The Way an Atomic Clock Works

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Atomic clocks are the most accurate chronometers we have. They are millions of times more accurate than digital clocks and can keep time for hundreds of millions of years without losing as much as a second. Their use has revolutionised the way we live and work and they have enabled technologies such as satellite navigation systems and global online commerce.

But how do they work? Strangely enough, atomic clocks work in the same way as ordinary mechanical clocks. But rather than have a coiled spring and mass or pendulum they use the oscillations of atoms. Atomic clocks are not radioactive as they do not rely on atomic decay instead they rely on the tiny vibrations at certain energy levels (oscillations) between the nucleus of an atom and the surrounding electrons.

When the atom receives microwave energy at exactly the right frequency, it changes energy state, this state is constant an unchanging and the oscillations can be measured just like the ticks of a mechanical clock. However, while mechanical clocks tick every second, atomic clocks ‘tick’ several billion times a second. In the case of caesium atoms, most commonly used in atomic clocks, they tick 9,192,631,770 per second – which is now the official definition of a second.

Atomic clocks now govern the entire global community as a universal timescale UTC (Coordinated Universal Time) based on atomic clock time has been developed to ensure synchronization. UTC atomic clock signals can be received by network time servers, often referred to as NTP Servers, that can synchronize computer networks to within a few milliseconds of UTC.

Benefits of Accurate Network Time Synchronization

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Your computer probably does hundreds and thousands of tasks a day. If that is part of a network then the number of tasks could be millions. From sending emails to saving data, and everything else your computer is tasked to do, they are all logged by the computer or server.

Computers use timestamps to logo processes and indeed, timestamps are used as the only method a computer has to indicate when and if a task or application has been conducted. Timestamps are normally a 16 or 32 bit integer (one long number) that counts back the seconds from a prime epoch – normally 01 January 1970.

So for every task you computer does it will be stamped with the number of seconds from 1970 that the transaction was conducted. These timestamps are the only piece of information a computer system has to ascertain what tasks have been completed and what tasks have yet to be instigated.

The problem with computer networks of more than one machine is that the clocks on individual devices are not accurate enough for many modern time sensitive applications. Computer clocks are prone to drift they are typically based on inexpensive crystal oscillator circuits and can often drift by over a second a day.

This may not seem much but in today’s time sensitive world a second can be a long time indeed especially when you take into account the needs of industries like the stock exchange where a second can be the difference in price of several percent or online seat reservation, where a second can make the difference between an available seat and one that is sold.

This drift is also accumulative so within only a few months the computer systems could be over a minute out of sync and this can have dramatic effects on time sensitive transactions and can result in all sorts of unexpected problems from emails not arriving as a computer thinks they have arrived before they have been sent to data not being backed up or lost completely.

A NTP time server or network time server are increasingly becoming crucial pieces of equipment for the modern computer network. They receive an accurate source of time from an atomic clock and distribute it to all devices on the network. As atomic clocks are incredibly accurate (they won’t drift by a second even in a 100,000 years) and the protocol NTP (Network Time Protocol) continually checks the devices time against the master atomic clock time – it means the computer network will be able to run perfectly synchronised with each device within a few milliseconds of the atomic clock.

Life Without the Atomic Clock

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When we consider the most important inventions of the last 100 years, very few people will think of an atomic clock. In fact, if you ask somebody to come up with a top ten of inventions and innovations its doubtful if the atomic clock would figure at all.

Its probably not hard to imagine what people think of as the most life-changing inventions: the Internet, mobile phones, satellite navigation systems, media players etc.

However, nearly all theses technologies rely on accurate and precise time and they would not function without it. The atomic clocks lies at the heart of many of the modern innovations, technologies and applications associated with them.

Let’s take the Internet as an example. The Internet is, in its simplest form, a global network of computers, and this network spans time zones and countries. Now consider some of the things we use the Internet for: online auctions, Internet banking or seat reservation for example. These transactions could not be possible with precise and accurate time and synchronisation.

Imagine booking a seat on an airline at 10am and then another customer tries to book the same seat after you on a computer with a slower clock. The computer only has the time to go on so will consider the person who booked after you to have been the first customer because the clock says so! This is the reason any Internet network that requires time sensitive transactions is connected to a NTP server to receive and distribute an atomic clock time signal.

And for other technologies the atomic clock is even more crucial. Satellite navigation (GPS) is a prime example. GPS (Global Positioning System) works by triangulating atomic clock signals from satellites. Because of the high velocity of radio waves an inaccuracy of 1 second could see a sat-nav device out by 100,000 km.

Other technologies too from mobile phone networks to air traffic control systems are completely reliable on atomic clocks demonstrating how underrated this technology is.

Closed Circuit Cameras are Useless Without a Network Time Server

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For those of us that live in Britain, the CCTV camera (closed circuit TV) will be a familiar site on the high streets. Over four million cameras are in operation throughout the British Isles with every major city being monitored by state funded cameras which has cost the British taxpayer over £200 million ($400 million).

