Multiplexing
From Free net encyclopedia
In telecommunications, multiplexing (also MUXing) is the combination of two or more higher level channels into a single lower level channel such that a reverse process, known as inverse multiplexing, demultiplexing, or demuxing, can extract the original channels. The individual channels are identifiable by a predetermined coding scheme.
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). Time-Division Multiplexing can be either synchronous or asynchronous.
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 occurs. Multiplexing in this sense is sometimes known as MPX.
See also
- Multiplexer
- Time-division multiplexing
- Frequency-division multiplexing
- Orthogonal frequency-division multiplexing (OFDM)
- Code-division multiple access (CDMA)
- Codec (coder-decoder)
- Polarization-division multiplexing (PDM)
- Statistical multiplexing
References
de:Multiplexverfahren fr:multiplexage hu:Multiplexálás ja:多元接続 pl:Multipleksowanie