Coordinated Universal Time or UTC is now the world’s time standard it took over from the old Greenwich Meantime (GMT) after the development of atomic clocks. UTC is based on GMT but accounts for the random variations of the Earth’s rotation by having leap seconds added once or twice a year.

By accounting for the Earth’s rotation, UTC can keep noon above the meridian line (as GMT) but can also be recorded by the highly accurate atomic clocks.

UTC is ‘Universal’ in that it allows the entire world to communicate with the same timescale. For us humans UTC accounts for the time-zones by having a positive or negative integer after the time. Here is the UTC time zones:

Fortunately computers aren’t bothered about timezones and when communicating together across global networks via a time server UTC is the same no matter where they are on in the world.

Computer time servers usually receive their UTC time from a source external to the internet such as the GPS signal which are directly broadcast via atomic clocks in doing so a time server can keep a computer network to within a few milliseconds of UTC.

A time server is a generic term for a device that receives and distributes time.  Time servers are available across the Internet or dedicated devices can be bought that offer higher accuracy and more security.

Whilst many manufacturers produce time server devices and other synchronisation tools they all have one thing in common in that they all utilise Network Time Protocol (NTP).

Whilst NTP is not the only time synchronisation software available it is used in the vast majority of synchronisation tools with some 99% of time synchronisation being conducted using NTP. NTP is a protocol used by everyone from NASA to NASDAQ and owes much of its dominance or the time synchronisation market to the dedicated team that continue to update, upgrade and develop NTP (many of whom do not get paid).

NTP is in fact almost as old as the Internet itself having been unveiled as early as 1979. It was developed by Professor David Mills and his team from Delaware University who continue to update and develop it alongside hundreds of dedicated hobbyists referred to as the Internet timekeepers.

NTP is now on version 4 and versions of NTP are included as standard with most operating systems allowing any Windows or Linux computer to run as a time server. However, for those serious about time synchronisation or wanting to keep a network secure there is no real substitute than a dedicated time server that can distribute time sent directly from an atomic clock using NTP.

A time server is an essential piece of equipment responsible for ensuring all devices on a computer network are running the same time. Most time servers are dedicated devices that receive a time signal, normally UTC (Coordinated Universal Time), and distribute it to all devices on a network.

Most time servers use the Internet protocol NTP (Network Time Protocol) to synchronise all devices and are often referred to as NTP servers. NTP distributes a single time source throughout the network which is normally a UTC source (Coordinated Universal Time).

There are several places a time server can receive a time signal from. The internet is an obvious source for many although online time sources are not very accurate, can be too far away to give any useful precision, and more importantly are not secure being as they are external to the firewall.

As a dedicated time server is an external device they are extremely secure and impossible for malicious users to tamper with. Dedicated time server can receive a time signal from two sources the GPS network (Global Positioning System) , a highly accurate method and available everywhere on the globe with a good view of the sky; or the specialist long wave radio transmissions broadcast by national physics laboratories.

In Europe the two main radio transmissions are the UK’s MSF signal broadcast by NPL (National Physical Laboratory) in Cumbria, England and the German DCF-77 broadcast near Frankfurt.

These long wave signals are also highly accurate and can be picked up in most neighbouring countries too. The USA has a similar system called WWVB,  transmitted by the National Institute for Standards and Technology (NIST) from Boulder, Colorado.

Time servers are incredibly important but an often overlooked part of a computer network. They are essential devices ensuring that all computers and devices connected to the network are synchronised to the same time. This prevents any problems from occurring when networks run sporadic time such as emails arriving before they were sent or even more serious security issues.

Time servers are similar to other servers but their sole role is to receive the time from a trusted source and distribute it amongst the network. The network time server can receive this time source from several places but in doing so one must have in mind two questions: How accurate is the time reference supplying the time? And how secure is it?

There are two highly accurate and completely secure methods of receiving the time for a time server. Both methods supply UTC (Coordinated Universal Time) which is a global timescale maintained by highly accurate atomic clocks. The first is to utilise the Global Positioning System (GPS) whose satellites all have onboard an atomic clock or the second is to use the national physics’ laboratories time and frequency transmissions.

Once a timing reference is received it is distributed to machines on a network using the protocol NTP (Network Time Protocol). NTP is based on an algorithm that not only corrects the time on any device but also ensures that the UTC time being received is secure, stable and precise.

