How does Bluetooth Work?

Summary

This script delves into the engineering marvel of Bluetooth technology, explaining how millions of bits are wirelessly transmitted between devices every second. It uses an analogy of traffic lights to illustrate the concept of electromagnetic waves, discusses the specifics of Bluetooth's frequency range, and introduces packet transmission and frequency hopping to ensure reliable communication. The script also touches on interference from other devices and the technical intricacies of data transfer, such as frequency and phase shift keying.

Takeaways

• 🎧 Bluetooth technology transmits data wirelessly using electromagnetic waves, with the smartphone sending millions of 1s and 0s to wireless headphones every second.
• 🌐 The 1s and 0s are assembled into 16-bit numbers, which form the electrical waveform sent to the speaker and converted into sound waves.
• 📡 Bluetooth operates in the 2.4 GHz frequency range, utilizing wavelengths around 123 millimeters, which are invisible to the human eye and can pass through obstacles.
• 🌈 The technology uses a section of the electromagnetic spectrum similar to how traffic lights use different wavelengths of light to convey information.
• 🔄 Bluetooth devices communicate by switching between two specific wavelengths to represent binary 1s and 0s, similar to the concept of traffic light colors.
• 🔢 Electromagnetic waves from Bluetooth devices propagate in all directions, like expanding spheres, allowing for omni-directional communication.
• 🔁 Bluetooth employs frequency hopping spread spectrum, switching between 79 different channels 1600 times a second to avoid interference and ensure secure communication.
• 📚 Data is sent in packets with access codes, headers, and payloads, ensuring that only the intended device receives the message, much like addressing a postal letter.
• 🔍 Bluetooth devices are designed to filter out unwanted noise and detect errors, maintaining reliable communication despite potential interference from other devices.
• 🛠️ The shared 2.4 GHz frequency range with other devices like microwaves and Wi-Fi networks is managed through frequency hopping and error detection to prevent signal loss.
• 🔑 Advanced methods like phase shift keying can be used for higher data transfer rates in Bluetooth, involving shifts in the phase of electromagnetic waves.

Q & A

How does Bluetooth transmit data wirelessly between devices?

Bluetooth transmits data wirelessly by sending a million 1s and 0s every second using electromagnetic waves. These binary digits are assembled into 16-bit numbers that create an electrical waveform, which is then converted into sound waves by the speaker.

What is an analogy used to explain the concept of Bluetooth communication?

The script uses the analogy of a traffic light to explain Bluetooth communication. Just as traffic lights use different colors with specific wavelengths to convey information, Bluetooth devices use different wavelengths of electromagnetic waves to transmit data.

What is the typical wavelength used by Bluetooth technology?

Bluetooth typically uses wavelengths around 123 millimeters, which are in the 2.4 to 2.4835 Gigahertz frequency range of the electromagnetic spectrum.

How does the human eye perceive different wavelengths of light?

The human eye perceives different wavelengths of light as different colors. For example, green light has a wavelength of around 540 nanometers, yellow around 570 nanometers, and red around 700 nanometers.

How do Bluetooth devices avoid interference and ensure exclusive communication?

Bluetooth devices avoid interference and ensure exclusive communication by using frequency hopping spread spectrum. They hop between 79 different channels 1600 times a second, sending packets of information that include access codes to synchronize the devices.

What is the purpose of the access codes in Bluetooth communication packets?

The access codes in Bluetooth communication packets serve to synchronize the devices, ensuring that the message is sent to and received by the intended recipient, similar to how address words on a postal letter ensure it reaches the correct destination.

How does the frequency hopping spread spectrum technique work in Bluetooth?

Frequency hopping spread spectrum involves rapidly switching between different frequency channels, sending one packet of information after each hop. This technique helps avoid interference, adapt to crowded channels, and prevent eavesdropping.

Why might Bluetooth headphones lose signal when a microwave is in use?

Bluetooth headphones may lose signal when a microwave is in use because both operate within the same frequency range of 2.4 Gigahertz. However, the script emphasizes that Bluetooth headphones are not dangerous, despite this similarity in frequency.

How does Bluetooth handle the transmission of data in both directions between devices?

