Archive for the ‘gps time server’ Category

Receiving Time Signals with GPS

Wednesday, August 17th, 2011

Accurate time is one of the most important aspects to keeping a computer network secure and safe. Places such as stock exchanges, banks and air traffic control rely on secure and accurate time. As computers rely on time as their only reference for when events happen, a slight error in a time code could lead to all sorts of errors, from millions being wiped off share prices to aeroplane flight paths being incorrect.

GPS time signals are secure

And time doesn’t just need to be accurate for these organizations, but secure too. A malicious user who interferes with a timestamp could cause all sorts of trouble, so ensuring time sources are both secure and accurate is vital.

Security is increasingly important for all sorts of organisations. With so much trade and communication conducted over the internet, using a source of accurate and secure time is as important a part of network security as anti-virus and firewall protection.

Despite the need for accuracy and security, many computer networks still rely on online time servers. Internet sources of time are not only unreliable, with inaccuracies commonplace, and distance and latency affecting the precision, but an Internet time server is also unsecure and able to be hijacked by malicious users.

But an accurate, reliable and completely secure source of time is available everywhere, 365 days a year—GPS.

While commonly thought of as a means of navigation, GPS actually provides an atomic clock time code, direct from the satellite signals. It is this time code that navigation systems use for calculating position but it is just as effective to provide a secure time stamp for a computer network.

Organizations that rely on accurate time for safety and security all use GPS, as it is a continuous signal, that never goes down, is always accurate and can’t be interfered with by third parties.

To utilise GPS as a source of time, all that is required is a GPS time server. Using an antenna, the time server receives the GPS signal, while NTP (Network Time Protocol) distributes it around the network.

GPS time server

With a GPS time server, a computer network is able to maintain accuracy to within a few milliseconds of the atomic clock time signal, which is translated into UTC time (Coordinated Universal Time) thanks to NTP, ensuring the network is running the same accurate time as other networks also synchronised to a UTC time source.

The Accuracy of the Speaking Clock

Wednesday, December 15th, 2010

The UK speaking clock has been around for nearly eighty years. It was started in 1936 when time keeping started to become more important to people’s lives. Initially available only in the London it was rolled out to the whole country during World War II.

There have been four people that have had honour of providing the permanent voice to the speaking clock over the last 70. And over 70 million calls are made to the speaking clock making it an important from of accurate time but have you ever wondered how accurate it is and where the time comes from and how accurate it is?

The speaking clock is controlled by a major British telecoms company who took over the General Post Office (GPO) and the time was originally supplied by the National Physical Laboratory (NPL) who also provide the MSF signal that NTP time servers use as a source of atomic clock synchronisation.

NPL no longer help with the speaking clock but the time is still controlled by NTP servers, either GPS or MSF, which ensures that the time you hear on the end of the telephone is accurate.

NTP servers are also commonly used by computer networks to ensure that IT systems, from traffic light signals to the office PC are all running an accurate form of time.

NTP time servers can either receive the MSF radio signal broadcast by NPL or, more commonly now, GPS signals beamed directly from space.

Often network administrators opt to use online NTP servers that send time signals over the internet but these are not as accurate and cause security problems so it is far better to have a dedicated NTP time server to control the time if you wish to have a computer network that is running accurately.

Finding an Online NTP Time Source

Wednesday, December 8th, 2010

Finding a source of time to synchronise a computer network to can be a challenge as there are a myriad of online time sources, all pertaining to be accurate and reliable; however, the truth can be rather different with many online sources either in too much demand, too far away or inaccurate.

NTP (Network Time Protocol) requires a source of UTC time (Coordinated Universal Time) which is kept true by atomic clocks. Online time sources are not themselves atomic clocks but NTP server devices that receive the time from an atomic clock which is then relayed to the devices that connect to the online time server.

There are two types of online time server: stratum 1 devices – devices that receive the time directly from an atomic clock, either using GPS or a radio reference signal. Stratum 2 devices  on the other hand are one step further away in that they are receive their time from a stratum 1 time server.

Because of demand, finding an online stratum 1 time server is next to impossible, and those that do take request usually do so under a subscription, which leaves the only choice for most people being a stratum 2 device.

