Which process produces sideband frequencies in a radio carrier?

The process that produces sideband frequencies in a radio carrier is amplitude modulation. In amplitude modulation, the amplitude (or strength) of the carrier wave is varied in accordance with the audio signal being transmitted. This modulation results in the creation of sidebands: the upper sideband (USB) and the lower sideband (LSB). These sidebands contain the information of the original signal and are positioned symmetrically around the carrier frequency.

While frequency modulation and phase modulation also produce variations in the carrier signal, they do so differently and do not produce sidebands in the traditional sense. Frequency modulation varies the frequency of the carrier wave to encode information, and phase modulation changes the phase of the carrier wave, neither of which generates sidebands like amplitude modulation does. Demodulation, on the other hand, is the process of extracting the original information from a modulated carrier wave, and does not play a role in the creation of sidebands.