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Reflecting on GPS: sensing land and ice from low Earth orbit / S.T. Gleason in GPS world, vol 18 n° 10 (October 2008)

Public [article]  inGPS world > vol 18 n° 10 (October 2008) . - pp 44 - 49 Titre : Reflecting on GPS: sensing land and ice from low Earth orbit Type de document : Article/Communication Auteurs : S.T. Gleason, Auteur Année de publication : 2007 Article en page(s) : pp 44 - 49 Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Applications de géodésie spatiale [Termes IGN] bruit rose [Termes IGN] glace [Termes IGN] réflectance [Termes IGN] signal GPS [Termes IGN] surveillance de la végétation [Termes IGN] traitement du signal Résumé : (Editeur) An out-of-the-ordinary application of GPS uses signals reflected of the Earth's surface to sense land and ice, as well as ocean surface, from low Earth orbit. Analysis of these signals holds great promise for measuring ocean roughness, ice conditions, vegetation cover, and even soil moisture. Copyright Questex Media Group Inc Numéro de notice : A2007-478 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article DOI : sans Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=28841 [article]

Exemplaires(1)

Code-barres	Cote	Support	Localisation	Section	Disponibilité
067-07101	SL	Revue	Centre de documentation	Revues en salle	Disponible

On the long-term stability of microwave radiometers using noise diodes for calibration / S.T. Brown in IEEE Transactions on geoscience and remote sensing, vol 45 n° 7 Tome 1 (July 2007)  

Public [article]  inIEEE Transactions on geoscience and remote sensing > vol 45 n° 7 Tome 1 (July 2007) . - pp 1908 - 1920 Titre : On the long-term stability of microwave radiometers using noise diodes for calibration Type de document : Article/Communication Auteurs : S.T. Brown, Auteur ; Shailen Desai, Auteur ; W. Lu, Auteur ; A.B. Tanner, Auteur Année de publication : 2007 Article en page(s) : pp 1908 - 1920 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Acquisition d'image(s) et de donnée(s) [Termes IGN] Advanced Microwave Radiometer [Termes IGN] bruit (théorie du signal) [Termes IGN] capteur spatial [Termes IGN] diode [Termes IGN] étalonnage de capteur (imagerie) [Termes IGN] radiomètre à hyperfréquence [Termes IGN] température de luminance [Termes IGN] water vapour radiometer Résumé : (Auteur) Results are presented from the long-term monitoring and calibration of the National Aeronautics and Space Administration Jason Microwave Radiometer (JMR) on the Jason-1 ocean altimetry satellite and the ground-based Advanced Water Vapor Radiometers (AWVRs) developed for the Cassini Gravity Wave Experiment. Both radiometers retrieve the wet tropospheric path delay (PD) of the atmosphere and use internal noise diodes (NDs) for gain calibration. The JMR is the first radiometer to be flown in space that uses NDs for calibration. External calibration techniques are used to derive a time series of ND brightness for both instruments that is greater than four years. For the JMR, an optimal estimator is used to find the set of calibration coefficients that minimize the root-mean-square difference between the JMR brightness temperatures and the on-Earth hot and cold references. For the AWVR, continuous tip curves are used to derive the ND brightness. For the JMR and AWVR, both of which contain three redundant NDs per channel, it was observed that some NDs were very stable, whereas others experienced jumps and drifts in their effective brightness. Over the four-year time period, the ND stability ranged from 0.2% to 3% among the diodes for both instruments. The presented recalibration methodology demonstrates that long-term calibration stability can be achieved with frequent recalibration of the diodes using external calibration techniques. The JMR PD drift compared to ground truth over the four years since the launch was reduced from 3.9 to $-$0.01 mm/year with the recalibrated ND time series. The JMR brightness temperature calibration stability is estimated to be 0.25 K over ten days. Copyright IEEE Numéro de notice : A2007-170 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1109/TGRS.2006.888098 En ligne : https://doi.org/10.1109/TGRS.2006.888098 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=28533 [article]

Exemplaires(1)

Code-barres	Cote	Support	Localisation	Section	Disponibilité
065-07071A	RAB	Revue	Centre de documentation	En réserve L003	Disponible

