Beginners start here: Bluetooth basics

Sean McNamara
31 January, 2008
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There’s one technology included in all new Macs (and many not-so-new ones) which is overlooked by many Mac users — Bluetooth.

Although Bluetooth is technically a networking protocol, I find it easier to think of it as being like "wireless USB" — a short-range, low(ish) bandwidth connection method perfectly suited for connecting your computer to small portable devices such as mice, keyboards, PDAs, phones and printers (amongst many others).

Invented in Lund, Sweden, it was named after the nickname of Harald I of Denmark, who unified warring tribes in Denmark and Norway, just as the modern Bluetooth is meant to unify different "tribes" of technological devices, and its logo is a combination of the Germanic rune characters equivalent to H and B (Harald Bluetooth).

Data rates vary, depending on the version of the specification of the transceiver built into devices, with most consumer devices these days having the v2.x version (which operates at 3 megabits per second). The wireless range depends on the power output of the transceiver, with most general devices having a range of approximately 10 metres.

For Macs without built-in Bluetooth which have a USB port, it is possible to use a USB dongle ($50-$70) to give Bluetooth functionality to the Mac — no extra software is required for Macs running Mac OS X v10.2 or later. Once plugged in, the dongle gives exactly the same functionality as the built-in version.

Macs can use Bluetooth for many different uses — I use Bluetooth to synchronise my phone, computer and PDA wirelessly (not needing to plug in makes me much more likely to do the synchronisation), as well as to remote control my computer from my phone or PDA (using a great piece of shareware called Salling Clicker).

I also use Bluetooth to send small files to and from my phone and PDA, ready for sending on to Macs at other locations (I can even browse my phone’s file heirarchy from my Mac — especially useful for files I’ve saved in the wrong location on my phone).

The most useful thing I do with Bluetooth, however, is to make my phone into a wireless 3G modem for internet access while I’m out and about — my computer doesn’t even have to be physically close to my phone (as long as it’s in the same room) and I don’t need a separate USB 3G modem to plug in.

Making it work. Bluetooth has two concepts which are integral to inter-device communication: discoverability and pairing. If a device is discoverable, it means other devices within range can see it and communicate with it. Having a device always discoverable is a potential security risk, as any other Bluetooth device within range can see the device as being available for connections, and compromised devices may try to send on their malicious payload to such devices (files can be sent to a discoverable device from another device with which it hasn’t paired). Given the ultra-portability of most Bluetooth devices like phones and PDAs, it’s generally a good idea to turn off discoverability when not pairing to new devices.

Each device has its own procedure to turning discoverability on and off. If my phone is set to discoverable, I reject any incoming file which I didn’t explicitly send to my phone myself, including promotional pictures sent via Bluetooth, which seems to be a popular marketing tool in shopping centres these days.

Pairing is an established trusted relationship between two devices. To establish a pairing relationship, at least one of the devices needs to be discoverable when pairing so the other can see it to establish the connection. Often when pairing, one or both of the devices will ask you to enter a passkey. Sometimes the passkey is generated by the initiating device, sometimes the initating device will ask you to create one — either way, both devices need to know the passkey, and you’ll often be prompted to enter the passkey on the second device.

Mac OS X’s Bluetooth pairing procedure generates the passkey for you, displays it in big type, and asks you to enter it on the other device. Some devices, such as mice, don’t have anything to enter the passkey on, so will generally have an empty passkey which is automatically detected and entered for you.

Once pairing relationships are established, Bluetooth is a very convenient way to use your external devices — it’s certainly freed me up in many ways both when travelling (fewer cables to pack, more convenient internet connection) and at the home office (fewer cables on my desk, and when I’m on the lounge I can connect to devices on my desk without trippable cables).

If you have a Bluetooth-capable Mac (or buy a Bluetooth dongle) and a Bluetooth device or two, I encourage you to explore what uses you might be able to put it to.

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