Archive for December, 2008

NTP Server News – Calls to Abolish the Leap Second

Be careful when counting down to the New Year this week as an extra second is to be added to the last minute of 2008. Leap Seconds are added to UTC (Coordinated Universal Time) the time used by most NTP Server systems and has been going on since its inception in 1972 with a total of 33 seconds having already been added to UTC since then.

However there are calls to make this leap second the last ever. The International Telecommunications Union (ITU) is proposing to abolish them in favour of adding a “leap hour” every 600 years.

They claim that the Leap Second creates confusion and can cause software crashes. They cite 1996 as an example, when computers at Associated Press Radio crashed causing them to broadcast the wrong programmes, and a 2003 bug caused some GPS units to show the time as 62:30.

However, there is stiff opposition to abolishing the Leap Second, among them astronomers, Robert Massey of the Royal Astronomical Society told the London Times: “It would be a change with profound cultural implications.  We’d be decoupling our clocks from what the Sun is telling us.”

The implications for astronomers would require expensive changes to the software of astronomical telescopes and it would become almost impossible for sailors to navigate by sextant. It would also mean the Britain would lose its role as the World’s timekeepers as the Greenwich Meridian (the position of the sun at midday) would gradually move south to France until the proposed leap hour would return it to its original position after 600 years.


Useful NTP server related resources – The home for the NTP Project who provides support and additional development resources for the Official Reference Implementation of NTP.

NTP Project support pages

THE NTP pool – list of public servers

NPL – The National Physical Laboratory in the UK who control the MSF radio signal.

The University of Delaware and David Mills’ information page, Professor Mills is the original inventor and developer of NTP

David Mills’ list of Public NTP Time Servers a list of public NTP servers

National Institute of Standards and Technology (NIST) who operate the USA’s WWVB radio signal

Europe’s largest supplier of NTP server related products.

Galleon UK – NTP server products for the UK – one of the largest time and frequency suppliers in the United States

NTP – Wikipedia article on NTP

NTP server checker – free tool to ensure time server accuracy

NTP server – Instruments of Precision

Time synchronisation in the modern age is highly precise. Modern atomic clocks can keep time so accurately that in 100 million years these timekeeping devices will not lose even a second.

Bit is this sort of accuracy necessary in the modern world? How important can a second possibly be, after all, a second has always been seen as one of the smallest units of time.

However, when you consider modern technology such as the satellite navigation then a second suddenly becomes a huge gulf in time. Modern satellite navigation devices work by calculating distance by using the time form the atomic clocks on GPS (Global Positioning System) satellites.

However, when you consider that the speed of light is close to 300, 000 km a second then you can understand that if a GPS clock is a second out then your navigation could be inaccurate by hundreds of thousands of kilometres.

The same is true for modern computer networks. Computers can process thousands of transactions a second so when it comes to global network communication a second can be a huge amount of time.

That is why modern NTP server’s, responsible for synchronising networks offer precision to the millisecond, ensuring that network across the globe are within a hare’s breath of each other.

MSF signal interruption – Notice from the National Physical Laboratory

For users of MSF time server or other NTP related devices:

Notice of Interruption MSF 60 kHz Time and Frequency Signal – NPL
The MSF 60 kHz time and frequency signal broadcast from Anthorn Radio Station will be shut down over the period:

11 December 2008 – from 10:00 UTC to 14:00 UTC

The interruption to the transmission is required to allow scheduled maintenance work to be carried out in safety.

If you require any additional information, please contact NPL

Or alternatively please see the NPL time website.