The UK MSF signal is operated by NPL – the National Physical Laboratory. MSF has high transmitter power (50,000 watts), a very efficient antenna and an extremely low frequency (60,000 Hz). For comparison, a typical AM radio station broadcasts at a frequency of 1,000,000 Hz. The combination of high power and low frequency gives the radio waves from MSF a lot of bounce, and this single station can therefore cover most of Britain and some of continental Europe.

The time codes are sent from MSF using one of the simplest systems possible, and at a very low data rate of one bit per second. The 60,000 Hz signal is always transmitted, but every second it is significantly reduced in power for a period of 0.2, 0.5 or 0.8 seconds: • 0.2 seconds of reduced power means a binary zero • 0.5 seconds of reduced power is a binary one. • 0.8 seconds of reduced power is a separator. The time code is sent in BCD (Binary Coded Decimal) and indicates minutes, hours, day of the year and year, along with information about daylight savings time and leap years.

The time is transmitted using 53 bits and 7 separators, and therefore takes 60 seconds to transmit. A clock or watch can contain an extremely small and relatively simple antenna and receiver to decode the information in the signal and set the clock’s time accurately. All that you have to do is set the time zone, and the atomic clock will display the correct time.

Dedicated time servers that are tuned to receive the MSF time signal are available. These devices connect o a computer network like any other server only these receive the timing signal and distribute it to other machines on the network using NTP (Network Time Protocol).

All computers have an on-board clock that provides time and date information. These Real Time Clock (RTC) chips are battery backed so that even when off they can maintain time, however these RTC chips are mass produced and cannot maintain accurate time and tend to drift.

For many applications this can be quite adequate, however if a computer is on a network and needs to talk to other machines, failing to be synchonised to the correct time can mean many time-sensitive transactions can not be completed and can even leave the network open to security threats.

All versions of Windows Server since 2000 have included a time synchronization facility, called Windows Time Service (w32time.exe), built into the operating system. This can be configured to operate as a network time server synchronizing all machines to a specific time source.

Windows Time Service uses a version of NTP (Network Time Protocol), normally a simplified version, of the Internet protocol which is designed to synchronise machines on a network, NTP is also the standard for which most computer networks across the global use to synchronise with.

Choosing the correct time source is vitally important. Most networks are synchronized to UTC (Coordinated Universal Time) source. UTC is a global standardized time based on atomic clocks which are the most accurate time sources.

UTC can be obtained over the Internet from such places as time.nist.gov (us Naval Observatory) or time.windows.com (Microsoft) but it must be noted that internet time sources can not be authenticated which can leave a system open to abuse and Microsoft and others advise using an external hardware source as a reference clock such as a specialized NTP server.

NTP servers receive their time source from either a specialist radio transmission from national physics laboratories which broadcast UTC time taken from an atomic clock source or by the GPS network which also relays UTC as a consequence of needing it to pin point locations.

NTP can maintain time over the public Internet to within 1/100th of a second (10 milliseconds) and can perform even better over LANs.

Currently NTP is used to synchonise computer networks using network time servers (NTP servers). Currently NTP can synchronise a computer network to a few milliseconds.

The Precision Time Protocol (PTP) or IEEE 1588 has been developed for local systems requiring very high accuracy (to nano-second level). Currently this type of accuracy is beyond the capabilities of NTP.

PTP requires a master and slave relation ship in the network. A two-step process is required to synchronise devices using the IEEE 1588 (PTP). First, determination of which device is the master is required then the offsets and natural network delays are measured. PTP uses the Best Master Clock algorithm (BMC) to establish which clock on the network is the most accurate and it becomes the master whilst all other clocks become slaves and synchronise to this master.

IEEE (Institute of Electrical and Electronic Engineers) describes IEEE 1588 or (PTP) as designed to “fill a niche not well served by either of the two dominant protocols, NTP and GPS. IEEE 1588 is designed for local systems requiring very high accuracies beyond those attainable using NTP. It is also designed for applications that cannot bear the cost of a GPS receiver at each node, or for which GPS signals are inaccessible.” (quoted in Wikipedia)

PTP can provide accuracy to a few nano-seconds but this type of accuracy is not required by most network users however, the target use of PTP appears to be mobile broadband and other mobile technologies as PTP supports time-of-day information, used by billing and service level agreement reporting functions in mobile networks.

Who decides when clocks should go forward or back for summer time?

If you live in Europe, the time at which summer time begins and ends is given in the relevant EU Directive and UK Statutory Instrument as 1 a.m. Greenwich Mean Time (GMT).

Does ‘midnight’ belong to the day before or the day after?

The use of the word midnight is heavily dependent on its context but 00.00 (often called 12 am) is the start of the next day. There are no standards established for the meaning of 12 a.m. and 12 p.m. and often a 24 hour time is less confusing.

Is there an approved way to represent dates and times?

The standard notation for the date is the sequence YYYY-MM-DD or YY-MM-DD although in the USA it is the convention to have days and months the other way around.

When did the new millennium really begin?

A millennium is any period of a thousand years. So you could say that the next millennium begins now. The third millennium of the Christian Era began at the start of the year 2001 A.D.

