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Optimierung von Beobachtungsplänen in der Langbasisinterferometrie (VLBI) / H. Steufmehl (1994)

Public Titre : Optimierung von Beobachtungsplänen in der Langbasisinterferometrie (VLBI) Titre original : [Optimisation de la prévision des observations d'interférométrie à très grande base] Type de document : Thèse/HDR Auteurs : H. Steufmehl, Auteur Editeur : Francfort sur le Main : Institut für Angewandte Geodäsie Année de publication : 1994 Collection : DGK - C Sous-collection : Dissertationen num. 406 Importance : 75 p. Format : 21 x 30 cm Note générale : Bibliographie Langues : Allemand (ger) Descripteur : [Vedettes matières IGN] Géodésie spatiale [Termes IGN] données ITGB [Termes IGN] interférométrie à très grande base [Termes IGN] matrice de covariance [Termes IGN] optimisation (mathématiques) [Termes IGN] programmation dynamique Index. décimale : 30.63 Télémétrie laser sur satellite, Télémétrie laser sur lune, VLBI Résumé : (Auteur)Very Long Baseline Interferomerty (VLBI) is a method, which makes use of the radiation of extragalactical radio sources received by radio telescopes. The time difference between the arrival of the signals at two different observing stations is the prime VLBI-observable. When several radio telescopes are linked to a network and have observed different sources for a time interval of normally 24 hours, we speak of a VLBI experiment. The sequence of the sources to be monitored is deter-mined by the observing schedule. In order to obtain the best quality of determination of the target parameters, the variance/covariance matrix of the parameters should have an optimal design. This optimal design depends on the geometric configuration of the observations. Until now, the observations are selected interactively in a time-consuming process and without a precise knowledge of the quality of determination. In this thesis an algorithm is developed which allows the automatic creation of optimized VLBI observing schedules. The analogies between the optimization of geodetic networks and the problem under consideration are dis-cussed and then the problem is presented as a 1 .order design problem where the observing stations must be linked optimally by time delay observations. It is a problem of sequentiel decisions, which can be solved on the basis of the process of dynamic optimization. The problem is analysed and a simplified numerical method of solution suited for implementation in a computer program is derived. i Furthermore, simulated observing schedules from the international observing program IRIS are presented. Some of those schedules have been used in real measurement campaigns. The observing positions have a tendency to accumulate in certain regions of the observable sky. The improvements of the accuracies range between 15% to 20% in comparison to the 'hand-made' schedules. The significance of the new method is given on the one hand by the various possibilities of application while designing new networks and schedules and on the other hand by the much more efficient way of creating obser-ving schedules. Numéro de notice : 28077 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Thèse étrangère Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=63424

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28077-01	30.63	Livre	Centre de documentation	Géodésie	Disponible