NTP is one of the oldest Internet based protocols having been around since the 1980’s yet it is a testament to its developers that over twenty years on it is not only still in use but is by far the most common time protocol in use.

A time server is an integral part of any network system. It ensures all machines on a network or keeping the exact same time, failure to do so could lead to all sorts of problems, particularly with time sensitive transactions.

Most computer networks are synchronised to UTC (coordinated Universal Time). UTC is a global time scale and used throughout the world. It is also highly precise as it is based on the time told by atomic clocks.

Atomic clocks are ideal sources of time as they do not drift whilst the standard electrical oscillators on our PC clocks can drift by a second every week. This drift can cause untold problems which is why most networks are synchronised to a time server that receives a time signal from an atomic clock.

Atomic clock time signals can be received from a myriad of sources. The Internet is an obvious choice but unless security and precision is not an issue then it is not recommended for any commercial networks as using an Internet times source can leave a system open to security threats.

For security and accuracy there are two options to synchronise to an atomic clock. One is to use a GPS time server that receives the time-code from the GPS system. The other method is to use a time server that can receive the long wave radio transmissions broadcast from several national physics laboratories.

Physics laboratories across the globe transmit UTC (Coordinated Universal Time) radio broadcasts that can be received using a radio referenced time server. These time signals are an accurate and secure method of receiving UTC time.

Whilst many of these signals only have a limited range and are only available for certain periods several most notably the USA’s WWVB, Germany’s DCF and the UK’s MSF signals -provide a continuous and widespread broadcast that can be received 24 hours a day and even in neighbouring countries.

Here is alist of many of the World’s radio time server signals:

Table courtesy of the World Radio and TV Handbook.

NTS-8000-GPS

NTP Time Server with dual GPS and radio (MSF/DCF/WWVB) receiver

The Galleon NTS-8000-GPS Network Time Server combines a GPS based atomic radio clock with a radio receiver allowing dual signals to be received. The radio receiver can be tuned for either MSF(UK) WWVB (USA) or DCF (Germany). The NTS 8000 comes complete with Windows operating system based computer and offers straight forward configuration and management via the standard Windows interface using a keyboard and screen or remote access and connects directly to Ethernet, fitting in a standard 19″ rack.

NTS – 6000-GPS

NTP Time Server with integrated GPS receiver

The Galleon NTS-6000-GPS Network Time Server combines a GPS based radio clock with an embedded Linux solid state computer and offers straight forward configuration and management via a browser interface.

Connects directly to Ethernet and fits in a standard 19″ rack. The NTS 6000 incorporates a Galleon GPS Computer Clock which tracks up to 12 satellites. It comes complete with remote antenna that can be positioned up to 1,000m (3,000 ft) away with LCD signal strength display for easy installation.

NTS-4000- MSF/WWVB/DSF

NTP Time Server with integrated MSF/WWVB/DCF receiver

The Galleon NTS-4000- Network Time Server combines a radio receiver with an embedded solid state computer. It can be fitted with either a MSF/DCF o WWVB receiver module and offers straight forward configuration and management via a network interface.
Connects directly to Ethernet, fits in a standard 19” rack, 1U high and incorporates a Galleon Network time clock, with remote antenna that can be positioned up to 150m (450 ft) away as standard.  Conforms to Network Time Protocol Version 4 (NTP V4).

How accurate is the time you receive?

Unfortunately many Internet time servers are wholly inaccurate, however, this free and easy to use tool by Galleon Systems lets you check a server accuracy and reliability. Free to download and complete with instructions – an essential tool for anybody relying on the Internet for UTC time.

To download please visit Galleons NTP server site:

Galleon’s NTP server checker:

Here is a list of links to  some of the most reputable time server manufacturers and suppliers from all over the world by country of origin.

UK
France
Germany
Italy
Spain
Poland
North America
Middle East

What is a time server?

A time server is a hardware device that distributes a single time source amongst a network to ensure all computers and devices are synchronised

What is NTP?

Network Time Protocol is a set of software instructions designed to distribute time across computers. NTP uses a complex algorithm to work out d inaccuracies and compensates for them by advancing or retarding the system clock.

What is UTC?

