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Kalman-filter-based undifferenced cycle slip estimation in real-time precise point positioning / Pan Li in GPS solutions, vol 23 n° 4 (October 2019)  

Public [article]  inGPS solutions > vol 23 n° 4 (October 2019) Titre : Kalman-filter-based undifferenced cycle slip estimation in real-time precise point positioning Type de document : Article/Communication Auteurs : Pan Li, Auteur ; Xinyuan Jiang, Auteur ; Xiaohong Zhang, Auteur ; et al., Auteur Année de publication : 2019 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie spatiale [Termes descripteurs IGN] filtre de Kalman [Termes descripteurs IGN] glissement de cycle [Termes descripteurs IGN] interruption du signal [Termes descripteurs IGN] mesurage de phase [Termes descripteurs IGN] modèle mathématique [Termes descripteurs IGN] positionnement cinématique [Termes descripteurs IGN] positionnement ponctuel précis [Termes descripteurs IGN] précision du positionnement [Termes descripteurs IGN] station GLONASS [Termes descripteurs IGN] station GPS [Termes descripteurs IGN] temps réel Résumé : (Auteur) Global navigation satellite system (GNSS) precise point positioning (PPP) requires continuous carrier-phase observations to achieve a solution of high precision. Precisely correcting cycle slips caused by signal interruptions is crucial for recovering the data continuity. Most of the existing approaches usually employ only data of one epoch after the interruption for real-time cycle slip processing. In this study, we propose to introduce and estimate cycle slip parameters together with standard PPP parameters, such as position, ionospheric delay, and ambiguities in the case that possible cycle slips are detected, using a Kalman-filter-based procedure with the undifferenced and uncombined PPP model. The integer search strategy is used to fix cycle slips. To reduce the probability of wrong integer fixing, a strict integer validation threshold is suggested. As a result, it is not easy to fix all cycle slips with only one epoch of data. Our approach can be easily extended to use multi-epoch observations to enhance the cycle slip estimation. Once the cycle slips are correctly determined, continuous PPP can be achieved instantaneously. This new approach is tested and validated with three groups of experiments using GPS and GLONASS stations operated by the International GNSS Service from DOY 1–10, 2017, and a real vehicle kinematic data. Numerous experimental results showed that the proposed method can correctly fix the cycle slips for more than 99.5% of epochs suffering from re-convergence. On average, this method takes observation information from about 1.5–2.5 epochs to fix cycle slips and realize rapid re-convergence. Consequently, positioning performance is significantly improved. Numéro de notice : A2019-334 Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s10291-019-0894-3 date de publication en ligne : 16/07/2019 En ligne : https://doi.org/10.1007/s10291-019-0894-3 Format de la ressource électronique : URL Article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=93423 [article]

Performance of Galileo-only dual-frequency absolute positioning using the fully serviceable Galileo constellation / Tomasz Hadas in GPS solutions, vol 23 n° 4 (October 2019)  

Public [article]  inGPS solutions > vol 23 n° 4 (October 2019) Titre : Performance of Galileo-only dual-frequency absolute positioning using the fully serviceable Galileo constellation Type de document : Article/Communication Auteurs : Tomasz Hadas, Auteur ; Kamil Kazmierski, Auteur ; Krzysztof Sosnica, Auteur Année de publication : 2019 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie spatiale [Termes descripteurs IGN] affaiblissement de la précision [Termes descripteurs IGN] analyse comparative [Termes descripteurs IGN] constellation Galileo [Termes descripteurs IGN] mesurage de phase [Termes descripteurs IGN] mesurage de pseudo-distance [Termes descripteurs IGN] phase [Termes descripteurs IGN] positionnement absolu [Termes descripteurs IGN] positionnement cinématique en temps réel [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) The recent development of the Galileo space segment and the accompanying support of the International GNSS Service (IGS) allows for worldwide Galileo-only positioning. In this study, different techniques of dual-frequency absolute positioning using the fully serviceable Galileo constellation are evaluated for the first time and compared to the performance of GPS positioning. The daily static positioning based on the broadcast ephemeris using Galileo pseudoranges is significantly more accurate than the corresponding GPS solutions, obtaining the accuracy of a few decimeters. In the kinematic mode, the accuracy is better than 10 m and 20 m for the horizontal and vertical components, respectively, which is comparable to that of GPS. Precise absolute positioning using pseudorange and carrier phase Galileo observations combined with IGS Real-Time Service (RTS) or Multi-GNSS Experiment products is not yet as good as the corresponding GPS solutions. In the static mode, the root mean squared error (RMSE) between estimated and reference coordinates does not exceed 0.05 m and 0.06 m for the horizontal and vertical components, respectively. In the kinematic mode, the respective accuracies are better than 0.17 m and 0.21 m. Moreover, we show that both GPS and Galileo pseudorange solutions benefit from the RTS when compared to the broadcast solutions with the improvement in the accuracy between 10 and 59%. Remarkable results are achieved for Galileo Precise Point Positioning (PPP) solutions based on the broadcast ephemeris. In the static mode, the RMSE is 0.07 and 0.10 m for the horizontal and vertical components which is three and two times better, respectively, then the corresponding solutions based on GPS. Numéro de notice : A2019-331 Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s10291-019-0900-9 date de publication en ligne : 07/08/2019 En ligne : https://doi.org/10.1007/s10291-019-0900-9 Format de la ressource électronique : URL Article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=93419 [article]

