does anyone recognize this interference?

Jim_Shaffer

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Mar 31, 2013
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Screenshot-2025-06-12-182747.jpeg

For the past week or two, I've been seeing this pulsing interference across almost the entire HF spectrum. It's most visible here in the amplitude plot from 18-25 MHz due to the lack of other signals at the moment, but in the waterfall you can see it going down to at least 5 MHz. The other streaks that start at 0 and peak around mediumwave are probably lightning, and I suspect that the garbage from ~1500 kHz to ~3500 kHz is DSL, but I don't think that this new interference is DSL because first, I still only have 3 Mbps ADSL on my road, and second, it's not there full-time. Sometimes hours will go by without it, other times it's almost continuous.
 

krokus

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The two most common sources:
Switched mode power supplies.
Plasma TV/monitor.

It is likely to be from a neighbor's house. Using a small AM radio, and walking around the neighborhood with it, would help you localize the source.
 

dlwtrunked

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For the past week or two, I've been seeing this pulsing interference across almost the entire HF spectrum. It's most visible here in the amplitude plot from 18-25 MHz due to the lack of other signals at the moment, but in the waterfall you can see it going down to at least 5 MHz. The other streaks that start at 0 and peak around mediumwave are probably lightning, and I suspect that the garbage from ~1500 kHz to ~3500 kHz is DSL, but I don't think that this new interference is DSL because first, I still only have 3 Mbps ADSL on my road, and second, it's not there full-time. Sometimes hours will go by without it, other times it's almost continuous.
A common cause of interference like this is certain "reverse rotation" clothes washing machines. For that reason, due to a neighbors, I do not listen on Saturday mornings.
 

Jim_Shaffer

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Mar 31, 2013
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59
The spectrum looks a bit like grow lights, but it pulses on and off, at random times, so it's almost certainly not. (Also, do they wipe out 0-30MHz like that? Mine only wipe out longwave.)
 

IC-R20

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Nov 19, 2018
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A common cause of interference like this is certain "reverse rotation" clothes washing machines. For that reason, due to a neighbors, I do not listen on Saturday mornings.
Oh yeah I have one of those PWM motor new washing machines and it sucks. The noise travels really far and unlike when I had a plasma TV or a bunch of incandescent Christmas lights I can’t just walk out to the sidewalk with a portable or use the 10m groundplane on roof to get out of it.

Probably just a coincidence but I heard one of its noise sweeps at the same time on an SDR 110 miles away at the same time it happened on my local radio.
 
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