New Technologies and the Growing Importance of Time Synchronisation

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The NTP protocol (Network Time Protocol) has since the earliest days of the internet been responsible for synchronising the time across computer networks. Not only is NTP effective at this, but when connected to a source of UTC (Coordinated Universal Time) NTP is also extremely accurate.

Most computer networks connect to UTC via a dedicated NTP time server. These devices use an external connection to an atomic clock to receive the time and then distribute it across a network. By connecting externally, via GPS (Global Positioning System) or long wave radio , not only are NTP time servers incredibly accurate but they are also very secure as they don’t rely on an internet connection for the time.
NTP time servers are also increasingly being used for other new innovations. Not only have traditional technologies such as CCTV, traffic lights, air traffic control and the stock exchange, become reliant on time synchronisation with time servers but an increasing amount of modern technologies are too.

NTP time servers are now common in modern digital signage systems (the use of flat screen TVs for out of home advertising). These networked screens are often synchronised to allow scheduled and orchestrated campaigns.

A synchronized digital signage campaign is one method of making an out of home advertising campaign stand-out. This is increasingly important as more and more digital signage is being implemented making a conventional digital signage campaign difficult to engage and catch the eye.

By synchronising multiple screens together with a NTP time server and running a scheduled and timed campaign. This allows content to be scheduled or timed to maximise its impact.

Small time servers can eben be installed directly into the digital signage of LCD enclosure although as most of these tiem synchnisation devices require a GPS or long wave signal the antenna can be problamtic. A better solution is to network the digtal signage and use a single NTP server as a method fo synchonisation.

NTP may be the oldest protocol on the internet and NTP time servers have been around for nearly two decades but this comparatively antique technology and software has never been so much in demand.

The Atomic Clock Scientific Precision

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Precision is becoming increasingly important in modern technologies and none more so than accuracy in time keeping. From the internet to satellite navigation, precise and accurate synchronicity is vital in the modern age.

In fact many of the technologies that we take for granted in today’s world, would not be possible if it wasn’t for the most accurate machines invented – the atomic clock.

Atomic clocks are just timekeeping devices like other clocks or watches. But what stands them apart is the accuracy they can achieve. As a crude example your standard mechanical clock, such as a town centre clock tower, will drift by as much as a second a day. Electronic clocks such as digital watches or clock radios are more accurate. These types of clock drift a second in about a week.

However, when you compare the precision of an atomic clock in which a second will not be lost or gained in 100,000 years or more the accuracy of these devices is incomparable.

Atomic clocks can achieve this accuracy by the oscillators they use. Nearly all types of clock have an oscillator. In general, an oscillator is just a circuit that regularly ticks.

Mechanical clocks use pendulums and springs to provide a regular oscillation while electronic clocks have a crystal (usually quartz) that when an electric current is run through, provides an accurate rhythm.

Atomic clocks use the oscillation of atoms during different energy states. Often caesium 133 (and sometimes rubidium) is used as its hyperfine transitional oscillation is over 9 billion times a second (9,192,631,770) and this never changes. In fact, the International System of Units (SI) now officially regards a second in time as 9,192,631,770 cycles of radiation from the caesium atom.

Atomic clocks provide the basis for the world’s global timescale – UTC (Coordinated Universal Time). And computer networks all over the world stay in sync by using time signals broadcast by atomic clocks and picked up on NTP time servers (Network Time Server).

Network Time Protocol And Network Time Synchronization

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Synchronization of computer networks is something that many administrators take for granted. Dedicated network time servers can receive a time source and distribute it amongst a network, accurately, securely and precisely.

However, accurate time synchronization is only made possible thanks the time protocol NTP – Network Time Protocol.

NTP was developed when the internet was still in its infancy and Professor David Mills and his team from Delaware University were trying to synchronise the time on a network of a few machines. They developed the very earliest rendition of NTP which has continued to be developed to this very day, nearly thirty years after its first inception.