Coordinated Universal Time (UTC) is the offical global timescale. It is used by computer networks throughout the world. It is based on the time told by atomic clocks but compensates for the slowing of the Earth’s rotation by adding Leap Seconds, this also keeps it inline with GMT (Greenwich Meantime) sometimes referred to as UT1.

How does a time server receive UTC?

UTC can be received by either tuning in to a national time and frequency broadcast on long-wave administered by national physics laboratories, although not every country has one. Alternatively as GPS satellites (Global Positioning System) all carry an onboard atomic clock which transmits timing information this can be used also as a timing source for network time servers.

Can’t I use the Internet as a timing source?

You can, and there are many sources of UTC time on the Internet but very few offer any useful accuracy and for those that do the distance away can cause a drop-off in precision. More importantly, Internet time sources are exterior to your firewall and therefore a port needs to be left open to ensure communication, this can be taken advantage of by malicious users. Also Internet timing sources can’t be authenticated; authentication is a security measure that ensures that a timing reference is what it says it is.

Which method is best for me a radio referenced time server or one that utilises the GPS network?

This depends on location. While GPS signals are available everywhere on the planet the antennas do have to have a clear view of the sky to receive the signal, alternatively radio transmissions are limited in their availability although where available the signals can be received indoors.

How accurate are time servers?

A radio referenced network time server can provide UTC time to an accuracy of 100 microseconds, while the GPS network can fare even better with accuracies of a few milliseconds reasonably possible.

One of the World’s leading suppliers of time servers are Galleon Systems based in the UK and Europe.

Their time servers provide:

* Automatic update of time with no user intervention required.

* Simple Installation

* Customised products: As the specialist supplier, with the widest product range of dedicated Time Servers in the World if we haven’t got the time synchronisation product you want contact us because we can modify the standard products to your specific requirements.

* Full product range, From Dedicated Rack Mount NTP Time Servers that synchronize the time of thousands of computers across a network to simple Atomic Clocks that connect to a single PC.

* Cost Effective by being a specialist in Time synchronisation, Galleon offers a full product range so you buy the correct product for you needs, not one designed for a Multinational corporation.

* Reliable, Galleon Atomic Clocks and NTP Time Servers are used by organizations world-wide and provide reliable time synchronization 24 hours a day 365 days a year.

* 3 Year warranty. Galleon offers a 3 year warranty on ServerARC, ServerGPS, WorkstationARC and WorkstationGPS NTP Time Server products

* Lifetime Technical support. At Galleon we believe that technical support should be free for as long as you want to use a Galleon product for.

* MSF and GPS: Uses the NPL MSF time signal or GPS satellites time. The MSF time signal provides the strongest radio time signal in the UK and can be received up to about a range of 937.5 miles. GPS satellites time can be received anywhere in the world. You can have both time sources linked to your Galleon NTP Time Server for redundancy in the event that one time source is not available.

Please given Galleon a call, before you LOSE TRACK OF TIME:

+44 (0)121 608 4433

Dedicated time servers are used throughout the world to ensure computer networks are synchronised. Not only does a synchronised network offer more security but synchronisation using a dedicated time server can offer legal protection.

Because dedicated time servers use such a secure and reliable method of keeping time (atomic clock signals from either the GPS network or radio broadcasts) the time can be legally audited to few milliseconds. However, networks synchronised using an Internet timing source can not be audited and this can leave these systems open to abuse or even fraud.

Dedicated time servers are also based behind a firewall ensuring the system is protected from any intrusion while an internet based timing source has to have access through the firewall through an open port.

Any company that requires security in its network or protection from fraud must ensure they are using either a  GPS or radio referenced time server.

A time server is a necessary part of any computer network. Time servers receive an authoritative time source that they then distribute amongst all devices on a network. Most time servers use a protocol such as NTP (Network Time Protocol) to distribute the single time source to all devices.

The accuracy of a time server depends entirely on the accuracy of the time source that it uses. Most networks require a UTC time source (coordinated universal time). UTC is a global timescale based on International atomic clock time (TAI) and used throughout the globe. Utilising UTC means that a computer network can be synchronised to the exact same time as a network on the other side of the globe allowing precise communications and time sensitive transactions to take place.

A time server can receive a UTC time source from only three places: the Internet, via a radio transmission or the GPS network.

