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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]

An accurate Kriging-based regional ionospheric model using combined GPS/BeiDou observations / Mohamed Abdelazeem in Journal of applied geodesy, vol 12 n° 1 (January 2018)  

Public [article]  inJournal of applied geodesy > vol 12 n° 1 (January 2018) . - pp 65 - 76 Titre : An accurate Kriging-based regional ionospheric model using combined GPS/BeiDou observations Type de document : Article/Communication Auteurs : Mohamed Abdelazeem, Auteur ; Rahmi N. Çelik, Auteur ; Ahmed El-Rabbany, Auteur Année de publication : 2018 Article en page(s) : pp 65 - 76 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie spatiale [Termes IGN] coordonnées GPS [Termes IGN] données BeiDou [Termes IGN] krigeage [Termes IGN] méthode des moindres carrés [Termes IGN] modèle ionosphérique [Termes IGN] positionnement ponctuel précis [Termes IGN] simple différence [Termes IGN] station de référence [Termes IGN] teneur verticale totale en électrons Résumé : (auteur) In this study, we propose a regional ionospheric model (RIM) based on both of the GPS-only and the combined GPS/BeiDou observations for single-frequency precise point positioning (SF-PPP) users in Europe. GPS/BeiDou observations from 16 reference stations are processed in the zero-difference mode. A least-squares algorithm is developed to determine the vertical total electron content (VTEC) bi-linear function parameters for a 15-minute time interval. The Kriging interpolation method is used to estimate the VTEC values at a 1 °×1 ° grid. The resulting RIMs are validated for PPP applications using GNSS observations from another set of stations. The SF-PPP accuracy and convergence time obtained through the proposed RIMs are computed and compared with those obtained through the international GNSS service global ionospheric maps (IGS-GIM). The results show that the RIMs speed up the convergence time and enhance the overall positioning accuracy in comparison with the IGS-GIM model, particularly the combined GPS/BeiDou-based model. Numéro de notice : A2018-015 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article DOI : 10.1515/jag-2017-0023 En ligne : https://doi.org/10.1515/jag-2017-0023 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=89094 [article]

Performance analysis of precise point positioning using multi-constellation GNSS : GPS, GLONASS, Galileo and BeiDou / Mahmoud Abd Rabbou in Survey review, vol 49 n° 352 (March 2017)  

Public [article]  inSurvey review > vol 49 n° 352 (March 2017) . - pp 39 - 50 Titre : Performance analysis of precise point positioning using multi-constellation GNSS : GPS, GLONASS, Galileo and BeiDou Type de document : Article/Communication Auteurs : Mahmoud Abd Rabbou, Auteur ; Ahmed El-Rabbany, Auteur Année de publication : 2017 Article en page(s) : pp 39 - 50 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie spatiale [Termes IGN] combinaison au niveau des observations [Termes IGN] performance [Termes IGN] positionnement par BeiDou [Termes IGN] positionnement par Galileo [Termes IGN] positionnement par GLONASS [Termes IGN] positionnement par GNSS [Termes IGN] positionnement par GPS [Termes IGN] positionnement ponctuel précis [Termes IGN] positionnement statique [Termes IGN] précision du positionnement [Termes IGN] simple différence Résumé : (Auteur) We developed a new GNSS PPP model, which combines the observations of GPS, GLONASS, Galileo and BeiDou satellite navigation systems for precise applications. Both undifferenced and between-satellite single-difference (BSSD) ionosphere-free GNSS PPP models are developed. The contribution of the new GNSS observations is assessed compared with the existing GPS and GPS/GLONASS PPP using three-hours GNSS static data positioning results for several GNSS stations and four consecutive days. Inter-system biases between GPS and other GNSS systems are obtained as additional unknowns in the developed PPP filter. The results indicate that both GPS and GPS/Galileo PPP present comparable positioning accuracy level, which is attributed to the limited number of Galileo satellites. The additional BeiDou observations enhances the positioning accuracy after 15 minutes by 5 cm, 4 cm and 9 cm in latitude, longitude and altitude, respectively compared with GPS only positioning accuracy. However, the BeiDou only PPP results present less accurate positioning accuracy compared with the GPS only PPP. The multi-constellation GNSS PPP enhances the positioning accuracy by 8 cm, 6 cm and 11 cm in latitude, longitude and altitude, respectively compared with the GPS PPP results. Compared with the undifferenced PPP results, the BSSD model enhances the positioning accuracy after 15 minutes for the different GNSS constellations based PPP. The GPS/Galileo PPP positioning accuracy improves by 30%, 27% and 10% in latitude, longitude and altitude, respectively and the GPS/BeiDou PPP positioning accuracy, enhances by 17%, 22% and 15% in latitude, longitude and altitude, respectively while the multi-constellation GNSS PPP positioning accuracy improves by 22% and 15% in latitude and altitude, respectively over the undifferenced PPP technique. Additionally, the BSSD model is found to be superior with respect to the convergence times for the different GNSS combinations based PPP over the traditional undifferenced PPP model. Numéro de notice : A2017-058 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article DOI : 10.1080/00396265.2015.1108068 En ligne : https://doi.org/10.1080/00396265.2015.1108068 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=84266 [article]

