How Bluetooth Works

How Bluetooth Works

Bluetooth devices will normally operate at 2.4 GHZ
in the license free, globally available ISM radio
band. The advantage to this band includes worldwide
availability and compatibility. A disadvantage to
this however, is that the devices must share this
band with other RF emitters. This includes
automobile security systems, other wireless devices,
and other noise sources, such as microwaves.

To overcome this challenge, Bluetooth employs a
fast frequency hopping scheme and therefore uses
shorter packets than other standards within the
ISM band. This scheme helps to make Bluetooth
communication more robust and more secure.

Frequency hopping
Frequency hopping is basically jumping from frequency
to frequency within the ISM radio band. After a
bluetooth device sends or receives a packet, it
and the device (or devices) it's communicating with
hop to another frequency before the next packet is
sent. This scheme offers three advantages:
1. Allows Bluetooth devices to use the
entirety of the available ISM band, while never
transmitting from a fixed frequency for more than a
short period of time. This helps insure that
Bluetooth conforms to the ISM restrictions on the
transmission quantity per frequency.
2. Ensures that any interference won't
last long. Any packet that doesn't arrive safely
to its destination can be resent to the next
frequency.
3. Provides a base level of security as
it's very hard for an eavesdropping device to predict
which frequency the Bluetooth devices will use
next.

The connected devices however, must agree upon the
frequency they will use next. The specification
in Bluetooth ensures this in two ways. First, it
defines a master and slave type relationship between
bluetooth devices. Next, it specifies an algorithm
that uses device specific information when
calculating the frequency hop sequences.

A Bluetooth device that operates in master mode can
communicate with up to seven devices that are set in
slave mode. To each of the slaves, the master
Bluetooth device will send its own unique address
and the value of its own internal clock. The
information sent is then used to calculate the
frequency hop sequences.

Because the master device and each of the slave
devices use the same algorithm with the same initial
input, the connected devices will always arrive
together at the next frequency that they have agreed
upon.

As a replacement for cable technology, it's no
wonder that Bluetooth devices are usually battery
powered, such as wireless mice and battery powered
cell phones. To conserve the power, most devices
operate in low power. This helps to give Bluetooth
devices a range of around 5 - 10 meters.

This range is far enough for wireless communication
but close enough to avoid drawing too much power
from the power source of the device.






Bluetooth And Infared

With new electrical devices being produced every day,
the problem of connecting things is becoming more
and more complex in nature. The system that comprises
computers and other electronics makes use of varieties
of wires, cables, etc.

These parts will communicate through light beams,
lasers, radio signals, and infrared. The problem
however, is the devices and technology is often the
connection between each component. Therefore, most
electronic systems aren't used to their full extent
due to the problems and imperfections.

To help simplify things, a solution was created -
the solution of Bluetooth. Bluetooth is wireless
and automatic, offering users a variety of features
that have simplified the art of connection. Bluetooth
has revolutionized the standard methods of connecting
things to enabling almost anything to be connected
to a single system.

Aside from Bluetooth, there are other ways of
connecting wireless devices. One example of such
is the IR or infrared. Infrared allows low frequency
light waves to transmit signals to another component.
This technology is easy to create and the cost of
putting the IR device into a system is rather low.

Infrared technology is a one to one process. Due
to the limitation, you may only send signals from one
device to another, similar to a television set and
remote control. You can only transmit signals
between the two although not with a seperate system.

Aside from the fact that these two natures of
infrared are obstacles to acquiring results, these
same qualities have worked in advantage to the
connection. Infrared devices need to be lined up
directly, meaning too little interference can occur
between the transmitters and receivers.

The technology behind Bluetooth works by transmitting
signals through low frequency radio signals. The
path of communication is working on 2.45 GHz, which
is the same frequency band used in ISM devices.






Connecting Many With Bluetooth

Constantly evolving, the technology of Bluetooth
started off as a basic wireless connection standard
but has since then been adapted and proven with many
different uses and functions.

A good example is Bluetooth for cell phones. It
enables mobile users to connect to their hands free
headset without using wires. Bluetooth technology
will also allow mobile phone users to connect
with their hands free kit as well.

Another handy use of Bluetooth is file sharing. It
allows the sharing of files between two cell phones,
between a cell phone and computer, which makes the
sharing of files a snap. If you have a cell phone
and computer, you can easily transfer data between
the two.

Say for example you wanted to put an MP3 on your
phone from your computer you could do it easily
with Bluetooth. All you would need is a Bluetooth
adapter for your computer. It doesn't stop with the
swapping of files either,as you can use your computer
and phone to synchronise phone books, send SMS messages,
and much more.

Although Bluetooth may be dandy for cell phones,
it also comes in handy for the home office as well.
Utilizing Bluetooth is a great way to set up a
home office - two computers, a printer, and even a
scanner. They all can be connected using Bluetooth
technology with effective ranges of up to 10 meters.

The technology and devices of Bluetooth will be
around for years and years to come. As years go
by, Bluetooth will provide even better wireless
solutions for different applications. Even though
Bluetooth has a short range, it has that short
range for a reason. Bluetooth is easily the best
in wireless technology - which it continues to
prove time and time again.






Bluetooth Technical Operations

Bluetooth is a high speed, low powered wireless link
technology that's designed to connect phones or other
portable equipment together with little to no work
required by the user. Unlike infrared, Bluetooth
doesn't require line of site positioning to work.

Current prototype circuits are contained on a board
that is 0.9 cm square, with a much smaller circuit
board being developed.

When one Bluetooth device comes in contact with
another, they will automatically exchange addresses
and details of capability. Then, they can establish
a 1 MB link with security that they will use as
required. The protocols involved with handle both
data and voice, with a very flexible topography.

The technology achieves its goal by embedding tiny,
non expensive short range tranceivers into the
devices available today. The radio operates on the
2.45 GHz frequency band, and supports up to 721
KBps, along with three voice channels.

Each devices offers a unique 48 bit address from
the IEEE 802 standard, with the connections being
point to point or multipoint. The max range is
10 meters, although it can be extended to 100
meters by increasing the power. The devices are
also protected from radio interference by changing
their frequencies, also known as frequency hopping.

What's important, is the fact that Bluetooth
devices won't drain battery life. The specification
targets power consumption of the device, limiting
the drain on the battery. The radio chip will
consume only 0.3mA in stand by mode, which is less
than 5% of the power that standard phones use.

Bluetooth will also guarantee security at the bit
level. The authentification is controlled by the
user via a 128 bit key. The radio signals can
be coded with anything up to 128 bit. With the
frequency hopping, Bluetooth is already very
hard to listen into.

The baseband protocol is a combination of both
circuit and packet switches. Slots can be reserved
for synchronous packets as well. Each packet
will be transmitted in a different hop frequency.
Normally, a packet covers a single slot although
it can be extended to cover up to five slots.

Bluetooth can also support data channels of up to
three simultaneous voice channels. Therefore,
it's possible to transfer the data while you talk
at the same time. Each individual voice channel
will support 64 KB.

From a technical standpoint, Bluetooth is very
different indeed. It's the best wireless method
in the world, surpassing even infrared. For
communication on the go, Bluetooth is indeed
very hard to compete with.