NTP was not then, and is not now, the only time synchronisation software, there are other applications and protocol that do a similar task but NTP is the most widely used (by far with over 98% of time synchronisation applications using it). It is also packaged with most modern operating systems with a version of NTP (usually SNTP – a simplified version) installed on the latest Windows 7 operating system.

NTP has played an important part in creating the internet we know and love today. Many online applications and tasks would not be possible without accurate time synchronization and NTP.

Online trading, internet auctions, banking and debugging of networks all rely on accurate time synchronisation. Even sending an email requires time synchronisation with email server – otherwise computers would not be able to handle emails coming from unsynchronised machines as they may arrive before they were sent.

NTP is a free software protocol and is available online from NTP.org However, most computer networks that require secure and accurate time mostly use dedicated NTP servers that operate external to the network and firewall obtaining the time from atomic clock signals ensuring millisecond accuracy with the world’s global timescale UTC (Coordinated Universal Time).

Common Issues in Time Synchronisation

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Time synchronization is essential in modern computer networking especially with the amount of time sensitive transactions conducted over the internet these days. Without adequate synchronization computer systems will:

  • Be vulnerable to malicious attacks
  • Susceptible to data loss
  • Unable to conduct time sensitive transactions
  • Difficult to debug

Fortunately ensuring a computer network is accurately synchronized is relatively straight forward. There different methods of synchronizing a network to the global timescale UTC (Coordinated Universal Time) but occasionally some common issues do arise.

My dedicated time server is unable to receive a signal

Dedicated NTP time servers receive the time from either long wave transmissions or GPS networks. If using a GPS NTP server then a GPS antenna needs to be situated on a roof to obtain a clear view of the sky. However, a NTP radio receiver does not need a roof mounted aerial although the signal can be vulnerable to interference and the correct angle toward the transmitter should be attained.

I am using a public time server across the Internet but my devices are not synchronised.

As public time servers can be used by anyone they can receive high levels of traffic. This can cause problems with bandwidth and mean that your time requests can’t get through. Public NTP servers can also fall victim to DDoS attacks and some high profile incidents of NTP vandalism have occurred.

Internet time servers are also stratum 2 devices, in other words they themselves have to connect to a time server to receive the correct time and because of this some online time references are wildly inaccurate.

*NB – internet time servers are also incapable of being authenticated to allow NTP to establish if the time source is coming from where it claims to be, combined with the problem of ensuring the firewall is open to receive the time requests, can mean that internet time servers present a clear risk to security.

The time on my computer seems to be off by a second to standard UTC time

You need to check if a recent leap second has been added to UTC. Leap seconds are added once or twice a year to ensure UTC and the Earth’s rotation match. Some time servers experience difficulties in making the leap second adjustment.

Atomic Clock Synchronization made easy with a NTP Time Server

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Atomic clocks are the ultimate in timekeeping devices. Their accuracy is incredible as an atomic clock will not drift by as much as a second within a million years, and when this is compared to the next best chronometers, such as electronic clock that can drift by a second in a week, an atomic clock is incredibly more precise.

Atomic clocks are used the world over and are the heart of many modern technologies making capable a multitude of applications that we take for granted. Internet trading, satellite navigation, air traffic control and international banking are all industries that rely heavily on

They also govern the world’s timescale, UTC (Coordinated Universal Time) which is kept true by a constellation of these clocks (although UTC has to be adjusted to accommodate the slowing of the Earth’s spin by adding leap seconds).

Computer networks are often required to run synchronized to UTC. This synchronisation is vital in networks that conduct time sensitive transactions or require high levels of security.

A computer network without adequate time synchronization can cause many issues including:

Loss of data

  • Difficulties in identifying and logging errors
  • Increased risk of security breaches.
  • Unable to conduct time sensitive transactions

For these reasons many computer networks have to be synchronized to a source of UTC and kept as accurate as possible. And although atomic clocks are large bulky devices kept in the confines of physics laboratories, using them as a source of time is incredibly simple.

Network Time Protocol (NTP) is a software protocol designed solely for the synchronisation of networks and computer systems and by using a dedicated NTP server the time from an atomic clock can be received by the time server and distributed around the network using NTP.