The internet is by far the most commonly used source of UTC time. There are over a thousand time servers all claiming to relay UTC time. However, in surveys, less than half of these internet time sources are accurate and those that are, can be too far away to provide and real use as a timing source.

Using an internet timing source will also leave a computer network vulnerable. The hole left in the firewall to access the timing source can be used by malicious users and the built-in security method of NTP, authentication, can not ne utilised from across the Internet.

Fortunately, the two other methods of receiving UTC time offer both secure and reliable methods of receiving UTC time. The GPS network is available anywhere where there is a clear view of the sky whilst although not every country has a national time and frequency transmission, these longwave signals can be picked up by a radio referenced network time server from within a building.

Atomic clocks use an atomic resonance frequency standard as their timekeeping element and are by far the most accurate chronometers possible with the latest Strontium based atomic clocks boasting a precision of a less than a second lost in several hundred million years.

The clocks maintain a continuous and stable time scale called International Atomic Time (TAI). However, for civil time, another time scale, Coordinated Universal Time (UTC)which  is derived from TAI, but synchronized using leap seconds to UTC, to keep it based on the rotation of the Earth.

UTC is a global timescale that is commonly used to synchronise the clocks on computer networks allowing machines from across the globe to communicate together and conduct time sensitive applications.

Unfortunately atomic clocks are highly expensive pieces of equipment and are generally only to be found in high technology physics laboratories or onboard satellites. However, several national physics laboratories broadcast the time told by their atomic clocks via a long wave radio transmission.

These signals are commonly picked up and utilized by radio controlled wall and desk clocks and by NTP time servers (Network Time Protocol).

The transmissions from the national standards agencies maintain an accuracy of 10-9 seconds per day (approximately 1 part in 1014). MSF is the signal broadcast by National Physical Laboratory in, Anthorn, Cumbria. Other countries boast their own signals the most common being the DCF77 transmission broadcast from Mainflingen near Frankfurt, Germany and the USA’s WWVB signal broadcast from Fort Collins, Colorado.

All these times signals work in a similar way. At the start of each second the strength of the signal is either reduced by between 6 and 10 dB

A time server is a computer server that reads the time from an accurate clock and distributes this information to its clients across a computer network.

The reference used by a time server is normally a UTC (coordinated universal time) time source. UTC is a global time scale adopted all over the world and based on the time told by atomic clocks The most common source for UTC time is now the GPS system (global positioning system).

The most widely-used protocol for distributing and synchronising time is Network Time Protocol (NTP) which has been around almost as long as the Internet itself, having been developed in 1985 by Professor David Mills.

NTP receives the time from the time server and then checks or clocks on its networks to see if they need advancing or retreat.

To prevent overload of networks requesting timing information, NTP is hierarchical.  The term “stratum” is used to label the nearness to a stratum 0 server – that atomic clock. The higher the stratum number the further away the server is. A GPS time server is normally a stratum 1 device as it receives time from a stratum 0 device. However, stratum 2 and stratum 3 devices can still synchronise with each other.

Dedicated time servers are used despite the numerous Internet time sources available. The advantages of a dedicated time server is that the device is behind a firewall so preventing any security issues, dedicated time servers can also guarantee accuracy that is just not possible over the Internet.

The dedicated time server checks the time stamp from the UTC source (Coordinated Universal Time) and uses the information to calculate if the network clocks are drifting and adds or subtracts a second to match. The time server will do this at set intervals. Most time servers utilise NTP (network time protocol) although other protocols do exist NTP is by far the most widespread.

For NTP to distribute the time it first needs a timing source and this is where the differences in dedicated time servers come in. As UTC is based on the time told by atomic clocks, it is an atomic clocks that is the source for a time servers timing reference. Atomic clocks are extremely expensive, large, and require a multitude of maintenance engineers. For this reason they are only to be found in large scale physics laboratories.

However, the time from an atomic clock can still be utilised by using either a radio clock attached to a time server or a GPS clock. A radio clock is just a simple radio receiver that picks-up the long-wave signal broadcast by several national physics laboratories. This UTC signal is not available everywhere and the broadcast can be blocked by buildings, mountains and bad weather etc.

The other type of dedicated time server utilise the signals sent by the GPS satellites (global positioning system). These signals are available literally everywhere on the globe although the only downside is that a GPS antenna needs to have a clear view of the sky and therefore ideally needs to be situated on a roof which can cause some problems if the server room is along way from the top of the building.