Bluetooth handles bidirectional data transmission by alternating between transmitting and receiving data while maintaining the frequency hopping schedule. During one timeslot, the smartphone sends data to the headphones, and during the next, the headphones send data back to the smartphone.

What is the significance of the term 'payload' in the context of Bluetooth packets?

In the context of Bluetooth packets, 'payload' refers to the actual data or information being sent, such as the digital 1s and 0s that make up audio. The size of the payload can vary widely, depending on the data requirements, ranging from 136 bits to 8168 bits.

How does the script differentiate between the principles of antenna theory and the functioning of traffic lights?

While both traffic lights and Bluetooth devices use the electromagnetic spectrum, the principles governing their generation and reception of electromagnetic waves are different. The script likens this to how fire and an electric radiator both generate heat but through different methods.

Outlines

00:00

🔊 Understanding Bluetooth Technology

This paragraph delves into the intricacies of Bluetooth technology, explaining how it enables wireless communication between devices like smartphones and headphones. It uses an analogy of traffic lights to illustrate the concept of transmitting information through different wavelengths of the electromagnetic spectrum. The script clarifies that Bluetooth operates at a specific wavelength, approximately 123 millimeters, which is invisible to the human eye and can penetrate obstacles. It also explains the process of encoding binary data into these wavelengths and the rapid switching between them to transmit data at a high rate. The paragraph further explores different visualizations of electromagnetic waves to help the viewer understand the propagation and reception of Bluetooth signals.

05:03

📶 The Mechanics of Bluetooth Communication

This section of the script focuses on the technical aspects of Bluetooth communication, including the specific frequency range it operates within and how it uses multiple channels to avoid interference. It explains the concept of packets, access codes, headers, and payloads in the context of Bluetooth data transmission. The paragraph also introduces the idea of frequency hopping spread spectrum, where Bluetooth devices rapidly switch between 79 different channels to ensure reliable communication and security. It touches on the adaptability of Bluetooth devices to avoid noisy channels and the process of retransmitting lost packets to maintain error-free data transfer.

10:03

🛠️ Exploring the Practicalities of Bluetooth Interference

The script addresses the practical issues of Bluetooth interference, particularly with devices like microwave ovens and Wi-Fi networks that operate within the same frequency range. It dispels the myth that Bluetooth headphones are dangerous due to their similar frequencies to microwaves and emphasizes the importance of proper shielding. The paragraph also discusses how Bluetooth devices handle interference through frequency hopping and error detection, using the analogy of a brain filtering out irrelevant visual information to focus on important signals, such as a traffic light.

15:06

🌐 Advanced Bluetooth Technologies and Sponsorship Acknowledgement

This paragraph introduces more advanced Bluetooth technologies such as frequency shift keying and phase shift keying, which are methods of transmitting information through electromagnetic waves. It also acknowledges the sponsorship of the video by KIOXIA, a company that provides flash memory and SSDs for various devices, including those that use Bluetooth technology. The script highlights the differences between consumer and enterprise class SSDs and invites viewers to learn more about KIOXIA's products.

20:09

🎧 The Bidirectional Nature of Bluetooth Communication

The final paragraph discusses the bidirectional communication capabilities of Bluetooth, where both the smartphone and headphones can send and receive data. It explains the alternating transmission and reception of data while maintaining the frequency hopping schedule. The script also provides further details on the composition of Bluetooth packets, including the variable size of the payload depending on the data requirements. Lastly, it emphasizes the unique principles governing the generation and reception of electromagnetic waves in Bluetooth technology compared to other devices like traffic lights.

Keywords

💡Bluetooth

Bluetooth is a wireless technology standard for exchanging data over short distances using short-wavelength UHF radio waves in the ISM band from 2.4 to 2.485 GHz. It is integral to the video's theme as it explains how Bluetooth enables communication between devices, such as smartphones and wireless earbuds, through the transmission of millions of 1s and 0s every second.

💡Electromagnetic Waves

Electromagnetic waves are waves that carry electromagnetic energy and have electric and magnetic field components oscillating perpendicular to each other and perpendicular to the direction of travel. In the context of the video, Bluetooth utilizes these waves in the form of radio waves to transmit data, with the script providing an analogy of traffic light wavelengths to illustrate the concept.