Consistency and analysis of ionospheric observables obtained from three precise point positioning models / Yan Xiang in Journal of geodesy, vol 93 n°8 (August 2019)  

Public [article]  inJournal of geodesy > vol 93 n°8 (August 2019) . - pp 1161–1170 Titre : Consistency and analysis of ionospheric observables obtained from three precise point positioning models Type de document : Article/Communication Auteurs : Yan Xiang, Auteur ; Yang Gao, Auteur ; Junbo Shi, Auteur ; Chaoqian Xu, Auteur Année de publication : 2019 Article en page(s) : pp 1161–1170 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie spatiale [Termes descripteurs IGN] analyse comparative [Termes descripteurs IGN] cohérence géométrique [Termes descripteurs IGN] erreur de positionnement [Termes descripteurs IGN] erreur en altitude [Termes descripteurs IGN] erreur systématique [Termes descripteurs IGN] mesurage de phase [Termes descripteurs IGN] modèle ionosphérique [Termes descripteurs IGN] positionnement différentiel [Termes descripteurs IGN] positionnement ponctuel précis [Termes descripteurs IGN] propagation ionosphérique Résumé : (auteur) Ionospheric observables based on Global Navigation Satellite System can be obtained by a variety of approaches. The most widely used one is the geometry-free combination of carrier-phase smoothed code measurements. This method, however, introduces leveling errors that substantially degrade the performance of ionospheric modeling and bias estimation. To reduce leveling errors, precise point positioning (PPP) model is preferred for obtaining the ionospheric observables. We aim to investigate whether the ionospheric observables obtained from three different PPP models are consistent and how the PPP-based ionospheric observables relates to the smoothed code method. The paper begins by formulating the ionospheric observables. We then explain the statistical evaluation methods used for analyzing the bias terms derived from these methods and assessing the leveling errors from the carrier-phase smoothed code method. Numerical analysis is then conducted to compare the bias terms in the ionospheric observables and evaluate the leveling errors. The ionospheric observables based on the three PPP models show strong consistency. Compared to leveling errors in the carrier-phase smoothed code method, the leveling errors using the uncombined PPP model are significantly reduced up to five times. Numéro de notice : A2019-384 Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-019-01233-1 date de publication en ligne : 12/02/2019 En ligne : https://doi.org/10.1007/s00190-019-01233-1 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=93463 [article]

Triple-frequency PPP ambiguity resolution with multi-constellation GNSS: BDS and Galileo / Xingxing Li in Journal of geodesy, vol 93 n°8 (August 2019)  

Public [article]  inJournal of geodesy > vol 93 n°8 (August 2019) . - pp 1105 - 1122 Titre : Triple-frequency PPP ambiguity resolution with multi-constellation GNSS: BDS and Galileo Type de document : Article/Communication Auteurs : Xingxing Li, Auteur ; Xin Li, Auteur ; Gege Liu, Auteur ; et al., Auteur Année de publication : 2019 Article en page(s) : pp 1105 - 1122 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Navigation et positionnement [Termes descripteurs IGN] ambiguïté entière [Termes descripteurs IGN] constellation BeiDou [Termes descripteurs IGN] constellation GNSS [Termes descripteurs IGN] estimation de position [Termes descripteurs IGN] fréquence multiple [Termes descripteurs IGN] mesurage de phase [Termes descripteurs IGN] positionnement cinématique [Termes descripteurs IGN] positionnement par Galileo [Termes descripteurs IGN] positionnement ponctuel précis [Termes descripteurs IGN] positionnement statique [Termes descripteurs IGN] résolution d'ambiguïté Résumé : (auteur) Multi-constellation GNSS (multi-GNSS) and multi-frequency signals open new prospects for fast ambiguity resolution (AR) of precise point positioning (PPP). Currently, all the BDS and Galileo satellites are capable of transmitting signals on three or more frequencies. In this contribution, we investigate the triple-frequency PPP ambiguity resolution with B1, B2 and B3 observations from BDS satellites and E1, E5a and E5b observations from Galileo satellites and evaluate the contribution of BDS + Galileo combination to triple-frequency PPP AR. The uncalibrated phase delay (UPD) products are estimated based on triple-frequency observations, and the temporal characteristic as well as the residual distributions are analyzed. Our results show that the extra-wide-lane (EWL) and wide-lane (WL) UPDs for BDS and Galileo satellites are both stable during the 30 days and the daily narrow-lane (NL) UPD series are also steady with no obvious fluctuation. The Galileo UPDs exhibit better performance than BDS UPDs due to the high-quality observations. It is also interesting to find that the EWL UPD corrections for all Galileo satellites are very close to the zero. With the precise UPD products, the triple-frequency PPP AR with BDS and Galileo observations was implemented in both static and kinematic modes. Compared to the ambiguity-float solution, the performance can be significantly improved by triple-frequency PPP AR with the positioning accuracy improved by 30–70% in both static and kinematic modes. Moreover, the triple-frequency PPP fixed solutions also present better performance than the dual-frequency PPP fixed solutions in terms of time to the first fix and positioning accuracy, especially for the Galileo-only and BDS + Galileo solutions. And the fusion of multi-GNSS (BDS and Galileo) can further improve the position estimations compared to the single system with more satellites and better spatial geometry. Numéro de notice : A2019-380 Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-019-01229-x date de publication en ligne : 01/02/2019 En ligne : https://doi.org/10.1007/s00190-019-01229-x Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=93457 [article]

