Wired and wonderful

Powerlines pose a threat to telecoms cables as an alternative method of internet access, writes CHRIS DANIELS.

The dream of the totally wired house with internet communications to every appliance, offering the ability to switch on the washing machine or oven from the PC at work, has been tripping off the tongues of tech-enthusiasts for years.

Telecoms companies have spent years and billions of dollars laying millions of kilometres of fibre-optic and copper cables, straining to get as many houses and buildings as possible plugged into their networks.

But a school of thought has emerged that the totally wired house does not need a fancy telecommunications cable coming into it, because the connection is already there - the humble electric power line.

Powerline communications is more than just a mad scientist's dream, it has been proven to work, allowing home PC users to plug their machine into the socket and head off into the world-wide web.

A special modem can be slotted straight into the three-point plug, sending and receiving data transmitted down the powerlines.

It means powerline companies are sitting on a gold mine they may never have thought of before - an unexpected and lucrative way to use all those wires criss-crossing the nation.

One of the big fans of powerline communications is John Rutherford, president of New Zealand telecoms company PacAmTel.

Powerline communications mean the dominance of Telecom New Zealand could be reduced in one fell swoop, says Mr Rutherford.

A company could start offering high-speed quality internet access without having to spend a cent on laying cables into everyone's home.

It is the ownership of the last few metres of phone line going into every domestic home that has allowed Telecom to stifle competition, he says, because any new competitor has to spend billions connecting every house.

His company holds patents for different types of communication technology, including systems for transmitting signals by satellite to neighbourhood transformers before being sent down the powerlines to homes.

Two research students, Scott Baugh and Maciej Matyjas, writing in the Powerline World website, describe a powerline-wired world where the phone line starts to seem old-fashioned.

"It could also be feasible to have an internet address for every plug in the house, through which you could e-mail, for example, fridge@home and study the picture relayed by the video camera to see what shopping you require, or you could remotely turn the lights off and the burglar alarm on using your own password," they say.

It is not clear how far down the track of powerline communications most New Zealand utility companies are. Rumours abound of covert units within each of the lines companies looking into how powerline communications would work.

Graeme Watson works for the nation's biggest powerlines group, United Networks, as general manager of asset strategy.

He sees a future for powerline internet communications in New Zealand, but is less enthusiastic than many. He says important economic and logistical conditions must be met before every home will be putting modems into three-point plug sockets.

Powerlines would not be used for all communications, just for taking a signal between a house and a neighbourhood transformer - the crucial last few hundred metres that cost a fortune for telecoms companies to install.

Mr Watson says economic factors would make a powerlines company think twice before offering internet access.

If the lines in a neighbourhood are mostly hanging from poles, it doesn't work so well, because the signals are subject to much more interference from radio waves.

A trial project in Manchester discovered that using the powerlines worked, but it also discovered the interference problems.

Lampposts acted as antennae, picking up users' downloads and rebroadcasting the data as radio waves - not the sort of thing likely to impress the authorities, or please users demanding even a modicum of privacy.

Another factor that needs to be considered before rushing out to buy shares in a lines company is the number of houses receiving power from the local transformers.

These footpath transformers are used to reduce the voltage from the 11,000 volts travelling through the main lines down to a more friendly 400 volts for the home.

Transformers are a problem if you want to use the powerline to communicate - it is very difficult and expensive to get the signal through the box.

This means that a powerline internet communication would travel by a normal route (along a fibre-optic link or copper cable) to the neighbourhood transformer. It would then travel along the powerlines to and from the home.

But the more homes that are connected to each transformer, the slower the connection would be.

On the flip side, if only one or two houses were linked to each transformer, it wouldn't make economic sense for the power company to plug it into a fibre-optic cable.

Mr Watson says this problem of an optimum number of connections to each local transformer means powerline communication is unlikely to be a saviour for internet users in rural areas.

When communicating using powerlines, a signal is sent at a different frequency from the 50 hertz that electricity comes along the line - in effect it is superimposed on the cable coming into the home.

"If you filter out the 50 hertz, then you're left with your communications signal basically," says Mr Watson.

"It's like having coarse gravel with sand in it - if you filter out the coarse stuff, the electricity, then all the sand left is your internet communications."

Are powerline communications going to seriously be part of internet communications in the future, or is it just a great idea that, while possible, may never be economic or practical?

"From an application and business point of view, if it is economically viable, well, we are definitely looking at it," says Mr Watson.

"But we certainly aren't investing a lot of time and money in the development of it.

"We have the numbers, we have the network, we are aware of the technology, but we're not going to go out there and invent the thing."