There are plenty of resources on the internet that provide locations for online time servers such as http://support.microsoft.com/kb/262680

But there are drawbacks to using such devices; firstly, online stratum 2 time sources can’t be guaranteed and several surveys taken have found that the reliability and accuracy of many of them can’t be taken for granted.  Secondly, online sources of time require an open firewall port which can be manipulated by malicious bots or users – leading to security risks.

A far better solution for most networks is to install your own stratum 1 NTP server. These time server devices sync to atomic clocks outside the firewall (using GPS or radio signals) and therefore are not security risks. They are also accurate to a few milliseconds ensuring the network will always be accurate to UTC.

Using Atomic Clock Time Signals

Wednesday, November 10th, 2010

Accuracy is becoming more and more relevant as technology becomes increasingly important to the functioning of our everyday lives. And as our economies become more reliant on the global marketplace, accuracy and synchronisation of time is very important.

Computers seem to control much our daily lives and time is essential for the modern computer network infrastructure. Timestamps ensure actions are carried out by computers and are the only point of reference IT systems have for error checking, debugging and logging. A problem with the time on a computer network and it could lead to data getting lost, transactions failing and security issues.

Synchronisation on a network and synchronisation with another network that you communicate with are essential to prevent the above mentioned errors. But when it comes to communicating with networks across the globe things can be even trickier as the time on the other-side of the world is obviously different as you pass each time-zone.

To counter this, a global timescale based on atomic clock time was devised. UTC – Coordinated Universal Time – does away with time-zones enabling all networks across the globe to use the same time source – ensuring that computers, no matter where they are in the world, are synchronised together.

To synchronise a computer network, UTC is distributed using the time synchronisation software NTP (Network Time Protocol). The only complication is receiving a source of UTC time as it is generated by atomic clocks which are multi-million dollar systems that are not available for mass use.

Fortunately, signals from atomic clocks can be received using a NTP time server. These devices can receive radio transmissions that are broadcast from physic laboratories which can be used as a source of time to synchronise an entire network of computers to.

Other NTP time servers use the signals beamed from GPS satellites as a source of time. The positioning information in these signals is actually a time signal generated by atomic clocks onboard the satellites (which is then triangulated by the GPS receivers).

Whether it’s a radio referenced NTP server or a GPS time server – an entire network of hundreds, and even thousands of machines can be synchronised together.

The Effects of No Time Signal

Wednesday, November 3rd, 2010

NTP servers (Network Time Protocol) are an essential tool in the modern computer network. They control the time, ensuring every device on the network is synchronised.

Because of the importance of time in controlling nearly every aspect of computer networking accurate and synchronised time is essential which is why so many system administrators deploy a NTP time server.

These time servers use a single time source as a base to set all the clocks on a network to; the time is often got from the GPS network or radio signals broadcast from physics laboratories such as NPL in the UK (whose signal is broadcast from Cumbria).

Once this signal is received by the time server, the time protocol NTP then distributes it around the network – comparing the system clock of every device to the time reference and adjusting each device. By regularly assessing the drift of these devices and correcting for them NTP keeps clocks accurate to within milliseconds of the time signal and when this signal emanates from an atomic clock – it ensures the network is as accurate as physically possible, but what happens if you lose the time signal?

Damaged GPS antennas, maintenance of time signal transmitters or technical faults can lead to a NTP time sever failing to receive a time signal. Often, this is only temporary and normal service is resumed within a few hours but what happens if it doesn’t, and what is the effect of having a failed time signal?

Fortunately, NTP has back-up systems for just such an eventuality. If a time signal fails and there is no other source of time, NTP cleverly uses the average time from all the clocks on its network. So if some clocks have drifted a few milliseconds faster, and others a few milliseconds slower – then NTP takes the average of this drift ensuring that the time remains accurate for as long as possible.

Even if a signal has failed for several days – or even weeks – without knowledge of the system users, this does not mean the network will drift apart. NTP will still keep the entire network synchronised together, using the average drift, and while the longer the time signal remains off the les accurate the network will be it can still provide millisecond accuracy even after a few days of no time reference.

Time Synchronisation Getting it Right

Wednesday, October 20th, 2010

Time is essential for computers, networks and technology. It is the only reference technology has to ascertain if a task has happened or is due to take place. As time, in the from of timestamps, is so important for technology, when there is uncertainty over time, due to different devices on a network having different times, it can cause untold errors.

