The Time According to Cumbria Using the UKs MSF Time and Frequency Signal

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Getting an accurate source of time for computer networks and other technologies is increasingly becoming more important. As technologies advance and global communications mean that we are just as liable to communicate with technology across the other side of the planet as we are at home.

The need for accurate time is therefore essential if you wish to prevent time sensitive applications on your network failing or to avoid debugging problems – not too mention keeping your system secure.

NTP time servers (Network Time Protocol) are common devices that many computer networks use to provide a source of accurate time as NTP is able to ensure entire networks are synchronised to just a few milliseconds to the time reference.

The time reference that NTP servers use can come from several locations:

  • The internet
  • GPS satellite
  • And National Physical Laboratories

In the UK, the National Physical Laboratory (NPL) produce a time signal that can be received by radio referenced NTP time servers. This used to be broadcast from rugby in central England but in recent years the transmission has been moved to Cumbria.

The Cumbrian signal, known as MSF, is broadcast from Anthorn with a signal strength of 100 microvolts per metre at a distance of 1000 km. This should mean that the signal is available everywhere in the UK; however, this is not strictly the case as many MSF clocks and time servers can run into trouble when first trying to receive this atomic clock generated signal.

However, a simple checklist should ensure that no matter what your location you should be able to receive a signal to your MSF clock or NTP time server:

  • Check the power. Perhaps the most common problem ensure the battery is inserted and if the clock uses both mains power and a battery, remember to switch the mains power on. It can take quite a few minutes for the clock to pick up the MSF signal, so be patient.
  • Try rotating the clock or time server. As the MSF signal is long wave the antenna needs to be perpendicular to the signal for best reception.
  • If all else fails move the clock or time server to a different location. The signal can be blocked by local interference from electrical and mechanical devices.

* Note the MSF signal is down for scheduled maintenence on Tuesday 9 September 2010 from 10:00 BST to 14:00 BST

 

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.



GPS Time Servers Precise Time all the Time

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Keeping computer networks accurate and synchronised can’t be emphasised highly enough. Accurate time is essential in the modern global economy as computer networks across the globe are required to constantly talk to each other.

Failing to ensure a network is accurate and precise can lead to headache after headache: transactions can fail, data can get lost, and error logging and debugging can be virtually impossible.

Atomic Clocks

Atomic clocks form the basis of the global timescale – UTC (Coordinated Universal Time). UTC is used across the globe by technology and computer networks enabling the entire commercial and technological world to communicate in synchronicity together.

But as atomic clocks are highly technical (and expensive) pieces of hardware that require a team of technicians to control – where do people get a source of such accurate time?

The answer is quite simple; atomic clock timestamps are transmitted by physics laboratories and are avlaible from a whole host of sources – kept accurate by the time software NTP (Network Time Protocol).

NTP Time Servers

The most common location for sources of atomic clock generated UTC is the internet. A whole host of online time servers are avlaible for synchronisation but these can vary in their accuracy and precision. Furthermore, using a source of internet time can create vulnerabilities in the network as the firewall has to allow these timestamps through and therefore can be utilised by viruses and malicious software.

By far the most secure and accurate method of receiving a source of atomic clock generated time is to utilise the GPS network (Global Positioning System).

GPS time servers are unique in that as long as there is a clear view of the sky they can receive a source of time – anywhere on the globe, 24 hours-a-day, 365 days a year.

They are also highly accurate with a single GPS NTP time server able to synchronise entire networks to just a few milliseconds of UTC.

How accurate does NTP Synchronisation need to be?

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Computers advance at a remarkable rate; in effect computers double in power, speed and memory every five years, and with such advances in technology many people assume that the clocks that control the time of a computer are just as powerful.

However, nothing could be further from the truth; most system clocks are crude crystal oscillators that are prone to drift, which is why computer time synchronisation is so important.

In modern computing, nearly every aspect of managing a network is reliant on time. Timestamps are the only frame of reference a computer has to ascertain if an event has occurred, is due to, or shouldn’t occur.

From debugging, to conducting time sensitive transactions over the internet, accurate time is essential. But how accurate does it have to be?

Coordinated Universal Time

Coordinated Universal Time (UTC) is a global timescale derived from atomic clocks. UTC was developed to allow technological devices, such as computer networks, to communicate with a single time.

Most computer networks use time servers governed by NTP (Network Time Protocol) to distribute UTC across the network. For most applications, accuracy to within a few hundred milliseconds is sufficient – but achieving this accuracy is where the difficulty lies.

