FDM - frequency division multiplexing
- FDM is an analog multiplexing technique that combines analog signals
- FDM can be used when the bandwidth of a link is greater than the combined bandwidths of the signals to be transmitted
multiplexing process:
- Each sending - device generates modulated - signals with different carrier - frequencies.
- Then,these modulated - signals are combined into a signal multiplexed signal.
- Finally, the multiplexed - signal is transported by link
- Carrier - frequencies are seperated by sufficient bandwidth to accomodate the modulated - signal
- Channels can be seperated by strips of unused bandwidth called guard bands.
- Guard bands prevent signals from overlapping.
- Although FDM is considered as analog multiplexing technique, the sources can produce digital - signal.
- The digital - signal can be sampled, changed to analog - signal, and then multiplexed by using FDM.
demultiplexing process:
- The demultiplexer uses filters to divide the multiplexed signal into individual - signals.
- Then, the individual signals are passed to a demodulator
- Finally, the demodulator
- -> seperates the individual signals from the carrier signals and -> passes the individual signals to output - lines.
