Hi Ed,
Welcome to the group and thanks for sharing that 60 Hz mains
project. Nice use of a 5316B and Prologix adapter to collect the
frequency data and Python and JavaScript to display live plots.
Is there a URL for the raw data files (the YYYMMMDDHH.DAT
files mentioned in code_2.txt)? I'd like to compare yours with the
Western Power Grid that data I collect here in Seattle.
On your gauge/hertz.html page, how do you compute the "grid
time error" value and have you compared it with a kitchen wall
clock? What date/time did you reset the value to zero?
I collect my data slightly differently and so it will be interesting
to see how making measurements with a periodic frequency
counter compare with direct timing measurements of phase.
I agree with your comment about "7 seconds a day". See also:
http://www.leapsecond.com/pages/mains/
Thanks,
/tvb
----- Original Message -----
From: "Ed Mersich" <[email protected]>
To: <[email protected]>
Sent: Sunday, April 01, 2012 3:18 PM
Subject: [time-nuts] 60Hz More or Less
My Heathkit, and other AC clocks have been broken for months now. I started
a project to figure out how bad it was. It's getting interesting as I am
approaching my goal of coding a software emulation of an AC line clock.
During the process I developed a couple of web pages to help me understand
the problem better. Frequency meter:
http://wa6rzw.homelinux.net/addon/grid/gauge/hertz.html
Grid history graph:
http://wa6rzw.homelinux.net/addon/grid/graph/wgraph_1.html
The meter requires a real HTML5 browser, anything but MSIE.
When I started this my goal was to provide an external reference source to
the Heathkit CG-1005, so that it will keep correct time. Since I began I
have considered a number of hardware solutions to correct or modify the
Heathkit. I think I am dragging my feet because there are no replacement
clock chips (in case of disaster,) to be found for this model. At the moment
I am thinking about modifying a DC-AC inverter and syncing it to an audio
oscillator, (don't laugh, my Heathkit 30 year old audio generator is way
better, more stable, than the grid).
73, Ed - WA6RZW
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