Amplitudemoduleret

Amplitudemoduleret, often abbreviated as AM, is a modulation technique used in electronic communication, most notably in radio broadcasting. It involves varying the amplitude of a carrier wave in proportion to the information signal. The carrier wave is a high-frequency radio wave that serves as a vehicle for transmitting the information. The information signal, which could be audio, for example, is superimposed onto this carrier by changing its strength.

In amplitude modulation, the amplitude of the carrier wave is altered according to the instantaneous amplitude of the modulating signal. This means that when the modulating signal's amplitude is high, the carrier wave's amplitude increases, and when the modulating signal's amplitude is low, the carrier wave's amplitude decreases. The frequency and phase of the carrier wave remain constant.

AM broadcasting was one of the earliest and most widespread forms of wireless communication. Its relative simplicity in terms of transmitter and receiver design contributed to its early adoption. AM signals are susceptible to noise and interference, which can manifest as static or unwanted sounds. This is because amplitude variations caused by noise are indistinguishable from the intended amplitude variations carrying the information. Despite its limitations, AM remains in use for certain applications, including long-distance radio, where its ability to propagate over vast distances is advantageous, and in aviation communications.