The modulation method in which some characteristics of the pulse train are changed according to the instantaneous value of the modulating signal is called Pulse Modulation. In this method, the analog signal is converted into a signal pulse train by coding it according to certain rules and making a digital signal. The process of converting analog signals into pulse trains is called sampling. When these pulses are converted into digital signals, it is called coding.
There are four types of Pulse Modulation. namely-
Pulse Amplitude Modulation (PAM)
Pulse width/duration Modulation (PDM)
Pulse Position Modulation ( PPM)
Pulse Code Modulation (PCM)