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Temporal spectrum of spatial correlations between GNSS station position time series / Yujiao Niu in Journal of geodesy, vol 97 n° 2 (February 2023)  

Public [article]  inJournal of geodesy > vol 97 n° 2 (February 2023) . - n° 12 Titre : Temporal spectrum of spatial correlations between GNSS station position time series Type de document : Article/Communication Auteurs : Yujiao Niu, Auteur ; Paul Rebischung , Auteur ; Min Li, Auteur ; Na Wei, Auteur ; Chuang Shi, Auteur ; Zuheir Altamimi , Auteur Année de publication : 2023 Article en page(s) : n° 12 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Termes IGN] analyse spatio-temporelle [Termes IGN] bruit blanc [Termes IGN] corrélation automatique de points homologues [Termes IGN] filtrage du bruit [Termes IGN] série temporelle [Termes IGN] station GNSS [Termes IGN] transformation de Fourier [Vedettes matières IGN] Traitement de données GNSS Résumé : (auteur) The background noise in Global Navigation Satellite Systems (GNSS) station position time series is known to be both temporally and spatially correlated. Its temporal correlations are well modeled and routinely taken into account when deriving parameters of interest like station velocities. On the other hand, a general model of the spatial correlations in GNSS time series is lacking, and they are usually ignored, although their consideration could benefit several purposes such as offset detection, velocity estimation or spatial filtering. In order to improve the realism of current spatio-temporal correlation models, we investigate in this study how the spatial correlations of GNSS time series vary with the temporal frequency. A frequency-dependent measure of the spatial correlations is therefore introduced and applied to station position time series from the latest reprocessing campaign of the International GNSS Service (IGS), as well as to Precise Point Positioning time series provided by the Nevada Geodetic Laboratory (NGL). Different spatial correlation regimes are thus evidenced at different temporal frequencies. The different levels of spatial correlations between IGS and NGL datasets furthermore suggest that some part of the spatially correlated background noise in GNSS time series consists of GNSS errors rather than aperiodic Earth surface deformation signal. Numéro de notice : A2023-226 Affiliation des auteurs : UMR IPGP-Géod+Ext (2020- ) Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-023-01703-7 Date de publication en ligne : 06/02/2023 En ligne : https://doi.org/10.1007/s00190-023-01703-7 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=102746 [article]

BDS and GPS side-lobe observation quality analysis and orbit determination with a GEO satellite onboard receiver / Wenwen Li in GPS solutions, vol 27 n° 1 (January 2023)  

Public [article]  inGPS solutions > vol 27 n° 1 (January 2023) . - n° 18 Titre : BDS and GPS side-lobe observation quality analysis and orbit determination with a GEO satellite onboard receiver Type de document : Article/Communication Auteurs : Wenwen Li, Auteur ; Kecai Jiang, Auteur ; Min Li, Auteur ; et al., Auteur Année de publication : 2023 Article en page(s) : n° 18 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Techniques orbitales [Termes IGN] code GNSS [Termes IGN] orbite géostationnaire [Termes IGN] orbite précise [Termes IGN] orbitographie [Termes IGN] orbitographie par GNSS [Termes IGN] phase [Termes IGN] positionnement par BeiDou [Termes IGN] positionnement par GPS Résumé : (auteur) Multi-GNSS combination can alleviate problems associated with GNSS-based geostationary earth orbit (GEO) satellite navigation and orbit determination (OD), such as GNSS availability and observation geometry deterioration. However, only GPS has been widely applied and investigated in GEO missions, whereas GEO OD with BDS requires further exploration. The Chinese GEO satellite TJS-5, equipped with a GPS and BDS-compatible receiver, is the first GEO mission that tracks both BDS 2nd and 3rd generation satellites since BDS global deployment. With the TJS-5 real onboard data, we evaluate BDS side-lobe signal performance and the BDS contribution to GEO OD. Due to transmit antenna gain deficiencies in the side lobes, BDS shows a worse tracking performance than GPS with an average satellite number of 4.3 versus 7.8. Both GPS and BDS reveal inconsistency between carrier-phase and code observations, which reaches several meters and significantly degrades post-dynamic OD calculation. We estimate the consistency as a random walk process in the carrier-phase observation model to reduce its impact. With inconsistency estimated, the post-fit carrier-phase residuals decrease from 0.21 to 0.09 m for both GPS and BDS. The OD precision is significantly improved, from 1.95 to 1.42 m with only GPS and from 3.14 to 2.71 m with only BDS; the GPS and BDS combined OD exhibits the largest improvement from 1.74 to 0.82 m, demonstrating that adding BDS improves the OD precision by 43.3%. The above results indicate that the proposed carrier-phase inconsistency estimation approach is effective for both GPS and BDS and can achieve an orbit precision within 1.0 m using multi-GNSS measurements. Numéro de notice : A2023-026 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s10291-022-01358-5 Date de publication en ligne : 06/11/2022 En ligne : https://doi.org/10.1007/s10291-022-01358-5 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=102261 [article]

