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