Abkürzung für Frequency Division Multiplexer/Multiplexing
Acronym for Frequency Division Multiplexing. A means of loading multiple transmission signals onto separate bands of a single communications channel so that all signals can be carried simultaneously. FDM is used in analog transmissions, as on a baseband network or in communications over a telephone line. In FDM the frequency range of the channel is divided into narrower bands, each of which can carry a different transmission signal. For example, FDM might divide a voice channel with a frequency range of 1400 hertz (Hz) into four subchannels—820–990 Hz, 1230–1400 Hz, 1640–1810 Hz, and 2050–2220 Hz—with adjacent subchannels separated by a 240-Hz guard band to minimize interference.