Angle Modulation MCQs

Practice Angle Modulation MCQs with four options, answers and explanations for focused Electronics & Telecommunication Engineering revision.

Question 1

Communication SystemsAngle Modulation

In frequency modulation, which parameter of the carrier is varied according to the message?

AAmplitude
BInstantaneous frequency
CAverage power only
DAntenna resistance

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Correct Answer: B. Instantaneous frequency

Explanation: FM varies the instantaneous carrier frequency according to the message while ideally keeping amplitude constant.

Reference: Standard communication systems: angle modulation

Question 2

Communication SystemsAngle Modulation

In phase modulation, which carrier parameter is directly varied according to the message?

AAmplitude
BPhase
CAverage DC value
DPropagation speed

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Correct Answer: B. Phase

Explanation: PM varies the instantaneous phase of the carrier in accordance with the modulating signal.

Reference: Standard communication systems: angle modulation

Question 3

Communication SystemsAngle Modulation

For a sinusoidal message in phase modulation, increasing the message frequency while keeping message amplitude and phase sensitivity fixed causes the peak frequency deviation to?

ADecrease
BRemain zero
CIncrease
DRemain independent of frequency

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Correct Answer: C. Increase

Explanation: In PM, instantaneous frequency deviation is proportional to the time derivative of the message, so for a sinusoid its peak value increases with message frequency.

Reference: Standard communication systems: angle modulation

Question 4

Communication SystemsAngle Modulation

In an ideal angle-modulated signal, the total transmitted power is essentially independent of?

ACarrier amplitude
BMessage-induced frequency or phase variation
CLoad resistance in every transmitter
DAntenna efficiency

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Correct Answer: B. Message-induced frequency or phase variation

Explanation: FM and PM have constant envelope in the ideal model, so total average signal power does not vary with modulation index when carrier amplitude is fixed.

Reference: Standard communication systems: constant-envelope power