Amplitude shift keying. The input (digital signal in unipolar NRZ format) is applied to the base of transistor and the carrier is applied to collector.
Input 1 - carrier is present. (1×carrier=carrier)
Input 0 - carrier is absent. (0×carrier=0)
The input(message) is multiplied with the carrier, if the input is 1 we will get the carrier at the output. If the input is zero,the output is also zero.
