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device is set by its class specification.
There are four Bluetooth classes,
ranging from 100mW for a Class 1
device down to 0.5mW for a Class 4
device. The corresponding typical range
varies from ~100m for a Class 1 device
down to ~0.5m for a Class 4.
CORE SPECIFICATIONS
Bluetooth specifications are created
by an organisation known as the
Bluetooth Special Interest Group (SIG).
SIG was formed by five companies
in 1998, and it now has more than
30,000 members.
In 1999, Version 1.0 of the Bluetooth
Core Specification was released by
SIG and gained the ‘Best of Show
Technology’ award at COMDEX
that year.
It operated at a maximum throughput
of ~700kbps using frequency shift
keying modulation, and the range was
up to 100m.
To put this into perspective, a typical
digital photo taken at that time would
have been about 70kB in size, so it
would take ~10 seconds to send it over
a Bluetooth link. Today, photos can be
10MB and more, and Bluetooth has had
to evolve to remain useful.
By 2001, laptop, PC card, keyboard,
mouse, printer, headset and car
hands-free mobile implementations
had appeared. By 2002, the number
of Bluetooth qualified products had
exceeded 500.
In 2004, SIG adopted Core
Specification Version 2.0 Enhanced
Data Rate (EDR) with a link speed of
3Mbps, and Bluetooth had an installed
base of 250 million devices.
By 2009, SIG had 12,000 members,
the Bluetooth installed base had
reached two billion devices and SIG
had adopted Version 3 of the Core
Specification with a link speed of
24Mbps.
In conjunction, SIG adopted low-
energy wireless technology and
implemented it the following year in
Version 4 of the Core Specification.
Known as Bluetooth Smart (or BLE –
Bluetooth Low Energy), it was intended
to offer a similar range as Bluetooth
Classic but with much reduced power
consumption and somewhat lower
application throughput speed. And all
at a much lower cost.
Typical applications include sport
and fitness devices, location beacons,
security and home entertainment
equipment and smart phones. Most
major mobile phone operating systems
support Bluetooth Smart.
Bluetooth Smart has been aimed
specifically at the IoT – a proposed
development in which new devices such
as sensors and other common objects
have network connectivity, allowing
them to send and receive data. The IoT
will depend on cloud-based applications
to collect and process data from the
sensors and other devices and send it
to the end user.
Bluetooth Smart is not backwards
compatible with Classic Bluetooth.
However, support for both can co-exist
in the one device, and such dual-
mode devices have been marketed as
Bluetooth Smart Ready.
Because Bluetooth Smart operates
on the same ISM band as Classic
Bluetooth, dual-mode devices can share
an antenna.
One of the first products to
implement Bluetooth Smart technology
was the iPhone 4S (2011). Unlike Classic
Bluetooth, Bluetooth Smart does not
support voice capability, so dual-mode
capability is a must for applications
when power consumption is important
(e.g. devices such as mobile phones).
Finally, in June 2016, SIG announced
the next release of the Core
Specification Version 5, due later this
year or early in 2017. It promises to
substantially increase range and speed,
and vastly increase broadcasting
messaging capability – a feature not
well used to date.
FUNCTIONALITY AND APPLICATIONS
Bluetooth Smart Ready low-power
devices have their functionality defined
in SIG Bluetooth profiles.
A profile is a specification for how a
particular type of device should work
in a particular application, and a device
may contain more than one profile.
The profiles are intended to be
Standards, and manufacturers of
devices must comply to ensure that
their devices will function correctly.
Groups of profiles are classified
according to their application. For
example, sets of profiles exist for
health care, sport and fitness, proximity
sensing, alerts and time, generic
sensors, etc.
Bluetooth capability in one form
or another is already in billions of
electronic devices in everyday use.
The new Bluetooth Core Specification
Version 5 is aimed at meeting the future
needs of devices designed for the IoT.
George Georgevits, BE (Hons),
manages his engineering consultancy
Power and Digital Instruments. PDI was
established in 1980 and specialises in
lab and field testing, troubleshooting of
electrical systems and components, and
consulting engineering. Contact PDI on
+61 2 9411 4442.
Bluetooth has become a popular form of smart
wireless technology for fast short-range data
communication between devices.