NTP servers use radio frequencies and more commonly the GPS satellite signals to receive the atomic clock timing signals which is then spread throughout the network with NTP regularly adjusting each device to ensure it is as accurate as possible.

MSF Outages for 2010

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Users of the National Physical Laboratory’s (NPL) MSF time and frequency signal are probably aware that the signal is occasionally taken off-air for scheduled maintenance.

NPL have published there scheduled maintenance for 2010 where the signal will be temporarily taken off-air. Usually the scheduled downtimes lasts for less than four hours but users need to be aware that while NPL and VT Communications, who service the antenna, make every effort to ensure the transmitter is off for a brief amount of time as possible, there can be delays.

And while NPL like to ensure all users of the MSF signal have advanced warning of possible outages, emergency repairs and other issues may lead to unscheduled outages. Any user receiving problems receiving the MSF signal should check the NPL website in case of unscheduled maintenance before contacting your time server vendor.

The dates and times of the scheduled maintenance periods for 2010 are as follows:

* 11 March 2010 from 10:00 UTC to 14:00 UTC

* 10 June 2010 from 10:00 BST to 14:00 BST (UTC + 1 hr)

* 9 September 2010 from 10:00 BST to 14:00 BST (UTC + 1 hr)

* 9 December 2010 from 10:00 UTC to 14:00 UTC

As these scheduled outages should take no longer than four hours, users of MSF referenced time servers should not notice any drop off in accuracy of their network as their shouldn’t be enough time for any device to drift.

However, for those users concerned about accuracy or require a NTP time server (Network Time Server) that doesn’t succumb to regular outages, they may wish to consider investing in a GPS time server.

GPS time servers receive the time from the orbiting navigational satellites. As these are available anywhere on the globe and the signals are never down for outages they can provide a constant accurate time signal (GPS time is not the same as UTC but is easily converted by NTP as it is exactly 17 seconds behind due to leap seconds being added to UTC and not GPS).

How to Synchronise a Computer Network using the Time Protocol (NTP)

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Synchronisation of modern computer networks is vitally important for a multitude of reasons, and thanks to the time protocol NTP (Network Time Protocol) this is relatively straightforward.

NTP is an algorithmic protocol that analyses the time on different computers and compares it to a single time reference and adjusts each clock for drift to ensure synchronisation with the time source. NTP is so capable at this task that a network synchronised using the protocol can realistically obtain millisecond accuracy.

Choosing the time source

When it comes to establishing a time reference there really is no alternative than to find a source of UTC (Coordinated Universal Time). UTC is the global timescale, used throughout the world as a single timescale by computer networks. UTC is kept accurate by a constellation of atomic clocks throughout the world.

Synchronising to UTC

The most basic method of receiving a UTC Time source is to use a stratum 2 internet time server. These are deemed stratum 2 as they distribute the time after first receiving it from a NTP server (stratum 1) that is connected to an atomic clock (stratum 0). Unfortunately this is not the most accurate method of receiving UTC because of the distance the data has to travel from host to the client .

There are also security issues involved in using an internet stratum 2 time source in that the firewall UDP port 123 has to be left open to receive the time code but this firewall opening can, and has been, exploited by malicious users.

Dedicated NTP Servers

Dedicated NTP time servers, often referred to as network time servers, are the most accurate and secure method of synchronising a computer network. They operate externally to the network so there are no firewall issues. These stratum 1 devices receive the UTC time direct from an atomic clock source by either long wave radio transmissions or the GPS network (Global Positioning System). Whilst this does require an antenna, which in the case of GPS has to be placed on a rooftop, the time server itself will automatically synchronise hundreds and indeed thousands of different devices on the network.

Five Reasons why your Network needs a NTP Server

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Accurate timekeeping if quite often overlooked as a priority for network administrators yet many are risking both security and data loss by not ensuring their networks are synchronised as precisely as possible.

Computers do have their own hardware clocks but these are often just simple electronic oscillators such as exist in digital watches and unfortunately these system clocks are prone to drift, often by as much as several seconds in a week.

