Category: Time Synchronisation

Keeping Track of Time Zones

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Despite the use of UTC (Coordinated Universal Time) as the world’s timescale, time zones, the regional areas with a uniform time, are still an important aspect of our daily lives. Time zones provide areas with a synchronised time that helps commerce, trade and society function, and allow all nations to enjoy noon at lunchtime. Most of us who have ever gone abroad are all aware of the differences in time zones and the need to reset our watches.

Time zones around the world

Keeping track of time zones can be really tricky. Different nations not only use different times but also use different adjustments for daylight saving, which can make keeping track of time zones difficult. Furthermore, nations occasionally move time zone, normally due to economic and trade reasons, which provides even more difficulties in keeping track of time zones.

You may think that modern computers can automatically account for time zones due to the settings in the clock program; however, most computer systems rely on a database, which is continuously updated, to provide accurate time zone information.

The Time Zone Database, sometimes called the Olson database after its long-time coordinator, Arthur David Olson, has recently moved home due to legal wrangling, which temporarily caused the database to cease functioning, causing untold problems for people needing accurate time zone information. Without the time zone database, time zones had to be calculated manually, for travelling, scheduling meetings and booking flights.

The Internet’s address system, ICANN (Internet Corporation for Assigned Names and Numbers) has taken over the database to provide stability, due to the reliance on the database by computer operating systems and other technologies; the database is used by a range of computer operating systems including Apple Inc’s Mac OS X, Oracle Corp, Unix and Linux, but not Microsoft Corp’s Windows.

The Time Zone Database provides a simple method of setting the time on a computer, enabling cities to be selected, with the database providing the right time. The database has all the necessary information, such as daylight saving times and the latest time zone movements, to provide accuracy and a reliable source of information.

Or course, a synchronised computer networks using NTP doesn’t require the Time Zone Database. Using the standard international timescale, UTC, NTP servers maintain the exact same time, no matter where the computer network is in the world, with the time zone information calculated as a difference to UTC.

 

 

Vote Called to End the Use of GMT and Scrapping the Leap Second

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International Telecommunications Union (ITU), based in Geneva, is voting in January to finally get rid of the leap second, effectively scrapping Greenwich Meantime.

 

Greenwich Mean Time may come to an end

UTC (Coordinated Universal Time) has been around since the 1970’s, and already effectively governs the world’s technologies by keeping computer networks synchronised by way of NTP time servers (Network Time Protocol), but it does have one flaw: UTC is too accurate, that is to say, UTC is governed by atomic clocks, not by the rotation of the Earth. While atomic clocks relay an accurate, unchanging form of chronology, the Earth’s rotation varies slightly from day-to-day, and in essence is slowing down by a second or two a year.

To prevent noon, when the sun is highest in the sky, from slowly getting later and later, Leap Seconds are added to UTC as a chronological fudge, ensuring that UTC matches GMT (governed by when the sun is directly above by the Greenwich Meridian Line, making it 12 noon).

The use of leap seconds is a subject of continuous debate. The ITU argue that with the development of satellite navigation systems, the internet, mobile phones and computer networks all reliant on a single, accurate form of time, a system of timekeeping needs to be precise as possible, and that leap seconds causes problems for modern technologies.

This against changing the Leap Second and in effect retaining GMT, suggest that without it, day would slowly creep into night, albeit in many thousands of years; however, the ITU suggest that large-scale changes could be made, perhaps every century or so.

If leap seconds are abandoned, it will effectively end Greenwich Meantime’s guardianship of the world’s time that has lasted over a century. Its function of signalling noon when the sun is above the meridian line started 127 years ago, when railways and telegraphs made a requirement for a standardised timescale.

If leap seconds are abolished, few of us will notice much difference, but it may make life easier for computer networks that synchronised by NTP time servers as Leap Second delivery can cause minor errors in very complicated systems. Google, for instance, recently revealed it had written a program to specifically deal with leap seconds in its data centres, effectively smearing the leap second throughout a day.

Google Finds Innovative Way to Avoid Leap Seconds

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Leap Seconds have been in use since the development of atomic clocks and the introduction of the global timescale UTC (Coordinated Universal Time). Leap Seconds prevent the actual time as told by atomic clocks and the physical time, governed by the sun being highest at noon, from drifting apart.

Since UTC began in the 1970’s when UTC was introduced, 24 Leap Seconds have been added. Leap seconds are a point of controversy, but without them, the day would slowly drift into night (albeit after many centuries); however, they do cause problems for some technologies.

