Timebeat Offset readings provide up to date, real-time measurements for how accurate your clocks are to your Source input (traditionally this would be UTC).
We recommend that you focus on looking at the EMA values if using software timestamping as this provides the simplest human-readable long term averages of your sync status. For Hardware timestamping in general Timebeat outperforms all other PTP stacks so you can use the RAW values as a reference due to the long term average being remarkably close to 0-1ns.
As the System clock (software timestamping), is remarkably less accurate than hardware timestamping the EMA can give you a better read of your sync performance in real-time.
EMA and Raw Offset:
Light blue line shows the EMA, purple dots are the RAW, note the averages in the legend bottom right. This is from Hardware timestamping.
Timebeat reports its offset data using 2 primary field definitions Raw and EMA. EMA is traditionally the value that is used for quick reference to the offset as this is easily digestible and provides a simple, stable reading for use in reports and visualisations.
The Raw values are also plotted on the graphs and will appear around the EMA line as dots this provides a useful representation of the spread of your sync (the smaller the better).
EMA: is the exponentially weighted average of the offset of the clock from the source UTC
Raw: is the offset of the clock from the PTP packets being received (UTC) in its unedited form, I.e. no averages or smoothing takes place.
The Raw field is useful for understanding the spread of your UTC source to clock error, it is the goal of Timebeat to reduce this spread as much as possible.
Understanding the nuances of time representation can start to get confusing when looking at the Raw offset which is why we tend to recommend looking at the EMA for a quick glance at your sync state.
The Raw offset looks like your clock is jumping around a large amount but in reality, you should think of it as the difference between your clock and the PTP message stated offset. This doesn't mean the clock in question is jumping around but typically that the PTP message transfer is not a constant. This being said you still want to see the Raw value as small as possible as this lowers the margin of potential error that can be introduced by various "unknowns".
For more detailed explanations into the minutia of what Raw represents and why EMA is a more useful day to day value, you can get in touch with one of the Timebeat team.