💡Wavelength

Wavelength is the physical distance between two corresponding points in consecutive cycles of a wave. The video uses the term to describe the specific lengths of electromagnetic waves that Bluetooth technology employs, such as the 123 millimeters wavelength, to convey information between devices.

💡Frequency Hopping Spread Spectrum (FHSS)

Frequency Hopping Spread Spectrum is a method of transmitting radio signals by rapidly switching the carrier frequency among many different frequency channels, using a pseudorandom sequence known to both the transmitter and the receiver. The video explains that Bluetooth uses FHSS to avoid interference and to ensure secure communication by hopping 1600 times a second between 79 different channels.

💡Binary

Binary is a system of numerical notation to the base 2, in which typically only two symbols, 0 and 1, represent values. The video script explains that Bluetooth technology transmits data in the form of binary digits, which are assembled into packets and sent between devices.

💡Packets

In the context of data transmission, a packet is a unit of data sent across an inter-network, which is divided into chunks to be transmitted over the network. The script describes how messages in Bluetooth communication are assembled into packets that include access codes, headers, and payloads to ensure the data is sent and received accurately.

💡Phase Shift Keying (PSK)

Phase Shift Keying is a type of digital modulation where the phase of a carrier signal is changed to represent the digital information being sent. The video mentions PSK as an alternative method to frequency shift keying for higher data transfer rates, involving the phase of electromagnetic waves rather than frequency.

💡Frequency Shift Keying (FSK)

Frequency Shift Keying is a type of frequency modulation where the frequency of a carrier signal is changed in proportion to the amplitude of a modulating signal. The video script uses the analogy of a traffic light to explain FSK, where different frequencies represent different binary values in the transmission of data.

💡Interference

Interference in the context of wireless communication refers to the disruption that occurs when two or more electromagnetic waves combine, leading to a reduction in signal quality. The script explains how Bluetooth devices adapt by avoiding noisy or crowded channels to minimize interference.

💡Microwave Oven

A microwave oven is used as an example in the script to illustrate the shared frequency range with Bluetooth, operating at 2.45 GHz. The video points out that while microwave ovens can interfere with Bluetooth signals, Bluetooth devices are not dangerous due to the similarity in frequency.

💡Antenna Theory

Antenna theory is the study of the behavior of antennas, which are used to transmit and receive electromagnetic waves. The video script mentions that the principles behind how Bluetooth devices generate and receive electromagnetic waves fall under antenna theory, which is a broader subject to be explored in a separate episode.

Highlights

Bluetooth technology transmits a million 1s and 0s per second to wireless headphones.

1s and 0s are assembled into 16-bit numbers to create the electrical waveform for sound reproduction.

Bluetooth uses electromagnetic waves with a wavelength of around 123 millimeters.

The human eye cannot see Bluetooth wavelengths, which can pass through obstacles like walls.

Smartphones communicate binary data by switching between two designated wavelengths.

Bluetooth operates within a frequency range of 2.4 to 2.4835 Gigahertz.

The electromagnetic spectrum is divided into 79 channels for Bluetooth communication.

Bluetooth devices use packets with access codes, headers, and payloads for data transmission.

Frequency hopping spread spectrum is used to prevent interference and eavesdropping.

Bluetooth can retransmit data if packets are not received due to interference.

Bluetooth's frequency range overlaps with other devices like microwaves and Wi-Fi.

Bluetooth uses frequency shift keying and phase shift keying to transmit information.

Bluetooth devices alternate between transmitting and receiving data.

Bluetooth packets consist of access codes, headers, and payloads that can vary in size.

The principles of Bluetooth are distinct from those of visible light and traffic lights.

KIOXIA BiCS Flash Memory is used in many Bluetooth devices for storage.

Transcripts

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

changes between two different frequencies of millimeter length electromagnetic waves,

which travel out as expanding spheres.

As a result, your smartphone and wireless headphones can work in any di-rection.

Thus, this visualization of a directional sinusoidal wave is lacking, yet there are

still merits to the vis-ualization.

