[ntp:questions] Re: GMT: UT1 vs UTC

David L. Mills mills at udel.edu
Mon Nov 3 05:38:30 UTC 2003


The typo should have been WWV/WWVH, not WWV/WWVB. WWVB does have a leap
warning (bit 56), a four-bit DUT1 magnitude (bits 40-43) and three (!)
DUT1 sign (bits 36-38). The WWV/WWVH timecode has a leap warning (bit
3), a three-bit DUT1 magnitude (bits 56-58) and DUT1 sign (bit 50).

However, you raise an interesting idea. The on-time epoch is the
beginning of the minute that the timecode is actually sent. From the
leap warning you know the epoch that a leap must be made and in the
previous minute the DUT1 sign. From this you can predict the DUT1 after
the leap and thus the leap correction. Clever. I'm still worried about
the three-bit DUT1 magnitude in WWV/WWVH.

Notwithstanding the above, I was told by NIST staff that the NIST
timecode generators do not implement a negative step. I have no
information about other stations.

See http://www.boulder.nist.gov/timefreq/stations/wwvbtimecode.htm.


Tom Van Baak wrote:
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