ACRO.IT Acronym Directory

A CCITT line coding technique specified for the fourth-level CCITT multiplex signal. CMI is also used in other applications, notably in Japanese DS1 level systems. CMI is similar to digital biphase coding, in that an abundance of signal transitions exist, and there is no DC energy in the signal. Additionally there is no limit on the number of consecutive zeros allowed in the bit stream. CMI encodes ones (marks) as bipolar NRZ level/AMI; zeros are encoded as a half-cycle square wave of one particular phase.