Estimation of ionospheric total electron content using GNSS observations derived from a smartphone / Li Xu in GPS solutions, vol 26 n° 4 (October 2022)  

Public [article]  inGPS solutions > vol 26 n° 4 (October 2022) . - n° 138 Titre : Estimation of ionospheric total electron content using GNSS observations derived from a smartphone Type de document : Article/Communication Auteurs : Li Xu, Auteur ; Jiuping Zha, Auteur ; Min Li, Auteur ; et al., Auteur Année de publication : 2022 Article en page(s) : n° 138 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Applications de géodésie spatiale [Termes IGN] modèle ionosphérique [Termes IGN] phase [Termes IGN] pondération [Termes IGN] série de Fourier [Termes IGN] téléphone intelligent [Termes IGN] teneur totale en électrons [Termes IGN] teneur verticale totale en électrons Résumé : (auteur) The global navigation satellite system (GNSS) measurements to determine ionospheric total electron content (TEC) are mainly derived from expensive geodetic-grade receivers, which are not conducive to high-density placement. In this work, we present an analysis of the performance of ionospheric TEC determined by GNSS dual-frequency measurements derived from the smartphone, taking the Xiaomi 8 (XMI8) as an example. First, the ionospheric observable is retrieved from the code and carrier phase data using the carrier-to-code leveling technique and a new carrier-to-noise weighting strategy instead of an elevation weighting strategy, considering the characteristic of the GNSS measurements from smartphones. Then, the absolute ionospheric slant TEC (STEC) values are isolated from the ionospheric observables by modeling with the generalized trigonometric series function. The experimental data, covering over 120 h, were taken from two situations: one is the data collected by the original smartphone antenna; the other is the external geodetic-grade antenna. The TEC data obtained from the collocated geodetic-grade receiver are used as reference data to evaluate the performance of the TEC values from XMI8. Compared to the reference data, the evaluation results show that the ionospheric STEC extraction accuracy can reach total electron content unit (TECU) values of 0.17 and 0.11 under the two different situations in the continuous carrier phase satellite arc without cycle slips. In addition, the VTEC modeling accuracy is above 5 and 2 TECU in the two different situations, respectively. Thus, we concluded that consumer-level GNSS chipsets are highly potential in the future to increase the ionospheric monitoring station density due to their low costs and good data quality. Numéro de notice : A2022-713 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article DOI : 10.1007/s10291-022-01329-w Date de publication en ligne : 04/09/2022 En ligne : https://doi.org/10.1007/s10291-022-01329-w Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=101591 [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]

Quantifying discrepancies in the three-dimensional seasonal variations between IGS station positions and load models / Yujiao Niu in Journal of geodesy, vol 96 n° 4 (April 2022)  

