Photo of a radio, showing the frequency scanner.

I’m pretty sure most of you have listened to the radio. You might have listened to it from your car’s media player, from a mobile phone or even an actual radio. If you do not know what it is, it is basically a machine we use to listen to ‘radio stations’. You might have listened to something like this: “This is 98.5FM”. Now, try to make sense of ‘98.5 FM’. Yes, it makes no human sense. But surely, they must mean something.

Here might be what is going through your mind: What is 98.5 there for? What is ‘FM’? We will have answered all of this by the end of this post. So here are some things you might have noticed when using a radio:

  1. It has these ‘radio stations’ denoted by numbers.
  2. On each number, you hear different things.
  3. But in numbers between two stations, say ‘98.5’ and ‘96.4’. On ‘95.7’, there is just this white noise.

This might seem like just random gibberish, but trust me, it isn’t.

So let’s ask some questions on this “radio” thing. How is data wirelessly transferred? How can we hear sound from it? Why are there so many numbers!?

What is radio?

So let’s get started from the basics. In what form is this data transferred? The answer is in the name. Radio. Radio uses radio waves, which are what we call ‘electromagnetic radiation’. Now here is a secret: electromagnetic radiation is actually light!

That’s right, the songs you hear from the radio are brought to you by light! I know what you’re thinking: Geez Venkat. Stop being so silly. Obviously, it’s not light! We can’t see them.” But actually, what we think of light as, what we see, is just the smallest part of it. The seven colours of the rainbow are the only colours we can see. But the actual spectrum is bigger. It goes below red and above violet. way above and below. These we can’t see, as they are not in our visible spectrum (the rainbow).

You might have heard of infrared, ultraviolet, and so on. Just like these, there exists a spectrum very low. This is the Radio spectrum (by low and high I mean more energy and lesser).

So radio is a kind of light. But remember, it is a spectrum of light. So that means, it is a range of colours of light. Now that we know what ‘radio’ is, we can investigate more.

How it works

Let’s answer all of these questions.

How is data wirelessly transferred? How can we hear sound from it?

So as we just saw, it is transmitted using light and is converted to sound by our radio systems. That explains a lot! Now we can easily answer the other questions.

What do these numbers mean like ‘98.5’?

So here is what they are. Imagine if everyone tried to transmit in the same light (spectrum). We would have multiple people talking over each other. That’s not what we want, so each person uses a different frequency of light (basically you can think of that as a colour in the radio colour spectrum since it is light). So 98.3 is actually 98.3 Mhz, which is the light’s frequency. So now, they can play anything on it, and no one else will. That is a lot better, since now everyone talks on their own ‘station’. This can be used to categorize into different genres and so on. So that’s what those numbers meant. That is a lot more clear now, isn’t it? Let’s move on to another one.

What is the FM for?

You have probably seen ‘Radio FM’. You might not have seen it, but there exists another as well, called ‘Radio AM’. What do these mean?

Well, FM stands for Frequency Modulation. It basically means that we change the frequency. These are used to carry the information in the light to encode the sound data. AM uses amplitude modulation, meaning the difference in sound is carried by differences in amplitude of the light.

We have finally uncovered what ‘98.3 Mhz FM radio’ means! We have come a long way from thinking it was just random gibberish. Here is a quick summary:

  • Radio works by transmitting light
  • It has different frequencies to differentiate between these ‘stations’
  • Commonly FM or frequency modulation is used to carry the information through.

The way it works is not mysterious, but rather simple. Now you know how the radio works!

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