On Mon, 05 Jul 2004 03:46:09 GMT, Monte McGuire
wrote:

In article ,
"Phil Allison" wrote:

This sort of interference is reduced by the fact the two wires are
*twisted* inside the cable which reverses the phase of any hum signal picked
up every inch or so along the line and hence cancels it out. Where multiple
twisted pairs are used in the same cable the twisting reduces crosstalk in
the same way as above.

Yes, twisting makes the loop area effectively zero, so there's no mutual
coupling and thus no induced current and thus no induced voltage.

Imagine the simpler case of a balanced signal on an untwisted pair
line. What is now different in the induced current? First consider
the case of the two conductors having *no* spacing. Then the case of
spacing significant compared to a wavelength.

Next consider the case of the same lines with a single twist centered
on a symmetrical hum source. Then with infinite twisting.

All this talk about "reversing the phase" etc. is fundamentally
flawed, IMO.

Chris Hornbeck