Posts by: Richard N Williams

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.

Finding an Online NTP Time Source

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Finding a source of time to synchronise a computer network to can be a challenge as there are a myriad of online time sources, all pertaining to be accurate and reliable; however, the truth can be rather different with many online sources either in too much demand, too far away or inaccurate.

NTP (Network Time Protocol) requires a source of UTC time (Coordinated Universal Time) which is kept true by atomic clocks. Online time sources are not themselves atomic clocks but NTP server devices that receive the time from an atomic clock which is then relayed to the devices that connect to the online time server.

There are two types of online time server: stratum 1 devices – devices that receive the time directly from an atomic clock, either using GPS or a radio reference signal. Stratum 2 devices  on the other hand are one step further away in that they are receive their time from a stratum 1 time server.

Because of demand, finding an online stratum 1 time server is next to impossible, and those that do take request usually do so under a subscription, which leaves the only choice for most people being a stratum 2 device.

There are plenty of resources on the internet that provide locations for online time servers.

But there are drawbacks to using such devices; firstly, online stratum 2 time sources can’t be guaranteed and several surveys taken have found that the reliability and accuracy of many of them can’t be taken for granted.  Secondly, online sources of time require an open firewall port which can be manipulated by malicious bots or users – leading to security risks.

A far better solution for most networks is to install your own stratum 1 NTP server. These time server devices sync to atomic clocks outside the firewall (using GPS or radio signals) and therefore are not security risks. They are also accurate to a few milliseconds ensuring the network will always be accurate to UTC.

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.

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.

Using Atomic Clocks for Time Synchronisation

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The atomic clock is unrivalled in its chronological accuracy. No other method of maintaining time comes close to the precision of an atomic clock. These ultra-precise devices can keep time for thousands of years without losing a second in drift – in comparison to electronic clocks, perhaps the next most accurate devices, which can drift up to a second a day.

Atomic clocks are not practical devices to have around though. They use advanced technologies such as super-coolant liquids, lasers and vacuums – they also require a team of skilled technicians to keep the clocks running.

Atomic clocks are deployed in some technologies. The Global Positioning System (GPS) relies on atomic clocks that operate onboard the unmanned orbiting satellites. These are crucial for working out accurate distances. Because of the speed of light that the signals travel, a one second inaccuracy in any GPS atomic clock would lead to positing information being out by thousands of kilometres – but the actual accuracy of GPS is within a few metres.

While these wholly accurate and precise instruments for measuring time are unparalleled and the expensive of running such devices is unobtainable to most people, synchronising your technology to an atomic clock, in actual fact, is relatively simple.

The atomic clocks onboard the GPS satellites are easily utilised to synchronise many technologies to. The signals that are used to provide positioning information can also be used as a source of atomic clock time.

The simplest way to receive these signals is to use a GPS NTP server (Network Time Protocol). These NTP servers use the atomic clock time signal from the GPS satellites as a reference time, the protocol NTP is then used to distribute this time around a network, checking each device with the GPS time and adjusting to ensure accuracy.

Entire computer networks can be synchronised to the GPS atomic clock time by using just one NTP GPS server, ensuring that all devices are within milliseconds of the same time.

NTP and GPS-based Timing Solutions

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Ask anybody what the key to network timing is and you will probably get the response NTP (Network Time Protocol).  NTP is a protocol that distributes and checks the time on all network devices to a reference clock – and it is this reference which is the true key to network time synchronisation.

Whilst a version of NTP is easy to obtain – it is normally installed on most operating systems, or is otherwise free to download – but getting a source of time is where the true key to network time synchronisation lies.

Atomic clocks govern the global timescale UTC (Coordinated Universal Time) and it is this timescale that is best for network timing as synchronising all devices on a network to UTC is equivalent of having you network synchronised with every other UTC synced network on Earth.

So getting a source of UTC time is the true key to accurate network time synchronisation, so what are the options?

Internet Time Sources

The obvious choice for most NTP users, but internet time suffers from two major flaws; firstly, internet time operates through the firewall and is therefore fraught with security risks – if the time can get through your firewall, then other things can too. Secondly, internet time sources can be hit and miss with their accuracy.

