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

Imagine you and I held either end of a string, how can we “talk” through it?

Way No. 1: I shake my end of the string up and down. I can do really BIG SHAKES or *really small shakes* and the by alternating shakes you could understand them as 1’s and 0’s or dits and dahs (morse code), either way, I can send you a message this way if you know how to read it.

Way No. 2: I *pull* my end of the string away from you and then push it back, the string itself goes slack and tight and slack and tight. Similar to above, you could “read” the tension as a 1 and the slackness as a 0.

AM stands for “Amplitude Modulation” and it’s like way No. 1. The *shape* of the signal is changing and the radio can read that.

FM stands for “Frequency Modulation” and it’s like way No. 2. The *location* of the signal is changing and a the radio can read that too.

In practice it’s not just science jargon, there are some nuanced differences between the signals for the users.

FM signals are typically clearer and higher quality so they are good for music. They also penetrate things better so inside buildings or even some tunnels you can still get the signal clears day.

AM signals travel further and can reflect off the atmosphere to even bend over the horizon so they are good for important communications or long distance communications (like news, government signals, or rural radio stations).

Finally, in the world of digital IOT communications, FM talks *faster* than AM. So you imagined something like transmitting a book via radio waves, FM could send the whole book out before AM finished a paragraph. This is also important for things like military communications. If you’ve ever seen a sub movie, fast signals are blocked by water, so the subs trawl these long radio arrays for slow signals, but they are so slow the signals they get are limited to “go up”. The sub needs to surface and then up the real radio array to receive a full message because it would take hours to transmit even a short broadcast to the sllllloooooowwww under water array.