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Generating GPS decoupled clock products for precise point positioning with ambiguity resolution / Shuai Liu in Journal of geodesy, vol 96 n° 1 (January 2022)  

Public [article]  inJournal of geodesy > vol 96 n° 1 (January 2022) . - n° 6 Titre : Generating GPS decoupled clock products for precise point positioning with ambiguity resolution Type de document : Article/Communication Auteurs : Shuai Liu, Auteur ; Yunbin Yan, Auteur Année de publication : 2021 Article en page(s) : n° 6 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie spatiale [Termes IGN] erreur de phase [Termes IGN] horloge du récepteur [Termes IGN] modèle stochastique [Termes IGN] onde porteuse [Termes IGN] positionnement cinématique [Termes IGN] positionnement ponctuel précis [Termes IGN] résolution d'ambiguïté Résumé : (auteur) Carrier-phase integer ambiguity resolution (AR) is the key to improving the positioning accuracy of precise point positioning (PPP). However, in theory, the integer property of ambiguities in PPP are destroyed due to the absorption of phase biases. In this study, we analyzed a set of clock products consisting of a code clock, phase clock and wide-lane (WL) bias based on the decoupled clock (DCK) model, to facilitate PPP AR. The determination of the datum of the receiver clock as well as ambiguity were analyzed in detail to arrive at ways to eliminate rank deficiency. To fix ambiguity at the server end, we propose an approach by rounding directly with “fixing solution” (FS) and “partial ambiguity hold” (PAH) strategies, to increase the fixing rate and avoid the biased solution resulting from ambiguity datum loss. With respect to the International GNSS Service (IGS) legacy clocks, the mean standard deviations (STDs) of the phase clock and code clock were about 0.02 and 1.05 ns respectively, while the WL bias was about 0.12 cycles. Additionally, the convergence speed and stability of the decoupled phase clock are significantly improved compared with the conventional PPP model. Experiments on PPP positioning performance were conducted using 1 week of GPS data from more than 100 stations, considering the IGS weekly solutions as a benchmark. The ambiguity-fixed PPP with decoupled clocks had almost the same accuracy as the integer-recovered clock model, but the average accuracy improvements compared with the conventional PPP model in the east, north, and up components were 59.2, 32.4, and 20.3%, respectively, in the static mode, and approximately 38.0, 26.2, and 19.2% in the kinematic mode. These results demonstrate that users can achieve ambiguity-fixed solutions and obtain high-precision positioning coordinates with our decoupled clock products. Numéro de notice : A2022-093 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-021-01593-7 En ligne : https://doi.org/10.1007/s00190-021-01593-7 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=99517 [article]

Real-time GNSS precise point positioning using improved robust adaptive Kalman filter / Abdelsatar Elmezayen in Survey review, Vol 53 n° 381 (November 2021)  

Public [article]  inSurvey review > Vol 53 n° 381 (November 2021) . - pp 528 - 542 Titre : Real-time GNSS precise point positioning using improved robust adaptive Kalman filter Type de document : Article/Communication Auteurs : Abdelsatar Elmezayen, Auteur ; Ahmed El-Rabbany, Auteur Année de publication : 2021 Article en page(s) : pp 528 - 542 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie spatiale [Termes IGN] erreur de positionnement [Termes IGN] filtre adaptatif [Termes IGN] filtre de Kalman [Termes IGN] phase [Termes IGN] positionnement par Galileo [Termes IGN] positionnement par GNSS [Termes IGN] positionnement ponctuel précis [Termes IGN] temps réel [Termes IGN] valeur aberrante Résumé : (Auteur) Multi-constellation GNSS precise point positioning (PPP) typically uses the extended Kalman filter (EKF) for kinematic applications. Unfortunately, the obtained positioning accuracy in this approach is prone to errors caused by measurement outliers and the system’s dynamic model. An adaptive robust Kalman filter (RKF) was recently developed to mitigate these errors. However, RKF uses empirical values as detection thresholds for the outliers, which requires the measurements to be from the same constellation and of equal precision to obtain an optimal PPP solution. The classification robust adaptive Kalman filter (CAKF) has subsequently been developed to deal with measurements of different precisions, namely pseudorange and carrier-phase measurements. This paper proposes a real-time GPS/Galileo PPP system, which employs a modified version of CAKF called the Improved Robust adaptive Kalman Filter (IRKF). The positioning performance of GPS/Galileo PPP through the IRKF is initially verified in comparison with those obtained through the EKF, RKF, and CAKF using the Centre for Orbit Determination in Europe (CODE) final orbit and clock products in both of static and kinematic modes. The real-time GPS/Galileo PPP solution through the IRKF is then assessed in comparison with its near-real-time counterpart. The results indicate that when the IRKF approach is utilised, the positioning accuracy is significantly improved and the convergence behaviour is enhanced compared with results from EKF, conventional RKF, and CAKF. In the real-time mode, centimeter-level horizontal positioning accuracy is achieved under an open sky environment, while decimeter-level horizontal positioning accuracy is achieved under a challenging environment. On the other hand, decimeter-level accuracy is achieved for the vertical positioning component under all environmental scenarios. Moreover, the positioning accuracy of the real-time solution is comparable to the near-real-time counterpart. Numéro de notice : A2021-914 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1080/00396265.2020.1846361 Date de publication en ligne : 23/11/2020 En ligne : https://doi.org/10.1080/00396265.2020.1846361 Format de la ressource électronique : URL Article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=99317 [article]

