[LEAPSECS] New time scale name

M. Warner Losh imp at bsdimp.com
Fri Aug 13 10:31:13 EDT 2010

In message: <20100813090057.15429.qmail at protonet.co.za>
p at 2038bug.com writes:

: From all I've heard it seems best to make UTC and UT1 identical,

: and to start broadcasting UT1 over the radio and NTP networks.

Best? This isn't an 'upgrade' at all, but rather returns to the
1960's practice of having "rubber" seconds. The UT1 second doesn't
tick at a constant rate, so you have to constantly update the notion
of the second.

: And drop further leap seconds of course. I have tried, but can't

: find a system that would break because of this.

All the stratum 0 NTP servers would break. The vast majority of them
are based on GPS, which is based on UTC and cannot be based on UT1
since that would destroy the accuracy of GPS. If you mandate UT1 be
broadcast by NTP servers, then you'd need to find a way to get highly
accurate (to 1ms) DUT1 data. This information isn't available in real
time (although good estimates are). This information also isn't
broadcast as part of GPS' almanac. There's a large number of NTP
based on GPS networks that aren't Internet connected, so that would
break them.

: 2nd option is to keep leap seconds but upgrade the NTP and radio

: protocols to give more warning - not 10 years warning, just *more*

: warning.

This is the sensible option that many people have been advocating.
However, to do this right, you'd have to put more funding into
modeling the earth, and also accept that you might, for periods of
time, have > .9s divergence between UT1 and UTC. In order to do that,
you have to deal with how to broadcast that information. There are
sources of this data on the Internet, but the data format doesn't
allow for > 1s representation of |DUT1|.

: 3rd (worst) option is to just stop announcing leap seconds.

This also suffers from the same problems as #2.


: -paul

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