[time-nuts] 60 Hz frequency and phase measurement

[jimlux]

On 7/2/19 10:09 PM, Bob Albert via time-nuts wrote:
>   I have tried to measure the power line frequency with spotty success.  My best results came from a period measurement, as many periods as the counter can accumulate.  Due to noise, one is never sure at quite what point the source is measured.  Perhaps a brick wall filter would clean it up for a more reliable measurement.
> Of course, at 60 Hz the period is 16-2/3 milliseconds.  So the counter should properly show a 1 followed by a row of 6s, with the last digit bouncing between 6 and 7 most of the time.
> If there is a filter used, it will not only remove noise but also short term variations.  But generatlly speaking you don't want to measure those, unless you are trying to evaluate a rotary generator.
> Getting this reading can be a challenge.


The idea would be to look at the phase variations over time across a 
neighborhood and see if you can see effects from people turning on and 
off loads (air conditioners and sags causing light flicker  brought up 
the discussion).

It's a whole lot easier for someone to ask "can I put this little 
recording box here" than "can I plug something into your wall socket"

The idea is that you get cheap GPS receivers as the time hack and record 
*something* at a suitable rate after some low pass filtering, and then 
post process.   1kHz sample rate for a day is 86 Megasamples, so it's 
not an enormous dataset that needs to be recorded.

Maybe it's just time [sic] for an experiment - stick a wire on an ADC on 
a Beagle or Arduino and make some recordings.








>      On Tuesday, July 2, 2019, 10:01:03 PM PDT, jimlux <jimlux at earthlink.net> wrote:
>   
>   On 7/2/19 4:09 PM, Dana Whitlow wrote:
>> I've always noted that casual attempts to pick up 60 Hz with small antennas
>> etc see more harmonics and other trash than actual line frequency.  But if
>> you're in an office environment, why not plug something in?  It's quite easy
>> to build a simple passive diode clipper/filter that will plug into a wall
>> outlet and
>> which will provide a sort of soft (but clean) squarewave at a voltage level
>> convenient for lab instruments and with good protection against big spikes
>> and
>> other trash riding on the line.
> 
> 
> Safety approvals are one obstacle (of course one could use a AC wall wart).
> 
> Actually, it's because someone asked me about a science experiment where
> you'd place them in a neighborhood outdoors.
> 
>