Evaluation of GPS L5 and Galileo E1 and E5a Performance for Future Multi Frequency and Multi Constellation GBAS

Kurzfassung

In this paper, we show a performance analysis of different signals from the new Galileo satellites in the E1 and E5a frequency bands as well as GPS L5 signals in DLR’s experimental Ground Based Augmentation System (GBAS). We show results of noise and multipath evaluations of the available Galileo satellites and compare their performance to the currently used GPS L1 and the new GPS L5 signals which were presented in a recent paper. The results show that the raw noise and multipath level of Galileo signals is smaller than of GPS. Even after smoothing, Galileo signals perform somewhat better than GPS and are less sensitive to the smoothing time constant. Another issue to be considered in a future multi frequency system is inter-frequency bias. These biases differ between satellites and depend on satellite and receiver hardware, but they can be determined a priori. With known receiver and antenna configurations, it is possible to correct for these biases and avoid errors introduced by different hardware in the airborne receiver and GBAS ground system. A residual uncertainty associated with the bias correction has to be taken into account. This can be modelled as part of σ_(pr\_gnd).