The MSF-60 atomic clock synchronized radio time transmission is considered by many NTP time server and PC computer systems are used for precise synchronization of the time made available to applications. This article describes how the MSF-60 time signal of NTP time servers and computer systems is decoded to be an accurate timing reference.
The MSF-60 Time Transmitter
The MSF-60 time signal is a long-wave radio clock signal broadcast from Rugby, Warwickshire, England. RadioRadio signal from BT Engineering Services on behalf of the National Physical Laboratory (NPL) maintained. From 1 April 2007, the MSF-60 transmission is made Anthorn, Cumbria, transfer with atomic clock and time code equipment by VT Communications.
When decoded, provides the MSF-60 time signal is a very accurate timing reference for NTP server, watches and other computer timing equipment.
Signal Coverage
The MSF-60 radio clock signal broadcastbe received in a satisfactory manner throughout the British Isles and much of the north-west Europe. Reception problems can typically due to local environmental conditions. The radio signal can be of metal structures or frames that are blocked as a Faraday cage effect. In addition, signal reception can be difficult in the vicinity of electrical equipment noise. Radio receivers are also above the ground.
The MSF-60 Time Code
Time and will be sent to continually updated information, repeatedper minute. The data will be transferred to off-modulated carrier, pulse-width encoded data signal. Each record is transmitted as a bit-pulse per second. The data transmitted from the current time and date, leap second indicator, daylight savings indicator and parity bits.
A 500-millisecond carrier off period is the beginning of each minute. The other 59 seconds consisting of 100 to 300 milliseconds carrier and at least 700 milliseconds of carrieron.
Transmitted Data.
The time and date information can be found in BCD (Binary Coded Decimal) format and is presented coded as follows: 1-16 bits are used to convey information about the difference between atomic and astronomical time (DUT1).
The remaining bits, 17 to 59, the date and time include information about the current minutes as follows: bits 17-24, BCD encoded year (00-99), bits 25-29, BCD months of the year (01-12); bits 30-35, BCD-coded day of the month (01-31), bits 36-38, BCDencodes day of the week (0-6,) 0 = Sunday, bits 39-44, BCD-coded hour (00-23), bits 45-51, BCD-coded minutes (00-59).
During British Summer Time, bit 58 to '1 '. Even in the 60 minutes prior to a change in British Summer Time, bit 53 to '1 '.
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