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Titre : Simulating inertial/GNSS hybrid Type de document : Article/Communication Auteurs : M. Gallot, Auteur ; P. Dutot, Auteur ; C. Sajous, Auteur Année de publication : 2012 Article en page(s) : pp 38 - 43 Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie spatiale
[Termes IGN] brouillage
[Termes IGN] couplage GNSS-INS
[Termes IGN] positionnement par GNSS
[Termes IGN] récepteur Galileo
[Termes IGN] récepteur GPS
[Termes IGN] rendu réaliste
[Termes IGN] simulateur de volRésumé : (Auteur) A new hardware assessment tool automates testing and mission replay, managing military GPS receiver input and output data, with an operational implementation and with a better control of initialization conditions, especially direct P(Y) acquisition. The test bench drives a GPS/Galileo simulator, a digital jammer, and software programs for visibility computation based on terrain modeling, and for multipath generation on 3D renderings. Numéro de notice : A2012-238 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article DOI : sans Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=31684
in GPS world > vol 23 n° 5 (May 2012) . - pp 38 - 43[article]Réservation
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Code-barres Cote Support Localisation Section Disponibilité 067-2012051 RAB Revue Centre de documentation En réserve L003 Disponible Simulation study of a follow-on gravity mission to GRACE / B. Loomis in Journal of geodesy, vol 86 n° 5 (May 2012)
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[article]
Titre : Simulation study of a follow-on gravity mission to GRACE Type de document : Article/Communication Auteurs : B. Loomis, Auteur ; R. Nerem, Auteur ; Scott B. Luthcke, Auteur Année de publication : 2012 Article en page(s) : pp 319 - 335 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie physique
[Termes IGN] champ de pesanteur terrestre
[Termes IGN] crénelage
[Termes IGN] données GRACE
[Termes IGN] masse de la Terre
[Termes IGN] simulationRésumé : (Auteur) The gravity recovery and climate experiment (GRACE) has been providing monthly estimates of the Earth’s time-variable gravity field since its launch in March 2002. The GRACE gravity estimates are used to study temporal mass variations on global and regional scales, which are largely caused by a redistribution of water mass in the Earth system. The accuracy of the GRACE gravity fields are primarily limited by the satellite-to-satellite range-rate measurement noise, accelerometer errors, attitude errors, orbit errors, and temporal aliasing caused by un-modeled high-frequency variations in the gravity signal. Recent work by Ball Aerospace & Technologies Corp., Boulder, CO has resulted in the successful development of an interferometric laser ranging system to specifically address the limitations of the K-band microwave ranging system that provides the satellite-to-satellite measurements for the GRACE mission. Full numerical simulations are performed for several possible configurations of a GRACE Follow-On (GFO) mission to determine if a future satellite gravity recovery mission equipped with a laser ranging system will provide better estimates of time-variable gravity, thus benefiting many areas of Earth systems research. The laser ranging system improves the range-rate measurement precision to ~0.6 nm/s as compared to ~0.2 ?m/s for the GRACE K-band microwave ranging instrument. Four different mission scenarios are simulated to investigate the effect of the better instrument at two different altitudes. The first pair of simulated missions is flown at GRACE altitude (~480 km) assuming on-board accelerometers with the same noise characteristics as those currently used for GRACE. The second pair of missions is flown at an altitude of ~250 km which requires a drag-free system to prevent satellite re-entry. In addition to allowing a lower satellite altitude, the drag-free system also reduces the errors associated with the accelerometer. All simulated mission scenarios assume a two satellite co-orbiting pair similar to GRACE in a near-polar, near-circular orbit. A method for local time variable gravity recovery through mass concentration blocks (mascons) is used to form simulated gravity estimates for Greenland and the Amazon region for three GFO configurations and GRACE. Simulation results show that the increased precision of the laser does not improve