Like it picks up a signal and processes it and from that I can hear music. But is it just the variation in frequency? And if so, then how do stations work?
In: Technology
These are all good responses regarding how radio waves are transmitted and generally how they carry information. I think one aspect that hasn’t been discussed as much yet though is the fact that there is no such thing as “separate” radio/TV/etc signals. When an antenna for example is receiving these electromagnetic waves, it’s not just tuning certain ones. It’s receiving everything, all at once. As you can imagine, this “superimposed” wave is incredibly complex, and would be impossible to do anything with if we couldn’t somehow filter just the signals we want to see.
This is where the radio itself comes in, and more specifically, what we call the RLC Circuit.
* R = Resistor
* L = Inductor
* C = Capacitor
These are the three primary passive components in electrical circuits. Almost everything related to electrical circuits (that doesn’t have some kind of semi-conductor in it) probably consists of one of these three components.
It is difficult to explain in a simple way, but the important thing to know about these components as they relate to electromagnetic signals is that they have a really cool ability to work together to create what we call a “filter” circuit. Using different values for each of them – and some very complicated math – you can figure out the exact size of each one that will tune any frequency (or range of frequencies) that you like.
So let’s say you’re receiving this very complicated signal, but you really only want to tune those EM waves around 650 kHz so you can listen to your favorite AM Sports station. Your radio has an adjustable RLC circuit where it can tune those components just right, so that anything above or below 650 kHz will not resonate in the circuit and will be eliminated completely. This filters out just the frequency you want, effectively restoring it to the original wave that was sent out in the first place.
Of course there is a lot more to it than this, but if you really want to dive into more detail, here’s a great video that really lays everything out from start to finish.
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