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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 descripteurs IGN] coordonnées GPS [Termes descripteurs IGN] données BeiDou [Termes descripteurs IGN] krigeage [Termes descripteurs IGN] méthode des moindres carrés [Termes descripteurs IGN] modèle ionosphérique [Termes descripteurs IGN] positionnement ponctuel précis [Termes descripteurs IGN] simple différence [Termes descripteurs IGN] station de référence [Termes descripteurs 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 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 descripteurs IGN] combinaison au niveau des observations [Termes descripteurs IGN] performance [Termes descripteurs IGN] positionnement par BeiDou [Termes descripteurs IGN] positionnement par Galileo [Termes descripteurs IGN] positionnement par GLONASS [Termes descripteurs IGN] positionnement par GNSS [Termes descripteurs IGN] positionnement par GPS [Termes descripteurs IGN] positionnement ponctuel précis [Termes descripteurs IGN] positionnement statique [Termes descripteurs IGN] précision du positionnement [Termes descripteurs 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 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 descripteurs IGN] erreur de positionnement [Termes descripteurs IGN] erreur systématique [Termes descripteurs IGN] milieu urbain [Termes descripteurs IGN] modèle mathématique [Termes descripteurs IGN] positionnement par BeiDou [Termes descripteurs IGN] positionnement par Galileo [Termes descripteurs IGN] positionnement par GNSS [Termes descripteurs IGN] positionnement par GPS [Termes descripteurs IGN] positionnement ponctuel précis [Termes descripteurs IGN] récepteur bifréquence [Termes descripteurs 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 Thématique : POSITIONNEMENT Nature : Article 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 [en ligne], vol 70 n° 2 (June 2016)  

Public [article]  inGeomatica [en ligne] > 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 descripteurs IGN] constellation GNSS [Termes descripteurs IGN] modèle ionosphérique [Termes descripteurs IGN] positionnement par GNSS [Termes descripteurs 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 Thématique : POSITIONNEMENT Nature : Article 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)  

Public [article]  inGPS solutions > vol 19 n° 4 (october 2015) . - pp 601 - 609 Titre : Tightly coupled integration of GPS precise point positioning and MEMS-based inertial systems Type de document : Article/Communication Auteurs : Mahmoud Abd Rabbou, Auteur ; Ahmed El-Rabbany, Auteur Année de publication : 2015 Article en page(s) : pp 601 - 609 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie spatiale [Termes descripteurs IGN] centrale inertielle [Termes descripteurs IGN] filtre de Kalman [Termes descripteurs IGN] GPS-INS [Termes descripteurs IGN] implémentation (informatique) [Termes descripteurs IGN] Matlab [Termes descripteurs IGN] microsystème électromécanique [Termes descripteurs IGN] positionnement par GPS [Termes descripteurs IGN] positionnement ponctuel précis [Termes descripteurs IGN] simple différence Résumé : (auteur) We develop a new integrated navigation system, which integrates GPS precise point positioning (PPP) with low-cost micro-electro-mechanical sensors (MEMS) inertial system, for precise positioning applications. Currently, most common GPS PPP techniques employ undifferenced ionosphere-free (IF) linear combination. In this work, both undifferenced and between-satellite single-difference (BSSD) IF linear combinations of pseudorange and carrier measurements are considered. IGS precise orbital and clock products are used to correct for satellite orbit and clock errors. Rigorous models are used to account for tropospheric delay, ocean loading, earth tide, carrier phase windup, relativity and satellite antenna phase-center variations. To integrate GPS PPP and MEMS-based inertial systems, the process and measurement models are developed. Tightly coupled mechanization is adopted, which is carried out in the raw measurements domain. Extended Kalman filter is developed to merge the corrected GPS satellite difference observations and inertial measurements and estimate inertial measurements biases and errors. A atlab-based computer program is developed to carry out the tightly coupled integration. The performance of the proposed integrated system is analyzed using a real test situation. It is shown that decimeter-level positioning accuracy is achievable with both undifferenced and BSSD integrated systems. However, in general, better positioning accuracy is obtained with BSSD integrated system. Numéro de notice : A2015-467 Thématique : POSITIONNEMENT Nature : Article En ligne : http://link.springer.com/article/10.1007/s10291-014-0415-3/fulltext.html Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=77155 [article]

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 [en ligne], 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 [en ligne], 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 [en ligne], vol 67 n° 4 (December 2013)

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