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Regional reference network augmented precise point positioning for instantaneous ambiguity resolution / X. Li in Journal of geodesy, vol 85 n° 3 (March 2011)  

Public [article]  inJournal of geodesy > vol 85 n° 3 (March 2011) . - pp 151 - 158 Titre : Regional reference network augmented precise point positioning for instantaneous ambiguity resolution Type de document : Article/Communication Auteurs : X. Li, Auteur ; X. Zhang, Auteur ; M. Ge, Auteur Année de publication : 2011 Article en page(s) : pp 151 - 158 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie spatiale [Termes descripteurs IGN] ambiguïté entière [Termes descripteurs IGN] positionnement cinématique en temps réel [Termes descripteurs IGN] positionnement ponctuel précis [Termes descripteurs IGN] réseau géodésique local [Termes descripteurs IGN] résolution d'ambiguïté Résumé : (Auteur) Integer ambiguity fixing can significantly shorten the initialization time and improve the accuracy of precise point positioning (PPP), but it still takes approximate 15 min of time to achieve reliable integer ambiguity solutions. In this contribution, we present a new strategy to augment PPP estimation with a regional reference network, so that instantaneous ambiguity fixing is achievable for users within the network coverage. In the proposed method, precise zero-differenced atmospheric delays are derived from the PPP fixed solution of the reference stations, which are disseminated to, and interpolated at user stations to correct for L1, L2 phase observations or their combinations. With the corrected observations, instantaneous ambiguity resolution can be carried out within the user PPP software, thus achieving the position solutions equivalent to the network real-time kinematic positioning (NRTK). The strategy is validated experimentally. The derived atmospheric delays and the interpolated corrections are investigated. The ambiguity fixing performance and the resulted position accuracy are assessed. The validation confirms that the new strategy can provide comparable service with NRTK. Therefore, with this new processing strategy, it is possible to integrate PPP and NRTK into a seamless positioning service, which can provide an accuracy of about 10 cm anywhere, and upgrade to a few centimeters within a regional network. Numéro de notice : A2011-164 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-010-0424-0 date de publication en ligne : 23/11/2010 En ligne : https://doi.org/10.1007/s00190-010-0424-0 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=30942 [article]

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Rapid re-convergences to ambiguity-fixed solutions in precise point positioning / J. Geng in Journal of geodesy, vol 84 n° 12 (December 2010)  

Public [article]  inJournal of geodesy > vol 84 n° 12 (December 2010) . - 10 p. ; pp 705 - 714 Titre : Rapid re-convergences to ambiguity-fixed solutions in precise point positioning Type de document : Article/Communication Auteurs : J. Geng, Auteur ; X. Meng, Auteur ; A. Dodson, Auteur ; et al., Auteur Année de publication : 2010 Article en page(s) : 10 p. ; pp 705 - 714 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Navigation et positionnement [Termes descripteurs IGN] ambiguïté entière [Termes descripteurs IGN] convergence [Termes descripteurs IGN] correction ionosphérique [Termes descripteurs IGN] positionnement par GPS [Termes descripteurs IGN] positionnement ponctuel précis [Termes descripteurs IGN] propagation ionosphérique [Termes descripteurs IGN] résolution d'ambiguïté [Termes descripteurs IGN] Suisse [Termes descripteurs IGN] temps réel Résumé : (Auteur) Integer ambiguity resolution at a single receiver can be achieved if the fractional-cycle biases are separated from the ambiguity estimates in precise point positioning (PPP). Despite the improved positioning accuracy by such integer resolution, the convergence to an ambiguity-fixed solution normally requires a few tens of minutes. Even worse, these convergences can repeatedly occur on the occasion of loss of tracking locks for many satellites if an open sky-view is not constantly available, consequently totally destroying the practicability of real-time PPP. In this study, in case of such re-convergences, we develop a method in which ionospheric delays are precisely predicted to significantly accelerate the integer ambiguity resolution. The effectiveness of this method consists in two aspects: first, wide-lane ambiguities can be rapidly resolved using the ionosphere-corrected wide-lane measurements, instead of the noisy Melbourne–Wübbena combination measurements; second, narrow-lane ambiguity resolution can be accelerated under the tight constraints derived from the ionosphere-corrected unambiguous wide-lane measurements. In the test at 90 static stations suffering from simulated total loss of tracking locks, 93.3 and 95.0% of re-convergences to wide-lane and narrow-lane ambiguity resolutions can be achieved within five epochs of 1-Hz measurements, respectively, even though the time latency for the predicted ionospheric delays is up to 180 s. In the test at a mobile van moving in a GPS-adverse environment where satellite number significantly decreases and cycle slips frequently occur, only when the predicted ionospheric delays are applied can the rate of ambiguity-fixed epochs be dramatically improved from 7.7 to 93.6% of all epochs. Therefore, this method can potentially relieve the unrealistic requirement of a continuous open sky-view by most PPP applications and improve the practicability of real-time PPP. Numéro de notice : A2010-558 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-010-0404-4 date de publication en ligne : 14/08/2010 En ligne : https://doi.org/10.1007/s00190-010-0404-4 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=30750 [article]

