A brief history of Bluetooth

20 November 2025

Bluetooth has liberated us from clutter: thanks to this radio standard, we can wirelessly connect our smartphones to everything from headphones and speakers to cars. But how does Bluetooth work, and how did it get its strange name?

You’ll recognise the scenarios: your mouse and keyboard cables have got all tangled up yet again, and your headphone cable has got snagged in your trouser pocket and is in any case too short to attach your mobile phone to your cycle handlebars for navigation purposes. Bluetooth has freed us from these and other similar entanglements. You simply put your headphones in your ears and wait for the beep announcing a successful connection, and, as if by magic, you can listen to music or podcasts playing on your mobile phone.

For our devices to be able to wirelessly transmit these or other data to each other, each of them has a microchip installed that simultaneously sends and receives Bluetooth signals. To connect, however, they must first find each other, as with an analogue partner search. To this end, we tell our smartphones to search for the headphones. If the latter are in pairing mode, the devices will exchange a security code. After successful pairing, the data will start to flow, and, from then on, our smartphone and headphones will automatically find and connect with each other. Not only that, but each Bluetooth device also has its own 48-bit serial number, which is as individual and unmistakable as a fingerprint.

Bluetooth uses a frequency range of 2.402 to 2.480 gigahertz for its wireless connection. However, the signals from WiFi devices or radio remote controls are also transmitted in the same range. To avoid interference, Bluetooth relies on what is known as frequency hopping: the connection between smartphone and headphones constantly jumps from one of 79 sub-channels to the next – up to 1,600 times per second. If one channel is blocked, this only affects a tiny proportion of the transmitted information, which can easily be picked up elsewhere. This makes Bluetooth connections stable and reliable – provided that the transmitter and receiver are not too far apart.

The idea of automatic frequency hopping goes back to Hedwig Eva Maria Kiesler, better known by her stage name Hedy Lamarr, under which the Austrian actress caused a sensation in Hollywood from the end of the 1930s. As the daughter of Jewish parents, however, she not only wanted to shine on the silver screen but also to play her part in the fight against Nazi Germany. In collaboration with composer George Antheil, the tech-savvy actress developed a radio remote control for torpedoes which used frequency hopping to make it extremely hard for the enemy to localise and disrupt the signal.

However, their invention, patented in 1941, initially went unnoticed and was only rediscovered decades after the Second World War, when it would go on to lay the technological foundation not only for Bluetooth, but also for Wi-Fi and GPS.

It was at the end of the 1980s that the tech companies made their first attempt to clean up the cable clutter associated with computers. But excessive power consumption and susceptibility to failure doomed these initial attempts to failure. In 1994, the Swedish company Ericsson carried out a feasibility study to explore the possibility of a wireless-based alternative to cables. With promising results: in 1998, Ericsson, Nokia, IBM, Toshiba and Intel founded the Bluetooth Special Interest Group, which unveiled the first version of Bluetooth in 1999.

Since then, the transmission speed of Bluetooth devices has increased almost seventy-fold. And a lot has happened in other respects as well. Depending on the device class, transmission power and environment, Bluetooth now allows ranges of anything between one metre and one kilometre. In 2024, a US start-up using special antennae even succeeded in establishing a Bluetooth connection to satellites orbiting the planet at an altitude of 600 kilometres.

Our smartphones usually transmit at an energy-efficient 2.5 milliwatts, giving them a range of up to 50 metres outdoors. Indoors, the connection loses its stability after ten metres, and walls will disrupt the data flow even quicker than that.

In 2009, Bluetooth Low Energy (BLE) was released. Although this has lower ranges and transmission rates, it is particularly energy-saving and responsive. This is why it became the wireless standard of choice for the coronavirus warning app a good ten years later.

Bluetooth owes its name to the Viking king Harald Bluetooth. In the tenth century, he succeeded in uniting Denmark and joining it up with Norway to form an empire – just as Bluetooth pairs mobile phones and headphones today. Having originally been just an internal code name for the new technology, it eventually became a brand name, not least because two Scandinavian companies, Ericsson and Nokia, were significantly involved in its development. The Bluetooth symbol also pays homage to this historical king by combining the runes “Hagalaz” (for H) and “Berkano” (for B) to form the initials HB, which stand for Harald Bluetooth, or Harald Blåtand in Danish.

Hedy Lamarr died in 2000 and thus did not live to see Bluetooth conquer the world. However, three years before her death, the mother of frequency hopping was awarded the Electronic Frontier Foundation Award for her achievements; she was then posthumously inducted into the National Inventors Hall of Fame and honoured in an exhibition at the Jewish Museum Vienna – as “Lady Bluetooth”.