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Gussing formula of jitter

Joined
Sep 20, 2018
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#1
Since English is not my first language, hope you can understand.

I think jitter has the simplest formula like this:
jitter=j+f(data,temperature)+factorsA(I don't know)
j is an initial fix value which determined by your audio system.Generally if your system doesn't change ,this value is a constant value.
f is a function, and it has two parameters, one is data, data is the audio data you are playing. And temperature is the temperature inside DAC.

This is just my imagination...
I wish one day we would erase jitter.
 

amirm

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#2
The reason for jitter is usually lack of good design. Vast majority of time it is dealt with effectively though as far as it being audible.

When the design is not good, yes, it is caused by power, data, and maybe temperature and day of the month. :)
 

jsrtheta

Active Member
Joined
May 20, 2018
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#3
Since English is not my first language, hope you can understand.

I think jitter has the simplest formula like this:
jitter=j+f(data,temperature)+factorsA(I don't know)
j is an initial fix value which determined by your audio system.Generally if your system doesn't change ,this value is a constant value.
f is a function, and it has two parameters, one is data, data is the audio data you are playing. And temperature is the temperature inside DAC.

This is just my imagination...
I wish one day we would erase jitter.
Jitter is not really a problem.
 
Joined
Apr 24, 2018
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Location
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#4
I realize this is essentially a joke thread, but if TuneInSoul is serious, or if others dropping by expect a real answer, I thought I'd share a bit.

Jitter is in all designs, good and bad. The jitter can measurably increase with travelling just a couple inches of trace on a PCB. The formula I've always used for evaluating average random power induced by jitter is:

induced S/N = 20 log (signal period / RMS jitter) - 16dB

Where: signal period and RMS jitter are in seconds

Note that the requirements for jitter are completely independent of sample rate, as the desired audio signal itself is what sets jitter requirements. From this equation we can note that an RMS jitter of 10ppm yields a S/N of about -84dB, or about 14 bits of goodness. 10ppm with a desired signal period of 50us (20kHz), is 0.5ns.

BIG CAVEAT: This formula ONLY works with random jitter. Random jitter, in my opinion, is the most benign form of jitter. Random jitter results in random noise. There are two other forms of jitter I feel are much more important than random jitter, cyclical/correlated and cyclical/uncorrelated. Jitter increased via an SPDIF connection is predominately cyclical/correlated, whereas jitter induced by jitter reducing PLLs is dominated by cyclical/uncorrelated.

Yeah, I know, a lot of words but not much value. Welcome to my world.
 
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