NTP Time Servers Keeping Technology Precise

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Atomic clocks are much underrated technologies their development has revolutionised the way we live and work and has made possible technologies that would be impossible without them.

Satellite navigation, mobile phones, GPS, the internet, air traffic control, traffic lights and even CCTV cameras are reliant on the ultra precise timekeeping of an atomic clock.

The accuracy of an atomic clock is incomparable to other time keeping devices as they don’t drift by even a second in hundreds of thousands of years.

But atomic clocks are large sensitive devices that need team of experienced technicians and optimum conditions such as those found in a physics laboratory. So how do all these technologies benefit from the high precision of an atomic clock?

The answer is quite simple, the controllers of atomic clocks, usually national physics laboratories, broadcast via long wave radio the time signals that their ultra precise clocks produce.

To receive these time signals, servers that use the time synchronization protocol NTP (Network Time Protocol) are employed to receive and distribute these timestamps.

NTP time servers, often referred to as network time servers, are a secure and accurate method of ensuring any technology is running accurate atomic clocks time. These time synchronization devices can synchronise single devices or entire networks of computers, routers and other devices.

NTP servers that use GPS signals to receive the time from the atomic clock satellites are also commonly used. These NTP GPS time servers are as accurate as those that receive the time from physics laboratories but use the weaker, line of sight GPS signal as their source.

Technologies that rely on Atomic Clocks (Part 2)

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GPS is not the only technology that is dependent on atomic clocks. The high levels of accuracy that are supplied by atomic clocks are used in other crucial technologies that we take for granted everyday.

Air traffic Control Not only are all aeroplanes and airliners now equipped with GPS to enable pilots and ground staff to know their exact location but atomic clocks are also used by air traffic controllers who need precise and accurate measurements and time between planes.

Traffic Lights and Road Congestion Systems – Traffic lights are another system that relies on atomic clock timing. Accuracy and synchronization is vital for traffic light systems as small errors in synchronization could lead to fatal accidents.

Congestion cameras and other systems such as parking metres also use atomic clocks as a basis of their timekeeping as this prevents any legal issues when issuing penalty notices.

CCTV – Closed circuit television is another large scale user of atomic clocks. CCTV cameras are often used in the fight against crime but as evidence they are ineffective in a court of law unless the timing information on the CCTV camera can be proved to be accurate. Failure to do so could lead to criminals escaping prosecution because despite the identification by the camera, proof that it was at the time and date of the offence can’t be clarified without accuracy and synchronization.

Internet – Many of the applications we now entrust to the internet are only made possible thanks to atomic clocks. Online trading, internet banking and even online auction houses all need accurate and synchronized time.

Imagine taking your savings from your bank account only finding that you can withdraw them again because another computer has a slower clock or imagine bidding on an internet auction site only to have your bid rejected by a bid that came before yours because it was made on a computer with a slower clock.

Using atomic clocks as a source for time is relatively straight forward for many technologies. Radio signals and even the GPS transmissions can be used as a source of atomic clock time and for computer systems, the protocol NTP (Network Time Protocol) will ensure any sized network will be synchronized perfectly together. Dedicated NTP time servers are used throughout the world in technologies and applications that require precise time.

Technologies that rely on Atomic Clocks (Part 1)

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Atomic clocks are the most accurate timekeeping devices known to man. There accuracy is incomparable to other clocks and chronometers in that whilst even the most sophisticated electronic clock will drift by a second every week or two, the most modern atomic clocks can keep running for thousands of years and not lose even a fraction of a second.

The accuracy of an atomic clock is down to what they use as their basis for time measurement. Instead of relying on an electronic current running through a crystal like an electronic clock, an atomic clock uses the hyperfine transition of an atom in two energy states. Whilst this may sound complicated, it is just an unfaltering reverberation that ‘ticks’ over 9 billion times each second, every second.

But why such accuracy really necessary and what technologies are atomic clocks employed in?

It is by examining the technologies that utilise atomic clocks that we can see why such high levels of accuracy are required.

GPS – Satellite navigation

Satellite navigation is a huge industry now. Once just a technology for the military and aviators, GPS satellite navigation is now used by road users across the globe. However, the navigational information provided by satellite navigation systems like GPS is solely reliant on the accuracy of atomic clocks.

GPS works by triangulating several timing signals that are deployed from atomic clocks onboard the GPS satellites. By working out when the timing signal was released from the satellite the satellite navigational receiver can just how far away it is from the satellite and by using multiple signals calculate where it is in the world.

Because of these timing signals travel at the speed of light, just one second inaccuracy within the timing signals could lead to the positing information being thousands of miles out. It is testament to the accuracy of GPS atomic clocks that currently a satellite navigation receiver is accurate to within five metres.

Synchronizing a Computer Network with a Dedicated Network Time Server

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Synchronization is vital for most computer networks. Timestamps are the only reference a computer can use to analyse when and if processes or applications are completed. Synchronized timestamps are also vital for security, debugging and error logging.

Failure to keep a network adequately synchronized can lead to all sorts of problems. Applications fail to commence, time sensitive transactions will fail and errors and data loss will become commonplace.

However, ensuring synchronization no matter the size of network is straight forward and not costly, thank to the dedicated network time server and the time protocol NTP.

Network Time Protocol (NTP)

NTP has been around even longer than the internet but is the most widely used synchronization protocol available. NTP is free to use and makes synchronization very straight forward. It works by taking a single time source (or multiple ones) and distributes it amongst the network. It will maintain high levels of accuracy even when it loses the original time signal and can make judgements on how accurate each time reference.

NTP Time Server

These come in several forms. Firstly there are a number of virtual time servers across the internet that distributes time free of charge. However, as they are internet based a network is taking a risk leaving a firewall port open for this time communication. Also there is no control over the time signal so if it goes down (or becomes unstable or wholly inaccurate) your network can be left without adequate synchronization.

Dedicated NTP time servers use GPS or radio references to receive the time. This is far more secure and as GPS and radio signals like WWVB (from NIST) are generated by atomic clocks there accuracy is second to none.

Because the NTP protocol is hierarchical it also means that only one dedicated time server needs to be used for a network, no matter the size, as other devices on the network can act as time servers after having rece9ved the time from the primary NTP server.

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 Vulnerability of GPS

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An increase in GPS ‘attacks’ has been causing some concern amongst the scientific community.  GPS, whilst a highly accurate and reliable system of transmitting time and positing information, relies on very weak signals that are being hampered by interference from the Earth.

Both unintentional interference such as from pirate radio stations or intentional deliberate ‘jamming’ by criminals is still rare but as technology that can hamper GPS signals becomes more readily available, the situation is expected to get worse.

And while the effects of signal failure of the GPS system may have obvious results for people who use it for navigation (ending up in the wrong location or getting lost) it could have more serious and profound repercussions for the technologies that rely on GPS for time signals.

As so many technologies now rely on GPS timing signals from telephone networks, the internet, banking and traffic lights and even our power grid any signal failure no matter how briefly, could cause serious problems.

The main problem with the GPS signal is that it is very weak and as it comes from space bound satellites, little can be done to boost the signal so any similar frequency being broadcast in a local area can easily drown out GPS.

However, GPS is not the only accurate and secure method of receiving the time from an atomic clock source. Many national physics laboratories from across the globe broadcast atomic clock signals via radio waves (usually long wave). In the USA these signals are broadcast by NIST (National Institute for Standards and Time (known as WWVB) whilst in the UK, it’s MSF signal is broadcast by NPL (National Physical Laboratory).

Dual time servers that can receive both signals are available and are a safer bet for any high technology company that can’t afford to risk losing a time signal.