[time-nuts] More 60 Hz graphs

[Hal Murray]

Was: Subject: Re: [time-nuts] 60hz west coast electric grid gone berserk

albertson.chris at gmail.com said:
> What? Lets assume 80 characters per line at 60Hz that word to a whopping
> 4800 bytes per second.  For a modern desktop computer moving even a million
> bytes per second is trivial.  Even 10 times that much is easy.  In the 1/
> 60th second between cycles a simple desktop computer can execute well over a
> hundred million instructions. 

Thanks for the poke.

The obvious thing to do was try it.  So I collected a half-hour of data.  
Things are more interesting when you have data for every cycle (as compared 
to every 10 seconds).

Here is the offset from 60 Hz:
  http://www.megapathdsl.net/~hmurray/time-nuts/ppstest/60Hz.png

Here is the frequency:
  http://www.megapathdsl.net/~hmurray/time-nuts/ppstest/60Hz-freq.png
I don't know where the wobbles are coming from.  They might be in my 
collection setup.

Here is the step-size between samples:
  http://www.megapathdsl.net/~hmurray/time-nuts/ppstest/60Hz-step.png
The row at 30+ ms is where the collection system couldn't keep up and missed 
a sample.
The top row is where it missed 3 samples.

This is zooming in, ignoring the missed-sample cases:
  http://www.megapathdsl.net/~hmurray/time-nuts/ppstest/60Hz-step-a.png
Note that the dots that are not part of the main line/blob come in pairs, one 
above and one below.  I think that means one sample was late, so the previous 
step is long and the next one is short.

These are expanded to show only 2 minutes:
  http://www.megapathdsl.net/~hmurray/time-nuts/ppstest/60Hz-b.png
  http://www.megapathdsl.net/~hmurray/time-nuts/ppstest/60Hz-freq-b.png
  http://www.megapathdsl.net/~hmurray/time-nuts/ppstest/60Hz-step-b.png

These are zooming in on the step size:
  http://www.megapathdsl.net/~hmurray/time-nuts/ppstest/60Hz-step-c.png
  http://www.megapathdsl.net/~hmurray/time-nuts/ppstest/60Hz-step-d.png
The horizontal bars are because I've rounded off to a microsecond someplace.

These are zooming in on the offset:
  http://www.megapathdsl.net/~hmurray/time-nuts/ppstest/60Hz-c.png
  http://www.megapathdsl.net/~hmurray/time-nuts/ppstest/60Hz-d.png
The downward spikes are a delayed sample.  The upward spikes are "early" 
samples.  I assume it got lucky and the cache didn't get flushed or something 
like that.

Here is a histogram of the step size:
  http://www.megapathdsl.net/~hmurray/time-nuts/ppstest/60Hz-hist.png

This is a better view of the stuff along the bottom:
  http://www.megapathdsl.net/~hmurray/time-nuts/ppstest/60Hz-hist-a.png

Looks like 5-10 microseconds RMS of noise.  That's on a laptop that wasn't 
doing anything.


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