	RAB	Revue	Centre de documentation	En réserve L003	Disponible