1/f noise (was: RE: super cables)

[Haible Juergen]

	> 1/f means that the
	>spectral noise power density goes up when frequencys goes to zero,
there
	>seems to be no indication for a limit, the gurus say that the
on-time T
	>of an apparatus sets the limit, because frequencys smaller then 1/T
can
	>not be observed then. Very clever... but makes me feel
uncomfortable...

I've read in some book that the DC offset voltage drift of opamps can be
considered the naturaral extension of 1/f noise. If memory serves, the
intention of this article was to point out the non-deterministic way of DC
offset, and that you cannot really *measure it*, because DC means infinite
time, and that we normally speak of "DC" when we're actually dealing with
step functions in the minutes, hours or days range, in practical life.
I have *no* idea if DC offset voltage drift has actually the same underlying
mechanism as 1/f noise or not, but I admit I like the holistic approach to
this problem.

Anybody knows for sure ?

JH.


PS.: Don't tell me that at DC noise would become infinite. This means
nothing
more or less than *after infinite time* there is maximum entropy in the
world (;->).