ATPL EASA Radio Navigation Practice Exam 2026 - Free Radio Navigation Practice Questions and Study Guide

The main purpose of amplitude modulation (AM) is to encode information by varying the amplitude levels of a carrier wave. In amplitude modulation, the amplitude of the carrier wave is changed in accordance with the information signal, which could be audio, video, or any other type of data. This modulation process allows the signal to be transmitted over long distances while still preserving the original information, making it possible for radios and other communication devices to receive and decode the message.

This technique is widely used in various broadcasting applications, such as AM radio stations, where the audio signal is superimposed onto a high-frequency carrier wave. The listener's radio demodulates this AM signal to retrieve the original audio sound.

The emphasis on changing amplitude levels to encode information distinguishes AM clearly from other types of modulation, such as frequency modulation or phase modulation, which focus on varying frequency or phase instead.