[time-nuts] Thunderbolt performance in holdover mode

[Mark Sims]

Here is a clean plot of a Thunderbolt in holdover mode.  The graph is 1 hour per major division.  You can clearly see the dependence of the DAC voltage on temperature.  

You can also see that the unit holds the PPS signal within 150 nS for the first eight hours then it starts going wild.  Not shown on the plot is that after 11 hours the PPS signal was off by 1 uS and at 24 hours it was off by 4.5 uS.  The PPS error from 8 to 24 hours was a fairly straight line at 200-250 nS/hour

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