[time-nuts] wander and jitter measurements

bill billj9 at citlink.net
Fri Jun 27 13:37:27 EDT 2014


On 6/26/2014 2:39 AM, mike cook wrote:
> A few dumb questions:
>
> But first a quote from the ITU ( doc G.180 )
>
> ""4.1.12 (timing) jitter: The short-term variations of the significant instants of a timing signal from
> their ideal positions in time (where short-term implies that these variations are of frequency greater
> than or equal to 10 Hz).
>
DQ1 yes

DQ2 Frequency offset would come into the Wander category except it 
defined differently.

DQ3 No


That gives my take on your q questions. Its been 23 years since I had 
think about jitter and wander as chairman of T1X1.3 committee

Bill
K7NOM
> 4.1.15 wander: The long-term variations of the significant instants of a digital signal from their
> ideal position in time (where long-term implies that these variations are of frequency less than
> 10 Hz).
> NOTE – For the purposes of this Recommendation and related Recommendations, this definition does
> not include wander caused by frequency offsets and drifts.""
>
> DQ1. These both refer to phase variations, so with the exception of the frequency range specified, are they mathematically equivalent?
>
> DQ2.  The note on wander excludes frequency offsets, but that is not specified for jitter, so do I have to include a frequency offset in jitter measurements? It seems to me that it make no sense to do so.
>
> DQ3.  Can I deduce an underlying frequency offset from jitter (wander) by  taking an RMS value over some window of values?
>
>
> regards,
> Mike
>
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