Let A= (sin(x) * sin(100x)) + sin(100x).; modulation index is 1; Let B= (sin(x) + sin (100x)); Both of these waves have same frequency and both are amplitude modulated. When passed through an envelope detector, both will give message signal. And B have an advantage of not having any sideband frequency. Thus allowing bandwidth to be very short. Then why we use wave A type modulation not B. All the ssb and suppressed carrier wave also use technique A, why not B?