AMI – Alternate Mark Inversion
The ‘Alternate Mark Inversion’ is a type of bipolar encoding technique where three voltage levels (positive, negative and zero) are used to represent the series of digital bits. In AMI particularly, a no voltage represents a binary 0 bit. Binary 1’s are represented by alternating positive and negative voltages.
The AMI technique is normally used in long distance communication, but it has a problem of “synchronization” with long sequences of 0’s.