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Discovery of new code interference phenomenon in GPS observables / Connor D. Flynn in GPS solutions, vol 23 n° 3 (July 2019)  

Public [article]  inGPS solutions > vol 23 n° 3 (July 2019) . - 9 p. Titre : Discovery of new code interference phenomenon in GPS observables Type de document : Article/Communication Auteurs : Connor D. Flynn, Auteur ; Anthony M. McCaffrey, Auteur ; P.T. Jayachandran, Auteur ; Richard B. Langley, Auteur Année de publication : 2019 Article en page(s) : 9 p. Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Navigation et positionnement [Termes descripteurs IGN] analyse spectrale [Termes descripteurs IGN] données Doppler [Termes descripteurs IGN] données GPS [Termes descripteurs IGN] Global Positioning System [Termes descripteurs IGN] interférence [Termes descripteurs IGN] modulation du signal [Termes descripteurs IGN] perturbation ionosphérique [Termes descripteurs IGN] scintillation [Termes descripteurs IGN] signal GPS Résumé : (auteur) The Global Positioning System (GPS) provides satellite-based navigation signals, which are employed in many fields, including agriculture, transportation, aviation, and military/personal navigation. In an effort to minimize interference among GPS satellites and to enable GPS receivers to discern satellite identity, each satellite is assigned a specific pseudorandom noise (PRN) sequence that is used to modulate the phase of the corresponding signal. The codes that modulate the current GPS landscape are constructed in such a way that cross-correlation among codes is kept to a bounded minimum, which should significantly limit harmful signal interference. In this study, the efficacy of the current PRN-based modulation system is called into question as GPS signal amplitude and carrier phase data over the past decade show frequent interference between satellite signals. Numéro de notice : A2019-197 Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s10291-019-0858-7 date de publication en ligne : 29/04/2019 En ligne : https://doi.org/10.1007/s10291-019-0858-7 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=92652 [article]

Visual analytics of time-varying multivariate ionospheric scintillation data / Aurea Soriano-Vargas in Computers and graphics, vol 68 (November 2017)  

Public [article]  inComputers and graphics > vol 68 (November 2017) . - pp 96 - 107 Titre : Visual analytics of time-varying multivariate ionospheric scintillation data Type de document : Article/Communication Auteurs : Aurea Soriano-Vargas, Auteur ; Bruno C. Vani, Auteur ; Milton H. Shimabukuro, Auteur ; João F.G. Monico, Auteur Année de publication : 2017 Article en page(s) : pp 96 - 107 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Termes descripteurs IGN] analyse géovisuelle [Termes descripteurs IGN] analyse multivariée [Termes descripteurs IGN] données spatiotemporelles [Termes descripteurs IGN] ionosphère [Termes descripteurs IGN] scintillation [Termes descripteurs IGN] visualisation de données [Vedettes matières IGN] Géovisualisation Résumé : (résumé) We present a clustering-based interactive approach to multivariate data analysis, motivated by the specific needs of scintillation data. Ionospheric scintillation is a rapid variation in the amplitude and/or phase of radio signals traveling through the ionosphere. This spatial and time-varying phenomenon is of great interest since it affects the reception quality of satellite signals. Specialized receivers at strategic regions can track multiple variables related to this phenomenon, generating a database of observations of regional ionospheric scintillation. We introduce a visual analytics solution to support analysis of such data, keeping in mind the general applicability of our approach to similar multivariate data analysis situations. Taking into account typical user questions, we combine visualization and data mining algorithms that satisfy these goals: (i) derive a representation of the variables monitored that conveys their behavior in detail, at multiple user-defined aggregation levels; (ii) provide overviews of multiple variables regarding their behavioral similarity over selected time periods; (iii) support users when identifying representative variables for characterizing scintillation behavior. We illustrate the capabilities of our proposed framework by presenting case studies driven directly by questions formulated by collaborating domain experts. Numéro de notice : A2017-452 Thématique : GEOMATIQUE Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1016/j.cag.2017.08.013 En ligne : https://doi.org/10.1016/j.cag.2017.08.013 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=86363 [article]

Automatic GPS ionospheric amplitude and phase scintillation detectors using a machine learning algorithm / Yu Jiao in Inside GNSS, vol 12 n° 3 (May - June 2017)  

Public [article]  inInside GNSS > vol 12 n° 3 (May - June 2017) . - pp 48 - 54 Titre : Automatic GPS ionospheric amplitude and phase scintillation detectors using a machine learning algorithm Type de document : Article/Communication Auteurs : Yu Jiao, Auteur ; John J. Hall, Auteur ; Yu T. Morton, Auteur Année de publication : 2017 Article en page(s) : pp 48 - 54 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Traitement du signal [Termes descripteurs IGN] amplitude [Termes descripteurs IGN] apprentissage automatique [Termes descripteurs IGN] détecteur [Termes descripteurs IGN] propagation ionosphérique [Termes descripteurs IGN] scintillation Résumé : (auteur) Ionospheric scintillation can cause errors or outage in GNSS services. Timely detection of ionospheric scintillation will enable adaptive processing to mitigate its effects on navigation solutions. This article presents a machine learning algorithm to autonomously detect ionospheric amplitude and phase scintillation. Systematic validations of the algorithm show the accuracies of amplitude and phase scintillation detections to be at around 98% and 92%, respectively. Tests were also conducted using data from locations not involved in training process and the results demonstrate the generalization capabilities of the scintillation detectors. In addition, concurrent amplitude and phase scintillation detection using similar machine learning algorithms is further investigated with low-latitude scintillation data. Our findings suggest that at low latitudes, amplitude detector alone is sufficient to capture scintillation in general. At high latitudes, phase scintillation is known to be the dominating phenomena and phase scintillation detector is necessary to capture the scintillation events. Numéro de notice : A2017-259 Thématique : POSITIONNEMENT Nature : Article En ligne : http://www.insidegnss.com/node/5467 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=85276 [article]

