M-ary transmission


An M-ary transmission is a type of digital modulation. Instead of sending one bit at a time as in binary, multiple messages, M, are sent. The binary data stream is divided into n tuples, where n = logâ‚‚ M bits. The signals can be represented as different frequencies, as in MFSK. In Mpsk, a data bit is represented by a symbol with a particular initial phase, increasing bandwidth efficiency n times. In M-ary ASK, MAM, signals have the same phase but different amplitudes, and in M-ary PSK, signals have the same amplitude but different phases. QAM uses both amplitude and phase modulations.[1]

This type of transmission results in reduced channel bandwidth. However, sometimes, two or more quadrature carriers are used for modulation. This process is known as quadrature modulation.

References

  1. ^ Xiong, Fuqin (2000). Digital Modulation Techniques. Norwood: Artech House. pp. 13, 102, 136, 411, 422. ISBN 9780890069707.


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