Frequency Modulation (FM)

Frequency Modulation (FM) is a type of modulation technique where the frequency of a high-frequency carrier wave is varied in proportion to the amplitude of a low-frequency modulating signal. This results in a modulated signal that contains the original signal at a higher frequency.

The basic block diagram of an FM transmitter includes three main blocks: a modulating signal source, a high-frequency carrier wave source, and a modulator. The modulating signal source generates the low-frequency signal that is to be transmitted. The carrier wave source generates a high-frequency carrier signal that is typically several times the frequency of the modulating signal. The modulator combines the modulating signal with the carrier wave to produce the modulated signal.

Frequency Modulation (FM)

The modulated signal can be expressed as:

s(t) = A_c cos[2πf_c t + 2πk_f ∫m(t)dt]

where A_c is the amplitude of the carrier wave, m(t) is the modulating signal, f_c is the frequency of the carrier wave, and k_f is the frequency sensitivity of the modulator.

FM has several advantages over AM, including resistance to noise and interference, higher bandwidth efficiency, and wider frequency range. FM is commonly used in applications such as commercial radio broadcasting, television broadcasting, and mobile communication systems.

At the receiver, the modulated signal is demodulated to extract the original low-frequency signal. The demodulation process typically involves the use of a frequency discriminator, which converts the frequency variations in the modulated signal back into the original signal.