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Rapid static positioning using GPS and GLONASS / Gerhard Beutler in Bulletin of geodesy and geomatics BGG, vol 69 n° 2 - 3 (December 2010)

Public [article]  inBulletin of geodesy and geomatics BGG > vol 69 n° 2 - 3 (December 2010) . - pp 179 - 194 Titre : Rapid static positioning using GPS and GLONASS Type de document : Article/Communication Auteurs : Gerhard Beutler, Auteur ; Michael Meindl, Auteur Année de publication : 2010 Article en page(s) : pp 179 - 194 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie spatiale [Termes descripteurs IGN] ambiguïté entière [Termes descripteurs IGN] Bernese [Termes descripteurs IGN] compensation Lambda [Termes descripteurs IGN] données GLONASS [Termes descripteurs IGN] données GNSS [Termes descripteurs IGN] positionnement statique rapide [Termes descripteurs IGN] résolution d'ambiguïté [Termes descripteurs IGN] traitement de données GNSS Résumé : (Auteur) For rapid static positioning, the combined analysis of all observed GNSS becomes more and more important in view of the steadily increasing number of active satellites (early in 2009 exceeding 50 GPS+GLONASS satellites). Successful ambiguity fixing for all involved GNSS is the key for this application. First results of an implementation of a «GNSS-capable» LAMBDA ambiguity resolution scheme into a project version of the Bernese Software are presented. Numéro de notice : A2010-596 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=31340 [article]

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Fast GNSS ambiguity resolution as an ill-posed problem / Lard Erik Sjöberg in Journal of geodesy, vol 84 n° 11 (November 2010)  

Public [article]  inJournal of geodesy > vol 84 n° 11 (November 2010) . - pp 699 - 702 Titre : Fast GNSS ambiguity resolution as an ill-posed problem Type de document : Article/Communication Auteurs : Lard Erik Sjöberg, Auteur Année de publication : 2010 Article en page(s) : pp 699 - 702 Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie spatiale [Termes descripteurs IGN] ambiguïté entière [Termes descripteurs IGN] matrice de covariance [Termes descripteurs IGN] mesurage de phase [Termes descripteurs IGN] phase GNSS [Termes descripteurs IGN] positionnement par GNSS [Termes descripteurs IGN] problème inverse [Termes descripteurs IGN] résolution d'ambiguïté Résumé : (Auteur) A linear observational equation system for real-time GNSS carrier phase ambiguity resolution (AR) is often severely ill-posed in the case of poor satellite geometry. An ill-posed system may result in unreliable or unsuccessful AR if no care is taken to mitigate this situation. In this paper, the GNSS AR model as an ill-posed problem is solved by regularizing its baseline and ambiguity parameters, respectively, with the threefold contributions: (i) The regularization parameter is reliably determined in context of minimizing mean square error of regularized solution where the covariance matrix of initial values of unknowns is used as an approximate smoothness term instead of the quadratic matrix of the true values of unknowns; (ii) The different models for computing initial values of unknowns are systematically discussed in order to address the potential schemes in real world applications; (iii) The superior performance of the regularized AR are demonstrated through the numerically random simulations as well as the real GPS experiments. The results show that the proposed regularization strategies can effectively mitigate the model’s ill-condition and improve the success AR probability of the observational system with a severely ill-posed problem. Numéro de notice : A2010-478 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-010-0403-5 date de publication en ligne : 22/08/2010 En ligne : https://doi.org/10.1007/s00190-010-0403-5 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=30671 [article]

