Thursday, 10 October 2013

Bluetooth Operation




The networking standards of Bluetooth will transmit



data via low power radio frequency. Bluetooth



communicates on a 2.45 GHz frequency. This very



band of frequency has been set aside by international



agreement for the use of industrial and medical



devices.





Many devices that you already known and use take



advantage of this frequency band. Garage door



openers, baby monitors, and the next generation of



mobile phones all use this frequency within the ISM



band. Ensuring that Bluetooth and the other



devices don't interfere with each other is a crucial



part of the design process.





One of the ways Bluetooth will avoid interfering



with other electronic devices is by sending out



weak signals of around 1 mw. In comparison, even



the most powerful of cell phones can transmit a



signal of 3 watts.





The low power signals will limit the range of a



Bluetooth device to around 32 feet, which cut the



chances of interference between your computer and



other electronic devices. Even though it has low



power, Bluetooth doesn't require a line of sight



between the communicating devices. The walls in



your home won't stop the signal, making it great



for rooms throughout the house.





Bluetooth can connect 8 devices at the same time.



With each of those devices on the same radius,



you may think they would interfere with each



other, although it's very unlikely. Bluetooth



utilizes a technique known as low frequency



hopping, which makes it harder for more than



one device to transmit on the same frequency



at the same time.





With this technique, a device will use 79



individual, randomly chosen frequencies within



a designated range, which change from one another



on a regular basis.





In the case of Bluetooth, the transmitters will



change frequency 1,600 times or more every



second, meaning that more devices can make full



use of the radio spectrum. Since every



transmitter of Bluetooth will use spread spectrum



automatically, it's very unlikely that two



transmitters will be on the same frequency at the



exact same time.





When the Bluetooth devices come within close range



of each other, an electronic conversation will



occur to determine whether or not they have



data to share or whether one needs to take total



control. The user doesn't have any buttons to



press or commands to give - as the conversation



will occur automatically.





Once the conversation has occured, the devices



will form a network. Bluetooth devices will



create a PAN (Personal Area Network) or piconet



that may fill a room. Once the piconet has been



established, the devices will randomly hop in

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