Importance of the GPS Antenna

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The global positing system is one of the most used technologies in the modern world. So many people rely on the network for either satellite navigation or time synchronisation. The majority of road users now rely on some form of GPS or mobile phone navigation, and professional drivers are almost completely reliant on them.

And its not just navigation that GPS is useful for. Because GPS satellites contain atomic clocks—it is the time signals these clocks put out that are used by satellite navigation systems to accurately work out positioning—they are used as a primary source of time for a whole host of time sensitive technologies.

Traffic lights, CCTV networks, ATM machines and modern computer networks all need accurate sources of time to avoid drift and to ensure synchronicity.  Most modern technologies, such as computers, do contain internal time pieces but these are only simple quartz oscillators (similar type of clock as used in modern watches) and they can drift. Not only does this lead to the time slowly becoming inaccurate, when devices are hooked up together this drifting can leave machines unable to cooperate as each device may have  a different time.

This is where the GPS network comes in, as unlike other forms of accurate time sources, GPS is available anywhere on the planet, is secure (for a computer network it is received externally to the firewall) and incredibly accurate, but GPS does have one distinct disadvantage.

While available everywhere on the planet, the GPS signal is pretty weak and to obtain a signal, whether for time synchronisation or for navigation, a clear view of the sky is needed. For this reason, the GPS antenna is fundamental in ensuring you get a good quality signal.

As the GPS antenna has to go outdoors, it’s important that it s not only waterproof, able to operate in the rain and other weather elements, but also resistant to the variation in temperatures experienced throughout the year.

One of the leading causes of GPS NTP server failure (the time servers that receive GPS time signals and distribute them around a network using Network Time Protocol) is a failed or failing antenna, so ensuring you GPS antenna is waterproof, and resistant to seasonal temperature changes can eliminate the risk of future time signal failures.

Waterproof GPS Antenna

Most Accurate Atomic Clock Yet

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A new atomic clock as accurate as any produced has been developed by the University of Tokyo which is so accurate it can measure differences in Earth’s gravitational field—reports the journal Nature Photonics.

While atomic clocks are highly accurate, and are used to define the international timescale UTC (Coordinated Universal Time), which many computer networks rely on to synchronise their NTP servers to, they are finite in their accuracy.

Atomic clock use the oscillations of atoms emitted during the change between two energy states, but currently they are limited by the Dick effect, where noise and interference generated by the lasers used to read the frequency of the clock, gradually affect the time.

The new optical lattice clocks, developed by Professor Hidetoshi Katori and his team at the University of Tokyo, get around this problem by trapping the oscillating atoms in an optical lattice produced by a laser field. This makes the clock extremely stable, and incredibly accurate.

Indeed the clock is so accurate Professor Katori and his team suggest that not only could it man future GPS systems become accurate to within a couple of inches, but can also measure the difference in the gravitation of the Earth.

As discovered by Einstein in his Special and General Theories of Relativity, time is affected by the strength of gravitational fields. The stronger the gravity of a body, the more time and space is bent, slowing down time.

Professor Katori and his team suggest that this means their clocks could be used to find oil deposits below the Earth, as oil is a lower density, and therefore has a weaker gravity than rock.

Despite the Dick Effect, traditional atomic clocks currently used to govern UTC and to synchronise computer networks via NTP time servers, are still highly accurate and will not drift by a second in over 100,000 years, still accurate enough for the majority of precise time requirements.

However, a century ago the most accurate clock available was an electronic quartz clock that would drift by a second a day, but as technology developed more and more accurate time pieces were required, so in the future, it is highly possible that these new generation of atomic clocks will be the norm.

The Truth about Time

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As a manufacturer of NTP time servers, synchronizing computer networks and keeping them accurate to within a few milliseconds of international UTC time (Coordinated Universal Time), we often think we can keep pretty good track of time.

Time, however, is quit elusive and is not the fixed entity we often assume it is, indeed time, and the time told on Earth is not constant and is affected by all sorts of things.

Since Einstein’s famous equation, E=MC2 it has been acknowledged that time is not constant, and that the only constant in the universe is the maximum velocity of light. Time, as Einstein discovered, is affected by gravity, making the time on Earth run slightly slower than time in deep space, likewise, on planetary bodies with a larger mass than Earth, time runs even slower.

Time slows down when you approach very fast speeds too. The property of time, known as time dilation, was discovered by Einstein and means that at close to the speed of light, time almost stands still (and makes interstellar travel a possibility for science fiction writers).

Generally, living on Earth, these differences in time are not felt, and indeed the slowing of time caused by Earth’s gravity is so minute, highly precise atomic clocks are required to measure it.

