Re: 2 questions...

[Nigel Orr <nigel.orr@xxxxxxx>]

At 21:25 12/08/99 +0100, you wrote:
>A telephone line is essentially a balanced circuit and should be
relatively
>immune to picking up noise, where noise is particularly noticable it is
>usually a sign of a fault on the line.

Agreed, but the 'balancing' concept breaks down when the 2 wires in a pair
are _not_ colinear, ie when the interference source is 'close'.  I would
have thought that adjacent pairs of cat-5, with 100V odd ringing signals
would be close enough to interfere with a couple of volts of signal, though
I suppose it only needs 40-50dB to reject it... and as 'real' phone lines
run in overall screened multipairs for miles without noticeable problems
it's probably fine
;-)

Thanks for the info.

Nigel
--
Nigel Orr                  Research Associate   O   ______
Underwater Acoustics Group,              o / o    \_/(
Dept of Electrical and Electronic Engineering     (_   <   _ (
University of Newcastle Upon Tyne             \______/ \(

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