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Principles of Communication: Modulation MCQ

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ModulationEasyQuestion 20215

Question

Why is modulation required for long-distance communication?
  1. A
    To increase the wavelength of the signal
  2. B
    To reduce transmitter power
  3. C
    To make antenna size practical and avoid signal mixing
    Correct
  4. D
    To convert digital to analog

Correct answer

To make antenna size practical and avoid signal mixing

Explanation

At audio frequencies (20 Hz – 20 kHz), antenna length λ/2 would be tens of kilometres. Modulation shifts the signal to high carrier frequencies where λ/2 is metres. It also allows frequency-division multiplexing.

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