I used a U.S. "black friday" discount to buy a copy of the 2nd edition of Dave
Mills' "Computer Network Time Synchronization: The Network Time Protocol on
Earth and in Space". I've had the library's copy of the 1st edition on my
shelf for a long time, renewing as needed several times over. The new book is
much thicker than the previous version and includes additional material. In
particular I want to work through the implications of time transfer techniques
for space missions.
It would be nice if the ITU deliberations would feature discussions pivoting on
such substantive references. From the last few messages, it sounds rather that
delegates will wave their paddles and that will be that (for a proposal many
may not have even read).
Quoting from Mills' chapter on "Metrology and Chronometry of the NTP
Timescale", p. 235:
"So, why bother with UTC in the first place? It would be much simpler
to adopt TAI and avoid leap seconds altogether, as in fact the case with the
POSIX specification. However, there is no escaping that synchronization with
conventional human activities requires UTC or in case of birth and death
certificates UT1. There are many facets of this argument, some based on
practical matters like a reliable source of historic and anticipated leap
second epochs and suitable provisions in the computer time management software
and some based on anecdotal sensibilities. In the end, it seems prudent that
the computer clock runs in UTC with leap insertions as described."
Now, I can already hear the leapsecs replies :-) Before folks get started,
please consider that the ITU is not even considering the option that Mills is
outlining. Without rehashing a dozen years of discussions, the fact is simply
that we here on this list are far more willing to entertain creative options
than what is contained in the embargoed ITU proposal.
We deserve a better process and more attention to substantive engineering
details.
Rob Seaman
National Optical Astronomy Observatory
--
PS - independently of the leap second issue, I strongly recommend either
edition of Mills' NTP book. Do folks here have other "timely" book
recommendations for Holiday reading? I will also recommend McCarthy &
Seidelmann's "Time: from Earth Rotation to Atomic Physics".
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