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Identifying a low-frequency oscillation in Galileo IOV pseudorange rates / Daniele Borio in GPS solutions, vol 20 n° 3 (July 2016)
[article]
Titre : Identifying a low-frequency oscillation in Galileo IOV pseudorange rates Type de document : Article/Communication Auteurs : Daniele Borio, Auteur ; Ciro Gioia, Auteur ; Neil Mitchison, Auteur Année de publication : 2016 Article en page(s) : pp 363 - 372 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie spatiale
[Termes IGN] étalonnage en vol
[Termes IGN] Galileo
[Termes IGN] horloge atomique
[Termes IGN] mesurage de pseudo-distance
[Termes IGN] oscillateur
[Termes IGN] performance
[Termes IGN] vitesseRésumé : (Auteur) Galileo, the European global navigation satellite system, is in its in-orbit validation phase and the four satellites which have been available for some months now have allowed a preliminary analysis of the system performance. Previous studies have showed that Galileo will be able to provide pseudorange measurements more accurate than those provided by GPS. However, a similar improvement was not found for pseudorange rate observations in the velocity domain. This fact stimulated additional analysis of the velocity domain, and, in particular, an unintended oscillatory component was identified as the main error source in the velocity solution. The magnitude of such oscillation is less than 10 cm/s, and its period is in the order of few minutes. A methodology was developed to identify oscillatory components in the Galileo IOV pseudorange rate observables, and it was verified that the measurements from Galileo IOV PFM and Galileo IOV FM2 are affected by a small oscillatory disturbance. This disturbance stems from the architecture adopted for combining the frequency references provided by the two active clocks present in the Galileo satellites. The issue has been solved in Galileo IOV FM3 and Galileo IOV FM4, and the oscillatory component has been eliminated. We also propose a methodology for removing this unwanted component from the final velocity solution and for determining the performance that Galileo will be able to achieve. The analysis shows that Galileo velocity solution will provide a root-mean-square error of about 8 cm/s even in the limited geometry conditions achieved using only four satellites. This shows the potential of Galileo also in the determination of user velocity. Numéro de notice : A2016-630 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article DOI : 10.1007/s10291-015-0443-7 En ligne : http://dx.doi.org/10.1007/s10291-015-0443-7 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=81833
in GPS solutions > vol 20 n° 3 (July 2016) . - pp 363 - 372[article]Performance of real-time Precise Point Positioning using IGS real-time service / Mohamed Elsobeiey in GPS solutions, vol 20 n° 3 (July 2016)
[article]
Titre : Performance of real-time Precise Point Positioning using IGS real-time service Type de document : Article/Communication Auteurs : Mohamed Elsobeiey, Auteur ; Salim Al-Harbi, Auteur Année de publication : 2016 Article en page(s) : pp 565 - 571 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Navigation et positionnement
[Termes IGN] correction du signal
[Termes IGN] horloge
[Termes IGN] international GPS service for geodynamics
[Termes IGN] orbite
[Termes IGN] positionnement ponctuel précis
[Termes IGN] temps réelRésumé : (Auteur) Until recently, the real-time IGS precise orbit and clock corrections were only available for the predicted part of the ultra-rapid solution. Whereas the accuracy of the ultra-rapid orbit is about 5 cm, the root mean square (RMS) of the respective satellite clock corrections is, unfortunately, about 3 ns (0.9 m). Hence, high accuracy Precise Point Positioning (PPP) applications can be achieved only in post-processing rather than in realtime. With the availability of the IGS real-time service (RTS), it becomes possible to obtain precise satellite orbit and satellite clock corrections in realtime with accuracy better than those of the ultra-rapid products. Recent research has shown that GPS IGS RTS products availability is at least 95 %, which makes it possible to perform real-time PPP with high accuracy. We study the performance of IGS RTS products in PPP by introducing a detailed description and analysis of IGS RTS products, describing the broadcasting of the IGS RTS orbit and clock corrections and their implementation as corrections to the broadcast ephemerides, and analyzing IGS RTS in PPP using several, randomly selected globally distributed IGS stations. It is shown that using IGS RTS products in real-time PPP can improve the solution RMS by about 50 % compared with the solution obtained from the predicted part of the IGS ultra-rapid products. Numéro de notice : A2016-635 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article DOI : 10.1007/s10291-015-0467-z En ligne : http://dx.doi.org/10.1007/s10291-015-0467-z Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=81837
