How does Bluetooth Work?

Bluetooth is a fascinating technology.

For example, when you play music on your wireless head-phones, your smartphone transmits around

a million 1s and 0s to your headphones every second using Blue-tooth.

These 1s and 0s are assembled into 16-bit numbers which are used to build the electrical

waveform that is sent to the speaker and converted into sound waves.

But how are a million or so 1s and 0s wirelessly transmitted every single second between your

smartphone and your wireless earbuds?

In order to answer this question, we’re going to explore the engineering behind Bluetooth

and the principles of wireless commu-nication.

Before we get into the details and specifics of Bluetooth, let’s start with an analogy.

When you see a traffic light change color, you recognize what that color change means.

The traffic light uses a section of the electromagnetic spectrum, or light, to convey information.

The green light has a wavelength of around 540 nanometers, yellow around 570 nanometers,

and red around 700 nanometers.

Your eyes can easily distin-guish between these different wavelengths of light, and

your brain interprets these different wavelengths and the information they convey.

Your smartphone and wireless earbuds communicate using electromagnetic waves in a rather similar

fashion but utilizing a different section of the spectrum.

Specifically, Bluetooth uses waves that are around 123 millimeters in wavelength.

They are invisible to the human eye and can generally pass-through obstruc-tions like

walls, rather like visible light passing through glass.

When your smartphone sends a long string of binary 1s and 0s to your earbuds, it communicates

these 1s and 0s by designating a wavelength of 121 milli-meters as a 1, and a wavelength

of 124 millimeters as a 0, similar to the 540-nanometer green and 700 na-nometer red

colors of the traffic light.

Your smartphone’s antenna generates these two wavelengths, and switches back and forth

between them at an incredible rate of about a million times a second.

With this pro-cess of switching between the two wavelengths, kind of like switching between

the red and green traffic lights, your smartphone can communicate around a million 1’s and

0’s every single second to your earbuds.

And amazingly, engineers have designed the antennae and circuitry in your earbuds and

smartphone to be attuned to sensing and transmitting these wavelengths back and forth to one another.

Before we dive into further details on Bluetooth, let’s briefly explore and clarify these

visualizations because they’re potentially rather confusing.

First of all, electromagnetic waves do not travel in a single direction in a sinusoidal

fashion like this.

In fact, the electromagnetic waves that are transmitted from your smartphone travel out

in all directions like an expanding sphere.

When your smartphone switches between frequencies, it’s as if it were a lightbulb that rapidly