Harald Blåtand, or Bluetooth, was king of Denmark from about 940 until about 986. He is remembered for converting his country to Christianity and also for giving his name to the technology that enables wireless communication between devices.
The man behind this technology was Sven Mattisson in Lund. He graduated as an engineer in 1979 and began to work at the Department of Applied Electronics in the Faculty of Engineering at Lund University.
His potential was noted and he was sent as an exchange student to the California Institute of Technology, where the subject of his PhD thesis was formulated: how to develop a circuit simulator that would reproduce analog behavior in an integrated circuit. Mattisson was awarded his PhD in 1986 and became involved in a wide range of tasks – such as categorizing transistors and developing programs that could generate circuit diagrams.
In 1995 he went to work for Ericsson Mobile Communications. “They had no explicit plan about what to do with me,” Mattisson says. “I was placed in a forward-looking project together with a Dutchman called Jaap Haartsen. We were to work on a concept involving short-range radio links with low output. The point was that mobile phones with this kind of radio link would be able to communicate with each other without having to be connected by cables.
Initially these were called MC Links, which stood for Multi-Communicator Links.
“It did not take long before we realized that Ericsson should not be developing this technology on its own.”
TOOK THE BAIT
In 1997, Intel took the bait and its head of technological development, Jim Kardach, became Mattisson’s enthusiastic colleague. One of their insights was that MC Links could be used not only to link mobile phones but lots of other kinds of devices as well.
“And the technology would be most useful as an open standard in the unrestricted frequency range of 2.45 GHz. We invited in Nokia, IBM and Toshiba, and set up a joint development group for the project,” Mattisson recounts.
The technology was launched in May 1998, under the name of Bluetooth, to great expectations.
“We underestimated how long it would take for the technology to be ready for mass production. And people were not impressed when we said that the data transfer rate for the user could reach 721 kbps. Some people laughed at us and we were told that Wi-Fi could offer a lot more.
Then we found out that the Wi-Fi people were talking about the maximum speed and this only applied between antennas in one direction, and only when conditions were ideal. We were too honest, quite simply.”
Bluetooth did have a future. Ten years later there are three output specifications for the technology and data transfer rates exceed 20 Mbps. There are also plans for coordinating a really broad bandwidth in which Bluetooth could attain speeds of several hundred Mbps.
Bluetooth exploits a frequency-hopping technology with 1,600 hops per second, to reduce interference and fading, and therefore permits different classes of radio. The class used in mobile phones usually offers a range of just over 10 meters, while the modules in PCs work over 100 meters or more. Almost 3,000 companies have adopted the standard.
Bluetooth works by equipping every unit (telephone, PC, printer, keyboard, headset, microphone and so on) with a Bluetooth chip and an antenna. The chip combines a transmitter and receiver and listens for signals from other Bluetooth chips while transmitting signals that indicate its identity. As soon as two chips make contact with each other, they begin negotiations to establish a suitable link.
Bluetooth is based on about ten patents, most of them owned by Ericsson. “These patents are important if we are to be able to safeguard the open standard and stop others from messing it up,” Mattisson says.
Where did the name of Bluetooth come from?
HERO’S FATHER-IN-LAW
“At the end of the summer of 1997, Jim Kardach and I were having a beer together in Toronto. We had been taking part in a competition about a new radio system with our project, but our presentation was not successful and did not give us much of a chance of winning.
I had given Jim the English translation of Frans G. Bengtsson’s The Long Ships and he was fascinated by the man described as its hero’s father-in-law, Harald Blåtand,” Mattisson recalls.
“So we began to talk about Bluetooth instead of MC Link. We had engaged consultants to dream up a suitable name but nobody had come up with anything as good as Bluetooth.”
Then Kardach happened to come across the Jellinge stone, a runestone in Denmark that tells of Harald Blåtand. He took the liberty of copying a picture from the Jellinge stone on to two new stones with a few minor adjustments. The stone you can see here has a picture of Harald Blåtand with a laptop in one hand and a mobile telephone in the other.
“Then someone told Jim that the picture on the Jellinge stone is probably Jesus. I think that information came as something of a shock to him,” Mattisson says.
The stone can still be seen outside Ericsson’s development unit in Lund.
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