The frequency holdover or partial holdover function is an example of how frequency references could be used in phase & time synchronization. This Net.Time feature provides nanosecond accuracy for a long time when GNSS or PTP references are lost.

The accuracy of a watch depends on the application. Anyone who wants to catch a train has to have an eye on the minutes. In competitive sport, a hundredth of a second can be decisive and a packaging machine may need microsecond accuracy.