Non return to zero, inverted（简称：NRZI）中文译为：翻转不归零制，是二进制信号，此信号对应于实体性发送（transmission），以此欲于一些发送媒体（介质）。

NRZI的发送信号有两种准位，并且在准位信号内也已经夹带了同步时脉信号于内，电位保持时发送逻辑1，电位翻转时发送逻辑0。

目前为止，使用NRZI编码法的应用有CD光盘、USB接口、以及使用光纤传输的100BASE-FX（Fast Ethernet）等。

举例而言，想像一个数据串流包含的比特依序为"10110010"，假设初始状态为“H”（一个高的信号电平）。这个比特流就会通过NRZI编码转化成"LLHLLLHH"，在这里，“L”对应于一个低的信号电平，而“H”对应于一个高的信号电平。类似地，如果初始状态为“L”，那幺这个比特流就会被编码成"HHLHHHLL".

In telecommunication, a non-return-to-zero (NRZ) line code is a binary code in which ones are represented by one significant condition, usually a positive voltage, while zeros are represented by some other significant condition, usually a negative voltage, with no other neutral or rest condition. The pulses in NRZ have more energy than a return-to-zero (RZ) code, which also has an additional rest state beside the conditions for ones and zeros. NRZ is not inherently a self-clocking signal, so some additional synchronization technique must be used for avoiding bit slips; examples of such techniques are a run length limited constraint and a parallel synchronization signal.