Quality assessment of SRTM C- and X-band interferometric data: Implications for the retrieval of vegetation canopy height / W.S. Walker in Remote sensing of environment, vol 106 n° 4 (28/02/2007)  

Public [article]  inRemote sensing of environment > vol 106 n° 4 (28/02/2007) . - pp 428 - 448 Titre : Quality assessment of SRTM C- and X-band interferometric data: Implications for the retrieval of vegetation canopy height Type de document : Article/Communication Auteurs : W.S. Walker, Auteur ; J.M. Kellndorfer, Auteur ; L.E. Pierce, Auteur Année de publication : 2007 Article en page(s) : pp 428 - 448 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Traitement d'image radar et applications [Termes IGN] bande C [Termes IGN] bande X [Termes IGN] bruit (théorie du signal) [Termes IGN] canopée [Termes IGN] erreur de mesure [Termes IGN] erreur relative [Termes IGN] Etats-Unis [Termes IGN] filtrage du bruit [Termes IGN] hauteur des arbres [Termes IGN] image SRTM [Termes IGN] interféromètrie par radar à antenne synthétique [Termes IGN] MNS SRTM [Termes IGN] modèle numérique de surface [Termes IGN] qualité des données [Termes IGN] radargrammétrie Résumé : (Auteur) The Shuttle Radar Topography Mission distinguished itself as the first near-global spaceborne mission to demonstrate direct sensitivity to vertical vegetation structure. Whether this sensitivity is viewed as exploitable signal or unwanted bias, a great deal of interest exists in retrieving vegetation canopy height information from the SRTM data. This study presents a comprehensive application-specific assessment of SRTM data quality, focusing on the characterization and mitigation of two primary sources of relative vertical error: uncompensated Shuttle mast motion and random phase noise. The assessment spans four test sites located in the upper Midwestern United States and examines the dependence of data quality on both frequency, i.e., C-band vs. X-band, and the number of acquired datatakes. The results indicate that the quality of SRTM data may be higher than previously thought. Novel mitigation strategies include a knowledge-based approach to sample averaging, which has the potential to reduce phase noise error by 43 to 80%. The strategies presented here are being implemented as part of an ongoing effort to produce regional- to continental-scale estimates of vegetation canopy height within the conterminous U.S. Copyright Elsevier Numéro de notice : A2007-068 Affiliation des auteurs : non IGN Thématique : FORET/IMAGERIE Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1016/j.rse.2006.09.007 En ligne : https://doi.org/10.1016/j.rse.2006.09.007 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=28433 [article]

Efficiency of carrier-phase integer ambiguity resolution for precise GPS positioning in noisy environments / L. Zhu in Journal of geodesy, vol 81 n° 2 (February 2007)  

Public [article]  inJournal of geodesy > vol 81 n° 2 (February 2007) . - pp 149 - 156 Titre : Efficiency of carrier-phase integer ambiguity resolution for precise GPS positioning in noisy environments Type de document : Article/Communication Auteurs : L. Zhu, Auteur ; Y.C. Lai, Auteur ; M. Shah, Auteur ; et al., Auteur Année de publication : 2007 Article en page(s) : pp 149 - 156 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie spatiale [Termes IGN] ambiguïté entière [Termes IGN] brouillage [Termes IGN] bruit (théorie du signal) [Termes IGN] méthode des moindres carrés [Termes IGN] phase GPS [Termes IGN] positionnement par GPS [Termes IGN] résolution d'ambiguïté Résumé : (Auteur) Precise GPS positioning relies on tracking the carrier-phase. The fractional part of carrier-phase can be measured directly using a standard phase-locked loop, but the integer part is ambiguous and the ambiguity must be resolved based on sequential carrier-phase measurements to ensure the required positioning precision. In the presence of large phase-measurement noise, as can be expected in a jamming environment for example, the amount of data required to resolve the integer ambiguity can be large, which requires a long time for any generic integer parameter estimation algorithm to converge. A key question of interest in significant applications of GPS where fast and accurate positioning is desired is then how the convergence time depends on the noise amplitude. Here we address this question by investigating integer least-squares estimation algorithms. Our theoretical derivation and numerical experiments indicate that the convergence time increases linearly with the noise variance, suggesting a less stringent requirement for the convergence time than intuitively expected, even in a jamming environment where the phase noise amplitude is large. This finding can be useful for practical design of GPS-based systems in a jamming environment, for which the ambiguity resolution time for precise positioning may be critical. Copyright Springer Numéro de notice : A2007-048 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-006-0096-y En ligne : https://doi.org/10.1007/s00190-006-0096-y Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=28413 [article]

