[time-nuts] Recording mains frequency/phase [WAS: No GPSsatellites]

Ben Hall kd5byb at gmail.com
Sun Mar 1 16:10:59 EST 2015

On 2/27/2015 1:27 PM, Tom Van Baak wrote:
> There are many wonderful web sites that deal with power line
> frequency; some with live plots. Just google for words like: mains
> frequency detect accuracy stability measurement

Been doing just that - fascinating!  I'm getting closer to doing some 
frequency / phase monitoring here.

From:  <http://leapsecond.com/pages/mains-cv/>

"A convenient way to monitor power line phase or frequency is to 
timestamp every cycle. This generates a lot of data...so for most 
purposes we keep just one timestamp per second. This gives about 86400 
samples per day."

Using a zero-crossing detector with the picPET and logging the timing of 
each zero-crossing, how do you toss out the other 59 samples each second?

Doing this after-the-fact seems do-able with some software.  I seem to 
recall doing something like this with FORTRAN or BASIC.  (open log file, 
open output file, read log file line by line, tossing out 59 samples and 
writing the 60th to the output file, reach EOF, close both log and 
output file)

But...is there a clever way to do it up front?  Time to do more reading. 
  I've seen some folks doing frequency / phase monitoring using an 
Arduino, but nothing (yet) that uses a high-precision reference such as 
10 MHz from a GPSDO.

On a side note...the Z3801 got a new outdoor GPS antenna yesterday. 
Very happy with how well it is working:


thanks much and 73,
ben, kd5byb

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