Time from NPL (MSF)
History
History
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[thumb\|Received, at Lesvos Island, during the transfer from Rugby to Anthorn](/wiki/File:Rugby_Anthorn_MSF.jpg "Rugby Anthorn MSF.jpg")
A radio station at Rugby was first operated by the [Post Office](/wiki/General_Post_Office "General Post Office") from 1926, with the call\-sign GBR. From 19 December 1927, it broadcast a 15\.8 kHz time signal from the [Royal Observatory](/wiki/Royal_Observatory%2C_Greenwich "Royal Observatory, Greenwich") which could be received worldwide. It consisted of 306 pulses in the five minutes up to and including 10:00 and 18:00 [GMT](/wiki/Greenwich_Mean_Time "Greenwich Mean Time"), with a longer pulse at the start of each minute. [Frequency\-shift keying](/wiki/Frequency-shift_keying "Frequency-shift keying") was added in 1967, making the signal harder to use as a frequency reference. The time signals, preceded by the callsign "GBR GBR TIME" in [Morse code](/wiki/Morse_code "Morse code"), were transmitted during the 5 minutes preceding 03:00, 09:00, 15:00 and 21:00\. Transmitter GBZ on 19\.6 kHz was used as a reserve, when GBR was off\-air for maintenance. Eventually, time signals from GBR were terminated in November 1986 and it is no longer used as a frequency reference.

The MSF signals started in 1950, following the transmission pattern [described below](/wiki/%23Protocol "#Protocol"). They were originally intended to provide frequency references at 2\.5, 5 and 10 MHz, originally only occasionally during the day. At first, there were announcements every fifteen minutes, beginning with the Morse code representation of "MSF MSF MSF" (MSF is "\-\- ··· ··\-·" in Morse code), followed by speech "This is MSF, Rugby, England, transmitting ...". From May 1953, the signal was broadcast 24 hours a day, but with regular five\-minute stoppages to allow the reception of other signals. The 60 kHz signal finally became an uninterrupted 24\-hour service in 1966, and the frequency references were discontinued in February 1988\.

On 27 February 2007 the NPL started tests of the new time signal transmissions from [Anthorn](/wiki/Anthorn_Radio_Station "Anthorn Radio Station"). The Anthorn station was operated by [VT Communications](/wiki/VT_Communications "VT Communications") from its opening in 2007 until 2010, when it was acquired by [Babcock International](/wiki/Babcock_International "Babcock International"). General and technical information, advice on reception problems, and up\-to\-date information on signal outages and scheduled maintenance

The formal inauguration of the relocated facility took place on 1 April 2007, when the name of the service became "The Time from NPL" and the signal from Rugby was permanently switched off. The change in location and consequent change in signal strength can make some equipment designed to use the MSF signal fail to continue doing so. This is found more in domestic equipment not designed for optimum sensitivity and positioned haphazardly.
Currently, the signal from Anthorn is still useable, in the location of the Mediterranean, although it is weaker than Rugby.


When was frequency-shift keying added to the time signal?