Taajuusmodulatsiooni

Taajuusmodulaatio, often abbreviated as FM, is a method of encoding information in an analog signal by varying the carrier wave's frequency. This is in contrast to amplitude modulation (AM), where the carrier wave's amplitude is varied. In FM, the amplitude of the carrier wave remains constant, while its frequency is changed in proportion to the instantaneous amplitude of the message signal.

The basic principle of FM involves a carrier wave with a constant frequency and amplitude. When a modulating signal, which carries the information to be transmitted, is applied, the frequency of the carrier wave deviates from its center frequency. The amount of this deviation, known as the frequency deviation, is directly proportional to the amplitude of the modulating signal. The rate at which the frequency deviates corresponds to the frequency of the modulating signal.

FM is widely used in radio broadcasting, particularly for music and high-fidelity audio transmission, due to its superior noise immunity compared to AM. This is because most natural and man-made noise sources tend to affect the amplitude of a signal more than its frequency. At the receiver, a circuit called a demodulator or detector extracts the original message signal by measuring the frequency variations of the received FM wave. This ability to reject amplitude variations makes FM signals more robust against interference and fading.