The sigma delta modulation is a digital modulation technique that converts an analog signal into a digital signal preserving its baseband. The sigma delta modulation does not require a carrier rather it uses the analog signal itself for modulation. This technique is economical and simple to implement.

In this technique, the analog signal is sampled at some specific frequency. Each sample of the analog signal is compared to the previous one to determine the increase or decrease in relative amplitude. Increase in relative amplitudes between consecutive samples appears as +1 at output and decrease in relative amplitudes appear as -1 at the output. Figure 1 shows sigma delta modulated signal.

Figure 1: Sigma delta Modulation

At the end of this experiment, students are encouraged to carry out practical observations by generating different waveforms from the signal generator and varying step sizes from the transmitter.