Associate Certified Electronic Technician Practice Exam

FM modulation, or Frequency Modulation, is characterized by variations in frequency to encode information, distinguishing it from AM modulation, which uses variations in amplitude. In FM, when an audio signal is superimposed onto the carrier wave, the frequency of the wave changes according to the instantaneous amplitude of the audio signal. This means that the carrier wave's frequency increases and decreases in relation to the amplitude of the incoming signals.

This technique allows FM to provide benefits such as improved noise immunity and better overall sound quality compared to AM, which primarily varies the strength of the signal rather than its frequency. By varying frequency instead of amplitude, FM can transmit signals that are less susceptible to interference, leading to a clearer reception in various conditions. Thus, frequency variations are the hallmark of FM modulation.