NRZ (non-return-to-zero) refers to a form of digital data transmission in which the binary low and high states, represented by numerals 0 and 1, are transmitted by specific and constant DC (direct-current) voltages. In positive-logic NRZ, the low state is represented by the more negative or less positive voltage, and the high state is represented by the less negative or more positive voltage. Examples are: Logic 0 = +0.5 volts
Logic 1 = +5.0 volts. Logic 0 = -3.0 volts. Logic 1 = 0.0 volts. In negative-logic NRZ, the low state is represented by the more positive or less negative voltage, and the high state is represented by the less positive or more negative voltage. Examples are: Logic 0 = +5.0 volts. Logic 1 = +0.5 volts. Logic 0 = 0.0 volts. Logic 1 = -3.0 volts. Some people wonder why the name of this mode is preceded by"non" when one of the logic states might be represented by zero voltage. The answer becomes apparent from the comparative definition of RZ (return-to-zero)