Hirose: Connecting the future
Industrial Ethernet Book Issue 103 / 17
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Harald Blåtand, king of Denmark, Norway and Wireless

Harald was the the son of King Gorm the Old and of Thyra Dannebod, and became king of Denmark in the year 958. He introduced Christianity to Denmark and consolidated his rule over Jutland and Zealand. He might be largely forgotten today, had he not had a bad tooth that appeared "blue".

THIS BAD TOOTH LED TO King Harald′s nickname "Blåtand". which means Bluetooth. In 1941, Swedish writer Frans Bengtsson included king Bluetooth in his historical adventure novel "The long ships".

46 years later, a copy of this book landed on the desk of Jim Kardach. He was a design engineer at Intel, working on a "short-link" radio technology. He proposed the name Bluetooth for this new technology, as he hoped that it would unite the different communication protocols into one universal standard, just like king Harald had united the Scandinavian countries.

Hagalaz und Berkanan

This nordic origin is still present in the Bluetooth logo, which combines the old runic symbols Hagalaz und Berkanan.

The runic symbols Hagalaz and Berkanan form the Bluetooth logo.

While the vikings conquered Scandinavia, Bluetooth went on to conquer the whole world. Today, the Bluetooth Special Interest Group (SIG) has more than 30,000 members, and experts assume that there is an installed base of nearly 10 billion Bluetooth-enabled devices worldwide.

The proud longships of king Harald and his Vikings

It started with headphones

The development of a short-link wireless standard was initiated at Ericsson Mobile, mainly to develop wireless headsets. The engineers opted for short-wavelength UHF radio waves in the globally unlicensed 2.4 to 2.485 GHz industrial, scientific and medical (ISM) band.

Bluetooth is a packet-based protocol with a master/slave architecture, where one master may communicate with up to seven slaves. The master defines the basic clock, with 625 µs defined as one transmission slot. The master transmits in even slots and receives in odd slots, for the slaves it works the other way around.

To ensure a reliable connection, Bluetooth uses frequency-hopping spread spectrum (FHSS), rapidly switching the carrier frequency channels in a sequence that is known to both transmitter and receiver. The inventors of this technology are the Austrian actress Hedy Lamarr, who had fled from Nazi Germany, and composer George Antheil. They developed this method to make US forces radio communications harder for enemies to detect or to jam.

Bluetooth divides transmitted data into packets, and transmits each packet on one of 79 designated Bluetooth channels. Each of these channel has a bandwidth of 1 MHz, and Bluetooth hops between these frequencies 800 times per second.

Hedy Lamarr, contemplating frequency-hopping spread spectrum technology

Originally, Gaussian frequency-shift keying (GFSK) modulation was used, which limited the bandwidth to 1 Mbit/s. The introduction of Bluetooth 2.0 in 2004 allowed the use of differential quadrature phase shift keying, increasing the bandwidth to 3 Mbit/s.

Different flavours

With ongoing development. Bluetooth today comes in three different "flavours".

Classic Bluetooth, in Basic Rate or Enhanced Data Rate, is still the dominant cable replacement technology. It is what we all use for wireless keyboards, mice, speakers and headsets.

Bluetooth Low Energy (LE), introduced in 2010, is optimised to use as little energy as possible. Powered by only a coin-sized battery, it can often last for years. Almost every smartphone or tablet today supports Bluetooth LE.

The latest addition is Bluetooth mesh, which was launched this summer. It is intended to make the technology better suited for IoT applications. Classic Bluetooth is a startopology in which all devices are connected to a central hub, which limits the network range to the furthest connected device. In the mesh network, all devices communicate with each other, which makes the area covered by the network almost unlimited.

Beyond wireless speakers

So what can Bluetooth do beyond connecting speakers or keyboards to our tablets and PCs? To find this out. the Bluetooth SIG organizes the annual Imagine Blue Awards. Designers develop solutions that push the boundaries of wireless connectivity. Here are some creative projects from the Imagine Blue competition.


After Sara Du got lost in the mountains, she developed the concept of Bluejay, a combination of software and hardware that is able to find missing people.

Bluejay is a drone that uses an onboard Intel Edison computer and Bluetooth technology to communicate with both people in need of rescuing and rescuers.

While cellular service may fail in such situations, Bluetooth would still function, so the drone could communicate with cell phones and facilitate rescues.


While we may not get lost at home, our car keys sometimes do. That′s where TrackR comes in. It creates a virtual floor plan of a users home and helps track frequently misplaced items. After attaching the coin-sized TrackR bravo to keys, wallet or phone, the TrackR app can locate it in seconds.

One smart feature is that the app even helps you find items that you misplaced outside your home through a crowd-sourced network.

When another TrackR user is within Bluetooth range of the lost item, the owner will receive a location update. Also, the app records the last known location on a map, so at least you know where to start searching.


The Novalia project brings touch-based interactivity to virtually any printed material.

Paper thin self adhesive touch sensors from printed conductive ink are combined with a microcontroller module that handles processing and Bluetooth communications. Touching the sensors controls apps on a smart phone or laptop. A single CR2016 coin cell powers the system for up to one year.

Using this technology, Novalia created what the world had been waiting for a long time: The first playable pizza box OJ decks. The Pizza Hut boxes come in a design modelled on a modern OJ set-up. They feature two turntables, a cross-fader, pitch volumes, cue buttons and the ability to ′rewind′ the music. The decks sync via Bluetooth to the user′s smartphone with OJ software such as Algoriddim′s DJAY Pro. The sound is produced from the smartphone or computer, which can be linked to external speakers.

The OJ decks work by sensing human touch through conductive ink and can differentiate between taps, long presses and even swipes of the finger in any direction. This allows music and pizza fans to mix and scratch their own OJ sets by tapping and sliding their fingers over the controls.

It′s really a shame that this was only a one-off promotion and limited to just a few of the Pizza Hut restaurants.

Let us know if there is interest in a OJ-enabled edition of Industrial Ethernet Book magazine.

Leopold Ploner

Source: Industrial Ethernet Book Issue 103 / 17
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