Which time signal? GPS or WWVB and MSF

  |   By

Dedicated NTP time server devices are the easiest, most accurate, reliable and secure method of receiving a source of UTC time (Coordinated Universal Time) for synchronizing a computer network.

NTP servers (Network Time Protocol) operate outside the firewall and are not reliant on the Internet which means they are highly secure and not vulnerable to malicious users who, in the case of Internet time sources can use the NTP client signals as a method of accessing the network or penetrating the firewall.

A dedicated NTP server will also receive it’s time code direct from an atomic clock, this makes it a stratum 1 time server as opposed to online time servers which are stratum 2 time servers, that is they get the time from a stratum 1 server and so are not as accurate.

In using a NTP time server there is only really one decision to make and that is how the time signal is to be received and for this there is only two choices:

The first is to make use of the time standard radio transmissions broadcast by national physics laboratories such as NIST in the USA or the UK’s NPL. These signals (WWVB in the US, MSF in the UK) are limited in range although the USA signal is available in most parts of Canada and Alaska. However, they are vulnerable to local interference and topography as other long wave radio signals are.

The alternative to the WWVB/MSF signal is to utilise the GPS satellite network (Global Positioning System). Atomic clocks are used by GPS satellites as the basis for navigational information used by satellite receivers. These atomic clocks can be used by using a NTP time server fitted with a GPS antenna.

Whilst the GPS time signal is strictly speaking not UTC- it is 17 seconds behind as leap seconds have never been added to GPS time (as the satellites are unreachable) but NTP can account for this (by simply adding 17 whole seconds). The advantage of GPS is that it is available anywhere on the planet just as long as the GPS antenna has a clear view of the sky.

Duel systems that can utilise both types of signal are also available.

The Possibility of Time Travel

  |   By

Exploring the possibilities of time travel including: Time paradoxes, worm holes, 4 dimesnsional space, atomic clocks and NTP servers

Time travel has always been a much loved concept for science fiction writers. From HG Wells’ Time Machine to Back to the Future, travelling forwards or backwards in time has captivated audiences for centuries. However, thanks to the work of modern thinkers like Einstein, it appears that time travel is much a possibility of science fact as it is fiction.

Time travel is not only possible but we do it all the time. Every second that passes is a second further into the future so we are all travelling forward in time. However we think if time travel we imagine a machine that transports individuals hundreds or thousands of years in to the future or past so is that possible.

Well, thanks to Einstein’s theories of general and special relativity, time ravel is certainly possible. We know thanks to the development of atomic clocks that Einstein’s theories about speed and gravity affecting the passage of time is correct. Einstein suggested that gravity would warp space-time (the term he gave to four dimensional space that includes directions plus time) and this has been tested. In fact modern atomic clocks can pick out the minute differences in the passage of time every subsequent inch above the earth’s surface as time speeds up as the effect of the earth’ s gravity weakens.

Einstein predicted speed too would affect time in what he described as time dilation. For any observer travelling close to the speed of light a journey that to an outsider may have taken thousands of years would have passed within seconds. Time dilation means that travelling hundreds of years into the future in a matter of seconds is certainly possible. However, would it be possible to get back again?

This is where many scientists are divided. Strictly speaking theoretical properties of space time do allow for this, although for any travelling back in time a worm hole would have to be created or found. A worm hole is a theoretical link between two parts of space where a traveller could enter one end and appear somewhere completely different at the other end this may be another part of the universe or indeed another point in time.

However, critics of the possibility of time travel point out that because travellers from the future have never visited us that probably means that time travel will never be possible. They also point out the any travelling backwards in time could create paradoxes (what would happen to you if you were mean enough to go back in time and kill your grandparents).

However, time paradoxes exist now. Many computer networks are not synchronised which can lead to errors, loss of data or paradoxes like emails being sent before they were received. To avoid any time crisis it is important for all computer networks to be perfectly synchronised. The best and most accurate method of doing this is to use a NTP time server that receives the time from an atomic clock.

Choosing a Time Source what to do and what not to do

  |   By

Time synchronization is crucial for many of the applications that we do across the internet these days; internet banking, online reservation and even online auctions all require network time synchronization.

Failing to ensure their servers are adequately synchronized would mean many of these applications would be impossible to achieve; seat reservations could be sold more than once, lower bids could win internet auctions and it would be possible to withdraw you life savings from the bank twice if they didn’t have adequate synchronization (good for you not for the bank).

Even computer networks that on the face of it do not rely on time sensitive transactions also need to be adequately synchronized as it could be near impossible to track down errors or protect the system from malicious attacks if the timestamps on differ on various machines on the network.

Many organisations opt to use internet time servers as a source of UTC (Coordinated Universal Time) – the atomic clock controlled global timescale. Although there are many security issues in doing so such as leaving a hole in the firewall to communicate with the time server and not having any authentication for the time synchronization protocol NTP (Network Time Protocol).

However, in saying that many network administrators still opt to use online time servers as a UTC source regardless of the security implications although there are other issues that administrators should be aware of. On the internet there are two types of time server – stratum 1 and stratum 2. Stratum 1 servers receive a time signal direct from an atomic clock while stratum 2 servers receive a time signal from a stratum 1 server. Most internet stratum 1 servers are closed – unavailable to most administrators and there can be some shortfall in accuracy in using a stratum 2 server.

For the most accurate, secure and precise timing information external NTP time servers are the best option as these are stratum 1 devices that can synchronize hundreds of machines on a network to the exact same UTC time.