Precise Positioning in Real-Time using Navigation Satellites and Telecommunication

Abstract- The paper gives an overview about the principles of DGNSS and RTK positioning for navigation purpose. Special attention is given to the data transfer using GSM, GPRS and in future UMTS. The need for special data transmission formats is described in more detail, especially the benefits of using the new RTCM 3.0 protocol as a correction data format for transmission via GPRS is explained. 1 Principles of DGNSS and RTK 1.1 Satellite positioning and navigation Satellite positioning has been used for the past 20 years, but accuracy of positioning by satellites with a stand-alone receiver is still limited. Today, there are different possibilities to use satellites for positioning and navigation: not only the well-known American system GPS, but also combinations with the Russian system GLONASS or in future with the European system GALILEO. As a generic term we use GNSS (Global Navigation Satellite System) for these satellite systems. The calculation of a position is based on code pseudoranges and carrier phase measurements depending on the required accuracy. As in all surveying procedures, inaccuracies and even errors also occur in GNSS positioning which impair the measured values. These effects can be eliminated by the formation of differences. Using Differential GNSS (DGNSS) techniques, a GNSS reference station is installed temporarily on a known position, which calculates correction parameters and sending them to a mobile GNSS rover. In this way the accuracy will be improved