Understanding limitations of GPS carrier phase frequency transfer on a transatlantic baseline

This work is made in an effort to determine and understand the limitations of GPS carrier-phase frequency transfer between the National Institute of Standards and Technology (NIST) in Boulder, Colorado and the Physikalisch-Technische Bundesanstalt (PTB) in Braunschweig, Germany. We compare two analytical software packages and report on possible reasons for differences in results. Specifically we look at bias fixing, merging routines, data outages, and sampling and analysis period effects. We hope to determine and reduce the contributions of these effects and lower the overall error budget of the carrier-phase GPS comparison technique.