In amplitude modulation (AM), which characteristic of the carrier signal is varied to encode the sound information?

In amplitude modulation (AM), which characteristic of the carrier signal is varied to encode the sound information?

• A. Amplitude
• B. Frequency
• C. Phase
• D. Power

Answer: (A)

Amplitude modulation encodes sound by varying the amplitude of the carrier wave. The carrier keeps its constant frequency, but its strength grows and shrinks over time in proportion to the audio signal. This creates an envelope that mirrors the sound waveform, which is how the information is carried. A simple envelope detector at the receiver can extract the audio from that varying amplitude. If you were varying the frequency instead, that would be frequency modulation, and varying the phase would be phase modulation. The basic AM scheme relies on changing the amplitude of the carrier to encode the sound.

Amplitude modulation encodes sound by varying the amplitude of the carrier wave. The carrier keeps its constant frequency, but its strength grows and shrinks over time in proportion to the audio signal. This creates an envelope that mirrors the sound waveform, which is how the information is carried. A simple envelope detector at the receiver can extract the audio from that varying amplitude. If you were varying the frequency instead, that would be frequency modulation, and varying the phase would be phase modulation. The basic AM scheme relies on changing the amplitude of the carrier to encode the sound.