... modulation,single channel containing analogue information, telephony including sound broadcasting d frequency modulations,double sideband containing analogue information, telephony including soundbroadcasting ... modulation,single sideband,single channel containing digital information,telephony including soundbroadcasting c amplitude modulation,double sideband,single channel containing digital information, ... meansa frequency modulation,single channel containing digital information, telephony including soundbroadcasting b frequency modulation, single channel containing analogue information, morse code...