[LEAPSECS] a less intrusive procedure

John Sauter John_Sauter at systemeyescomputerstore.com
Thu Jul 21 14:23:44 EDT 2016

On Thu, 2016-07-21 at 10:27 -0700, Tom Van Baak wrote:
> Time to mention this again...
> If we adopted the LSEM (Leap Second Every Month) model then none of
> this would be a problem. The idea is not to decide *if* there will be
> leap second, but to force every month to have a leap second. The IERS
> decision is then what the *sign* of the leap second should be this
> month.
> Note this would keep |DUT1| < 1 s as now. UT1 would stay in sync with
> UTC, not so much by rare steps but by dithering. There would be no
> change to UTC or timing infrastructure because the definition of UTC
> already allows for positive or negative leap seconds in any given
> month.
> Every UTC-aware device would 1) know how to reliably insert or delete
> a leap second, because bugs would be found by developers within a
> month or two, not by end-users years or decades in the future, and 2)
> every UTC-aware device would have an often tested direct or indirect
> path to IERS to know what the sign of the leap second will be for the
> current month.
> The leap second would then become a normal part of UTC, a regular
> monthly event, instead of a rare, newsworthy exception. None of the
> weird bugs we continue to see year after year in leap second handling
> by NTP and OS's and GPS receiver firmware would occur.
> Historical leap second tables would consist of little more than 12
> bits per year.
> Moreover, in the next decade or two or three, if we slide into an era
> where average earth rotation slows from 86400.1 to 86400.0 to 86399.9
> seconds a day, there will be zero impact if LSEM is already in place.
> /tvb

I suggest a less intrusive procedure which would have some of the same

Every serious project includes a test procedure to verify that the
product is working.  That test procedure involves running the product
within a test harness which feeds it inputs and records its outputs.
 Within that test harness, pretend that every minute ends with either a
positive or negative leap second.  Bugs in the handling of leap seconds
will thus be found very quickly.

This procedure can be implemented by a product developer without
getting co-operation from the IERS or any other external entity.
 However, it does not address the problem of timely access to the IERS.
    John Sauter (John_Sauter at systemeyescomputerstore.com)
PGP fingerprint E24A D25B E5FE 4914 A603  49EC 7030 3EA1 9A0B 511E
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