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Reply With QuoteAre you looking for something more detailed or specific than the Wiki article?
What is clock jitter? What is clock jitter in detail?
Hybrid Mixing and Mastering
Are you looking for something more detailed or specific than the Wiki article?
Alto Dog Studios, Blacksburg, VA
Yep. Despite Wikipedia's notorious reputation for inaccuracies, that article pretty much delineates anything the novice would ever want to know (and a lot more) about clock jitter.
Thankfully, AD/DA has come a long, long way since the days when jitter was a serious enough issue that everyone was using outboard clocks.
Sonic Eclipse Studios
Lynchburg, VA
The Wiki article is detailed but general. In the field of recording, all one usually needs to know is that clock jitter is the variation in time of a sampling instant about the ideal time, and apples to signal conversion between analogue and digital domains in both directions, i.e. both A-D and D-A conversion. Since the analogue waveform is constantly changing, a variation in time translates to a variation in amplitude, and hence an error in the converted signal. This will show as non-harmonic distortion.
I think that (well deserved) reputation comes from pop culture, history, politics, and the "soft" sciences. I find Wiki to be as reliable as any other general reference source that I know of in math and classical physics. Compare it to a modern Encyclopedia Britannica. Wiki is also more comprehensive and the price is right. As always, check it twice. In the word of Ronald Regan, "Trust, but verify." (Which means, "Don't trust.")Originally Posted by Scott Griffin
As someone who moonlights in the medical field, I can assure you, Wiki blows it in that department regularly.
I certainly agree with Boswell's comments but I do have something to add. In just about all spec sheets for audio interfaces jitter is quoted as error between consecutive clock edges rather than the more key aspect, as Boswell infers, of errors in absolute time. Nor have I seen any figures given for clock jitter when externally referenced. Phase noise (particularly in PLL's) when clocks are slaved can be very poor and often do not follow the WIKI suggestion of Guassian noise. This is one of the areas where I certainly think improvements can be made and I think will only happen if we can get better specification of jitter from the manufacturers. Indeed, what is mostly quoted as jitter, to my mind at least, is not a true measure of jitter.
OK this is the tech talk forum, so my question is how far do we want to go into this topic?
This forum could use a topic like the legendary 96K argument on George Massenburg's old (now defunct) forum on Musicplayer....
Go as deep as you like, and offer as provocative an opinion as you dare! *grin*
Maybe the moderators should decide that! :<) I have no intention of being provocative though on a what is a "tech talk" forum and my thoughts have nothing at all to do with anything like a sample rate "sound" debate. Boswell (our revered mod!) has already indicated that the WIKI definition is very general and I am quite sure knows exactly what I have suggested.
Last edited by MrEase; 04-19-2010 at 04:01 PM.
Take all the fun out of it, then. :P
In all seriousness, I'd be intrigued to hear your dissertation and, more specifically, how you believe it affects us these days, post the rise of multi-bit error correction, inexpensive-to-produce mag shielding, oversampling, and other formerly renegade ideas that have become industry standard cures for the jitter bug (pardon the pun).
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