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A method for improving uncalibrated phase delay estimation and ambiguity-fixing in real-time precise point positioning / Xinging Li in Journal of geodesy, vol 87 n° 5 (May 2013)  

Public [article]  inJournal of geodesy > vol 87 n° 5 (May 2013) . - pp 405 - 416 Titre : A method for improving uncalibrated phase delay estimation and ambiguity-fixing in real-time precise point positioning Type de document : Article/Communication Auteurs : Xinging Li, Auteur ; Maorong Ge, Auteur Année de publication : 2013 Article en page(s) : pp 405 - 416 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie spatiale [Termes IGN] ambiguïté entière [Termes IGN] atténuation du signal [Termes IGN] mesurage de phase [Termes IGN] positionnement ponctuel précis [Termes IGN] propagation ionosphérique [Termes IGN] résolution d'ambiguïté [Termes IGN] temps de propagation [Termes IGN] temps réel Résumé : (Auteur) In order to improve the performance of precise point positioning (PPP), this paper presents a new data processing scheme to shorten the convergence time and the observation time required for a reliable ambiguity-fixing. In the new scheme, L1 and L2 raw observations are used and the slant ionospheric delays are treated as unknown parameters. The empirical spatial and temporal constraints and the ionospheric delays derived from a real-time available ionospheric model are all considered as pseudo-observations into the estimation for strengthening the solution. Furthermore, we develop a real-time computational procedure for generating uncalibrated phase delays (UPDs) on L1 and L2 frequencies. The PPP solution is first carried out on all reference stations based on the proposed scheme, undifferenced float ambiguities on L1 and L2 frequencies can be directly obtained from the new scheme. The L1 and L2 UPDs are then generated and broadcasted to users in real-time. This data product and also the performance of the new PPP scheme are evaluated. Our results indicate that the new processing scheme considering ionospheric characteristics can reduce the convergence time by about 30 % for float kinematic solutions. The observation time for a reliable ambiguity-fixing is shortened by 25 % compared to that of the traditional ambiguity-fixed kinematic solution. When the new method is used for static reference stations, the observation time for ambiguity-fixing is about 10 min in static mode and only 5 min if the coordinates are fixed to well-known values. Numéro de notice : A2013-251 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-013-0611-x En ligne : https://doi.org/10.1007/s00190-013-0611-x Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=32389 [article]

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Analytical error analysis for satellite gravity field determination based on two-dimensional Fourier method / Lin Cai in Journal of geodesy, vol 87 n° 5 (May 2013)  

Public [article]  inJournal of geodesy > vol 87 n° 5 (May 2013) . - pp 417 - 426 Titre : Analytical error analysis for satellite gravity field determination based on two-dimensional Fourier method Type de document : Article/Communication Auteurs : Lin Cai, Auteur ; Zebing Zhou, Auteur ; Houste Hsu, Auteur ; et al., Auteur Année de publication : 2013 Article en page(s) : pp 417 - 426 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie physique [Termes IGN] champ de pesanteur terrestre [Termes IGN] densité spectrale de puissance [Termes IGN] erreur de positionnement [Termes IGN] gravimétrie spatiale [Termes IGN] harmonique sphérique [Termes IGN] levé gravimétrique [Termes IGN] modèle de géopotentiel Résumé : (Auteur) The time-wise and space-wise approaches are generally applied to data processing and error analysis for satellite gravimetry missions. But both the approaches, which are based on least-squares method, address the whole effect of measurement errors and estimate the resolution of gravity field models mainly from a numerical point of view. Moreover, requirement for higher accuracy and resolution gravity field models could make the computation more difficult, and serious numerical instabilities arise. A direct analytical expression between power spectral density of the satellite gravimetry measurements and spherical harmonic coefficients of the Earth’s gravity model is derived based on two-dimensional Fourier description. This method provides a physical insight into the relation between mission parameters, instrument parameters and gravity field parameters. In contrast, the least-squares method is mainly based on a mathematical viewpoint. By taking advantage of the analytical expression, it is efficient and distinct for parameter estimation and error analysis of missions. It is easy to obtain from the analytical relationship that the low-frequency noise affects the gravity field recovery in all degrees for the instance of satellite gradiometer recovery mission, which agrees with the work before by the numerical error analysis methods Numéro de notice : A2013-252 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-013-0615-6 Date de publication en ligne : 03/02/2013 En ligne : https://doi.org/10.1007/s00190-013-0615-6 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=32390 [article]

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Stochastic modeling of high-stability ground clocks in GPS analysis / Kang Wang in Journal of geodesy, vol 87 n° 5 (May 2013)  