Due to the fact most internet time sources are stratum 2 devices (they connect to another device that receives the UTC source time) and the distance from client to host can never be truly ascertained or accounted for – it can make them inaccurate – with some internet time sources minutes, hours and even days away from true UTC time.

Radio Referenced Time Server

Another source of UTC time which doesn’t suffer from either security or accuracy flaws is receiving the time from long wave radio signals that some country’s national physics laboratories broadcast. While these signals are available throughout the USA (courtesy of NIST) the UK (NPL) and several other European countries and can be picked up witha basic radio referenced NTP server they are not available everywhere and the signals can be difficult to receive in some urban locations or anywhere where there is electrical interference.

GPS-timing

For completely accurate, secure and a reliable source of UTC time there is no substitute for GPS time. GPS timing signals are beamed directly from atomic clocks onboard the GPS satellites (Global Positioning System) and received by GPS NTP time servers. These can then distribute the atomic clock time around the network.

GPS timing sources are accurate, secure and available literally anywhere on the planet 24 hours a day.

Time Synchronisation of Technology

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Many technologies are reliant and precise, accurate and reliable time. Time synchronisation is vital in many technical systems that we encounter everyday, from CCTV cameras and ATMs to air traffic control and telecommunication systems.

Without synchronisation and accuracy many of these technologies would become unreliable and in could cause major problems, even catastrophic ones in the case of air traffic controllers.

Precise time and synchronisation also plays an increasingly important part in modern computer networking, ensuring the network is secure, data is not lost, and the network can be debugged. Failing to ensure a network is synchronised properly can lead to many unexpected problems and security issues.

Ensuring accuracy

To ensure accuracy and precise time synchronisation modern technologies and computer networks the time controlling Network Time Protocol (NTP) is most commonly employed. NTP ensures all devices on a network, whether they are computers, routers, CCTV cameras or almost any other technology, are maintained at the exact same time as every other device on the network.

It works by using a single time source that it then distributes around the network, checking for drift, and correcting devices to ensure parity with the time source. It has many other features such as being able to assess errors and calculating the best time from multiple sources.

Obtaining the time

When using NTP, getting the most accurate source of time allows you to keep your network synchronised – not just together but also synchronised to every other device or network that uses that same time source.

A global timescale known as Coordinated Universal Time (UTC) is what most NTP servers and technologies use. A sit is a global timescale, and is not concerned with time zones and daylight saving, UTC allows networks across the world to communicate precisely with the exact same time source.

NTP time servers

Despite their being many sources of UTC across the internet, these are not recommended for accuracy and security reasons; to receive an accurate source of NTP there are really only two options: using a NTP time server that can receive radio transmissions from atomic clock laboratories or by using the time signals from GPS satellites.

Windows Server and the Importance of NTP

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Windows Server is the most common operating system used by business networks. Whether it is the latest Windows Server 2008 or a previous incarnation such as 2003, most computer networks used in trade and business have a version.

These network operating systems make use of the time synchronization protocol NTP (Network Time Protocol) to ensure synchronicity between all devices connected to the network. This is vital in the modern world of global communication and trade as a lack of synchronization can cause untold problems; data can get lost, errors can go undetected, debugging becomes near impossible and time sensitive transactions can fail if there is no synchronization.

NTP works by selecting a single time source and it be checking the time on all devices on the network, and adjusting them, it ensures the time is synchronised throughout. NTP is capable of keeping all PCs, routers and other devices on a network to within a few milliseconds of each other.

The only requirement for network administrators is to select a time source – and this is where many IT professionals commonly go wrong.

Internet time servers

Any source of time to synchronize a network to should be UTC (Coordinated Universal Time) which is a global timescale controlled by the world’s most accurate atomic clocks and the number one source for finding a UTC time server is the internet.

And many network administrators opt to use these online time servers thinking they are an accurate and secure source of time; however, this is not strictly the case. Internet time servers send the time signal through the network firewall which means viruses and malicious users can take advantage of this ‘hole.’

Another problem with internet time servers is that their accuracy can’t be guaranteed. Often they are not as accurate as a profession network requires and factors such as distance away from the host can make differences in the time.