in GPS solutions > vol 20 n° 3 (July 2016) . - pp 565 - 571[article]Potential of GPS common clock single-differences for deformation monitoring / Steffen Schön in Journal of applied geodesy, vol 10 n° 1 (March 2016)
[article]
Titre : Potential of GPS common clock single-differences for deformation monitoring Type de document : Article/Communication Auteurs : Steffen Schön, Auteur ; Hue Kiem Pham, Auteur ; Tobias Kersten, Auteur ; Julia Leute, Auteur ; Andreas Bauch, Auteur Année de publication : 2016 Article en page(s) : pp 45 - 52 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Termes IGN] déformation géométrique
[Termes IGN] hauteur ellipsoïdale
[Termes IGN] horloge
[Termes IGN] positionnement cinématique
[Termes IGN] récepteur GNSS
[Termes IGN] simple différence
[Vedettes matières IGN] Traitement de données GNSSRésumé : (auteur) Global satellite navigation systems (GNSS) are a standard measurement device for deformation monitoring. In many applications, double-differences are used to reduce distance dependent systematic effects, as well as to eliminate the receiver and satellites clock errors. However, due to the navigation principle of one way ranging used in GPS, the geometry of the subsequent adjustment is weakened. As a result, the height component is generally determined three times less precisely than the horizontal coordinates. In addition, large correlations between the height and elevation dependent effects exist such as tropospheric refraction, mismodelled phase center variations, or multipath which restricts the attainable accuracy. However, for a kinematic analysis, i. e. for estimating high rate coordinate time series, the situation can be significantly improved if a common clock is connected to different GNSS receivers in a network or on a baseline. Consequently, between-station single-differences are sufficient to solve for the baseline coordinates. The positioning geometry is significantly improved which is reflected by a reduction of the standard deviation of kinematic heights by about a factor 3 underlining the benefits of this new approach. Real data from baselines at the Physikalisch-Technische Bundesanstalt campus at Braunschweig where receivers are connected over 290 m via an optical fiber link to a common clock was analysed. Numéro de notice : A2016-553 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article DOI : 10.1515/jag-2015-0029 En ligne : http://dx.doi.org/10.1515/jag-2015-0029 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=81700
in Journal of applied geodesy > vol 10 n° 1 (March 2016) . - pp 45 - 52[article]
Titre : Advanced modeling and algorithms for high-precision GNSS analysis Type de document : Thèse/HDR Auteurs : Kan Wang, Auteur Editeur : Zurich : Eidgenossische Technische Hochschule ETH - Ecole Polytechnique Fédérale de Zurich EPFZ Année de publication : 2016 Collection : Dissertationen ETH num. 23188 Note générale : bibliographie
thesis submitted to attain the degree of doctor of sciences of ETH ZurichLangues : Anglais (eng) Descripteur : [Termes IGN] ambiguïté entière
[Termes IGN] antenne GPS
[Termes IGN] centre de phase
[Termes IGN] données BeiDou
[Termes IGN] données Galileo
[Termes IGN] données GPS
[Termes IGN] double différence
[Termes IGN] erreur systématique
[Termes IGN] GPS en mode différentiel
[Termes IGN] horloge
[Termes IGN] phase GNSS
[Termes IGN] positionnement cinématique
[Termes IGN] récepteur GNSS
[Termes IGN] récepteur trifréquence
[Termes IGN] résolution d'ambiguïté
[Termes IGN] retard ionosphèrique
[Termes IGN] Suisse
[Termes IGN] trajet multiple
[Vedettes matières IGN] Traitement de données GNSSRésumé : (auteur) In the recent ten years, the Global Navigation Satellite System (GNSS) processing has experienced a fast development in many areas including the increasing number of frequencies, the higher quality of positioning instruments, e.g. the receiver clocks and the satellite clocks, and more integrated modeling and calculation strategies. This thesis includes investigations of different modeling and parameterization methods in modern GNSS positioning with the focus on three important positioning error sources: the receiver clock errors, the phase ambiguities and the ionospheric delays.