However, the time we use to govern our lives is also affected by other factors. Since humans first evolved, we have been used to a day lasting just over 24 hours.  However, the length of a day on Earth is not fixed, and has been changing for the last few billion years.

Each day on Earth differs from the previous to the next one. Often these differences are minute, but year on year, the changes add up as the affect of the moon’s gravity and tidal forces act as a brake on the Earth’s spin.

To cope with this, the global timescale UTC (Coordinated Universal Time) has to be adjusted to prevent the day from drifting out of sync (and we end up with noon at night and midnight during the day—although at the current slowing of the Earth, this would take many thousands of years).

The adjustment in our time is known as leap seconds which are added either once or twice a year to UTC. Anybody using a NTP time server (Network Time Protocol) to synchronise their computer network too, needn’t worry, however, as NTP servers will automatically account for these changes.

Our Time and Travel Reliance on GPS

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Since the Global Positioning System (GPS) first became available for civilian use in the early 1990’s, it has become one of the most commonly used modern pieces of technology. Millions of motorists use satellite navigation, while shipping and airline industries are heavily dependent on it.

And its not just wayfinding that we use GPS for, many technologies from computer network to traffic lights, to CCTV cameras, use the GPS satellite transmissions as a method of controlling time—using the onboard atomic clocks to synchronise these technologies together.

While plenty of advantages to using GPS for both navigation and time synchronisation exist, it’s accurate in both time and positioning and is available, literally everywhere on the planet with a clear view to the sky. However, a recent report by the Royal Academy of Engineering this month has warned that the UK is becoming dangerously dependent on the USA run GPS system.

The report suggests that with so much of our technology now reliant on GPS such as road, rail and shipping equipment, there is a possibility that any loss in GPS signal could lead to loss of life.

And GPS is vulnerable to failure. Not only can GPS satellites be knocked out by solar flares and other cosmological phenomenon, but GPS signals can be blocked by accidental interference or even deliberate jamming.

If the GPS system does fail then navigation systems could become inaccurate leading to accidents, however, for technologies that use GPS as a timing signal, and these range from important systems at air traffic control, to the average business computer network, then fortunately, things should not be that disastrous.

This is because GPS time servers that receive the satellite’s signal use NTP (Network Time Protocol). NTP is the protocol that distributes the GPS time signal around a network, adjusting the system clocks on all the devices on the network to ensure they are synchronised. However, if the signal is lost, then NTP can still remain accurate, calculating the best average of the system clocks. Consequently if the GPS signal does go down, computers can still remain accurate to within a second for several days.

For critical systems, however, where extremely precise time is required constantly, dual NTP time servers are commonly used. Dual time servers not only receive a signal from GPS, but also can pick-up the time standard radio transmissions broadcast by organisations such as NPL or NIST.

A Galleon Systems NTP GPS Time Server

The Fragility of Time Japanese Earthquake Shortens the Day

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The recent and tragic earthquake that has left so much devastation in Japan has also highlighted an interesting aspect about the measurement of time and the rotation of the Earth.

So powerful was the 9.0 magnitude earthquake, it actually shifted Earth axis by 165mm (6½ inches) according to NASA.

The quake, one of the most powerful felt on Erath over the last millennia, altered the distribution of the planet’s mass, causing the Earth to rotate on its axis that little bit faster and therefore, shortening the length of every day that will follow.

Fortunately, this change is so minute it is not noticeable in our day to day activities as the Earth slowed by less than a couple of microseconds (just over a millionth of a second), and it isn’t unusual for natural events to slow down the speed of the Earth’s rotation.

In fact, since the development of the atomic clock in the 1950’s, it has been realised the Earth’s rotation is never continual and in fact has been increasing very slightly, most probably for billions of years.

These changes in the Earth’s rotation, and the length of a day, are caused by the effects of the moving oceans, wind and the gravitational pull of the moon. Indeed, it has been estimated that before humans arrived on Earth, the length of a day during the Jurassic period (40-100 million years ago) the length of a day was only 22.5 hours.

These natural changes to the Earth’s rotation and the length of a day, are only noticeable to us thanks to the precise nature of atomic clocks which have to account for these changes to ensure that the global timescale UTC (Coordinated Universal Time) doesn’t drift away from mean solar time (in other words noon needs to remain when the sun is highest during the day).

To achieve this, extra seconds are occasionally added onto UTC. These extra seconds are known as leap seconds and over thirty have been added to UTC since the 1970’s.

Many modern computer networks and technologies rely on UTC to keep devices synchronised, usually by receiving a time signal via a dedicated NTP time server (Network Time Protocol).