Correcting distortion of polarimetric SAR data induced by ionospheric scintillation / Jun Su Kim in IEEE Transactions on geoscience and remote sensing, vol 53 n° 12 (December 2015)

Public [article]  inIEEE Transactions on geoscience and remote sensing > vol 53 n° 12 (December 2015) . - pp 6319 - 6335 Titre : Correcting distortion of polarimetric SAR data induced by ionospheric scintillation Type de document : Article/Communication Auteurs : Jun Su Kim, Auteur ; Konstantinos Panagiotis Papathanassiou, Auteur ; Rolf Scheiber, Auteur ; et al., Auteur Année de publication : 2015 Article en page(s) : pp 6319 - 6335 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Traitement d'image radar et applications [Termes descripteurs IGN] bande L [Termes descripteurs IGN] bande P [Termes descripteurs IGN] correction ionosphérique [Termes descripteurs IGN] données polarimétriques [Termes descripteurs IGN] image ALOS-PALSAR [Termes descripteurs IGN] image radar moirée [Termes descripteurs IGN] polarimétrie radar [Termes descripteurs IGN] scintillation Résumé : (auteur) A correction methodology for distortions induced by ionospheric scintillation on fully polarimetric synthetic aperture radar (SAR) data is proposed. The correction is based on deriving the phase distortion induced by the ionosphere from Faraday rotation estimates. The estimated phase distortion is then used for correction. In order to compensate the phase and time-Doppler history distortions, the correction has to be performed at the slant range of the ionospheric layer, i.e., on partially focused single-look complex data. Accordingly, the performance of the proposed correction methodology depends, among other factors, on knowledge of the altitude of the effective ionospheric layer (assuming the thin ionospheric layer model). Its estimation from the SAR data itself is therefore also addressed. The methodology was applied and validated on simulated P-band data for various ionospheric conditions and on real L-band data acquired by the Advanced Land Observation Satellite Phased Array L-band SAR (PALSAR). Numéro de notice : A2015-842 Thématique : IMAGERIE Nature : Article nature-HAL : ArtAvecCL-RevueIntern Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=79186 [article]

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Mitigating the impact of ionospheric cycle slips in GNSS observations / Simon Banville in Journal of geodesy, vol 87 n° 2 (February 2013)

Public [article]  inJournal of geodesy > vol 87 n° 2 (February 2013) . - pp 179 - 193 Titre : Mitigating the impact of ionospheric cycle slips in GNSS observations Type de document : Article/Communication Auteurs : Simon Banville, Auteur ; R. Langley, Auteur Année de publication : 2013 Article en page(s) : pp 179 - 193 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie spatiale [Termes descripteurs IGN] Canada [Termes descripteurs IGN] données GNSS [Termes descripteurs IGN] positionnement ponctuel précis [Termes descripteurs IGN] propagation ionosphérique [Termes descripteurs IGN] scintillation [Termes descripteurs IGN] traitement de données GNSS Résumé : (Auteur) Processing of data from global navigation satellite systems (GNSS), such as GPS, GLONASS and Galileo, can be considerably impeded by disturbances in the ionosphere. Cycle-slip detection and correction thus becomes a crucial component of robust software. Still, dealing with ionospheric cycle slips is not trivial due to scintillation effects in both the phase and the amplitude of the signals. In this contribution, a geometry-based approach with rigorous handling of the ionosphere is presented. A detailed analysis of the cycle-slip correction process is also tackled by examining its dependence on phase and code noise, non-dispersive effects and, of course, the ionosphere. The importance of stochastic modeling in validating the integer cycle-slip candidates is emphasized and illustrated through simulations. By examining the relationship between ionospheric bias and ionospheric constraint, it is shown that there is a limit in the magnitude of ionospheric delay variation that can be handled by the cycle-slip correction process. Those concepts are applied to GNSS data collected by stations in northern Canada, and show that enhanced cycle-slip detection can lead to decimeter-level improvements in the accuracy of kinematic PPP solutions with a 30-s sampling interval. Cycle-slip correction associated with ionospheric delay variations exceeding 50 cm is also demonstrated, although there are risks with such a procedure and these are pointed out. Numéro de notice : A2013-100 Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=32238 [article]

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Ionospheric scintillations: How irregularities in electron density perturb satellite navigation systems / Satellite-based augmentation system ionospheric working group in GPS world, vol 23 n° 4 (April 2012)

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Improving the GNSS positioning stochastic model in the presence of ionospheric scintillation / M. Aquino in Journal of geodesy, vol 83 n° 10 (October 2009)

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Estimating atmospheric transmission and surface reflectance from a glint-contaminated spectral image / W. Philpot in IEEE Transactions on geoscience and remote sensing, vol 45 n° 2 (February 2007)

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Determination of thermal stratification and turbulence of the atmospheric surface layer over various types of terrain by optical scintillometry / A. Weiss (2002)

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Lasermessungen nach Erdsatelliten auf zwei Wellenlängen unter Verwendung einer Streak-Kamera / S. Riepl (1998)

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