What is the difference between AM and FM radio and why is FM more popular?
In: Technology
Humans can hear sound roughly between 20 and 20,000 Hz (Hz = one cycle per second, 20 Hz = 20 cycles per second). In this case, each “cycle” is the air being compressed and decompressed, which we understand as sound.
Radio waves can have a frequency higher than that. So, what if we encode the sound wave into a radio wave? Or in simpler terms: what if we “draw” the sound wave using radio waves?
There are (at least) two ways we can “draw” the sound wave: when the sound wave is in the “compressing” part, we make the radio wave more intense, and when it’s in the “decompressing” part we make it less intense. This would be AM radio.
The other way would be for the frequency to get higher when “compressing”, and lower when “decompressing”.
[Here’s a GIF explaining it.](https://upload.wikimedia.org/wikipedia/commons/a/a4/Amfm3-en-de.gif) The signal would be the sound wave, the higher the line the higher the pressure. Notice how AM basically makes the intensity of the signal follow the curvature of the sound wave while using the same frequency all the time, while in FM the intensity doesn’t change, but the new signal gets faster and slower.
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