[time-nuts] time-nuts Digest, Vol 117, Issue 61
Tom Van Baak
tvb at LeapSecond.com
Fri Apr 18 18:45:35 EDT 2014
Remember also that electrons do not read law or speak english -- so they know nothing about the arbitrary words used to qualify wow & flutter, jitter & wander, signal & noise, or short- & long-term stability.
They do, however, respect mathematics. And so when you make a frequency domain plot (e.g., L(f) phase noise) or time domain plot (e.g., Sigma(tau) Allan deviation) the results are a seamless report of performance from as small to as large as you can measure.
BTW, how will you test and validate that your phase noise measurement device is giving correct results?
----- Original Message -----
From: "Bob Camp" <lists at rtty.us>
To: "Discussion of precise time and frequency measurement" <time-nuts at febo.com>
Sent: Friday, April 18, 2014 7:12 AM
Subject: Re: [time-nuts] time-nuts Digest, Vol 117, Issue 61
The dividing line between wander and jitter is a “legal" one rather than a physics one. It’s a breakpoint in a spec where the treatment of the noise changes from “do this” to “do that”. In most cases you pass wander and you attenuate jitter. Different specs put the line at different points based on hoped for system performance.
On Apr 18, 2014, at 9:17 AM, HagaaarTheHorrible <hagaaar587plus7 at googlemail.com> wrote:
> Hi Dave and thanks for the quick answer!
> My thesis is about a phase noise measurement device I developed, which primary use is to measure phase noise/jitter of audioband DACs. I probably won't be focussing on jitter too much but would like to know if there even is one accepted standard definition.
> For example, in the different definitions I found so far, the seperation between jitter and wander sometimes is given to be at 1Hz, 10Hz and sometimes just mushy definitions like "very low frequencies"...
> I doubt it is that important for my thesis anyway, but I'd really like to know for myself, so if anyone has a pointer for me it would be greatly appreciated!
>> Von: "Dave Brown" <tractorb at ihug.co.nz>
>> Datum: 17. April 2014 11:21:25 MESZ
>> An: "Discussion of precise time and frequency measurement" <time-nuts at febo.com>
>> Betreff: Re: [time-nuts] Jitter Definition
>> Antwort an: Discussion of precise time and frequency measurement <time-nuts at febo.com>
>> It depends on what your thesis is all about- you could try some of the ITU documents for 'official' definitions but these may or may not be relevant to your thesis.
>> DaveB, NZ
>> ----- Original Message ----- From: "HagaaarTheHorrible" <hagaaar587plus7 at googlemail.com>
>> To: <time-nuts at febo.com>
>> Sent: Thursday, April 17, 2014 2:54 PM
>> Subject: [time-nuts] Jitter Definition
>>> Hello there,
>>> I tried searching the archives (and google, IEEE, NIST, ITU), but didn't really find a satisfying answer, so I thought I'd ask directly.
>>> In short:
>>> Is there any kind of standard definition for Jitter which is commonly accepted?
>>> I (think I) understood Jitter and phase noise by now, yet I need to give some references in my bachelor's thesis, so I'm looking for a definition. So far I haven't found a real definition of the different "types" (RMS,p2p,c2c,...) and components(RJ,DJ) of Jitter, but I guess there must be some kind of accepted standard!?
>>> If anyone could point me to some "official sources" which are "accepted in the industry", I'd be very grateful.
>>> Thanks in advance and best regards
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