Public [article]  inJournal of geodesy > vol 87 n° 5 (May 2013) . - pp 427 - 437 Titre : Stochastic modeling of high-stability ground clocks in GPS analysis Type de document : Article/Communication Auteurs : Kang Wang, Auteur ; Markus Rothacher, Auteur Année de publication : 2013 Article en page(s) : pp 427 - 437 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie spatiale [Termes IGN] horloge atomique [Termes IGN] modèle stochastique [Termes IGN] positionnement cinématique [Termes IGN] positionnement ponctuel précis [Termes IGN] propagation troposphérique [Termes IGN] signal GPS [Termes IGN] stabilité [Termes IGN] temps atomique international Résumé : (Auteur) In current global positioning system (GPS) applications, receiver clocks are typically estimated epoch-wise in the data analyses even for clocks with high performance like Hydrogen-masers (H-maser). Applying an appropriate clock model for high-stability receiver clocks should, in view of the strong correlation between the station height and the clock parameters, significantly improve the positioning results. Recent experiments have shown that modeling the deterministic behavior of high-quality receiver clocks can improve the kinematic precise point positioning considerably. In this paper, well-behaving ground clocks are studied in detail applying constraints between subsequent and near-subsequent clock parameters. The influence of different weights for these relative clock constraints on the positioning quality, especially on the height, is investigated. For excellent clocks, an improvement of up to a factor of 3 can be obtained for the repeatability of the kinematic height estimates. This may be essential to detect small but sudden changes in the vertical component (e.g., caused by earthquakes). Troposphere zenith path delays (ZPD) are also heavily correlated with the receiver clock estimates and station heights. All these parameters are usually estimated simultaneously. We show that the use of relative clock constraints allows for a higher time resolution of the ZPD estimates (smaller than 2 h) without compromising the quality of the kinematic height estimates. Numéro de notice : A2013-253 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-013-0616-5 Date de publication en ligne : 19/03/2013 En ligne : https://doi.org/10.1007/s00190-013-0616-5 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=32391 [article]

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Global empirical model for mapping zenith wet delays onto precipitable water / Yi Bin Yao in Journal of geodesy, vol 87 n° 5 (May 2013)  

Public [article]  inJournal of geodesy > vol 87 n° 5 (May 2013) . - pp 439 - 448 Titre : Global empirical model for mapping zenith wet delays onto precipitable water Type de document : Article/Communication Auteurs : Yi Bin Yao, Auteur ; Bao Zhang, Auteur ; Shun Qiang Yue, Auteur ; et al., Auteur Année de publication : 2013 Article en page(s) : pp 439 - 448 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Applications de géodésie spatiale [Termes IGN] propagation du signal [Termes IGN] radiosondage [Termes IGN] température au sol [Termes IGN] température de surface de la mer [Termes IGN] vapeur d'eau Résumé : (Auteur) We can map zenith wet delays onto precipitable water with a conversion factor, but in order to calculate the exact conversion factor, we must precisely calculate its key variable Tm . Yao et al. (J Geod 86:1125–1135, 2012. doi:10.1007/s00190-012-0568-1) established the first generation of global Tm model (GTm-I) with ground-based radiosonde data, but due to the lack of radiosonde data at sea, the model appears to be abnormal in some areas. Given that sea surface temperature varies less than that on land, and the GPT model and the Bevis Tm – Ts relationship are accurate enough to describe the surface temperature and Tm , this paper capitalizes on the GPT model and the Bevis Tm – Ts relationship to provide simulated Tm at sea, as a compensation for the lack of data. Combined with the Tm from radiosonde data, we recalculated the GTm model coefficients. The results show that this method not only improves the accuracy of the GTm model significantly at sea but also improves that on land, making the GTm model more stable and practically applicable. Numéro de notice : A2013-254 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-013-0617-4 Date de publication en ligne : 20/02/2013 En ligne : https://doi.org/10.1007/s00190-013-0617-4 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=32392 [article]

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Triple-frequency GPS precise point positioning with rapid ambiguity resolution / Jianghui Geng in Journal of geodesy, vol 87 n° 5 (May 2013)  