Precise point positioning model using triple GNSS constellations: GPS, Galileo and BeiDou / Akram Afifi in Journal of applied geodesy, vol 10 n° 4 (December 2016)  

Public [article]  inJournal of applied geodesy > vol 10 n° 4 (December 2016) . - pp 223 – 232 Titre : Precise point positioning model using triple GNSS constellations: GPS, Galileo and BeiDou Type de document : Article/Communication Auteurs : Akram Afifi, Auteur ; Ahmed El-Rabbany, Auteur Année de publication : 2016 Article en page(s) : pp 223 – 232 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie spatiale [Termes IGN] erreur de positionnement [Termes IGN] erreur systématique [Termes IGN] milieu urbain [Termes IGN] modèle mathématique [Termes IGN] positionnement par BeiDou [Termes IGN] positionnement par Galileo [Termes IGN] positionnement par GNSS [Termes IGN] positionnement par GPS [Termes IGN] positionnement ponctuel précis [Termes IGN] récepteur bifréquence [Termes IGN] temps réel Résumé : (auteur) This paper introduces a comparison between dual-frequency precise point positioning (PPP) post-processing model, which combines the observations of three different GNSS constellations, namely GPS, Galileo, and BeiDou and real-time PPP model. A drawback of a single GNSS system such as GPS, however, is the availability of sufficient number of visible satellites in urban areas. Combining GNSS observations offers more visible satellites to users, which in turn is expected to enhance the satellite geometry and the overall positioning solution. However, combining several GNSS observables introduces additional biases, which require rigorous modelling, including the GNSS time offsets and hardware delays. In this paper, a GNSS post-processing PPPP model is developed using ionosphere-free linear combination. The additional biases of the GPS, Galileo, and BeiDou combination are accounted for through the introduction of a new unknown parameter, which is identified as the inter-system bias, in the PPP mathematical model. Natural Resources Canada’s GPSPace PPP software is modified to enable a combined GPS / Galileo / BeiDou PPP solution and to handle the newly inter-system bias. A total of four data sets at four IGS stations are processed to verify the developed PPP model. Precise satellite orbit and clock products from the IGS-MGEX network are used to correct of the GPS, Galileo and BeiDou measurements. For the real-time PPP model the corrections of the satellites orbit and clock are obtained through the international GNSS service (IGS) real-time service (RTS). GPS and Galileo Observations are used for the GNSS RTS-IGS PPP model as the RTS-IGS satellite products are not available for BeiDou satellites. This paper provides the GNSS RTS-IGS PPP model using different satellite clock corrections namely: IGS01, IGC01, IGS01, and IGS03. All PPP models results of convergence time and positioning precision are compared to the traditional GPS-only PPP model. It is shown that combining GPS, Galileo, and BeiDou observations in a PPP model reduces the convergence time by 25 % compared with the GPS-only PPP model. Numéro de notice : A2016-974 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article DOI : 10.1515/jag-2016-0010 En ligne : https://doi.org/10.1515/jag-2016-0010 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=83681 [article]