NTP servers (Network Time Protocol) implement Leap Seconds by repeating the final second of the day when a Leap Second is introduced. While Leap Second introduction is a rare event, occurring only once or twice a year, for some complex systems that process thousands of events a second this repetition causes problems.

For search engine giants, Google, Leap Seconds can lead to their systems from working during this second, such as in 2005 when some of its clustered systems stopped accepting work. While this didn’t lead to their site from going down, Google wanted to address the problem to prevent any future problems caused by this chronological fudge.

Its solution was to write a program that essentially lied to their computer servers during the day of a Leap Second, making the systems believe the time was slightly ahead of what the NTP servers were telling it.

This gradual speeding up time meant that at the end of a day, when a Leap Second is added, Google’s timeservers do not have to repeat the extra second as the time on its servers would already be a second behind by that point.

Galleon GPS NTP server

Whilst Google’s solution to the Leap Second is ingenious, for most computer systems Leap Seconds cause no problems at all. With a computer network synchronised with an NTP server, Leap Seconds are adjusted automatically at the end of a day and occur only rarely, so most computer systems never notice this small hiccup in time.

 

British Atomic Clock Leads Race for Accuracy

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Researchers have discovered that the British atomic clock controlled by the UK’s National Physical Laboratory (NPL) is the most accurate in the world.

NPL’s CsF2 caesium fountain atomic clock is so accurate that it wouldn’t drift by a second in 138 million years, nearly twice as accurate as first thought.

Researchers have now discovered the clock is accurate to one part in 4,300,000,000,000,000 making it the most accurate atomic clock in the world.

The CsF2 clock uses the energy state of caesium atoms to keep time. With a frequency of 9,192,631,770 peaks and troughs every second, this resonance now governs the international standard for an official second.

The international standard of time—UTC—is governed by six atomic clocks, including the CsF2, two clocks in France, one in Germany and one in the USA, so this unexpected increase in accuracy means the global timescale is even more reliable than first thought.

UTC is essential for modern technologies, especially with so much global communication and trade being conducted across the internet, across borders, and across timezones.

UTC enables separate computer networks in different parts of the world to keep exactly the same time, and because of its importance accuracy and precision is essential, especially when you consider the types of transactions now conducted online, such as the buying of stocks and shares and global banking.

Receiving UTC requires the use of a time server and the protocol NTP (Network Time Protocol). Time servers receive a source of UTC direct from atomic clocks sources such as NPL, who broadcast a time signal over long wave radio, and the GPS network (GPS satellites all transmit atomic clock time signals, which is how satellite navigation systems calculate position by working out the difference in time between multiple GPS signals.)

NTP keeps all computers accurate to UTC by continuously checking each system clock and adjusting for any drift compared to the UTC time signal. By using an NTP time server, a network of computers is able to remain within a few milliseconds of UTC preventing any errors, ensuring security and providing an attestable source of accurate time.

 

Precise Time on the Markets

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The stock market has been in the news a lot lately. As global uncertainty about national debts rise, the markets are in flux, with prices changing incredibly quickly. On a trading floor, every second counts and precise time is essential for global buying and selling of commodities, bonds and shares.

NTS 6001 from Galleon Systems

The international stock exchanges such as the NASDAQ and London Stock Exchange all require accurate and precise time. With traders buying and selling shares for customers across the globe, a few seconds of inaccuracy could cost millions as share prices fluctuate.

NTP servers linked to atomic clock timing signals ensure that the stock exchange keeps an accurate and precise time. As computers across the globe all receive the stock prices, as and when they change, these two use NTP server systems to maintain time.

The global timescale UTC (Coordinated Universal Time) is used as the basis for atomic clock timing, so no matter where a trader is on the globe, the same timescale prevents confusion and errors when dealing with stocks and shares.

Because of the billions of pounds worth of stocks and shares that are bought and sold on trading floors every day, security is essential. NTP servers work externally to networks, getting their time from sources such as GPS (Global Positioning System) or radio signals put out by organisations like the National Physical Laboratory (NPL) or the National Institute for Standards and Time (NIST).

The stock exchanges can’t use a source of internet because of the risk this could pose. Hackers and malicious users could tamper with the time source, leading to mayhem and cost millions and perhaps billions if the wrong time was spread around the exchanges.

The precision of internet time is limited too. Latency over distance can create delays, which could lead to errors, and if the time source ever went down, the stock markets could hit trouble.

It is not only stock markets that need precise and accurate time, computer networks across the globe concerned about security use dedicated NTP servers like Galleon Systems’ NTS 6001. Providing accurate time from both GPS and radio signals from NPL and NIST, the NTS 6001 ensure accurate, precise and secure time every day of the year.

