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Jeff McAdams wrote:
Actually, DSL and voice audio are not balanced signals, they each use a
single transmit and single receive signal. Balanced being, that there
are two transmit signals and two receive signals, each with the same
signal, but with opposite polarity from each other. So, you have a
positive tx and a negative tx, and they are sent on pins that twist
around each other (thus the name "twisted pair"). The signal is
measured at the far end as the difference between the two pins, rather
than the signal on a pin from ground. So, if you get an induced current
in a non-balanced signal, it will change the signal as received on the
far end (because the voltage relative to ground has changed). If you
get an induced current in a balanced signal, it will (in theory, at
least) induce the current in both wires equally, with the result that
the difference in voltage between the two wires will remain the same, so
the signal as determined by the far end remains the same.
Nice explanation. Now I have an image of an op-amp in my head! (That
also helps to explain balanced microphones.)
One time I tried Cat3 to see if I could get a better modem connection.
It didn't help.
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