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Integer ambiguity resolution in precise point positionning : method comparison / J. Geng in Journal of geodesy, vol 84 n° 9 (September 2010)  

Public [article]  inJournal of geodesy > vol 84 n° 9 (September 2010) . - pp 569 - 581 Titre : Integer ambiguity resolution in precise point positionning : method comparison Type de document : Article/Communication Auteurs : J. Geng, Auteur ; X. Meng, Auteur ; A. Dodson, Auteur ; Felix Norman Teferle, Auteur Année de publication : 2010 Article en page(s) : pp 569 - 581 Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie spatiale [Termes descripteurs IGN] ambiguïté entière [Termes descripteurs IGN] analyse comparative [Termes descripteurs IGN] positionnement par GNSS [Termes descripteurs IGN] positionnement ponctuel précis [Termes descripteurs IGN] précision millimétrique [Termes descripteurs IGN] résolution d'ambiguïté Résumé : (Auteur) Integer ambiguity resolution at a single receiver can be implemented by applying improved satellite products where the fractional-cycle biases (FCBs) have been separated from the integer ambiguities in a network solution. One method to achieve these products is to estimate the FCBs by averaging the fractional parts of the float ambiguity estimates, and the other is to estimate the integer-recovery clocks by fixing the undifferenced ambiguities to integers in advance. In this paper, we theoretically prove the equivalence of the ambiguity-fixed position estimates derived from these two methods by assuming that the FCBs are hardware-dependent and only they are assimilated into the clocks and ambiguities. To verify this equivalence, we implement both methods in the Position and Navigation Data Analyst software to process 1 year of GPS data from a global network of about 350 stations. The mean biases between all daily position estimates derived from these two methods are only 0.2, 0.1 and 0.0 mm, whereas the standard deviations of all position differences are only 1.3, 0.8 and 2.0 mm for the East, North and Up components, respectively. Moreover, the differences of the position repeatabilities are below 0.2 mm on average for all three components. The RMS of the position estimates minus those from the International GNSS Service weekly solutions for the former method differs by below 0.1 mm on average for each component from that for the latter method. Therefore, considering the recognized millimeter-level precision of current GPS-derived daily positions, these statistics empirically demonstrate the theoretical equivalence of the ambiguity-fixed position estimates derived from these two methods. In practice, we note that the former method is compatible with current official clock-generation methods, whereas the latter method is not, but can potentially lead to slightly better positioning quality. Numéro de notice : A2010-416 Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-010-0399-x date de publication en ligne : 06/08/2010 En ligne : https://doi.org/10.1007/s00190-010-0399-x Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=30609 [article]

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Integer least-squares theory for the GNSS compass / Peter J.G. Teunissen in Journal of geodesy, vol 84 n° 7 (July 2010)  

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GNSS three carrier ambiguity resolution using ionosphere-reduced virtual signals / Y. Feng in Journal of geodesy, vol 82 n° 12 (December 2008)

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Ambiguity resolution in the air: mapping without stable GPS signals / J. Hutton in GIM international, vol 22 n° 11 (November 2008)

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A systematic investigation of optimal carrier-phase combinations for modernized triple-frequency GPS / Marc Cocard in Journal of geodesy, vol 82 n° 9 (September 2008)

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ADOP in closed form for a hierarchy of multi-frequency single-baseline GNSS models / Dennis Odijk in Journal of geodesy, vol 82 n° 8 (August 2008)

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Resolution of GPS carrier-phase ambiguities in Precise Point Positioning (PPP) with daily observations / M. Ge in Journal of geodesy, vol 82 n° 7 (July 2008)

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Influence of ambiguity precision on the success rate of GNSS integer ambiguity bootstrapping / Peter J.G. Teunissen in Journal of geodesy, vol 81 n° 5 (May 2007)

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Network RTK: getting ready for GNSS modernization / H. Landau in GPS world, vol 18 n° 4 (April 2007)

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Efficiency of carrier-phase integer ambiguity resolution for precise GPS positioning in noisy environments / L. Zhu in Journal of geodesy, vol 81 n° 2 (February 2007)

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Développement d'un logiciel de traitement de données GPS dans le cadre des réseaux GNSS temps réel / Omid Kamali (2006)

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