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Grow Light RFI
RFI occurred daily with 12Hr On/12Hr Off cycle to 18Hr On/6Hr Off cycle, killed most HF Bands, especially 40 meters.
Single home grow light operation on 80 Meters, one block away. Shows approximately 24 hours of time. Time along vertical axis, frequency across horizontal axis, and intensity indicates signal strength.
Single home grow operation recorded in realtime from one block away from RFI source. The horizontal lines are an electric blanket, recorded from about 50 feet from teh blanket.
The sames single home grow light operation, shown above, only on 80 THROUGH 40 Meters. Time runs along the vertical axis, and frequency along the horizontal axis. Brightness indicates intensity.
Look at around 0848 UTC in the 80 meter portion of the spectrum. You can see an RFI source start up, then drift first up, then a few hours later quickly down, then suddenly it reverses, and starts a slow upwards drift across the next 7 or more hours. That is a known grow light.
If you also look in the 40 meter portion, you can see what appears to be the same source, with the same hook action! I am thinking the brightened hooked area in 40 is overlap of the bands of RFI this light system generates… I suspect this location is a full grow house, with multiple lighting systems in multiple rooms.
Look at 4.77 MHz., on the spectrogram you can see some CODAR from the coast about 60 miles from me. It is the series of short slanted lines. This spectrogram was taken across about 20 hours, so the slant is an artifact, not a real-time view, although it looks surprisingly like that in real-time.
At 6.88 MHz., I see what I think is the Chinese over the horizon radar that moves up and down into and out of 40 meters…
You can see all the SW broadcast stations in the 6 MHz region.
All of this is being taken using an SDRPlay RSP1, and a BWD-90 broadband dipole.
Here is a pair of movies I created, time runs vertically, and frequency runs horizontally. Each movie covers a 24 hour period of time. All RFI is from the same location.