In order to give you a sense of how Bluetooth works, we’re going to use 4 different visualizations

that are all different perspectives of looking at the same invisible thing.

Here we have the sinusoid waves which give us a sense of the frequency and wavelength

of the electromagnetic wave.

What’s moving up and down is not the wave itself, but rather it’s the strength of

the electric field.

This perspective just shows us a directional sliver or ray of the expanding sphere with

the electric field going up and down as the Bluetooth signal propa-gates outwards in all

directions.

If we were to measure the electric field at a single point in space, we would find that

the strength of the electric field would increase and decrease sinusoidally, and the number

of peaks per second would be the frequency.

Furthermore, we’re ignoring the magnetic field component of the elec-tromagnetic wave,

as including it would be too confusing.

Let’s move onto the second visualization.

Here we have the travelling binary numbers which give us a sense of the data being sent,

however it also doesn’t show the spherical propagation of the electromagnetic waves or

the changing frequency of the wave.

Note that it’s possible to send multiple bits at the same time which we’ll explore

later.

Third, we have the expanding spheres visualization, which gives a sense of the true near-omnidirectional

emission of electromagnetic waves from your smartphone and headphones, but it’s difficult

to show the frequency or the data that’s being sent, and it's rather visually complex

to process.

And last, we have the simplified spheres, which help us see that these two devices are

emitting and receiving electromagnetic waves along the same frequencies, but it doesn’t

show us much else.

Different visualizations are useful in different scenarios, and with that covered, let’s

get back to the focus of this video.

As mentioned, Bluetooth operates at around 123 millimeters of wavelength, but specifically,

it oper-ates between 120.7 millimeters and 124.9 millimeters of wavelength in the electromagnetic

spectrum.

Note that, these frequencies are more commonly referred to as having a 2.4 to 2.4835 Gigahertz

frequency band-width or range.

Just as our eyes see within a range on the electromagnetic spectrum, Bluetooth anten-nas

see or perceive within their own range of frequencies . Now, at any given time, there

might be dozens of people using Bluetooth devices at the same time in the same room.

To accommodate so many users, this section of the electromagnetic spectrum is broken

up into 79 different sections or channels, with each chan-nel having a specific wavelength

for a 1, and another for a 0 and at any given moment your Smartphone and earbuds communicate

across just one of these channels.

For example, these are the frequencies for a 1 and a 0 in channel 38, whereas these are

the frequencies for channel 54.

Now this begs the question: if dozens of devices are using the same wavelengths and possibly

the same channel, how do your earbuds receive long strings of binary bits, or messages from

your phone exclusively.

Well first, the messages are assembled into packets.

In each packet, the first 72 bits are the access codes that synchronize your smartphone

and earbuds to make sure that it’s your specific earbuds that receive the message.

These access codes are similar to the address words on a postal letter or package.

Just a few lines of writing and a stamp can send a letter, which is seemingly identical

to millions of other letters, to the exact house or address anywhere in the world.

The next 54 bits are the header which provides details as to the information being sent,

which in our analogy can be equated to the size of the letter or the box.

And the last 500 bits are the actual information or payload, kind of like the contents of our

postal letter or box, which in this case are the digital 1s and 0s that make up the audio

that you are listening to.

If you’re wondering how audio can be represented by 1’s and 0’s take a look at this episode

on audio codecs.

Ok, so now let’s add more complexity to the mix.

As mentioned, Bluetooth operates in a set of 79 dif-ferent channels.

However, when your smartphone and earbuds communicate, they don’t stick to a single

channel, but rather they hop around from channel-to-channel kinda like channel surfing on your TV.

In fact, this hopping between the 79 channels, which is called frequency hopping spread spectrum,

happens 1600 times a second, and after each hop one packet of information composed of

the address, header, and payload, is sent between your smartphone and earbuds.

Your smartphone dictates the sequences of channels it will hop to, and your earbuds

follow along.

Furthermore if one of the 79 channels is noisy due to interference or is crowded with other

users, then your smartphone adapts and doesn’t use that channel until the noise clears.

This channel hopping also prevents anyone from eavesdropping on the information that

is being sent between the two devices, because only your smartphone and earbuds know the

sequence of channels that they will communicate across.