Public [article]  inJournal of geodesy > vol 96 n° 4 (April 2022) . - n° 31 Titre : Quantifying discrepancies in the three-dimensional seasonal variations between IGS station positions and load models Type de document : Article/Communication Auteurs : Yujiao Niu, Auteur ; Na Wei, Auteur ; Min Li, Auteur ; Paul Rebischung , Auteur ; Chuang Shi, Auteur ; Guo Chen, Auteur Année de publication : 2022 Projets : 1-Pas de projet / Article en page(s) : n° 31 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie spatiale [Termes IGN] déformation de la croute terrestre [Termes IGN] déformation de surface [Termes IGN] effet de charge [Termes IGN] Europe (géographie politique) [Termes IGN] signal GNSS [Termes IGN] station GNSS [Termes IGN] surcharge atmosphérique [Termes IGN] surcharge hydrologique [Termes IGN] surcharge océanique [Termes IGN] variation saisonnière Résumé : (auteur) Seasonal deformation related to mass redistribution on the Earth’s surface can be recorded by continuous global navigation satellite system (GNSS) and simulated by surface loading models. It has been reported that obvious discrepancies exist in the seasonal deformation between GNSS estimates and modeled loading displacements, especially in the horizontal components. The three-dimensional seasonal deformation of 900 GNSS stations derived from the International GNSS Service (IGS) second reprocessing are compared with those obtained from geophysical loading models. The reduction ratio of the weighted mean amplitude of GNSS seasonal signals induced by loading deformation correction is adopted to evaluate the consistency of seasonal deformation between them. Results demonstrate that about 43% of GNSS-derived vertical annual deformation can be explained by the loading models, while in the horizontal components, it is less than 20%. To explore the remaining GNSS seasonal variations unexplained by loading models, the potential contributions from Inter-AC disagreement, GNSS draconitic errors, regional/local-scale loading and loading model errors are investigated also using the reduction ratio metric. Comparison of GNSS annual signals between each IGS analysis center (AC) and the IGS combined solutions indicate that more than 25% (horizontal) and 10% (vertical) of the annual discrepancies between GNSS and loading models can be attributed to Inter-AC disagreement caused by different data processing software implementations and/or choices of the analysis strategies. Removing the draconitic errors shows an improvement of about ~ 3% in the annual vertical reduction ratio for the stations with more than fifteen years observations. Moreover, significant horizontal discrepancies between GNSS and loading models are found for the stations located in Continental Europe, which may be dominated by the regional/local-scale loading. The loading model errors can explain at least 6% of the remaining GNSS annual variations in the East and Up components. It has been verified that the contribution of thermoelastic deformation to the GNSS seasonal variations is about 9% and 7% for the horizontal and vertical directions, respectively. Apart from these contributors, there are still ~ 50% (horizontal) and ~ 30% (vertical) of the GNSS annual variations that need to be explained. Numéro de notice : A2022-940 Affiliation des auteurs : UMR IPGP-Géod+Ext (2020- ) Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-022-01618-9 Date de publication en ligne : 25/04/2022 En ligne : https://doi.org/10.1007/s00190-022-01618-9 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=102745 [article]

Multi-GNSS real-time precise clock estimation considering the correction of inter-satellite code biases / Liang Chen in GPS solutions, vol 25 n° 2 (April 2021)  

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A multi-frequency and multi-GNSS method for the retrieval of the ionospheric TEC and intraday variability of receiver DCBs / Min Li in Journal of geodesy, vol 94 n° 10 (October 2020)  

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Real-Time Precise Point Positioning (RTPPP) with raw observations and its application in real-time regional ionospheric VTEC modeling / Teng Liu in Journal of geodesy, vol 92 n° 11 (November 2018)  

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Method for real-time self-calibrating GLONASS code inter-frequency bias and improvements on single point positioning / Liang Chen in GPS solutions, vol 22 n° 4 (October 2018)  

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Joint estimation of vertical total electron content (VTEC) and satellite differential code biases (SDCBs) using low-cost receivers / Baocheng Zhang in Journal of geodesy, vol 92 n° 4 (April 2018)  

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Precise orbit determination of the Fengyun-3C satellite using onboard GPS and BDS observations / Min Li in Journal of geodesy, vol 91 n° 11 (November 2017)  

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Estimation and analysis of Galileo differential code biases / Min Li in Journal of geodesy, vol 91 n° 3 (March 2017)  

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Real-time high-precision earthquake monitoring using single-frequency GPS receivers / Min Li in GPS solutions, vol 19 n° 1 (January 2015)  

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Initial results of precise orbit and clock determination for COMPASS navigation satellite system / Qile Zhao in Journal of geodesy, vol 87 n° 5 (May 2013)  

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