Getting an accurate source of time

There are several options for synchronizing a network to UTC. Firstly, there is the internet. The internet is awash with time servers that proclaim to supply an accurate source of UTC. However, surveys of these online sources of time indicate that many of them are wholly inaccurate being seconds, minutes and even days out.

And even the most accurate and respected sources from NIST (National Institute of Standards and Time) and Microsoft, can vary depending on the distance your network is away.

Dedicated Time servers

Dedicated NTP time servers use a more direct approach to achieve accurate synchronisation. Using atomic clocks, either from the GPS satellite network or from physics laboratories (like NIST and the UKs NPL); the time is beamed directly to the NTP time server that is connected to the network.

Because dedicated devices like this receive the time directly from atomic clocks they are incredibly accurate, enabling the entire network to be synchronised to within just a few milliseconds of NTP.

Solar Flares and the Vulnerability of GPS

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Whilst GPS is commonly associated with satellite navigation and wayfinding, many technologies and computer networks rely on the GPS satellite system for a source of accurate time.

GPS time servers utilise the onboard atomic clocks of the global positing satellites and use this stable and accurate time source as a basis for their NTP synchronisation (Network Time Protocol)

GPS has become the preferred source of atomic clock time for many network operators. There are other methods where UTC (Coordinated Universal Time) can be used; radio signals and across the internet to name but two sources, but none is as secure or readily available as GPS.

Unlike radio signals, GPS is available everywhere on the planet, is never down for scheduled maintenance and is not commonly vulnerable to interference. It also doesn’t have any security implications like connecting across an internet firewall to an online time server can.

However, this doesn’t mean GPS is completely invulnerable as recent news reports have suggested.
It has been recently reported that a sunspot (sunspot 1092) the size of the Earth has flared up and a massive coronal ejection (solar flare), described in the press as a “solar tsunami” which was suggested to be large enough to satellites and wreck power and communications grids.

Solar activity, such as sunspots and solar flares (ejected hot plumes of plasma and radiation from the sun), have long been known to be able to damage and even disable satellites.

GPS is particularly vulnerable because of the high orbits of geostationary satellites (some 22,000 miles up) this leaves them unprotected by the earth’s magnetic field.

However, following the recent solar activity there has been no reported damage to the GPS system but as so many people rely on satellite navigation and GPS time for NTP servers could a future solar storm lead to havoc on Earth?

Well the short answer is yes; GPS satellites have been in orbit for several decades and while redundant satellites were introduced into the system many have been used up due to previous failures and it would only take a couple of disabled satellite to cause real problems for the network.

Fortunately, help is at hand as the Europeans, Russians and Chinese are all working on their own GPS equivalents which should work hand-in-hand with the American GPS network allowing GPS receivers to pick and choose from all four GNSS networks (Global Navigational Satellite Systems) ensuring that even if a really violent solar storm hits in the future there will be more than enough geo stationary satellites to ensure no loss of signal.

Using Windows 7 and Reasons Your Network Still Needs an NTP Server

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Time synchronisation becomes more and more relevant as we become more dependent on the internet. With so many time sensitive transactions conducted across the globe, from banking and commerce to sending emails, the correct and accurate time is vital in preventing errors and ensuring security.

Increasingly, more and more people are relying on sources of internet time especially with many of the modern flavours of Microsoft’s Windows such as Windows 7 having NTP and time synchronisation abilities already installed.

Windows 7 and Time Synchronisation

Windows 7 will, straight out of the box, attempt to find a source of internet time; however, for a networked machine this does not necessarily mean the computer will be synchronised accurately or securely.

Internet time sources can be wholly unreliable and unsecure for a modern computer network. Internet time has to come through the firewall and as a gap is left for these time codes to come through, malicious software can take advantage of this firewall hole too.

Not only can the accuracy of these devices vary depending on the distance away your network is but also an internet time source very rarely comes direct from an atomic clock.

In fact, most internet time sources are known as stratum 2 devices. This means they connect to another device – a stratum 1 device – namely a NTP time server which gets the time directly from the clock and transmits it to the stratum 2 device.

Stratum 1 NTP time servers

For true accuracy and security, there is no replacement for your network’s own stratum 1 NTP server. Not only are these devices secure, receiving a time source externally to the firewall (often using GPS) but also they receive these signals direct from atomic clocks (The GPS satellite that transmits this signal has an onboard atomic clock that generates the time.

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.

MSF Downtime No Signal 26th and 27th July

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The UK’s time and frequency signal MSF, provided by the National Physical Laboratory out of Cumbria, will be down for essential maintenance on 26 and 27 July.