75 Years of the Speaking Clock

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Britain’s speaking clock celebrates its 75th birthday this week, with the service still providing the time to over 30 million callers a year.

The service, available by dialling 123 on any BT landline (British Telecom), began in 1936 when the General Post Office (GPO) controlled the telephone network. Back then, most people used mechanical clocks, which were prone to drift. Today, despite the prevalence of digital clocks, mobile phones, computers and a myriad number of other devices, the BT speaking clock still provides the time to 30 million callers a year, and other networks implement their own speaking clock systems.

Much of the speaking clock’s continuing success is perhaps down to the accuracy that it keeps. The modern speaking clock is accurate to five milliseconds (5/1000ths of a second), and kept precise by the atomic clock signals provided by NPL (National Physical Laboratory) and the GPS network.

But the announcer declaring the time ‘after the third stroke’ provides people with a human voice, something other time-telling methods don’t provide, and may have something to do with why so many people still use it.

Four people have had the honour of providing the voice for the speaking clock; the current voice of the BT clock is Sara Mendes da Costa, who has provided the voice since 2007.

Of course, many modern technologies require an accurate source of time. Computer networks that need to keep synchronised, for security reasons and to prevent of errors, require a source of atomic clock time.

Network time servers, commonly called NTP servers after Network Time Protocol that distributes the time across the computers on a network, use either GPS signals, which contain atomic clock time signals, or by radio signals broadcast by places like NPL and NIST (National Institute for Standards and Time) in the US.

Clock to Run for 10,000 Years

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The construction of clock, designed to tell the time for 10,000 years, is underway in Texas. The clock, when built, will stand over 60 metres tall and will have a clock face nearly three metres across.

Built by a non-profit organisation, the Long Now Foundation, the clock is being built so as to, not only still be standing in 10,000 years, but also still be telling the time.

Consisting of a 300kg gear wheel and a 140kg steel pendulum, the clock will tick every ten seconds and will feature a chime system that will allow 3.65 million unique chime variations—enough for 10,000 years of use.

Inspired by ancient engineering projects of the past, such as the Great Wall of China and the Pyramids—objects designed to last, the clock’s mechanism will feature state-of-the-art materials that don’t require lubrication of servicing.

However, being an mechanical clock, the Long Now Clock will not be very accurate and will require resetting to avoid drift otherwise the time in 10,000 years will not represent the time on Earth.

Even atomic clocks, the world’s most accurate clocks, require help in preventing drift, not because the clocks themselves drift—atomic clocks can remain accurate to a second for 100 million years, but the Earth’s rotation is slowing.

Every few years an extra second is added to a day. These Leap Seconds inserted on to UTC (Coordinated Universal Time) prevent the timescale and the movement of the Earth from drifting apart.

UTC is the global timescale that governs all modern technologies from satellite navigation systems, air traffic control and even computer networks.

While atomic clocks are expensive laboratory-based machines, receiving the time from an atomic clock is simple, requiring only a NTP time server (Network Time Protocol) that uses either GPs or radio frequencies to pick up time signals distributed by atomic clock sources. Installed on a network, and NTP time server can keep devices running to within a few milliseconds of each other and of UTC.

 

 

How Long is a Day?

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A day is something most of us take for granted, but the length of a day is not as simple as we may think.

A day, as most of us know, is the time it takes for the Earth to spin on its axis. Earth takes 24 hours to do one complete revolution, but other planets in our solar system have day lengths far different to ours.

Galleon NTS 6001

The largest planet, Jupiter, for instance, takes less than ten hours to spin a revolution making a Jovian day less than half of that of Earth, while a day on Venus is longer than its year with a Venusian day 224 Earth days.

And if you think of those plucky astronauts on the international Space Station, hurtling around the Earth at over 17,000 mph, a day for them is just 90 minutes long.

Of course, few of us will ever experience a day in space or on another planet, but the 24-hour day we take for granted is not as steadfast as you may think.

Several influences govern the revolution of the Earth, such as the movement of tidal forces and the effect of the Moon’s gravity. Millions of years ago, the Moon was much closer to Earth as it is now, which caused much higher tides, as a consequence the length of Earth’s day was shorter—just 22.5 hours during the time of the dinosaurs. And ever since the earth has been slowing.

When atomic clocks were first developed in the 1950’s, it was noticed that the length of a day varied. With the introduction of atomic time, and then Coordinated Universal Time (UTC), it became apparent that the length of a day was gradually lengthening. While this change is very minute, chorologists decided that to ensure equilibrium of UTC and the actual time on Earth—noon signifying when the sun is at its highest above the meridian—additional seconds needed to be added, once or twice a year.

