Parallel Flat Wire
o In the past, two parallel flat wires were
used for communication.
o However, EM interference from devices
such as motor can create noise
over
those wires
|
o If
the two wires
are parallel, the
wire closest to
the source of
the noise gets
more
interference and ends up with a higher voltage level than the wire further
away
o This results in an uneven load and a
damaged signal
|
• Noise Effect on Twisted-Pair
o If the two wires are twisted around each
other at regular intervals (b/w 2 &
12
twists per foot), each wire is closer to the noise source for half the time
and
is away for the other half
o Twisting
does not always
eliminate the impact
of Noise but
it does
significantly
reduce it
 |
o With
twisting, therefore the
cumulative effect of
the interference is
equal on
both
wires
o Each section of wire has a
"Load" of 4 when it is on the top of the twist and
'3'
when it is on the bottom
o The total effect of the noise at the
receiver is therefore 0 (14-14)
ƒ Advantage of UTP
 |
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