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Why does FM sound better than AM?

(www.johndcook.com)
259 points zdw | 1 comments | 13 Oct 24 22:32 UTC | HN request time: 0.206s | source
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massysett ◴[14 Oct 24 00:39 UTC] No.41833059[source]▶
What I’ve never understood is how the FM receiver can lock on to the signal if its frequency is always changing. Doesn’t the receiver need to lock on to something? If the answer is “it locks on to the amplitude, which doesn’t change,” well AM is bad because the amplitude is subject to interference, so wouldn’t FM have the same problem?
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1. Johnythree ◴[14 Oct 24 13:48 UTC] No.41837501[source]▶
Most FM receivers can lock on the carrier because they have a "Phase locked loop" to cancel any tuning errors.

Many good AM receivers do exactly the same thing, especially those receivers which have "Synchronous Detectors" for AM.

It's just that the circuitry involved is simple for FM, but rather more complex for AM.