An ''M''-ary transmission is a type of

digital modulation Signal modulation is the process of varying one or more properties of a periodic waveform in electronics and telecommunication for the purpose of transmitting information. The process encodes information in form of the modulation or message ...

where instead of transmitting one

bit The bit is the most basic unit of information in computing and digital communication. The name is a portmanteau of binary digit. The bit represents a logical state with one of two possible values. These values are most commonly represented as ...

at a time, two or more bits are transmitted simultaneously. This type of transmission results in reduced channel

bandwidth Bandwidth commonly refers to: * Bandwidth (signal processing) or ''analog bandwidth'', ''frequency bandwidth'', or ''radio bandwidth'', a measure of the width of a frequency range * Bandwidth (computing), the rate of data transfer, bit rate or thr ...

. However, sometimes, two or more quadrature carriers are used for modulation. This process is known as

quadrature modulation Quadrature may refer to: Mathematics * Quadrature (geometry), drawing a square with the same area as a given plane figure (''squaring'') or computing that area ** Quadrature of the circle ** ''Quadrature of the Parabola'' ** Quadrature of the ...

References

An ''M''-ary Transmission Scheme for Chaotic Communications, Kai Y. Cheong, Francis C. M. Lau and Chi K. Tse.
Quantized radio modulation modes Data transmission {{radio-comm-stub