Question
What type of modulation varies the instantaneous power level of the RF signal?
Answer Options
- A) Power modulation
- B) Phase modulation
- C) Frequency modulation
- D) Amplitude modulation
Correct Answer: D
Explanation
The instantaneous power level (amplitude) of the Radio Frequency (RF) signal is directly related to the height of the wave’s envelope. The type of modulation that encodes information by changing the height of this envelope is called amplitude modulation.
In Amplitude Modulation (AM) and Single Sideband (SSB), the modulating signal (e.g., voice) controls the instantaneous power level of the transmitted wave. In contrast, Frequency Modulation (FM) and Phase Modulation (PM) are constant-envelope modes, meaning their instantaneous power level remains relatively constant regardless of the modulating signal.
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