Archive for the ‘timing source’ Category

Keeping Track of Time Zones

Wednesday, October 19th, 2011

Despite the use of UTC (Coordinated Universal Time) as the world’s timescale, time zones, the regional areas with a uniform time, are still an important aspect of our daily lives. Time zones provide areas with a synchronised time that helps commerce, trade and society function, and allow all nations to enjoy noon at lunchtime. Most of us who have ever gone abroad are all aware of the differences in time zones and the need to reset our watches.

Time zones around the world

Keeping track of time zones can be really tricky. Different nations not only use different times but also use different adjustments for daylight saving, which can make keeping track of time zones difficult. Furthermore, nations occasionally move time zone, normally due to economic and trade reasons, which provides even more difficulties in keeping track of time zones.

You may think that modern computers can automatically account for time zones due to the settings in the clock program; however, most computer systems rely on a database, which is continuously updated, to provide accurate time zone information.

The Time Zone Database, sometimes called the Olson database after its long-time coordinator, Arthur David Olson, has recently moved home due to legal wrangling, which temporarily caused the database to cease functioning, causing untold problems for people needing accurate time zone information. Without the time zone database, time zones had to be calculated manually, for travelling, scheduling meetings and booking flights.

The Internet’s address system, ICANN (Internet Corporation for Assigned Names and Numbers) has taken over the database to provide stability, due to the reliance on the database by computer operating systems and other technologies; the database is used by a range of computer operating systems including Apple Inc’s Mac OS X, Oracle Corp, Unix and Linux, but not Microsoft Corp’s Windows.

The Time Zone Database provides a simple method of setting the time on a computer, enabling cities to be selected, with the database providing the right time. The database has all the necessary information, such as daylight saving times and the latest time zone movements, to provide accuracy and a reliable source of information.

Or course, a synchronised computer networks using NTP doesn’t require the Time Zone Database. Using the standard international timescale, UTC, NTP servers maintain the exact same time, no matter where the computer network is in the world, with the time zone information calculated as a difference to UTC.

 

 

Vote Called to End the Use of GMT and Scrapping the Leap Second

Wednesday, October 12th, 2011

International Telecommunications Union (ITU), based in Geneva, is voting in January to finally get rid of the leap second, effectively scrapping Greenwich Meantime.

 

Greenwich Mean Time may come to an end

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.

Google Finds Innovative Way to Avoid Leap Seconds

Wednesday, September 28th, 2011

Leap Seconds have been in use since the development of atomic clocks and the introduction of the global timescale UTC (Coordinated Universal Time). Leap Seconds prevent the actual time as told by atomic clocks and the physical time, governed by the sun being highest at noon, from drifting apart.

Since UTC began in the 1970’s when UTC was introduced, 24 Leap Seconds have been added. Leap seconds are a point of controversy, but without them, the day would slowly drift into night (albeit after many centuries); however, they do cause problems for some technologies.

NTP servers (Network Time Protocol) implement Leap Seconds by repeating the final second of the day when a Leap Second is introduced. While Leap Second introduction is a rare event, occurring only once or twice a year, for some complex systems that process thousands of events a second this repetition causes problems.

For search engine giants, Google, Leap Seconds can lead to their systems from working during this second, such as in 2005 when some of its clustered systems stopped accepting work. While this didn’t lead to their site from going down, Google wanted to address the problem to prevent any future problems caused by this chronological fudge.

Its solution was to write a program that essentially lied to their computer servers during the day of a Leap Second, making the systems believe the time was slightly ahead of what the NTP servers were telling it.

This gradual speeding up time meant that at the end of a day, when a Leap Second is added, Google’s timeservers do not have to repeat the extra second as the time on its servers would already be a second behind by that point.

Galleon GPS NTP server

Whilst Google’s solution to the Leap Second is ingenious, for most computer systems Leap Seconds cause no problems at all. With a computer network synchronised with an NTP server, Leap Seconds are adjusted automatically at the end of a day and occur only rarely, so most computer systems never notice this small hiccup in time.

