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Statistical comparison and combination of GPS, GLONASS, and multi-GNSS multipath reflectometry applied to snow depth retrieval / Sajad Tabibi in IEEE Transactions on geoscience and remote sensing, vol 55 n° 7 (July 2017)  

Public [article]  inIEEE Transactions on geoscience and remote sensing > vol 55 n° 7 (July 2017) . - pp 3773 - 3785 Titre : Statistical comparison and combination of GPS, GLONASS, and multi-GNSS multipath reflectometry applied to snow depth retrieval Type de document : Article/Communication Auteurs : Sajad Tabibi, Auteur ; Felipe Geremia-Nievinski, Auteur ; Tonie M. van Dam, Auteur Année de publication : 2017 Article en page(s) : pp 3773 - 3785 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Applications de géodésie spatiale [Termes descripteurs IGN] épaisseur [Termes descripteurs IGN] neige [Termes descripteurs IGN] positionnement par GLONASS [Termes descripteurs IGN] positionnement par GNSS [Termes descripteurs IGN] positionnement par GPS [Termes descripteurs IGN] réflectométrie par GNSS [Termes descripteurs IGN] série temporelle Résumé : (Auteur) Global navigation satellite system (GNSS) multipath reflectometry (MR) has emerged as a new technique that uses signals of opportunity broadcast by GNSS satellites and tracked by ground-based receivers to retrieve environmental variables such as snow depth. The technique is based on the simultaneous reception of direct or line-of-sight (LOS) transmissions and corresponding coherent surface reflections (non-LOS). Until recently, snow depth retrieval algorithms only used legacy and modernized GPS signals. Using multiple GNSS constellations for reflectometry would improve GNSS-MR applications by providing more observations from more satellites and independent signals (carrier frequencies and code modulations). We assess GPS and GLONASS for combined multi-GNSS-MR using simulations as well as field measurements. Synthetic observations for different signals indicated a lack of detectable interfrequency and intercode biases in GNSS-MR snow depth retrievals. Received signals from a GNSS station continuously operating in France for a two-winter period are used for experimental snow depth retrieval. We perform an internal validation of various GNSS signals against the proven GPS-L2-C signal, which was validated externally against in situ snow depth in previous studies. GLONASS observations required a more complex handling to account for topography because of its particular ground track repeatability. Signal intercomparison show an average correlation of 0.922 between different GPS snow depths and GPS-L2-CL, while GLONASS snow depth retrievals have an average correlation that exceeds 0.981. In terms of precision and accuracy, legacy GPS signals are worse, while GLONASS signals and modernized GPS signals are of comparable quality. Finally, we show how an optimal multi-GNSS combined daily snow depth time series can be formed employing variance factors with a ~59%-90% precision improvement compared to individual signal snow depth retrievals, resulting in snow depth retrieval with uncertainty of 1.3 cm. The developed combination strategy can also be applied for the European Galileo and the Chines BeiDou navigation systems. Numéro de notice : A2017-487 Thématique : IMAGERIE Nature : Article nature-HAL : ArtAvecCL-RevueIntern En ligne : http://dx.doi.org/10.1109/TGRS.2017.2679899 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=86414 [article]

SlopeManagement via satellite navigation / Daniel Maurice in Geoinformatics, vol 18 n° 8 (December 2015)

Public [article]  inGeoinformatics > vol 18 n° 8 (December 2015) . - pp 16 - 17 Titre : SlopeManagement via satellite navigation Type de document : Article/Communication Auteurs : Daniel Maurice, Auteur Année de publication : 2015 Article en page(s) : pp 16 - 17 Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Applications de géodésie spatiale [Termes descripteurs IGN] Autriche [Termes descripteurs IGN] épaisseur [Termes descripteurs IGN] manteau neigeux [Termes descripteurs IGN] neige [Termes descripteurs IGN] pente Numéro de notice : A2015-805 Thématique : POSITIONNEMENT Nature : Article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=78833 [article]

Snow depth estimation based on multipath phase combination of GPS triple-frequency signals / Keguen Yu in IEEE Transactions on geoscience and remote sensing, vol 53 n° 9 (September 2015)

