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The Bayesian detection of discontinuities in a polynomial regression and its application to the cycle-slip problem / M.C. DE Lacy in Journal of geodesy, vol 82 n° 9 (September 2008)  

Public [article]  inJournal of geodesy > vol 82 n° 9 (September 2008) . - pp 527 - 542 Titre : The Bayesian detection of discontinuities in a polynomial regression and its application to the cycle-slip problem Type de document : Article/Communication Auteurs : M.C. DE Lacy, Auteur ; M. Reguzzoni, Auteur ; Fernando Sanso, Auteur ; Giovanna Venuti, Auteur Année de publication : 2008 Article en page(s) : pp 527 - 542 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie spatiale [Termes IGN] Bernese [Termes IGN] correction du signal [Termes IGN] phase GNSS [Termes IGN] Ploynôme [Termes IGN] quantité discrète [Termes IGN] régression [Termes IGN] réseau bayesien [Termes IGN] traitement de données GNSS Résumé : (Auteur) This paper deals with the problem of detecting and correcting cycle-slips in Global Navigation Satellite System (GNSS) phase data by exploiting the Bayesian theory. The method is here applied to undifferenced observations, because repairing cycle-slips already at this stage could be a useful pre-processing tool, especially for a network of permanent GNSS stations. If a dual frequency receiver is available, the cycle-slips can be easily detected by combining two phase observations or phase and range observations from a single satellite to a single receiver. These combinations, expressed in a distance unit form, are completely free from the geometry and depend only on the ionospheric effect, on the electronic biases and on the initial integer ambiguities; since these terms are expected to be smooth in time, at least in a short period, a cycle-slip in one or both the two carriers can be modelled as a discontinuity in a polynomial regression. The proposed method consists in applying the Bayesian theory to compute the marginal posterior distribution of the discontinuity epoch and to detect it as a maximum a posteriori (MAP) in a very accurate way. Concerning the cycle-slip correction, a couple of simultaneous integer slips in the two carriers is chosen by maximazing the conditional posterior distribution of the discontinuity amplitude given the detected epoch. Numerical experiments on simulated and real data show that the discontinuities with an amplitude 2 or 3 times larger than the noise standard deviation are successfully identified. This means that the Bayesian approach is able to detect and correct cycle-slips using undifferenced GNSS observations even if the slip occurs by one cycle. A comparison with the scientific software BERNESE 5.0 confirms the good performance of the proposed method, especially when data sampled at high frequency (e.g. every 1 s or every 5 s) are available. Copyright Springer Numéro de notice : A2008-349 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-007-0203-8 En ligne : https://doi.org/10.1007/s00190-007-0203-8 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=29342 [article]

Exemplaires(2)

Code-barres	Cote	Support	Localisation	Section	Disponibilité
266-08081	RAB	Revue	Centre de documentation	En réserve L003	Disponible
266-08082	RAB	Revue	Centre de documentation	En réserve L003	Disponible

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)  