NTP time servers are designed to accommodate these leap seconds, enabling computer systems and technologies to remain accurate, precise and synchronised.

Keeping the World Ticking Over The Global Timekeepers

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When we want to know the time it is very simple to look at a clock, watch or one of the myriad devices that display the time such as our mobile phones or computers. But when it comes to setting the time, we rely on the internet, speaking clock or somebody else watch; however, how do we know these clocks are right, and who is it that ensures that time is accurate at all?

Traditionally we have based time on Earth in relation to the rotation of the planet—24 hours in a day, and each hour split into minutes and seconds. But, when atomic clocks were developed in the 1950’s it soon became apparent that the Earth was not a reliable chronometer and that the length of a day varies.

In the modern world, with global communications and technologies such as GPS and the internet, accurate time is highly important so ensuring that there is a timescale that is kept truly accurate is important, but who is it that controls global time, and how accurate is it, really?

Global time is known as UTC—coordinated Universal Time. It is based on the time told by atomic clocks but makes allowances for the inaccuracy of the Earth’s spin by having occasional leap seconds added to UTC to ensure we don’t get into a position where time drifts and ends up having no relation to the daylight or night time (so midnight is always at day and noon is in the day).

UTC is governed by a constellation of scientists and atomic clocks all across the globe. This is done for political reasons so no one country has complete control over the global timescale. In the USA, the National Institute for Standards and Time (NIST), helps govern UTC and broadcast a UTC time signal from Fort Collins in Colorado.

While in the UK, the National Physical Laboratory (NPL) does the same thing and transmits their UTC signal from Cumbria, England. Other physics labs across the world have similar signals and it is these laboratories that ensure UTC is always accurate.

For modern technologies and computer networks, these UTC transmissions enable computer systems across the globe to be synchronised together. The software NTP (Network Time Protocol) is used to distribute these time signals to each machine, ensuring perfect synchronicity, while NTP time servers can receive the radio signals broadcast by the physics laboratories.

Importance of Atomic Clock Time Sources for Technology

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Timekeeping and accuracy is important in the running of our day-to-day lives. We need to know what time events are occurring to ensure we don’t miss them, we also need to have a source of accurate time to prevent us from being late; and computers and other technology are just as reliant on the tine as we are.

For many computers and technical systems, the time in the form of a timestamp is the only tangible thing a machine has to identify when events should occur, and in what order. Without a timestamp a computer is unable to perform any task—even saving data is impossible without the machine knowing what time it is.

Because of this reliance on time, all computer systems have in-built clocks on their circuit boards. Commonly these are quartz based oscillators, similar to the electronic clocks used in digital wrist watches.

The problem with these system clocks is that they are not very accurate. Sure, for telling the time for human purposes they are precise enough; however, machines quite often require a higher level of accuracy, especially when devices are synchronised.

For computer networks, synchronisation is crucial as different machines telling different times could lead to errors and failure of the network to perform even simple tasks. The difficult with network synchronisation is that the system clocks used by computers to keep time can drift. And when different clocks drift by differing amounts, a network can soon fall into disarray as different machines keep different times.

For this reason, these system clocks are not relied on to provide synchronisation. Instead, a far more accurate type of clock is used: the atomic clock.

Atomic clocks don’t drift (at least not by more than a second in a million years) and so are ideal to synchronise computer networks too. Most computers use the software protocol NTP (Network Time Protocol) which uses a single atomic clock time source, either from across the internet, or more securely, externally via GPS or radio signals, in which it synchronises every machine on a network to.

Because NTP ensures each device is kept accurate to this source time and ignores the unreliable system clocks, the entire network can be kept synchronised to with each machine within fractions of a second of each other.

How GPS Keeps Clocks Accurate

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While many of us are aware of GPS (Global Positioning System) as a navigational tool and many of us have ‘sat navs’ in our cars, but the GPS network has another use that is also important to our day-to-day lives but few people realise it.

GPS satellites contain atomic clocks which transmit to earth an accurate time signal; it is this broadcast that satellite navigation devices use to calculate global position. However, there are other uses for this time signal besides navigation.

Nearly all computer networks are kept accurate to an atomic clock. This is because miniscule accuracies across a network can lead to until problems, from security issues to data loss. Most networks use a form of NTP (Network Time Protocol) to synchronise their networks, but NTP requires a main time source to sync to.

GPS is ideal for this, not only is it an atomic clocks source, which NTP can calculate UTC (Coordinated Universal Time) from, which means that the network will be synchronised to every other UTC network on the globe.

