MSF Downtime on March 11

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The National Physical Laboratory has announced scheduled maintenance this week (Thursday) meaning the MSF60kHz time and frequency signal will be temporarily turned off to allow the maintenance to be conducted in safety at the Anthorn radio Station in Cumbria.

Normally these scheduled maintenance periods only last a few hours and should not cause any disturbance to anybody relying on the MSF signal for timing applications.
NTP (Network Time Protocol) is well suited to these temporary losses of signal and little if no drift should be experienced by any NTP time server user.

However, there are some high level users of network time servers or may have concerns on the accuracy of their technology during these scheduled periods of no signal. There is another solution for ensuring a continuous, secure and equally accurate time signal is always being used.

GPS, most commonly used for navigation and wayfinding it actually an atomic clock based technology. Each of the GPS satellites broadcasts a signal from their onboard atomic clock which is used by satellite navigation devices that work out the location through triangulation.

These GPS signals can also be received by a GPS NTP time server. Just as MSF or other radio signal time servers receive the external signal from the Anthorn transmitter, GPS time servers can receive this accurate and external signal from the satellites.

Unlike the radio broadcasts, GPS should never go down although it can sometimes be impractical to receive the signal as a GPS antenna needs a clear view of the sky and therefore should preferably be on the roof.

For those wanting to make doubly sure there is never a period when a signal is not being received by the NTP server, a dual time server can be used. These pick up both radio and GPS transmissions and the onboard NTP daemon calculates the most accurate time from them both.

The Effect of Solar Flares on GPS

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Forthcoming space weather may affect GPS devices including satellite navigation and NTP GPS time servers.

Whilst many of us have had to cope with some extreme weather last winter, further storms are on their way – this time from space.

Solar flares are a regular occurrence on the surface of the sun. Whilst scientists are not completely sure what causes them we know two things about solar flares: – they are cyclical – and are related to sunspot activity.

For that last eleven years the sun’s sunspot activity – small dark depressions that appear on the surface of the sun – has been very minimal. But this eleven year cycle has come to an end and there has been a rise in sun spots at the end of last year meaning 2010 will be a bumper year for both sunspots and solar flares.

But there is no need to worry about becoming toasted by solar flares as these bursts of hot gases that flare from the sun never get far enough to reach the Earth, however, they can effect us in different ways.

Solar flares are bursts of energy and as such emit radiation and high energy particles. On earth, we are protected by these blasts of energy and radiation by the earth’s magnetic field and ionosphere, however, satellite communications are not and this can lead to trouble.

Whilst the effect of solar flare radiation is very weak, it can slow down and reflect radio waves as they travel through the ionosphere towards Earth. This interference can cause GPS satellites in particular extreme problems as they are reliant on accuracy to provide navigational information.

While the effects of solar flares are mild, it is possible GPS devices will encounter brief periods of no signal and also the problem of inaccurate signals meaning positing information may become unreliable.

This will not just affect navigation either as the GPS system is used by hundreds and thousands of computer networks as a source of reliable time.

Whilst most dedicated GPS time servers should be able to cope with periods of instability without losing precision, for worried network administrators not wanting to go into work to find their systems have crashed because of a lack of synchronisation may want to consider using a radio referenced Network time server that uses broadcast transmission such as MSF or WVBB.

Dual NTP time servers (Network Time Protocol) are also available that can receive both radio and GPS, ensuring a source of time is always constantly available.

Why a GPS Time Server is the Number One Choice for Time Synchronization

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When it comes to synchronizing a computer network there are several choice to ensure each device is running the same time. NTP (Network Time Protocol) is the preferred choice of time synchronization protocols but there are a multitude of methods in how NTP receives the time.

The NTP Daemon is installed on most operating systems such as windows and applications such as Windows Time are quite capable of receiving a source of UTC time (Coordinated Universal Time) from across the internet.

UTC time is the preferred time source used by computer networks as it is kept true by atomic clocks. UTC, as the name suggests, is also universal and is used by computer networks all over the world as a source to synchronize too.

However, internet sources of UTC are to recommended for any organisation where security and accuracy are a concern. Not only can the distant from host (internet time server) to the client (your computer network) can never be accurately measured leading to a drop in precision. Furthermore, any source of internet time will need access through the firewall (usually through the UDP 123 port). And by leaving this port open, malicious users and hackers can take advantage and gain access to the system.

