Modulation is common technique for incorporating informating information, onto a radio -frequency carrier wave by varing one or more characteristics of the wave in accordance with the information signal.
the most commonly altered characteristics are amplitude and frequency.
in amplitude modulation the information is impressed on a carrier wave by varing the amplitude
The AM is the oldest and simplest method for radio trasmission ,
the advantage the signal is easily rcovered in the receiver , the audio signal can be extracted simply by rectifying the receiver's output and then removing the carrier using a capacitor,
in this trassion (AM) uis used for radio broadcasting low and middle frequencies
In frequency modulation (FM) The amplitude of the carrier is costant but the frequency varying in accordance with the variation of the audio signal,
the FM is less suspeptible to certain kind of interference such as thundrestorm
in addition the FM give better qualitysignal than AM in the end FM (frequency modulation) is used for radio and television broadcasting
