GPS/GALILEO compatibility
From INVESaTWIKI
GPS/GALILEO compatibility
Until now, compatibility between GALILEO and GPS has become a common understanding during definition and development of GALILEO. It is
a fundamental requirement for both providing a maximum of added-value to the end user, and enabling European industry access to world-wide
markets. However, there is still some scepticism in the downstream industry whether and how compatibility will be achieved.
Compatibility in this context might be defined that the GALILEO signals allow services that enabling a substitution of current GPS services. According
to the available GALILEO documentation this will be the case (with an exception in the field of military applications). Viewed from this
very high abstraction level the GALILEO system is backward compatible to the GPS system.
From the business point of view this might mean that all applications currently in use with GPS can be substituted by GALILEO. As a consequence
from this the GPS systems would no longer be required. Because this does not lead to a fascinating new view another approach for the
definition of the term compatibility should be used, i.e. compatibility in terms of interoperability. Interoperability would provide coexistence of
both systems with potential increased value. The following list names a few points where interoperability between GPS and GALILEO might be
of advantage:
- Accuracy: it should be possible to develop receivers that process GPS and GALILEO signals in a way that the position accuracy is increased. Especially the calculation of positioning solutions that use GPS and GALILEO satellites in combination might result in reasonable fixes where one single system (GPS or GALILEO) does not succeed. This may eliminate the frequently observed 3 or 4 satellite situation that produces fixes which are not very trustworthy;
- Reliability: the same as stated above for accuracy applies also for reliability;
- Technical interoperability: It is very likely that combined GPS/GALILEO receivers will show up on the market. Mobile communication handsets and automotive applications are the largest markets to be expected for such combined receivers. In such mass volume markets interoperability has to be provided already on basic component level such as the RF section of the chipset or the antenna to be used to allow small size and low cost receivers.
As a conclusion out of this the following approach for compatibility and/or interoperability gives the results: a combined receiver that is able to process GPS and GALILEO signals in a manner that satellite signals from both sources are used to calculate a fix. Notably for mass volume applications this receiver shall be built on one GNSS chipset only and use one single antenna (preferably a standard GPS antenna). [1]
References
[1] G.Dippel-Hens (GALILEAN working group report)
"GNSS business issues".
