Galileo's timekeeping infrastructure: where do we go with the external time service provider?

This paper summarize the Galileo timekeeping infrastructure. The purpose of such infrastructure is to: generate a stable time scale (Galileo system time, GST) to fulfil the needs of the core services (i.e. open service, safety-of-life service etc.), provide UTC parameters for broadcast, determine the GPS to Galileo time offset (GGTO) in order to facilitate the user's interoperability. A description of the different time related actors and their corresponding roles within and outside the Galileo core infrastructure was given in (R. Hlavac et al., 2006). The main elements are the precise timing facility (PTF) being part of the Galileo ground mission segment (GMS), the external time service provider (TSP) and the external GPS system for the provision of GPS to Galileo Time Offset. The core function of the PTF is to generate GST, including a physical realization, GST Master Clock (GST(MC)), for metrological purposes and for providing timing reference signals to all elements within the Galileo system. The main task of the TSP is to provide the GST to UTC mod 1 sec steering corrections, and the offset between GST and UTC as required for the provision of the UTC time dissemination In this paper we will emphasize the evolution of the time service provider prototype facility (GTSPF) currently under development towards a permanent time service provider facility and entity for the fully operational system. This opens up many questions in the technical, legal, institutional, and marketing areas: ldr How can the TSP -once in operation -improve its products? ldr How do we see the cooperation of the National Metrology Institutes in the future and how do they contribute to the success of the time service provider products? ldr Having the operational Galileo system as one important customer of the TSP (which stipulated its development) are there other potential customers? ldr Is there an interest for a certified time service? ldr Is there a requirement to establish an EU legal time and can the TSP contribute to that? This paper aims at stimulating discussion among interested parties; it cannot at this stage provide conclusions and solutions.