Polar Encoding

The polar encoding uses the variant voltage levels to represent the binary data. Polar encodings is available in four types:

Polar Non-Return to Zero (Polar NRZ)

It mainly uses two different voltage for the presentataion of data. The positive voltage represents the value 1 and the negative value represents the value 0. t is also NRZ because there is no rest condition.

NRZ scheme has two variants: NRZ-L and NRZ-I.

NRZ-L changes voltage level at when a different bit is encountered whereas NRZ-I changes voltage when a 1 is encountered.

Return to Zero (RZ)

Problem with NRZ is that the receiver cannot conclude when a bit ended and when the next bit is started, in case when sender and receiver’s clock are not synchronized.

RZ uses three voltage levels, positive voltage to represent 1, negative voltage to represent 0 and zero voltage for none. Signals change during bits not between bits.

Manchester

This encoding scheme is a combination of RZ and NRZ-L. Bit time is divided into two halves. It transits in the middle of the bit and changes phase when a different bit is encountered.

Differential Manchester

This encoding scheme is a combination of RZ and NRZ-I. It also transit at the middle of the bit but changes phase only when 1 is encountered.