Balanced and Unbalanced Lines
For a signal to be sent on guided media two wires are needed; one to carry the data and the other to carry the reference.
There are two methods used to do this:
- Unbalanced Transmission
- Balanced Transmission
The two wires in unbalanced lines consist of one for the signal and the other for the reference. The wire used for reference is typically the ground and can be used as a shield against interference, i.e. noise. Unbalanced lines suffer from more problems with noise than balanced. An example of an unbalanced line is coaxial cable.
Balanced lines use both wires to carry data and therefore one is not used for the function of a reference or ground. One wire carries the signal as a positive and the other carries it as a negative. The negative signal is 180 degrees out of phase with the positive; therefore, equal noise occurs on both and can cancel each other. This is known as cancellation and an example of a balanced line is UTP cable.
Click on this link to review the differences between balanced and unbalanced lines.
Next: Unguided Media
