Full Form of FDM:
Frequency Division Multiplexing
FDM Full Form is Frequency Division Multiplexing. FDM is a channeling concept wherein multiple data signals are collectively used for transmission on a single communications channel via shared medium. FDM uses a carrier signal at a separate frequency for each data and combines many modulated signals. Each signal is assigned a different frequency also called as sub-channel within the main channel. FDM transmits only analog signals hence it is imperative to convert digital signals into analog signals, in order to use them in FDM.
The bandwidth of a link should be greater than the all the bandwidths of the diverse signals to be transmitted. Frequency Division Multiplexing has various applications. It is used in Stereo FM, Television Channels, and Digital Subscriber Line Modems (DSL) etc. FDM is also utilized in communication networks; each input signal is sent and received at maximum speed.
In case many signals are to be transmitted along a single long-distance line, the necessary bandwidth is large; an engineer must take care to ensure that the system will perform correctly. FDM is also used by telephone systems to transmit phone calls through high capacity communications satellites. These satellites are capable of carrying multiple channels of data through FDM. In 21st Century, FDM was rarely used and was replaced by TDM.