Hi
A lot depends on the structure of the cable it's self. For plastic
dielectric cables the answer is normally "yes the delay is frequency
dependent".
One mechanism is simply that the velocity of propagation it's self is
frequency dependent in the material used. Some of the mechanism's are
pretty crazy. Periodic spacers in air / plastic cables can give some
very odd frequency dependent reflections. Even without something odd
like periodic spacers, the cable's characteristic impedance varies
with frequency. With constant termination impedances, you have a
mismatch. Again, you get reflections that are frequency dependent.
Bob
On Sep 12, 2009, at 12:33 PM, Hal Murray wrote:
If so, what's the mechanism?
I know that attenuation is frequency dependent due to skin effect
but I can't
turn that into variable delays. Is there a magic term I should
google for
and/or does anybody have a good URL?
Context is a memory from 20 years ago. I think it was a data sheet
or app
note for clock recovery on a T1 line. Maybe it was just explaining
the specs
for a line amplifier. The idea was that the recovered clock would
shift
depending on the frequency of the signal. The frequency depended on
the data
pattern so you could harass the clock recovery by picking nasty data
patterns.
I think I almost understood it back then when I had the info in
front of me.
I've tried to remember or reconstruct it a couple of times over the
years,
but I've never been successful.
--
These are my opinions, not necessarily my employer's. I hate spam.
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