Super-accurate computer clock created

By Emma Young 14 July 2010
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Australian software that allows regular computers to keep time with incredible accuracy could improve everything from Skype to transport networks.

A FREE PIECE OF SOFTWARE that allows computers to keep phenomenally accurate time has been developed by researchers in Melbourne. The software, called RADclock, should improve everything from Skype conversations to the tracking of subway trains.

For computers to communicate effectively keeping accurate time is vital, say Julien Ridoux and Darryl Veitch of the University of Melbourne. “Every application or service that relies on computers collaborating implies that the computers are synchronised,” Julien says.

The problem is, while the clocks built into most computers keep time well, they’re not 100 per cent accurate. These clocks monitor how many times per second a quartz crystal inside the computer vibrates. But this ‘crystal frequency’ is a little different for every crystal, and changes all the time, due to variations in temperature, for example. “And that can make a big difference when errors accumulate,” he says.

Accurate replay

Skype software, for instance, has to estimate the delay in sending each packet of voice information sent over the internet to replay a voice accurately. With better clocks at both end, this can be done much more accurately, which will lead to better-quality conversations, the pair says.

“The more accurate, stable and reliable any clock, the more useful it is,” says Bruce Warrington, of the National Measurement Institute (NMI) in Melbourne. “This is true for computer clocks, and particularly true for computer networks.”

The RADclock software allows a computer to synchronise its clock with the nearest highly accurate time server. This might be the NMI server in Sydney, or, if a neighbour has already installed a RADclock, a computer down the street. And, for the purposes of keeping accurate time, the closer the computer the better.

Replacing GPS

The department of electrical engineering at the University of Melbourne is hosting the RADclock testbed, and already provides more than 20 time servers. The team is now deploying 10 more in Melbourne, Sydney and Adelaide, then they plan to expand to other capital cities and possibly also the United States. They’re working with the NMI and AARNet, Australia’s Academic and Research Network, to test the clock.

The RADclock won’t replace super-accurate computers that have an atomic clock attached to them, says Julien, but it should bring that kind of accuracy to regular computers. So far, he says, internet service providers, scientists and the banking and finance sector have all shown interest in the software.

Some other countries broadcast highly accurate time by radio, but researchers in Australia who need it usually use GPS, which can cost $10,000 to install. “RADclock holds the promise of highly accurate time running on off-the-shelf hardware rather than on lab machinery,” says Glen Turner, Regional Network Manager at AARNet.

At the moment, RADclock works only with open source software, such as Linux and FreeBSD, but a Windows version may be available in the future. Read more about the RADclock project here.