[time-nuts] Holdover

Mark Sims holrum at hotmail.com
Tue Aug 16 22:49:13 EDT 2016

The Trimble GPSDOs and most of the SCPI ones (like the Z3801A) have "jam sync" commands that force the receiver to do an immediate time sync (the Z3801A requires the device to be in holdover before it will accept a jam sync).  Some also have commands where you an also specify thresholds where the receiver alarms and/or does an automatic jam sync and thresholds for loss-of-signal time before the device goes into holdover mode.


I have selected a somewhat more intricate setup in which you can set a 
re-assignment limit, so when the phase error is outside of that limit, 
you turn the output off, jumps the phase difference, and then starts to 
track in from there. The reason being that at some time deviation, the 
time it takes to track in the phase error is too large to be practical 
so turning of and jump has less impact.

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