Python software to transform GPS SNR wave phases to volumetric water content / Angel Martín in GPS solutions, vol 26 n° 1 (January 2022)  

Public [article]  inGPS solutions > vol 26 n° 1 (January 2022) . - n° 7 Titre : Python software to transform GPS SNR wave phases to volumetric water content Type de document : Article/Communication Auteurs : Angel Martín, Auteur ; Ana Belén Anquela, Auteur ; Sara Ibáñez, Auteur ; et al., Auteur Année de publication : 2021 Article en page(s) : n° 7 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie spatiale [Termes IGN] humidité du sol [Termes IGN] phase [Termes IGN] Python (langage de programmation) [Termes IGN] rapport signal sur bruit [Termes IGN] réflectométrie par GNSS [Termes IGN] signal GPS [Termes IGN] teneur en vapeur d'eau Résumé : (auteur) The global navigation satellite system interferometric reflectometry is often used to extract information about the environment surrounding the antenna. One of the most important applications is soil moisture monitoring. This manuscript presents the main ideas and implementation decisions needed to write the Python code to transform the derived phase of the interferometric GPS waves, obtained from signal-to-noise ratio data continuously observed during a period of several weeks (or months), to volumetric water content. The main goal of the manuscript is to share the software with the scientific community to help users in the GPS-IR computation. Numéro de notice : A2022-004 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s10291-021-01190-3 Date de publication en ligne : 27/10/2021 En ligne : https://doi.org/10.1007/s10291-021-01190-3 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=98919 [article]

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

Public [article]  inJournal of geodesy > vol 95 n° 11 (November 2021) . - n° 122 Titre : Ionospheric tomographic common clock model of undifferenced uncombined GNSS measurements Type de document : Article/Communication Auteurs : German Olivares-Pulido, Auteur ; Manuel Hernández-Pajares, Auteur ; Haixia Lyu, Auteur ; et al., Auteur Année de publication : 2021 Article en page(s) : n° 122 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Termes IGN] correction ionosphérique [Termes IGN] horloge du satellite [Termes IGN] mesurage par GNSS [Termes IGN] modèle ionosphérique [Termes IGN] phase [Termes IGN] positionnement ponctuel précis [Termes IGN] teneur totale en électrons [Termes IGN] tomographie par GPS [Termes IGN] voxel [Termes IGN] Wide Area Augmentation System [Vedettes matières IGN] Traitement de données GNSS Résumé : (auteur) In this manuscript, we introduce the Ionospheric Tomographic Common Clock (ITCC) model of undifferenced uncombined GNSS measurements. It is intended for improving the Wide Area precise positioning in a consistent and simple way in the multi-GNSS context, and without the need of external precise real-time products. This is the case, in particular, of the satellite clocks, which are estimated at the Wide Area GNSS network Central Processing Facility (CPF) referred to the reference receiver one; and the precise realtime ionospheric corrections, simultaneously computed under a voxel-based tomographic model with satellite clocks and other geodetic unknowns, from the uncombined and undifferenced pseudoranges and carrier phase measurements at the CPF from the Wide Area GNSS network area. The model, without fixing the carrier phase ambiguities for the time being (just constraining them by the simultaneous solution of both ionospheric and geometric components of the uncombined GNSS model), has been successfully applied and assessed against previous precise positioning techniques. This has been done by emulating real-time conditions for Wide Area GPS users during 2018 in Poland. Numéro de notice : A2021-776 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-021-01568-8 Date de publication en ligne : 13/10/2021 En ligne : https://doi.org/10.1007/s00190-021-01568-8 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=98839 [article]

