Amplitude Shift Keying (ASK) is a form of modulation that represents digital data as variations in the amplitude of a carrier signal.  The amplitude of an analog carrier signal varies in accordance with the bit stream (modulating signal), keeping frequency and phase constant.

The simplest and most common form of amplitude shift keying operates as a switch, using the presence of a carrier wave to indicate a binary one and its absence to indicate a binary zero. This type of modulation is called on-off keying. In the FlexTrainer, we are using on-off keying to implement the amplitude shift keying modulation. Figure 1 shows the amplitude shift keying modulation scheme.

Figure 1: Amplitude shift keying

At the end of this experiment, students are encouraged to select different data words and observe the amplitude shift keying modulated waveform for different baud rates on the oscilloscope.