Bluetooth

From Computing and Software Wiki

The Bluetooth logo merges the Nordic runes analogous to the modern Latin H and B: (haglaz) and (berkanan) forming a bind rune

The Bluetooth was developed in 1994 by Sven Mattisson and Jaap Haartsen, working for Ericsson Mobile Platforms in Lund, Sweden.

Bluetooth was named after a late tenth century king, Harald Bluetooth, King of Denmark and Norway. He is known for his unification of previously warring tribes from Denmark (including Scania, present-day Sweden) and Norway. Bluetooth likewise was intended to unify different technologies, such as computers and mobile phones.

Bluetooth offers services that enable the connection of devices and the exchange of a variety of data classes between these devices. Bluetooth wireless technology is a short-range communications system mean to substitute the wires connecting electronic devices. It is a standard that wirelessly connects mobile phones, portable computers, cars, stereo headsets, MP3 players, and more. The key features of Bluetooth wireless technology are robustness, low power, and low cost. The specifications were formalized on May 20, 1998, by the Bluetooth Special Interest Group (SIG).

The Technology

Band of Emission

The Bluetooth RF (Radio Frequency) operates in the unlicensed ISM 5Industrial, Scientific and Medical) band at 2.4GHz to 2.485GHz using 79 channels at 1MHz intervals to give a good interference immunity. The system utilizes a frequency hop transceiver, full-duplex signal at a nominal rate of 1600 hops/sec, to reduce interferences, and provides many FHSS (Frequency Hop Spread Spectrum) carriers. By detecting and avoiding the frequencies the others devices are using, the AFH (Adaptive Frequency Hoping) runs through the available frequency. This adaptive hopping allows for more efficient transmission within the spectrum, providing users with greater performance even if using other technologies along with Bluetooth technology

Range

The operating range depends on the device class:

- Class 1 radios

• used primarily in industrial use cases
• have a range of 100 meters or 300 feet
• Maximum Permitted Power: 100mW/20dBm

- Class 2 radios

• most commonly found in mobile devices
• have a range of 10 meters or 33 feet
• Maximum Permitted Power: 2.5mW/4dBm

- Class 3 radios

• have a range of up to 1 meter or 3 feet
• Maximum Permitted Power: 1mW/0dBm

--Morsall 15:18, 12 April 2009 (EDT)