London 2012 will be the 30th modern Olympic Games, and in its 116-year history, UY98UZDDVGGJ the Olympics have gone through many changes. New events have been introduced, records have been broken and different cities have played host to the games, but one constant has remained – the need to time competitors accurately during the different events. (more…)
Archive for the ‘chronology’ Category
At the end of June this year, several high profiles websites suffered disruption and went down due the inclusion of an additional second to the international time system. The websites, including the social news and networking sites Reddit, Foursquare and Linkedin, were disrupted for several hours thanks to the inclusion of a Leap Second to Coordinated Universal Time (UTC), the world’s global timescale. (more…)
Time synchronisation is something easily taken for granted in this day and age. With GPS NTP servers, satellites beam down time to technologies, which keeps them synced to the world’s time standard UTC (Coordinated Universal Time).
Before UTC, before atomic clocks, before GPS, keeping time synchronised was not so easy. Throughout history, humans have always kept track of time, but accuracy was never that important. A few minutes or an hour or so difference, made little difference to people’s lives throughout the medieval and regency periods; however, come the industrial revolution and the development of railways, factories and international commerce, accurate timekeeping became crucial.
Greenwich Mean Time (GMT) became time standard in 1880, taking over from the world’s first time standard railway time, developed to ensure accuracy with railway timetables. Soon, all businesses, shops and offices wanted to keep their clocks accurate to GMT, but in an age before electrical clocks and telephones, this proved difficult.
Enter the Greenwich Time Lady. Ruth Belville was a businesswoman from Greenwich, who followed in her father’s footsteps in delivering time to businesses throughout London. The Belville’s owned a highly accurate and expensive pocket watch, a John Arnold chronometer originally made for the Duke of Sussex.
Every week, Ruth, and her father before her, would take the train to Greenwich where they would synchronise the pocket watch to Greenwich Mean Time. The Belvilles would then travel around London, charging businesses to adjust their clocks their chronometer, a business enterprise that lasted from 1836 to 1940 when Ruth finally retired at the age of 86.
BY this time, electronic clocks had began to take over traditional mechanical devices and were more accurate, needing less synchronisation, and with the telephone speaking clock introduced by the General Post Office (GPO) in 1936, timekeeping services like the Belville’s became obsolete.
Today, time synchronisation is far more accurate. Network time servers, often using the computer protocol NTP (Network Time Protocol), keep computer networks and modern technologies true. NTP time servers receive an accurate atomic clock time signal, often by GPS, and distribute the time around the network. Thanks to atomic clocks, NTP time servers and the universal timescale UTC, modern computers can keep time to within a few milliseconds of each other.
International Telecommunications Union (ITU), based in Geneva, is voting in January to finally get rid of the leap second, effectively scrapping Greenwich Meantime.
UTC (Coordinated Universal Time) has been around since the 1970’s, and already effectively governs the world’s technologies by keeping computer networks synchronised by way of NTP time servers (Network Time Protocol), but it does have one flaw: UTC is too accurate, that is to say, UTC is governed by atomic clocks, not by the rotation of the Earth. While atomic clocks relay an accurate, unchanging form of chronology, the Earth’s rotation varies slightly from day-to-day, and in essence is slowing down by a second or two a year.
To prevent noon, when the sun is highest in the sky, from slowly getting later and later, Leap Seconds are added to UTC as a chronological fudge, ensuring that UTC matches GMT (governed by when the sun is directly above by the Greenwich Meridian Line, making it 12 noon).
The use of leap seconds is a subject of continuous debate. The ITU argue that with the development of satellite navigation systems, the internet, mobile phones and computer networks all reliant on a single, accurate form of time, a system of timekeeping needs to be precise as possible, and that leap seconds causes problems for modern technologies.
This against changing the Leap Second and in effect retaining GMT, suggest that without it, day would slowly creep into night, albeit in many thousands of years; however, the ITU suggest that large-scale changes could be made, perhaps every century or so.
If leap seconds are abandoned, it will effectively end Greenwich Meantime’s guardianship of the world’s time that has lasted over a century. Its function of signalling noon when the sun is above the meridian line started 127 years ago, when railways and telegraphs made a requirement for a standardised timescale.
If leap seconds are abolished, few of us will notice much difference, but it may make life easier for computer networks that synchronised by NTP time servers as Leap Second delivery can cause minor errors in very complicated systems. Google, for instance, recently revealed it had written a program to specifically deal with leap seconds in its data centres, effectively smearing the leap second throughout a day.
Most of us think we know what the time it is. At a glance of our wristwatches or wall clocks, we can tell what time it is. We also think we have a pretty good idea of the speed time move forwards, a second, a minute, an hour or a day are pretty well-defined; however, these units of time are completely man-made and are not as constant as we may think.
