Hi Jim (AA5CT),
Yep, I too had 3 phase in the back of my mind when looking at the frequency
of the major peaks. Sure will be interesting to see what Ken finds the
source to be.
Thanks for the comment.
Don (wd8dsb)
On Fri, Jan 10, 2020 at 8:36 AM AA5CT <jwin95@yahoo.com> wrote:
> Don,
>
> Toss this into the mix:
>
> Three phases times 2 ppc (pulses or strikes per cycle) gives those
> six 'peaks' seen in the 16.66 ms cycle duration between the cursors
> in that screen capture.
>
> Take a look and see if I missed or misinterpreted something.
>
> de AA5CT
>
> .
> .
> On Friday, January 10, 2020, 7:18:32 AM CST, Don Kirk <wd8dsb@gmail.com>
> wrote:
>
>
> Hi Ken,
>
> Thanks for the additional 17 second recording with no human voice on top
> of the noise, and this is what I really needed. I looked at the audio
> using my 100 MHz digital oscilloscope, I looked at the audio using
> "Audacity" software, and I looked at that audio using "Soundcard Scope"
> software, and all 3 methods yielded the same results. I have attached the
> screen shot from "Soundcard Scope" as it's a good representation of what I
> see. There is indeed a repeating pattern that happens at a frequency of 60
> Hertz.
>
> If you do FFT analysis on the signal you will also see strong component at
> 120 Hertz and other related harmonics in addition to the strong 60 Hertz
> component, but I'm not convinced that means anything as you can also
> imagine you are seeing bursts at a frequency of 360 Hertz too (looking at
> what I would call major peaks for each small grouping I see a frequency of
> 360 Hz), and 360 Hz is also one of the dominant frequencies in the FFT plot
> (spectrum plot) generated with the Audacity software.
>
> Would love to hear comments from others regarding their opinion of what
> they see in my attached plot. As I previously stated, it's interesting to
> look at the audio signature but what counts is locating the offending
> device using DF gear versus guessing what it might be. It will always be a
> guess (sometimes an educated guess) until you find the device.
>
> Keep us posted on what you find, and let me know if there is anything else
> you might need.
>
> 73,
> Don (wd8dsb)
>
>
> Bottom line is that I am seeing repeating pattern at a frequency of 60
> Hertz.
>
>
>
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