In message: <7a21eaec-bb0a-4966-a8db-86b084df0...@batten.eu.org> Ian Batten <i...@batten.eu.org> writes: : > 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.
I think that this is why the leap second proposals say they won't disseminate DUT1 anymore. All they really mean by that, I think, is that we'll measure it, we'll pubish it, but the time broadcasts will reset it to '0' and users should note that it isn't available that way anymore. I lump all the gear that (a) needs to know about it and (b) does something with it in the same boat. There is a danger here, however if the (b) is display it to the user who then doesn't know that something is amiss and believes '0'. Warner _______________________________________________ LEAPSECS mailing list LEAPSECS@leapsecond.com http://six.pairlist.net/mailman/listinfo/leapsecs