Category: atomic clocks

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

Using NIST Time Servers

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The National Institute for Standards and Technology (NIST) is one of the world’s leading atomic clock laboratories, and is the leading American time authority. Part of a constellation of national physics laboratories, NIST help ensure the worlds atomic clock time standard UTC (Coordinated Universal Time) is kept accurate and is available for the American people to use as a time standard.

All sorts of technologies rely on UTC time. All the machines on a computer network are usually synchronised to source of UTC, while technologies such as ATM’s, closed-circuit television (CCTV) and alarm systems require a source of NIST time to prevent errors.

Part of what NIST does is to ensure that sources of UTC time are readily available for the technologies to utilise, and NIST offer several means of receiving their time standard.

The Internet

The internet is the easiest method of receiving NIST time and in most Windows based operating systems, the NIST time standard address is already included in the time and date settings, allowing easy synchronisation. If it isn’t, to synchronise to NIST you simply need to double click on the system clock (bottom right hand corner) and enter the NIST server name and address. A full list of NIST Internet servers, here:

The Internet, however, is not a particularly secure location to receive a source of NIST time. Any Internet time source will require and open port in the firewall (UDP port 123) for the time signal to get through. Obviously, any gap in a firewall can lead to security issues, so fortunately NIST provide another method of receiving their time.

NTP Time Servers

NIST, from their transmitter in Colorado, broadcasts a time signal that all of North America can receive. The signal, generated and kept true by NIST atomic clocks, is highly accurate, reliable and secure, received externally to the firewall by using a WWVB timeserver (WWVB is call sign for the NIST time signal).

Once received, the protocol NTP (Network Time Protocol) will use the NIST time code and distribute it around the network and will ensure each device keeps true to it, continually making adjustments to cope with drift.

WWVB NTP time servers are accurate, secure and reliable and a must-have for anybody serious about security and accuracy who wants to receive a source of NIST time.

Japan Loses Atomic Clock Signal after Quakes

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Having suffered earthquakes, a catastrophic tsunami, and a nuclear accident, Japan has had a terrible start to the year. Now, weeks after these terrible incidents, Japan is recovering, rebuilding their damaged infrastructure and trying to contain the emergencies at their stricken nuclear power plants.

But to add insult t injury, many of the Japanese technologies that rely on an accurate atomic clock signals are starting to drift, leading to problems with synchronisation. Like in the UK, Japan’s National Institute of Information, Communications and Technology broadcast an atomic clock time standard by radio signal.

Japan has two signals, but many Japanese NTP servers rely on the signal broadcast from mount Otakadoya, which is located 16 kilometres from the stricken Daiichi power station in Fukushima, and falls within the 20 km exclusion zone imposed when the plant started leaking.

The consequence is that technicians have been unable to attend to the time signal. According to the National Institute of Information, Communications, and Technology, which usually transmits the 40-kilohertz signal, broadcasts ceased a day after the massive Tohoku earthquake struck the region on 11 March. Officials at the institute said they have no idea when service might resume.

Radio signals that broadcast time standards can be susceptible to problems of this nature. These signals often experience outages for repair and maintenance, and the signals can be prone to interference.

As more and more technologies, rely on atomic clock timing, including most computer networks, this susceptibility can cause a lot of apprehension amongst technology managers and network administrators.

Fortunately, a less vulnerable system of receiving time standards is available that is just as accurate and is based on atomic clock time—GPS.

The Global Positioning System, commonly used for satellite navigation, contains atomic clock time information used to calculate positioning. These time signals are available everywhere on the planet with a view of the sky, and as it is space-based, the GPS signal is not susceptible to outages and incidents such as in Fukushima.

 

The Truth about Time

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As a manufacturer of NTP time servers, synchronizing computer networks and keeping them accurate to within a few milliseconds of international UTC time (Coordinated Universal Time), we often think we can keep pretty good track of time.

Time, however, is quit elusive and is not the fixed entity we often assume it is, indeed time, and the time told on Earth is not constant and is affected by all sorts of things.

