European Time Synchronisation with DCF-77

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The DCF 77 signal is a long wave transmission broadcast at 77 KHz from Frankfurt in Germany. DCF -77 is transmitted by Physikalisch-Technische Bundesanstalt, the German national physics laboratory.

DCF-77 is an accurate source of UTC time and is generated by atomic clocks that ensure its precision. DCF-77 is a useful source of time that can be adopted all over Europe by technologies needing an accurate time reference.

Radio controlled clocks and network time servers receive the time signal and in the case of time servers distribute this time signal across a computer network. Most computer network use NTP to distribute the DCF 77 time signal.

There are advantages of using a signal like DCF for time synchronisation. DCF is long wave and is therefore susceptible to interference from other electrical devices but they can penetrate buildings that give the DCF signal an advantage over that other source of UTC time generally available – GPS (Global Positioning System) – which requires a open view of the sky to receive satellite transmissions.

Other long wave radio signals are available in other countries that are similar to DCF-77. In the UK the MSF -60 signal is broadcast by NPL (National Physical Laboratory) from Cumbria while in the USA, NIST (National Institute of Standards and Time) transmit the WVBB signal from Boulder, Colorado.

NTP time servers are an efficient method of receiving these long wave transmissions and then using the time code as a synchronisation source. NTP servers can receive DCF, MSF and WVBB as well as many of them also being able to receive the GPS signal too.

MSF Outage 11 June NPL Maintenance

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The UK’s MSF signal broadcast from Anthorn, Cumbria and utilised by UK NTP server users is be turned off for a four hour period on 11 June for scheduled maintenance. The MSF 60 kHz time and frequency standard will be off between 10.00 and 14:00 BST (9:00 – 13:00 UTC).

Users of NTP time servers that utilise the MSF signal should be aware of the outage but shouldn’t panic. Most network time servers that use the Anthorn system should still function adequately and the lack of a timing signal for four hours should not create any synchronisation problems or clock drift.

However, any testing of time servers that utilise MSF should be conducted before or after the scheduled outage. Further information is available from NPL.

Any network time server users that require ultra-precise precision or are feel temporary loss of this signal could cause repercussions in their time synchronisation should seriously consider utilising the GPS signal as an additional means of receiving a time signal.

GPS is available literally anywhere on the planet (as long as there is a good clear view of the sky) and is never down due to outages.

For further information on GPS NTP server can be found here.