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Industrial Ethernet Book 103

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. 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. 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. Private Ethernet 50 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”. industrial ethernet book 11.2017 PHOTO: WIKIMEDIA The proud longships of king Harald and his Vikings The runic symbols Hagalaz and Berkanan form the Bluetooth logo.


Industrial Ethernet Book 103
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