Combined GPS/GLONASS Analysis at the Center for Orbit Determination in
Europe (CODE)

Stefan Schaer (AIUB, Berne, Switzerland)

Since the beginning of May 2003, the CODE analysis center has been
computing a rapid orbit product for both the GPS and the GLONASS
satellite constellation. In the meantime, this is also the case with
respect to our final product (since 8 June 2003) as well as our
ultra-rapid orbit product (officially since 30 July 2003). GPS and
GLONASS orbits are generated at the same time in a rigorous GNSS
analysis. We will give an overview of our GNSS analysis activities and
discuss issues we consider relevant for a combined analysis of two or
more navigation satellite systems. This includes issues related to
retrieval of global total electron content (TEC) information and
estimation of phase-consistent GNSS clock offsets.