Frequency Modulation ( FM )


To generate the Frequency Modulation ( FM ) of a square wave & to observe its characteristics.


Frequency modulation (FM) uses a message's amplitude to vary the frequency of a carrier instead of its amplitude. As such, it is less affected by amplitude variations and so FM is less susceptible to noise. This makes FM a better communications system in this regard.

The main disadvantage of the AM, DSBSC and SSB communication systems is that they are susceptible to picking up electrical noise in the transmission medium (the channel). This is because noise changes the amplitude of the transmitted signal and the demodulators of these systems are designed to respond to amplitude variations.

There are several devices that are capable of generating FM signals, such as VCO or a reactance modulator. Frequency modulation can be regarded as phase modulation where the carrier phase modulation is the time integral of the FM modulating signal.

Fig.1 Showing Message Signal, Un - modulated Carrier & FM Signal.