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GNSS interferometric radio occultation / Manuel Martín-Neira in IEEE Transactions on geoscience and remote sensing, vol 54 n° 9 (September 2016)  

Public [article]  inIEEE Transactions on geoscience and remote sensing > vol 54 n° 9 (September 2016) . - pp 5285 - 5300 Titre : GNSS interferometric radio occultation Type de document : Article/Communication Auteurs : Manuel Martín-Neira, Auteur Année de publication : 2016 Article en page(s) : pp 5285 - 5300 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Traitement du signal [Termes IGN] altimétrie [Termes IGN] autocorrélation [Termes IGN] autocorrélation spatiale [Termes IGN] diffusomètre [Termes IGN] estimation des paramètres [Termes IGN] interférométrie [Termes IGN] radiooccultation [Termes IGN] rapport signal sur bruit [Termes IGN] réflectométrie par GNSS [Termes IGN] signal GNSS Résumé : (Auteur) GNSS Reflectometry, Scatterometry and Radio Occultation aboard ISS is the mission concept under study within the European Space Agency. Its core payload consists of an interferometric GNSS-Reflectometry ocean altimeter/scatterometer which does not need to generate any clean replicas of the GNSS codes for its operation. This paper describes a new interferometric technique by which such payload could also perform radio occultation as an add-on, without requiring any additional hardware resources, like the generation of clean code replicas or a storage of them. Two possibilities are studied. The first one consists of performing the complex autocorrelation function of the received signal transmitted by a rising or setting GNSS satellite. The autocorrelation function is evaluated around time epochs that are multiples of the period of suitable codes found in the modulation of the navigation signals. Satellite discrimination has to be performed spatially, through the antenna pattern. The second possibility consists in acquiring the reference signal separately from the occultation event which, in turn, has two options depending upon the geometry at which the reference is recorded: zenithal and top of the atmosphere. The signal-to-noise ratio, the satellite discrimination, and the impact of clock errors are assessed. Numéro de notice : A2016-898 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1109/TGRS.2016.2559944 En ligne : https://doi.org/10.1109/TGRS.2016.2559944 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=83091 [article]

A novel methodology for identifying environmental exposures using GPS data / Andreea Cetateanu in International journal of geographical information science IJGIS, vol 30 n° 9-10 (September - October 2016)  

Public [article]  inInternational journal of geographical information science IJGIS > vol 30 n° 9-10 (September - October 2016) . - pp 1944 - 1960 Titre : A novel methodology for identifying environmental exposures using GPS data Type de document : Article/Communication Auteurs : Andreea Cetateanu, Auteur ; Bogdan-Alexandru Luca, Auteur ; Andrei Alin Popescu, Auteur ; et al., Auteur Année de publication : 2016 Article en page(s) : pp 1944 - 1960 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Analyse spatiale [Termes IGN] données GPS [Termes IGN] durée de trajet [Termes IGN] santé [Termes IGN] véhicule automobile [Termes IGN] voisinage (relation topologique) Résumé : (Auteur) Aim: While studies using global positioning systems (GPS) have the potential to refine measures of exposure to the neighbourhood environment in health research, one limitation is that they do not typically identify time spent undertaking journeys in motorised vehicles when contact with the environment is reduced. This paper presents and tests a novel methodology to explore the impact of this concern. Methods: Using a case study of exposure assessment to food environments, an unsupervised computational algorithm is employed in order to infer two travel modes: motorised and non-motorised, on the basis of which trips were extracted. Additional criteria are imposed in order to improve robustness of the algorithm. Results: After removing noise in the GPS data and motorised vehicle journeys, 82.43% of the initial GPS points remained. In addition, after comparing a sub-sample of trips classified visually of motorised, non-motorised and mixed mode trips with the algorithm classifications, it was found that there was an agreement of 88%. The measures of exposure to the food environment calculated before and after algorithm classification were strongly correlated. Conclusion: Identifying non-motorised exposures to the food environment makes little difference to exposure estimates in urban children but might be important for adults or rural populations who spend more time in motorised vehicles. Numéro de notice : A2016-572 Affiliation des auteurs : non IGN Thématique : GEOMATIQUE Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1080/13658816.2016.1145682 En ligne : http://dx.doi.org/10.1080/13658816.2016.1145682 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=81728 [article]

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Real-time cycle-slip detection and repair for BeiDou triple-frequency undifferenced observations / Y.-F. Yao in Survey review, vol 48 n° 350 (September 2016)  

