Posts by: Stuart

The Atomic Clock History Accuracy and Uses

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Most people will have heard of atomic clocks, most people, probably without realising have even used them; however, I doubt many people reading this will have ever seen one. Atomic clocks are highly technical and complicated pieces of machinery. Relying on vacuums, super-coolants such as liquid nitrogen and even lasers, most atomic clocks are only found in laboratories such as NIST (National Institute for Standards and Time) in the US, or NPL (National Physical Laboratory) in the UK.

NPL's atomic clock

No other form of timekeeping is as accurate as an atomic clock. Atomic clocks form the basis of world’s global timescale UTC (Coordinated Universal Time). Even the length Earth’s spin requires manipulation by the addition of leap seconds to UTC to keep the day synchronised.

Atomic clocks work by using the oscillating changes of atoms during different energy states. Caesium is the preferred atom used in atomic clocks, which oscillates 9,192,631,770 times a second. This is a constant effect too, so much so that a second is now defined by this many oscillations of the caesium atom.

Louis Essen built the first accurate atomic clock in 1955 at the National Physical Laboratory in the UK, since then atomic clocks have become increasingly more accurate with modern atomic clocks able to maintain time for over a million years without ever losing a second.

In 1961, UTC became the world’s global timescale, and by 1967, the International System of Units adopted the Caesium frequency as the official second.

Since then, atomic clocks have become part of modern technology. Onboard every GPS satellite, atomic clocks beam time signals to Earth, enabling satellite navigation systems in car, boats and aeroplanes to judge their locations precisely.

UTC time is also essential for trade in the modern world. With computer networks speaking to each other across timezones, using atomic clocks as a reference prevents errors, ensures security and provides reliable data transfer.

Receiving a signal from an atomic clock for computer time synchronisation is incredibly easy. NTP time servers that receive the time signal from GPS satellites, or those broadcast on radio waves from places NPL and NIST, enable computer networks across the globe to keep secure and accurate time.

Summer Solstice The Longest Day

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June 21 marks the summer solstice for 2011. The summer solstice is when the Earth’s axis is most inclined to the sun, providing the most amount of sunshine for any day of the year. Often known as Midsummer’s day, marking the exact middle of the summer, periods of daylight get shorter following the solstice.

For the ancients, the summer solstice was an important event. Knowing when the shortest and longest days of the year were important to enable early agricultural civilisations to establish when to plant and harvest crops.

Indeed, the ancient monument of Stonehenge, in Salisbury, Great Britain, is thought to have been erected to calculate such events, and is still a major tourist attraction during the solstice when people travel from all over the country to celebrate the event at the ancient site.

Stonehenge is, therefore, one of the oldest forms of timekeeping on Earth, dating back to 3100BC. While nobody knows exactly how the monument was built, the giant stones were thought to have been transported from miles away—a mammoth task considering the wheel hadn’t even been invented back then.

The building of Stonehenge shows that timekeeping was as important to the ancients as it is to us today. The need for acknowledging when the solstice occurred is perhaps the earliest example of synchronisation.

Stonehenge probably used the setting and rising of the sun to tell the time. Sundials also used the sun to tell the time way before the invention of clocks, but we have come a long way from using such primitive methods in our timekeeping now.

Mechanical clocks came first, and then electronic clocks which were many times more accurate; however, when atomic clocks were developed in the 1950’s, timekeeping became so accurate that even the Earth’s rotation couldn’t keep up and an entirely new timescale, UTC (Coordinated Universal Time) was developed that accounted for discrepancies in the Earth’s spin by having leap seconds added.

Today, if you wish to synchronise to an atomic clock, you need to hook up to a NTP server which will receive an UTC time source from GPS or a radio signal and allow you to synchronise computer networks to maintain 100% accuracy and reliability.

Stonehenge–Ancient timekeeping

October Launch Date for Europes Version of GPS

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The launch date for the first Galileo satellites, the European version of the Global Positioning System (GPS), has been scheduled for mid October, say the European Space Agency (ESA).

Two Galileo in-orbit validation (IOV) satellites will be launched using a modified Russian Soyus rocket this October, marking a milestone in the Galileo project’s development.

Originally scheduled for August, the delayed October launch will lift off from ESA’s spaceport in French Guiana, South America, using the latest version of the Soyuz rocket—the world’s most reliable and most used rocket in history(Soyus was the rocket that propelled both Sputnik—the first orbital satellite—and Yuri Gargarin—the first man in orbit—into space).

