How Does Bluetooth Work?

Bluetooth is a technology which connects gadgets seamlessly. The purpose of Bluetooth is to help us listen to audio without a wire. It is one of the best wireless inventions of all time. We use Bluetooth technology in smartphones, cars, TVs, PCs, laptops, and many other devices. It is Bluetooth which has made our lives easier. Using a Bluetooth device is easy. All you need to do is connect the devices by switching on the Bluetooth. If you are sending or receiving files to and from a phone, all you need to do is press a button and it will be activated. But have you ever wondered how that works?

What is the technology behind Bluetooth which allows a file to be transferred from your smartphone to another? Have you ever thought how that audio file on your smartphone is played on your laptop using Bluetooth? What is the science behind it? Here is an explanation of the workings of Bluetooth.

How it works – In simple words

Simply put, Bluetooth uses radio waves to transfer signals from one device to another. Each device that you connect needs the Bluetooth technology. It requires both the hardware and software to work. The hardware necessary for Bluetooth is a chip which receives and sends signals. It is an antenna-based chip, which means that it has a built-in antenna technology. The chip sends and receives signals at a particular frequency. The frequency used to send and receive signal depends on the type of hardware. Once the chip sends the data via Bluetooth, the receiver (software) at the other end interprets the incoming Bluetooth signals.

When you play audio via Bluetooth on a speaker, the device will send the data in such a manner that it will be understood by the speaker. An acknowledgment signal is necessary to connect to the Bluetooth device. The Bluetooth device which sends the data also sends a message. This message has information to alter the Bluetooth devices in range. Once the connection gets established, it is called a piconet or a PAN (personal area network).

This is how Bluetooth works in a layman’s language.

How it works –In technical words

Just like any other wireless technology, Bluetooth works with frequencies. It operates at the ISM (industrial, scientific and medical) band. The frequency used by Bluetooth is between 0.4 to 2.485 GHz. Bluetooth uses a spread spectrum, and it also uses a frequency hopping mechanism to send and receive data. It works on 1600 hops/sec. Bluetooth uses Gaussian frequency modulation and gives the baud rate of 1 MB per second.

With the frequency hopping technique, the data is transmitted from one device to another in the form of packets. The sender and receiver transmit data at one frequency and hop onto another frequency to send and receive the next piece of data (packet).

Each Bluetooth device (chip) has an address and a clock rate. The devices have a unique 48-bit address, and this address is assigned to the device at the time of manufacture. This address cannot be modified. The Bluetooth works on a 28-bit clock that ticks every 312.5 microseconds. Bluetooth devices are connected only when they have each other's address and clock rate.

As mentioned before, the network formed by Bluetooth devices is called the piconet. In the piconet, there is one master and all other devices are slaves. The master is the device which creates the network and sends the data to the other devices in the network (or to the slaves).

Bluetooth devices operate at different levels, and these levels have different maximum range. The Class 1 Bluetooth devices have a range of 100 meters, Class 2 Bluetooth devices can transmit data at a distance of 50 meters, and Class 3 has a range of 10 meters.

The Bluetooth technology has evolved in the past few years. There are various algorithms and techniques which are used to compress the data while transferring over Bluetooth. These algorithms allow the Bluetooth technology to operate not only faster but with better quality as well.


Dr. Stephen Smyth developed aptX in 1994. The purpose of aptX is real-time data compression while transferring. This technology is now used in Bluetooth devices to stream HD content at a faster rate. aptX is a strategy used to enhance the audio quality, and today almost every device utilizes the aptX codec.

Bluetooth devices which operate with aptX technology provide better sound quality. aptX also provides low latency. Latency is the time a device takes to encode and decode the signal. With aptX, Bluetooth devices can transmit data at a faster rate. The rate at which aptX runs is 354 kilobits per second.

This codec works on ADPCM (Adaptive Differential Pulse Code Modulation). The term adaptive differential means that aptX predicts the next signal before transmitting it instead of sending a complete audio sample. Bluetooth devices with the aptX codec work better than the devices which work on other codes such as AAC.


NFC stands for Near Field Communications. It is a short-range wireless technology used for communication and is a way of sending data using radio signals. The data is only transmitted if the devices are placed at a close distance. It is a faster mode of transmission as compared to Bluetooth but has a small range (10cm). Mobile phones which have the NFC chip can detect other mobile phones or devices with the same technology just by holding the phone close to each other. It means that the connection between the two devices starts automatically as soon as you bring the devices close to each other.

However, that doesn't mean that it will start sharing data automatically. It will prompt a message on the screen, asking if you would like to share or "beam" content to the other device. It is much more secure than Bluetooth and can also be used to make payments.