Category: Time Synchronisation

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.

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.

Origin of Synchronisation (Part 2)

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Continued…

Most towns and cities would have a main clock, such as Big Ben in London, and for those living near-by, it was fairly easy to look out the window and adjust the office or factory clock to ensure synchronicity; however, for those not in view of these tower clocks, other systems were used.

Commonly, somebody with a pocket watch would set the time by the tower clock in the morning and then go around businesses and for a small fee, let people know exactly what the time was, thus enabling them to adjust the office or factory clock to suit.

When, however, the railways began, and timetables became important it was clear a more accurate method of time keeping was needed, and it was then that the first official time-scale was developed.

As clocks were still mechanical, and therefore inaccurate and prone to drift, society again turned to that more accurate chronometer, the sun.

It was decided that when the sun was directly above a certain location, that would signal noon on this new time-scale. The location: Greenwich, in London, and the time-scale, originally called railway time, eventually became Greenwich Meantime (GMT), a time-scale that was used until the 1970’s.

Now of course, with atomic clocks, time is based on an international time-scale UTC (Coordinated Universal Time) although its origins are still based on GMT and often UTC is still referred to as GMT.

Now with the advent of international trade and global computer networks, UTC is used as the basis of nearly all international time. Computer networks deploy NTP servers to ensure that the time on their networks are accurate, often to a thousandth of a second to UTC, which means all around the world computers are ticking with the same accurate time – whether it is in London, Paris, or New York, UTC is used to ensure that computers everywhere can accurately communicate with each other, preventing the errors that poor time synchronisation can cause.

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…

The Accuracy of the Speaking Clock

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The UK speaking clock has been around for nearly eighty years. It was started in 1936 when time keeping started to become more important to people’s lives. Initially available only in the London it was rolled out to the whole country during World War II.

There have been four people that have had honour of providing the permanent voice to the speaking clock over the last 70. And over 70 million calls are made to the speaking clock making it an important from of accurate time but have you ever wondered how accurate it is and where the time comes from and how accurate it is?

The speaking clock is controlled by a major British telecoms company who took over the General Post Office (GPO) and the time was originally supplied by the National Physical Laboratory (NPL) who also provide the MSF signal that NTP time servers use as a source of atomic clock synchronisation.

NPL no longer help with the speaking clock but the time is still controlled by NTP servers, either GPS or MSF, which ensures that the time you hear on the end of the telephone is accurate.

NTP servers are also commonly used by computer networks to ensure that IT systems, from traffic light signals to the office PC are all running an accurate form of time.

NTP time servers can either receive the MSF radio signal broadcast by NPL or, more commonly now, GPS signals beamed directly from space.

Often network administrators opt to use online NTP servers that send time signals over the internet but these are not as accurate and cause security problems so it is far better to have a dedicated NTP time server to control the time if you wish to have a computer network that is running accurately.

Do I Really Need an NTP Time Server?

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NTP (Network Time Protocol) is one of the oldest protocols still in use today. It was developed in the 1980’s when the internet was still in its infancy and was designed to help computers synchronise together, preventing drift and ensuring devices can communicate with unreliable time causing errors.

NTP is now packaged in most operating systems and forms the basis for time synchronisation in computers, networks and other technologies. Most technologies and networks use a network time server (commonly called an NTP time server) for this task.

These time servers are external devices that receive the time from a radio frequency or GPS signal (both generated by atomic clocks). This time signal is then distributed across the network using NTP ensuring all devices are using the exact same time.

As NTP is ubiquitous in most operating systems and the internet is awash with sources of atomic clock time, this begs the question of whether NTP time servers are still necessary for modern computer networks and technology.

There are two reasons why networks should always use a NTP time server and not rely on the internet as a source of time for synchronisation. Firstly, internet time can never be guaranteed. Even if the source of time is 100% accurate and kept true (incidentally most sources of internet time are derived using an NTP time server at the host’s end) the distance from the host can lead to discrepancies.

Secondly, and perhaps fundamentally more important to most business networks is security. NTP time servers work externally to the network. The source of time either radio of GPS, is secure, accurate and reliable and as it is external to the network it can’t be tampered with en-route, or used to disguise malicious software and bots.

NTP servers don’t require an open port in the firewall, unlike internet sources of time which can be used as an entry point by malicious users and software.

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.

Using Atomic Clock Time Signals

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Accuracy is becoming more and more relevant as technology becomes increasingly important to the functioning of our everyday lives. And as our economies become more reliant on the global marketplace, accuracy and synchronisation of time is very important.

Computers seem to control much our daily lives and time is essential for the modern computer network infrastructure. Timestamps ensure actions are carried out by computers and are the only point of reference IT systems have for error checking, debugging and logging. A problem with the time on a computer network and it could lead to data getting lost, transactions failing and security issues.

Synchronisation on a network and synchronisation with another network that you communicate with are essential to prevent the above mentioned errors. But when it comes to communicating with networks across the globe things can be even trickier as the time on the other-side of the world is obviously different as you pass each time-zone.

To counter this, a global timescale based on atomic clock time was devised. UTC – Coordinated Universal Time – does away with time-zones enabling all networks across the globe to use the same time source – ensuring that computers, no matter where they are in the world, are synchronised together.

To synchronise a computer network, UTC is distributed using the time synchronisation software NTP (Network Time Protocol). The only complication is receiving a source of UTC time as it is generated by atomic clocks which are multi-million dollar systems that are not available for mass use.

Fortunately, signals from atomic clocks can be received using a NTP time server. These devices can receive radio transmissions that are broadcast from physic laboratories which can be used as a source of time to synchronise an entire network of computers to.

Other NTP time servers use the signals beamed from GPS satellites as a source of time. The positioning information in these signals is actually a time signal generated by atomic clocks onboard the satellites (which is then triangulated by the GPS receivers).

Whether it’s a radio referenced NTP server or a GPS time server – an entire network of hundreds, and even thousands of machines can be synchronised together.

The Effects of No Time Signal

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NTP servers (Network Time Protocol) are an essential tool in the modern computer network. They control the time, ensuring every device on the network is synchronised.

Because of the importance of time in controlling nearly every aspect of computer networking accurate and synchronised time is essential which is why so many system administrators deploy a NTP time server.

These time servers use a single time source as a base to set all the clocks on a network to; the time is often got from the GPS network or radio signals broadcast from physics laboratories such as NPL in the UK (whose signal is broadcast from Cumbria).

Once this signal is received by the time server, the time protocol NTP then distributes it around the network – comparing the system clock of every device to the time reference and adjusting each device. By regularly assessing the drift of these devices and correcting for them NTP keeps clocks accurate to within milliseconds of the time signal and when this signal emanates from an atomic clock – it ensures the network is as accurate as physically possible, but what happens if you lose the time signal?

Damaged GPS antennas, maintenance of time signal transmitters or technical faults can lead to a NTP time sever failing to receive a time signal. Often, this is only temporary and normal service is resumed within a few hours but what happens if it doesn’t, and what is the effect of having a failed time signal?

Fortunately, NTP has back-up systems for just such an eventuality. If a time signal fails and there is no other source of time, NTP cleverly uses the average time from all the clocks on its network. So if some clocks have drifted a few milliseconds faster, and others a few milliseconds slower – then NTP takes the average of this drift ensuring that the time remains accurate for as long as possible.

Even if a signal has failed for several days – or even weeks – without knowledge of the system users, this does not mean the network will drift apart. NTP will still keep the entire network synchronised together, using the average drift, and while the longer the time signal remains off the les accurate the network will be it can still provide millisecond accuracy even after a few days of no time reference.