Synchronized UTC for distributed real-time systems

We present a novel technique for establishing a highly accurate global time in fault-tolerant, large-scale distributed real-time systems. Unlike the usual clock synchronization approaches, our clock validation technique provides a precise system time that also relates to an external time standard like UTC with high accuracy. The underlying idea is to validate time information of external time sources like GPS-receivers against a global time maintained by the local clocks in the system. As an example, a promising interval-based clock validation algorithm ICV that exhibits excellent fault-tolerance properties is outlined and analyzed. It requires only a few high-accurate external time sources and provides each node with the actual accuracy of its clock.