Home automation has been slow to take off in Australia. Typically, if you want to control your lights at the touch of a button, you've got two options: throw large amounts of money at a Custom Install solution or plump for a cheap unreliable X-10 approach.
For those of you unfamiliar with X-10, the technology uses a combination of powerline signalling and wireless RF communications to link devices together in the home. For example, with an LM12U lamp module plugged into one wall socket (with a lamp plugged into said module), and a TM13U transceiver plugged into another, you can remotely turn the lamp on and off, even dim it, using an RF keypad.
This is only the start. Add a computer interface and PC software to this loose X-10 network and you can program the lamp to switch on/off at certain times (i.e. while you're out). Install a passive IR sensor, and you can then instruct the lamp to switch on whenever the sensor detects any movement. Up to 256 different modules – including cameras, appliance switches and wall dimmers – can be connected together. X-10 sounds like the perfect DIY home automation system.
The problem with X-10
But X-10 isn't perfect. It's an old technology, first introduced in the US in 1975. Not only is it subject to interference from other appliances plugged into your mains wiring, but X-10 signals themselves can often interfere with each other.
Then there's the slow response time (it can sometimes a second or two from button-press to light switching on) and the fact that there's no way to show whether a device has received a command or not – if an ‘on' command is sent, X-10 then assumes that the device it sent to is ‘on', regardless of whether the signal got there.
It's why Z-Wave technology is aiming to replace it. Z-Wave is based on an open RF standard between devices that has been developed by the US company Zen-sys. Unlike X-10, which principally uses the home's mains wiring to route its data signals, Z-Wave devices use a sub-gigahertz RF mesh network to communicate with each other.
This infrastructure means that each device on the mesh network acts as a node. If one device is out of range of another, signals can be sent via other nearby devices. Unlike X-10, a device transmitting signals (i.e. a computer sending an ‘on' command to a light switch), will also request confirmation of its transmission from the receiving device, avoiding lost signals. If the sending device doesn't receive confirmation of a signal, it resends the signal until it gets one.
"With a Z-Wave network," says the Z-Wave Alliance, "if the signal is blocked the first time the signal will notify the controller that it did not complete the connection and the network will immediately seek an alternative path. It may go to a hallway light, then the thermostat, then a dimmer switch in the dining room… It will try as many times as is necessary, or until all possibilities are exhausted. Once the operation is complete, you receive an indication on the controller telling you the action has occurred."
Should we believe the hype?
On paper, at least, Z-Wave has the potential to be the revolution in home automation that we've been waiting for. The mesh network is reliable and offers a two-way communication system to surpass X-10's one-way data traffic. The bandwidth is also much lower than X-10 (between 9 and 40Kbps) minimising interference with other electrical and electronic devices.
