Which modulation method does the picture below belong to?

Question

Exhibit

Options

• AAM
• BFM
• CPhasing
• DModulation

• A
  4% (1)
• B
  82% (23)
• C
  11% (3)
• D
  4% (1)

Explanation

FM (Frequency Modulation) is correct because the image shows a carrier wave whose frequency changes in response to the message signal while its amplitude remains constant - the defining characteristic of FM. AM (Amplitude Modulation) is wrong because it works the opposite way: the carrier's amplitude varies with the message signal, not its frequency. "Phasing" is not a standard modulation category; it may refer loosely to Phase Modulation (PM), which is a separate technique where the phase, not the frequency, is shifted. "Modulation" is the overarching term for the entire family of techniques and cannot be a specific method.

Memory tip: In FM, think "Frequency Moves" - the waves bunch together and spread apart as the signal changes, which you can spot visually by the varying spacing between wave cycles.

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