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High precision GPS processing in kinematic mode / Marc Cocard (1995)

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Titre :	High precision GPS processing in kinematic mode
Type de document :	Monographie
Auteurs :	Marc Cocard, Auteur
Editeur :	Zurich : Schweizerischen Geodatischen Kommission / Commission Géodésique Suisse
Année de publication :	1995
Collection :	Geodätisch-Geophysikalische Arbeiten in der Schweiz, ISSN 0257-1722 num. 52
Importance :	140 p.
Format :	21 x 30 cm
Note générale :	Bibliographie
Langues :	Anglais (eng)
Descripteur :	[Vedettes matières IGN] Géodésie spatiale [Termes IGN] ambiguïté entière [Termes IGN] données GPS [Termes IGN] GPS en mode cinématique [Termes IGN] mesurage de pseudo-distance [Termes IGN] orbitographie [Termes IGN] résolution d'ambiguïté [Termes IGN] traitement de données GNSS
Index. décimale :	30.61 Systèmes de Positionnement par Satellites du GNSS
Résumé :	(Auteur) This report deals with the calculation of highly accurate trajectories of moving vehicles, and of air planes in particular, from differential GPS measurements processed in the offline mode. In the last few years the Global Positioning System (GPS) has become the most powerful navigation system worldwide. Although it was developed by the American Department of Defense (DoD) and is, therefore, primarily designated for military use, the number of civilian users is rapidly increasing from day to day. Based on satellite measurements, GPS allows instantaneous positioning accurate to within 100200 meters. [Remondi, 1984] bas shown that differential processing of phase measurements allows improvement of position accuracy to few centimeters. There are numerous applications for spatial trajectories calculated with such high quality accuracy: e.g. their integration in photogrammetric aerotriangulation allows considerable reduction of the number of control points on the ground. Also in airborne gravimetry new horizons are being opened by using GPS. A software system for processing kinematic data in the offline mode has been developed. Its key features are presented first. A robust and flexible approach using simultaneously phase and codemeasurements in a differential way is used. For the computation the differences between the code and phase information, measured by the roving receiver as well as by a fixed reference receiver, are used in order to reduce the systematic errors, which affect both receivers in a similar way. The main differences between the phase and the code data are (a) noise (decimeters to meters for the code, millimeters for the phase) and (b) the unknown ambiguities in the phase measurements, which are known to be integer values. Processing is carried out in two steps: firstly a least squares adjustment is applied in order to determine the timeinvariant parameters, using the entire data set. Parameters which are considered as invariant are the ambiguities and the coordinates of the roving receiver during stationary periods. Next, the integer values of the ambiguities are determined. In a second step the trajectory is reprocessed by introducing the known ambiguities. The key problem in obtaining highaccuracy trajectories consists in making reliable identification of the integervalued ambiguities. It is demonstrated that a conventional sigma dependent rounding strategy, commonly used in static applications, is still a useful tool in offline kinematic processing. In addition, a more powerful search strategy has been analyzed and simulations show that under ideal conditions the integer values of the ambiguities can be retrieved within one epoch worth of dualfrequency measurements. These simulated results have been validated by real data. With increasing distance between the roving and the reference receiver a stochastic modelling of the ionospheric path delay gave good results but also showed the limitation of instantaneous ambiguity resolution. Using GPS data of good quality trajectories with an accuracy of a few centimeters were recovered. With increasing distance between rover and reference station (up to 100 kilometers), however, all ambiguities could not always be resolved and the quality of the resulting trajectories deteriorates to some decimeters. But even in this case it was possible to derive the velocity and acceleration of the aircraft with high accuracy from the coordinates.
Numéro de notice :	12607
Affiliation des auteurs :	non IGN
Thématique :	POSITIONNEMENT
Nature :	Monographie
En ligne :	https://www.sgc.ethz.ch/sgc-volumes/sgk-52.pdf
Format de la ressource électronique :	URL
Permalink :	https://documentation.ensg.eu/index.php?lvl=notice_display&id=54706

Exemplaires(2)

Code-barres	Cote	Support	Localisation	Section	Disponibilité
12607-01	30.61	Livre	Centre de documentation	Géodésie	Disponible
12607-02	30.61	Livre	Centre de documentation	Géodésie	Disponible

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