Multiplexing

Multiplexing is a method by which many parameters are tested and processed simultaneously.

Multiplexing (also muxing or MUXing) in telecommunications is the combining of two or more information channels onto a common transmission medium using hardware called a multiplexer or (MUX). The reverse of this is known as inverse multiplexing, demultiplexing, or demuxing. George O. Squier (1863–1934) invented the principle in 1910 using a carrier frequency to combine multiple telephone signals on one telephone line.

In electrical communications, the two basic forms of multiplexing are time-division multiplexing (TDM) and frequency-division multiplexing (FDM). In optical communications, FDM is referred to as wavelength division multiplexing (WDM).

When encoding video, multiplexing often refers to the process of interleaving audio and video into one coherent stream. In digital television, DVB, ATSC, and ISDB can all multiplex several channels together. In digital radio, both the EUREKA 147 system of Digital audio broadcasting and the HD Radio and Digital Radio Mondiale systems of IBOC can multiplex channels. This is essentially required with DAB-type transmissions, but is entirely optional with IBOC systems.

In spectroscopy the term is used in a related sense to indicate that the experiment is performed with a mixture of frequencies at once and their respective response unravelled afterwards using the Fourier transform principle.

In FM broadcasting and other analog radio mediums, multiplexing is a term commonly given to the process of adding subcarriers to the audio signal before it enters the transmission equipment where modulation occurrs. Multiplexing in this sense is sometimes known as MPX.