How does Bluetooth actually work?
Hey friends, Happy Friday!
Let’s look at how Bluetooth works this week. I aim to write my newsletter issues in a way one can follow them while traveling on a bus, having a coffee, waiting for food, etc. Let's jump in!
Tweet of the week
I’m sharing a cool fact about gadgets every day on Twitter. And here is one of them for you
How does Bluetooth work?
Fun fact: The terminology “Bluetooth” was given as a tribute to the Viking king Harald Bluetooth.
Visible light is an electromagnetic wave. Similarly, Bluetooth uses electromagnetic waves but we cannot see with our naked eyes, they are radio waves that lie in a different frequency spectrum. And they can pass through obstructions like how visible light goes through glass. The waves go out as expanding spheres, so your phone and earbuds can be anywhere and they can still connect.
To start off, let’s say we have connected our phones to the earbuds. How does the data communication happen though? Our phones transmit waves with wavelengths between 120.7mm and 124.9mm. The phone sends binary data of 0s and 1s. But how are 0 and 1 encoded and sent as a form of waves?
0s are 1s assigned to different wavelengths. So let’s say, only for example, the phone transmits a 121mm wave - the earbuds can decode it as a 0. And if it transmits a 124mm wave, then it is a 1. Likewise, the packets of data are sent more than a million times a second just by sending waves of different frequencies continuously. And the earbuds can process the 0s and 1s to give us the actual data. There is another catch!
Figure: Phone transmitting binary data in the form of waves of a particular frequency using one of the 79 channels. They hop around channels 1600 times per sec. Source: Branch Education
Figure: Phone transmitting binary data in the form of waves of a particular frequency using one of the 79 channels. They hop around channels 1600 times per sec. Source: Branch Education
Bluetooth transmitters use 79 different channels between 2.4 GHz value and 2.485 GHz. Each channel has a different unique frequency assigned for a 0 and a 1. And so 79 different pairs of wavelengths are used for 0s and 1s. Why are they needed though?
Our phones change the channels they use to transmit 0s and 1s 1600 times every second. So the assigned frequency for a 0 and 1 is never a constant as they keep changing the channels to communicate. Only the transmitter and receiver know the channel they operate on. This is done to prevent eavesdropping by other sources. And this is how Bluetooth communication works!
Question of the week
We looked at how Bluetooth works. But how does WiFi work differently from Bluetooth? Reply to this email with your thoughts, and we’ll have a discussion.
Thank you for reading!
Have a nice rest of the week, and take care!
Until next Wednesday,
Chendur
