Which modulation system alters the amplitude of an RF wave to convey information?

Amplitude modulation is a technique where the amplitude, or strength, of a radio frequency (RF) carrier wave is varied in accordance with the information signal that is being transmitted. This means that as the audio or data signal fluctuates, the amplitude of the RF wave increases or decreases correspondingly. This modulation method allows for the transmission of sound, such as voice or music, over radio waves by effectively encoding the information within the variations of the carrier wave's amplitude.

In contrast, frequency modulation changes the frequency of the carrier wave while keeping the amplitude constant, and phase modulation varies the phase of the carrier wave. Pulsed modulation usually involves sending bursts of RF energy rather than a continuous wave. Each of these other modulation techniques has its own applications and characteristics, but they do not involve the direct alteration of amplitude to convey information as amplitude modulation does.