Some dedicated time servers can actually receive both signals; the radio and GPS. In doing so they can continue receiving time signals even if one signal fails or gets temporarily blocked.

What is a time server?

A time server is a device that utilises a single time source and distributes it amongst a network. This enables all machines on a LAN (or WAN) to be synchronised together.

What is NTP?

Network Time Protocol is a protocol (a set of instructions) designed to distribute the time from a time server top a network.

Why do I need a time server?

It may well be that you don’t. Many small networks survive and operate perfectly without the need of a time server. However, if computers are required to do time sensitive transactions or applications then a time server is essential. Without proper synchronisation all sorts of unforeseen problems can arise and many of the online transactions that we take for granted such as seat reservation, Internet shopping, the stock exchange and even sending emails are reliant on perfect time synchronisation.

What is the best time reference to use?

A single global timescale based on the time told by atomic clocks has been developed called UTC (Coordinated Universal Time). UTC is utilised by networks all over the world. In using UTC you are in affect synchronising your network with every other network in the world that utilises UTC.

Where to I get UTC time from?

The most common and easiest location to receive UTC time is from across the Internet although Internet time sources are notoriously inaccurate. They also provide little security. Apart from the fact the time server is outside your firewall, NTP can’t authenticate these signals. Authentication is a security measure used by NTP to prevent malicious attacks that masquerade as a time server.
The most secure methods for receiving UTC time is by using either the GPS network (global positioning system), whose satellites transmit the timing information or alternatively by using specialist national time and frequency long-wave transmissions although these are not available everywhere.

Galleon Systems and their The NTS 4000 MSF S and the NTS 4000 GPS S are possibly the two least expensive time servers available anywhere.

They are simple to use NTP time servers receiving accurate time from the a radio time signal (MSF) or the GPS network and using NTP can provide this synchronised time via a Ethernet port to any computer, server, switch, etc that conforms to the Network Time Protocol V3. And unbelievably they can process 1,000 NTP requests per minute.

The identical looking units are attractive pieces of kit too:

Time servers are essential in keeping computer networks synchronised without them many time sensitive transactions would be impossible to conduct. Time servers work by receiving a signal timing reference and distribute it to all devices on a network using the protocol NTP (Network Time Protocol). The time signal used by most time servers comes from a UTC (Coordinated Universal Time) source. UTC is based on the time told by atomic clocks and is used globally, allowing computers from across the world to be synchronized to the same time reference.

There are three methods that time servers can receive the UTC signal from. Firstly, the internet, although unsecured and without any guarantees of accuracy Internet time references are only suitable for networks where precision and security are not a concern.

The second method is via the GPS network which is available everywhere but only where an antenna has a clear view of the sky.

The third and simplest method to receive an accurate and secure UTC time reference is to use the national time and frequency broadcasts. In the UK the National Physical Laboratory transmits the British signal from Anthorn in Cumbria. This signal, known as MSF, can be received in most places in the UK although local topography can interfere with the transmission.

To receive the MSF broadcast a radio referenced NTP time server is required. This will receive the radio transmission via 65 kHz in long wave and distribute it amongst the network.
A radio based NTP server usually consists of a rack-mountable time server, and an antenna, consisting of a ferrite bar inside a plastic enclosure, which receives the radio time and frequency broadcast. The antenna should always be mounted horizontally at a right angle toward the transmission for optimum signal strength.

Similar national timing transmissions are broadcast from other countries in the US the signal is referred to as WWVB and is broadcast by the NIST (National Institute for Standards and Technology) in Fort Collins, Colorado, other systems are broadcast in Frankfurt, Germany (DCF-77), Japan (JJY) and France ( TDF).

Computer networks rely on timekeeping for nearly all their applications, from sending an email to saving data, a timestamp is necessary for computer to keep track. All routers and switches need to run at the same rate, out of sync devices can lead to data being lost and even entire connections.

All PC’s and networking devices use clocks to maintain an internal system time. These clocks, called Real Time Clock chips (RTC) provide time and date information. The chips are battery backed so that even during power outages, they can maintain time.

However, personal computers are not designed to be perfect clocks, their design has been optimized for mass production and low-cost rather than maintaining accurate time. However, these internal clocks are prone to drift and although for many application this can be quite adequate, often machines need to work together on a network and if the computers drift at different rates the computers will become out of sync with each other and problems can arise particularly with time sensitive transactions.

