slightly ot: DAT clock deviation

[Martin Czech]

The reason for my question was that I'm getting forward with my room
responses. It would be nice to record these severall times and to compute
an average, since this will supress any environmental or other noise. The
problem is that the random noise source I want to use is not correlated
with DAT clock, so each recording may have some fraction of a clock
delay to each other. This will introduce smearing when avereraging.

I don't want to open my portable dat and pull a clock wire out of it...
This would be the best, because the noise source would then be locked
to it.

Maybe I don't need to average at all.  Maybe I can upsample the recording
to 10xFs, then bandlimit to 20kHz and then achieve little delays of 1/10
of the original clock and see which one is the best. But your drift
example shows clearly, that the drift in 100s could well be severall
samples, initial delay could be eliminated, but not drift.

I have an optical out, though. Perhaps I could look at that signal and
restore the clock via pll! Noninvasive.

SPDIF format must be that way, made for restoring a clock out of it,
because no other clock is given.  Has someone tryed this before??


m.c.