Frekvenssimodulering

Frekvensmodulering, commonly abbreviated as FM, is a method of encoding information onto a carrier wave by modulating its frequency. In this process, the instantaneous frequency of the carrier wave is varied in proportion to the instantaneous amplitude of the message signal. This stands in contrast to amplitude modulation (AM), where the amplitude of the carrier wave is varied while its frequency remains constant.

FM offers several advantages over AM, notably its superior immunity to noise. External electrical disturbances, such as static, tend to affect the amplitude of a radio wave, not its frequency. Therefore, FM receivers can effectively filter out these amplitude variations, resulting in a cleaner and higher fidelity audio signal. This makes FM particularly well-suited for broadcasting music and other high-quality audio content.

The mathematical representation of an FM signal involves a carrier wave with a constant amplitude and a frequency that deviates from its center frequency according to the modulating signal. The amount of frequency deviation is directly proportional to the amplitude of the message signal. The wider the deviation, the higher the perceived loudness or intensity of the original message.

FM is widely used in radio broadcasting, specifically for the FM radio band (88-108 MHz in most countries). It is also employed in other applications, including wireless microphones, some forms of two-way radio communication, and in the audio component of analog television broadcasts. Despite the advent of digital broadcasting, FM remains a prevalent and robust analog modulation technique.