[time-nuts] Logging the grid frequency....

Hal Murray hmurray at megapathdsl.net
Fri Feb 22 13:47:05 EST 2013

dmendesf at gmail.com said:
> No, just designing a very wicked PLL and needing statistics of the
> frequency derivative... No generator is involved, it´s mains frequency  (but
> you gave me another idea... thanks!).

There is a lot of noise on the line.  I'm not sure if frequency makes sense 
on a cycle to cycle basis.

Two suggestions:

With a transformer and a few resistors, you can feed the line into the audio 
input on a PC.  Then you can search for zero crossings, run it through a 
filter, feed it to a FFT...

You can also feed the line into a modem control signal on a PC serial port.  
(USB probably won't work.)  The PPS logic from NTP will count cycles and 
record a timestamp on the last one.

These are my opinions.  I hate spam.

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