eli5: what’s the difference between AM radio and FM radio?

Question

i don’t understand when i google it so Whats the difference

In: Technology

Answer 1

AM – Amplitude Modulation. The audio is encoded in changes of the amplitude of the wave … like a on a vinyl record. Big waves means big sound. Long waves means low notes, short waves means high notes.

FM – Frequency Modulation. The audio is encoded in the changes of the frequency of the wave. This is harder to visualize . but Wikipedia’s article on Fourier Transform has a good graphic https://en.wikipedia.org/wiki/Fourier_transform#/media/File:Fourier_transform_time_and_frequency_domains_(small).gif

There is also PM – Phase modulation. Harder still to visualize. This is often used by satelites. Or at least used to be before CM …

CM – Code Modulation. Basically all “channels” are on the same stream of signals, but yo extract your message from the signal you need to apply a code key to filter what is for you (other way around actually, but you get the idea). This is often used in cellphones.

TM – Time Modulation. Think of this as “from >=00:00 until <00:10 everything will be for Alice to read, and from >=00:10 to <00:20 everything will be for Bob to read”. Kind fo boring, but this is basically how ethernet cables work.

There are many variations on the above themes.