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 carrier wave frequency is modified as per the transmit data. In contrast, in amplitude modulation, the carrier wave is modified according to the data.
For instance, if several 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 of how radio broadcasts are done.
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, which helps them travel long distances. Sometimes AM signals can be able to bounce off the ionosphere. The distance travelled by the AM is much larger than the FM.
Read More: Amplitude Modulation
Frequency Modulation
In this module, the carrier wave frequency 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. Frequency modulation also enables to transmit stereo signals.
| Difference Between AM and FM | |
| Amplitude Modulation (AM) | Frequency Modulation (FM) |
| The first successful audio transmission was carried out in the mid-1870s | Developed in 1930 by Edwin Armstrong, in the United States |
| The radio wave is called a carrier wave, and the frequency and phase remain the same | The radio wave is called a carrier wave, but the amplitude and phase remain the 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 the higher spectrum |
| More susceptible to noise | Less susceptible to noise |
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