The thesis shows that making use of the high-quality receiver clocks and applying appropriate receiver clock modeling can help to improve the kinematic height estimates, which are highly correlated with the receiver clock parameters. An efficient pre-elimination and back-substitution strategy of epoch parameters with relative clock constraints between subsequent and near-subsequent epochs has been developed to enable processing of, e.g., high-rate data. A detailed analysis of the relationship between the clock quality and the improvement of kinematic heights has been performed. Studies were also conducted to decorrelate the receiver clock parameters, the kinematic heights and the troposphere parameters. Experiments with real data have shown that appropriate deterministic and stochastic clock models can also be helpful to increase the resolution of the estimated Zenith Path Delay (ZPD) parameters without obvious degradation of the stability of the kinematic heights.
The second aspect of the thesis focuses on the resolution of triple-frequency phase ambiguities with different linear combinations. A complete analytical investigation of Geometry-Free (GF) and Ionosphere-Free (IF) triple-frequency phase ambiguity resolution with minimized noise level has been performed for different frequency triplets. The analysis was done separately for the best two linear combinations and the third one. Experiments have shown that the fractional parts and the formal errors of the combined ambiguities of the best two linear combinations are relatively small for Galileo E1, E5b and E5a and GPS L1, L2 and L5 triplets, while the third linear combination remains a challenge. Further analysis with the geostationary satellites of the Beidou Navigation Satellite System (BDS) elaborated in the framework of this thesis has also confirmed that the combined ambiguities from the best two GF and IF linear combinations can be fixed by rounding, while the estimated ambiguities on L1 have relatively large deviations from the values obtained from the traditional dual-frequency double-difference ambiguity resolution. Apart from the triple-frequency ambiguity resolution on the double-difference level, the so-called track-to-track ambiguities between different tracks of the same receiver and the same satellite have also been investigated for the best two triple-frequency linear combinations using GPS L1, L2 and L5 as well as Galileo E1, E5b and E5a observations. The outcome demonstrates that elevation-dependent influences on the observations like Phase Center Variations (PCVs), Phase Center Offsets (PCOs) and multipath are important for the fixing of the track-to-track ambiguities.
The combined track-to-track ambiguities using the best two linear combinations are also effective in detecting problems in the observation data.
The third aspect of the thesis includes the investigation of the differential ionospheric delays and gradients in the region of Switzerland from 1999 to 2013. In differential Global Positioning System (GPS) positioning, the ionospheric delays for short baselines are in most cases small enough to be ignored, except under extreme conditions, e.g., during ionospheric stormy days, and for applications with high integrity requirements, e.g., during approach and landing of aircrafts. This thesis introduces an algorithm using double-difference phase measurements with resolved phase ambiguities and global ionosphere maps provided by the Center for Orbit Determination in Europe (CODE) to extract the single-difference ionospheric delays, and enabling an automatic and robust processing of the data over 15 years. The results show that the daily maximum slant ionospheric gradients calculated from the differential slant ionopheric delays and the baseline lengths from 1999 to 2013 are below the slant ionosphere gradient boundary of the Conterminous United States (CONUS) ionospheric anomaly threat model.Numéro de notice : 17250 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Thèse étrangère Note de thèse : dissertation : sciences : ETH Zurich : 2016 En ligne : http://dx.doi.org/10.3929/ethz-a-010610972 Format de la ressource électronique : URL Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=81986 Impacts of real-time satellite clock errors on GPS precise point positioning-based troposphere zenith delay estimation / Junbo Shi in Journal of geodesy, vol 89 n° 8 (August 2015)