The problem with time in computing is that all devices, from routers to desktop PCs, have their own onboard timepiece that governs the system clocks. These system clocks are just normal electronic oscillators, they type commonly found in battery powered watches, and while these are adequate for humans to tell the time, the drifting of these clocks can see devices on a network, seconds and even minutes out of sync.

There are two rules for time synchronisation:

  • All devices on a network should be synchronised together
  • The network should be synchronised to UTC (Coordinated Universal Time)

 

NTP

To synchronise a network you need to make use of Network Time Protocol (NTP). NTP is designed for accurate network time synchronisation.  IT works by using a single source of time which it then distributes it to all devices on the NTP network.

NTP continually checks the devices for any drift and then adjusts to ensure the entire network is within a few milliseconds of the reference time.

UTC

Coordinated Universal Time is a global timescale that is kept true by atomic clocks. By synchronising a network to UTC you are in effect ensuring your network is synchronised to every other UTC network on the planet.

Using UTC as a reference source is a simple affair too. NTP time servers are the best way to find a secure source of UTC time. They use either GPS (Global Positioning System) as a source of this atomic clock time or specialist radio signals keeping the UTC time source external to the network for security reasons.

A single NTP server can synchronise a network of hundreds and even thousands of devices ensuring the entire network is to within a few milliseconds of UTC.

Using Atomic Clocks for Time Synchronisation

Wednesday, October 6th, 2010

The atomic clock is unrivalled in its chronological accuracy. No other method of maintaining time comes close to the precision of an atomic clock. These ultra-precise devices can keep time for thousands of years without losing a second in drift – in comparison to electronic clocks, perhaps the next most accurate devices, which can drift up to a second a day.

Atomic clocks are not practical devices to have around though. They use advanced technologies such as super-coolant liquids, lasers and vacuums – they also require a team of skilled technicians to keep the clocks running.

Atomic clocks are deployed in some technologies. The Global Positioning System (GPS) relies on atomic clocks that operate onboard the unmanned orbiting satellites. These are crucial for working out accurate distances. Because of the speed of light that the signals travel, a one second inaccuracy in any GPS atomic clock would lead to positing information being out by thousands of kilometres – but the actual accuracy of GPS is within a few metres.

While these wholly accurate and precise instruments for measuring time are unparalleled and the expensive of running such devices is unobtainable to most people, synchronising your technology to an atomic clock, in actual fact, is relatively simple.

The atomic clocks onboard the GPS satellites are easily utilised to synchronise many technologies to. The signals that are used to provide positioning information can also be used as a source of atomic clock time.

The simplest way to receive these signals is to use a GPS NTP server (Network Time Protocol). These NTP servers use the atomic clock time signal from the GPS satellites as a reference time, the protocol NTP is then used to distribute this time around a network, checking each device with the GPS time and adjusting to ensure accuracy.

Entire computer networks can be synchronised to the GPS atomic clock time by using just one NTP GPS server, ensuring that all devices are within milliseconds of the same time.

NTP and GPS-based Timing Solutions

Wednesday, September 22nd, 2010

Ask anybody what the key to network timing is and you will probably get the response NTP (Network Time Protocol).  NTP is a protocol that distributes and checks the time on all network devices to a reference clock – and it is this reference which is the true key to network time synchronisation.

Whilst a version of NTP is easy to obtain – it is normally installed on most operating systems, or is otherwise free to download – but getting a source of time is where the true key to network time synchronisation lies.

Atomic clocks govern the global timescale UTC (Coordinated Universal Time) and it is this timescale that is best for network timing as synchronising all devices on a network to UTC is equivalent of having you network synchronised with every other UTC synced network on Earth.

So getting a source of UTC time is the true key to accurate network time synchronisation, so what are the options?

Internet Time Sources

The obvious choice for most NTP users, but internet time suffers from two major flaws; firstly, internet time operates through the firewall and is therefore fraught with security risks – if the time can get through your firewall, then other things can too. Secondly, internet time sources can be hit and miss with their accuracy.

