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Brief Introduction About Bluetooth
Sep 03, 2018

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Bluetooth is a wireless communication technology that allows electronic devices

 

to communicate over small distances and, just as Wi-Fi, operates on the 2.4

 

GHz ISM frequency band. Despite operating on an open band, the   Bluetooth 

 

technology is regulated by the “Bluetooth Special Interest Group” (SIG) and

 

was standardized by IEEE as IEEE 802.15.1, even though it no longer maintains

 

the standard. Common examples of Bluetooth devices are Bluetooth

 

speaker,Bluetooth headsets, game controllers, wireless keyboards and mice 

 

and Bluetooth beacon.

 

Bluetooth uses 79 channels to transmit data, starting with the first channel at a

 

frequency of 2402 MHz and continuing up to the last one at a frequency of 2480 

 

MHz in 1 MHz increments.In order to avoid interference from other RF signals,a

 

technique known as frequency hopping where data is transmitted over one of

 

the available channels for a small period of time and resent over another 

 

channel in case of interference, is used in order to transmit data, Bluetooth

 

devices must first stablish a connection. One single device is capable of

 

connecting to up to 7 devices and communicating with each one of them 

 

simultaneously.This is done by using a connection model known 

 

as“master-slave”, in which the device that initiates the connection takes the  

 

role of master over the other devices. Whenever a master and a slave 

 

establish a connection, a bond is created, enabling them to transmit and

 

receive data.

 

Designed as a low-power technology, Bluetooth is meant to function on battery 

 

power devices over relatively short distances. Just as with Wi-Fi, the maximum 

 

distance over which a Bluetooth device can stablish a connection depends on

 

its output power, as well as other factors such as signal reflection caused by 

 

obstacles.Three different classes are used to classify Bluetooth devices 

 

according to their maximum output power and their corresponding maximum 

 

range. These can be seen in Table as below:

 

Class

Maximum Output Power

Range

1

20 db

Up to 100m

2

4 db

Up to 10m

3

0 db

0-10m