The reasons for use of such widespread surveillance have always been declared as to prevent and detect crime. However, critics argue that there is little evidence that CCTV cameras have done anything to dent the rising street crime on the UK’s streets and that the money could be better well spent.

One of the problems of CCTV is that many cities have both cameras controlled by local councils and privately controlled cameras. When it comes to crime detection the police often have to obtain as much evidence as possible which often means combining the different local authority controlled CCTV cameras with the privately controlled systems.

Many local authorities synchronise their CCTV cameras together, however, if the police have to obtain images from a neighbouring borough or from a private camera these may not be synchronised at all, of if so, synchronised to a different time completely.

This is where CCTV falls down in the fight against crime. Just imagine a suspected criminal is spotted on one CCTV camera committing a criminal act. The time on the camera could say 11.05pm but what if the police follow the suspects movements across a city and use footage from a privately owned camera or from other boroughs and while the CCTV camera that caught the suspect in the act may say 11.05, the other camera could spot the suspect minutes later only for the time to be even earlier. You could imagine a good defence lawyer taking full advantage of this.

To ensure their worth in the fight against crime, it is imperative that CCTV cameras are time synchronized using a network time server. These times servers ensure every device (in this case camera) is running the exact same time. But how do we ensure all cameras are synchronised to the same time source. Well fortunately, a global time source known as UTC (coordinated Universal Time) has been developed for this exact purpose. UTC is what governs computer networks, air traffic control and other time sensitive technologies.

A CCTV camera using a NTP server that receives a UTC time source from an atomic clock will not only be accurate but the time told on the devices will be provable in court and accurate to a thousandth of a second (millisecond).

Configuring a Network to use a NTP Server Part one: Finding a Time Source

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Keeping your network synchronized with the correct time is crucial for modern networking. Because of the value of timestamps in communciating globally and across multi-networks, it is imperative that every machine is running a source of UTC (Coordinated Universal Time).

UTC was developed to allow the entire global community to use the same time no matter where they are on the globe as UTC doesn’t use time-zones so it allows accurate communication regardless of location.

However, finding a source of UTC is often where some network administrators fall down when they are attempting to synchronize a network. There are many areas that a source of UTC can be received from but very few that will provide both accurate and secure reference to the time.

The internet is full of purported sources of UTC, however, many of them offer no where near their acclaimed accuracy. Furthermore, resorting to the internet can lead to security vulnerabilities.

Internet time sources are external to the firewall and therefore a hole has to be left open which can be taken advantage of by malicious users. Furthermore, NTP, the protocol used to distribute and receive time sources, cannot instigate its authentication security measure across the internet so it is not possible to ensure the time is coming from where it is supposed to.

External sources of UTC time are far more secure. There are two methods used by most administrators. Long wave radio signals as broadcast by national physics laboratories and the GPS signal which is available everywhere on the globe.

The external sources of UTC ensure your NTP network is receiving not just an accurate source of UTC but also a secure one.

Computer Network Timing Solutions

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Computer networks and the internet have dramatically changed the way we live our lives. Computers are now in constant communication with each other making possible transactions such as online shopping, seat reservation and even email.

However, all this is only possible thanks to accurate network timing and in particular the use of Network Time Protocol (NTP) used to ensure all machines on a network are running the same time.

Timing synchronization is crucial for computer networks. Computers use time in the form of timestamps as the only marker to separate two events, without synchronization computers have difficulty in establishing the order of events or indeed if an event has happened or not.

Failing to synchronize a network can have untold effects. Emails may arrive before they are sent (according to the computer’s clock), data may get lost or fail to store and worst-of-all, the entire network could be vulnerable to malicious users and even fraudsters.

Synchronization with NTP is relatively straight forward as most operating systems have a version of the time protocol already installed; however, choosing a timing reference to synchronize to is more challenging.

UTC (Coordinated Universal Time) is a global timescale governed by atomic clocks and is used by nearly all computer networks across the globe. By synchronizing to UTC a computer network is essentially synchronizing the network time with ever other computer network in the world that uses UTC.

The internet has plenty of sources of UTC available but security issues with the firewall means the only safe method of receiving UTC is externally. Dedicated NTP time servers can do this using either long wave radio or GPS satellite transmissions.

Using a NTP Server in your Network

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The Network Time Protocol server is used in computer networks all over the world. It keeps an entire network’s systems and devices synchronised to the same time, normally a source of UTC (Coordinated Universal Time).

But is a NTP time server a necessary requirement and can your computer network survive without one?  The short answer is perhaps yes, a computer network can survive without a NTP server but the consequences can be dramatic.

Computers are meant to make our lives easier but any network administrator will tell you they can cause an awful amount of difficulty when they inevitably go wrong and without adequate time synchronisation, identifying an error and putting it right can be nearly impossible.

Computers use the time in the form of a timestamp as the only reference they have to distinguish between two events. Whilst computers and networks will still function without adequate synchronisation they are extremely vulnerable. Not only is locating and correcting errors extremely difficult if machines are not synchronised the network will be vulnerable to malicious users and viral software that can take advantage of it.

