Frequency division multiplexing

Frequency division multiplexing (engl. Frequency-division multiplexing , FDM , or frequency-division multiple access , FDMA ) is a communications engineering division multiplexing , with the multiple signals simultaneously on multiple carriers can be transferred distributed. The carriers are assigned to several different frequencies, which is why the term frequency division multiplex is also used. There are a number of other multiplexing methods. For example, with time division multiplex signals are transmitted interleaved in time on a carrier.

Orthogonal Frequency Division Multiplex (OFDM) is mostly used today for the transmission of digital signals as a special implementation of FDM, which uses several orthogonal carrier signals of a digital data transmission in which crosstalk between the multiplexed signals is minimized.

Initially, FDM implementations were expensive because a separate modulator had to be used for each carrier channel. Today, FDM signals can be digitally generated and processed with fast signal processors , the costs of which are so low that this modulation method can be used in mass products with error correction methods and protocol controls also integrated in the signal processors. DSL modems are an example of such products, but there are also other applications such as B. dPMR .