  Today, the Global Navigation Satellite Systems, used as global positioning
systems, are the GPS and the GLONASS. They are based on a Newtonian model and
hence they are only operative when several relativistic effects are taken into
account. The most important relativistic effects (to order 1/c^2) are: the
Einstein gravitational blue shift effect of the satellite clock frequency
(Equivalence Principle of General Relativity) and the Doppler red shift of
second order, due to the motion of the satellite (Special Relativity).
  On the other hand, in a few years the Galileo system will be built, copying
the GPS system unless an alternative project is designed. In this work, it will
be also shown that the SYPOR project, using fully relativistic concepts, is an
alternative to a mere copy of the GPS system. According to this project, the
Galileo system would be exact and there would be no need for relativistic
corrections.
