[time-nuts] Oh dear
jfor at quikus.com
Mon May 7 16:48:39 UTC 2012
Suppose you have a perfect, ideal clock that puts out 'convert' pulses at
an exact rate is used to strobe a high precision A/D.
Now suppose you add jitter to that perfect clock so that the rate stays
the same but time interval between successive pulses varies randomly
between P(1-x) and P(1+x).
How big would x have to be before anyone could detect any difference in
I have my opinion, but what is yours and why?
> On Mon, 7 May 2012 10:02:25 -0600
> Tom Knox <actast at hotmail.com> wrote:
>> Actually the numbers are quite real, play with the math, a small amount
>> of jitter in a DAC (X) can have a large difference (Y) when sampling a
>> complex wave form especially in the audiophile world where the sound of
>> 24bit dac 16,777,216 discrete levels is clearly superior to older
>> 16 bit dac 65,536 possible levels in 44.1 KHz to 192 KHz formats.
> Yes, i know that jitter is a pain when it comes to ADCs, but keep
> in mind that your audio ADC does have a jitter of a couple
> 100ps itself. If it's a high end ADC that is. The standard ADCs are
> in the ns range. For a normal 10MHz XO you measure the jitter in in the
> 10ps at most, a good one at lower than 1ps cycle-to-cycle. Of course, you
> to keep the clock signal clean of any disturbance that might add
> to it. But that's a matter of keeping the power supply clean and having
> signal shielded. It's not an inherent property of an Rb to have low
> And as we all know from the recent hype on the FE-5860As and the
> following measurements, not all Rb's are low jitter.
> Attila Kinali
> Why does it take years to find the answers to
> the questions one should have asked long ago?
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