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GPS snow depth meter with geometry-free linear combinations of carrier phases / M. Ozeki in Journal of geodesy, vol 86 n° 3 (March 2012)  

Public [article]  inJournal of geodesy > vol 86 n° 3 (March 2012) . - pp 209 - 217 Titre : GPS snow depth meter with geometry-free linear combinations of carrier phases Type de document : Article/Communication Auteurs : M. Ozeki, Auteur ; K. Heki, Auteur Année de publication : 2012 Article en page(s) : pp 209 - 217 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Applications de géodésie spatiale [Termes IGN] antenne GPS [Termes IGN] combinaison linéaire [Termes IGN] Hokkaido (Japon) [Termes IGN] neige [Termes IGN] phase GPS [Termes IGN] rapport signal sur bruit [Termes IGN] traitement de données GNSS [Termes IGN] trajet multiple Résumé : (Auteur) Multipath in global positioning system (GPS) is the interference of the microwave signals directly from satellites and those reflected before reaching the antenna, typically by the ground. Because reflected signals cause positioning errors, GPS antennas are designed to reduce such interference. Recent studies show that multipath could be utilized to infer the properties of the ground around the antenna. Here, we report one such application, i.e. a fixed GPS station used as a snow depth meter. Because the satellite moves in the sky, the excess path length of reflected waves changes at rates dependent on the antenna height. This causes quasi-periodic variations of the amplitude and phase of the received signals. Accumulation of snow reduces effective antenna heights, and we can see it by analyzing multipath signatures. Signal-to-noise ratios (SNR) are often used to analyze multipath, but they are not always available in raw GPS data files. Here, we demonstrate that the geometry-free linear combination (L4), normally used to study the ionosphere, can also be used to analyze multipath signatures. We obtained snow depth time series at a GPS station in Hokkaido, Japan, from January to April in 2009 using L4 and SNR. Then, we compared their precisions. We also discuss mechanisms responsible for the possible underestimation of the snow depth by GPS. Finally, we investigate the possibility of inferring physical conditions of the snow surface using amplitudes of multipath signatures. Numéro de notice : A2012-150 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-011-0511-x Date de publication en ligne : 14/09/2011 En ligne : https://doi.org/10.1007/s00190-011-0511-x Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=31597 [article]

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