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Envisat safety launched: Europe's green machine is now in orbit! / Gordon Petrie in Geoinformatics, vol 5 n° 3 (01/04/2002)

Public [article]  inGeoinformatics > vol 5 n° 3 (01/04/2002) . - pp 6 - 7 Titre : Envisat safety launched: Europe's green machine is now in orbit! Type de document : Article/Communication Auteurs : Gordon Petrie, Auteur Année de publication : 2002 Article en page(s) : pp 6 - 7 Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Technologies spatiales [Termes IGN] environnement [Termes IGN] ENVISAT [Termes IGN] Medium Resolution Imaging Spectrometer Résumé : (Auteur) To the great relief of the European Space Agency (ESA), Arianespace and European taxpayers and the delight of numerous European scientists, Envisat was launched and placed safely into its correct orbit during the early hours of friday, 1st march. As discussed in the cover story in the last issue of Geoinformatics, the main purpose of Envisat (= Environmental Satellite) is to obtain comprehensive information about many aspects of the Earth's land and sea surfaces and its atmosphere. So basically the huge satellite has been given a truly "green" agenda covering the acquisition of many types of scientific data for global monitoring, which ESA hopes can be collected by Envisat over its designed life of five years. Howerver its AATSR and MERIS optical imagers and its ASAR radar imager should also provide image data that is useful to many people working in the geoinformatics field. Though, within this context, it should be realised that the images acquired by Envisat will only have medium to coarse ground resolution values - since the satellite's instruments are designed mainly to operate on a global, continental or regional scale. Numéro de notice : A2002-090 Affiliation des auteurs : non IGN Thématique : IMAGERIE/POSITIONNEMENT Nature : Article DOI : sans Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=22005 [article]

Exemplaires(1)

Code-barres	Cote	Support	Localisation	Section	Disponibilité
262-02031	SL	Revue	Centre de documentation	Revues en salle	Disponible

GPS limitations and vulnerabilities / K. de Jong in Geoinformatics, vol 5 n° 3 (01/04/2002)

Public [article]  inGeoinformatics > vol 5 n° 3 (01/04/2002) . - pp 22 - 23 Titre : GPS limitations and vulnerabilities Type de document : Article/Communication Auteurs : K. de Jong, Auteur Année de publication : 2002 Article en page(s) : pp 22 - 23 Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie spatiale [Termes IGN] brouillage [Termes IGN] Global Positioning System [Termes IGN] instrument de mesure [Termes IGN] interférence [Termes IGN] positionnement par GPS [Termes IGN] récepteur GPS Résumé : (Auteur) The Global Positioning System (GPS) has come into widespread use both the military and the civil community. There is a growing awareness of the limitations and vulnerabilities of the GPS signals, system provider and user equipement. These limitations not only affect the accuracy of the system, but also its reliability, integrity and availability. A number of ground-and space-based augmentation sytems have been implemented to overcome or reduce these limitations. The augmentation systems provide differential corrections to improve positioning accuracy and integrity messages to inform a user wether or not it is safe to use GPS for positioning and timing. Despite these augementations, however, GPS remains vulnerable to a number of intentional and unintotional disruptions. These disruptions range from radio frequency interference to even intentional physical damage to the system. In September 2001 the US Department of Transportation released a study on the vulnerabilities of GPS. This study is available from www.naven.uscg.gov. Copyright Geoinformatics. Numéro de notice : A2002-091 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article DOI : sans Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=22006 [article]

Exemplaires(1)

Code-barres	Cote	Support	Localisation	Section	Disponibilité
262-02031	SL	Revue	Centre de documentation	Revues en salle	Disponible