When frequency division multiplexing (FDM) is used to aggregate several modulated channels together, no separation between channels (i. e., use of guard channels) is required. True False

False.

Separation between channel is required when frequency division multiplexing (FDM) is used to aggregate several modulated channels together.

Explanation:

In Frequency Division Multiplexing (FDM), the total bandwidth is divided to a set of frequency bands that do not overlap. Each of these bands is a carrier of a different signal that is generated and modulated by one of the sending devices.

The frequency bands are separated from one another by strips of unused frequencies called the guard bands, to prevent overlapping of signals.

The modulated signals are combined together using a multiplexer (MUX) in the sending end. The combined signal is transmitted over the communication channel, thus allowing multiple independent data streams to be transmitted simultaneously. At the receiving end, the individual signals are extracted from the combined signal by the process of demultiplexing (DEMUX).