Source variation is a valuable metric within the Timebeat application. This metric allows you to gain confidence in your sources of UTC and the level of synchronisation that Timebeat provides. Source variance is sometimes referred to as Traceability which is important for many reasons, not the least for some timing regulations.
For an enhanced system of Source Variation check out the Squared guide and how Timebeat can dynamically handle multiple sources and verifies their effectiveness in real-time.
It is important to note that you will only log Source Variation metrics if your system is configured to have multiple Primary UTC sources configured (not just traditional BMCA config). If you are using a mix of PTP, PPS, and NTP then this metric will be available but this may not create the optimal configuration for clock sync - the Timebeat support team can assist in enhancing your set up if desired.
Source variance is a metric that starts to be recorded when you have 2 or more active sources of UTC reporting.
The graph depicts multiple sources of UTC in the primary state.
The above image represents 3 active sources of UTC. From the graph, it is easy to see that 2 of the sources agree with each other more than the other (the bottom line on the graph is the outlier).
In simple terms, the source variance is the range between the top line on the graph above and the bottom line.
If we compare the graph above and the graph below we will be able to see that the variance corresponds.
The above graph is the Source Variance value, this represents the maximum difference in the agreement of your sources.
The benefit of understanding this is that it can provide a check and balance of your sources of UTC. Put simply it can very effectively show when you have an errant or deviating source of UTC.
At Timebeat we recommend multiple sources of UTC. As Timebeat synchronises to the median source when using MSSA a single deviating source is protected against as it will not affect synchronisation if there are 3 sources in use.