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Automated Computer Time Service (ACTS)
The Automated Computer Time Service (ACTS) is run by the National Institute of Standards and Technology (NIST) in Boulder, Colorado.
ACTS allows computer users with modems to synchronize their clocks by telephone. The phone number for ACTS is (303)
The full time code is transmitted every second and contains more information than the 300 baud time code, which is transmitted every 2 seconds. The full time code looks like this:
JJJJJ YRMODA HH:MM:SS TT L DUT1 msADV UTC(NIST) OTM
where
JJJJJ | = | the Modified Julian Date (MJD). The MJD is the |
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| last five digits of the Julian Date, which is the |
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| number of days since January 1, 4713 B.C. To get |
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| the Julian Date, add 2.4 million to the MJD. |
YRMODA | = | the date, showing the last two digits of the year, the |
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| month, and the current day of month. |
HH:MM:SS | = | the time in hours, minutes, and seconds. The time is |
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| always sent as Coordinated Universal Time (UTC). |
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| An offset needs to be applied to UTC to obtain local |
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| time. For example, Mountain Time in the U. S. is |
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| 7 hours behind UTC during Standard Time, and |
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| 6 hours behind UTC during Daylight Saving Time. |
TT | = | a two digit code (00 to 99) that indicates whether the |
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| United States is on Standard Time (ST) or Daylight |
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| Saving Time (DST). It also indicates when ST or |
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| DST is approaching. This code is set to 00 when ST |
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| is in effect, or to 50 when DST is in effect. During |
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| the month in which the time change actually occurs, |
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| this number decrements every day until the change |
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| occurs. For example, during the month of October, |
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| the U.S. changes from DST to ST. On October 1, |
TimeVault User’s Manual |
