Thank you Tom, I have a very primitive frequency comparator built some
thirty years ego, which compares the line frequency to WWVb 60kHz, since
the new format for WWVb was introduced it does not work so great any
more, but it is still good enough to see if the line frequency is to
fare off. Basically it is just counting the periods of the line
frequency and the counter's gate time could be set for hour/day/
week/month and the reset time is derived from the WWVb datum. I have
seen also some daily deviations of the 60Hz similar what your picture
shows, but interestingly the long time average -- one whole year -- up
to now is correct
73
KJ6UHN
Alex
On 8/12/2016 11:03 AM, Tom Van Baak wrote:
before you buy AC line disciplined clock read that
Alex,
That old article from 2011 is misleading. It correctly describes what was being
/proposed/, but it turns out NERC chose not to implement what the article
(fears) talks about. There are lots of time-nuts postings about this in the
2011 archives if you want to read more. Or google for TEC (time error
correction).
So your 60 Hz timekeeping is probably fine and still loosely locked to UTC. Several of
us time nuts continuously monitor mains frequency & phase for fun. It's an
interesting and low-cost entry into the world of time & frequency measurement,
long-term data logging, data analysis, Allan deviation, etc.
Here's a quick plot showing the last 2 months (US western grid). Someone else
(Hal?) can double check it.
http://leapsecond.com/pages/mains/mains-june-july-2016.gif
/tvb
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