differential line
A kind of electrical connection using two wires,
one of which carries the normal signal (V) and the other
carries an inverted version the signal (-V). A differential
amplifier at the reciever subtracts the inverted signal from
the normal signal to yeild a signal proportional to V. This
subtraction is intended to cancel out any noise induced in the
wires, on the assmption that the same level of noise will have
been induced in both wires. {Twisted pair} wiring is often
used to try to ensure that this is the case.
The two wires might be connected at the receiver to separate
{analogue to digital converters} and the subtraction performed
digitally.
The {RS-422} {serial line} {standard} specifies differential
drivers and recievers, whereas the earlier {RS-232} standard
does not.
Opposite: {single ended}.
(1995-03-08)