 

Precise Time on the Markets

Wednesday, August 10th, 2011

The stock market has been in the news a lot lately. As global uncertainty about national debts rise, the markets are in flux, with prices changing incredibly quickly. On a trading floor, every second counts and precise time is essential for global buying and selling of commodities, bonds and shares.

NTS 6001 from Galleon Systems

The international stock exchanges such as the NASDAQ and London Stock Exchange all require accurate and precise time. With traders buying and selling shares for customers across the globe, a few seconds of inaccuracy could cost millions as share prices fluctuate.

NTP servers linked to atomic clock timing signals ensure that the stock exchange keeps an accurate and precise time. As computers across the globe all receive the stock prices, as and when they change, these two use NTP server systems to maintain time.

The global timescale UTC (Coordinated Universal Time) is used as the basis for atomic clock timing, so no matter where a trader is on the globe, the same timescale prevents confusion and errors when dealing with stocks and shares.

Because of the billions of pounds worth of stocks and shares that are bought and sold on trading floors every day, security is essential. NTP servers work externally to networks, getting their time from sources such as GPS (Global Positioning System) or radio signals put out by organisations like the National Physical Laboratory (NPL) or the National Institute for Standards and Time (NIST).

The stock exchanges can’t use a source of internet because of the risk this could pose. Hackers and malicious users could tamper with the time source, leading to mayhem and cost millions and perhaps billions if the wrong time was spread around the exchanges.

The precision of internet time is limited too. Latency over distance can create delays, which could lead to errors, and if the time source ever went down, the stock markets could hit trouble.

It is not only stock markets that need precise and accurate time, computer networks across the globe concerned about security use dedicated NTP servers like Galleon Systems’ NTS 6001. Providing accurate time from both GPS and radio signals from NPL and NIST, the NTS 6001 ensure accurate, precise and secure time every day of the year.

 

A Guide to Securing Computer Networks in Business

Thursday, June 23rd, 2011

Security is an essential aspect for any computer network. With so much data now available online, giving ease of access to permitted users, it is important to prevent unauthorised access. Failure to secure a computer network can lead to all sorts of problems for a business, such as data theft, or the network crashing and preventing authorised users from working.

Most computer networks have a firewall, which controls access. A firewall is perhaps the first line of defence in preventing unauthorised access, as it can screen and filter traffic attempting to get on to the network.

All traffic attempting to gain access to the network has to pass through the firewall; however, not all unauthorised attempts to gain access to a network is from people, malicious software is often used to gain access to data or disrupt a compute network, and often these programs can get past this first line of defence.

Different forms of malicious software can gain access to computer networks, and include:

  • Computer Viruses and Worms

These can change or replicate existing files and programs. Computer viruses and worms often steal data and send it to unauthorised users.

  • Trojans

Trojans appear as harmless software but contains viruses or other malicious software hidden in the program and are often downloaded by people thinking they are normal and benign programs.

  • Spyware

Computer programs that spy on the network, reporting to unauthorised users. Often spyware can run undetected for a long time.

  • Botnet

A botnet is a collection of computers taken over and used to perform malicious tasks. A computer network can fall victim to a botnet or unwillingly become part of one.

Other threats

Computer networks are attacked in other ways too, such as bombarding the network with access requests. These targeted attacks, called denial-of-service attacks (DDoS attack), can prevent normal use as the network slows down as it tries to deal with all attempts at access.

Protecting Against Threats

Besides the firewall, antivirus software forms the next line of defence against malicious programs. Designed to detect these types of threats, these programs remove or quarantine malicious software before they can do damage to the network.

Antivirus software is essential for any business network and needs regular updating to make sure the program is familiar with all the latest types of threats.

Another essential method for ensuring security is to establish accurate synchronisation of the network. Making sure all machines are running the exact same time will prevent malicious software and users from taking advantage of time lapses. Synchronising to a NTP server (Network Time Protocol) is a common method of ensuring synchronised time. While many NTP servers exist online, these are not very secure as malicious software can hijack the time signal and enter the computer firewall via the NTP port.

