[time-nuts] Clocks for Audio gear
Dan Kemppainen
dan at irtelemetrics.com
Thu May 10 19:58:30 UTC 2012
One interesting note however. Years ago we had a standard old 4040
ripple counter in our shop that displayed a low occurrence of jitter
of several times it's input frequency period at it's lowest frequency
output (Sort of what you are describing below). I wish I had the
numbers handy, but the output would be good for most of the time, then
every once in a while it would jump to a longer delay. It was hard to
catch with a scope, but when we measured every single pulse width it
showed up fairly well. The high speed clock (A TTL OSC in a can) never
skipped, as far as we know.
We never did figure that one out. From what I remember we switched IC
manufacturers, and the problem when away.
Dan
On 5/10/2012 1:49 PM, time-nuts-request at febo.com wrote:
> A TTL can that is marked "4.096 MHz" costs about $2 and will make a
> square wave with a period of very close to 250 nS. Then they divide
> this down to the sample rate of 96KHz. In order to see a 250 nS
> jitter in the 96K signal the TTL can would have to "skip a beat".
> 250 nS is is a huge error and you don't get there with digital noise
>
> Chris Albertson
> Redondo Beach, California
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