For some transactions it is necessary for computers to be perfectly synchronised, even a few seconds difference between machines can have serious effects, such as finding an airline ticket you had booked had been sold moments later to another customer or you could draw your savings out of a cash machine and when your account is empty you could quickly going to another machine and withdraw it all again.

Time servers are like other computer servers in the sense they are usually located on a network. A time server gathers timing information, usually from an external hardware source and then synchronises the network to that time.

Most time servers use NTP (Network Time Protocol) which is one of the Internet’s oldest protocols still used, invented by Dr David Mills from the University of Delaware, it has been in utilized since 1985. NTP is a protocol designed to synchronize the clocks on computers and networks across the Internet or Local Area Networks (LANs).

NTP utilises an external timing reference and then synchronises all devices on the network to that time.

Often time servers are synchronised to a UTC (Coordinated Universal time) source which is the global standard time scale and allows computers all over the world to synchronised to exactly the same time. This has obvious importance in industries where exact timing is crucial such as the stock exchange or airline industry.

There are various sources that a time server can use as a timing reference. The Internet is an obvious source, however, internet timing references from the Internet such as nist.gov and windows.time can not be authenticated, leaving the time server and therefore the network vulnerable to security threats.

Just as your computer is only as good as the software it is running, a time server is only as useful as the timing source it uses. Time servers are similar to other servers in that they are located on a network but the primary function of a time server is to supply timing information rather than storing or routing data.

For computers a time stamp is the only point of a reference a computer can use to establish a sequence of events. Timestamps are used in everything from sending an email to debugging a system and ensuring your network is secure.

Nearly all time servers rely on NTP (Network Time Protocol) to synchronise devices once a timing source is selected Whilst it is not the only protocol designed for synchronisation it is by far the most widely used, primarily because it has been under constant development since its inception nearly three decades ago.

A NTP server works by receiving a time reference from an authoritative source, normally a UTC time source. UTC (Coordinated Universal Time) is an International timescale based on the time told by atomic clocks.

Unfortunately many administrators opt to use an Internet timing source to run their time server with. However, several studies of Internet timing references discovered that nearly two thirds were inaccurate by over several seconds (almost an eternity in the world of NTP) and those that weren’t were often too far away from a client to provide reliable accuracy.

Probably the most accurate and widely used method of retrieving a reliable time reference is to use a dedicated GPS Time Server, many national physics laboratories also broadcast the time told by their atomic clocks via long wave radio. These signals can be received by a time server if it is equipped with a radio receiver although not every country broadcasts one and the transmissions are susceptible to interference and local topography.

Once this secure UTC time reference is received the time server can then distribute the time across the network. The timestamp itself is represented as a single ascending number. The number is the amount of seconds from a prime epoch (start number) normally 01 January 1900. The time server checks the system clocks on its clients and advances or retracts the time until all machines on the network are synchronised.

Keeping track of time is something most people take for granted, yet the science of timekeeping has a long and fascinating history.

Keeping track of time was always based on the relationship between the Earth, Moon and Sun. The first timekeeping devices are thought to be monuments like Stone Henge in the UK that would recognise the winter or summer solstice allowing early man to calculate when to plant crops.

Dividing the day up into hours and being able to keep track of them has proved more difficult to civilisations.

The first timing devices were sundials, obelisks and water clocks but it wasn’t until the development of mechanical clocks in the middle-ages that time-telling started to become more accurate.

Mechanical clocks continued to develop until the turn of the twentieth century when they were bettered in accuracy by electronic oscillators that would use the resonance of a crystal (often quartz) to keep a stable time.

While electronic clocks provided accuracy to within a second a day, the atomic clock that uses the resonance of an atom (in most cases caesium -133) and was developed in the 1950’s demonstrated millisecond accuracy – not losing a second in several thousands of years.

Now atomic clocks are approaching nano-second accuracy (one second every billion years) with new developments like strontium. The atomic clock has also made horologists realise that basing a time system on the movement of the Earth and celestial bodies is unreliable as the Earth slows and speeds up.

UTC (coordinated universal time) was developed to combat this by adding leap seconds to keep atomic time in line with GMT (Greenwich Meantime). Now computer networks all over the world can synchronise to UTC and atomic clocks by using a time server.