Time is an abstract concept, while we may think it is the same for everybody, time is affected by its interaction with the universe. Gravity, for instance, as Einstein observed, has the ability to warp space-time altering the speed in which time passes, and while we all live on the same planet, under the same gravitational forces, there are subtle differences in the speed in which time passes.
Using atomic clocks, scientists are able to establish the effect Earth’s gravity has on time. The high above sea level an atomic clock is placed, the quicker time travels. While these differences are minute, these experiments clearly demonstrate that Einstein’s postulations were correct.
Atomic clocks have been used to demonstrate some of Einstein’s other theories regarding time too. In his theories of relativity, Einstein argued that speed is another factor that affects the speed at which time passes. By placing atomic clocks on orbiting spacecraft or aeroplanes travelling at speed, the time measured by these clocks differs to clocks left static on Earth, another indication that Einstein was right.
Before atomic clocks, measuring time to such degrees of accuracy was impossible, but since their invention in the 1950’s, not only have Einstein’s postulations proved right, but also we have discovered some other unusual aspects to how we regard time.
While most of us think of a day as 24-hours, with every day being the same length, atomic clocks have shown that each day varies. Furthermore, atomic clocks have also shown that the Earth’s rotation is gradually slowing down, meaning that days are getting slowly longer.
Because of these changes to time, the world’s global timescale, UTC (Coordinated Universal Time) needs occasional adjustments. Every six months or so, leap seconds are added to ensure UTC runs at the same rate as an Earth day, accounting for the gradual slowing down of the planet’s spin.
For technologies that require high levels of accuracy, these regular adjustments of time are accounted for by the time protocol NTP (Network Time Protocol) so a computer network using an NTP time server is always kept true to UTC.
Researchers have discovered that the British atomic clock controlled by the UK’s National Physical Laboratory (NPL) is the most accurate in the world.
NPL’s CsF2 caesium fountain atomic clock is so accurate that it wouldn’t drift by a second in 138 million years, nearly twice as accurate as first thought.
Researchers have now discovered the clock is accurate to one part in 4,300,000,000,000,000 making it the most accurate atomic clock in the world.
The CsF2 clock uses the energy state of caesium atoms to keep time. With a frequency of 9,192,631,770 peaks and troughs every second, this resonance now governs the international standard for an official second.
The international standard of time—UTC—is governed by six atomic clocks, including the CsF2, two clocks in France, one in Germany and one in the USA, so this unexpected increase in accuracy means the global timescale is even more reliable than first thought.
UTC is essential for modern technologies, especially with so much global communication and trade being conducted across the internet, across borders, and across timezones.
UTC enables separate computer networks in different parts of the world to keep exactly the same time, and because of its importance accuracy and precision is essential, especially when you consider the types of transactions now conducted online, such as the buying of stocks and shares and global banking.
Receiving UTC requires the use of a time server and the protocol NTP (Network Time Protocol). Time servers receive a source of UTC direct from atomic clocks sources such as NPL, who broadcast a time signal over long wave radio, and the GPS network (GPS satellites all transmit atomic clock time signals, which is how satellite navigation systems calculate position by working out the difference in time between multiple GPS signals.)
NTP keeps all computers accurate to UTC by continuously checking each system clock and adjusting for any drift compared to the UTC time signal. By using an NTP time server, a network of computers is able to remain within a few milliseconds of UTC preventing any errors, ensuring security and providing an attestable source of accurate time.
Most of us recognise how long an hour, a minute, or a second is, and we are used to seeing our clocks tick past these increments, but have you ever thought what governs clocks, watches and the time on our computers to ensure that a second is a second and an hour an hour?
Early clocks had a very visible form of clock precision, the pendulum. Galileo Galilei was the first to discover the effects of weight suspended from a pivot. On observing a swinging chandelier, Galileo realised that a pendulum oscillated continuously above its equilibrium and didn’t falter in the time between swings (although the effect weakens, with the pendulum swinging less far, and eventually stops) and that a pendulum could provide a method of keeping time.
Early mechanical clocks that had pendulums fitted proved highly accurate compared to other methods tried, with a second able to be calibrated by the length of a pendulum.
Of course, minute inaccuracies in measurement and effects of temperature and humidity meant that pendulums were not wholly precise and pendulum clocks would drift by as much as half an hour a day.
The next big step in keeping track of time was the electronic clock. These devices used a crystal, commonly quartz, which when introduced to electricity, will resonate. This resonance is highly precise which made electric clocks far more accurate than their mechanical predecessors were.
