Frequency Division Multiplexing (FDM)

FDM stands for Frequency division multiplexing. It is the process by which the total bandwidth available to the system is divided. This division is into a series of non-overlapping frequencies bands that are then assigned to each communicating source and user pair.

Frequency division multiplexing (FDM):

  • An analog technique that can be applied when BW of the link is greater than the combined BW of the signals to be T.
  • Signals generated by each sending device modulate difference carrier frequencies.
  • These modulated signals are then combined into a single Composite signal that can be transported by the link.
  • Carrier frequencies are separated by enough BW to accommodate the modulated signal.
  • These BW ranges are the channels through which the various signals travel.

Difference between Frequency Division Multiplexing & Time Division Multiplexing

The total bandwidth present in communication medium are divided. These are divided in series of non-overlapping (guard band provided) frequency called sub-bands. Where they are carrying separate signals. That is allow single transmission mediums such as radio spectrum, a cable or optical fiber to be shared by multiple separate signals.

  1. FDM- Frequency division multiplexing where as TDM mean Time division Multiplexing.
  2. In FDM spectrum is divided into frequency whereas in TDM divided into time slot.
  3. FDM is used in 1st generation analog system whereas TDM is used in 2nd generation analog system.

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