Timing & Synchronization
Precise Time and Synchronisation (Timing&Sync) is crucial to strategic activities, especially for Critical Infrastructure (CI). CI is a system or asset essential for maintaining such vital societal functions as health, safety, security, economic and social well-being of people. GNSS is used to provide this Timing & Sync service in CI.
GNSS can be used to provide both Timing & Synchronisation:
- Timing: GNSS provides direct and accurate access to Coordinated Universal Time (UTC).
- Synchronisation: Synchronisation between receivers at different locations can be established and maintained using GNSS reference time. In addition, a master clock synchronises itself using the time provided by GNSS, redistributing this time to slave clocks disseminated within the systems.
Key stakeholders in Timing&Sync are telecommunication network operators, associations like ENTSO-E in Energy, and regulatory bodies (these are highly regulated markets). Still, needs related to Timing&Sync depend heavily on the application. Accuracy requirements start low in finance transactions (order of milliseconds), are medium-sized in Energy and most Telecom applications (order of microseconds), and are high in Satcom services (order of nanoseconds). There is an increasing interest in GNSS authentication and improved robustness to interference. In Energy, independence and continuity of service are also increasingly valuable. This is part of a global trend of continuous security improvement.
The role of GNSS in Timing and Synchronisation applications
- In Satellite Communication (SATCOM), GNSS is used for TDMA (Time Division Multiple Access) timing on satellite links, terrestrial links and NTP (Network Time Protocol) type services for IT/network/satellite monitoring/control.
- In Professional Mobile Radio (PMR) and Cellular Networks (Cellular), GNSS is used for the synchronisation of timeslots and for handovers between base stations.
- In Public Switched Telephone Networks (PSTN), GNSS is used as a backup in case timing information from atomic clocks is lost. GNSS reference time can be used for time of day, traffic timing and time slot management. Many telecom networks employ local oscillators who enable service to be temporarily maintained in case of GNSS loss.