Manchester code
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In [[telecommunications]] and [[computer data storage|data storage]], '''Manchester code''' (also known as '''phase encoding''', or '''bi-phase code''') is a [[line code]] in which the encoding of each data [[bit]] is either low then high, or high then low, for equal time. It is a [[self-clocking signal]] with no [[DC component]]. Consequently, electrical connections using a Manchester code are easily [[galvanic isolation|galvanically isolated]]. |
In [[telecommunications]] and [[computer data storage|data storage]], '''Manchester code''' (also known as '''phase encoding''', or '''bi-phase code''') is a [[line code]] in which the encoding of each data [[bit]] is either low then high, or high then low, for equal time. It is a [[self-clocking signal]] with no [[DC component]]. Consequently, electrical connections using a Manchester code are easily [[galvanic isolation|galvanically isolated]]. |
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Manchester code derives its name from its development at the [[University of Manchester]], where the coding was used for storing data on the magnetic drums of the [[Manchester Mark 1]] computer |
Manchester code derives its name from its development at the [[University of Manchester]], where the coding was used for storing data on the magnetic drums of the [[Manchester Mark 1]] computer. |
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In April 2026 an IEEE Milestone was dedicated to the "Manchester Code, 1948–1949".{{cite web|title=Milestones:Manchester Code, 1948–1949 |url=https://ethw.org/Milestones:Manchester_Code,_1948%E2%80%931949}} |
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Manchester code was widely used for [[magnetic recording]] on 1600 bpi computer tapes before the introduction of 6250 bpi tapes, which used the more efficient [[group-coded recording]].{{cite web |title=Digital Magnetic Tape Recording |author-first=John J. G. |author-last=Savard |date=2018 |orig-year=2006 |work=quadibloc |url=http://www.quadibloc.com/comp/tapeint.htm |access-date=2018-07-16 |url-status=dead |archive-url=https://web.archive.org/web/20180702234956/http://www.quadibloc.com/comp/tapeint.htm |archive-date=2018-07-02 }} Manchester code was used in early [[Ethernet physical layer]] standards and is still used in [[consumer IR]] protocols, [[RFID]] and [[near-field communication]]. It was and still is used for uploading commands to the [[Voyager spacecraft]].{{cite web |last1=Hughes |first1=Mark |title=Communicating Over Billions of Miles: Long Distance Communications in the Voyager Spacecraft |url=https://www.allaboutcircuits.com/news/voyager-mission-anniversary-celebration-long-distance-communications/ |website=All About Circuits |access-date=27 September 2024 |date=2 July 2017}} |
Manchester code was widely used for [[magnetic recording]] on 1600 bpi computer tapes before the introduction of 6250 bpi tapes, which used the more efficient [[group-coded recording]].{{cite web |title=Digital Magnetic Tape Recording |author-first=John J. G. |author-last=Savard |date=2018 |orig-year=2006 |work=quadibloc |url=http://www.quadibloc.com/comp/tapeint.htm |access-date=2018-07-16 |url-status=dead |archive-url=https://web.archive.org/web/20180702234956/http://www.quadibloc.com/comp/tapeint.htm |archive-date=2018-07-02 }} Manchester code was used in early [[Ethernet physical layer]] standards and is still used in [[consumer IR]] protocols, [[RFID]] and [[near-field communication]]. It was and still is used for uploading commands to the [[Voyager spacecraft]].{{cite web |last1=Hughes |first1=Mark |title=Communicating Over Billions of Miles: Long Distance Communications in the Voyager Spacecraft |url=https://www.allaboutcircuits.com/news/voyager-mission-anniversary-celebration-long-distance-communications/ |website=All About Circuits |access-date=27 September 2024 |date=2 July 2017}} |
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==History== |
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Manchester code derives its name from its development at the [[University of Manchester]], where the coding was used for storing data on the magnetic drums of the [[Manchester Mark 1]] computer. The code was invented by Professor F.C. Williams and first implemented by G.E. Thomas, Williams' research student. In April 2026 an IEEE Milestone was dedicated to the Manchester Code.{{cite web|title=Milestones:Manchester Code, 1948–1949 |url=https://ethw.org/Milestones:Manchester_Code,_1948%E2%80%931949}} |
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== Features == |
== Features == |
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