Exemplaires(2)

Code-barres	Cote	Support	Localisation	Section	Disponibilité
266-07021	RAB	Revue	Centre de documentation	En réserve L003	Disponible
266-07022	RAB	Revue	Centre de documentation	En réserve L003	Disponible

Modeling long-period noise in kinematic GPS applications / A. Borsa in Journal of geodesy, vol 81 n° 2 (February 2007)  

Public [article]  inJournal of geodesy > vol 81 n° 2 (February 2007) . - pp 157 - 170 Titre : Modeling long-period noise in kinematic GPS applications Type de document : Article/Communication Auteurs : A. Borsa, Auteur ; J.B. Minster, Auteur ; B.G. Bills, Auteur ; et al., Auteur Année de publication : 2007 Article en page(s) : pp 157 - 170 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie spatiale [Termes IGN] Bolivie [Termes IGN] bruit (théorie du signal) [Termes IGN] désert [Termes IGN] erreur moyenne quadratique altimétrique [Termes IGN] filtrage du bruit [Termes IGN] GPS en mode cinématique [Termes IGN] problème inverse Résumé : (Auteur) We develop and test an algorithm for modeling and removing elevation error in kinematic GPS trajectories in the context of a kinematic GPS survey of the salar de Uyuni, Bolivia. Noise in the kinematic trajectory ranges over 15 cm and is highly autocorrelated, resulting in significant contamination of the topographic signal. We solve for a noise model using crossover differences at trajectory intersections as constraints in a least-squares inversion. Validation of the model using multiple realizations of synthetic/simulated noise shows an average decrease in root-mean-square-error (RMSE) by a factor of four. Applying the model to data from the salar de Uyuni survey, we find that crossover differences drop by a factor of eight (from an RMSE of 5.6 to 0.7 cm), and previously obscured topographic features are revealed in a plan view of the corrected trajectory. We believe that this algorithm can be successfully adapted to other survey methods that employ kinematic GPS for positioning. Copyright Springer Numéro de notice : A2007-049 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-006-0097-x En ligne : https://doi.org/10.1007/s00190-006-0097-x Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=28414 [article]

Exemplaires(2)

Code-barres	Cote	Support	Localisation	Section	Disponibilité
266-07021	RAB	Revue	Centre de documentation	En réserve L003	Disponible
266-07022	RAB	Revue	Centre de documentation	En réserve L003	Disponible

Least-square variance component estimation / Ali Reza Amiri-Simkooei (2007)  

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Local solutions to inverse problems in geodesy: The impact of the noise covariance structure upon the accuracy of estimation / F. Bauer in Journal of geodesy, vol 81 n° 1 (January 2007)  

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Une topographie plus précise / Françoise de Blomac in SIG la lettre, n° 83 (janvier 2007)

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Le traitement du signal sous Matlab / André Quinquis (2007)

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Error analysis of weekly station coordinates in the DORIS network / Simon D.P. Williams in Journal of geodesy, vol 80 n° 8-11 (November 2006)  

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Estimating the noise in space-geodetic positioning: the case of DORIS / Karine Le Bail in Journal of geodesy, vol 80 n° 8-11 (November 2006)  

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Plate kinematic of Nubia-Somalia using combined DORIS and GPS solution / Jean-Mathieu Nocquet in Journal of geodesy, vol 80 n° 8-11 (November 2006)  

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Searching for Galileo: reception and analysis of signals from GIOVE-A / M.L. Psiaki in GPS world, vol 17 n° 6 (June 2006)

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Évaluation de la qualité des séries temporelles de mesures en géodesie spatiale / Karine Le Bail in Bulletin d'information scientifique et technique de l'IGN, n° 75 (mars 2006)

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GGOS Working Group on Ground Networks Communications / Michael Pearlman (2006)  

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