how does Bluetooth work?


I remember my first audio system, it was a DVD player, the first few days I was so excited about it that I listened to my favorite playlist for hours non-stop. Every day I wake up and the first thing I did was to turn it on and pop in a DVD which had my favorite songs in it.

Well since then technology came a long way now you can just connect your phone to a Bluetooth speaker or headphone and listen to your favorite playlist on Spotify.

Do you ever wonder how these fancy Bluetooth devices work? I mean all you have to do is turn on your phone's Bluetooth and pair it to your Bluetooth speaker and there you go, you can now listen to your favorite playlist without having to deal with that old technology. It is so simple, isn't it?




So how exactly do Bluetooth works?


Before explaining how it works, lets first dive into a brief history of Bluetooth technology


The idea of what we called Bluetooth today was actually first introduces back in 1989, by DR. Nils Rydbeck and inventor DR. Johan Ullman, they had a great idea to develop a pair of wireless headsets because well, wires are annoying right? After extensive discussion sessions, they brought DR. Jaap Haartsen to the project, after 5 years of research and experimentation they successfully came up with the first protocol, it took them a few more years to perfect the technology, but in 1999 they presented their first handsfree Bluetooth headset at the COMDEX computer expedition and trade show held in Las Vegas. And that was the beginning. The name "BLUETOOTH" though was actually derived from a king named Harold Bluetooth Gormsson. Anyway let's not go there.


Now for the actual question. How does it work?


Well, Bluetooth works a lot like WIFI, it uses radio wave to transmit data between devices at a short distance, now whereas WIFI transfer data between your router and another device, Bluetooth transfer data between devices, that means if two devices have a Bluetooth option it can be used to transfer data between each other. Both WIFI and Bluetooth uses a radio wave frequency centered at 2.4 GHz (now some WIFI routers also use 5GHz band), but Bluetooth actually works at lower distances thus known as short-range wireless communication.

Bluetooth consumes a lot less power than WIFI, that is a reason why Bluetooth doesn't interfere with other wireless devices. You can simultaneously use your Bluetooth mouse on your laptop and also connect your Bluetooth headset to your phone without having to deal with interference issues. In fact up to eight Bluetooth devices can communicate with each other at a time.

When let's say two devices want to connect to each other, it uses the principle of device "inquiry" and "inquiry scan". Scanning devices listen in on known frequencies for devices that are actively listening.

Let's say you want to print something wirelessly via Bluetooth when you submit the print signal from your phone the printer (scanning device) which was listening for inquiries picks up that signal and the name of that printer comes upon you mobile screen when u hit pair the two devices exchange a set of security keys (which is kinda like a conversation between the two devices to verify the data pair and successfully connect to each other), once connected successfully, it starts printing.

Similarly, when you connect to a Bluetooth speaker it uses the inquiry and inquiry scan principle to first identify each other and then pair/connect to each other by sharing security keys, after successful pairing you are now able to stream data(music in this case).


Bluetooth sends and receives radio waves in a band of 79 different frequencies(channels) centered on 2.45 GHz, when a group of one or more Bluetooth devices is sharing information together, they form a mini-computer network known as a piconet. And when any of the multiple Bluetooth devices connected together wants to transmit data it randomly picks a channel that is not being used by any other device this technique is known as spread-spectrum frequency hopping (it is an algorithm that is determined by the master device, it allows pseudorandom ordering of the 79 frequencies available).


And all these complex processes go without the user actually noticing any backend algorithms. Thus the story of the great success of Bluetooth explained.

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