Public [article]  inSurvey review > vol 48 n° 350 (September 2016) . - pp 367 - 375 Titre : Real-time cycle-slip detection and repair for BeiDou triple-frequency undifferenced observations Type de document : Article/Communication Auteurs : Y.-F. Yao, Auteur ; J.-X. Gao, Auteur ; J. Wang, Auteur ; et al., Auteur Année de publication : 2016 Article en page(s) : pp 367 - 375 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie spatiale [Termes IGN] détection d'anomalie [Termes IGN] glissement de cycle [Termes IGN] phase [Termes IGN] positionnement par BeiDou [Termes IGN] récepteur trifréquence [Termes IGN] signal BeiDou [Termes IGN] temps réel Résumé : (auteur) A new method of real-time cycle-slip detection and repair for BeiDou navigation satellite system (BDS) triple-frequency undifferenced observations is proposed. The method, which is based on code–phase and geometry-free phase combinations, composes linearly independent combination observations to uniquely determine the cycle-slip of original frequency phase observations in two independent steps. First, two extra-wide lane (EWL) code–phase combinations are utilised to determine the EWL combination cycle-slips. The sum of the carrier phase combination coefficients is zero. Second, the geometry-free phase combination with a non-zero sum of combination coefficients composes linearly independent combination observations with two code–phase combinations. Ionospheric delay variance systematic deviation is corrected with several previous carrier-phase observations without cycle-slip, which seriously affect the accuracy of the geometry-free phase combination observations. The BDS triple-frequency carrier-phase and code observations of different satellite types at 30 s sampling interval, which involve increased active ionospheric conditions in 1 day, are utilised to test the method. Results show that the proposed method can efficiently detect and accurately repair any cycle-slip combinations in real-time for different satellite types under active ionospheric conditions. No erroneous and leakage judgments are observed in the test. Numéro de notice : A2016-642 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article DOI : 10.1080/00396265.2015.1133518 En ligne : https://doi.org/10.1080/00396265.2015.1133518 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=81847 [article]

Taking correlations in GPS least squares adjustments into account with a diagonal covariance matrix / Gaël Kermarrec in Journal of geodesy, vol 90 n° 9 (September 2016)  

Public [article]  inJournal of geodesy > vol 90 n° 9 (September 2016) . - pp 793 – 805 Titre : Taking correlations in GPS least squares adjustments into account with a diagonal covariance matrix Type de document : Article/Communication Auteurs : Gaël Kermarrec, Auteur ; Steffen Schön, Auteur Année de publication : 2016 Article en page(s) : pp 793 – 805 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Termes IGN] compensation par moindres carrés [Termes IGN] corrélation [Termes IGN] données GPS [Termes IGN] estimateur [Termes IGN] matrice de covariance [Termes IGN] matrice diagonale [Termes IGN] pondération [Termes IGN] positionnement différentiel [Termes IGN] positionnement par GPS [Termes IGN] régression [Termes IGN] série temporelle [Vedettes matières IGN] Traitement de données GNSS Résumé : (auteur) Based on the results of Luati and Proietti (Ann Inst Stat Math 63:673–686, 2011) on an equivalence for a certain class of polynomial regressions between the diagonally weighted least squares (DWLS) and the generalized least squares (GLS) estimator, an alternative way to take correlations into account thanks to a diagonal covariance matrix is presented. The equivalent covariance matrix is much easier to compute than a diagonalization of the covariance matrix via eigenvalue decomposition which also implies a change of the least squares equations. This condensed matrix, for use in the least squares adjustment, can be seen as a diagonal or reduced version of the original matrix, its elements being simply the sums of the rows elements of the weighting matrix. The least squares results obtained with the equivalent diagonal matrices and those given by the fully populated covariance matrix are mathematically strictly equivalent for the mean estimator in terms of estimate and its a priori cofactor matrix. It is shown that this equivalence can be empirically extended to further classes of design matrices such as those used in GPS positioning (single point positioning, precise point positioning or relative positioning with double differences). Applying this new model to simulated time series of correlated observations, a significant reduction of the coordinate differences compared with the solutions computed with the commonly used diagonal elevation-dependent model was reached for the GPS relative positioning with double differences, single point positioning as well as precise point positioning cases. The estimate differences between the equivalent and classical model with fully populated covariance matrix were below the mm for all simulated GPS cases and below the sub-mm for the relative positioning with double differences. These results were confirmed by analyzing real data. Consequently, the equivalent diagonal covariance matrices, compared with the often used elevation-dependent diagonal covariance matrix is appropriate to take correlations in GPS least squares adjustment into account, yielding more accurate cofactor matrices of the unknown. Numéro de notice : A2016-654 Affiliation des auteurs : non IGN Thématique : MATHEMATIQUE/POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-016-0911-z En ligne : http://dx.doi.org/10.1007/s00190-016-0911-z Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=81856 [article]

Use of a GPS-derived troposphere model to improve InSAR deformation estimates in the San Gabriel Valley, California / Nicolas Houlié in IEEE Transactions on geoscience and remote sensing, vol 54 n° 9 (September 2016)  

