[time-nuts] Weird TEC data
Hal Murray
hmurray at megapathdsl.net
Sun Aug 7 00:13:49 UTC 2011
newell at cei.net said:
> The general shape and bumps in the plots track nicely, but I'm wondering
> why there's so many cycles difference after 36 hours.
How are you collecting the data? What's the time between samples?
One possibility is that one system is picking up extra clock ticks. If your
data is dense enough, that should be pretty obvious if you zoom in on the
graph.
Here is an example:
http://www.megapathdsl.net/~hmurray/time-nuts/60Hz/60Hz-g3.png
That's sampling every 10 seconds.
Glitches like that are easy to spot if you plot the frequency. It's the
difference in counts divided by the difference in times between a pair of
samples. At 10 second sampling rate, you get 600 counts per sample. 601
counts turns into 60.1 Hz. That 0.1 Hz is well above the noise. (at least
with my setup)
--
These are my opinions, not necessarily my employer's. I hate spam.
More information about the time-nuts
mailing list