A time server will receive a time from an atomic clock source and synchronise an entire network to this time. Without time servers, atomic clocks and UTC, technologies such as satellite communication, the Internet and global trading would be near impossible.

The atomic clock was developed in the 1950’s and represented a huge step forward in chronology. Before the atomic clock, electronic oscillators, as used in most digital clocks and watches, were providing the best accuracy although these would drift several seconds a month.

The atomic clock used the resonance of the atom caesium -133 which had an exact oscillation of 9,192,631,770 times a second. Because of this exact oscillation atomic clocks soon offered nearnano-second accuracy in that it would take several million years before they would drift by a second.

Atomic clocks were deemed so accurate that the International System of Units (SI) defined the second as this number of oscillations of the caesium atom.

As time-telling became so accurate it was soon discovered that the rotation of the Earth was not as precise as the clocks and that to keep atomic time relevant to Greenwich Meantime (GMT) and to stop night from slowly drifting into day a new timescale was developed calledUTC (Coordinated Universal Time) which accounted for the slowing of the Earth’s spin by adding ‘Leap Seconds’.

UTC is now globally used and allows the entire world to synchronise to the same timescale. This is particularly relevant for computer networks that often have to communicate with other networks across the globe.

UTC can be received by using a time server that can either synchronise to a timing reference across the Internet or for better accuracy an d security a time server can receiveUTC time from the GPS network via a GPS antenna or by receiving national timing broadcasts, transmitted form several countries.

By using a time server that receives UTC time a computer network can be accurate to within a few milliseconds of UTC allowing cross-global communication.

A time server is a computer device that obtains a timing reference from a  particular source and transfers it to a network and its clients.

A time server does not rely on a system clock for timing information (all though they can be set to) as the internal clocks in PCs are prone to drift. Instead a time server will request timing information from an authoritative source and synchronises to it.

Most time servers use NTP (network Time Protocol) to synchronise devices and networks using the information gathered by the time server.

Most network administrators prefer to get their timing reference from a hardware source, preferably one that relays UTC (Coordinated Universal Time) a global timescale based on the time told by atomic clocks.

Apart from Internet time sources, of which many  are inaccurate and can’t be authenticated there are two other methods to receive UTC time: the GPS network and national time and frequency transmissions.

A GPS time server will receive the timing information via an roof-mounted antenna whilst a radio receiving time server will utilise the national broadcasts of the US (WWVB), the UK (MSF), Germany (DCF), France (TDF) and Japan (JJY).

These broadcasts can’t be received everywhere and are vulnerable to local geography and interference.

GPS receivers are available everywhere on the planet so long as the antenna has a clear view of the sky.

Some dedicated time servers can receive both radio and GPS signals and can utilise both as a timing source, providing even more accuracy.

A time server receiving UTC time through either method can realistically provide accuracy to within a few milliseconds (1/1000th of a second) and can perform even better over LANs/WANs.

As important as telling the time is for the smooth running of our daily lives, it is even more essential for computer networks. Everything from sending and receiving email to debugging a network is dependent on a timestamp. If timestamps on machines differ then all sorts of complications can arise from email arriving before it was sent to systems being left vulnerable to attacks and even fraud.

Computer networks use Network Time Protocol (NTP) to synchronise their networks to an authoritative time source. The ideal sources are those that relay UTC (Coordinated Universal Time). UTC was developed after the invention of atomic clocks and is a global timescale that allows computer networks and devices all over the world to synchronise to the exact same time.

There are different ways to receive UTC most commonly is from an Internet source. However, Internet timing sources vary in accuracy and are affected by distance and bandwidth problems. Also, Microsoft and others suggest they should not be used as they can’t be authenticated. This is a security measure used by NTP to ensure that a servers is what it is supposed to be.

Fortunately a dedicated time server can receive a UTC source from either a specialist radio broadcast (available in certain countries only – including France, Germany, UK, USA and Japan) or the GPS network (available anywhere on Earth).

Not only can a dedicated time server provide accuracy to within a few milliseconds of UTC it can also be authenticated by NTP ensuring security.

Dedicated time servers are relatively inexpensive and simple to install and can allow networks of hundreds and even thousands to be synchronised to UTC.