Interestingly, because the information is divided and sent using packets, if your earbuds

don’t receive one of the thousands of packets, it says it didn’t receive that particular

one , and your smartphone sends the packet again.

It might seem crazy or mind blowing that the circuitry in your phone can generate pulses

of electro-magnetic waves a million times a second at very specific frequencies and

then have these pulses received and decoded by your earbuds- but hey- it happens.

Just think about how your screen has millions of pixels, also emitting specific frequencies

and strengths of the electromagnetic spectrum, or light at around 30 to 60 or more times

a second.

Technology is fascinating.

One quick side note: We would greatly appreciate it if you could take a second to like this

video, sub-scribe to the channel, comment below, and share this video with others.

A few seconds of your time can help us to create many more educational videos.

Thank you!

Okay, let’s move on.

One point of interest is that Bluetooth’s frequency range of 2.4 Gigahertz to 2.4835

Gigahertz is shared by other industrial and medical devices.

For example, your microwave is in this range and has a frequency of 2.45 Gigahertz.

In fact, when your microwave is on, it can cause your head-phones to lose track of the

1s and 0s being sent by your smartphone, or in other words your headphones can lose signal.

However please don’t think your Bluetooth headphones are dangerous because they emit

a wavelength that’s similar to your microwave’s.

That would be like comparing the light output from stadium floodlights to the light from

your smartphone screen, and saying that, because they both use the same colors of light, they

will both cause damage when stared at from a foot away.

Also, remember we mentioned that the electromagnetic waves from Bluetooth can easily travel through

obstacles such as the walls of your house?

However, the walls of the microwave are designed to block waves of this frequency.

You can test this by putting your smartphone in the microwave; the Bluetooth signal from

your smartphone to your headphones will be blocked, and the connection lost.

However, make sure NOT to turn on your microwave with any electronic devices inside of it,

I repeat, do NOT turn on your mi-crowave otherwise it WILL damage whatever electronics you put

into it.

In addition to microwave ovens, 2.4 Gigahertz Wi-Fi networks also operate within this range

of the electromagnetic spectrum.

Similar to Bluetooth, Wi-Fi networks divide this range or bandwidth into 14 chan-nels

in order to accommodate multiple users communicating via Wi-Fi at the same time.

You might be won-dering, if there are a bunch of different devices all sharing similar frequencies,

one of them being a microwave that, if poorly shielded, can emit stray electromagnetic waves,

how is it possible for your smartphone and headphones to send megabits of data every

second, error free?

Well, as mentioned earlier, your smartphone does this by frequency hopping, and utilizing

packets.

In addition to that, Bluetooth also utilizes bits for de-tecting errors and the circuitry

in your smartphone filters out unwanted noise.

For a non-technical under-standing of this, let’s go back to our traffic light analogy.

When you’re driving and you see a traffic light, it’s not like that’s the only thing

you can see.

Your eyes perceive a rather complex scene filled with tons of other objects.

Your brain interprets this information-filled scene and picks out the information important

to you, while ignoring all the objects that aren’t.

Similarly, your smartphone and wireless headphones have rather complicated circuitry inside a

specialized Bluetooth microchip that’s designed and tested by engineers, which filters out

unwanted signals, checks for errors, coordinates the frequency hopping, and assembles the infor-mation

into packets thereby enabling reliable and secure communication.

Before we move onto some higher level-engineering concepts, we’d like to take a few seconds

to thank KIOXIA for sponsoring this video.

Many Bluetooth devices such as mobile phones and tablets use KIOX-IA BiCS Flash Memory.

KIOXIA also manufactures a wide variety of SSDs and they have sponsored a couple of our

videos that explore the inner workings behind how SSDs work.

Here’s a consumer class SSD, versus this enterprise class SSD.

They look similar from the outside but are entirely different on the inside.

KIOXIA pro-vides these leading quality enterprise class PCIe NVMe solid state drives, and they

can fit in the same space, but have capacities up to a whopping 30 Terabytes, and use a proprietary

architecture built with their own controller, firmware, and BiCS Flash 3D TLC memory in

order to deliver incredibly high sustained read and write performance and reliability.

