Question

Which circuit does the actual multiplexing process in frequency division multiplexing?

(a) Linear mixer

(b) Oscillator

(c) RF amplifier

(d) Duplexer

I got this question in an international level competition.

The origin of the question is Frequency Division Multiplexing topic in division Radio Transmitters, Communication Receivers, Multiplexing and Demultiplexing of Avionics

Answer 1

The correct choice is (a) Linear mixer

Best explanation: The modulator outputs containing the sideband information are added algebraically in a linear mixer; no modulation or generation of sidebands takes place. The resulting output signal is a composite of all the modulated subcarriers. This signal can be used to modulate a radio transmitter or can itself be transmitted over the single communication channel. Alternatively, the composite signal can become one input to another multiplexed system.