AM vs FM

Radio Terminologies: AM VS FM


It is common to hear the terms AM and FM in the radio. AM and FM are both modes of broadcasting radio signals. These signals transmit electromagnetic waves that carry data or information. AM stands for Amplitude Modulation and was first used in mid 1870s. This type of signal modulates the radio waves or carrier waves or simply carrier by varying the amplitude while keeping the frequency and phase constant. This is because the information is primarily stored in the amplitude. AM signals are cheaper, can be transmitted to farther distances, and can reach more stations due to its lower bandwidth and unrestricted frequency range. The only drawback of AM is that it has a poorer sound quality than FM. It is more susceptible to noise which easily affects the amplitude of the carrier.

FM on the other hand stands for Frequency Modulation and was developed by Edwin Armstrong in the United States. It was first used in 1930s and unlike AM signals, FM varies the frequency instead of the amplitude. The amplitude and phase then remains constant as the necessary information is stored in the frequency. This makes FM less susceptible to interference and noise, and obtain a higher bandwidth resulting to a better sound quality. However, FM signals are more expensive and are affected by physical barriers and reach limited distances only.


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