Furthermore, online NTP servers can also be attacked leading to the incorrect time being sent to computer networks that access the time from them. A more secure method of getting precise time is to use a dedicated NTP server that works externally to the computer network and receives the time from a GPS (Global Positioning System) source.

 

Summer Solstice The Longest Day

Monday, June 20th, 2011

June 21 marks the summer solstice for 2011. The summer solstice is when the Earth’s axis is most inclined to the sun, providing the most amount of sunshine for any day of the year. Often known as Midsummer’s day, marking the exact middle of the summer, periods of daylight get shorter following the solstice.

For the ancients, the summer solstice was an important event. Knowing when the shortest and longest days of the year were important to enable early agricultural civilisations to establish when to plant and harvest crops.

Indeed, the ancient monument of Stonehenge, in Salisbury, Great Britain, is thought to have been erected to calculate such events, and is still a major tourist attraction during the solstice when people travel from all over the country to celebrate the event at the ancient site.

Stonehenge is, therefore, one of the oldest forms of timekeeping on Earth, dating back to 3100BC.While nobody knows exactly how the monument was built, the giant stones were thought to have been transported from miles away—a mammoth task considering the wheel hadn’t even been invented back then.

The building of Stonehenge shows that timekeeping was as important to the ancients as it is to us today. The need for acknowledging when the solstice occurred is perhaps the earliest example of synchronisation.

Stonehenge probably used the setting and rising of the sun to tell the time. Sundials also used the sun to tell the time way before the invention of clocks, but we have come a long way from using such primitive methods in our timekeeping now.

Mechanical clocks came first, and then electronic clocks which were many times more accurate; however, when atomic clocks were developed in the 1950’s, timekeeping became so accurate that even the Earth’s rotation couldn’t keep up and an entirely new timescale, UTC (Coordinated Universal Time) was developed that accounted for discrepancies in the Earth’s spin by having leap seconds added.

Today, if you wish to synchronise to an atomic clock, you need to hook up to a NTP server which will receive an UTC time source from GPS or a radio signal and allow you to synchronise computer networks to maintain 100% accuracy and reliability.

Stonehenge--Ancient timekeeping

Atomic Clocks now Accurate to a Quintillionth of a Second?

Wednesday, June 8th, 2011

Development in clock accuracy seems to increase exponentially. From the early mechanical clocks, there were only accurate to about half an hour a day, to electronic clocks developed at the turn of the century that only drifted by a second. By the 1950’s, atomic clocks were developed that became accurate to thousandths of a second and year on year they have becoming ever more precise.

Currently, the most accurate atomic clock in existence, developed by NIST (National Institute for Standards and Time) loses a second every 3.7 billion years; however, using new calculations researchers suggest they can now come up with a calculation that could lead to an atomic clock that would be so accurate it would lose a second only every 37 billion years (three times longer than the universe has been in existence).

This would make the atomic clock accurate to a quintillionth of a second (1,000,000,000,000,000,000th of a second or 1x 1018). The new calculations that could aid the development of this sort of precision has been developed by studying the effects of temperature on the miniscule atoms and electrons that are used to keep the atomic clocks ‘ticking’. By working out the effects of variables like temperature, the researchers claim to be able to improve the accuracy of atomic clock systems; however, what possible uses does this accuracy have?

Atomic clock accuracy is becoming ever relevant in our high technology world. Not only do technologies like GPS and broadband data streams rely on precise atomic clock timing but studying physics and quantum mechanics requires high levels of accuracy enabling scientists to understand the origins of the universe.

To utilise an atomic clock time source, for precise technologies or computer network synchronisation, the simplest solution is to use a network time server; these devices receive a time stamp direct from an atomic clock source, such as GPS or radio signals broadcast by the likes of NIST or NPL (National Physical Laboratory).

These time servers use NTP (Network Time Protocol) to distribute the time around a network and ensure there is no drift, making it possible for your computer network to be kept accurate to within milliseconds of an atomic clock source.

Network Time Server

 

 

Importance of the GPS Antenna

Monday, April 11th, 2011

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

Wednesday, April 6th, 2011

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.

Our Time and Travel Reliance on GPS

Wednesday, March 23rd, 2011

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