Dedicated NTP time servers are a better solution as they receive the time from an external source. There are really two types of NTP server, the radio reference time server and the GPS time server.
Radio reference time servers use signals broadcast by places like NPL (National Physical Laboratory in the UK) or NIST (National Institute of Standards and Time). While these signals are extremely accurate, precise and secure they are affected by regular maintenance on the transmitters that broadcast the signal. Also being long wave they are vulnerable to local interference.

GPS time servers on the other hand receive the time directly from GPS satellites. This GPS time is easily converted to UTC by NTP (GPS time is UTC – 17 seconds exactly as no leap seconds have been added.) As the GPS signal is available everywhere on the earth 24 hours a day, 365 days a week, there is never a risk of a loss of signal.
A single dedicated GPS time server can synchronize a computer network of hundreds, and even thousands of machines to within a few of milliseconds of UTC time.

2038 The Next Computer Time Bug

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Remember the turn of the millennium. Whilst many of us were counting down the seconds until midnight, there were network administrators across the globe with their fingers crossed hoping their computer systems will still be working after the new millennium kicked in.

The millennium bug was the result of early computer pioneers designing systems with only two digits to represent the time as computer memory was very scarce at the time. The problem didn’t arise because of the turn of the millennium, it arose because it was the end of the century and two digit year flicked around to 00 (which the machines assume was 1900)

Fortunately by the turn of the millennium most computers were updated and enough precautions were taken that meant that the Y2K bug, as it became known, didn’t cause the widespread havoc it was first feared.

However, the Y2K bug is not the only time related problem that computer systems can be expected to face, another problem with the way computers tell the time has been realised and many more machines will be affected in 2038.

The Unix Millennium Bug (or Y2K38) is similar to the original bug in that it is a problem connected with the way computers tell the time. The 2038 problem will occur because most machines use a 32 bit integer to calculate the time. This 32 bit number is set from the number of seconds from 1 January 1970, but because the number is limited to 32 digits by 2038 there will be no more digits left to deal with the advance of time.

To solve this problem, many systems and languages have switched to a 64-bit version, or supplied alternatives which are 64-bit and as the problem will not occur for nearly three decades there is plenty of time to ensure all computer systems can be protected.

However, these problems with timestamps are not the only time related errors that can occur on a computer network. One of the most common causes of computer network errors is lack of time synchronization. Failing to ensure each machine is running at an identical time using a NTP time server can result in data being lost, the network being vulnerable to attack from malicious users and can cause all sorts of errors such as emails arriving before they have been sent.

To ensure your computer network is adequately synchronized an external NTP time server is recommended.

A Guide to Using a GPS Clock

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The Global Positioning System much loved by drivers, pilots and sea-farers as a method of finding location offers much more than just satellite navigation information. The GPS system work by using atomic clocks that broadcast signals that are then triangulated by the computer in a satellite navigation system.

Because these atomic clocks are highly accurate and don’t drift by as much as a second even in a million years, they can be utilised as a method of synchronizing computer systems. GPS time, the time relayed by the GPS atomic clocks, is not strictly speaking the same as UTC (Coordinated Universal Time), the world’s global timescale, but as they are both based on International Atomic Time it can easily be converted. (GPS time is actual 17 seconds slower than UTC as there have been 17 leap seconds added to the global timescale since the GPS satellites where sent in to orbit).

A GPS clock is a device that receives the GPS signal and then translates it into the time. Most GPS clocks are dedicated time servers too as there is little point in receiving the exact time if you are to do nothing with it. GPS time servers use the protocol NTP (Network Time Protocol) which is one of the internet’s oldest protocols and designed to distribute timing information across a network.

A GPS clock, or GPS time server works by receiving a signal directly from the satellite. This unfortunately means the GPS antenna has to have a clear view of the sky to receive a signal. The time is then distributed from the time server to all devices on the network. The time on each device is regularly checked by NTP and if differs to the time from the GPS clock then it is adjusted.

Setting up a GPS clock for time synchronization is relatively easy. The time server (GPS clock) are often designed to fill a 1U space on a server rack. This is connected to the GPS antenna (usually on the roof) via a length of coax cable. The server is connected to the network and once it has locked on to the GPS system it can be set to begin synchronizing the network.

