[mdmars_members] //MARS R/ FYI --->> CHU TIME STATION CHANGES FREQ

  • From: J Sears <aat3ok@xxxxxxxxx>
  • To: AIG-2 <mdmars_members@xxxxxxxxxxxxx>
  • Date: Fri, 19 Dec 2008 13:03:33 -0800 (PST)

 from QRZ.com ARRL Letter # 27

After 70 years of broadcasting Canada's official time, the National
Research Council's shortwave station CHU
ml> will move the transmission frequency for the 7335 kHz transmitter to
7850 kHz. The change goes into effect at 0000 UTC on January 1, 2009.

Broadcasting 24 hours a day, CHU is a part of NRC's system for
disseminating official time throughout Canada. Listeners hear tones to
mark the seconds, a voice to announce the time in French and English and
digital data to set computers. The atomic clocks at CHU are part of the
ensemble of clocks in the time and frequency research laboratories at
the National Research Council Canada in Ottawa. The NRC clocks are used
in conjunction with clocks in the time laboratories of other countries
to construct the internationally accepted scale of time, UTC
(Coordinated Universal Time). Time transmissions on 3330 and 14670 kHz
are not affected and will continue as before.

In April 2007, the ITU reallocated the 7300-7350 kHz band from the fixed
service to the broadcasting service. Since then, the NRC said there has
been a lot of interference on the 7335 kHz frequency from many
information broadcasters around the world. "CHU listeners in Canada and
around the world who have for so long considered the 7335 kHz frequency
exclusively for time signals, are very vocal about this interference,"
said Raymond Pelletier, Technical Officer at the NRC-Institute for
National Measurement Standards, who oversees the CHU facility. "We have
heard from Amateur Radio operators, watchmakers, astronomers and
navigators who use the tones and voice signals. We also received
comments from those who use the carrier as a calibration source at a
distance for their equipment."

Pelletier noted that a leap second
<http://inms-ienm.nrc-cnrc.gc.ca/faq_time_e.html> will be added at the
end of December 2008; this will be indicated in the digital code until
the time of the leap second. DUT1 will go from -0.6 to +0.4 seconds and
will be indicated by double tones near the start of the minute and in
the broadcast code


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