Which modulation method is less affected by EMI and provides a clearer signal?

Which modulation method is less affected by EMI and provides a clearer signal?

• A. AM (Amplitude Modulation)
• B. FM (Frequency Modulation)
• C. PM (Phase Modulation)
• D. QAM (Quadrature Amplitude Modulation)

Answer: (B)

EMI and noise tend to disturb the carrier’s amplitude, so a modulation that encodes information in frequency rather than amplitude stays clearer. In amplitude modulation, the information is carried by the carrier’s envelope, so any amplitude noise from EMI directly corrupts the signal. Frequency Modulation keeps the carrier amplitude nearly constant and conveys data through instantaneous frequency changes; this makes amplitude disturbances from EMI less impactful, so the demodulated output remains cleaner. Quadrature Amplitude Modulation uses both amplitude and phase to carry information, so EMI that distorts either can degrade the signal. Phase Modulation encodes in the carrier’s phase, which can be affected by EMI-driven phase disturbances, though it handles some noise differently. Overall, FM provides the clearest signal in the presence of EMI, making it the best choice.

EMI and noise tend to disturb the carrier’s amplitude, so a modulation that encodes information in frequency rather than amplitude stays clearer. In amplitude modulation, the information is carried by the carrier’s envelope, so any amplitude noise from EMI directly corrupts the signal. Frequency Modulation keeps the carrier amplitude nearly constant and conveys data through instantaneous frequency changes; this makes amplitude disturbances from EMI less impactful, so the demodulated output remains cleaner. Quadrature Amplitude Modulation uses both amplitude and phase to carry information, so EMI that distorts either can degrade the signal. Phase Modulation encodes in the carrier’s phase, which can be affected by EMI-driven phase disturbances, though it handles some noise differently. Overall, FM provides the clearest signal in the presence of EMI, making it the best choice.