What type of modulation is characterized by the variation of pulse duration?

Pulse-width modulation is characterized by the variation of pulse duration, which refers to how long each pulse lasts within a given time frame. In this modulation type, the width of the pulses changes to convey information, rather than altering the amplitude or the frequency of the signal. This method is commonly used in various applications, including motor control and telecommunications, due to its efficiency and effectiveness in transmitting signals over long distances.

The focus on pulse duration is what distinguishes pulse-width modulation from other types of modulation. For instance, amplitude modulation involves varying the strength (amplitude) of the signal, while pulsed amplitude modulation also focuses on changes in amplitude but typically retains constant pulse width. Quantized modulation refers to the process of constraining the amplitude or frequency to discrete levels rather than continuously, which differs from the principles governing pulse-width modulation.