Category: Time Synchronisation

Choosing a Source of Time for an NTP Synchronization

  |   By

Accurate time is essential in the modern world of internet banking, online auctions and global finance. Any computer network that is involved in global communication needs to have an accurate source of the global timescale UTC (Coordinated Universal Time) to be able to talk to other networks.

Receiving UTC is simple enough. It is available from multiple sources but some are more reliable than others:

Internet Time Sources

The internet is awash with time sources. These vary in reliability and accuracy but some trusted organisations like NIST (National Institute of Standards and Time) and Microsoft. However, there are disadvantages with internet time sources:

Reliability – The demand for internet sources of UTC often means it can be difficult to access them

Accuracy – most internet time servers are stratum 2 devices which means they rely on a source of time themselves. Often errors can occur and many sources of time can be very inaccurate.

Security – Perhaps the biggest issue with internet time sources is the risk they pose to security. To receive a time stamp from across the internet the firewall needs to have an opening to allow the signals to pass through; this can lead to malicious users taking advantage.

Radio Referenced Time Servers.

A secure method of receiving UTC time stamps is available by using a NTP time server that can receive radio signals from labs like NIST and NPL (National Physical Laboratory. Many countries have these broadcasted time signals which are highly accurate, reliable and secure.

GPS Time servers

Another source for dedicated time servers is GPS. The big advantage of a GPS NTP time server is that the time source is available everywhere on the planet with a clear view of the sky. GPS time servers are also highly accurate, reliable and just as secure as radio referenced time servers.

Common Internet Time Synchronisation Issues

  |   By

Keeping the clock on a PC system synchronised is important for many systems, networks and users that need time accuracy for applications and transactions. Nearly everything on a modern computer system is time reliant so when synchronisation fails all sorts of issues can arise from data getting lost and debugging becoming near impossible.

There are several methods of synchronising a computer system’s clock but the majority of them rely on the time synchronisation protocol NTP (Network Time Protocol).

By far the most common method is to make use of the myriad of online NTP time servers that relay the UTC time (Coordinated Universal Time). However, there are many common issues in using internet based time servers – here are some of them:

Can’t access the Internet time server

A common occurrence with Internet time sources is the inability to access them. This can be caused by several reasons:

• Too much traffic trying to access the server
• Website is down
• Your connection is down

The time from the time server is innacuurate

Most online sources of time are what are known as stratum 2 time servers. This means they get their time from another time server (stratum 1) that it connected to an atomic clock (stratum 0). If there is an error with the stratum 1 device the stratum 2 device will be wrong (and every device that is trying to get the time from it).

The time server is leading to security problems with the firewall

Another common problem caused by the fact that all online time servers need access through your firewall. Unfortunately this gives the opportunity for malicious users to make use of this back door into your system.

Eliminating Time Server Issues

Internet time sources are neither guaranteed to be accurate, reliable or secure so for any serious time synchronisation requirements an external source of time should be used. NTP time servers that plug into a network and receive the time from GPS or radio sources are a much more secure and reliable alternative. These NTP servers are also highly secure as they do not operate across the Internet.

GPS as a Timing Reference for NTP servers

  |   By

The GPS system is familiar to most people. Many cars now have a GPS satellite navigation device in their cars but there is more to the Global Positioning System than just wayfinding.

The Global Positioning System is a constellation of over thirty satellites all spinning around the globe. The GPS satellite network has been designed so that at any point in time there is at least four satellites overhead – no matter where you are on the globe.

Onboard each GPS satellite there is a highly precise atomic clock and it is the information from this clock that is sent through the GPS transmissions which by triangulation (using the signal from multiple satellites) a satellite navigation receiver can work out your position.

But these ultra precise timing signals have another use, unbeknown to many users of GPS systems. Because the timing signals from the GPS atomic clocks are so precise, they make a good source of time for synchronising all sorts of technologies – from computer networks to traffic cameras.

To utilise the GPS timing signals, a GPS time server is often used. These devices use NTP (Network Time Protocol) to distribute the GPS timing source to all devices on the NTP network.

NTP regularly checks the time on all the systems on its network and adjusts it accordingly if it has drifted to what the original GPS timing source is.

As GPS is available anywhere on the planet it provides a really handy source of time for many technologies and applications ensuring that whatever is synchronised to the GPS timing source will remain as accurate as possible.

A single GPS NTP server can synchronize hundreds and thousands of devices including routers, PCs and other hardware ensuring the entire network is running perfectly coordinated time.

A Guide to Network Time Protocol

  |   By

NTP (Network Time Protocol) is perhaps the oldest and most commonly used protocol employed by computers and yet it is probably the least understood.

NTP is used by nearly all computers, networks and other devices that are involved in communicating across the internet or internal networks. It was developed in the very earliest stages of the internet when it became evident that some method of ensuring accuracy over distance was required.

The protocol works by selecting a single time source, of which NTP has the ability to establish the accuracy and reliability of, which it then distributes around every device on the NTP network.

Each device is regularly checked against this reference clock and adjusted if any drift is noticed. A version of NTP is now deployed with virtually every operating system allowing any machine to be synchronized to a single time source.

Obviously if every network in the world selected a different time source as its reference, the reason for of all this synchronization would be lost.

Fortunately, a global timescale based on an international consortium of atomic clocks has been developed to provide a single time source for the purposes of global synchronisation.

