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Is the unipolar encoding the same as the nrz encoding?


Asked by Olive Thornton on Dec 03, 2021 FAQ



Unipolar has a transition between a zero and positive. The actual measurement can be one of many types of attributes from like voltage, current, pressure, or optical. A bipolar system has a transition between a positive and negative. Any method can employ a bipolar encoding but logically they may be the same as shown with the NRZ example.
Similarly,
NRZ (Non-Return to Zero) - Traditionally, a unipolar scheme was designed as a non-return-to-zero (NRZ) scheme, in which the positive voltage defines bit 1 and the zero voltage defines bit 0. It is called NRZ because the signal does not return to zero at the middle of the bit, as instead happens in other line coding schemes, such as Manchester code.
In fact, Hence in NRZ-Level encoding type, polarity of signal changes when incoming signal changes from 1 to 0 and from 0 to 1. NRZ-L is similar to NRZ except for first data bit. NRZ does not consider 1st data bit as polarity change where as NRZ-L encoding does consider.
Thereof,
Polar encoding • Polar encoding uses two voltage levels (positive and negative). • By using both levels, the average voltage level on the line is reduced & the DC component problem of unipolar encoding is alleviated. • There are three most popular variations of polar coding 1.
Besides,
In NRZ line coding, binary 1 is represented by positive voltage and it does not return to zero during its bit period T0 where as binary 0 is represented by zero voltage. As shown in the figure, in unipolar NRZ, binary '1' is represented by pulse with 'V' amplitude and binary '0' is represented by absence of any pulse.