So far, 24 of these ‘Leap Seconds’ have been since 1972 when UTC first became the international timescale.

Most technologies dependent on UTC use NTP servers like Galleon’s NTS 6001, which receives accurate atomic clock time from GPS satellites. With an NTP time server, automatic leap second calculations are done by the hardware ensuring all devices are kept accurate and precise to UTC.

 

Clocks that Changed Time

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If you’ve ever tried to keep track of time without a watch or clock, you’ll realise just how difficult it can be. Over a few hours, you may get to within half an hour of the right time, but precise time is very difficult to measure without some form of chronological device.

Before the use of clocks, keeping time was incredibly difficult, and even losing track of days of the years became easy to do unless you kept as daily tally. But the development of accurate timepieces took a long time, but several key steps in chronology evolved enabling closer and closer time measurements.

Today, with the benefit of atomic clocks, NTP servers and GPS clock systems, time can be monitored to within a billionth of a second (nanosecond), but this sort of accuracy has taken mankind thousands of years to accomplish.

 

Stonehenge–ancient timekeeping

Stonehenge

With no appointments to keep or a need to arrive at work on time, prehistoric man had little need for knowing the time of day. But when agriculture started, knowing when to plant crops became essential for survival. The first chronological devices such as Stonehenge are believed to have been built for such a purpose.

Identifying the longest and shortest days of the year (solstices) enabled early farmers to calculate when to plant their crops, and probably provided a lot of spiritual significance to such events.

Sundials

The provided the first attempts at keeping track of time throughout the day. Early man realised the sun moved across the sky at regular paths so they used it as a method of chronology. Sundials came in all sorts of guises, from obelisks that cast huge shadows to small ornamental sundials.

Mechanical Clock

The first true attempt at using mechanical clocks appeared in the thirteenth century. These used escapement mechanisms and weights to keep time, but the accuracy of these early clocks meant they’d lose over an hour a day.

Pendulum Clock

Clocks first became reliable and accurate when pendulums began appearing in the seventeenth century. While they would still drift, the swinging weight of pendulums meant that these clocks could keep track of first minutes, and then the seconds as engineering developed.

Electronic Clocks

Electronic clocks using quartz or other minerals enabled accuracy to parts of a second and enabled scaling down of accurate clocks to wristwatch size. While mechanical watches existed, they would drift too much and required constant winding. With electronic clocks, for the first time, true hassle free accuracy was achieved.

Atomic Clocks

Keeping time to thousands, millions and even billion parts of a second came when the first atomic clocks arrived in the 1950’s. Atomic clocks were even more accurate than the rotation of the Earth so Leap Seconds needed developing to make sure the global time based on atomic clocks, Coordinated Universal Time (UTC) matched the path of the sun across the sky.

 

Leap Second Argument Rumbles On

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The argument about the use of the Leap Second continues to rumble on with astronomers again calling for the abolition of this chronological ‘fudge.’

Galleon's NTS 6001 GPS

The Leap Second is added to Coordinated Universal Time to ensure the global time, coincides with the movement of the Earth. The problems occur because modern atomic clocks are far more precise than the rotation of the planet, which varies minutely in the length of a day, and is gradually slowing down, albeit minutely.

Because of the differences in time of the Earth’s spin and the true time told by atomic clocks, occasional seconds need adding to the global timescale UTC—Leap Seconds. However, for astronomers, leap seconds are a nuisance as they need to keep track of both the Earth’s spin—astronomical time—to keep their telescopes fixed on studied objects, and UTC, which they need as atomic clock source to work out the true astronomical time.

Next year, however, a group of astronomical scientists and engineers, plan to draw attention to the forced nature of Leap Seconds at the World Radiocommunication Conference. They say that as the drift caused by not including leap seconds would take such a long time—probably over a millennia, to have any visible effect on the day, with noon gradually shifting to afternoon, there is little need for Leap Seconds.

Whether Leap Seconds remain or not, getting an accurate source of UTC time is essential for many modern technologies. With a global economy and so much trade conducted online, over continents, ensuring a single time source prevents the problems different time-zones could cause.

Making sure everybody’s clock reads the same time is also important and with many technologies millisecond accuracy to UTC is vital—such as air traffic control and international stock markets.

NTP time servers such as Galleon’s NTS 6001 GPS, which can provide millisecond accuracy using the highly precise and secure GPS signal, enable technologies and computer networks to function in perfect synchronicity to UTC, securely and without error.