Galileo, a joint European initiative, is set to rival the American controlled GPS, which is controlled by the United States military. With so many technologies reliant on satellite navigation and timing signals, Europe needs its own system in case the USA decides to switch off their civilian signal during times of emergency (war and terrorist attacks such as 9/11) leaving many technologies without the crucial GPS signal.

Currently GPS not only controls the words transportation syste3ms with shipping, airliners and motorists increasingly becoming reliant on it, but GPS also provides timing signals to technologies such as NTP servers, ensuring accurate and precise time.

And the Galileo system will be good for current GPS users too, as it will be interoperable and, therefore, will increase accuracy of the 30-year-old GPS network, which is in need of upgrade.

Currently, a prototype Galileo satellite, GIOVE-B, is in orbit and has been functioning perfectly for the last three years. Onboard the satellite, as with all global navigation satellite system (GNSS) including GPS, is an atomic clock, which is used to transmit a timing signal that Earth-based navigation systems can use to triangulate accurate positioning (by using multiple satellite signals).

The atomic clock aboard GIOVE-B is currently the most accurate atomic clock in orbit, and with similar technology intended for all Galileo satellite, this is the reason why the European system will be more accurate than GPS.

These atomic clock systems are also used by NTP servers, to receive an accurate and precise form of time, which many technologies are dependent on to ensure synchronicity and accuracy, including most of the world’s computer networks.

Keeping the World Synchronised A Brief History

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Global time synchronisation may seem like a modern need, we do after all live in a global economy. With the internet, global financial markets and computer networks separated by oceans and continents—keeping everybody running in synchronisation is a crucial aspect of the  modern world.

Yet, a need for global synchronicity began a lot earlier than the computer age. International standardisation of weights and measures began after the French revolution when the decimal system was introduced and a platinum rod and weight representing the metre and the kilogram were installed in the Archives de la République in Paris.

Paris eventually became the central head of the International System of Units, which was fine for weights and measures, as representatives from different countries could visit the vaults to calibrate their own base measurements; however, when it came to standardising time, with the increased use of transatlantic travel following the steamer, and then the aeroplane, things became tricky.

Back then, the only clocks were mechanical and pendulum driven. Not only would the base clock that was situated in Paris drift on a daily basis, but any traveller from the other side of the world wanting to synchronise to it, would have to visit Paris, check the time on the vault’s clock, and then carry their own clock back across the Atlantic—inevitable arriving with a clock that had drifted perhaps several minutes by the time the clock arrived back.

With the invention of the electronic clock, the aeroplane and transatlantic telephones, things became easier; however, even electronic clocks can drift several seconds in a day so the situation wasn’t perfect.

These days, thanks to the invention of the atomic clock, the SI standard of time (UTC: Coordinated Universal Time) has so little drift even a 100,000 years wouldn’t see the clock lose a second. And synchronising to UTC couldn’t be simpler no matter where you are in the world—thanks to NTP (Network Time Protocol) and NTP servers.

Now using GPS signals or transmissions put out by organisations like NIST (National Institute for Standards and Time-WVBB broadcast) and NPL (National Physical Laboratory—MSF broadcast) and using NTP servers, ensuring you are synchronised to UTC is simple.

NTP servers like Galleon’s NTS 6001 GPS receive a atomic clock time signal and distributes it around a network keeping every device to within a few milliseconds of UTC.

 

Galleon's NTS 6001 GPS Time Server

The Fragility of Time Japanese Earthquake Shortens the Day

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The recent and tragic earthquake that has left so much devastation in Japan has also highlighted an interesting aspect about the measurement of time and the rotation of the Earth.

So powerful was the 9.0 magnitude earthquake, it actually shifted Earth axis by 165mm (6½ inches) according to NASA.

The quake, one of the most powerful felt on Erath over the last millennia, altered the distribution of the planet’s mass, causing the Earth to rotate on its axis that little bit faster and therefore, shortening the length of every day that will follow.

Fortunately, this change is so minute it is not noticeable in our day to day activities as the Earth slowed by less than a couple of microseconds (just over a millionth of a second), and it isn’t unusual for natural events to slow down the speed of the Earth’s rotation.

In fact, since the development of the atomic clock in the 1950’s, it has been realised the Earth’s rotation is never continual and in fact has been increasing very slightly, most probably for billions of years.

These changes in the Earth’s rotation, and the length of a day, are caused by the effects of the moving oceans, wind and the gravitational pull of the moon. Indeed, it has been estimated that before humans arrived on Earth, the length of a day during the Jurassic period (40-100 million years ago) the length of a day was only 22.5 hours.

These natural changes to the Earth’s rotation and the length of a day, are only noticeable to us thanks to the precise nature of atomic clocks which have to account for these changes to ensure that the global timescale UTC (Coordinated Universal Time) doesn’t drift away from mean solar time (in other words noon needs to remain when the sun is highest during the day).

