How do mobile phones work, or any phone on that matter? I talk in a phone and my voice comes out another phone pretty much immediately – many miles away.
In: Technology
First, let’s understand a classic telephone.
Electricity and magnetism are connected. One of the astounding properties of this is that if you drag a magnet past a wire, it will generate an electric current in the wire. The opposite is also true; putting a charge on that wire will cause the magnet to experience a force, nudging it slightly.
You speak into a microphone. All a microphone is, is a little magnet sitting on a tiny trampoline that allows it to vibrate when it’s hit by noises in the air. This magnet is suspended next to a coil of wire. When the magnet moves, it creates charges in this wire. Those charge signals will be created in a pattern that exactly mirrors the vibrations that created them. That means, if you amplify these signals, send them over long distance electrical wire to another, bigger magnet on a trampoline somewhere else (also known as a speaker, in this case another telephone), that magnet will be jiggled in the exact same way. Attach it to a big enough trampoline, and it will shake the air in the same way it bounces. That will make it mimic the exact same sound that was sent to it.
In principle, a classical landline phone physically connected you to every other telephone you could possibly call by an electrical wire, somewhere, and you would communicate using that principle above. What makes a classical cell phone different is that for part(s) of that signal transfer, you’re not actually using a wire.
Instead of putting the signal over a wire using electrical currents, a cell phone has to convert the sound data to a radio signal and send it through an antenna. This uses light waves. Your phone is essentially “shouting” your phone call to a nearby radio tower, that is listening to your call and re-translating it back into a signal that can be sent over a wire. That wire then connects back into the phone system and everything else is mostly like before. If you’re calling another cell phone, it does this in reverse; your phone call connects to a tower somewhere else in the world close to the phone you’re trying to call, and the tower “shouts” the phone call to that device, which is “listening” for it and translating it on the fly.
So… what I’ve described so far are “analog” systems, that encode messages directly using electrical currents or radio frequencies. Only the *very early* cellular networks were analog systems (1G, which wasn’t even called that at the time). Any cellular network you’ve probably ever used was already a “digital” system. That basically means, all the data encoding your voice sounds are crunched through a computer algorithm to turn it into binary data. This binary data representation of your voice is not an *exact* representation of the sound you just made, but it’s so close that for all serves and purposes, no one would notice the difference.
So, the way your phone *actually* works, is after it gets the electrical signal of your voice from a microphone, it sends it to a special computer that can read in analog data and convert it to binary on the fly. This binary data is thrown into a buffer, basically a little queue for 1’s and 0’s where they wait to be sent out in chunks. Like a bunch of little people queuing to get onto an airplane. Once the phone has enough data in the buffer, that data gets wrapped up in a little package (literally called a “packet”) and this whole block of data is “shouted” at the tower. This packet is routed through a system that behaves somewhat like the Internet (or if your phone has IP voice functionality, it *does* use the Internet) to route it to the tower that will “shout” it to the phone you’re trying to call. That phone reads the packet, decodes it back to an analog wave signal, and drives the speaker.
This all happens very quickly. Your phone is screaming a deluge of voice data packets in rapid succession, and they reach your target at about the speed of light over the phone network. The other device is rapidly decoding these packets and turning them back into audible noise at about the same rate as they’re coming in. Minus a very slight delay due to limitations in the speed of light and the tiny amount of time it takes to encode and decode these data packets, the result is a virtually seamless, nearly instant voice transmission.
Your girlfriend’s phone turns her voice into radio waves.
Those waves travel across the planet very fast and reaches your phone.
Your phone turns those radiowaves back into voice.
And boom you’re single now.
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