How do you know atomic clocks keep better time?

If you look at several atomic clocks all set to the same time you’ll find that they still agree within ten millionths of a second after a week.

What is the accuracy of the ‘speaking clock’?

Even allowing for the delay in the telephone network, you can probably expect the starts of the seconds pips to be accurate seconds markers within about one-tenth of a second.

Why did my radio-controlled clock move to summer time at 2 a.m., one hour late?

Battery powered radio-controlled clocks typically check the time only every hour or two, or even less, This is to conserve the battery.

Why does my radio-controlled clock receive the MSF signal less well at night?

Users of the MSF service receive predominantly a ‘ground wave’ signal. However, there is also a residual ‘sky wave’ which is reflected off the ionosphere and is much stronger at night, this can result in a total received signal that is either stronger or weaker.

Is there a permanent one-hour difference between MSF time and DCF-77 time?

Since 1995 October 22 there has been a permanent one-hour difference between British time (as broadcast by MSF) and Central European Time, as broadcast by DCF-77 in Germany.

What does MSF stand for?

MSF is the three-letter call sign used to designate the UK’s 60 kHz standard-frequency and time signal.

Thanks to the National Physical Laboratory for their help with this blog.

Thanks to atomic clocks many technologies have become possible and have changed the way we live our lives. Satellite communication, satellite navigation, internet shopping and network communication are only possible thanks to atomic clocks.

Atomic clocks are the basis for the world’s global timescale Universal Coordinated Time (UTC) and are the reference that many computer networks use as a time source to distribute amongst its devices using NTP (Network Time Protocol) and a time server.

Atomic clocks are based on the atom caesium -133. This element has been traditionally used in atomic clocks as its resonance or vibrations during a particular energy state, or extremely high (over 9 billion) and therefore can provide high levels of accuracy.

However, new types of atomic clocks are on the horizon that will boast even more accuracy with the next generation of atomic clocks neither gaining nor losing a second in 200 million years.

The next generation of atomic clocks no longer rely on the caesium atom but use elements such as mercury or strontium and instead of using microwaves such as the caesium clocks these new clocks use light which has higher frequencies.

Strontium’s resonance also exceeds over 430 trillion which is vastly superior to the 9.2 billion vibrations that caesium manages.

Currently atomic clocks can be utilised by computer systems by using either a radio or GPS clock or dedicated NTP time server. These devices can receive the time signal transmitted by atomic clocks and distribute them amongst network devices and computers.

However, the National Institute for Standards and Technology (NIST) have revealed a miniature atomic clock that measures just 1.5 millimetres on a side and about 4 millimetres tall. It consumes less than 75 thousandths of a watt, and has a stability of about one part in 10 billion, equivalent to a clock that would neither gain nor lose more than a second in 300 years.

In the future these devices could be integrated into computer systems, replacing the current real time clock chips, which are notoriously inaccurate and can drift.

Most methods of timekeeping have traditionally been based on the movement of the Earth around the Sun. For millennia, a day has been divided into 24 equal parts that have become known as hours. Basing our timescales on the rotation of the Earth has been adequate for most of our historical needs, however as technology advances, the need for an ever increasingly accurate timescale has been evident.

The problem with the traditional methods became apparent when the first truly accurate timepieces – the atomic clock was developed in the 1950’s. Because these timepieces was based on the frequency of atoms and were accurate to within a second every million years it was soon discovered that our day, that we had always presumed as being precisely 24 hours, altered from day to day.

The affects of the Moon’s gravity on our oceans causes the Earth to slow and speed up during its rotation – some days are longer than 24 hours whilst others are shorter. Whilst this minute differences in the length of a day have made little difference to our daily lives it this inaccuracy has implications for many of our modern technologies such as satellite communication and global positioning.

A timescale has been developed to deal with the inaccuracies in the Earth’s spin – Coordinated Universal Time (UTC). It is based on the traditional 24-hour Earth rotation known as Greenwich Meantime (GMT) but accounts for the inaccuracies in the earth’s spin by having so-called ‘Leap Seconds’ added (or subtracted).

As UTC is based on the time told by atomic clocks it is incredibly accurate and therefore has been adopted as the World’s civilian timescale and is used by business and commerce all over the globe.

Most computer networks can be synchronised to UTC by using a dedicated NTP time server.

Most wall clocks are not very accurate. Set two clocks to the same time and after a week or so, the clocks could be a minute or so apart, and over several weeks there could be as much as ten minutes difference between the clocks. Of course, constant resetting and synchronisation is one solution, but that means somebody has to take charge of synchronising an organisations clocks, which in a large building could me quite a task. Fortunately, NTP POE wall clocks are the ideal solution for maintaining accurate, precise and synchronised time.

Network Time Protocol

NTP POE wall clocks use Network Time Protocol (NTP) to maintain accuracy and synchronisation. NTP is a computer algorithm that works by taking a single master time source that it distributes to all devices on a network. In the case of most NTP systems, the time is received via a NTP time server that is hooked up to a computer network.
All computer networks need an accurate source of time for security and preventing errors. This time source typically comes from an atomic clock source, usually received by the NTP server by either GPS or a radio signal. NTP then checks all devices, including NTP POE wall clocks, and continuously adjusts them to ensure they exactly match this master time source.