Visualization of GNSS multipath effects and its potential application in IGS data processing / Weiming Tang in Journal of geodesy, vol 95 n° 9 (September 2021)  

Public [article]  inJournal of geodesy > vol 95 n° 9 (September 2021) . - n° 103 Titre : Visualization of GNSS multipath effects and its potential application in IGS data processing Type de document : Article/Communication Auteurs : Weiming Tang, Auteur ; Yawei Wang, Auteur ; Xuan Zou, Auteur ; et al., Auteur Année de publication : 2021 Article en page(s) : n° 103 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Termes IGN] grille [Termes IGN] interférence [Termes IGN] international GPS service for geodynamics [Termes IGN] modèle d'erreur [Termes IGN] phase [Termes IGN] positionnement cinématique [Termes IGN] qualité des données [Termes IGN] trajet multiple [Vedettes matières IGN] Traitement de données GNSS Résumé : (auteur) A modified multipath error mitigation method using the multi-point hemispherical grid model (MHGM) is proposed, and the influence of changes in the observation environments of IGS stations on their data quality is evaluated. The multipath error models of different satellite pairs for different observation periods can be established using the integrated multi-GNSS data in the proposed method. The test under deliberate high multipath environment reveals that this method can effectively estimate the GNSS multipath error, detect and present the orientation of the interference sources around the station. The RMS of residuals and the kinematic positioning accuracy on day 237 of 2018 are improved by 68% and 61%, respectively. Compared with the empirical site model (ESM), which can also visualize the effects of the multipath, the RMS of residuals when applying the MHGM is improved by 20%. The test with IGS historical observations shows that MHGM can effectively reflect the influence of changing multipath interference around stations on carrier phase observations, with an average improvement of 25% in the RMS of carrier phase residuals in the extrapolated 9-day validations over the past 18 years. The results of a kinematic positioning experiment in 2019 generally coincide with the RMS statistic results of carrier phase residuals as well. The MHGM demonstrates distinct potential in the influence evaluation of changes for the multipath interference around the stations on their observation quality. Numéro de notice : A2021-625 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-021-01559-9 Date de publication en ligne : 28/08/2021 En ligne : https://doi.org/10.1007/s00190-021-01559-9 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=98249 [article]

Comparison of polar ionospheric behavior at Arctic and Antarctic regions for improved satellite-based positioning / Arun Kumar Singh in Journal of applied geodesy, vol 15 n° 3 (July 2021)  

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GNSS-based statistical analysis of ionospheric anomalies during typhoon landings in Taiwan/Japan / Hai Peng in IEEE Transactions on geoscience and remote sensing, vol 59 n° 6 (June 2021)  

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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])  

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Impact of the third frequency GNSS pseudorange and carrier phase observations on rapid PPP convergences / Jiang Guo in GPS solutions, vol 25 n° 2 (April 2021)  

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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 highly adaptable method for GNSS cycle slip detection and repair based on Kalman filter / Xianwen Yu in Survey review, Vol 53 n° 377 (February 2021)  

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Integrated Kalman filter of accurate ranging and tracking with wideband radar / Shaopeng Wei in IEEE Transactions on geoscience and remote sensing, Vol 58 n° 12 (December 2020)  

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An assessment of wide-lane ambiguity resolution methods for multi-frequency multi-GNSS precise point positioning / Viet Duong in Survey review, vol 52 n° 374 (August 2020)  

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Precise point positioning with decimetre accuracy using wide-lane ambiguities and triple-frequency GNSS data / Manoj Deo in Journal of applied geodesy, vol 14 n° 3 (July 2020)  

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Improved kinematic precise point positioning performance with the use of map constraints / Emerson Pereira Cavalheri in Journal of applied geodesy, vol 14 n° 2 (April 2020)  

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