What is the process of varying the frequency of a carrier wave in proportion to the amplitude of the modulating signal called?

The process of varying the frequency of a carrier wave in proportion to the amplitude of the modulating signal is known as frequency modulation (FM). In FM, the frequency of the carrier wave changes according to the fluctuations in the amplitude of the input signal. This means that as the amplitude of the modulating signal increases or decreases, the distance between cycles of the carrier wave is either compressed or expanded, resulting in a change in frequency.

Frequency modulation is particularly effective in reducing the impact of noise and interference on the transmitted signal, which is a significant advantage in radio communications. This robustness against noise makes FM a preferred choice for high-fidelity broadcasts and communications, such as music and speech transmission.

Amplitude modulation, on the other hand, involves varying the amplitude of the carrier wave while keeping the frequency constant, which is a different process entirely. Phase modulation alters the phase angle of the carrier signal based on the modulating signal but does not involve frequency variation directly. Pulse modulation encodes information in pulses rather than in continuous waves, making it distinct from frequency modulation as well.