True accuracy, however, wasn’t reached until the development of the atomic clock. Rather than using a mechanical form, as with a pendulum, or an electrical resonance as with quartz, atomic clocks use the resonance of atoms themselves, a resonance that doesn’t change, alter, slow or become affected by the environment.
In fact, the International System of Units that define world measurements, now define a second as the 9,192,631,770 oscillations of a caesium atom.
Because of the accuracy and precision of atomic clocks, they provide the source of time for many technologies, including computer networks. While atomic clocks only exist in laboratories and satellites, using devices like Galleon’s NTS 6001 NTP time server.
A time server such as the NTS 6001 receives a source of atomic clock time from either GPS satellites (which use them to provide our sat navs with a way to calculate position) or from radio signals broadcast by physics laboratories such as NIST (National Institute of Standards and Time) or NPL (National Physical Laboratory).
If you’ve ever tried to keep track of time without a watch or clock, you’ll realise just how difficult it can be. Over a few hours, you may get to within half an hour of the right time, but precise time is very difficult to measure without some form of chronological device.
Before the use of clocks, keeping time was incredibly difficult, and even losing track of days of the years became easy to do unless you kept as daily tally. But the development of accurate timepieces took a long time, but several key steps in chronology evolved enabling closer and closer time measurements.
Today, with the benefit of atomic clocks, NTP servers and GPS clock systems, time can be monitored to within a billionth of a second (nanosecond), but this sort of accuracy has taken mankind thousands of years to accomplish.
With no appointments to keep or a need to arrive at work on time, prehistoric man had little need for knowing the time of day. But when agriculture started, knowing when to plant crops became essential for survival. The first chronological devices such as Stonehenge are believed to have been built for such a purpose.
Identifying the longest and shortest days of the year (solstices) enabled early farmers to calculate when to plant their crops, and probably provided a lot of spiritual significance to such events.
The provided the first attempts at keeping track of time throughout the day. Early man realised the sun moved across the sky at regular paths so they used it as a method of chronology. Sundials came in all sorts of guises, from obelisks that cast huge shadows to small ornamental sundials.
The first true attempt at using mechanical clocks appeared in the thirteenth century. These used escapement mechanisms and weights to keep time, but the accuracy of these early clocks meant they’d lose over an hour a day.
Clocks first became reliable and accurate when pendulums began appearing in the seventeenth century. While they would still drift, the swinging weight of pendulums meant that these clocks could keep track of first minutes, and then the seconds as engineering developed.
Electronic clocks using quartz or other minerals enabled accuracy to parts of a second and enabled scaling down of accurate clocks to wristwatch size. While mechanical watches existed, they would drift too much and required constant winding. With electronic clocks, for the first time, true hassle free accuracy was achieved.
Keeping time to thousands, millions and even billion parts of a second came when the first atomic clocks arrived in the 1950’s. Atomic clocks were even more accurate than the rotation of the Earth so Leap Seconds needed developing to make sure the global time based on atomic clocks, Coordinated Universal Time (UTC) matched the path of the sun across the sky.
The argument about the use of the Leap Second continues to rumble on with astronomers again calling for the abolition of this chronological ‘fudge.’
The Leap Second is added to Coordinated Universal Time to ensure the global time, coincides with the movement of the Earth. The problems occur because modern atomic clocks are far more precise than the rotation of the planet, which varies minutely in the length of a day, and is gradually slowing down, albeit minutely.
Because of the differences in time of the Earth’s spin and the true time told by atomic clocks, occasional seconds need adding to the global timescale UTC—Leap Seconds. However, for astronomers, leap seconds are a nuisance as they need to keep track of both the Earth’s spin—astronomical time—to keep their telescopes fixed on studied objects, and UTC, which they need as atomic clock source to work out the true astronomical time.
Next year, however, a group of astronomical scientists and engineers, plan to draw attention to the forced nature of Leap Seconds at the World Radiocommunication Conference. They say that as the drift caused by not including leap seconds would take such a long time—probably over a millennia, to have any visible effect on the day, with noon gradually shifting to afternoon, there is little need for Leap Seconds.
Whether Leap Seconds remain or not, getting an accurate source of UTC time is essential for many modern technologies. With a global economy and so much trade conducted online, over continents, ensuring a single time source prevents the problems different time-zones could cause.
Making sure everybody’s clock reads the same time is also important and with many technologies millisecond accuracy to UTC is vital—such as air traffic control and international stock markets.
NTP time servers such as Galleon’s NTS 6001 GPS, which can provide millisecond accuracy using the highly precise and secure GPS signal, enable technologies and computer networks to function in perfect synchronicity to UTC, securely and without error.
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.