Public [article]  inJournal of geodesy > vol 87 n° 5 (May 2013) . - 460 p. ; pp 449 - 460 Titre : Triple-frequency GPS precise point positioning with rapid ambiguity resolution Type de document : Article/Communication Auteurs : Jianghui Geng, Auteur ; Yehuda Bock, Auteur Année de publication : 2013 Article en page(s) : 460 p. ; pp 449 - 460 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie spatiale [Termes IGN] modulation de fréquence [Termes IGN] positionnement ponctuel précis [Termes IGN] récepteur trifréquence [Termes IGN] résolution d'ambiguïté Résumé : (Auteur) At present, reliable ambiguity resolution in real-time GPS precise point positioning (PPP) can only be achieved after an initial observation period of a few tens of minutes. In this study, we propose a method where the incoming triple-frequency GPS signals are exploited to enable rapid convergences to ambiguity-fixed solutions in real-time PPP. Specifically, extra-wide-lane ambiguity resolution can be first achieved almost instantaneously with the Melbourne-Wübbena combination observable on L2 and L5. Then the resultant unambiguous extra-wide-lane carrier-phase is combined with the wide-lane carrier-phase on L1 and L2 to form an ionosphere-free observable with a wavelength of about 3.4 m. Although the noise of this observable is around 100 times the raw carrier-phase noise, its wide-lane ambiguity can still be resolved very efficiently, and the resultant ambiguity-fixed observable can assist much better than pseudorange in speeding up succeeding narrow-lane ambiguity resolution. To validate this method, we use an advanced hardware simulator to generate triple-frequency signals and a high-grade receiver to collect 1-Hz data. When the carrier-phase precisions on L1, L2 and L5 are as poor as 1.5, 6.3 and 1.5 mm, respectively, wide-lane ambiguity resolution can still reach a correctness rate of over 99 % within 20 s. As a result, the correctness rate of narrow-lane ambiguity resolution achieves 99 % within 65 s, in contrast to only 64 % within 150 s in dual-frequency PPP. In addition, we also simulate a multipath-contaminated data set and introduce new ambiguities for all satellites every 120 s. We find that when multipath effects are strong, ambiguity-fixed solutions are achieved at 78 % of all epochs in triple-frequency PPP whilst almost no ambiguities are resolved in dual-frequency PPP. Therefore, we demonstrate that triple-frequency PPP has the potential to achieve ambiguity-fixed solutions within a few minutes, or even shorter if raw carrier-phase precisions are around 1 mm. In either case, we conclude that the efficiency of ambiguity resolution in triple-frequency PPP is much higher than that in dual-frequency PPP. Numéro de notice : A2013-255 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-013-0619-2 Date de publication en ligne : 22/02/2013 En ligne : https://doi.org/10.1007/s00190-013-0619-2 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=32393 [article]

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Initial results of precise orbit and clock determination for COMPASS navigation satellite system / Qile Zhao in Journal of geodesy, vol 87 n° 5 (May 2013)  

Public [article]  inJournal of geodesy > vol 87 n° 5 (May 2013) . - pp 475 - 486 Titre : Initial results of precise orbit and clock determination for COMPASS navigation satellite system Type de document : Article/Communication Auteurs : Qile Zhao, Auteur ; Jing Guo, Auteur ; Min Li, Auteur Année de publication : 2013 Article en page(s) : pp 475 - 486 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie spatiale [Termes IGN] BeiDou [Termes IGN] orbitographie [Termes IGN] positionnement cinématique [Termes IGN] positionnement ponctuel précis [Termes IGN] positionnement statique Résumé : (Auteur) The development of the COMPASS satellite system is introduced, and the regional tracking network and data availability are described. The precise orbit determination strategy of COMPASS satellites is presented. Data of June 2012 are processed. The obtained orbits are evaluated by analysis of post-fit residuals, orbit overlap comparison and SLR (satellite laser ranging) validation. The RMS (root mean square) values of post-fit residuals for one month’s data are smaller than 2.0 cm for ionosphere-free phase measurements and 2.6 m for ionosphere-free code observations. The 48-h orbit overlap comparison shows that the RMS values of differences in the radial component are much smaller than 10 cm and those of the cross-track component are smaller than 20 cm. The SLR validation shows that the overall RMS of observed minus computed residuals is 68.5 cm for G01 and 10.8 cm for I03. The static and kinematic PPP solutions are produced to further evaluate the accuracy of COMPASS orbit and clock products. The static daily COMPASS PPP solutions achieve an accuracy of better than 1 cm in horizontal and 3 cm in vertical. The accuracy of the COMPASS kinematic PPP solutions is within 1–2 cm in the horizontal and 4–7 cm in the vertical. In addition, we find that the COMPASS kinematic solutions are generally better than the GPS ones for the selected location. Furthermore, the COMPASS/GPS combinations significantly improve the accuracy of GPS only PPP solutions. The RMS values are basically smaller than 1 cm in the horizontal components and 3–4 cm in the vertical component. Numéro de notice : A2013-256 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-013-0622-7 Date de publication en ligne : 28/02/2013 En ligne : https://doi.org/10.1007/s00190-013-0622-7 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=32394 [article]

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