Abstract

FERNANDA CAMISAY, Maria; STRIEWE, Esteban  and  MACKERN, María Virginia. Reference frames in real time satellite positioning. Geoacta [online]. 2013, vol.38, n.2, pp.183-193. ISSN 1852-7744.

Real time (RT) satellite positioning services offered by the latinamerican countries are using the Internet Protocol NTRIP (Networked Transport of RTCM via Internet Protocol) for transmitting differential corrections from GNSS permanent stations (Servers-NTRIP). Users can be positioned with precision at the moment of measurement and get the coordinates in the reference frame implicit in the base station coordinates from which the corrections was received. Therefore, a correct configuration of RT services, will ensure users not only to refer to the appropriate reference frame but also obtain optimal precision in the resulting coordinates. Then the objective of this work was to analyze the current situation of the services offered in Brazil, Uruguay and Argentina. The configuration of the reference stations as well as the regional caster has been studied to accomplish such object. Each RTCM messages transmitted from server stations was also analyzed in detail. The reference frames of the coordinates were verified, as well as the reference to it in the publishing site. It was found that a user does not have information of the framework at the time of measurement. Results of experiences performed in the Uruguay - Argentina border zone were presented. Experimental streams was created from the same station on three different reference frames: POSGAR 2007 (Arg) , ROU 98 (Uru.) and weekly SIRGAS coordinates. These results quantify the influence of using different reference frames in the accuracy of the real time positioning.

Keywords : GNSS; Real Time; NTRIP; Reference Frame; Epoch.

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