[RFI] What would cause noise like this?

Don Kirk wd8dsb at gmail.com
Sat Nov 2 08:08:01 EDT 2019

Hi Frank and gang,

I see lots of folks on the RFI reflector "wondering what an interference
waveform might be from", and honestly after many years of tracking down RFI
I have found that guessing what the source might be is almost counter
productive, except for understanding if the noise source might be power
line noise as that helps me determine what DF gear to pack.  What works
best for me is "boots on the ground', meaning that I get out DF gear (radio
direction finding gear), and then track down the property that's generating
the noise, and then we locate (track down) the offending device within that
property.  I find it much better to keep an open mind regarding what the
source might be.

Just my opinion based on many years of tracking down sources of RFI.
Tracking down RFI has unfortunately become a main part of my ham radio

Don (wd8dsb)

On Fri, Nov 1, 2019 at 7:30 PM Frank O'Donnell <vfo at inkbox.net> wrote:

> Hi all, new to this list, hoping to learn enough to chase down some of
> my yet-unsolved RFI issues.
> As a start, I'm wondering if the way that RFI I saw the other morning
> appeared in the receiver's waterfall might suggest anything about what
> the source of noise could be.
> Here are two brief video clips from SDR Console, displaying a waterfall
> covering the LF/MF spectrum with input from an Elad FDM-S2 SDR and
> broadband vertical antenna.
> The first clip is at 6:08 a.m. PDT, exactly one hour before local sunrise:
> https://vimeo.com/370416556/e3cf9bcb09
> At 00:23 of that clip, a pattern of heavy RFI starts, with lines in the
> waterfall spaced ~16 kHz apart (approx 6 lines per 100 kHz).
> A couple of minutes later, I noticed that the RFI started toggling, with
> the pattern changing for a second or two, and then the RFI disappearing
> briefly before restarting. In the following clip this pattern starts at
> 00:09:
> https://vimeo.com/370418392/afb0a0c4ef
> Any thoughts? We live in a suburban neighborhood where lots are all
> approx 50 x 200 feet. There are at least two houses with solar panels
> within ~200 feet of us, and more down the block. I gather that RFI from
> solar panels can vary, based on the type of system and the deficiency
> responsible for the RFI. Do these clips show any kind of visual
> signature that might suggest the source?
> Thanks and 73,
> Frank K6FOD
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