Due to the fact most internet time sources are stratum 2 devices (they connect to another device that receives the UTC source time) and the distance from client to host can never be truly ascertained or accounted for – it can make them inaccurate – with some internet time sources minutes, hours and even days away from true UTC time.

Radio Referenced Time Server

Another source of UTC time which doesn’t suffer from either security or accuracy flaws is receiving the time from long wave radio signals that some country’s national physics laboratories broadcast. While these signals are available throughout the USA (courtesy of NIST) the UK (NPL) and several other European countries and can be picked up witha basic radio referenced NTP server they are not available everywhere and the signals can be difficult to receive in some urban locations or anywhere where there is electrical interference.

GPS-timing

For completely accurate, secure and a reliable source of UTC time there is no substitute for GPS time. GPS timing signals are beamed directly from atomic clocks onboard the GPS satellites (Global Positioning System) and received by GPS NTP time servers. These can then distribute the atomic clock time around the network.

GPS timing sources are accurate, secure and available literally anywhere on the planet 24 hours a day.

An End to British Summer Time?

Wednesday, August 18th, 2010

The new UK government is to look again at the perennial debate about changing the clocks during the summer months from GMT (Greenwich Mean Time) to British Summer Time (BST).

While the move is controversial, with many in Scotland in the north of the UK, unwilling to adopt the change due to the longer dark days of winter they experience over the rest of the country – the move would help synchronise Britain with the rest of Europe.

Despite its positing in the European Union, Britain holds a different timescale to the rest of Europe. People from the UK who travel abroad have to advance their watches an hour every-time they travel to mainland Europe.

In the new proposals, daylight saving time will still continue but the standard winter time will be advanced an hour and a further advancement of an hour for the summer – know as double British Summertime – allowing the UK to have the same time as Europe.

However, despite the problems such a change would have to people; technology will not be affected by any alteration in daylight saving time.

UTC Time

Technology, such as computer networks, all use a universal time – UTC (Coordinated Universal Time). UTC is a global timescale, kept true by an international conglomeration of atomic clocks. This means whether you have a UK based computer network, or a one on the other side of the world, to the technologies – the time is the same.

Most technologies receive this time from an atomic clock source using devices known as NTP servers (after the time protocol: Network Time Protocol). NTP servers take advantage of the atomic clocks onboard GPS satellites so they can not only supply an accurate source of time but they can assure that the time source never drifts.

Other methods of getting an atomic clock source of time include using medium wave transmissions broadcast by places like the UK’s National Physical Laboratory (NPL) or the American National Institute for Standards and Time.

NTP servers ensure that no matter where you are in the world the source of time your computers and technology utilise is always Coordinated Universal Time – no matter what the time of year.



GPS Time Servers Precise Time all the Time

Wednesday, August 11th, 2010

Keeping computer networks accurate and synchronised can’t be emphasised highly enough. Accurate time is essential in the modern global economy as computer networks across the globe are required to constantly talk to each other.

Failing to ensure a network is accurate and precise can lead to headache after headache: transactions can fail, data can get lost, and error logging and debugging can be virtually impossible.

Atomic Clocks

Atomic clocks form the basis of the global timescale – UTC (Coordinated Universal Time). UTC is used across the globe by technology and computer networks enabling the entire commercial and technological world to communicate in synchronicity together.

But as atomic clocks are highly technical (and expensive) pieces of hardware that require a team of technicians to control – where do people get a source of such accurate time?

The answer is quite simple; atomic clock timestamps are transmitted by physics laboratories and are avlaible from a whole host of sources – kept accurate by the time software NTP (Network Time Protocol).

NTP Time Servers

The most common location for sources of atomic clock generated UTC is the internet. A whole host of online time servers are avlaible for synchronisation but these can vary in their accuracy and precision. Furthermore, using a source of internet time can create vulnerabilities in the network as the firewall has to allow these timestamps through and therefore can be utilised by viruses and malicious software.

By far the most secure and accurate method of receiving a source of atomic clock generated time is to utilise the GPS network (Global Positioning System).

GPS time servers are unique in that as long as there is a clear view of the sky they can receive a source of time – anywhere on the globe, 24 hours-a-day, 365 days a year.

They are also highly accurate with a single GPS NTP time server able to synchronise entire networks to just a few milliseconds of UTC.