Which statement best describes frequency modulation?

Frequency modulation (FM) is characterized primarily by the way that the carrier wave is altered in response to the information signal. In FM, the carrier frequency is varied in accordance with the amplitude of the incoming information signal, while its amplitude remains constant. This is a distinctive feature of frequency modulation, as it ensures that the signal can convey information without the variations equating to amplitude changes, which can be more susceptible to noise and interference.

By relying solely on frequency changes to represent the information, FM can provide better sound quality, particularly in broadcasting, as well as a greater immunity to amplitude-related noise. This makes FM particularly advantageous for radio communications and broadcasting, as it can enhance the clarity and quality of the transmitted signal.

The other statements describe various aspects or potential misconceptions about FM. For instance, the second option incorrectly implies that both amplitude and frequency are altered, which does not accurately represent the fundamental principle of frequency modulation. The third statement suggests that FM is significantly affected by atmospheric noise, which is generally not the case; FM is more resistant to noise compared to amplitude modulation (AM). Lastly, the fourth statement mentions high-level mixing, which is not a defining feature of FM in the way described. Consequently, the first statement remains the clearest and most