Archive for January, 2011

Mechanisms of Time History of Chronological Devices

Wednesday, January 26th, 2011

Nearly every device seems to have a clock attached to it these days. Computers, mobile phones and all the other gadgets we use are all good sources of time. Ensuring that no matter where you are a clock is never that far away – but it wasn’t always this way.

Clock making, in Europe, started around the fourteenth century when the first simple mechanical clocks were developed. These early devices were not very accurate, losing perhaps up to half an hour a day, but with the development of pendulums these devices became increasingly more accurate.

However, the first mechanic al clocks were not the first mechanical devices that could tell and predict time. Indeed, it seems Europeans were over fifteen hundred years late with their development of gears, cogs and mechanical clocks, as the ancients had long ago got there first.

Early in the twentieth century a brass machine was discovered in a shipwreck (Antikythera wreck) off Greece, which was a device as complex as any clock made in Europe up in the mediaeval period. While the Antikythera mechanism is not strictly a clock – it was designed to predict the orbit of planets and seasons, solar eclipses and even the ancient Olympic Games – but is just as precise and complicated as Swiss clocks manufactured in Europe in the nineteenth century.

While Europeans had to relearn the manufacture of such precise machines, clock making has moved on dramatically since then. In the last hundred or so years we have seen the emergence of electronic clocks, using crystals such as quartz to keep time, to the emergence of atomic clocks that use the resonance of atoms.

Atomic clocks are so accurate they won’t drift by even a second in a hundred thousand years which is phenomenal when you consider that even quartz digital clocks will drift several seconds n a day.

While few people will have ever seen an atomic clock as they are bulky and complicated devices that require teams of people to keep them operational, they still govern our lives.

Much of the technologies we are familiar with such as the internet and mobile phone networks, are all governed by atomic clocks. NTP time servers (Network Time Protocol) are used to receive atomic clock signals often broadcast by large physics laboratories or from the GPS (Global Positioning System) satellite signals.

NTP servers then distribute the time around a computer network adjusting the system clocks on individual machines to ensure they are accurate. Typically, a network of hundreds and even thousands of machines can be kept synchronised together to an atomic clock time source using a single NTP time server, and keep them accurate to within a few milliseconds of each other (few thousandths of a second).

How Atomic Clocks Control our Transport Systems

Wednesday, January 19th, 2011

Getting from A to B has been a primary concern for societies ever since the first roads were built. Whether it is horseback, carriage, train, car or plane – transportation is what enables societies to grow, prosper and trade.

In today’s world, our transportation systems are highly complex due to the sheer numbers of people who are all trying to get somewhere – often at similar times such as rush hour. Keeping the motorways, highways and railways running, requires some sophisticated technology.

Traffic lights, speed cameras, electronic warning signs, and railway signals and point systems have to be synchronised for safety and efficiency. Any differences in time between traffic signals, for instance, could lead to traffic queues behind certain lights, and other roads remaining empty. While on the railways, if points systems are being controlled by an inaccurate clock, when the trains arrive the system may be unprepared or not have switched the line – leading to catastrophe.

Because of the need for secure, accurate and reliable time synchronisation on our transport systems, the technology that controls them is often synchronised to UTC using atomic clock time servers.

Most time servers that control such systems have to be secure so they make use of Network Time Protocol (NTP) and receive a secure time transmission either utilising atomic clocks on the GPS satellites (Global Positioning System) or by receiving a radio transmission from a physics laboratory such as NPL (National Physical Laboratory) or NIST (National Institute of Standards and Time).

In doing so, all traffic and rail management systems that operate on the same network are accurate to each other to within a few milliseconds of this atomic clock generated time and the NTP time servers that keep them synchronised ensures they stay that way, making minute adjustments to each system clock to cope with the drift.

NTP servers are also used by computer networks to ensure that all machines are synced together. By using a NTP time server on a network, it reduces the probability of errors and ensures the system is kept secure.

UTC One Time to Rule Them All

Wednesday, January 12th, 2011

In a global economy time has become a more crucial than ever before. As people across the globe, communicate, conference and buy and sell from each other, being aware of the each other’s time is vital for conducting business successfully.

And with the internet, global communication and time awareness are even more important as computers require a source of time for nearly all their applications and processes. The difficulty with computer communication, however, is that if different machines are running different times, all sorts of errors can occur. Data can get lost, errors fail to log; the system can become unsecure, unstable and unreliable.

Time synchronisation for computer networks communicating with each other is, therefore, essential – but how is it achieved when different networks are in different time-zones?

The answer lies with Universal Coordinated Time (UTC) an international time-zones developed in the 1970’2 that is based on accurate atomic clocks.  UTC is set the same the world over, with no accounting for time-zones so the time on a network in the UK – will be identical to the network time in the USA.

UTC time on a computer network is also kept synchronised through the use of NTP (Network Time Protocol) and an NTP server.  NTP ensures all devices on a networked system have exactly the right time as different computer clocks will drift at varying rates – even if the machines are identical.

While UTC makes no accounting for time-zones system clocks can still be set to the local time-zone but the applications and functions of a computer will use UTC.

UTC time is delivered to computer networks through a variety of sources: radio signals, the GPS signal, or across the internet (although the accuracy of internet time is debatable). Most computer networks have a NTP time server somewhere in their server room which will receive the time signal and distribute it through the network ensuring all machines are within a few milliseconds of UTC and that the time on your network corresponds to every other UTC network on the globe.

Computer Time Synchronisation The Basics

Wednesday, January 5th, 2011

With so much automated in the modern world and with computer networks running everything from finance to health services, keeping, storing and transferring information needs to be secure, accurate and reliable.

The time is crucial for computer systems to ensure this. Timestamps are the only information computers have to assess if a task has been completed, is due, or that information has been successfully received, sent or stored. One of the most common causes of computer errors comes from inadequate synchronisation of timings.

All computer networks need to be synchronised, and not just all the devices on a network, either. With so much global communication these days, all computer networks across the globe need to be synchronised together, otherwise when they communicate errors may occur, data can get lost, and it can pave the way for security problems as time discrepancies can be used by malicious users and software.

But how do computers synchronise together? Well, it is made possible by to innovations. The first is the international timescale, UTC (Coordinated Universal Time), kept true by atomic clocks and the same the world over, regardless of time-zones. The second, NTP (Network Time Protocol) is a computer program designed to keep PCs synchronised together.

Both NTP and UTC operate in tandem. The computer time server (NTP server) receives a UTC time source, either from radio, GPS (Global Positioning System) or the internet (although an insecure method of receiving UTC and not recommended).

NTP then distributes this time around a network, checking the time on each device at periodic intervals and adjusts them for any drift in time. Most computer networks that utilise NTP time servers in this way have each machine on the network within milliseconds of UTC time, enabling accurate and precise global communication.

NTP time servers are the only secure and accurate method of computer network synchronisation and should be used by any computer system that requires reliability, accuracy and security.