Encoding schemes: Polar Schemes

􀂄Polar encoding schemes rely on the voltage level to make a determination of whether a binary 1 or a 0 was sent.
􀂄Common Schemes:
􀁺UnipolarNRZ:binary 1: +A volts, binary 0: 0 volts.
􀁺Polar NRZ:binary 1: +A/2 volts, binary 0: –A/2 volts.
􀃎Half the power requirement of unipolarNRZ
􀁺Bipolar:Consecutive binary 1s: +/-A/2 volts, binary 0: 0 volts
􀃎Produces a frequency spectrum with less low frequency components.
􀂄Drawbacks to polar encoding schemes are:
􀁺Long strings of either 1s or 0s can cause loss of timing information
􀁺Systematic errors in polarity can cause all 1s to be read as 0s and vice versa