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Atomic Clocks and the GPS Time Server

Atomic clocks have been around since the 1950’s when NPL (National Physical Laboratory) in the UK developed the first reliable caesium based clock. Before atomic clocks, electronic clocks were the most accurate method of keeping track of time but while an electrical clock may lose a second in every week or so, a modern atomic clock will not lose a single second in hundreds of millions of years.

Atomic clocks are not just used to keep track of time. The atomic clock is an integral part of the GPS system (Global Positioning System) as each GPs satellite has its own onboard atomic clock that generates a time signal that is picked up by GPS receivers who can calculate their position by using the precise signal from three or more satellites.

Atomic clocks need to be used as the signal s from the satellites travel at the speed of light and as light travels nearly 300,000 km each second any slight inaccuracy could put navigation out by miles.

A GPS time server is a network time server that uses the time signal from the GPS network’s satellites to synchronise the time on computer networks. A GPS time server often uses NTP (Network Time Protocol) as a method of distributing time which is why these devices are often referred to as NTP GPS time servers.

Computer networks that are synchronised using a dedicated time server are normally synchronised to UTC (Coordinated Universal Time) and while the GPS signal is not UTC, GPS time, like UTC, is based on International Atomic Time (TAI) and is easily converted by NTP.

Step by Step Installing A Dedicated NTP Time Server

A time server is a crucial piece of kit for any network. Time synchronisation is imperative in keeping a network secure and reliable. Time synchronisation, however, need not be the headache many administrators assume it is going to be.

Most of the difficulties of time synchronisation have been taken care of thanks to the protocol NTP (Network Time Protocol). Whilst NTP is not the only time synchronisation software available it is by far the most widely used (due mainly to the fact that it has been around since the 1980’s and is sill being developed today).

NTP uses a single time source and distributes it from machine-to-machine checking each PC or device for drift then adjusting for it. NTP is normally installed on Windows and Linux systems (or at least a simplified version called SNTP) although it is freely downloadable from the NTP homepage. While NTP can quite easily receive any time source from the Internet this can cause major security issues no to mention a lack of accuracy that many online NTP servers suffer from.

The most accurate and secure method is to use an external network time server as these sit within the firewall. They are also receive a UTC (Coordinated Universal Time) reference direct from an atomic clock which makes them stratum 1 devices. Most internet time servers are stratum 2 servers. NTP uses strata to define how far away a server is from the source so an atomic clock is a stratum 0 device while a computer that receives time direct from a NTP server becomes a stratum 2 device and so on.

The only decision that really needs to be made when installing a dedicated NTP time server is which time reference is best. There are two main methods of receiving a secure, accurate and authenticated UTC time reference; the GPS network (Global Positioning System) or national physics laboratories long wave radio transmissions.

The latter system is not available in every country although the USA, UK and Germany have strong signals known as WWVB, MSF and DCF respectively. These can often be picked up outside the borders of these countries although the signals are vulnerable to interference, outages and local topography.

A GPS NTP server system is less vulnerable to these things and as long as there is a clear view of the sky (such as a rooftop or open window) the GPS time signal can be picked up anywhere on the globe.

Useful NTP server related resources

NTP homepage–  The home for the NTP Project who provides support and additional development resources for the Official Reference Implementation of NTP.

NTP Project support pages

THE NTP pool – list of public servers

NPL – The National Physical Laboratory in the UK who control the MSF radio signal.

The University of Delaware and David Mills’ information page, Professor Mills is the original inventor and developer of NTP

David Mills’ list of Public NTP Time Servers a list of public NTP servers

National Institute of Standards and Technology (NIST) who operate the USA’s WWVB radio signal

Europe’s largest supplier of NTP server related products.

Galleon UK – NTP server products for the UK

NTP Time Server .com  – one of the largest time and frequency suppliers in the United States

NTP – Wikipedia article on NTP

NTP server checker – free tool to ensure time server accuracy

The NTP Server and Accurate Time

Accurate time on a network is essential for all businesses and institutions. Without an accurately synchronised system a computer network can be vulnerable to all sorts of problems, from malicious hackers and other security threats to fraud and data loss.
Network Time Protocol is the key to keeping accurate time it is a software algorithm that has been constantly developed for over two decades. NTP takes a single time source that is received by the NTP server and distributes it across a network ensuring all machines in that network are running to exact same time.

Whilst NTP can maintain synchronisation of a network to within a few milliseconds it is only as good as the time source it receives. A dedicated NTP server will use a time signal from an external source and so keep the network secure as the firewall will not have to be disturbed.

The two preferred methods for most users of NTP servers is the GPS network (Global Positioning System) or specialist time and frequency transmissions put out be several national physics labs such as the UK’s NPL.

