[time-nuts] Phase noise confusion II

[Bob kb8tq]

Hi

Which of the multitude of definitions are we talking about? 

One very common definition looks at peak to peak jitter and does
not care about the center. Another looks at +/- peak to edge and 
then uses the greater of the two numbers. Other definitions look
at RMS jitter and generally don’t care about the edge. 

At least to me, the biggest problem is that any time “peak” or “peak 
to peak” comes in to a calculation that involves random noise, 
things go sideways fast. People pretty much never want to 
define a confidence level (how any sigma?). They want an 
absolute number. 

Lots of fun

Bob

> On Apr 10, 2020, at 6:05 AM, Dana Whitlow <k8yumdoober at gmail.com> wrote:
> 
> Question about definition of jitter:   Is it the variation in
> pulse-to-pulse spacing, or is it
> the variation in pulse positions with respect to a jitter-free waveform?
> 
> Dana
> 
> 
> On Thu, Apr 9, 2020 at 11:21 PM Hal Murray <hmurray at megapathdsl.net> wrote:
> 
>> 
>> richard at karlquist.com said:
>>> There is always an implied clock recovery loop that the the jitter is
>>> measured against. The loop may itself affect the jitter measurement
>> either by
>>> cleaning up jitter or contributing to it.
>> 
>> Interesting.  I hadn't thought about it that way.
>> 
>> Suppose I measure the edge to edge times and make a histogram.  Can I get
>> jitter out of that?  Where is the clock recovery loop?
>> 
>> --
>> These are my opinions.  I hate spam.
>> 
>> 
>> 
>> 
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