gravity estimation when flown with on-board accelerometers at the same altitude and spacecraft separation as GRACE, even when time-varying background models are not included. This study also shows that only modest improvement is realized for the best-case scenario (laser, low-altitude, drag-free) as compared to GRACE due to temporal aliasing errors. These errors are caused by high-frequency variations in the hydrology signal and imperfections in the atmospheric, oceanographic, and tidal models which are used to remove unwanted signal. This work concludes that applying the updated technologies alone will not immediately advance the accuracy of the gravity estimates. If the scientific objectives of a GFO mission require more accurate gravity estimates, then future work should focus on improvements in the geophysical models, and ways in which the mission design or data processing could reduce the effects of temporal aliasing. Numéro de notice : A2012-241 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-011-0521-8 Date de publication en ligne : 28/10/2011 En ligne : https://doi.org/10.1007/s00190-011-0521-8 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=31687
in Journal of geodesy > vol 86 n° 5 (May 2012) . - pp 319 - 335[article]Réservation
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Code-barres Cote Support Localisation Section Disponibilité 266-2012051 RAB Revue Centre de documentation En réserve L003 Disponible Ionospheric artifacts in simultaneous L-band InSAR and GPS observations / J. Chen in IEEE Transactions on geoscience and remote sensing, vol 50 n° 4 (April 2012)
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[article]
Titre : Ionospheric artifacts in simultaneous L-band InSAR and GPS observations Type de document : Article/Communication Auteurs : J. Chen, Auteur ; H. Zebker, Auteur Année de publication : 2012 Article en page(s) : pp 11227 - 1239 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Traitement d'image radar et applications
[Termes IGN] artefact
[Termes IGN] bande L
[Termes IGN] image ALOS-PALSAR
[Termes IGN] image radar moirée
[Termes IGN] interféromètrie par radar à antenne synthétique
[Termes IGN] propagation ionosphérique
[Termes IGN] teneur totale en électronsRésumé : (Auteur) Phase artifacts in interferometric synthetic aperture radar (InSAR) images frequently degrade the interpretability of the phase and correlation signatures of terrain. Often, these distortions are attributed to spatially variable ionospheric propagation delays at two different SAR acquisition times. We present here L-band InSAR data from Iceland, California, and Hawaii. The California and Hawaii interferograms show no significant ionospheric artifacts, while the Iceland interferogram shows a maximum misregistration of three pixels in the azimuth direction, which leads to severe phase decorrelation artifacts in the InSAR image. We relate the misregistration of complex pixels seen in the interferograms to the gradient of the ionospheric total electron content (TEC) observed by global positioning system (GPS) data and confirm that indeed the phase artifacts in the Iceland interferogram are due to dispersive ionospheric propagation rather than other decorrelation factors such as neutral atmospheric delays. We develop a method to measure the spatial TEC variation at synthetic aperture length scales using dual-frequency GPS carrier phase data. We solve for the GPS data ambiguities using a low-resolution ionosphere reference derived from either available ionospheric observations or the GPS carrier phase data themselves. GPS observations show directly the level of ionospheric variability, and the spatial TEC gradient as observed by GPS predicts the misregistration of complex pixels in interferograms in all three areas. This confirmation of the cause of the image artifacts suggests that they can be routinely corrected from the InSAR data alone, provided that the sensor measures the change in TEC along the radar swath. Numéro de notice : A2012-136 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1109/TGRS.2011.2164805 Date de publication en ligne : 06/10/2011 En ligne : https://doi.org/10.1109/TGRS.2011.2164805 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=31584
in IEEE Transactions on geoscience and remote sensing > vol 50 n° 4 (April 2012) . - pp 11227 - 1239[article]Réservation
