Difference Between AM And FM

Amplitude modulation and frequency modulation are used to transmit data using the method of modifying a carrier signal. The main difference between both modulations is that in frequency modulation, the frequency of carrier wave is modified as per the transmit data. While, in amplitude modulation, the carrier wave is modified according to the data.

For instance, if several different sets of data are required to be transmitted using the same medium, then each set off is sent using different frequency waves. This is the process how radio broadcasts as done.

AM And FM

Amplitude Modulation

Amplitude modulation is a modulation technique where the amplitude of a carrier varies depending on the information signal. AM radio broadcast signals use lower carrier frequencies, this helps them to travel longer distances. Sometimes, AM signals can be able to bounce off the ionosphere. The distance travelled by the AM is much larger than the FM.

Frequency Modulation

In this module, the frequency of the carrier wave is modified according to the signal that carries information. The radio signals have large bandwidth than AM radio signals, which helps to offer much better sound quality. It also enables to transmit stereo signals.

Difference Between AM and FM

Amplitude Modulation (AM) Frequency Modulation (FM)
First successful audio transmission was carried out in mid-1870s Developed in 1930 by Edwin Armstrong, in the United States
The radio wave is called as a carrier wave and the frequency and phase remain same The radio wave is called a carrier wave, but the amplitude and phase remain same.
Has poor sound quality, but can transmit longer distance. Has higher bandwidth with better sound quality
The frequency range of AM radio varies from 535 to 1705 KHz The frequency range of FM is 88 to 108 MHz in higher spectrum
More susceptible to noise Less susceptible to noise.

Practise This Question

When a current changes from + 2A to – 2A in 0.05s, an emf of 8V induced in a coil. The coefficient of self induction of coil is: