[ntp:questions] how does jitter and round trip time affect the accuracy of the local clock?

David Woolley david at ex.djwhome.demon.invalid
Tue Jun 28 06:52:24 UTC 2011


Miroslav Lichvar wrote:

> 
> In a simulation with 500us exponentionally distributed jitter and
> clock wander insignificant to the PLL time constant, the RMS time
> error is about 40 us for the standard PLL and 80 us for the Linux PLL.
> The 99th percentiles are about 100 us and 200 us respectively.
> 

Significant was a fuzzy term, because I didn't want to do the actual 
maths or simulation, but the key to the real point was your use of the 
word percentile:  with a statistical system, there will not be a hard 
limit on the error.




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