M-ary Encoding
he word binary represents two bits. M represents a digit that corresponds to the number of conditions, levels, or combinations possible for a given number of binary variables.
This is the type of digital modulation technique used for data transmission in which instead of one bit, two or more bits are transmitted at a time. As a single signal is used for multiple bit transmission, the channel bandwidth is reduced.
If a digital signal is given under four conditions, such as voltage levels, frequencies, phases, and amplitude, then M = 4.
The number of bits necessary to produce a given number of conditions is expressed mathematically as