Since Einstein’s famous equation, E=MC2 it has been acknowledged that time is not constant, and that the only constant in the universe is the maximum velocity of light. Time, as Einstein discovered, is affected by gravity, making the time on Earth run slightly slower than time in deep space, likewise, on planetary bodies with a larger mass than Earth, time runs even slower.

Time slows down when you approach very fast speeds too. The property of time, known as time dilation, was discovered by Einstein and means that at close to the speed of light, time almost stands still (and makes interstellar travel a possibility for science fiction writers).

Generally, living on Earth, these differences in time are not felt, and indeed the slowing of time caused by Earth’s gravity is so minute, highly precise atomic clocks are required to measure it.

However, the time we use to govern our lives is also affected by other factors. Since humans first evolved, we have been used to a day lasting just over 24 hours.  However, the length of a day on Earth is not fixed, and has been changing for the last few billion years.

Each day on Earth differs from the previous to the next one. Often these differences are minute, but year on year, the changes add up as the affect of the moon’s gravity and tidal forces act as a brake on the Earth’s spin.

To cope with this, the global timescale UTC (Coordinated Universal Time) has to be adjusted to prevent the day from drifting out of sync (and we end up with noon at night and midnight during the day—although at the current slowing of the Earth, this would take many thousands of years).

The adjustment in our time is known as leap seconds which are added either once or twice a year to UTC. Anybody using a NTP time server (Network Time Protocol) to synchronise their computer network too, needn’t worry, however, as NTP servers will automatically account for these changes.

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.

Importance of Atomic Clock Time Sources for Technology

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Timekeeping and accuracy is important in the running of our day-to-day lives. We need to know what time events are occurring to ensure we don’t miss them, we also need to have a source of accurate time to prevent us from being late; and computers and other technology are just as reliant on the tine as we are.

For many computers and technical systems, the time in the form of a timestamp is the only tangible thing a machine has to identify when events should occur, and in what order. Without a timestamp a computer is unable to perform any task—even saving data is impossible without the machine knowing what time it is.

Because of this reliance on time, all computer systems have in-built clocks on their circuit boards. Commonly these are quartz based oscillators, similar to the electronic clocks used in digital wrist watches.

The problem with these system clocks is that they are not very accurate. Sure, for telling the time for human purposes they are precise enough; however, machines quite often require a higher level of accuracy, especially when devices are synchronised.

For computer networks, synchronisation is crucial as different machines telling different times could lead to errors and failure of the network to perform even simple tasks. The difficult with network synchronisation is that the system clocks used by computers to keep time can drift. And when different clocks drift by differing amounts, a network can soon fall into disarray as different machines keep different times.

For this reason, these system clocks are not relied on to provide synchronisation. Instead, a far more accurate type of clock is used: the atomic clock.

Atomic clocks don’t drift (at least not by more than a second in a million years) and so are ideal to synchronise computer networks too. Most computers use the software protocol NTP (Network Time Protocol) which uses a single atomic clock time source, either from across the internet, or more securely, externally via GPS or radio signals, in which it synchronises every machine on a network to.

Because NTP ensures each device is kept accurate to this source time and ignores the unreliable system clocks, the entire network can be kept synchronised to with each machine within fractions of a second of each other.

Keeping a Windows 7 Network Secure, Reliable and Accurate

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Many modern computer networks are now running Microsoft’s latest operating system Window 7, which has many new and improved features including the ability to synchronise time.

When a Windows 7 machine is booted up, unlike previous incarnations of Windows, the operating system automatically attempts to synchronise to a time server across the internet to ensure the network is running accurate time. However, while this facility is often useful for residential users, for business networks it can cause many problems.

Firstly, to allow this synchronisation process to happen, the company firewall must have an open port (UDP 123) to allow the regular time transference. This can cause security issues as malicious users and bots can take advantage of the open port to penetrate into the company network.

Secondly, while the internet time servers are often quite accurate, this can often depend on your distance from the host, and any latency caused by network or internet connection can further cause inaccuracies meaning that you system can often be more than several seconds away from the preferred UTC time (Coordinated Universal Time).