Power Over Ethernet

NTP POE wall clocks are connected to a computer network using an Ethernet cable. They don’t require batteries because they utilise power over Ethernet, a system that provides both data and power to run the clocks.
Power over Ethernet is an efficient system that is easy to install and means clocks can maintain time without fear of batteries running down or having to use the services of an electrician to wire the clocks to the mains.

POE Clocks

Once installed and connected to the network, a NTP POE wall clock will set itself, taking the time directly from the NTP time server. This means the clock will be accurate to an atomic clock source. Furthermore, all NTP POE wall clock installed on the network will always have the exact same time, ensuring that everybody in a large organisation can have access to a precise source of time.

Once installed, a NTP POE wall clock will never have to be manually set. Even daylight saving hours will be accounted for with the clocks automatically setting themselves to the exact time. Easy to install, an NTP POE wall clock is the ideal solution for providing accurate, precise and visible time around large organisations.

NTP on will synchronise your computer’s clock to a pool of time servers around the world that are official ‘timekeepers’. It is best to choose the closest to you so response time is minimized and to use more than one in case one goes down. There are more than 1.500 servers to choose from, but some areas are better served than others. Many servers on the internet are extremely inaccurate and Internet time references should not be used as a replacement for a dedicated time server.

However, for basic time synchronisation purposes, Internet providers will suffice. The first step should be to select three servers close to you – preferably in your country, or if there aren’t enough, in your ‘zone. Go to ntp home and browse through the tree of zones and servers to select which ones are best for you. The follow these commands to configure:

1. Configure /etc/ntp.conf
Edit this file with a text-editor. Replace
server
with your servers, such as:

server 0.br.pool.ntp.org
server 1.br.pool.ntp.org
server 2.br.pool.ntp.org

2. Synchronise your clock manually
If your clock is drifting too NTP might refuse to synchronise it, but it can be done manually:

ntpdate 0.br.pool.ntp.org (server name that you choose)

3. Make your ntp daemon executable

chmod +x /etc/rc.d/rc.ntpd

4. Start NTP now without rebooting
Again, a simple command:

/etc/rc.d/rc.ntpd start

The North American WWVB signal is operated by NIST – the National Institute of Standards and Technology. WWVB has high transmitter power (50,000 watts), a very efficient antenna and an extremely low frequency (60,000 Hz). For comparison, a typical AM radio station broadcasts at a frequency of 1,000,000 Hz. The combination of high power and low frequency gives the radio waves from WWVB a lot of bounce, and this single station can therefore cover the entire continental United States plus much of Canada and Central America.

The time codes are sent from WWVB using one of the simplest systems possible, and at a very low data rate of one bit per second. The 60,000 Hz signal is always transmitted, but every second it is significantly reduced in power for a period of 0.2, 0.5 or 0.8 seconds: • 0.2 seconds of reduced power means a binary zero • 0.5 seconds of reduced power is a binary one. • 0.8 seconds of reduced power is a separator. The time code is sent in BCD (Binary Coded Decimal) and indicates minutes, hours, day of the year and year, along with information about daylight savings time and leap years.

The time is transmitted using 53 bits and 7 separators, and therefore takes 60 seconds to transmit. A clock or watch can contain an extremely small and relatively simple antenna and receiver to decode the information in the signal and set the clock’s time accurately. All that you have to do is set the time zone, and the atomic clock will display the correct time.

Dedicated NTP time servers that are tuned to receive the WWVB time signal are available. These devices connect o a computer network like any other server only these receive the timing signal and distribute it to other machines on the network using NTP (Network Time Protocol).

Its probably not hard to imagine what people think of as the most life-changing inventions: the Internet, mobile phones, satellite navigation systems, media players etc.

However, nearly all theses technologies rely on accurate and precise time and they would not function without it. The atomic clocks lies at the heart of many of the modern innovations, technologies and applications associated with them.

Let’s take the Internet as an example. The Internet is, in its simplest form, a global network of computers, and this network spans time zones and countries. Now consider some of the things we use the Internet for: online auctions, Internet banking or seat reservation for example. These transactions could not be possible with precise and accurate time and synchronisation.

Imagine booking a seat on an airline at 10am and then another customer tries to book the same seat after you on a computer with a slower clock. The computer only has the time to go on so will consider the person who booked after you to have been the first customer because the clock says so! This is the reason any Internet network that requires time sensitive transactions is connected to a NTP server to receive and distribute an atomic clock time signal.

And for other technologies the atomic clock is even more crucial. Satellite navigation (GPS) is a prime example. GPS (Global Positioning System) works by triangulating atomic clock signals from satellites. Because of the high velocity of radio waves an inaccuracy of 1 second could see a sat-nav device out by 100,000 km.

Other technologies too from mobile phone networks to air traffic control systems are completely reliable on atomic clocks demonstrating how underrated this technology is.