[time-nuts] Are cable delays frequency dependent?

Ian Sheffield ian.sheffield1 at tesco.net
Sat Sep 12 18:21:24 UTC 2009

Think of light dispersing through a prism creating a spectrum. The amount of 
bending (which is equivalent to the amount of slowing down of the light) is 
very frequency
dependent there.

----- Original Message ----- 
From: "Hal Murray" <hmurray at megapathdsl.net>
To: <time-nuts at febo.com>
Sent: Saturday, September 12, 2009 5:33 PM
Subject: [time-nuts] Are cable delays frequency dependent?

> 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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