eli5 how cell phones work


Please eli5 how I am able to talk into my cell phone and it’s able to send my voice across the globe and be undistorted coming through the other ends speaker. Just can’t grasp how it’s carried over through from my phone to the tower to the next one and so forth.

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Your voice is picked up by a tiny microphone on your phone, which converts sound into electrical signals.

Electrical signals are transformed into bits (0s and 1s) by something known as an “analog to digital converter”, which periodically looks at the signal and stores the value of the signal at that exact time. The value is a number and any number can be represented, with some accuracy, by a sequence of 0s and 1s.

At this point you have a very long sequence of 0s and 1s. That sequence is split into “packets”, smaller sequence of 0s and 1s, much like you can split a book’s content into words and lines. Each packet contains both your voice and some additional information about your phone, the other guy’s phone and so on.

Each of those packets is translated back into an “analog”, continuous signal by a “digital to analog converter”, which is really the opposite of the analog to digital converter we saw before.

An analog signal is an electrical signal which goes through an antenna. The antenna generates radio waves and transmits your packet to the closest tower. The tower talks to the rest of the network managed by your phone provider, which can in turn interact with other providers even around the world. Ultimately, that packet reaches the tower serving your friend.

At that point the tower sends that packet to your friend. Your friend’s phone has an antenna which picks up the signal converts into digital form (0s and 1s), does some processing, and then returns the digital voice signal to a digital to analog converter, which creates an analog electrical signal, which is sent to a speaker, which translates electrical signals into voice your friend can hear.

The way it’s sent over long distances is with light. Not visible light, invisible wavelengths (basically “colors”). These wavelengths have an easier time going through most materials than visible light, which is why you don’t need line of sight to the tower.

By the way, the sound isn’t completely undistorted. The microphone and speaker aren’t perfect, the analog-to-digital signal converter causes some lost “resolution”, and there’s probably lossy compression (data compression that doesn’t perfectly preserve all the data) so there’s less data to send.