In telecommunications and signal processing, frequency modulation FM conveys information over a carrier wave by varying its instantaneous frequency.his contrasts with amplitude modulation, in which the amplitude of the carrier is varied while its frequency remains constant. In analog applications, the difference between the instantaneous and the base frequency of the carrier is directly proportional to the instantaneous value of the input-signal amplitude. Digital data can be sent by shifting the carrier39s frequency among a range of settings, a technique known as frequency-shift keying FSK. FSK is widely used in data and fax modems, and can be used to send Morse code.Radioteletype also uses FSK.2 Frequency modulation is also used in telemetry, radar, seismic prospecting and newborn EEG seizure monitoring. Frequency modulation is known as phase modulation when the carrier phase modulation is the time integral of the FM signal. FM is widely used for broadcasting music and speech, two-way radio systems, magnetic tape-recording systems and some video-transmission systems. In radio systems, frequency modulation with sufficient bandwidth provides an advantage in cancelling naturally-occurring noise.