China move could call time on GMT

PUBLISHED : Friday, 30 December, 2011, 12:00am
UPDATED : Friday, 30 December, 2011, 12:00am


The hour has come. China has decided to call a truce with the United States in the fight for time.

Next month, a Chinese government delegation heads to the International Telecommunication Union (ITU) in Geneva to cast its vote and its influence in the 193-member organisation - on a US proposal to amend the global standard of timekeeping.

The US wants to get rid of time standards based on the earth's rotation, a somewhat erratic system that underpins Greenwich Mean Time and Co-ordinated Universal Time.

Instead, Washington wants the world to stick to International Atomic Time (TAI), which is based on around 400 atomic clocks ticking away in some 70 national institutes of measurement, observatories and other institutions located in 48 nations.

The change is supported by most developed countries - except the UK, the historical home of GMT - because of TAI's immediate technical benefits in an age of satellite navigation and air-traffic control systems. But it will need a big majority to gain acceptance at next month's meeting of the ITU, a specialist agency of the United Nations.

Beijing has long opposed changing the system, perceiving the US proposal as an attempt to thwart China's growing influence at the ITU, and one with serious economic consequences: upgrading software and devices alone would cost hundreds of millions of dollars.

US technology, such as its satellite-based global positioning system, would continue to dominate the global market.

But Beijing may now support the change, said Liu Changhong, senior engineer at the National Time Service Centre and Beijing's spokesman on the issue. Advancements like the Beidou satellite navigation system have shown Beijing the drawbacks of the current system.

'A few years ago we could not understand some technical complaints from the US and took them as a plot against China because we had not encountered those problems,' Liu said. 'Now we do. Our delegation will attend the meeting with an open mind. If most countries want the change, we will vote for it.'

The decision made in Geneva may be the most important since 1961, when the world adopted Co-ordinated Universal Time (UTC), which was itself based on Greenwich Mean Time - the cornerstone of international timekeeping since 1884.

Since then, time has ticked along with the earth's orbit around the sun. However, friction from the ocean's tides affects its rotation, creating a gap between UTC and TAI. A later convention was adopted to synchronise the two by adding a 'leap second' whenever the difference became greater than 0.9 seconds.

Dr Wayne Hanson, chairman of the US delegation to the ITU, says adjusting for a leap second is causing problems for American hardware and technicians. Some time-sensitive equipment, such as internet servers, have difficulty coping and some system maintainers have not followed the official procedure.

'Some systems were intentionally interrupted several hours before and after the event to prevent operational mishaps,' Hanson, a time-signal engineering specialist at the National Institute of Standards and Technology's physics laboratory, wrote to the ITU last year.

Because of the leap second, even experts made mistakes when using the global positioning system for timekeeping, he added.

China has found itself in a similar situation since the deployment of its Beidou navigation system, Liu said.

'The leap-second operation has made ground devices more difficult to maintain,' Liu said. 'Dropping the leap second would give everyone a break, especially our consumers. We sweat each time a leap second operation is called, for fear that the equipment might go wrong.'

But China is not without its concerns about the US proposal. The new standard, which would go into effect in 2017, would force Beijing to recall many sensitive devices already in use, for fear of manipulation or malfunctioning. 'That means lots of work and costs amounting to billions of yuan,' Liu said.

A spokeswoman for the Beidou system said they would support the new stand of the Chinese delegation to the ITU and would release technical details of how any proposed change would affect Beidou.

Not all mainland researchers agree with the government's change of stance. Professor Gao Yuping, a researcher at the National Time Service Centre, said he prefers the current system because it honours tradition.

'I don't think we should get rid of the sun in our definition of a day simply for some technological convenience,' Gao said. 'I am a human before I am a scientist, and I feel uncomfortable surrendering everything to atomic clocks.'


Seconds that International Atomic Time has gained on Co-ordinated Universal Time since their first synchronisation in 1958