What type of modulation interprets waves based on oscillating amplitude?

What type of modulation interprets waves based on oscillating amplitude?

• A. Frequency modulation (FM)
• B. Amplitude modulation (AM)
• C. Phase modulation (PM)
• D. Digital modulation

Answer: (B)

The main idea here is encoding information by changing how tall the wave gets—the carrier’s amplitude. In amplitude modulation, the signal varies the height of the carrier while keeping its frequency and phase essentially the same. As the message increases or decreases, the envelope of the carrier follows that pattern, so the instantaneous amplitude carries the information. You can recognize AM by thinking of radio stations where the strength of the signal ebbs and flows with the audio you’re listening to, even though the tone and speed of the carrier stay constant. In contrast, changing the frequency of the carrier (frequency modulation) or shifting its phase (phase modulation) would alter how fast or where each cycle starts, not how tall the wave is. Digital modulation, meanwhile, uses discrete levels or symbols rather than a continuously varying amplitude.

The main idea here is encoding information by changing how tall the wave gets—the carrier’s amplitude. In amplitude modulation, the signal varies the height of the carrier while keeping its frequency and phase essentially the same. As the message increases or decreases, the envelope of the carrier follows that pattern, so the instantaneous amplitude carries the information. You can recognize AM by thinking of radio stations where the strength of the signal ebbs and flows with the audio you’re listening to, even though the tone and speed of the carrier stay constant. In contrast, changing the frequency of the carrier (frequency modulation) or shifting its phase (phase modulation) would alter how fast or where each cycle starts, not how tall the wave is. Digital modulation, meanwhile, uses discrete levels or symbols rather than a continuously varying amplitude.