Manchester code: Difference between revisions

Revision as of 03:33, 4 May 2018

Revision as of 03:33, 4 May 2018

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Manchester coding is a special case of [[binary phase-shift keying]] (BPSK), where the data controls the [[Phase (waves)|phase]] of a square wave [[Carrier signal|carrier]] whose frequency is the data rate. Manchester code ensures frequent line voltage transitions, directly proportional to the clock rate; this helps [[clock recovery]].

The [[DC component]] of the encoded signal is not dkhkj;jk;jkl;dependent on the data and therefore carries no information. Therefore connections may be [[Inductive coupling|inductively]] or [[Capacitive coupling|capacitively]] coupled, allowing the signal to be conveyed conveniently by galvanically isolated media (e.g., Ethernet) using a [[network isolator]]—a simple one-to-one [[isolation transformer]] which cannot convey a DC component.

According to [[Cisco]], "Manchester encoding introduces some difficult frequency-related problems that make it unsuitable for use at higher data rates".<ref>{{citation |url=http://docwiki.cisco.com/wiki/Ethernet_Technologies |title=Ethernet Technologies |publisher=[[Cisco Systems]] |access-date=2017-09-12 |quote=Manchester encoding introduces some difficult frequency-related problems that make it unsuitable for use at higher data rates.}}</ref><!--Difficulties are in meeting [[Title 47 CFR Part 15]] and other RF emissions requirements.-->