The MSF radio signal is a dedicated standard-frequency and time broadcast that provides an accurate and reliable source of UK civil time. It is available 24 hours a day across the whole of the UK and beyond. The signal operates on a frequency of 60 kHz and carries a time and date code that can be received and decoded by a wide range of readily-available radio-controlled clocks.
The MSF signal is transmitted from Anthorn Radio Station in Cumbria by Babcock International, under contract to NPL. The signal covers the whole of the UK, and can also be received throughout most of northern and western Europe. It is monitored against the national time scale UTC(NPL) and corrected when necessary, ensuring that the transmitted time is always correct.
The signal is occasionally taken off-air to allow maintenance work on the masts and antennas at Anthorn Radio Station to be carried out in safety. A radio-controlled clock will not be able to pick up the MSF signal during these periods, so may drift off from the correct time.
The duration of each outage period will be kept to a minimum, and the signal may be back on-air prior to the times given above.
In addition to these dates, the signal is likely to be taken off-air for a two-week period during summer each year, though the transmission will be restored overnight whenever possible. The dates of this longer outage will be announced on this page and by emailed notices to registered users as soon as they are known.
The dates and times of the 2026 maintenance periods are as follows:
04 to 05 February 2026 from 09:00 GMT to 18:00 GMT (UTC) — Minimal service impact
12 March 2026 from 10:00 to 14:00 GMT (UTC) — Full shutdown
29 June to 17 July 2026 from 08:00 to 18:00 BST (UTC + 1) — Full shutdown
10 September 2026 from 10:00 to 14:00 BST (UTC + 1) — Full shutdown
10 December 2026 from 10:00 to 14:00 GMT (UTC) — Full shutdown
If the weather is unsuitable for work to be carried out, then the service will not be turned off.
The signal is likely to be taken off air for longer periods over two-week maintenance windows during the summer each year, though the transmission will be restored overnight whenever possible.
The dates of planned maintenance will be announced on this page and by emailed notices to registered users as soon as they are known.
The main causes of reception problems are local interference from electrical equipment and a reduced local signal due to screening by nearby metalwork, for example in a steel-framed building. If your radio-controlled clock is having difficulty receiving the MSF signal, please first read through the information in the 'Common clock problems' document.
Common MSF signal reception problems
Find out more detailed technical information about the MSF time code, signal strength and carrier frequency accuracy.