Check out KIOXIA’s SSDs using the link in the description.

Let’s move on to even more complicated details regarding Bluetooth.

The scheme of sending a digital signal, or a binary set of 1’s and 0’s by transmitting

different frequencies of electromagnetic waves is called frequency shift keying.

Frequency shifting means that we adjust the frequency, and keying means that a 1 is assigned

to one frequency, and a 0 to another, just like our traffic light colors.

Note that the comparison to a traffic light which emits one color and then another is

a little inaccurate because your smartphone’s circuitry generates one frequency, called

a carrier wave.

This circuitry shifts the carrier wave to a higher frequency when it wants to send a

1 or to a lower frequency when it wants to send a 0.

This shifting of frequencies in order to send information is also called frequency modulation,

and it’s closely related to FM radio.

That being said, Bluetooth isn’t limited to using just frequency shift keying; but

rather it can also use other properties of electromagnetic waves to transmit information.

A different method that has higher data transfer rates is called phase shift keying, which

is a significantly more complicated to explain but we’ll try.

An electromagnetic wave’s phase is a property that our eyes can’t perceive, and it shouldn’t

be confused with the amplitude or the frequency or the wavelength.

Let’s use an analogy.

Imagine you’re at the beach and you see the waves hitting the shore at a rate of one

wave a second.

Over a minute you would see 60 wave peaks reach and break on the shoreline.

Changing the frequency would be changing how many wave peaks reach the shoreline every

second and changing the amplitude would be changing the height of the peaks and troughs

of the waves.

However, phase shifting would be seen as breaking up the waves’ locations of the peaks and

the troughs within a set of wavelengths.

There are still 60 waves over an entire minute, meaning the frequency doesn’t change, but

as the phase shifts, it’s as if the peaks and troughs shift forward or backward within

a set of wavelengths.

Bluetooth antennas and circuitry in your smartphone and wireless earbuds can be designed to emit

and detect shifts in the phase of an electromagnetic wave, and binary values can be keyed, or assigned

to dif-ferent levels of shifts in the phase of the wave.

There are a few things to note with our examples and explanations.

We’ve talked a lot about your smartphone sending information to your wireless earbuds;

however, your earbuds also send data to your smartphone.

For example, when you’re on a phone call using your earbuds, the audio from the microphone

in your wireless headphones is obviously sent back to your smartphone.

In order for Bluetooth to accommo-date this back-and-forth conversation, the smartphone

and the headphones alternate transmitting and re-ceiving data, while maintaining the

frequency hopping schedule.

During one 625 microsecond timeslot, your smartphone will send one packet of data to

your headphones along one channel, and then during the next 625 microsecond time slot

your headphones will send one packet of data to your smartphone along the next channel

in the frequency hopping schedule.

Also, as we mentioned earlier, a Bluetooth packet is composed of 3 sections: access codes

of 72 bits, a header of 54 bits, and for example a payload of 500 bits.

The number of bits in the access codes and header are pretty close to those mentioned,

however the size of the payload which is specified using the header can vary widely between 136

bits and 8168 bits depending on the requirements of the data being sent.

For exam-ple, simple commands from your headphones like pause or play the music would require

far fewer bits than sending or receiving high quality audio.

An additional caveat is that the electromagnetic waves sent and received from the antenna in

your smartphone and earbuds, and the light from a traffic light, share the aspect that

they both function within the electromagnetic spectrum.

However, the principles that govern how your smartphone and headphones gen-erate and receive

those electromagnetic waves are quite different from the principles around how traffic lights

and your eyes work.

It’s kind of like how fire and an electric radiator both generate heat but using vast-ly

different methods.

The principles behind Bluetooth fall under the category of antenna theory and will be

explored in a separate episode.

Thus far we’ve made a few episodes that help to explain other parts of these wireless

headphones such as noise cancellation and the audio codec, and we’ve made even more

episodes that dive into the dif-ferent parts of your smartphone.

Check them out to learn about these other fascinating technologies.

We believe the future will require a strong emphasis on engineering education and we’re

thankful to all of our Patreon and YouTube Membership Sponsors for supporting this dream.

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