GPS is an ideal source of time as it is available literally everywhere on the planet as long as the GPS antenna has a clear view of the sky. And it is not only computer networks that require atomic clock time, all sorts of technologies require accurate synchronisation: traffic lights, CCTV cameras, air traffic control, internet servers, indeed many modern applications and technology without us realising is being kept true by GPS time.

Top use GPS as a source of time, a GPS NTP server is required. These connect to routers, switches or other technology and receive a regular time signal from the GPS satellites. The NTP server then distributes this time across the network, with the protocol NTP continually checking each device to ensure it is not drifting.

GPS NTP servers are not only accurate they are also highly secure. Some network administrators use internet time servers as a source of time but this can lead to problems. Not only is the accuracy of many of these sources questionable, but the signals can be hijacked by malicious software which can breach the network firewall and cause mayhem.

Keeping a Windows 7 Network Secure, Reliable and Accurate

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Many modern computer networks are now running Microsoft’s latest operating system Window 7, which has many new and improved features including the ability to synchronise time.

When a Windows 7 machine is booted up, unlike previous incarnations of Windows, the operating system automatically attempts to synchronise to a time server across the internet to ensure the network is running accurate time. However, while this facility is often useful for residential users, for business networks it can cause many problems.

Firstly, to allow this synchronisation process to happen, the company firewall must have an open port (UDP 123) to allow the regular time transference. This can cause security issues as malicious users and bots can take advantage of the open port to penetrate into the company network.

Secondly, while the internet time servers are often quite accurate, this can often depend on your distance from the host, and any latency caused by network or internet connection can further cause inaccuracies meaning that you system can often be more than several seconds away from the preferred UTC time (Coordinated Universal Time).

Finally, as internet time sources are stratum 2 devices, that is they are servers that do not receive a first-hand time code, but instead receive a second hand source of time from a stratum 1 device (dedicated NTP time server – Network Time Protocol) which also can lead to inaccuracy – these stratum 2 connections can also be very busy preventing your network from accessing the time for prolonged periods risking drifting.

To ensure accurate, reliable and secure time for a Windows 7 network, there is really no substitute than to use your own stratum 1 NTP time server. These are readily available from many sources and are not very expensive but the peace of mind they provide is invaluable.

Stratum 1 NTP time servers receive a secure time signal direct from an atomic clock source. The time signal is external to the network so there is no danger of it being hijacked or any need to have open ports in the firewall.

Furthermore, as the time signals come from a direct atomic clock source they are very accurate and don’t suffer any latency problems. The signals used can be either through GPS (Global Positioning System satellites’ have onboard atomic clocks) or from radio transmissions broadcast by national physics laboratories such as NIST in the USA (broadcast from Colorado), NPL in the UK (transmitted form Cumbria) or their German equivalent (from Frankfurt).

How the Moon Affects Time on Earth

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We take it for granted that a day is twenty-four hours. Indeed, our body’s circadian rhythm is finally tuned to cope with a 24-hour-day. However, a day on Earth was not always 24 hours long.

In the early days of the Earth, a day was incredibly short – just five hours long, but by the time of the Jurassic period,  when dinosaurs roamed the Earth, a day had lengthened to about 22.5 hours.

Of course now, a day is 24-hours and has been since humans evolved, but what has caused this gradual lengthening. The answer lies with the Moon.

The moon used to be a lot closer to the Earth and the effect of its gravity was therefore, a lot stronger. As the moon drives tidal systems, these were a lot stronger in the early days of the Earth, and the consequence was that the Earth’s spin slowed, the tugging of the moon’s gravity and tidal forces on the Earth, acing like a brake on the rotation of the planet.

Now the moon is farther away, and is continuing to move away even farther, however the effect of the moon is still felt on Earth, with a consequence that Earth’s day is still slowing down, albeit minutely.

With modern atomic clocks, it is now possible to account for this slowing and the global timescale used by most technologies to ensure time synchronisation, UTC (Coordinated Universal Time), has to account for this gradual slowing, otherwise, because of the extreme accuracy of atomic clocks, eventually day would slip into night as the Earth slowed and we didn’t adjust our clocks.

Because of this, once or twice a year, an extra second is added to the global timescale. These leap-seconds, as they are known, have been added since the 1970’s when UTC was first developed.

For many modern technologies where millisecond accuracy is required, this can cause problems. Fortunately, with NTP time servers (Network Time Protocol) these leap seconds are accounted for automatically, so any technologies hooked up to an NTP server need not worry about this discrepancy.

NTP servers are used by time sensitive technology and computer networks worldwide to ensure precise and accurate time, all the time, regardless of what the heavenly bodies are doing.