[article]
Titre : Impacts of real-time satellite clock errors on GPS precise point positioning-based troposphere zenith delay estimation Type de document : Article/Communication Auteurs : Junbo Shi, Auteur ; Chaoqian Xu, Auteur ; Yihe Li, Auteur ; Yang Gao, Auteur Année de publication : 2015 Article en page(s) : pp 747-756 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Termes IGN] erreur corrélée au temps
[Termes IGN] horloge atomique
[Termes IGN] orbite précise
[Termes IGN] positionnement cinématique en temps réel
[Termes IGN] positionnement par GPS
[Termes IGN] positionnement ponctuel précis
[Termes IGN] retard troposphérique zénithal
[Termes IGN] temps réel
[Vedettes matières IGN] Traitement de données GNSSRésumé : (auteur) Global Positioning System (GPS) has become a cost-effective tool to determine troposphere zenith total delay (ZTD) with accuracy comparable to other atmospheric sensors such as the radiosonde, the water vapor radiometer, the radio occultation and so on. However, the high accuracy of GPS troposphere ZTD estimates relies on the precise satellite orbit and clock products available with various latencies. Although the International GNSS Service (IGS) can provide predicted orbit and clock products for real-time applications, the predicted clock accuracy of 3 ns cannot always guarantee the high accuracy of troposphere ZTD estimates. Such limitations could be overcome by the use of the newly launched IGS real-time service which provides ∼5 cm orbit and 0.2–1.0 ns (an equivalent range error of 6–30 cm) clock products in real time. Considering the relatively larger magnitude of the clock error than that of the orbit error, this paper investigates the effect of real-time satellite clock errors on the GPS precise point positioning (PPP)-based troposphere ZTD estimation. Meanwhile, how the real-time satellite clock errors impact the GPS PPP-based troposphere ZTD estimation has also been studied to obtain the most precise ZTD solutions. First, two types of real-time satellite clock products are assessed with respect to the IGS final clock product in terms of accuracy and precision. Second, the real-time GPS PPP-based troposphere ZTD estimation is conducted using data from 34 selected IGS stations over three independent weeks in April, July and October, 2013. Numerical results demonstrate that the precision, rather than the accuracy, of the real-time satellite clock products impacts the real-time PPP-based ZTD solutions more significantly. In other words, the real-time satellite clock product with better precision leads to more precise real-time PPP-based troposphere ZTD solutions. Therefore, it is suggested that users should select and apply real-time satellite products with better clock precision to obtain more consistent real-time PPP-based ZTD solutions. Numéro de notice : A2015-374 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-015-0811-7 Date de publication en ligne : 04/04/2015 En ligne : https://doi.org/10.1007/s00190-015-0811-7 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=76852
in Journal of geodesy > vol 89 n° 8 (August 2015) . - pp 747-756[article]Single-frequency precise point positioning: an analytical approach / Oskar Sterle in Journal of geodesy, vol 89 n° 8 (August 2015)PermalinkThe clock at the center of the universe / Gavin Schrock in xyHt, vol 2015 n° 6 (June 2015)PermalinkEstimating the short-term stability of in-orbit GNSS clocks : Following launch on GEO/GSO satellites / Dhaval Upadhyay in Inside GNSS, vol 10 n° 3 (May - June 2015)PermalinkReal-time clock jump compensation for precise point positioning / Fei Guo in GPS solutions, vol 18 n° 1 (january 2014)PermalinkCalibration of the clock-phase biases of GNSS networks: the closure-ambiguity approach / A. Lannes in Journal of geodesy, vol 87 n° 8 (August 2013)PermalinkStochastic modeling of high-stability ground clocks in GPS analysis / Kang Wang in Journal of geodesy, vol 87 n° 5 (May 2013)PermalinkLe positionnement par satellites et les maths / Jonathan Chenal in Tangente, n° 151 (mars-avril 2013)PermalinkPerformance of real-time precise point positioning / Junping Chen in Marine geodesy, vol 36 n° 1 (January - March 2013)PermalinkTime, atomics clocks and relativistic geodesy / Enrico Mai (2013)PermalinkGalileo, un système global de positionnement par satellites / Jonathan Chenal (2012)Permalink