Getting an accurate source of time for computer networks and other technologies is increasingly becoming more important. As technologies advance and global communications mean that we are just as liable to communicate with technology across the other side of the planet as we are at home.
The need for accurate time is therefore essential if you wish to prevent time sensitive applications on your network failing or to avoid debugging problems – not too mention keeping your system secure.
NTP time servers (Network Time Protocol) are common devices that many computer networks use to provide a source of accurate time as NTP is able to ensure entire networks are synchronised to just a few milliseconds to the time reference.
The time reference that NTP servers use can come from several locations:
- The internet
- GPS satellite
- And National Physical Laboratories
In the UK, the National Physical Laboratory (NPL) produce a time signal that can be received by radio referenced NTP time servers. This used to be broadcast from rugby in central England but in recent years the transmission has been moved to Cumbria.
The Cumbrian signal, known as MSF, is broadcast from Anthorn with a signal strength of 100 microvolts per metre at a distance of 1000 km. This should mean that the signal is available everywhere in the UK; however, this is not strictly the case as many MSF clocks and time servers can run into trouble when first trying to receive this atomic clock generated signal.
However, a simple checklist should ensure that no matter what your location you should be able to receive a signal to your MSF clock or NTP time server:
- Check the power. Perhaps the most common problem ensure the battery is inserted and if the clock uses both mains power and a battery, remember to switch the mains power on. It can take quite a few minutes for the clock to pick up the MSF signal, so be patient.
- Try rotating the clock or time server. As the MSF signal is long wave the antenna needs to be perpendicular to the signal for best reception.
- If all else fails move the clock or time server to a different location. The signal can be blocked by local interference from electrical and mechanical devices.
* Note the MSF signal is down for scheduled maintenence on Tuesday 9 September 2010 from 10:00 BST to 14:00 BST