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Article Title: Decoding The MSF-60 UK Radio Time Broadcast
Author: Dave Evans
Category: Science, Satellite Radio, Technology
Word Count: 497
Keywords: time server, radio time, msf time, ntp server, network time server
Author's Email Address: [email protected]
Article Source: http://www.articlemarketer.com
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The MSF time and frequency broadcast is a radio time signal transmitted from 
Anthorn, Cumbria in the UK. The signal can be used as an accurate and reliable 
source of time derived from atomic clocks at the UK National Physics 
Laboratory. The effective radiated power of the transmitter is 15kW, providing 
a transmission range of approximately 1000 km. The signal can be received 
throughout the UK and much of northwestern Europe. It is often used by 
synchronised clocks and watches and network time servers. This article 
describes how the MSF-60 time broadcast is transmitted and can be decoded by 
computer systems to provide an accurate timing reference.

The MSF radio signal is maintained by VT communications under contract from the 
National Physics Laboratory (NPL). The broadcast is monitored by NPL and 
adjusted as necessary to maintain accuracy. When decoded, the MSF-60 time 
signal provides a highly accurate and reliable timing reference for clocks, NTP 
Time Servers and other computer timing equipment.

Signal reception problems can generally be attributed to local environmental 
conditions. The radio signal can be blocked or weakened by metal structures or 
frames, which effectively act as a Faraday cage. Additionally, signal reception 
can be difficult near electrically noisy equipment. Radio receivers should also 
be located above ground, reception underground or in basements can prove 
difficult. The transmission is taken off-air once or twice a year for short 
durations for maintenance work on the transmitter. A list of scheduled outages 
is available from the NPL website.

Time and date information is transmitted continuously, repeated each minute. 
The data is transmitted as on-off carrier modulated, pulse-width coded data 
signal. Each data bit is transmitted as a pulse, one per second. The data 
transmitted consists of the current time and date, leap second indicator, 
daylight saving time indicator and parity bits.

A 500-millisecond carrier off period indicates the start of each minute. The 
other 59 seconds consist of between 100 and 300 milliseconds carrier off and at 
least 700 milliseconds of carrier on. Time and date information is presented in 
BCD (Binary Coded Decimal) format and is encoded as follows: bits 1-16 are used 
to convey information about the difference between atomic and astronomical time 
(DUT1).

The remaining bits, 17 to 59, contain date and time information about the 
current minute as follows: bits 17-24, BCD encoded year (00-99); bits 25-29, 
BCD month of year (01-12); bits 30-35, BCD encoded day of month (01-31); bits 
36-38, BCD encoded day of week (0-6, 0 = Sunday); bits 39-44, BCD encoded hour 
(00-23); bits 45-51, BCD encoded minute (00-59).

During British Summer Time, bit 58 is set to '1'. Also in the 60 minutes 
leading up to a change in British Summer Time, bit 53 is set to '1'.

To summarise, the MSF radio time and frequency broadcast provides a reliable 
and accurate source of time for radio-controlled clocks, computer network 
timing equipment and many other applications. It can be received throughout the 
UK, and with relatively low-cost radio receivers provides a precise, traceable 
time reference.

David Evans is a technical author in the field of time and frequency 
applications. Find out more about NTP servers and network time servers at:
http://www.timetools.co.uk/
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