GPS and Galileo UTC time distribution

Precise timing is an inherent part of Global Navigation Satellite Systems (GNSS) like the Global Positioning System (GPS), Glonass and the future Galileo. GPS has been providing a UTC (Coordinated Universal Time) time distribution service since its inception. This paper will outline present performance of GPS UTC time distribution and show projections for Galileo and the planned modernized GPS UTC distribution performance. This paper will also outline efforts to harmonize the underlying navigation time scales of both GPS and Galileo to better facilitate a combined Navigation solution. A Preliminary Galileo to GPS Time Offset (GGTO) Interface Control Document (ICD) has been drafted and will be outlined as part of this presentation.