Accuracy assessment of relative and precise point positioning online GPS processing services / Ahmed El Shouny in Journal of applied geodesy, vol 13 n° 3 (July 2019)  

Public [article]  inJournal of applied geodesy > vol 13 n° 3 (July 2019) . - pp 215 – 227 Titre : Accuracy assessment of relative and precise point positioning online GPS processing services Type de document : Article/Communication Auteurs : Ahmed El Shouny, Auteur ; Yehia Miky, Auteur Année de publication : 2019 Article en page(s) : pp 215 – 227 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Navigation et positionnement [Termes descripteurs IGN] Egypte [Termes descripteurs IGN] estimation de précision [Termes descripteurs IGN] positionnement différentiel [Termes descripteurs IGN] positionnement par GNSS [Termes descripteurs IGN] positionnement par GPS [Termes descripteurs IGN] positionnement ponctuel précis [Termes descripteurs IGN] traitement de données GNSS Résumé : (auteur) Over the last few years, several institutions, research centers, and organizations have developed different strategies for GPS data processing and analysis to obtain high accurate coordinates. They are taking into considerations overcoming restrictions and limitations such as necessity of using relative positioning, time consuming, and high cost of different processing software. One of these developed strategies is the web–based online GNSS (Global Navigation Satellite Systems) processing service which estimates coordinates with centimeter or decimeter level accuracy. This study aims to represent the most popular of these services, namely AUSPOS, OPUS, APPS, GAPS, Trimble RTX, and CSRS–PPP, also to perform in-between comparison of these services with respect to their achieved accuracy using field observations with different durations. The obtained results were compared with a real field data measured using traditional relative positioning technique with high accuracy standards. The set of data used in this study was performed in the Eastern zone in Egypt. The results of this comparison indicate that these services can be used as an alternative method for relative positioning technique due to their simplicity, cost-effective and saving in time. They saved about 75 % from the time required for traditional method to produce coordinate with reasonable accuracy. The maximum standard deviation obtained was 15.4 cm from APPS service with time less than two hours, while the minimum standard deviation was 0.07 cm and obtained from CSRS–PPP with time duration from 6 to 12 hours. For achieving more accurate results, it is recommended to use time duration more than two hours. Numéro de notice : A2019-285 Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1515/jag-2018-0046 date de publication en ligne : 24/04/2019 En ligne : https://doi.org/10.1515/jag-2018-0046 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=93120 [article]

Accuracy assessment of speed values calculated from GNSS tracks of roads obtained from VGI / Antonio Tomás Mozas-Calvache in Survey review, vol 51 n° 367 (July 2019)  

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Multi-GNSS real-time clock estimation using sequential least square adjustment with online quality control / Wenju Fu in Journal of geodesy, vol 93 n°7 (July 2019)  

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On the detectability of mis-modeled biases in the network-derived positioning corrections and their user impact / Amir Khodabandeh in GPS solutions, vol 23 n° 3 (July 2019)  

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Parallel computation of regional CORS network corrections based on ionospheric-free PPP / Linyang Li in GPS solutions, vol 23 n° 3 (July 2019)  

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PPP-RTK based on undifferenced and uncombined observations: theoretical and practical aspects / Baocheng Zhang in Journal of geodesy, vol 93 n°7 (July 2019)  

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Du NRTK vers le PPP-RTK, un exemple avec TERIA / Paul Chambon in XYZ, n° 159 (juin 2019)

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An improved robust Kalman filtering strategy for GNSS kinematic positioning considering small cycle slips / Wanke Liu in Advances in space research, vol 63 n° 9 (1 May 2019)  

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Assessing the latest performance of Galileo-only PPP and the contribution of Galileo to Multi-GNSS PPP / Fengyu Xiu in Advances in space research, vol 63 n° 9 (1 May 2019)  

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Les services Teria / Paul Chambon in Géomètre, n° 2168 (avril 2019)

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Teria : la géolocalisation de haute précision / Paul Chambon in Géomètre, n° 2168 (avril 2019)

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