Coded mark inversion

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CMI line coding
CMI line coding

In telecommunication, coded mark inversion (CMI) is a non-return-to-zero (NRZ) line code. It encodes zero bits as zero-to-one transitions at the pulse's center and one bits as a constant level for the entire pulse time. The one's constant level is inverted each pulse.

CMI doubles the bitstream frequency, when compared to its simple NRZ equivalent, but allows easy and reliable clock recovery.

[edit] References

  • ITU-T G.703 (11/2001), Annex A, A.3 Definition of CMI.

[edit] See also

Manchester code

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