Bluetooth at a Glance
Since its inception quite
some years ago, this technology developed by a spin-off company
from Cambridge University has become ubiquitous. Nowadays we
find it everywhere and just some examples are in mobile phones,
computers, laptops, computer mice, audio systems, car phones and
devices to control your home remotely.
That the technology was named Bluetooth is due to some tongue in
the cheek humour by its inventors. They named it Bluetooth after
a Danish King, "Harald Bluetooth Gormson", who ruled from around
958 to 970. He was famous for uniting Danish tribes into a
single nation under a banner of Christianity. The analogy is the
Bluetooth wireless technology unifies disparate devices into a
single network.
Bluetooth is simply a specification for a specific wireless
technology. This technology provides physically small and low
cost wireless connectivity between a variety of diverse devices
to create a personal area network.
The protocol uses
Frequency-hopping spread spectrum which means rapidly switching
between many frequency channels using a random sequence known by
both transmitter and receiver. This minimises interference,
provides security as the signals cannot easily be intercepted,
and the same frequency band can be shared with other radio
technologies.
The radio band used by Bluetooth is 2.4 GHz and there are two
versions of the protocol which provide different data transfer
rates. Version 1.x has a basic data transfer rate of 1Mbit/s and
Version 2.x has a transfer rate of 3Mbit/s. The range over which
devices can communicate depend on the Bluetooth Class. Class 1
devices have a range of 100 metres, Class 2 of 22 metres, and
Class 3 of 6 meters.
In practical terms, the Bluetooth specification is limited to
relatively low powered communications with moderate rates of
data transfer and it is not intended to compete with Wi-Fi
communication protocols such as 802.11x.
As Bluetooth developed over the years, new specifications were
created and each advance fixed problems with the previous
version. More features were added and performance was improved.
All specifications that followed Bluetooth 1.2 were made to be
backward compatible with 1.2. The most recent specification is
Bluetooth 4.0 which includes Classic Bluetooth, Bluetooth high speed and Bluetooth low energy protocols. In another article we explain the
differences between these Bluetooth versions and their
implications to current and future Bluetooth devices.
Author: Gary Shorthouse
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