Which of the following is not a significant characteristic of a pulse?

The correct answer is Option (4) → Pulse duration modulation

A pulse in a pulse train is described by its amplitude, its width (duration) and its position in time. In pulse modulation one of these characteristics is varied with the message signal, giving pulse amplitude, pulse width (pulse duration) and pulse position modulation.

Option (1) Pulse amplitude — A characteristic (Incorrect). The height of the pulse, varied in pulse amplitude modulation.

Option (2) Pulse width — A characteristic (Incorrect). The duration of the pulse, varied in pulse width modulation.

Option (3) Pulse position — A characteristic (Incorrect). The time at which the pulse occurs, varied in pulse position modulation.

Option (4) Pulse duration modulation — Not a characteristic (Correct). Pulse duration modulation is a type of modulation, another name for pulse width modulation; it is not a property of a single pulse.

Note: This question is from the pre-rationalised NCERT book (2022-23). The topic was removed from the latest NCERT book (2026-27), and it also appears to be out of the CUET 2026 syllabus.

NCERT (Pre-rationalised edition, 2022-23):
Mixing Up of Signals from Different Transmitters – “… Similarly, the significant characteristics of a pulse are: pulse amplitude, pulse duration or pulse Width, and pulse position (denoting the time of rise or fall of the pulse amplitude) as shown in Fig. 15.7(b). Hence, different types of pulse modulation are: (a) pulse amplitude modulation (PAM), (b) pulse duration modulation (PDM) or pulse width modulation (PWM), and (c) pulse position modulation (PPM).”