Non-return-to-zero

In <a href="/facts/Telecommunications/vxoj1cxR">telecommunications</a>, a non-return-to-zero (NRZ) <a href="/facts/Line_code/x9IuaYNL">line code</a> is a <a href="/facts/Binary_coding/v5YF0sQl">binary</a> code in which ones are represented by one <a href="/facts/Significant_condition/YlQ3JHVr">significant condition</a>, usually a positive voltage, while zeros are represented by some other significant condition, usually a negative voltage, with no other neutral or rest condition.
For a given <a href="/facts/Data_signaling_rate/MX5a58TH">data signaling rate</a>, i.e., <a href="/facts/Bit_rate/ppUNMmVd">bit rate</a>, the NRZ code requires only half the <a href="/facts/Bandwidth_(signal_processing)/7eMDzfJI">baseband bandwidth</a> required by the <a href="/facts/Manchester_code/0nb5SVmP">Manchester code</a> (the passband bandwidth is the same). The pulses in NRZ have more energy than a <a href="/facts/Return-to-zero/Pq239gv7">return-to-zero</a> (RZ) code, which also has an additional rest state beside the conditions for ones and zeros.
When used to represent data in an <a href="/facts/Asynchronous_communication/sz5DacK8">asynchronous communication</a> scheme, the absence of a neutral state requires other mechanisms for bit synchronization when a separate clock signal is not available. Since NRZ is not inherently a <a href="/facts/Self-clocking_signal/VRaK2817">self-clocking signal</a>, some additional synchronization technique must be used for avoiding <a href="/facts/Bit_slip/LJwnCRn3">bit slips</a>; examples of such techniques are a <a href="/facts/Run-length_limited/WkGWpAGR">run-length-limited</a> constraint and a parallel synchronization signal.

Non-return-to-zero open-in-new

Non-return-to-zero