Editing Bipolar encoding (section)

[[Image:Ami encoding.svg|thumb|right|360px|[[Leet|1337]] number, as represented in bipolar encoding, known as AMI (Alternate mark inversion), where : {{math|1=''1337''<sub>10</sub> = ''10100111001''<sub>2</sub>}}]]
In telecommunication, '''bipolar encoding''' is a type of [[return-to-zero]] (RZ) [[line code]], where two nonzero values are used, so that the three values are +, −, and zero. Such a signal is called a '''duobinary signal'''. Standard bipolar encodings are designed to be [[DC-balanced]], spending equal amounts of time in the + and − states. 

The reason why bipolar encoding is classified as a [[return to zero]] (RZ) is that when a bipolar encoded channel is idle the line is held at a constant "zero" level, and when it is transmitting bits the line is either in a +V or -V state corresponding to the binary bit being transmitted. Thus, the line always returns to the "zero" level to denote optionally a separation of bits or to denote idleness of the line.