Chinese name
Bluetooth
Foreign name
Bluetooth
Interpretation
A short-range wireless communication technology
Data rate
1Mbps
Founder
Ericsson Corporation
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Bluetooth
The word "Bluetooth" (Bluetooth) is an Anglicized version of the Scandinavian word Bl?tand / Bl?tann (i.e., the Old Norse word blát?nn), which was used by a 10th-century King Harald Bluetooth, a nickname for a tenth-century king who united the feuding Danish tribes into a single kingdom and who, legend has it, introduced Christianity. The idea of naming Bluetooth after this was originally proposed in 1997 by Jim Kardach, who developed systems that allow cell phones to communicate with computers. He was inspired by The Long Ships, a historical novel about Norse pirates and King Harald Bluetooth written by Frans G. Bengtsson, which he was reading at the time, and meant that Bluetooth would also unify communication protocols as a global standard.
Bluetooth
Transmission Applications
Bluetooth Headset
Bluetooth's band is 2400-2483.5 MHz (including guard bands). This is the worldwide unlicensed (but not unregulated) 2.4 GHz short-range radio band in the Industrial, Scientific and Medical (ISM) band.
Bluetooth uses frequency hopping technology to split the transmitted data into packets, which are transmitted over each of 79 designated Bluetooth channels. Each channel has a bandwidth of 1 MHz. Bluetooth 4.0 uses 2 MHz spacing and can accommodate 40 channels. The first channel starts at 2402 MHz and continues every 1 MHz to 2480 MHz. with AdaptiveFrequency-Hopping (AFH), this is typically 1600 hops per second.
Initially, Gaussian frequency-shift keying (GFSK) modulation was the only available modulation scheme. However, Bluetooth 2.0+EDR enables the use of π/4-DQPSK and 8DPSK modulation in compatible devices. Devices running GFSK are said to be able to operate at Basic Rate (BR) with instantaneous rates of up to 1 Mbit/s. The term Enhanced Data Rate (EDR) is used to describe the π/4-DPSK and 8DPSK schemes, which can be up to 2 and 3 Mbit/s, respectively. In Bluetooth radio technology, the combination of the two modes (BR and EDR) is collectively referred to as "BR/EDR RF"
Bluetooth is a packet-based protocol with a master-slave architecture. A master device can communicate with up to seven slave devices in the same pico network. All devices *** share the master's clock. Packet switching is based on a base clock defined by the master that runs at 312.5?s intervals. Two clock cycles form a 625?s slot, and two time gaps form a 1250?s gap pair. In the simple case of single-slot packet sealing, the master device sends information in even-numbered slots and receives information in odd-numbered slots. The opposite is true for slave devices. The packet sealing capacity can be as long as 1, 3, or 5 time gaps, but in either case, the master device starts transmitting from the even-numbered slots, and the slave device starts transmitting from the odd-numbered slots.