Public [article]  inJournal of geodesy > vol 82 n° 9 (September 2008) . - pp 555 - 564 Titre : A systematic investigation of optimal carrier-phase combinations for modernized triple-frequency GPS Type de document : Article/Communication Auteurs : Marc Cocard, Auteur ; S. Bourgon, Auteur ; Omid Kamali, Auteur ; P. Collins, Auteur Année de publication : 2008 Article en page(s) : pp 555 - 564 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie spatiale [Termes IGN] ambiguïté entière [Termes IGN] correction ionosphérique [Termes IGN] matrice de covariance [Termes IGN] méthode des moindres carrés [Termes IGN] phase GPS [Termes IGN] précision centimétrique [Termes IGN] propagation ionosphérique [Termes IGN] résolution d'ambiguïté [Termes IGN] signal GPS [Termes IGN] traitement de données GNSS Résumé : (Auteur) The upcoming modernization of the GPS signals will allow for measurements on an additional third frequency L5 located at 1176.45 MHz. To take advantage of carrier-phase measurements on this new signal, the strategies for integer ambiguity resolution, required for centimeter-level accuracy, may need to be revised. The Least-squares Ambiguity Decorrelation Adjustment method remains perhaps the most powerful tool for finding the best combinations based on a complete decorrelation of the variance–covariance matrix related to the ambiguities. However, the computational load of that method plus the opportunity to comprehensively study the interaction of multiple frequencies suggest a reconsideration of approaches using predefined combinations between frequencies is not out of place. In this paper a systematic investigation is made of all possible triple-frequency geometry-free carrier-phase combinations which retain the integer nature of the ambiguities. The concept of the lane-number is presented to unambiguously describe the wavelength of a particular combination. The propagation of the observation noise and of the ionospheric bias on these combinations is presented. These noise and ionospheric amplification factors are analysed with respect to the resulting wavelength, in an effort to highlight optimal combinations characterized by a long wavelength, low noise and limited ionospheric impact. Copyright Springer Numéro de notice : A2008-350 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-007-0201-x En ligne : https://doi.org/10.1007/s00190-007-0201-x Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=29343 [article]

Exemplaires(2)

Code-barres	Cote	Support	Localisation	Section	Disponibilité
266-08081	RAB	Revue	Centre de documentation	En réserve L003	Disponible
266-08082	RAB	Revue	Centre de documentation	En réserve L003	Disponible

The gravitational effect of ocean tide loading at high latitude coastal stations in Norway / D.I. Lysaker in Journal of geodesy, vol 82 n° 9 (September 2008)  

Public [article]  inJournal of geodesy > vol 82 n° 9 (September 2008) . - pp 569 - 583 Titre : The gravitational effect of ocean tide loading at high latitude coastal stations in Norway Type de document : Article/Communication Auteurs : D.I. Lysaker, Auteur ; K. Breili, Auteur ; Bjørn Ragnvald Pettersen, Auteur Année de publication : 2008 Article en page(s) : pp 569 - 583 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie physique [Termes IGN] analyse comparative [Termes IGN] Arctique [Termes IGN] champ de pesanteur local [Termes IGN] champ de pesanteur terrestre [Termes IGN] correction du signal [Termes IGN] déformation de la croute terrestre [Termes IGN] levé gravimétrique [Termes IGN] littoral [Termes IGN] Norvège [Termes IGN] série temporelle [Termes IGN] surcharge océanique Résumé : (Auteur) Gravity measurements close to the ocean are strongly affected by ocean tide loading (OTL). The gravitational OTL effect consists of three parts, i.e. a change in gravity caused by direct attraction from the variable water-masses, by displacement of the observing point due to the load, and by redistribution of masses due to crustal deformation. We compare the OTL gravitational effect of several global models to observed time-series of gravity to identify the best model for four arctic observation sites. We also investigate if the global models are sufficient for correcting gravity observations. The NAO99b model fits the observations best at three stations. At two stations (Tromsø and Bodø) the global models explain the variability in the observations well. At the other two (Honningsvåg and Andøya), a significant periodic signal remains after the OTL correction has been applied. We separate two of the gravitational effects, the direct attraction and the change in gravity due to displacement, to study the local effects. Simple geometric models of the water load and independent measurements from local tide-gauges are used to calculate these effects. This leads to improved correspondence with the OTL signal, hence demonstrating the importance of careful modelling of local effects for correction of gravity observations in coastal stations. Copyright Springer Numéro de notice : A2008-351 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-007-0207-4 En ligne : https://doi.org/10.1007/s00190-007-0207-4 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=29344 [article]

Exemplaires(2)

Code-barres	Cote	Support	Localisation	Section	Disponibilité
266-08081	RAB	Revue	Centre de documentation	En réserve L003	Disponible
266-08082	RAB	Revue	Centre de documentation	En réserve L003	Disponible