NonReturntoZero
Non-Return-to-Zero (NRZ) is a binary line encoding used in digital communications in which information is represented by two distinct voltage levels and there is no return to a baseline level between successive bits. In NRZ, a 1 and a 0 are encoded by different levels; in its common variants, NRZ-L maps bit values directly to levels, while NRZ-I uses transitions to signal a 1, with a 0 defined as no transition.
NRZ-L (NRZ-Level) encodes each bit by a constant level for the duration of the bit interval. For
NRZ-I (NRZ-Inverted or NRZI) encodes a 1 as a transition and a 0 as no transition. The
NRZ encodings are often contrasted with schemes that guarantee transitions or synchronization per bit, such as