Question

In a Quadrature Amplitude Modulation (QAM) scheme, information is encoded in:

• A. Only phase of the carrier
• B. Only frequency of the carrier
• C. Both amplitude and phase of the carrier
• D. Only amplitude of the carrier

Hint:

QAM = Amplitude + Phase modulation combined.

Answer 1

The Correct Option is C

Concept: QAM combines:
• Amplitude modulation
• Phase modulation

Step 1: Signal representation \[ s(t) = I \cos(\omega t) + Q \sin(\omega t) \] Where:
• $I$ → in-phase component (amplitude)
• $Q$ → quadrature component (phase)

Step 2: Conclusion Information is encoded in both amplitude and phase. \[ \therefore \text{Correct answer is (C)} \]