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

David L. Mills mills at udel.edu
Mon Nov 3 18:37:34 UTC 2003


Tom Van Baak wrote:
> 
> 3) You also know months (or even years) ahead
> of time what the DUT1 sign is.
> So 1+2+3 allows you to know well in advance
> when and what type of leap second it will be.
> 
> Thus there's no requirement to be following the
> timecode during the exact minute before the leap
> second. Which is a good thing because it is likely
> you won't have good reception anyway.

I didn't mean to imply required reception during the minute before the
leap. In fact, the WWV/H reference clock driver makes no such
assumption, just that the leap bit (and presumably DUT1) have been
previously received and available at the leap epoch. 
...
> > the three-bit DUT1 magnitude in WWV/WWVH.
> 
> Is not bit 50 the DUT1 sign for WWV/WWVH? See:
> 
> http://www.boulder.nist.gov/timefreq/stations/wwvtimecode.htm

As I said previously, the three-bit DUT1 magnitude field can encode only
0-7 deciseconds of either sign. So far as I remember, the DUT1 has never
exceeded +-7 deciseconds before a leap is taken.

Dave



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