Article,
Interference Computations Between GPS and Galileo
Proc. of the ION GNSS Conf., (2005)
Abstract
After giving an overview of the baseline in all the bands, the most
outstanding characteristics and figures of Galileo will be outlined
and compared with GPS. The main objec-tive of this paper is to show
the common interference that GPS and the Galileo signals are expected
to have in the future. Of special interest is the intersystem interference
that GPS will suffer due to the Galileo signals and vice versa. The
intersystem interference will be computed according to the methodology
for GPS/Galileo radio frequency compatibility which was commonly
agreed on by the United States and the European Union in June 2004.
A great effort has been put in the computation of the ground received
power for every point in time as well as for every point on the earth
grid. In addition to the smoothed spectra approach that is used in
this agreement more accurate simulations will be per-formed in this
work accounting for the influence of the codes onto the spectra.
Thus, in order to have a more real-istic insight into the problematic,
the real impact of the codes will be considered. This will permit
to show how much the expected values of degradation change with respect
to the assumption of ideal codes. Further simulations have been carried
out to account also for the effects induced to intersystem interference
that are caused by augmentation systems, i.e. SBAS. Intersystem interferences
will be computed for signals where Galileo and GPS are sharing the
band. As we will see, in comparison to the baseline signal BOC(1,1),
the candidate optimized GALILEO L1 OS signal 7 is shown to have
lower levels of interference with GPS C/A. For the computation of
the interference a simulation tool in C++ was programmed. A verification
of the simulation results is given by the outputs of the institute's
software receiver 8. The results of both simulation approaches
show good compliance with each other.
