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.

In figuring, AMI (Substitute Imprint Reversal) is a coordinated clock encoding strategy which utilizes bipolar heartbeats to address coherent 1 qualities. It is hence a three-level framework. A legitimate 0 is addressed by no image, and a sensible 1 by beats of rotating extremity. The rotating coding forestalls the development of a d.c. voltage in the link. This is viewed as a benefit since the link might be utilized to convey a little d.c. current to control middle of the road hardware, for example, line repeaters.AMI coding was utilized widely in original PCM organizations, yet experiences the downside that a long run of 0's delivers no changes in the information stream (and in this way doesn't contain adequate changes to ensure lock of a DPLL). Effective transmission consequently depends on the client not wishing to send long runs of 0's and this sort of encoding isn't hence straightforward to the arrangement of pieces being sent.The HDB3 encoding plan is one of numerous which have been created to give customary changes independent of the example of information being conveyed.