On 11/19/2023 5:46 PM, Stephanie WX3K wrote:
I was finally able to capture it again with a wider span
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November 19, 2023 <https://youtu.be/Haz0-f8s318>
youtu.be <https://youtu.be/Haz0-f8s318>
<https://youtu.be/Haz0-f8s318>
This is clearly power-handling electronics, the most common sources of
which are switch-mode power supplies for equipment that convert 120V AC
to the fairly low DC voltage used by almost everything that we plug into
the wall. The average home has several dozen of these noise makers.
Other common sources include controllers for variable-speed motors that
run everything from HVAC systems and heat pumps to elevators in public
buildings. Equipment in factories are another potential source.
This noise is NOT sinusoidal -- we're looking at frequency spectrum.
Each one of those humps is a harmonic of the switching frequency used in
the equipment generating the noise. What appears to be sinusoidal is
modulation of the carrier by noise.
Now it's time to doing some direction finding. It's NOT power line
noise, but it could be from a source connected to the power system, like
lighting, chargers for battery backup, etc. But it's NOT the arcing
(impulse noise) that is characteristic of virtually all noise generated
by defective equipment in the power system itself.
Follow suggestions in my noise tutorial about probing for sources in
your own home with a battery operated receiver. k9yc.com/publish.htm
73, Jim K9YC
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