These time signals are UTC (Coordinated Universal Time) which is the world’s civil timescale. An NTP server receiving time source from either a frequency transmission or the GPS network can realistically provide accuracy to within a few milliseconds of UTC

Network time servers are preferred as a synchronisation tool rather than the much simpler internet time servers because they are far more secure. Using the internet as a basis for time information would mean using a source outside the firewall which could allow malicious users to take advantage.

Network time servers on the other hand work inside the firewall, both of these type of signals are incredibly accurate and secure with each method providing millisecond accuracy to UTC. However, there are downsides to both systems. The radio signals broadcast by nation time and frequency laboratories are susceptible to interference and locality, while the GPS signal, although available literally everywhere on the globe can occasional be lost too (often due to bad weather interfering with the line-of-sight GPS signals.

For computer networks where high levels of accuracy are imperative, dual systems are often incorporated. These dual network time servers receive the time signal from both the GPS network and the radio transmissions and select an average for even more accuracy.  However, the real advantage of using a dual system is that if one signal fails, for what ever the reason, the network will not have to rely on the inaccurate system clocks as the other method of receiving UTC time should still be operational.

Does My Business Need Accurate Time Synchronisation Five question (part 2)

Keeping accurate time on a network with a NTP time server is highly important here is the second part of the article that explains why.

Legal protection – Whether it is a payment dispute with a supplier or customer or even a case of fraud committed against your company only an accurate method of synchronisation will be accepted as a legal defence. An NTP time server is legally auditable and can be used as evidence in a court of law.

Company Credibility:
Being victim to any of these potential hazards can have devastating effects on your own business but also that of your suppliers and customers. Once word gets out too it will soon become common knowledge amongst your competitors, customers and suppliers as news travels quickly in the business world. Keeping credibility is a good enough reason in itself to ensure a computer network is adequately synchronised.

If you have answered yes to any of the above questions then it is time your company invested in a dedicated NTP time server to accurately synchronise you computer network to.  Dedicated time servers use the protocol NTP (Network Time Protocol) as a method of distributing a single time source around the internet. UTC (Coordinated Universal Time) is the preferred time standard that most networks are synchronised to.

An NTP time server can receive a secure and accurate UTC time signal from the GPS network or from long wave radio transmissions broadcast by several national physics laboratories.

Does My Business Need Accurate Time Synchronisation Five question (part 1)

Time synchronisation can be crucial for many computer networks. Correct synchronisation can protect a system from all sorts of security threats it will also ensure that the network is accurate and reliable but are dedicated NTP time server systems really necessary or can a network be run securely without a network time server?

Here are five questions to ask yourself to see if your network needs to be adequately synchronised.

1.  Does your network conduct time sensitive transactions across the internet?

If yes then accurate network time synchronisation is essential. Time is the only point of reference a computer has to identify two events so when it comes to a transaction across the internet such as sending an email, if it comes from an unsynchronised network, it may arrive before it was technically sent. This may lead to the email not being received as a computer cannot handle negative values when it comes to time.

2. Do you store valuable data?

Data loss is another ramification of not having a synchronised network. When a computer stores data it is stamped with the time. If that time is from an unsynchronised machine on a network then a computer may consider the data already saved or it may overwrite new data with older versions.

3. Is security important to your business and network?

Keeping a network secure is essential if you have any sensitive data on the machines. Malicious users have a myriad of ways of gaining access to computer networks and using the chaos caused by an unsynchronised network is one method they frequently take advantage of. Not having a synchronised network may mean it is impossible to identify if your network has been hacked into too as all records left on log files are time reliant too.

NTP Server Time Tired of Inaccurate and Insecure Time

The internet has been a marvellous resource for business over the last decade. High speed access and the proliferation of computers in homes and offices alike have turned the World Wide Web into the main business arena for many companies.

With more and more transactions being conducted from opposite ends of the world across the internet, the need for an accurate and precise clock to keep computer networks synchronised has never been greater.

Most of the world’s computer networks, synchronise to a source of UTC (Coordinated Universal Time) which is the worldwide standard and is controlled by atomic clocks. A worldwide standard for synchronising the clocks has been developed also. NTP (Network Time Protocol) is a software algorithm that distributes UTC amongst a network’s clocks and adjusts the time accordingly.

Many computer network administrators turn to the internet as a source of NTP server time as there are a multitude of sources of UTC time. However, many internet sources of NTP time cannot be relied upon to provide accurate time. Surveys have discovered more than half of all internet time servers were inaccurate by over a second and even those that are not, they could be too far away to provide any useful precision.

More importantly, however, is that internet based NTP servers are external to a network’s firewall so any regular communication with a NTP server will require the firewall port to be left open allowing easy access for malicious users to take advantage of.

The only solution for getting a source of NTP server time, whilst keeping a network secure, is to use an external stratum 1 NTP time server. These devices communicate directly with an atomic clock either via the GPS satellite network or long wave radio signals. Because these devices operate from with the firewall the entire network is kept secure whilst the NTP server distributes an accurate, precise and source of UTC time.

