FM modulationvaries the frequency of the waves of a carrier in order to transmit analog or digital data. Frequency modulation (FM) is widely used in radio,and TV.
In FM modulation, the frequency of the carrier wave is varied by the incoming signal. In this example, the modulating wave implies an analog signal.
For digital signals, frequency shift keying (FSK) uses two frequencies for 0 and 1 as in this example.