Frequency Divison Multiplexing
Frequency Division Multiplexing (FDM) is primarily used with analogue signals rather than digital data streams.
It works by dividing the entire bandwidth which is available in a data source, into sub-channels that each have a different frequency; hence the name ‘frequency division’. Each sub-channel then carries separate signals through a transmission line or an aggregated channel (a combination of channels with higher bandwidth).
The sub-channels can travel independently through a transmission line or they can travel simultaneously besides one another. These two travelling types represent two types of transmissions that we use every day.
When you listen to your radio, either through amplitude modulation (AM) or frequency modulation (FM), the multiplexer generates a single station that you can tune into. We are able to decide to listen to just one station because each individual data stream that is being transmitted is regulated by a provider. If this wasn’t happening, we would hear unwanted static interference as the signals would overlap. This is very much the same with television broadcasting, and the same process allows us to separate the data in to channels.
FDM is normally transmitted through coaxial cable, optical fiber or using a radio transmitter.
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