Public [article]  inIEEE Transactions on geoscience and remote sensing > vol 53 n° 9 (September 2015) . - pp 5100 - 5109 Titre : Snow depth estimation based on multipath phase combination of GPS triple-frequency signals Type de document : Article/Communication Auteurs : Keguen Yu, Auteur ; Wei Ban, Auteur ; Xiaohong Zhang, Auteur ; Xingwang Yu, Auteur Année de publication : 2015 Article en page(s) : pp 5100 - 5109 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Applications de géodésie spatiale [Termes descripteurs IGN] données GPS [Termes descripteurs IGN] épaisseur [Termes descripteurs IGN] manteau neigeux [Termes descripteurs IGN] mesurage de phase [Termes descripteurs IGN] mesure géométrique [Termes descripteurs IGN] onde porteuse [Termes descripteurs IGN] positionnement par GNSS [Termes descripteurs IGN] récepteur trifréquence [Termes descripteurs IGN] réflectométrie par GNSS Résumé : (Auteur) Snow is important to the ecological and climate systems; however, current snowfall and snow depth in situ observations are only available sparsely on the globe. By making use of the networks of Global Positioning System (GPS) stations established for geodetic applications, it is possible to monitor snow distribution on a global scale in an inexpensive way. In this paper, we propose a new snow depth estimation approach using a geodetic GPS station, multipath reflectometry and a linear combination of phase measurements of GPS triple-frequency (L1, L2, and L5) signals. This phase combination is geometry free and is not affected by ionospheric delays. Analytical linear models are first established to describe the relationship between antenna height and spectral peak frequency of combined phase time series, which are calculated based on theoretical formulas. When estimating snow depth in real time, the spectral peak frequency of the phase measurements is obtained, and then the model is used to determine snow depth. Two experimental data sets recorded in two different environments were used to test the proposed method. The results demonstrate that the proposed method shows an improvement with respect to existing methods on average. Numéro de notice : A2015-553 Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=77588 [article]

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Image-domain estimation of wall parameters for autofocusing of through-the-wall SAR imagery / Tian Jin in IEEE Transactions on geoscience and remote sensing, vol 51 n° 3 Tome 2 (March 2013)

Public [article]  inIEEE Transactions on geoscience and remote sensing > vol 51 n° 3 Tome 2 (March 2013) . - pp 1836 - 1843 Titre : Image-domain estimation of wall parameters for autofocusing of through-the-wall SAR imagery Type de document : Article/Communication Auteurs : Tian Jin, Auteur ; Bo Chen, Auteur ; Zhimin Zhou, Auteur Année de publication : 2013 Article en page(s) : pp 1836 - 1843 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Traitement d'image radar et applications [Termes descripteurs IGN] constante diélectrique [Termes descripteurs IGN] détection à travers-le-mur [Termes descripteurs IGN] écho radar [Termes descripteurs IGN] épaisseur [Termes descripteurs IGN] image radar moirée [Termes descripteurs IGN] milieu urbain Résumé : (Auteur) Estimation of the basic parameters, wall thickness and dielectric constant, is important in through-the-wall radar imaging. Ambiguities in wall characteristics will degrade the image focusing quality of synthetic-aperture radar. In order to obtain a quick and precise estimation of wall parameters, an equivalent propagation model of an electromagnetic wave in the air-wall-air medium is first developed in this paper. According to the developed propagation model, two filter-based approaches, denoted respectively as the echo-domain-filter-based method and the image-domain-filter-based method, are proposed to estimate wall thickness and dielectric constant by adjusting the two corresponding parameters of the echo-domain filter or the image-domain filter to obtain the best focusing quality of behind-the-wall targets. The processing schemes of the two methods show that the image-domain-filter-based method is more efficient because it does not involve imaging processing in each adjustment. Moreover, the image-domain-filter-based method is accelerated by reducing the dimension of searching space to better the computational efficiency further. Simulation results show that the proposed accelerating image-domain-filter-based method can provide quick and precise estimation of wall parameters. Numéro de notice : A2013-136 Thématique : IMAGERIE Nature : Article nature-HAL : ArtAvecCL-RevueIntern Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=32274 [article]

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