BALANCED LINE

In telecommunications and professional audio, a balanced line or balanced signal pair is a transmission line consisting of two conductors of the same type, and equal impedance to ground and other circuits. Balanced lines are often operated with differential signals, one of which is the inverse of the other. External interfering sources, when present, tend to induce a common mode signal on the line.The balanced impedances to ground minimizes interference pickup. The conductors are sometimes twisted together to ensure that each conductor is equally exposed to any external magnetic fields that would induce unwanted noise. The line is capable of being operated in such a way that when the impedances of the two conductors at all transverse planes are equal in magnitude and opposite in polarity with respect to ground, the currents in the two conductors are equal in magnitude and opposite in direction.
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A transmission line consisting of two conductors in the presence of ground, capable of being operated in such a way that when the voltages of the two conductors at all transverse planes are equal in magnitude and opposite in polarity with respect to ground, the currents in the two conductors are equal in magnitude and opposite in direction. (188 ) Note: A balanced line may be operated in an unbalanced condition. Synonym balanced signal pair.