Public [article]  inIEEE Transactions on geoscience and remote sensing > vol 54 n° 9 (September 2016) . - pp 5365 - 5374 Titre : Use of a GPS-derived troposphere model to improve InSAR deformation estimates in the San Gabriel Valley, California Type de document : Article/Communication Auteurs : Nicolas Houlié, Auteur ; Gareth J. Funning, Auteur ; Roland Bürgmann, Auteur Année de publication : 2016 Article en page(s) : pp 5365 - 5374 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Traitement d'image radar et applications [Termes IGN] Californie (Etats-Unis) [Termes IGN] déformation de la croute terrestre [Termes IGN] image Envisat [Termes IGN] image radar [Termes IGN] interféromètrie par radar à antenne synthétique [Termes IGN] propagation troposphérique [Termes IGN] signal GPS Résumé : (Auteur) We evaluate the potential of troposphere models derived from ground meteorological data (pressure, temperature, and relative humidity) and Global Positioning System (GPS) data to improve InSAR measurements and models derived from them. We test this approach on an ERS-2/Envisat data set collected during a transient surface deformation episode that occurred from January to July 2005 in the San Gabriel Valley, southern California, USA. We find that the interferometric phase change observed over the corresponding period cannot be solely attributed to hydrological uplift associated with rising groundwater levels but also includes a significant contribution from differential tropospheric delay due to differing quantities of water vapor in the troposphere on the two SAR observation dates. We show that, if the tropospheric phase contribution is mistakenly interpreted as the range change associated with changes in groundwater storage, both the surface displacement and the groundwater storage coefficient may be overestimated by up to 30%. This method could be applied in real time where meteorological measurements are available near one or more GPS permanent site(s). Numéro de notice : A2016-900 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1109/TGRS.2016.2561971 En ligne : https://doi.org/10.1109/TGRS.2016.2561971 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=83093 [article]

Automatic extraction of road networks from GPS traces / Jia Qiu in Photogrammetric Engineering & Remote Sensing, PERS, vol 82 n° 8 (August 2016)  

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Estimation of satellite antenna phase center offsets for Galileo / Peter Steigenberger in Journal of geodesy, vol 90 n° 8 (August 2016)  

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A geometry-free and ionosphere-free multipath mitigation method for BDS three-frequency ambiguity resolution / Dezhong Chen in Journal of geodesy, vol 90 n° 8 (August 2016)  

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Interference mitigation in the E5A Galileo band using an open-source simulator / Diego Alonso in Inside GNSS, vol 11 n° 4 (July - August 2016)  

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Stochastic modeling of triple-frequency BeiDou signals: estimation, assessment and impact analysis / Bofeng Li in Journal of geodesy, vol 90 n° 7 (July 2016)  

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The IGS contribution to ITRF2014 / Paul Rebischung in Journal of geodesy, vol 90 n° 7 (July 2016)  

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Assessment of continental hydrosphere loading using GNSS measurements / Michał Zygmunt in Reports on geodesy and geoinformatics, vol 101 (June 2016)  

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Listening for RF noise : An analysis of pre-despreading GNSS interference detection techniques / Ali Jafarnia-Jahromi in Inside GNSS, vol 11 n° 3 (May - June 2016)  

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GNSS threat quantification in the United Kingdom in 2015 / Chaz Dixon in Navigation aérienne, maritime, spatiale, terrestre, vol 63 n° 250 (mai - août 2016)

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GLONASS fractional-cycle bias estimation across inhomogeneous receivers for PPP ambiguity resolution / Jianghui Geng in Journal of geodesy, vol 90 n° 4 (April 2016)  

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Performance analysis of triple-frequency ambiguity resolution with BeiDou observations / Xiaohong Zhang in GPS solutions, vol 20 n° 2 (April 2016)  

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A study on the dependency of GNSS pseudorange biases on correlator spacing / André Hauschild in GPS solutions, vol 20 n° 2 (April 2016)  

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Accuracy of ionospheric models used in GNSS and SBAS: methodology and analysis / Adria Rovira-Garcia in Journal of geodesy, vol 90 n° 3 (March 2016)  

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Combined Architecture : Enhancing Multi-Dimensional Signal Quality in GNSS Receivers / Nunzia Giorgia Ferrara in Inside GNSS, vol 11 n° 2 (March - April 2016) 

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Core wall control survey / Joël Van Cranenbroeck in GIM international, vol 30 n° 3 (March 2016)

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Precise orbit determination based on raw GPS measurements / Norbert Zehentner in Journal of geodesy, vol 90 n° 3 (March 2016)  

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Image based geo-localization in the Alps / Olivier Saurer in International journal of computer vision, vol 116 n° 3 (February 2016)  

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Advanced modeling and algorithms for high-precision GNSS analysis / Kan Wang (2016)  

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Caractérisation des signaux et des bruits des séries temporelles du géocentre et des paramètres de rotation de la Terre (EOP) / Bachir Gourine in Bulletin des sciences géographiques, n° 30 (2015 - 2016)

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Combination of GNSS and SLR measurements : contribution to the realization of the terrestrial reference frame / Sara Bruni (2016)  

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