Tom Van Baak wrote:
But there have been real bugs due to leap indicators remaining set too
long, leading to bogus leaps at the end of July. So in practice there is
less risk in allowing leaps only in June and December.
Those real bugs are better fixed at their source than worked around in this
manner. Ok, easy to say and hard to do, I know.
Perhaps leap indicators should not be booleans but small wrapping integers. For
example GPS makes use the low order 8 bits of the week number for almanac
version checks. Perhaps the same could be done for leaps, especially if they
are encoded as a TAI offset integer instead of +/- yes/no booleans.
The truncated week numbers are a good source for potential errors.
Especially the 8 bit WNls week number in the GPS UTC parameter set has
to be untruncated to 10 or more bits by the firmware to compute the real
point in time for a leap second.
If the current week number is off by more than +-127 then this is
ambiguous. This has rolled over several time in the period where no leap
second had been scheduled for 7 years, and all the time the 8 bit week
number of the last recent leap second was broadcast.
Martin
--
Martin Burnicki
Senior Software Engineer
MEINBERG Funkuhren GmbH & Co. KG
Email: [email protected]
Phone: +49 (0)5281 9309-14
Fax: +49 (0)5281 9309-30
Lange Wand 9, 31812 Bad Pyrmont, Germany
Amtsgericht Hannover 17HRA 100322
Geschäftsführer/Managing Directors: Günter Meinberg, Werner Meinberg,
Andre Hartmann, Heiko Gerstung
Web: http://www.meinberg.de
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