Furthermore, failing to synchronise to UTC can cause problems if the network is to communicate with other networks that are synchronised. Any time sensitive transactions could fail and the system could be open to potential fraud or other legal implications as proving the time of a transaction could be near impossible.

NTP servers are easy to install and receive the UTC time signal from either long wave transmissions or the GPS satellite network which they then distribute amongst the network’s machines. As a dedicated NTP time server operates externally to the network firewall it does so without compromising security.

Does my Computer Network Need to be Synchronized to an Atomic Clock?

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Time synchronization with network time protocol servers (NTP servers) is now a common consideration for network administrators, although, keeping exact time as told by an atomic clock on a computer network is often seen as unnecessary by some administrators

So what are the advantages of synchronizing to an atomic clock and is it necessary for your computer network?  Well the advantages of having accurate time synchronization are manifold but it is the disadvantages of not having it that are most important.

UTC time (Coordinated Universal Time) is a global timescale that is kept accurate by a constellation of atomic clocks from all over the world. It is UTC time that NTP time servers normally synchronize too. Not just that it provides a very accurate time reference to for computer networks to synchronize too but also it is used by millions of such networks across the globe therefore synchronizing to UTC is equivalent to synchronizing a computer network to every other network on the globe.

For security reasons it is imperative that all computer networks are synchronized to a stable time source. This doesn’t have to be UTC any single time source will do unless the network conducts time sensitive transactions with other networks then UTC becomes crucial otherwise errors may occur and these can vary from emails arriving before they were despatched to loss of data.  However, as UTC is governed by atomic clocks it makes it a highly accurate and auditable source of time.

Some network administrators take the shortcut of using an internet time server as a source of UTC time, forgoing the need for a dedicated NTP device. However, there are security risks in doing such a thing. Firstly, the inbuilt security mechanism used by NTP, called authentication, which confirms a time source is where and who it claims it is, is unavailable across the internet. Secondly, internet time servers are outside the firewall which means a UDP port needs to be left open to allow the time signal traffic. This can be manipulated by malicious users or viral programs.

A dedicated NTP time server is external to the network and receives the UTC atomic clock time from with either the GPS satellite system (global positioning system) or specialist radio transmissions broadcast by national physics laboratories.

Facts of Time

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From wristwatches to atomic clocks and NTP time servers, the understanding of time has become crucial for many modern technologies such as satellite navigation and global communications.

From time dilation to the effects of gravity on time, time has many weird and wonderful facets that scientists are only beginning to understand and utilise. Here are some interesting, weird and unusual facts about time:

•    Time is not separate from space, time makes up what Einstein called four dimensional space time. Space time can be warped by gravity meaning that time slows down the greater the gravitational influence.  Thanks to atomic clocks, time on earth can be measured at each subsequent inch above the earth’s surface. That means that every bodies feet are younger than their head as time runs slower the lower to the ground you get.

•    Time is also affected by speed. The only constant in the universe is the speed of light (in a vacuum) which is always the same. Because of Einstein’s famous theories of relativity anybody travelling at close to the speed of light a journey to an observer that would have taken thousands of years would have passed within seconds. This is called time dilation.

•    There is nothing in contemporary physics that prohibits time travel both forward and backwards in time.

•    There are 86400 seconds in a day, 600,000 in a week, more than 2.6 million in a month and more than 31 million in a year. If you live to be 70 years old then you will have lived through over 5.5 billion seconds.

•    A nanosecond is a billionth of a second or roughly the time it takes for light to travel about 1 foot (30 cm).

•    A day is never 24 hours long. The earth’s rotation is speeding up gradually which means the global timescale UTC (coordinated universal time) has to have leap seconds added once or twice a year. These leap seconds are automatically accounted for in any clock synchronization that uses NTP (Network Time Protocol) such as a dedicated NTP time server.

Synchronizing the Time on your Computer

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Keeping accurate time is essential for many applications and dedicated NTP time servers make the job easy for network administrators. These devices receive an external time signal, often from GPS or sometimes from broadcast signals put out by organisations such as NIST, NPL and PTB (national physics labs from US, UK and Germany).

Synchronization with a NTP time server is made all the more easier thanks to NTP (network time protocol) this software protocol distributes the time source by constantly checking the time on all devices and adjusting any drift to match the time signal that is received.

Time synchronization is not just the concern of large networks. Even single machines and routers ought to be synchronised because at the very least it will help keep a system secure and make error detection a whole lot easier.

Fortunately, most versions of Windows contain a form of NTP. Often it is a simplified version but it is enough to allow a PC to be synchronized with the global time scale UTC (Coordinated Universal Time). On most Windows machines this is relatively easy to do and can be achieved by double clicking on the clock icon in the task bar then selecting a time provider in the internet time tab.

These time sources are internet based meaning that they are external to the firewall so a UDP port has to be left open to allow the time signal to enter. This can cause some security issues so for those wanting perfect synchronization without any security issues then the best solution is to invest in a dedicated time server. These need not be expensive and as they receive an atomic clock time signal externally then here is no breach in the firewall leaving your network secure.