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Code-barres Cote Support Localisation Section Disponibilité 065-2012041 RAB Revue Centre de documentation En réserve L003 Disponible 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)
[article]
Titre : Ionospheric scintillations: How irregularities in electron density perturb satellite navigation systems Type de document : Article/Communication Auteurs : Satellite-based augmentation system ionospheric working group, Auteur Année de publication : 2012 Article en page(s) : pp 44 - 50 Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Traitement du signal
[Termes IGN] distorsion du signal
[Termes IGN] effet atmosphérique
[Termes IGN] Global Navigation Satellite System
[Termes IGN] modulation du signal
[Termes IGN] perturbation ionosphérique
[Termes IGN] scintillation
[Termes IGN] signal GNSS
[Termes IGN] système d'extensionRésumé : (Editeur) In this month’s column, the international Satellite-Based Augmentation Systems Ionospheric Working Group presents an abridged version of their recently completed white paper on the effect of ionospheric scintillations on GNSS and the associated augmentation systems. Numéro de notice : A2012-134 Affiliation des auteurs : non IGN Thématique : IMAGERIE/POSITIONNEMENT Nature : Article DOI : sans Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=31582
in GPS world > vol 23 n° 4 (April 2012) . - pp 44 - 50[article]Réservation
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Code-barres Cote Support Localisation Section Disponibilité 067-2012041 RAB Revue Centre de documentation En réserve L003 Disponible Personal privacy jammers: Locating Jersey PPDs jamming GBAS [Ground-Based Augmentation System] safety-of-life signals / J. Grabowski in GPS world, vol 23 n° 4 (April 2012)
[article]
Titre : Personal privacy jammers: Locating Jersey PPDs jamming GBAS [Ground-Based Augmentation System] safety-of-life signals Type de document : Article/Communication Auteurs : J. Grabowski, Auteur Année de publication : 2012 Article en page(s) : pp 28 - 36 Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Traitement du signal
[Termes IGN] aéroport
[Termes IGN] appareil portable
[Termes IGN] brouillage
[Termes IGN] dégradation du signal
[Termes IGN] New Jersey (Etats-Unis)
[Termes IGN] PDA
[Termes IGN] signal GPS
[Termes IGN] téléphonie mobileRésumé : (Auteur) When jamming interfered with GPS signals at Newark Airport, a three-month effort determined that low-power, mobile personal-privacy devices were responsible. This article describes how they were found and outlines how the observable parameters of such devices encompass a wide variation in RF spectra and internal modulation. Numéro de notice : A2012-133 Affiliation des auteurs : non IGN Thématique : IMAGERIE/POSITIONNEMENT Nature : Article DOI : sans Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=31581
in GPS world > vol 23 n° 4 (April 2012) . - pp 28 - 36[article]Réservation
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Code-barres Cote Support Localisation Section Disponibilité 067-2012041 RAB Revue Centre de documentation En réserve L003 Disponible GPS snow depth meter with geometry-free linear combinations of carrier phases / M. Ozeki in Journal of geodesy, vol 86 n° 3 (March 2012)
PermalinkFiltering and segmentation of polarimetric SAR data based on binary partition trees / A. Alonso-Gonzalez in IEEE Transactions on geoscience and remote sensing, vol 50 n° 2 (February 2012)
PermalinkA nonlocal SAR image denoising algorithm based on LLMMSE wavelet shrinkage / S. Parrilli in IEEE Transactions on geoscience and remote sensing, vol 50 n° 2 (February 2012)
PermalinkCorrection du flou de mouvement sur les images prises de nuit par le STEREOPOLIS / Vincent Daval (2012)
PermalinkEntwicklung eines Kalman-Filters zur Bestimmung kurzzeitiger Variationen des Erdschwerefeldes aus daten der Satellitenmission GRACE / E. Kurtenbach (2012)
PermalinkFlexible dataset combination and modelling by domain decomposition approaches / Isabelle Panet (2012)
PermalinkInterference & Einstein: GNSS update / Huibert-Jan Lekkerkerk in Geoinformatics, vol 15 n° 1 (01/01/2012)
PermalinkKnow your enemy: signal characteristics of civil GPS jammers / R. Mitch in GPS world, vol 23 n° 1 (January 2012)
PermalinkStrategies to mitigate aliasing of loading signals while estimating GPS frame parameters / Xavier Collilieux in Journal of geodesy, vol 86 n° 1 (January 2012)
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