Running different machines on a network that have different times – even by only a few seconds – can cause havoc as so many computer tasks rely on time. Time, in the form of timestamps, is the only reference computers use to distinguish between different events and failure to accurately synchronize a network can lead to all sorts of untold problems.

Here are some of the major reasons why your network should be synchronised using Network Time Protocol, prefasbly with a NTP time server.

Data Backups – vital to safeguard data in any business or organization, a lack of synchronisation can lead to not only back ups failing but older versions of files replacing more modern versions.

Malicious Attacks – no matter how secure a network, somebody, somewhere will eventually gain access to your network but without accurate synchronisation it may become impossible to discover what compromises have taken place and it will also give any unauthorised users extra time inside a network to wreak havoc.

Error logging – when faults occur, and they inevitably do, the system logs contain all the information to identify and correct problems. However, if the system logs are not synchronised it can sometimes be impossible to figure out what went wrong and when.

Online Trading – Buying and selling on the internet is now commonplace and in some businesses thousands of online transactions are conducted every second from seat reservation to buying of shares and a lack of accurate synchronisation can result in all sorts of errors in online trading such as items being bought or sold more than once.

Compliance and legality – Many industrial regulations systems require an auditable and accurate method of timing. A unsynchronised network will also be vulnerable to legal issues as the exact time an event is alleged to have taken place can not be proved.

Using NTP to Synchronise a Digital Signage System

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Digital signage is advancing quite rapidly for such a burgeoning new industry. Fantastic new innovations and content styles are being developed all the time and there are some really fantastic campaigns out there and more and more adventurous implementations are springing up all the time.

One of a growing number of trends is the use of complicated, scheduled and synchronised campaigns on multiple machines. These are incredibly eye-catching especially when the content is synchronised to provide passers-by with an almost interactive experience.

Synchronised content can be really challenging to implement and this sort of content is certainly not for the beginner as setting up such a sophisticated campaign can be really difficult.

One of the essential aspects of these types of scheduled digital signage campaigns is to ensure all displays are synchronized together. Synchronization is perhaps the most crucial aspect of these types of sophisticated digital signage campaigns. There are multiple methods of synchronising this type of campaign.

One solution is to a network time server which receives a single time source and distributes it amongst all devices on that network using the time protocol NTP (Network Time Protocol).

NTP servers receive the time from an external source (normally GPS or long wave radio) so there is no need to have the network connected to the internet although it is just as possible to synchronise to an internet time source although this can be problematic if there is any disturbance in the internet connection.

Any large network of digital signage displays also need to be protected, especially if media players or PCs are being used to generate content. The best option for ensuring total security is to place both the screen and media device in a display enclosure, often referred to as an LCD enclosure.

Rubidium Oscillators Additional Precision for NTP Serve (Part 2)

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Continued…

However, there are some occasions when a time server can lose connection with the atomic clock and not receive the time code for a prolonged period of time. Sometimes this may be because of downtime by the atomic clock controllers for maintenance or that nearby interference is blocking the transmission.

Obviously the longer the signal is down the more potential drift may occur on the network as the crystal oscillator in the NTP server is the only thing keeping time. For most applications this should never be a problem as the most prolonged period of downtime is not normally more than three or four hours and the NTP server would not have drifted by much in that time and the occurrence of this downtime is quite rare (maybe once or twice a year).

However, for some ultra precise high end applications rubidium crystal oscillators are beginning to be used as they don’t drift as much as quartz. Rubidium (often used in atomic clocks themselves instead of caesium) is far more accurate an oscillator than quartz and provides better accuracy for when there is no signal to a NTP time server allowing the network to maintain a more accurate time.

Rubidium itself is an alkali metal, similar in properties to potassium. It is very slightly radioactive although poses no risk to human health (and is often used in medicine imaging by injecting it into a patient). It has a half life of 49 billion years (the time it takes to decay by half – in comparison some of the most lethal radioactive materials have half-lives of under a second).

The only real danger posed by rubidium is that it reacts rather violently to water and can cause fire