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Future time : opportunities for using optical clocks in GNSS systems / A. Moudrak in Inside GNSS, vol 3 n° 6 (September 2008)
[article]
Titre : Future time : opportunities for using optical clocks in GNSS systems Type de document : Article/Communication Auteurs : A. Moudrak, Auteur ; H. Klein, Auteur ; Bernd Eissfeller, Auteur Année de publication : 2008 Article en page(s) : 6 p. ; pp 45 - 50 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie spatiale
[Termes IGN] Global Navigation Satellite System
[Termes IGN] horloge
[Termes IGN] secteur spatialRésumé : (Auteur) Satellite clock prediction accuracy may be considerably improved with the emerging optical clock technology. To maximize the performance benefits, optical clocks should be placed onboard the satellites (and on ground to generate the system time). Implementation of optical clocks to keep the system time could increase the accuracy of Galileo timing service (dissemination of UTC) and keep the UTC prediction function within the system. In this case, dependence on an external infrastructure such as the TSP may be reduced. If other contributions to the error budget (mainly, the multipath) were reduced, we might anticipate further significant benefits to user positioning accuracy from improved clock technology, for instance, through exploitation of carrier phase techniques. Placing better clocks on satellites will reduce the need for frequent updates, which will simplify the requirements on ground systems and also reduce costs. If update links were to fail for a significant amount of time, having very good clocks in the space segment would reduce the rate of degradation of the service to users on the ground. Copyright Gibbons Media & Research LLC Numéro de notice : A2008-678 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article DOI : sans Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=33531
in Inside GNSS > vol 3 n° 6 (September 2008) . - 6 p. ; pp 45 - 50[article]Documents numériques
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Future time ... - pdf éditeurAdobe Acrobat PDF Potential accuracy of image orientation of small satellites: a case study of CHRIS/Proba data / Ahmed Shaker in Photogrammetric record, vol 23 n° 123 (September - November 2008)
[article]
Titre : Potential accuracy of image orientation of small satellites: a case study of CHRIS/Proba data Type de document : Article/Communication Auteurs : Ahmed Shaker, Auteur ; J. Nichol, Auteur ; M. Wong, Auteur Année de publication : 2008 Conférence : ISPRS 2007, High-Resolution Earth Imaging for Geospatial Information workshop 29/05/2007 01/06/2007 Hanovre Allemagne Article en page(s) : pp 275 - 289 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Photogrammétrie spatiale
[Termes IGN] angle de visée
[Termes IGN] correction géométrique
[Termes IGN] espace image
[Termes IGN] espace objet
[Termes IGN] géoréférencement
[Termes IGN] Hong-Kong
[Termes IGN] image hyperspectrale
[Termes IGN] image PROBA-CHRIS
[Termes IGN] minisatellite
[Termes IGN] modèle empirique
[Termes IGN] modèle stéréoscopique
[Termes IGN] montagne
[Termes IGN] orientation d'image
[Termes IGN] point d'appui
[Termes IGN] précision géométrique (imagerie)Résumé : (Auteur) The new technology of small satellites (microsatellites) opens a new era in satellite observation of the earth. Small satellites such as ESA's Project for On-Board Autonomy (Proba), launched on 22nd October 2001, are of interest due to their low cost, flexibility of positioning, and capability for multiangular scanning in both across-track and along-track directions. Proba's Compact High Resolution Imaging Spectrometer (CHRIS) provides multidirectional, as well as hyperspectral, data at 18 m resolution and is supplied mainly to the scientific community for experimental environmental applications. This research evaluates the use of various empirical mathematical models for small satellite orientation and terrain modelling using the multidirectional viewing capabilities of CHRIS data. Geometric correction and co-registration of multiangle images is essential for their use for data extraction. Ideally, rigorous mathematical models should be formulated which precisely describe the satellite motion and represent the relationship between the image and the object spaces. The use of rigorous mathematical models has not been fully investigated using CHRIS/Proba data, because the satellite information provided is not adequate for rigorous sensor modelling. In this paper, several alternative empirical models are tested for the orientation and 3D geopositioning of CHRIS sensor images. The images used in this study cover extremely mountainous terrain in central Hong Kong. A set of five images from CHRIS/Proba taken in December 2005 from different angles are used to test the applicability of different forms of the empirical models for 3D geopositioning. The accuracy of the models is tested for different numbers and distribution of ground control points (GCPs) using different combinations of observation angles and base-to-height ratios. The results obtained show high integrity of the models used for CHRIS/Proba image orientation. In some cases, accuracy better than 2 pixels can be achieved using a modest number of GCPs. Copyright RS&PS + Blackwell Publishing Numéro de notice : A2008-393 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Article DOI : 10.1111/j.1477-9730.2008.00490.x En ligne : https://doi.org/10.1111/j.1477-9730.2008.00490.x Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=29386
