[time-nuts] UBlox as a reference clock source - accuracy ??

[Hal Murray]

softfoot at hotmail.com said:
> I am really interested in the long term accuracy of the 10MHz signal -  say
> over 24 hours. 

What do you mean by "accuracy"?

If all goes well, I expect the 10 MHz will be stable.  It will have spurs and 
look ugly on a scope, but a clock will keep very good time.

Suppose something bad happens, the unit looses lock and drifts off by more 
than a half cycle.  How does it recover when it starts working again?

One option is to forget how many cycles it has drifted and get the frequency 
back to target.  That means the short term frequency will be good, but a clock 
will be off by the number of dropped/picked cycles.

The other approach is to slew the clock to fixup those cycles.  That means the 
frequency will be off in the other direction for a while, but the clock will 
be right after recovery.


-- 
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