Answer Explanation:
NRZ (NON RETURN TO ZERO) : In NRZ encoding the level of signal is always positive or negative it is never zero the two useful method of NRZ transmission are NRZ-L and NRZ-I
NRZ-L: in NRZ-L encoding the level of signal reflects the representation of the bit . in this encoding the positive voltage is represented as 0 and negative voltage is represented as 1
NRZ-I : in NRZ-I encoding an inversion of voltage level is represented as 1 bit it is the transition between the positive and negative voltage not the voltages themselves.
NOTE : NRZ-I is superior to NRZ-L because NRZ-I synchronize the signal
