Using MSF as a Timing Reference for NTP Servers

By: Richard N Williams
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Atomicclocks are incredibly expensive and generally they are normally only to befound in large scale physics laboratories such as MIT (Massachusetts Instituteof Technology), NIST (National Institute of Standards and Technology (Colorado)or the National Physical Laboratory in the UK.

Fortunately, many national laboratories broadcast the UTC(Coordinated Universal Time) time from their atomic clocks via a radio transmission.

In the UK the national timing broadcast is called MSF and isbroadcast by NPL (National Physical Laboratory) in Cumbria. The MSF broadcastis used by throughout the UK and parts of Europe to synchronise consumerelectronic products like wall clocks, clock radios, and wristwatches. Inaddition, MSF is used for high-level applications such as network timesynchronisation utilising NTP.

The time code contains the year, day of year, hour, minute,second, and flags that indicate the status of Daylight Saving Time, leap years,and leap seconds.

MSF operates on a frequency of 60 kHz and carries a time anddate code that can be received and decoded by a wide range of readily availableradio-controlled clocks and provides a received accuracy should be less than 10milliseconds (1/100 of a second).

While many NTP servers now use GPS to receive a timingreference, the advantage of using a radio transmission is that a signal can bereceived indoors (a GPS antenna needs a good view of the sky).

However, the radio signal has a finite range and can beblocked by skyscrapers, mountains and dense conurbations. A radio based NTP server usually consists of arack-mountable time server, and an antenna, consisting of a ferrite bar insidea plastic enclosure, which receives the radio time and frequency broadcast. Theantenna should always be mounted horizontally at a right angle toward thetransmission for optimum signal strength.

Similarnational timing transmissions are broadcast from other countries in the US thesignal is referred to as WWVB and is broadcast by the NIST (National Institutefor Standards and Technology) in Fort Collins, Colorado, other systems arebroadcast in Frankfurt, Germany (DCF-77)Feature Articles, Japan (JJY) and France (TDF).

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