Frequency modulation (FM) is a form of angle modulation wherein the instantaneous frequency of a carrier signal is varied proportionally to the amplitude of the modulating message, distinct from phase modulation which varies the instantaneous phase directly. The theoretical framework establishes that FM signals possess constant envelope power and are characterized by parameters including the frequency deviation ($\Delta f$), maximum message frequency ($W$), and the dimensionless frequency modulation index ($\beta_f = \Delta f / W$). This mechanism enables a significant signal-to-noise ratio improvement at the demodulator output, proportional to the square of $\beta_f$, by trading increased bandwidth for superior noise immunity compared to amplitude modulation.
Frequency modulation (FM) is a form of angle modulation wherein the instantaneous frequency of a carrier signal is varied proportionally to the amplitude of the modulating message, distinct from phas…