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Showing posts from September, 2014

UniPolar Encoding

Unipolar encoding has 2 voltage states with one of the states being 0 volts. Since Unipolar line encoding has one of its states being 0 Volts, it is also called Return to Zero (RTZ). A common example of Unipolar line encoding is the logic levels used in computers and digital logic. A logic High (1) is represented by +5V and a logic Low (0) is represented by 0V. Unipolar line encoding works well for inside machines where the signal path is short but is unsuitable for long distances due to the presence of stray capacitance in the transmission medium. On long transmission paths, the constant level shift from 0 volts to 5 volts causes the stray capacitance to charge up. There will be a "stray" capacitor effect between any two conductors that are in close proximity to each other. Parallel running cables or wires are very suspectible to stray capacitance. If there is sufficient capacitance on the line and a sufficient stream of 1s, a DC voltage component will be