Using Time and Frequency Transmissions to Synchronise a Computer Network

Computer network synchronisation is often perceived as a headache for many system administrators but keeping accurate time is essential for any network to remain secure and reliable. Failing to have an accurate synchronised network can lead to all sorts of errors when dealing with time sensitive transactions.

The protocol NTP (Network Time Protocol) is the industry standard for time synchronisation. NTP distributes a single time source to an entire network ensuring all machines are running the exact same time.

One of the most problematic areas in synchronising a network is in the selection of the time source. Obviously if you are spending time getting a network synchronised then the time source would have to be a UTC (Coordinated Universal Time) as this is the global timescale used by computer networks all over the world.

UTC is available across the internet of course but internet time sources are not only notoriously inaccurate but using the internet as a time source will leave  computer system open to security threats as the source is external to the firewall.

A far better and secure method is to use a dedicated NTP time server. The NTP server sits inside the firewall and can receive a secure time signal from highly accurate sources. The most commonly used these days is the GPS network (Global Positioning System) this is because the GPS system is available literally anywhere on the planet. Unfortunately it does require a clear view of the sky to ensure the GPS NTP server can ‘see’ the satellite.

There is another alternative however, and that is to use the national time and frequency transmissions broadcast by several national physics laboratories. These have the advantage in that being long wave signals they can be received indoors. Although it must be noted these signals are not broadcast in every country and the range is finite and susceptible to interference and geographical features.

Some of the main transmissions broadcast are known as: the UK’s MSF signal, Germany’s DCF-77 and the USA’s WWVB.

Using GPS to Synchronise Network Time

The global positioning system has been around since the 1980’s. It was designed and built by the United States Military who wanted an accurate positioning system for battlefield situations. However, following the accidental shooting down or a Korean airliner, the then US president (Ronald Reagan) agreed that the system should be allowed to be used by civilians as a way of preventing such a disaster from occurring again.

From then on the system has broadcast in to two frequencies L2 for the US Military and L1 for civilian use. The system works by using ultra precise atomic clocks that are on board each satellite. The GPS transmission is a timecode produced from this clock combined with information such as the position and velocity of the satellite. This information is then picked up by the satellite navigation receiver that calculates how long the message took to reach it and therefore how far from the satellite it is.

By using triangulation (use of three of these signals) the exact position on Earth of the GPS receiver can be ascertained. Because the speed of the transmissions, like all radio signals, travels at the speed of light it is highly important that the GPS clocks are ultra-precise. Just one second of inaccuracy is enough to make the navigational unit inaccurate to over 100,000 miles as light can travel such vast distances in such a short space of time.

Because GPS clocks have such a high level of accuracy it means they also have another use. The GPS signal, being available anywhere on the planet, is a highly efficient means of getting a time signal to synchronise a computer network too. A dedicated GPS time server will receive the GPS signal then convert the atomic time signal from it (known as GPS time) and convert it to UTC (Coordinated Universal Time) which is simple to do as both timescales are based on International Atomic Time (TAI) and the only difference being GPS time does not account for leap seconds meaning it is ‘exactly’ 15 seconds faster.

A GPS time server will most likely use the protocol NTP (Network Time Protocol) to distribute the time to a network. NTP is by far the most commonly used network time protocol and is installed in most dedicated time servers and a version is also included in most Windows and Linux operating systems.

UTC and Global Synchronisation

A global economy has many benefits allowing trade and commerce to be conducted relatively pain free from the other sides of the planet. But conducting business with other countries can have its problems most notably time differences.

We are used to the fact that when we go to bed in Europe, those in Australasia are jest getting up and for many businesses, knowing the time in the country that you trade in is essential. However many global transactions are now conducted online and quite often completely automated.

For this reason computers need to know the exact time too, particularly if they are selling products and services that have a limited quantity and any miscalculation in the time can cause untold errors. For instance, if people across the globe wish to buy an airline ticket from an American broker then the computer needs to know who ordered the seat first otherwise there could be a risk of double-booking.

For this reason a global timescale has been developed allowing the whole world to synchronise to one timescale. This global timescale is commonly known as UTC (Coordinated Universal Time) and is based onthe old timescale GMT (Greenwich Meantime) although it accounts for the slowing of the Earth due to tidal and lunar forces.

UTC is kept accurate by atomic clocks that boast an accuracy of a second every 100 million years, however, atomic clocks are highly expensive to own, operate and run and are therefore impractical for a business that just wants to keep accurate UTC.

For this reason the dedicated NTP time server has been developed that can receive a transmitted time signal from an atomic clock and synchronise an entire computer network to it.

The NTP time server can receive a time signal directly from a physic laboratory using a long wave receiver or more conveniently using the GPS signals that are transmitted by satellites 30,000 km above the Earth.

By using a NTP time server a business network can be kept to within a few milliseconds of UTC (thousandth of seconds) ensuring that they can trade and do business with complete and accurate synchronisation.