The unplanned downtime is to allow essential maintenance to be carried out in safety. The MSF transmitter will stop broadcasting the MSF signal on 26 and 27 July between 08.00 and 20.00 (BST – 07:00 GMT/UTC) although it is possible the maintenance may be finished ahead of schedule in which case the signal will be turned on earlier.

Future maintenance is scheduled for the following times when the signal will also be turned off:

• 9 September 2010 from 10:00 BST to 14:00 BST
• 9 December 2010 from 10:00 UTC to 14:00 UTC
• 10 March 2011 from 10:00 UTC to 14:00 UTC

Problems for Time Synchronisation

Generally, most NTP time servers should be able to maintain a stable time during these brief outages and users of MSF time synchronisation devices should not experience any difficulties with the lack of MSF signal.

However, those users who require high levels of accuracy and reliability and find the MSF outages affect them should perhaps look to a GPS NTP server.

GPS time servers receive their time signals from the GPS network which is available 24 hours a day, 365 days a year and never experiences any outages.

MSF Downtime – No Signal 26/27 July

NTP Servers versus Internet Time What is the best method for Accurate Time?

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Accurate and reliable time is highly important and as networks and the internet gets faster and faster – accuracy becomes even more essential.

Computers internal clock systems are nowhere near accurate enough for many networked tasks. As simple quartz chronometers they will drift, by as a much as a second which perhaps wouldn’t be a problem if it wasn’t for the fact that all the clocks on the network may drift at different rates.

And as the world becomes more global, ensuring computer networks can talk to each other is also important meaning that synchronisation to the global timescale UTC (Coordinated Universal Time) is now a prerequisite for most networks.

Methods of Synchronisation

There are currently, only two methods for getting truly accurate and reliable time:

  • Use of an internet based time server from places like NIST (National Institute of Standards and Time) or Microsoft.
  • Use of a dedicated NTP time server – that receives external time sources such as from GPS

There are advantages and disadvantages to both types of sources – but which method is best?

Internet Time

Internet time has one great advantage – it is often free. However there are disadvantages to using an internet tie source. The first is distance. Distance across the internet can have a dramatic effect and as the internet gets quicker the distance has an even bigger effect meaning that accuracy become more tenuous.

Another disadvantage of internet time is the lack of authentication and the security risk it poses. Authentication is what the time protocol NTP (Network Time Protocol) uses to establish the true identity of a time source.

Furthermore, an internet time source can only be accessed through a network firewall so a UDP port has to be kept open providing a possible entrance for software nasties or malicious users.

NTP Time Server

NTP time servers on the other hand are dedicated devices. They retrieve a source of UTC externally to the firewall from either GPS or a long wave radio transmission. These come direct from atomic clocks (in the cased of GPS the atomic clock is onboard the satellite) and so can’t be hijacked by malicious users or viruses.

NTP servers are also far more accurate and are not impinged by distance meaning that a network can have millisecond accuracy all the time.

Time to get accurate Atomic clock time servers for computer networks

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Accurate and precise time is increasingly becoming a necessity for computer systems. From corporate networks to public service technologies such as ATMs, traffic lights or CCTV cameras – precise time is what keeps them ticking.

Inaccurate or unsynchronised time is the root cause for many technology breakdowns and failures.  For instance, failing to synchronize a traffic lights system can lead to all sorts of confusion of the lights change at the wrong time – and the consequences for systems belonging to industries such as air traffic control could be even worse.

And even a standard computer network such as those used in most offices requires accurate synchronisation to prevent errors, enable debugging and to ensure the system is secure.

Most system administrators are now aware of the importance of accurate and precise time synchronisation but getting a source of accurate time is often where many people make mistakes.

Many network administrators are aware of the time protocol NTP (Network Time Protocol) which is used to ensure accurate synchronisation between computers.

However, many administrators make the mistake of using a source of time from across the internet to distribute with NTP – a common pitfall that can have disastrous consequences.

The internet is not the best source of tine. While it is true, many online NTP servers are available as a source of atomic time or UTC (Coordinated Universal Time) but are they accurate. The truth is it is almost impossible to know. Internet time sources can be affected by the distance of the client (the network) from the time source – it also can’t be authenticated by NTP.

Even more important, internet time sources operate through the firewall which can allow the time signal to be hijacked by malicious programs.

The only secure and accurate method of synchronising a computer network or other technology system is to use an NTP server. These devices receive an external atomic clock time signal often by GPS or even by radio transmissions.

These signals are come direct from atomic clocks so are highly accurate they also can’t be hijacked as they are not connected to the internet.