Galileo Double-difference Signal Measured
Researchers from TU Delft have succeeded in simultaneously tracking signals from two Galileo test satellites orbiting the earth. Analyses of the measurements show that the accuracy of the Galileo system is better than with GPS, according to researchers Christiaan Tiberius, Hans van der Marel and Peter Teunissen of the Faculty of Aerospace Engineering.
These results constitute proof from the field that Galileo works, and performs to the level of quality and reliability that are claimed for it. In the evening and night of 6 July 2008, researchers set up two identical receivers in open countryside in Delfland. They collected ranging measurements to 12 GPS satellites, two geostationary European Geostationary Navigation Overlay Service (EGNOS) satellites and two Galileo satellites, GIOVE-A and GIOVE-B. The double-difference measurements were made during a 90-minute window when both GIOVE-A and GIOVE-B were visible. On the basis of these measurements it was possible to precisely estimate the Galileo double-difference carrier phase cycle ambiguity and fix it to an integer value with a high degree of confidence. This makes it possible to measure distances to the Galileo satellites to the nearest millimetre, which is essential in high-precision applications.
These results produced by TU Delft will pave the way for the development of advanced applications for Galileo in the field of combined position and timing calculation. Reliable satellite data can be used, for example, to land aircraft automatically, to survey, to identify tectonic movements and to forecast the weather.
The results were achieved in close cooperation with Septentrio Satellite Navigation of Leuven (Belgium). The researchers participating in this project are Christiaan Tiberius, Hans van der Marel and Peter Teunissen of TU Delft, and Jean-Marie Sleewaegen and Frank Boon of Septentrio.
