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[[File:Manchester encoding both conventions.svg|thumb|right|400px|An example of Manchester encoding showing both conventions]]
The '''Manchester code''' is a [[Binary code|binary encoding]] which also encodes the [[clock signal]]. This is very useful, because an external clock signal is no longer needed. A sequence of bits [[Modulation|modulates]]{{Disambiguation needed|date=February 2022}} the [[Phase (waves)|phase]] of the signal. This is a form of [[Phase shift key]]ing, often shortened to PSK.

Otherwise put, the information about the signal is in its signal flanks, that is when the signal changes.

Manchester codes are widely used, for example for [[Ethernet]] or for [[RFID]].

== Representation ==
There are two ways to represent a Manchester code:
# A falling signal flank represents a logical ''1'' and ascending flank is a logical ''0''. This is the original definition given by [[G.E. Thomas]]
# A falling signal flank is a logical ''0'', the ascending one a logical ''1''. This is the definition used by the original [[Ethernet]] standard.

To rule out ambiguities, Manchester codes use a ''preamble''. A preamble is a fixed sequence that is known beforehand.

== Advantages and disadvantages ==
One of the advantages of Manchester code is that the [[DC bias|DC component]] of the signal carries no information. This makes it possible that standards that usually do not carry power can transmit this information. One of the drawbacks of the encoding is that it needs more [[Bandwidth (signal processing)|bandwidth]] than other encodings, such as [[Non-return-to-zero|NRZ]].


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[[Category:Telecommunications]]
[[Category:Encodings]]