Bluetooth

Bluetooth
Bluetooth is a standard of communication allowing the bidirectional exchange of data very short distance by using radio waves UHF on a frequency band of 2,4 GHz. His objective is to simplify the connections between the electronic devices by suppressing wired connections. it can replace for example wires between computers, tablets, mobile phones between them or with printers, scanners, keyboards, mouse, video game controllers, mobile phones, free hands microphone or earphones systems and kits, car radios, digital cameras, readers of bar codes and interactive advertising borders.

The first devices using the 4.0 version appeared in the beginning of the year 2010.

Bluetooth network
A piconet is a little network which is created instantaneously and automaticaly when several bluetooth devices are in range.A piconet is organised in a star topology: there is a "master" and several "slave".

A ""master" can administer up to: The communication between a "master" and a "slave" is direct. The "slaves" cannot communicate between each other.
 * 7 "slaves" in a "active" state
 * 255 "slaves" in a "parked" mode

All the "slaves" of the piconet are synchronized on the clock of the "master". It's the "master" who determines the jump frequency of the entire piconet.

The different piconets can thus be interconnected, using the "slaves" wich are shared between several piconets. The network so formed is called a scatternet.

Advantages
In the versions marketed in 2015 (4.0 and 4.1), widely used, essentially in mobile devices as mobile phones, the Bluetooth connection presents the following characteristics: Accordingly, he is present on devices often working on battery, wishing to exchange a small quantity of data on a short distance:
 * low energy consomption
 * verry low range ( a few dozen of meters)
 * low data rate
 * cheap and low profile
 * cellphones
 * mobile computers
 * diverse peripherals, as keyboards
 * specialised peripherals, as electrocardiograms