Free clock democratises atomic accuracy

Researchers are developing a network of software-based clocks that could give data centres and networks the accuracy of an atomic clock for free.

The Robust Absolute and Difference clock - or RADclock for short - analyses information from multiple computers across the internet to construct a holistic view of time.

RADclock collects timing information from each machine's internal quartz clock and the time it takes for this information to be transmitted across the network.

It then compares all the information collected to determine a time that is most likely to be accurate, so machines are calibrated across the network.

Under good conditions, University of Melbourne engineer Julien Ridoux said RADclock could achieve microsecond accuracy - as good as that provided by a $50,000 atomic clock.

Most computers currently either rely on internal quartz clocks, or automatically synchronise with atomic clock servers like the NIST Internet Time Service via the internet.

But more accurate timing systems would be required to support network operations as they become faster and more complex, Ridoux said.

Ridoux described discussions with Google, ISPs, and some businesses in the finance industry for which accurate, network-wide timing information is important.

"With a super-fast network, tasks occur more frequently, and that requires computers to track the passing of time much more accurately," he said, noting that delays could introduce errors in video conversations, online games and power management.

"The techniques used in the past couple of decades are now not accurate enough to ensure the necessary coordination," he said.

The researchers are deploying test appliances in Australia and overseas with the National Measurement Institute (NMI), the Institute for a Broadband-Enabled Society (IBES) and the Australian Academic and Research Network (AARNet),

A minimum of three appliances will be deployed in any of AARNet's four domestic and two international points of presence.

"If it goes well, AARNet is a keen customer," the organisation's director of e-Research, Guido Aben, told iTnews.

Aben highlighted concerns with the Network Time Protocol (NTP) currently used by AARNet, noting that it was hard to detect errors and computers could potentially be manipulated into running on the wrong time.

Inaccurate time could, in turn, raise issues with error logging and security.

"[RADclock] could give us better, more robust timing information ... We believe that this is very valuable," Aben said.

A minimum of three devices would be required for RADclock, Ridoux said, but there is no upper limit: "Ultimately, we'd like to have everybody in the world using our software."

Distance, however, is an issue. So far, the researchers have only achieved microsecond accuracy for machines on a local area network.

Accuracy on the scale of 50 microseconds has been achieved for distances within 900 kilometres, and accuracy on the scale of 80 to 100 microseconds has been achieved within about 3,500 kilometres - the distance from Melbourne to Perth.

Because the system ultimately hinges on trusting that a majority of network machines are running on the right time, Ridoux acknowledged that the software-based system would never truly deliver the accuracy of a network of atomic clock-enabled computers.

"Basically there's a limit to what a computer is able to do; we will never beat an atomic clock," he said.

 "What we propose is not going to be a replacement for a GPS or atomic clock," he said. "We're propagating very good clock information over the network. We're trying to democratise access to very good time."