[LEAPSECS] Ghosts of Leap-seconds past and future

Richard B. Langley lang at unb.ca
Tue Dec 28 07:56:15 EST 2010

I have been asked to remind list members of the presentation by Ron
Beard, the chairman of ITU-R Working Party 7A, at ION GNSS 2010. The
PowerPoint slides can be downloaded from here:

Here are the conclusions, summary, and actions from the presentation:


Major scientific and GNSS organizations have not taken issue with the subject
There has been ample opportunity and encouragement to contribute

The lack of response has been interpreted as having no concern and
thus no established opinion

Little information on quantitative costs has been provided

The few estimates offered seem to be guesses at best

Few observers noted there are costs associated with maintaining the
status quo that may or may not be mitigated

Most experts in time metrology agree on the necessity for the change
and offer technical support

The Consultative Committee on Time and Frequency strongly recommends
proceeding with a decision so enough time is available for any
necessary software and systems modifications


Documents demonstrate a clear misunderstanding of the definitions and
applications of time scales and system times for internal
o Indications that users have the choice between UTC, TAI, UT1, GPS
Time for their applications is incorrect
o UTC is the only international standard time scale, represented by
local approximations in time laboratories, that should be used for
worldwide time coordination and measurement traceability
o TAI is not an option for applications needing a continuous reference
as it has no means of dissemination, and it is not physically
represented by clocks
o GPS time is not a reference time scale, it is an internal time for
GPS system synchronization, as other GNSS system times would be
o A variety of continuous internal system time scales have
proliferated to provide a solution to the problems associated with
discontinuities in UTC

The existence of multiple time scales creates potential problems in
operational use as well as conceptual confusion on the proper
definition and roles of time references


Working Party 7A exhausted technical considerations and studies

Consensus not reached on other than technical grounds

Submitted to Study Group 7 for resolution

So far, I have not seen any reports from Study Group 7 subsequent

-- Richard Langley

Quoting Rob Seaman <seaman at noao.edu>:

> God bless us, every one!


> On Dec 26, 2010, at 8:40 PM, Richard B. Langley wrote:


>> Quoting Rob Seaman <seaman at noao.edu>:


>>> The ITU, rather, have monomaniacally pursued one-and-only-one

>>> NON-solution for a decade, and have assiduously avoided

>>> characterizing the problem they claim to seek to solve.


>>> "Slander those who tell it ye! Admit it for your factious

>>> purposes, and make it worse! And bide the end!"


>>> So yes - I will continue to rattle my chains.


>> Dare we hope for a Scrooge-like transformation of the ITU? ;-)


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Richard B. Langley E-mail: lang at unb.ca
Geodetic Research Laboratory Web: http://www.unb.ca/GGE/
Dept. of Geodesy and Geomatics Engineering Phone: +1 506 453-5142
University of New Brunswick Fax: +1 506 453-4943
Fredericton, N.B., Canada E3B 5A3
Fredericton? Where's that? See: http://www.city.fredericton.nb.ca/

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