That waveform may, for instance, correspond to the sounds to be reproduced amplitude and frequency modulation pdf a loudspeaker, or the light intensity of television pixels. This technique contrasts with frequency modulation, in which the frequency of the carrier signal is varied, and phase modulation, in which its phase is varied. AM was the earliest modulation method used to transmit voice by radio.
It was developed during the first two decades of the 20th century beginning with Landell de Moura and Reginald Fessenden’s radiotelephone experiments in 1900. AM” is often used to refer to mediumwave AM radio broadcasting. This section needs additional citations for verification. Please help improve this article by adding citations to reliable sources.
Unsourced material may be challenged and removed. In electronics and telecommunications, modulation means varying some aspect of a higher frequency continuous wave carrier signal with an information-bearing modulation waveform, such as an audio signal which represents sound, or a video signal which represents images, so the carrier will “carry” the information. When it reaches its destination, the information signal is extracted from the modulated carrier by demodulation. In amplitude modulation, the amplitude or “strength” of the carrier oscillations is what is varied.