What Atomic Clocks Have Done for Us

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Atomic clocks, as many people know they are highly accurate devices but the atomic clock is one of the most important inventions of the last 50 years and has given rise to numerous technologies and applications that have completely revolutionized our lives.

You may think how a clock could be so important regardless of how accurate it is, however, when you consider that precision, that a modern atomic clock doesn’t lose a second in time in tens of millions of years when compared to the next best chronometers – electronic clocks – that can lose a second a day you get to realise just how accurate they are.

In fact, atomic clocks have been crucial in identifying the smaller nuances of our world and the universe. For instance we have for millennia assumed that a day is 24 hours long but in fact, thanks to atomic clock technology we now know that the length of each day slightly differs and in general the earth’s rotation is slowing down.

Atomic clocks have also been used to accurately measure the earth’s gravity and have even proved Einstein’s theories of how gravity can slow time by accurately measuring the difference in the passing of time at each subsequent inch above the earth’s surface. This has been crucial when it comes to placing satellites in orbit as time passes quicker that high above the earth than it does on the ground.

Atomic clocks also form the basis for many of the technologies that we employ in our day to day lives. Satellite navigation devices rely on atomic clocks in GPS satellites. Not only do they have to take into account the differences in time above the orbit but it as sat navs use the time sent from the satellites to triangulate positions, a one-second inaccuracy would see navigational information inaccurate by thousands of miles (as light travels nearly 180,000 miles every second).

Atomic clocks are also the basis for the world’s global timescale – UTC (Coordinated Universal Time), which is utilised by computer networks throughout the world. Time synchronization to an atomic clock and UTC is relatively straight forward with a NTP time server. These use the time signal from the GPS system or special transmissions broadcast from large scale physics labs and then distribute it across the internet using the time protocol NTP.

Reported GPS Fears Should Not Affect Time Synchonisation

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Following recent media reports on the lack of investment in the USA’s Global Navigation Satellite System – GPS (Global Positioning System) and the potential failure of navigational receivers in recent years, time synchronisation specialists, Galleon Systems, would like to ensure all their customers that any failure of the GPS network will not affect current GPS NTP time servers.

Recent media reports following a study by the US government’s accountability office (GAO), that concluded mismanagement and a lack of investment meant some the current number of 31 operational satellites may fall to below 24 at times in 2011 and 2012 which would hamper its accuracy.

However, the UK’s National Physical Laboratory are confident that any potential problems of the GPS navigation facilities will not affect timing information utilised by GPS NTP servers.

A spokesman for the UK’s National Physical Laboratory confirmed that timing information should be unaffected by any potential future satellite failure.

“There is estimated to be a 20% risk that in 2011-2012 the number of satellites in the GPS constellation could drop below 24 at times.

“If that were to happen, there could be a slight reduction in the position accuracy of GPS receivers at some periods, and in particular they might take longer to acquire a fix in some locations when first powered up. However, even then the effect would be a degradation of performance, rather than complete failure to operate.

“A GPS timing receiver is unlikely to be affected significantly since, once it has determined its position when turned on, every satellite it observes provides it with useful timing information. A small reduction in the number of satellites in view should not degrade its performance much.”

Computers, Communications, Atomic Clocks and the NTP Server

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Time synchronisation on computer networks is often conducted by the NTP server. NTP time servers do not generate any timing information themselves but are merely methods of communicating with an atomic clock.

The precision of an atomic clock is widely talked about. Many of them can maintain time to nanosecond precision (billionths of a second) which means they won’t drift beyond a second in accuracy in hundreds of millions of years.

However, what is less understood and talked about is why we need to have such accurate clocks, after-all the traditional methods of keeping time such as mechanical clocks, electronic watches and using the rotation of the Earth to keep track of the days has proved reliable for thousands of years.

However, the development of digital technology over recent years has been nearly solely reliant on the ultra high precision of an atomic clock. One of the most widely used applications for atomic clocks is in the communications industry.

For several years now telephone calls taken in most industrialized countries are now transmitted digitally. However, most telephone wires are simply copper cables (although many telephone companies are now investing in fibre optics) which can only transmit one packet of information at a time. Yet telephone wires have to carry many conversations down the same wires at the same time.

