Diagram of CHU Leap-Second Recording and "Atomic" Clock

From: Richard Langley <lang_at_unb.ca>
Date: Wed, 4 Jan 2006 12:04:46 -0400 (AST)

I recorded the audio of the 3330 kHz signal of the National Research Council
of Canada's time signal station CHU from a few minutes before, until a couple
of minutes after, midnight UTC on New Years' Eve. A PDF of the annotated
sampled-signal time series between 23:59:00 and 0:00:01 can be found here:
<http://gge.unb.ca/Resources/CHU.31Dec05.leapsecond.pdf>. The leap second was
correctly inserted. However, starting one minute after UTC midnight, DUT1
became +0.4 seconds rather than +0.3 seconds as prescribed by IERS. The +0.4
second value continued to be transmitted until some time on 3 January 2006.
According to an NRC staff member, the problem arose because the IERS Bulletin
D announcing the +0.3 second value was not sent out until 28 December and
was not seen until people returned to work on 3 January after the holidays.
This problem seems to have occurred with some other time signal stations too.

Simultaneous with the audio recording of CHU, I videotaped the display of a
SkyScan "atomic" clock, model 31981, marketed by Equity Time U.S.A., which
receives the WWVB signal. It did not account for the leap second at UTC
midnight. Likely it continued that way until it next tried to receive the WWVB

 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/
Received on Wed Jan 04 2006 - 08:05:54 PST

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