a) The imposing of a signal on some type of transmission or storage medium, such as a radio carrier or magnetic tape. b) The process (or result) of changing information (audio, video, data, etc.) into information-carrying signals suitable for transmission and/or recording. In NTSC-M television transmission, video is modulated onto a picture carrier using amplitude modulation-virtual sideband, and audio is modulated onto a sound carrier using frequency modulation.