That's good input from Don.
Most inside sources are present at 60 and or 120 hertz, whether a sparking
source or not.
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On Jan 10, 2020, 8:18 AM, at 8:18 AM, 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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