Dedicated NTP time server

Dedicated NTP time servers, however, get the time directly from atomic clocks – either from the GPS network or via secure radio transmissions from national physics laboratories. These signals are millisecond accurate and 100% secure.

For anyone running a network using Windows Server 2008 or other Microsoft operating system should seriously consider using a dedicated NTP server rather than the internet to ensure accuracy, reliability and security.

An End to British Summer Time?

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The new UK government is to look again at the perennial debate about changing the clocks during the summer months from GMT (Greenwich Mean Time) to British Summer Time (BST).

While the move is controversial, with many in Scotland in the north of the UK, unwilling to adopt the change due to the longer dark days of winter they experience over the rest of the country – the move would help synchronise Britain with the rest of Europe.

Despite its positing in the European Union, Britain holds a different timescale to the rest of Europe. People from the UK who travel abroad have to advance their watches an hour every-time they travel to mainland Europe.

In the new proposals, daylight saving time will still continue but the standard winter time will be advanced an hour and a further advancement of an hour for the summer – know as double British Summertime – allowing the UK to have the same time as Europe.

However, despite the problems such a change would have to people; technology will not be affected by any alteration in daylight saving time.

UTC Time

Technology, such as computer networks, all use a universal time – UTC (Coordinated Universal Time). UTC is a global timescale, kept true by an international conglomeration of atomic clocks. This means whether you have a UK based computer network, or a one on the other side of the world, to the technologies – the time is the same.

Most technologies receive this time from an atomic clock source using devices known as NTP servers (after the time protocol: Network Time Protocol). NTP servers take advantage of the atomic clocks onboard GPS satellites so they can not only supply an accurate source of time but they can assure that the time source never drifts.

Other methods of getting an atomic clock source of time include using medium wave transmissions broadcast by places like the UK’s National Physical Laboratory (NPL) or the American National Institute for Standards and Time.

NTP servers ensure that no matter where you are in the world the source of time your computers and technology utilise is always Coordinated Universal Time – no matter what the time of year.



Using Internet Time for Computer Synchronization

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Ensuring your network is synchronized is a vital part of modern computing. Failure to do so, and having different machines telling different times is a recipe for disaster and can cause untold problems, not to mention making it almost impossible to debug or log errors.

And it is not just your own network you need to synchronize to either. With so many networks talking to each other, it is important that all networks synchronize to the same time-scale.

UTC (Coordinated Universal Time) is just such a global timescale. It is controlled by an international constellation of atomic clocks and enables computers all over the world to talk to each other in perfect synchronicity.

But how do you sync to UTC?

The internet is awash with sources of internet time. Most modern operating systems, especially in the Windows flavour, are set up to do this automatically (just by clicking the time/date tab on the clock menu). The computer will then regularly check the time server (usually at Microsoft or NIST, although others can be used) and adjust the computer to ensure its time matches.

Most internet time servers are known as stratum 2 devices. This means they take the time from another device but where does that get the time from?

NTP time servers

The answer is that somewhere on the stratum tree there will be a stratum 1 device. This will be a time server that receives the time direct from an atomic clock source. Often this is by GPS but there are radio referenced alternatives in several countries. These stratum 1 NTP (Network Time Protocol) time servers then provide the stratum 2 devices with the correct time – and its these devices we get our internet time from.

Drawbacks to Internet time

There are several drawbacks to relying on the Internet for time synchronisation. Accuracy is one consideration. Normally, a stratum 2 device will provide ample enough precision for most networks; however, for some users who require high levels of accuracy or deal in a lot of time sensitive transactions a stratum 2 time server may not be accurate enough.

Another problem with internet time servers is that they require an open port in the firewall. Keeping the NTP access on UDP port 123 open all the time could lead to security issues, especially as internet time sources can’t be authenticated or guaranteed.

Using a Stratum 1 NTP Time server

Stratum 1 NTP time servers are easily installed on most networks. Not only will they provide a higher accurate source of time but as they receive the time externally (from GPS or radio) they are highly secure and can’t be hijacked by malicious users or viral software.