Frequency modulation

Instead of modulating the amplitude of a carrier, as in AM, DSBSC, and SSB, it is possible to send information by modulating the frequency or phase of the carrier.
FM and PM are closely related and are sometimes referred to as "angle modulation".
FM is familiar  as the mode used in the 88-108MHz  VHF broadcast band, and AM is used in the 0.54-106MHz broadcast  band.
Anyone who has tuned an  FM receiver has probably noticed the"quieting" of background noise  characteristic of  FM  reception .IT is the property(the steep rise of recovered SNR with increasing SNR of the channel)that makes wideband FM preferable to AM for high-quality transmission.