[LEAPSECS] h2g2

Ian Batten igb at batten.eu.org
Fri Sep 3 14:34:59 EDT 2010



> do we

> have enough of a community of |DUT1| < 1s to justify the costs to the

> rest of the world, or is it time that this crowd shoulder the costs of

> the raw data they need?


Of course, one issue is that it's not a matter of |DUT1|<1s, but
having DUT1 at all. The formats by which DUT1 is propagated in time
signals deeply assume <1, so if it became >1 it couldn't be propagated
in those signals. Which means that any and all equipment that
consumes it is instantly broken, as it can't recover UT1. Even if the
format could accommodate >1, of course, one assumes that almost all
sane implementations would sanity check the value of DUT1 to confirm
it's <1, so would reject the larger value anyway.

You could modify the format, but you'd have to do so in a way which
didn't then break all the equipment that wants UTC but pokes around in
the extra data to recover the date, or the summer time indicator, or
whatever. And it would involve replacing all the UT1 equipment anyway.

I don't know, and I suspect the ITU don't either, how much (if,
indeed, there is any) equipment is currently consuming the DUT1
portion of the national time standards, and why.

ian



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