This is achieved by computers at the exchanges switching from one conversation to another thousands of times every second and all this has to be controlled by nano-second precision otherwise  the calls will become out of step and get jumbled – hence the need for. Atomic clocks; mobile phones, digital TV and Internet communications use similar technology.

The accuracy of atomic clocks is also the basis for satellite navigation such as GPS (global positioning system). GPS satellites contain an onboard atomic clock that generates and transmits a time signal. A GPS receiver will receive four of theses signals and use the timing information to work out how long the transmissions took to reach it and therefore the position of the receiver on Earth.

Current GPS systems are accurate to a few metres but to give an indication of how vital precision is, a one second drift of a GPS clock could see the GPS receiver be inaccurate by over 100 thousand miles (because of the  huge distances light and therefore transmissions take in one second).

Many of these technologies that depend on atomic clocks utilise NTP servers as the preferred way to communicate with atomic clocks making the NTP time server one of the most crucial pieces of equipment in the communication industries.

Bringing Atomic Clock Precision to your Desktop

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Atomic clocks have been a huge influence on our modern lives with many of the technologies that have revolutionised the way we live our lives relying on their ultra precise time keeping abilities.

Atomic clocks are far different to other chronometers; a normal watch or clock will keep time fairly accurately but will lose second or two each day. An atomic clock on the other hand will not lose a second in millions of years.

In fact it is fair to say that an atomic clock doesn’t measure time but is the foundations we base our perceptions of time on. Let me explain, time, as Einstein demonstrated, is relative and the only constant in the universe is the speed of light (though a vacuum).

Measuring time with any real precision is therefore difficult as even the gravity on Earth skews time, slowing it down. It is also almost impossible to base time on any point of reference. Historically we have always used the revolution of the earth and reference to the celestial bodies as a basis for our time telling (24 hours in a day = one revolution of the Earth, 365 days = one revolution of the earth around the Sun etc).

Unfortunately the Earth’s rotation is not an accurate frame of reference to base our time keeping on. The earth slows down and speeds up in its revolution meaning some days are longer than others.

Atomic clocks
however, used the resonance of atoms (normally caesium) at particular energy states. As these atoms vibrate at exact frequencies (or an exact number of times) this can be used as a basis for telling time. So after the development of the atomic clock the second has been defined as over 9 billion resonance ’ticks’ of the caesium atom.

The ultra precise nature of atomic clocks is the basis for technologies such as satellite navigation (GPS), air traffic control and internet trading. It is possible to use the precise nature of atomic clocks to synchronise computer networks too. All that is needed is a NTP time server (Network Time Protocol).
NTP servers receive the time from atomic clocks via a broadcast signal or the GPS network they then distribute it amongst a network ensuring all devices have the exact same, ultra precise time.

Security and Synchronisation

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Security is often the most worried about aspect of running a computer network. Keeping unwanted users out whilst allowing freedom for users to access network applications is a full time job. Yet many network administrators fail to pay any heed to one of the most crucial aspects of keeping a network secure – time synchronisation.

Time synchronisation is not just important but it is vital in network security and yet it is staggering how many network administrators disregard it or fail to have their systems properly synchronised.

Ensuring the same and correct time (ideally UTC – Coordinated Universal Time) is on each network machine is essential as any time delays can be an open door for hackers to slip in undetected and what is worse if machines do get hacked are not running the same time it can be near impossible to detect, repair and get the network back up and running.

Yet time synchronisation is one of the simplest of tasks to employ, particularly as most operating systems have a version of the time protocol NTP (Network Time Protocol).

Finding an accurate time server can sometimes be problematic particularly if the network is synchronised across the internet as this can raise other security issues such as having an open port in the firewall and a lack of possible authentication by NTP to ensure the signal is trusted.

However, an easier method for time synchronisation, being both accurate and secure, is to use a dedicated NTP time server (also known as network time server). An NTP server will take a time signal direct from GPS or from the national time and frequency radio transmissions put out by organisations such as NIST or NPL.

By using a dedicated NTP server the network will become a lot securer and if the worst does happen and the system does fall victim to malicious users then having a synchronised network will ensure it is easily solvable.