A wireless connection lets you connect equipment without having to worry about plug or cables. But it can only work if your devices are fully compatible and are within range of each other.
This radio-based system provides communication over distances of up to around 30 feet (10 m). In theory, it runs at 1 Mbit/s, although in practice this falls to around 650 kbit/s, giving a transfer rate of between 50 and 80 kB/s.
Unlike a true wireless network, the Bluetooth system is designed to provide a simple two-way link between devices. However, the technology uses little energy, which is ideal for battery-powered devices such as personal organisers and mobile telephones. Apple have introduced their own wireless keyboard and mouse, both using Bluetooth technology.
If a Bluetooth device is made discoverable, it’s automatically connected to other devices within range. Up to 7 slave devices and one master device can work together to create a piconet, although up to 250 inactive slaves can also be present. Note that a master device in one piconet can also be a slave in another: piconets that overlap in this way are known as scatternets.
This radio-based system, also known as Bluetooth 2 and conforming to the IEEE 802.15 standard, offers an amazing data rate of 220 Mbit/s, although only over a range of about a metre. Such speed is made possible by using an incredible 7.5 GHz of radio spectrum, positioned between 3.1 GHz and 10.8 GHz. At the time of writing, no UWB products are available.
An infrared link, fitted in some portable computers and also on the ‘A’ version iMac, provides communication with suitable devices that are in close proximity. Sadly, there are very few products that use this kind of link. However, it can work with a personal organiser, such as a Palm, assuming both the hand-held device and the computer have the necessary software.
The infrared ports on Mac OS machines can use one of two protocols, as set by the Infrared control panel in the Classic Mac OS. The older protocol is IRTalk, which can be used to create an AppleTalk network between Mac OS computers and other devices. The alternative Infrared Data Association (IrDA) protocol, sometimes known as Infrared Technology, is also supported by non-Apple portable machines. The full-speed version of this runs at a transfer rate of 4 Mbit/s.
MacWorld magazine (UK), IDG Communications, 2002-3
©Ray White 2004.