Centre de documentation
scientifique

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)  

Public [article]  inAdvances in space research > vol 64 n°7 (1 October 2019) . - pp 1445 - 1454 Titre : Real-time clock prediction of multi-GNSS satellites and its application in precise point positioning Type de document : Article/Communication Auteurs : Yaquan Peng, Auteur ; Yidong Lou, Auteur ; Xiaopeng Gong, Auteur ; YinTong Wang, Auteur ; Xiaolei Dai, Auteur Année de publication : 2019 Article en page(s) : pp 1445 - 1454 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie spatiale [Termes IGN] horloge atomique [Termes IGN] horloge du satellite [Termes IGN] positionnement par BeiDou [Termes IGN] positionnement par Galileo [Termes IGN] positionnement par GNSS [Termes IGN] positionnement ponctuel précis [Termes IGN] prédiction [Termes IGN] temps réel Résumé : (auteur) With the development of Global Navigation Satellite System (GNSS), multi-GNSS is expected to greatly benefit precise point positioning (PPP), especially during the outage of real time service (RTS). In this paper, we focus on the performance of multi-GNSS satellite clock prediction and its application in real-time PPP. Based on the statistical analysis of multi-system satellite clock products, a model consisting of polynomial and periodic terms is employed for multi-system satellite clock prediction. To evaluate the method proposed, both post-processed and real-time satellite clock products are employed in simulated real-time processing mode. The results show that the accuracy of satellite clock prediction is related to atomic clock type and satellite type. For GPS satellites, the average standard deviations (STDs) of Cs atomic clocks will reach as high as 0.65 ns while the STD of Rb atomic clocks is only about 0.15 ns. As for BDS and Galileo, the average STD of 2-hour satellite clock prediction are 0.30 ns and 0.06 ns, respectively. In addition, it is validated that real-time PPP can still achieve positioning accuracy of one to three decimeters by using products of 2-hour satellite clock prediction. Moreover, compared to the results of GPS-only PPP, multi-system can greatly enhance the accuracy of real-time PPP from 12.5% to 18.5% in different situations. Numéro de notice : A2019-410 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1016/j.asr.2019.06.040 Date de publication en ligne : 08/07/2019 En ligne : https://doi.org/10.1016/j.asr.2019.06.040 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=93525 [article]

Refining ionospheric delay modeling for undifferenced and uncombined GNSS data processing / Qile Zhao in Journal of geodesy, vol 93 n° 4 (April 2019)  

Public [article]  inJournal of geodesy > vol 93 n° 4 (April 2019) . - pp 545 - 560 Titre : Refining ionospheric delay modeling for undifferenced and uncombined GNSS data processing Type de document : Article/Communication Auteurs : Qile Zhao, Auteur ; YinTong Wang, Auteur ; Shengfeng Gu, Auteur ; Fu Zheng, Auteur ; et al., Auteur Année de publication : 2019 Article en page(s) : pp 545 - 560 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Termes IGN] modèle déterministe [Termes IGN] modèle ionosphérique [Termes IGN] modèle stochastique [Termes IGN] positionnement ponctuel précis [Termes IGN] retard ionosphèrique [Vedettes matières IGN] Traitement de données GNSS Résumé : (Auteur) To access the full capabilities of multi-frequency signals from the modernized GPS, GLONASS and newly deployed BDS, Galileo, the undifferenced and uncombined observable model in which the individual signal of each frequency is treated as independent observable has drawn increasing interest in GNSS community. The ionosphere delay is the major issue in the undifferenced and uncombined observable model. Though several ionosphere delay parameterization approaches have been promoted, we argue that the functional model with only deterministic characteristic may not follow the irregular spatial and temporal variations. On the contrary, when the ionosphere delay is estimated as random walk or even white noise with only stochastic characteristic, the ionosphere terms turn out to be non-estimable or not sensitive to their absolute value. In the authors’ previous study, we have developed the deterministic plus stochastic ionosphere model, denoted as DESIGN, in which the deterministic part expressed with second-order polynomial is estimated as piece-wise constant over 5 min and the stochastic part is estimated as random walk with constrains derived based on statistics of 4 weeks data in 2010. In this contribution, we further model the deterministic part with Fourier series and update the variogram of the stochastic part accordingly based on two-year data collected by about 150 stations. From the statistic studies, it is concluded that the main frequency components are identical for different coefficients, different stations, as well as different ionosphere activity status, but with varying amplitude. Thus, in the Fourier series expression of the deterministic part, we fix the frequency and estimate the amplitude as daily constant unknowns. Concerning the stochastic component, the variation of variogram is both, geomagnetic latitude and ionosphere activity status dependent. Thus, we use the Gaussian function and Epstein function to model the variation of geomagnetic latitude and ionosphere activity status, respectively. Based on the undifferenced and uncombined observable model with ionosphere constrained with DESIGN, both dual-frequency and single-frequency PPP are carried out to demonstrate its efficiency with three-month data collected in 2010, 2014, and 2017 with different ionosphere activity status. The experimental results suggest that compared with ionosphere-free model and our previous method, the averaged 3D improvement of our new method is 17.8 and 7.6% for dual-frequency PPP, respectively. While for single-frequency PPP, the averaged 3D improvement is 37.0 and 14%, respectively. Numéro de notice : A2019-157 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-018-1180-9 Date de publication en ligne : 31/07/2019 En ligne : https://doi.org/10.1007/s00190-018-1180-9 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=92496 [article]