UTC (Coordinated Universal Time) is used by computer networks worldwide as a time reference which means any device that is synchronised to UTC with NTP will in effect be synchronised with every network that uses UTC as its base time.

There are many different methods that NTP can access UTC time. The internet is a common location although this does provide security and firewall issues. A more secure (and accurate) method is to use a dedicated NTP time server that takes the time from external sources such as the GPS network (GPS works by broadcasting an atomic clock timestamp that is easily converted to UTC by a NTP server).

With NTP, a dedicated time server and access to UTC an entire network can be synchronised to within a few milliseconds of the universal time providing a secure and accurate network that can operate in complete synchronicity with other networks across the globe.

Synchronizing a PC to an Atomic Clock

  |   By

Atomic clocks are without doubt the most accurate time pieces on the face of the planet. In fact the accuracy of an atomic clock in incomparable to any other chronometer, watch or clock.

While an atomic clock will not lose even a second in time in thousands upon thousands of years, you’re average digital watch will perhaps lose a second in just a few days which after a few weeks or months will mean your watch is running slow or fast by several minutes.

The same can also be said for the system clock that controls your computer the only difference is that computers rely even more heavily on time than we ourselves do.

Nearly everything a computer does is reliant on timestamps, from saving work to performing applications, debugging and even emails are all reliant on timestamps which can be a problem if the clock on your computer is running too fast or slow as errors can quite often occur, especially if you are communicating with another computer or device.

Fortunately, most PCs are easily synchronized to an atomic clock meaning they can be accurate as these powerful time keeping devices so any tasks performed by your PC can be in perfect synchronicity with whatever device you are communicating with.

In most PC operating systems an inbuilt protocol (NTP) allows the PC to communicate with a time server that is connected to an atomic clock. In most versions of Windows this is accessed through the date and time control setting (double clicking the clock in the bottom right).

However, for business machines or networks that require secure and accurate time synchronization, online time servers are just not secure or accurate enough to ensure your network is not vulnerable to security flaws.

However, NTP time servers that receive the time direct from atomic clocks are available that can synchronize entire networks. These devices receive a broadcasted timestamp distributed by either national physics laboratories or via the GPS satellite network.

NTP servers enable entire networks to all have exactly synchronized time which is as accurate and secure as is humanly possible.

Synchronizing a Computer Network with a Dedicated Network Time Server

  |   By

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

  |   By

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

  |   By

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.

Quantum Atomic Clocks The precision of the future

  |   By

The atomic clock is not a recent invention. Developed in the 1950’s, the traditional caesium based atomic clock has been providing us with accurate time for half a century.

The caesium atomic clock has become the foundation of our time – literally. The International System of Units (SI) define a second as a certain number of oscillations of the atom caesium and atomic clocks govern many of the technologies that we live with an use on a daily basis: The internet, satellite navigation, air traffic control and traffic lights to name but a few.

However, recent developments in optical quantum clocks that use single atoms of metals like aluminium or strontium are thousands of times more accurate than traditional atomic clocks. To put this in perspective, the best caesium atomic clock as used by institutes like NIST (National Institute for Standards and Time) or NPL (National Physical Laboratory) to govern the world’s global timescale UTC (Coordinated Universal Time), is accurate to within a second every 100 million years. However, these new quantum optical clocks are accurate to a second every 3.4 billion years – almost as long as the earth is old.

For most people, their only encounter with an atomic clock is receiving its time signal is a network time server or NTP device (Network Time Protocol) for the purposes of synchronising devices and networks and these atomic clock signals are generated using caesium clocks.

And until the world’s scientists can agreed on a single atom to replace caesium and a single clock design for keeping UTC, none of us will be able to take advantage of this incredible accuracy.

Atomic Clocks Now Doubled in Precision

  |   By

As with the advance of computer technology that seems to exponentially increase in capability every year, atomic clocks too seem to increase dramatically in their accuracy year on year.

Now, those pioneers of atomic clock technology, the US National Institute of Standards Time (NIST), have announced they have managed to produce an atomic clock with accuracy twice that of any clocks that have gone before.

The clock is based in a single aluminium atom and NIST claim it can remain accurate without losing a second in over 3.7 billion years (about the same length of time that life has existed Earth).

The previous most accurate clock was devised by the German Physikalisch-Technische Bundesanstalt (PTB) and was an optical clock based on a strontium atom and was accurate to a second in over a billion years. This new atomic clock by NIST is also an optical clock but is based on aluminium atoms, which according to NIST’s research with this clock, is far more accurate.

Optical clocks use lasers to hold atoms still and differ to the traditional atomic clocks used by computer networks using NTP servers (Network Time Protocol) and other technologies which are based on fountain clocks. Not only do these traditional fountain clocks use Caesium as their time keeping atom but instead of lasers they use super-cooled liquids and vacuums to control the atoms.

Thanks to work by NIST, PTB and the UK’s NPL (National Physical Laboratory) atomic clocks continue to advance exponentially, however, these new optical atomic clocks based on atoms like aluminium, mercury and strontium are a long way from being used as a basis for UTC (Coordinated Universal Time).

UTC is governed by a constellation of caesium fountain clocks that while still accurate to a second in 100,000 years are by far less precise than these optical clocks and are based on technology over fifty years old. And unfortunately until the world’s science community can agree on an atom and clock design to be used internationally, these precise atomic clocks will remain a play thing of the scientific community only.