Beaming Video at Speed of Light
By Kim Griggs
The free-space optics system developed by New Zealand company Power Beat International works by modulating a beam of visible light -- the part of the electromagnetic spectrum that can be seen by humans -- to carry a digital or analog signal.
"When a video recorder is looking at something, it is reading the voltages that are being transferred from light onto a surface of photo cells. We take all of those voltage changes and use them to modulate our light," said Peter Witehira, managing director of Power Beat.
Free-space optics has had uses elsewhere: After the Sept. 11 terrorist attacks, Merrill Lynch used an FSOlink provided by Terabeam to connect two offices 2.6 kilometers apart. AirFiber helped transmit images of the 2002 MTV European Music Awards from the stadium to the telecommunication provider's headquarters using a 1.65-kilometer laser connection.
One of the technology's key benefits is the amount of data that can be transmitted over short distances: The Merrill Lynch link transmitted data at a rate of 1 Gbps, nearly 1,000 times faster than a typical broadband connection. The lack of bureaucracy is another plus -- there are no spectrum licenses to buy. There are also no cables to lay, making installation cheap and simple relative to the potential connection speeds.
"Say you want to get it across the motorway, even if it's only a hundred meters, digging a trench under a motorway to put a fiber-optic cable in costs you nearly a million dollars, but the cost of deploying this thing (FSO) is next to nothing," said John Harvey, professor of physics at the University of Auckland. "Some one rigs it up on a power pole and it's done."
On the other hand, bad weather, or anything that might block the light's path, can cause slowdowns or power failures.
"There are a number of problems," said Australia independent telecommunications analyst Paul Budde. "The technology is definitely not stable, so it is very difficult to do it in a commercial sort of environment. It needs continuous fine-tuning."
But by using light-emitting diodes as the light source, instead of lasers, Power Beat says the system, dubbed Megamantis, is easier to align. Light concentrators at the receiving end also mean that less accurate alignment is required than what's required with lasers. And by using LEDs, which are cheap, Power Beat aims to keep the cost of Megamantis low and the speed high.
"With one LED today it is possible to get up to 400 Mbps in modulated speed," Witehira says.
And Witehira says his company's system isn't affected by rain, and can be adjusted for fog.
"You can overcome that by having a combination of two different wavelengths at the extremes you can get with light -- far infrared and near ultraviolet, which is a deep blue. If you have both of those running at once, you don't have a problem with fog. You may still have a problem with whiteout," he said.
Getting around corners, Witehira said, is just a matter of bouncing light off glass or by making a network of lights. And the line-of-sight possibilities are growing: Eighteen months ago the company's technology could send data just 3 meters; now it can span 4 kilometers. The maximum line of sight at the moment is probably 11 kilometers, the company reckons.
The only time during the Hamilton demonstration that the picture went fuzzy was when one of the Power Beat team members put his hand across the light source -- and even that, Witehira pointed out, has a plus side. "There is no stray radiation here," he says. "We can send more data and you can put your hand right in front of it."
The University of Auckland's Harvey said FSO technology works well in certain niches -- such as on distributed university or hospital campuses.
"If you are just ringing your mother-in-law, that probably doesn't matter. But if you are dialing 111 (emergency), it probably does," Harvey said. "What I think people would accept with free-space optical is a high-speed link, which is available 97 percent of the time, and still have your ordinary telephone."
Power Beat plans to promote Megamantis in its first incarnation for closed-circuit television and for data links between buildings. The company has a test system working at the local airport, relaying an image of the airport parking lot back to the Power Beat office across the road. In the Australian state of Queensland, the Peanut Company of Australia has used a Megamantis test link to transmit data from one building to another at its Kingaroy site.
Witehira sees possibilities for his company's system as moving beyond a niche: "Much of the free-space optics out there have been concentrating on data transfer point-to-point, but we can spread it across the whole city. We could actually have a 360-degree array around the city. That then means that, for very low cost, you can establish your own community television broadcast system.
"Ultimately this technology will make it possible for households in small communities to reach an enormous amount of information, at the speed of light, of course."
The crowding of the radio spectrum may leave a light-based technology as the only option, said Megamantis investor Ross Palmer, an Australian businessman. "There may be a day when light is the only thing that works."
Budde was more reserved about FSO's potential.
"Something might happen technology-wise that stabilizes the technology and therefore makes it more commercial. That is quite possible," he said. "But at the moment the scientists have to go a very, very long way to make it work."
Power Beat's Witehira shakes off such skepticism.
At the Hamilton demonstration, he urged the guests -- who included New Zealand's Prime Minister Helen Clark and the Maori Queen Te Arikinui Dame Te Atairangikaahu -- to "remember this night."
"This is the beginning of the changing of the course of history in free-space communications," Witehira said.
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