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Why does FM sound better than AM?

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259 points zdw | 2 comments | 13 Oct 24 22:32 UTC | HN request time: 0s | source
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matrix2003 ◴[14 Oct 24 00:15 UTC] No.41832921[source]▶
Someone gave me an analogy some time ago that made a lot of sense.

If you shine a flashlight through a tree blowing in the wind and vary the brightness to convey information, the signal can get distorted pretty easily.

However, if you have a constant brightness source and vary the color, it’s a lot easier to figure out what the source is trying to convey.

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beala ◴[14 Oct 24 01:10 UTC] No.41833220[source]▶
This makes a lot of sense so long as your source of noise is something like a tree swaying in the wind, ie something that interferes with the amplitude. If instead the source of noise is uhhh a piece of stained glass swaying in the wind then blinking the flashlight is the better bet. I guess it just turns out radio interference is more like the tree. But why?
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1. a-dub ◴[14 Oct 24 06:01 UTC] No.41834635[source]▶
a better analogy for frequency domain interference would be something like the spinning flashing lights on a fire engine or utility truck occasionally shining colored light on your detector.
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2. mkehrt ◴[14 Oct 24 19:09 UTC] No.41840802[source]▶
I think this is reasonable analogy, for FM interference, and it points out why FM is resilient to noise: the flashing lights have to be relatively bright (high amplitude) to interfere with your color based scheme.