Finally, as internet time sources are stratum 2 devices, that is they are servers that do not receive a first-hand time code, but instead receive a second hand source of time from a stratum 1 device (dedicated NTP time server – Network Time Protocol) which also can lead to inaccuracy – these stratum 2 connections can also be very busy preventing your network from accessing the time for prolonged periods risking drifting.

To ensure accurate, reliable and secure time for a Windows 7 network, there is really no substitute than to use your own stratum 1 NTP time server. These are readily available from many sources and are not very expensive but the peace of mind they provide is invaluable.

Stratum 1 NTP time servers receive a secure time signal direct from an atomic clock source. The time signal is external to the network so there is no danger of it being hijacked or any need to have open ports in the firewall.

Furthermore, as the time signals come from a direct atomic clock source they are very accurate and don’t suffer any latency problems. The signals used can be either through GPS (Global Positioning System satellites’ have onboard atomic clocks) or from radio transmissions broadcast by national physics laboratories such as NIST in the USA (broadcast from Colorado), NPL in the UK (transmitted form Cumbria) or their German equivalent (from Frankfurt).

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).

How Atomic Clocks Control our Transport Systems

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Getting from A to B has been a primary concern for societies ever since the first roads were built. Whether it is horseback, carriage, train, car or plane – transportation is what enables societies to grow, prosper and trade.

In today’s world, our transportation systems are highly complex due to the sheer numbers of people who are all trying to get somewhere – often at similar times such as rush hour. Keeping the motorways, highways and railways running, requires some sophisticated technology.

Traffic lights, speed cameras, electronic warning signs, and railway signals and point systems have to be synchronised for safety and efficiency. Any differences in time between traffic signals, for instance, could lead to traffic queues behind certain lights, and other roads remaining empty. While on the railways, if points systems are being controlled by an inaccurate clock, when the trains arrive the system may be unprepared or not have switched the line – leading to catastrophe.

Because of the need for secure, accurate and reliable time synchronisation on our transport systems, the technology that controls them is often synchronised to UTC using atomic clock time servers.

Most time servers that control such systems have to be secure so they make use of Network Time Protocol (NTP) and receive a secure time transmission either utilising atomic clocks on the GPS satellites (Global Positioning System) or by receiving a radio transmission from a physics laboratory such as NPL (National Physical Laboratory) or NIST (National Institute of Standards and Time).

In doing so, all traffic and rail management systems that operate on the same network are accurate to each other to within a few milliseconds of this atomic clock generated time and the NTP time servers that keep them synchronised ensures they stay that way, making minute adjustments to each system clock to cope with the drift.

NTP servers are also used by computer networks to ensure that all machines are synced together. By using a NTP time server on a network, it reduces the probability of errors and ensures the system is kept secure.

Origin of Synchronisation (Part 1)

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Part One

With modern NTP servers (Network Time Protocol) synchronisation is made easy. By receiving a signals from GPS or radio signals such as MSF or WWVB, computer networks consisting of hundreds of machines can easily be synchronised together, ensuring trouble free networking and accurate time-stamping.

Modern NTP time servers are reliant on atomic clocks, accurate to billions of parts of a second, but atomic clocks have only been around for the last sixty years and synchronisation has not always been so easy.

In the early days of chronology, clocks mechanical in nature, were not very accurate at all. The first time-pieces could drift by up to an hour a day so the time could differ from town clock to town clock, and most people in the agricultural based society regarded them as a novelty, relying in stead on sunrise and sunset to plan their days.

However, following the industrial revolution, commerce became more important to society and civilisation, and with it, the need to know what the time was; people needed to know when to go to work, when to leave and with the advent of railways, accurate time became even more crucial.

In the early days if industry, workers were often woken for work by people paid to wake them up. Known as ‛knocker-uppers.’ Relying on the factory time-peice, they would go around town and tap on people’s windows, alerting them to the start of the day, and the factory hooters signalled the beginning and end of shifts.

However, as commerce developed time became even more crucial, but as it would take another century or so for more accurate timepieces to develop (until at least the invention of electronic clocks), other methods were developed.

To follow…