What is the impact of electromagnetic interference on AM signals?

What is the impact of electromagnetic interference on AM signals?

• A. AM signals are unaffected by EMI.
• B. EMI enhances AM signal clarity.
• C. AM signals are more easily affected by electromagnetic interference, resulting in static.
• D. EMI only affects FM signals.

Answer: (C)

The main idea is that AM carries information in the envelope of the carrier, so any disturbance that changes amplitude shows up in the demodulated output. Electromagnetic interference introduces unwanted amplitude variations into the received signal. Since an AM receiver relies on detecting the carrier’s envelope to recover the audio, those extra amplitude changes are interpreted as part of the signal, producing static, hiss, or crackling in the sound. In other words, EMI corrupts the envelope and the audio gets noisy. This is why AM is notably more sensitive to EMI. FM, by contrast, uses frequency changes to convey information and receivers employ limiters that suppress small amplitude variations, so EMI tends to affect it less—though not completely.

The main idea is that AM carries information in the envelope of the carrier, so any disturbance that changes amplitude shows up in the demodulated output. Electromagnetic interference introduces unwanted amplitude variations into the received signal. Since an AM receiver relies on detecting the carrier’s envelope to recover the audio, those extra amplitude changes are interpreted as part of the signal, producing static, hiss, or crackling in the sound. In other words, EMI corrupts the envelope and the audio gets noisy. This is why AM is notably more sensitive to EMI. FM, by contrast, uses frequency changes to convey information and receivers employ limiters that suppress small amplitude variations, so EMI tends to affect it less—though not completely.