Ordinary medical equipment uses time synchronization to perform functions that were previously performed manually, e.g. recordkeeping and scheduling. These were typically done using watches and clocks, with resultant stability and synchronization errors measured in seconds or longer. The most stringent time synchronization requirements for networked medical equipment derive from some of the security protocols and their record keeping.
Ordinary requirements are:
Synchronized to within approximately 500 milliseconds. Some security systems have problems when the synchronization error exceeds 1 second.
Time base stability
Large drift errors may cause problems. Typical clock drift errors approximately 1 second/day are unlikely to cause problems. Large discontinuities are permissible if rare or during startup. Time may run backwards, but only during rare large discontinuities.
International Time Synchronization
Some sites require synchronization to within a few seconds of UTC. Others have no requirement.