Single-frequency precise point positioning using multi-constellation GNSS: GPS, Glonass, Galileo and Beidou / Mahmoud Abd Rabbou in Geomatica, vol 70 n° 2 (June 2016)  

Public [article]  inGeomatica > vol 70 n° 2 (June 2016) . - pp 113 - 122 Titre : Single-frequency precise point positioning using multi-constellation GNSS: GPS, Glonass, Galileo and Beidou Type de document : Article/Communication Auteurs : Mahmoud Abd Rabbou, Auteur ; Ahmed El-Rabbany, Auteur Année de publication : 2016 Article en page(s) : pp 113 - 122 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Navigation et positionnement [Termes IGN] constellation GNSS [Termes IGN] modèle ionosphérique [Termes IGN] positionnement par GNSS [Termes IGN] positionnement ponctuel précis Résumé : (auteur) Single-frequency precise point positioning (PPP) presents a cost-effective positioning technique for a large number of users. However, it possesses low positioning accuracy and convergence time compared with the dual-frequency PPP. Single-frequency PPP commonly employs GPS satellite systems that suffer from poor satellite geometry, especially in dense urban areas. We develop a new single-frequency PPP model that combines the observations of current GNSS constellations, including GPS, GLONASS, Galileo and Beidou. The MGEX IGS final precise products are utilized to account for the orbital and clock errors, while the IGS final global ionospheric maps (GIM) model is used to correct for the ionospheric delay. The GNSS inter-system biases are treated as additional unknowns in the estimation process. The contribution of the additional GNSS observations to single-frequency PPP is assessed through solution comparison with its traditional GPS-only counterpart. Various GNSS combinations are considered in the assessment, including GPS/GLONASS, GPS/Galileo, GPS/BeiDou and all-constellation GNSS. It is shown that the additional GNSS observations enhance the PPP solution accuracy and convergence time in comparison with the traditional GPS-only solution. Except for stations with a sufficient number of tracked BeiDou satellites, both Galileo and BeiDou have marginal effects on the positioning accuracy due to their limited number of satellites. However, for stations with a sufficient number of visible BeiDou satellites, an average of 40% PPP accuracy improvement is obtained. The major contribution to the PPP accuracy enhancement is obtained from GLONASS satellite observations. Numéro de notice : A2016-679 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article DOI : 10.5623/cig2016-203 En ligne : http://dx.doi.org/10.5623/cig2016-203 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=81933 [article]

Tightly coupled integration of GPS precise point positioning and MEMS-based inertial systems / Mahmoud Abd Rabbou in GPS solutions, vol 19 n° 4 (october 2015)  

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An improved between-satellite single-difference precise point positioning model for combined GPS/Galileo observations / Akram Afifi in Journal of applied geodesy, vol 9 n° 2 (June 2015)  

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An innovative dual frequency PPP model for combined GPS/Galileo observations / Akram Afifi in Journal of applied geodesy, vol 9 n° 1 (March 2015)  

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Performance analysis of GPS / GALILEO PPP model for static and kinematic applications / Mahmoud Abd-El-Rahman in Geomatica, vol 69 n° 1 (March 2015)  

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Precise point positioning using multi-constellation GNSS observations for kinematic applications / Mahmoud Abd-El-Rahman in Journal of applied geodesy, vol 9 n° 1 (March 2015)  

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Performance analysis of GPS/GLONASS precise point positioning / Mohamed Azab in Geomatica, vol 67 n° 4 (December 2013)  

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Performance evaluation of USTEC product for single-frequency precise point positioning / Mahmoud Abd-El-Rahman in Geomatica, vol 67 n° 4 (December 2013)  

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