What is the difference between AM and FM radio and why is FM more popular?
In: Technology
I’ll attempt a slightly more ELI5 explanation.
“Modulation” in this case, is basically a way to encode an audible signal into a signal beyond the range of human hearing.
AM or Amplitude Modulation is encoded in such a way that the decoder (a radio or similar device) rebuilds the original audible signal based on the changing amplitude (think “loudness”) of the broadcast signal. This is cheaper and can be transmitted further than an FM signal, but the main downside is that it isn’t as robust. If the signal has to go through a wall or something to reach the radio, the signal can be attenuated (made “quieter”), which will change the decoded audio. AM tends to be used for talk radio rather than music because of this.
FM or Frequency Modulation, on the other hand, is encoded in such a way that the decoder rebuilds the original signal based on the changing frequency (or pitch, if you’re musically inclined) of the broadcast signal. This is more robust than AM, because as long as the signal is strong enough for the radio to pick up, the frequencies will be the same, and therefore the signal will be reproduced correctly. This is why FM tends to be used for music (FM stations also have more bandwidth so music sounds better than it would on AM, but that’s somewhat outside the scope of this post).
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