in Photogrammetric record > vol 23 n° 123 (September - November 2008) . - pp 275 - 289[article]Réservation
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Code-barres Cote Support Localisation Section Disponibilité 106-08031 RAB Revue Centre de documentation En réserve L003 Disponible Galileo gioves come off: military after all / Anonyme in GPS world, vol 19 n° 8 (August 2008)
[article]
Titre : Galileo gioves come off: military after all Type de document : Article/Communication Auteurs : Anonyme, Auteur Année de publication : 2008 Article en page(s) : pp 10 - 12 Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie spatiale
[Termes IGN] armée
[Termes IGN] GIOVE (satellite)
[Termes IGN] utilisateur militaireNuméro de notice : A2008-323 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article DOI : sans Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=29316
in GPS world > vol 19 n° 8 (August 2008) . - pp 10 - 12[article]Réservation
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Code-barres Cote Support Localisation Section Disponibilité 067-08081 RAB Revue Centre de documentation En réserve L003 Disponible Geoeye's next-generation imaging satellite / J. Croft in Geoinformatics, vol 11 n° 4 (01/06/2008)
[article]
Titre : Geoeye's next-generation imaging satellite Type de document : Article/Communication Auteurs : J. Croft, Auteur Année de publication : 2008 Article en page(s) : pp 18 - 23 Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Acquisition d'image(s) et de donnée(s)
[Termes IGN] aide à la décision
[Termes IGN] Geoeye
[Termes IGN] géoréférencement
[Termes IGN] image aérienne
[Termes IGN] image Geoeye
[Termes IGN] précision métrique
[Termes IGN] simulation d'image
[Termes IGN] téléscopeRésumé : (Auteur) In the coming months, insurance companies will have access to commercial satellite images precise enough to determine whether an insured homeowner living in a fire-prone area like southern California should thin the brush in his backyard to prevent the spread of a forest fire. Defense and intelligence communities will have access to imagery that is an ideal tool and infrastructure on the ground. These sorts of uses are mere snapshots of what commercial imagery provider Geoeye (Dulles, va) envisions for its next-generation Geoeye-1 Earth-imaging satellite, slated for launch later this year. Copyright GEOinformatics Numéro de notice : A2008-239 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Article DOI : sans Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=29234
in Geoinformatics > vol 11 n° 4 (01/06/2008) . - pp 18 - 23[article]Réservation
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Code-barres Cote Support Localisation Section Disponibilité 262-08041 SL Revue Centre de documentation Revues en salle Disponible GNSS update / Huibert-Jan Lekkerkerk in Geoinformatics, vol 11 n° 4 (01/06/2008)
[article]
Titre : GNSS update Type de document : Article/Communication Auteurs : Huibert-Jan Lekkerkerk, Auteur Année de publication : 2008 Article en page(s) : pp 14 - 17 Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie spatiale
[Termes IGN] constellation BeiDou
[Termes IGN] constellation Galileo
[Termes IGN] constellation GLONASS
[Termes IGN] constellation GPS
[Termes IGN] Global Navigation Satellite System
[Termes IGN] satellite de positionnementRésumé : (Auteur) On february 22nd 1978 the first block 1 satellite : Navstar 1, was launched which means that february 22nd of this year marked the 30th anniversary of GPS. Navstar, now called GPS has been a military project from the start although there seems to be a gradual shift in government policy giving the civilian sector an increasing voice in GPS. Copyright GEOinformatics Numéro de notice : A2008-238 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article DOI : sans Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=29233
in Geoinformatics > vol 11 n° 4 (01/06/2008) . - pp 14 - 17[article]Réservation
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Code-barres Cote Support Localisation Section Disponibilité 262-08041 SL Revue Centre de documentation Revues en salle Disponible n° 10 - 01/06/2008 - Spécial Spatial (Bulletin de Le magazine de l'observatoire de Paris) / Observatoire de ParisPermalinkGIOVE-B on the ai r: understanding Galileo's new signals / G. Gao in Inside GNSS, vol 3 n° 4 (May - June 2008)PermalinkAssimilation of remote sensed data for improved latent and sensible heat flux prediction: a comparative synthetic study / R. Pipunic in Remote sensing of environment, vol 112 n° 4 (15/04/2008)PermalinkLength-of-day and space-geodetic determination of the Earth's variable gravity field / G. Bourda in Journal of geodesy, vol 82 n° 4-5 (April - May 2008)PermalinkGALILEO validation: the validation message / M. Tossaint in GPS world, vol 19 n° 2 (February 2008)PermalinkGOCE : obtaining a portrait of Earth's most intimate features / M. Drinkwater in ESA bulletin, n° 133 (February 2008)PermalinkGOCE's measurements of the gravity field and beyond / R. Floberghaben in ESA bulletin, n° 133 (February 2008)PermalinkPermalinkAnalysis of 13 years (1993-2005) of Satellite Laser Ranging data on the two LAGEOS satellites for Terrestrial Reference Frames and Earth Orientation Parameters / David Coulot (2008)PermalinkProceedings of the 15th international workshop on laser ranging, Canberra, Australia, 15 - 20 October 2006 / J. Luck (2008)Permalink