Difference between Amplitude Modulation and Phase Modulation

Last Updated : 15 Jul, 2020

Prerequisite – Modulation

1. Amplitude Modulation :
Amplitude Modulation is a modulation in which the amplitude of the carrier wave changes according to the instantaneous amplitude of the modulating signal keeping phase and frequency as constant. The amplitude of the carrier wave is modified in order to send the data or information. It can transmit over long distances, have a large range. Its modulation index varies from 0 to 1. In Amplitude Modulation, the frequency and phase remain the same.

2. Phase Modulation :
Phase Modulation is a modulation in which the phase of the carrier wave changes according to the instantaneous amplitude of the modulating signal keeping amplitude and frequency as constant. Phase Modulation and Frequency Modulation are similar, but in Phase Modulation frequency of the carrier signal is not increased. Phase Modulation is used in mobile system. The phase of the carrier wave is modified in order to send the data or information.

Difference between Amplitude Modulation and Phase Modulation :

S.NO.	Amplitude Modulation	Phase Modulation
1.	In Amplitude Modulation, the frequency remains the same.	In Phase Modulation, the amplitude remains the same.
2.	It has simple circuit.	It has complex circuit.
3.	Its modulation index varies from 0 to 1.	Its modulation index is always greater than one.
4.	Noise immunity is poor than in PM.	Noise immunity is better than in AM.
5.	In Amplitude Modulation, the phase remains the same.	In Phase Modulation, the frequency remains the same.
6.	Amplitude Modulation is widely used.	Phase Modulation is used in mobile system.
7.	Signal to noise ratio is better than Phase Modulation.	Signal to noise ratio is poor than Amplitude Modulation.
8.	The amplitude of the carrier wave is modified in order to send the data or information.	The phase of the carrier wave is modified in order to send the data or information.
9.	In AM, received signal is of low quality.	In FM, received signal is of high quality.
10.	It has better sound quality.	It has poor sound quality.