To achieve this, extra seconds are occasionally added onto UTC. These extra seconds are known as leap seconds and over thirty have been added to UTC since the 1970’s.

Many modern computer networks and technologies rely on UTC to keep devices synchronised, usually by receiving a time signal via a dedicated NTP time server (Network Time Protocol).

NTP time servers are designed to accommodate these leap seconds, enabling computer systems and technologies to remain accurate, precise and synchronised.

Keeping the World Ticking Over The Global Timekeepers

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When we want to know the time it is very simple to look at a clock, watch or one of the myriad devices that display the time such as our mobile phones or computers. But when it comes to setting the time, we rely on the internet, speaking clock or somebody else watch; however, how do we know these clocks are right, and who is it that ensures that time is accurate at all?

Traditionally we have based time on Earth in relation to the rotation of the planet—24 hours in a day, and each hour split into minutes and seconds. But, when atomic clocks were developed in the 1950’s it soon became apparent that the Earth was not a reliable chronometer and that the length of a day varies.

In the modern world, with global communications and technologies such as GPS and the internet, accurate time is highly important so ensuring that there is a timescale that is kept truly accurate is important, but who is it that controls global time, and how accurate is it, really?

Global time is known as UTC—coordinated Universal Time. It is based on the time told by atomic clocks but makes allowances for the inaccuracy of the Earth’s spin by having occasional leap seconds added to UTC to ensure we don’t get into a position where time drifts and ends up having no relation to the daylight or night time (so midnight is always at day and noon is in the day).

UTC is governed by a constellation of scientists and atomic clocks all across the globe. This is done for political reasons so no one country has complete control over the global timescale. In the USA, the National Institute for Standards and Time (NIST), helps govern UTC and broadcast a UTC time signal from Fort Collins in Colorado.

While in the UK, the National Physical Laboratory (NPL) does the same thing and transmits their UTC signal from Cumbria, England. Other physics labs across the world have similar signals and it is these laboratories that ensure UTC is always accurate.

For modern technologies and computer networks, these UTC transmissions enable computer systems across the globe to be synchronised together. The software NTP (Network Time Protocol) is used to distribute these time signals to each machine, ensuring perfect synchronicity, while NTP time servers can receive the radio signals broadcast by the physics laboratories.

Mechanisms of Time History of Chronological Devices

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Nearly every device seems to have a clock attached to it these days. Computers, mobile phones and all the other gadgets we use are all good sources of time. Ensuring that no matter where you are a clock is never that far away – but it wasn’t always this way.

Clock making, in Europe, started around the fourteenth century when the first simple mechanical clocks were developed. These early devices were not very accurate, losing perhaps up to half an hour a day, but with the development of pendulums these devices became increasingly more accurate.

However, the first mechanic al clocks were not the first mechanical devices that could tell and predict time. Indeed, it seems Europeans were over fifteen hundred years late with their development of gears, cogs and mechanical clocks, as the ancients had long ago got there first.

Early in the twentieth century a brass machine was discovered in a shipwreck (Antikythera wreck) off Greece, which was a device as complex as any clock made in Europe up in the mediaeval period. While the Antikythera mechanism is not strictly a clock – it was designed to predict the orbit of planets and seasons, solar eclipses and even the ancient Olympic Games – but is just as precise and complicated as Swiss clocks manufactured in Europe in the nineteenth century.

While Europeans had to relearn the manufacture of such precise machines, clock making has moved on dramatically since then. In the last hundred or so years we have seen the emergence of electronic clocks, using crystals such as quartz to keep time, to the emergence of atomic clocks that use the resonance of atoms.

Atomic clocks are so accurate they won’t drift by even a second in a hundred thousand years which is phenomenal when you consider that even quartz digital clocks will drift several seconds n a day.

While few people will have ever seen an atomic clock as they are bulky and complicated devices that require teams of people to keep them operational, they still govern our lives.

Much of the technologies we are familiar with such as the internet and mobile phone networks, are all governed by atomic clocks. NTP time servers (Network Time Protocol) are used to receive atomic clock signals often broadcast by large physics laboratories or from the GPS (Global Positioning System) satellite signals.

NTP servers then distribute the time around a computer network adjusting the system clocks on individual machines to ensure they are accurate. Typically, a network of hundreds and even thousands of machines can be kept synchronised together to an atomic clock time source using a single NTP time server, and keep them accurate to within a few milliseconds of each other (few thousandths of a second).

