AM broadcasting

AM broadcasting transmits audio by varying a radio-frequency carrier’s amplitude. It is commonly used on medium-wave frequencies and can reach beyond the horizon through ground-wave and skywave propagation.

Radio transmitter: An electronic system that generates and amplifies radio-frequency signals for transmission. It creates and amplifies the modulated signal sent from an AM station.
Radio spectrum: The range of electromagnetic frequencies used for radio communication and broadcasting. AM stations occupy assigned portions of the radio spectrum.
Frequency modulation: A modulation method that encodes information by varying a carrier wave’s frequency. FM varies frequency rather than amplitude and generally resists amplitude noise better.
Skywave propagation: Radio propagation in which waves refract in the ionosphere and return to Earth beyond the horizon. At night, medium-wave AM signals can travel much farther through skywave propagation.
Radio broadcasting: The distribution of audio or audiovisual programs to audiences by radio waves or related transmission systems. AM broadcasting became one of radio broadcasting’s earliest mass-market forms.
Radio receiver: An electronic device that selects radio signals and converts them into usable audio or data. Its tuner and detector recover the audio carried by an AM signal.
Medium wave: The radio-frequency band from roughly 300 kHz to 3 MHz, used for broadcasting and other services. Most conventional AM broadcast services operate in the medium-wave band.
Single-sideband modulation: An amplitude-modulation technique that transmits one sideband while suppressing the carrier and other sideband. It uses spectrum and transmitter power more efficiently than conventional AM broadcasting.
Radio interference: Unwanted signals or noise that disrupt the reception of a radio transmission. AM receivers are especially affected by electrical noise that changes signal amplitude.
Golden Age of Radio: The period when radio was a dominant mass medium for entertainment, news, and drama, especially from the 1930s through the 1950s. AM stations carried the programs that made radio a central household medium.

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