What on earth is? Bluetooth

It might well sound like a contradiction in terms, but the wired world has no reverence for wires. No sooner had the global computing community got itself connected and conversing, than it wanted rid of the constricting cables. In almost every area of modern technology - be it mobile phones, mice or notebook computers - cords are being cut to allow us to work on the move.

Wires might be on the wane, but there's still every need for connections. Handheld computers need to exchange data with desktops, while notebook PC users will always want the ability to hook up to the company network in order to print documents and access shared files when back in the office.

That's where Bluetooth aims to help out. Named after an unsung Danish monarch of millennia past, the technology is a specification for low-cost, low-power, short-range radio links between electronic devices. The idea is that a Bluetooth-enabled unit can strike up data communications with other nearby machines in an instant, eliminating the cumbersome need for connecting cables.

Bluetooth's first claim to fame was successfully uniting two Baltic nations, eventually having them sing from the same religious songsheet - and there you have the rather tenuous reason for naming this modern communications technology after a long-forgotten 10th century king.

Amazingly, the organisation behind Bluetooth, the Special Interest Group, has so far managed to expand the details of the standard across two white papers, spanning some 1,536 pages in total. We'll try to be a little more concise.

The 2,000-plus members of the Special Interest Group, which include the likes of IBM and Intel, hope that Bluetooth will replace almost every cable in office environments, except for perhaps the power cords. Rather than being tied to the desktop, white-collar workers will simply plonk themselves and their computers down anywhere and work wirelessly with office printers, phone lines, fax machines and email systems.

In the wider world, hooking up to the internet when out and about will be made a whole lot easier through cordless connections. Notebook and handheld computers will be able to communicate with data-enabled mobile phones without them ever being pulled from pocket or bag.

THE SCIENCE

When Bluetooth devices communicate, the initiating machine assumes the role of 'master', negotiating data transfer paths between itself and up to seven other Bluetooth units, designated 'slaves'.

The technology enables any Bluetooth device to control another but the master-slave relationship is flexible. In simple exchanges, such as sending data between two notebook computers, the connection initiator becomes the master. Should another Bluetooth device attempt to communicate, it will automatically become a slave.

Some devices need to maintain master status at all times. For example, a Bluetooth office laser printer must remain as master to control the flow of prints from various PCs. For that reason, Bluetooth allows for status 'demotion'. In other words, a currently-employed master notebook sending a document to a shared printer using Bluetooth, will flit between master and slave ranks to satisfy both demands.

Bluetooth broadcasts between 2,400MHz and 2,485.5MHz using 79 distinct 1MHz frequencies. Transmitting devices randomly 'channel hop' 1,600 times a second in order to avoid contentions: if a channel is blocked, a clear one is found almost immediately.

THE BASICS

At the simplest level, Bluetooth is little more than a replacement for traditional cable connections. For example, rather than linking a PC and printer with a cord, information is sent using radio waves. The advantage is that Bluetooth is intended as a worldwide, multi-purpose standard, so your Bluetooth-enabled phone/printer/notebook/palmtop can establish connections with any other, without worrying about incompatible cables.

As radio waves travel in all directions and through all manner of obstacles, Bluetooth devices can communicate through walls, pockets and briefcases, which is ideal if you want your palmtop and phone to connect to the internet when you're stuck in a train carriage.

Bluetooth devices have a range of 10 metres and are able to transfer information at up to 1Mbit/s - about 20 times faster than a 56K modem.

In office environments, companies may choose to install repeaters that can increase the range.

With security in mind, Bluetooth gadgets and gizmos feature unique identifying codes, which can be used to prevent unauthorised use. A Bluetooth mobile phone, for instance, may be configured so that your palmtop computer - and yours alone - can dial up to the internet.

WHY YOU NEED TO KNOW ABOUT IT

For now, you can comfortably continue your computing capers without giving Bluetooth a second thought, as the technology has yet to take off in any significant way. Microsoft has recently made it clear that Bluetooth support will not be forthcoming in the latest version of its consumer operating system, Windows XP.

However, more devices will start to appear in the run-up to Christmas. The likes of Nokia and Ericsson are selling replacement battery modules that upgrade mobile phones to include Bluetooth communications. In combination with a Bluetooth-enabled computer, it's now possible to connect to the internet without a cable in sight and with mobile phone safely stowed in your pocket.

JARGONBUSTER

56K: The fastest standard for traditional modems. 56K means that a modem is capable of receiving up to 56,000 bits of computer data each second.
Mbit/s: Megabits per second. A measure of data-transfer speed. A megabit is one million bits.