UTC One Time to Rule Them All

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In a global economy time has become a more crucial than ever before. As people across the globe, communicate, conference and buy and sell from each other, being aware of the each other’s time is vital for conducting business successfully.

And with the internet, global communication and time awareness are even more important as computers require a source of time for nearly all their applications and processes. The difficulty with computer communication, however, is that if different machines are running different times, all sorts of errors can occur. Data can get lost, errors fail to log; the system can become unsecure, unstable and unreliable.

Time synchronisation for computer networks communicating with each other is, therefore, essential – but how is it achieved when different networks are in different time-zones?

The answer lies with Universal Coordinated Time (UTC) an international time-zones developed in the 1970’2 that is based on accurate atomic clocks.  UTC is set the same the world over, with no accounting for time-zones so the time on a network in the UK – will be identical to the network time in the USA.

UTC time on a computer network is also kept synchronised through the use of NTP (Network Time Protocol) and an NTP server.  NTP ensures all devices on a networked system have exactly the right time as different computer clocks will drift at varying rates – even if the machines are identical.

While UTC makes no accounting for time-zones system clocks can still be set to the local time-zone but the applications and functions of a computer will use UTC.

UTC time is delivered to computer networks through a variety of sources: radio signals, the GPS signal, or across the internet (although the accuracy of internet time is debatable). Most computer networks have a NTP time server somewhere in their server room which will receive the time signal and distribute it through the network ensuring all machines are within a few milliseconds of UTC and that the time on your network corresponds to every other UTC network on the globe.

Computer Time Synchronisation The Basics

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With so much automated in the modern world and with computer networks running everything from finance to health services, keeping, storing and transferring information needs to be secure, accurate and reliable.

The time is crucial for computer systems to ensure this. Timestamps are the only information computers have to assess if a task has been completed, is due, or that information has been successfully received, sent or stored. One of the most common causes of computer errors comes from inadequate synchronisation of timings.

All computer networks need to be synchronised, and not just all the devices on a network, either. With so much global communication these days, all computer networks across the globe need to be synchronised together, otherwise when they communicate errors may occur, data can get lost, and it can pave the way for security problems as time discrepancies can be used by malicious users and software.

But how do computers synchronise together? Well, it is made possible by to innovations. The first is the international timescale, UTC (Coordinated Universal Time), kept true by atomic clocks and the same the world over, regardless of time-zones. The second, NTP (Network Time Protocol) is a computer program designed to keep PCs synchronised together.

Both NTP and UTC operate in tandem. The computer time server (NTP server) receives a UTC time source, either from radio, GPS (Global Positioning System) or the internet (although an insecure method of receiving UTC and not recommended).

NTP then distributes this time around a network, checking the time on each device at periodic intervals and adjusts them for any drift in time. Most computer networks that utilise NTP time servers in this way have each machine on the network within milliseconds of UTC time, enabling accurate and precise global communication.

NTP time servers are the only secure and accurate method of computer network synchronisation and should be used by any computer system that requires reliability, accuracy and security.

From Pennies to NTP Servers the Intricacies of Keeping Time

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Keeping accurate time is an essential aspect of our day to day lives. Nearly everything we do is reliant on time from getting up for work in the morning to arranging meetings, nights out or just when it’s time for dinner.

Most of us carry some kind of clock or watch with us but these timepieces are prone to drift which is why most people regularly use another clock of device to set their time too.

In London, by far the most common timepiece that people use to set their watches too is Big Ben. This world famous clock can be seen for miles, which is why so many Londoners use it to ensure their watches and clocks are accurate – but have you ever wondered how Big Ben keeps itself accurate?

Well the unlikely truth lies in a pile of old coins. Big Ben’s clock mechanism uses a pendulum but for fine tuning and ensuring accuracy a small pile of gold coins resting on the top of the pendulum.  If just one coin is removed then the clock’s speed will change by nearly half a second

Ensuring accuracy on a computer network is far less archaic. All computer networks need to run accurate and synchronised time as computers too are completely reliant on knowing the time.

Fortunately, NTP time servers are designed to accurately and reliably keep entire computer networks synchronised. NTP (Network Time Protocol) is a software protocol designed to keep networks accurate and it works by using a single time source that it uses to correct drift on

Most network operators synchronise their computers to a form of UTC time (Coordinated Universal Time) as this is governed by atomic clocks (highly accurate timepieces that never drift – not for several thousand years, anyway).

A source of atomic clock time can be received by a NTP server by using either GPS satellite (Global Positioning System) signals or radio frequencies broadcast by national physics laboratories.

NTP servers ensure that computer networks all across the globe are synchronised, accurate and reliable.