All true.
And of course if the noise is in the same direction as the signal you
want to receive these spatial discrimination techniques aren't much
help. I found that out early on when testing the first version of my
NoiseNuller app. I was listening to the local solar panel noise while
also transmitting a "desired signal" using a third antenna, but I didn't
get much discrimination at all. It turns out that the spatial phase was
the same for both, and when I transmitted the "desired signal" using a
fourth antenna located elsewhere on the lot it all worked.
73,
Dave AB7E
On 7/17/2026 1:15 PM, Jim Brown via Elecraft wrote:
Exactly right. And I've written extensively about techniques both find
and suppress sources. k9yc.com/publish.htm
But the real world part of the multiplicity of noise sources
surrounding us is that only one can be nulled at a time, and in my
experience, only on the low bands. An important limiting factor with
some sources is that they are physically broad as a function of
wavelength! For example, an array of solar panels, with or without
inverters, and their wiring.
73, Jim K9YC
On 7/17/2026 12:58 PM, David Gilbert via Elecraft wrote:
Of course that's the ideal solution, and of course lots of people
have done (or tried) exactly that and it often works. But I doubt
very many people are going to have much luck getting their neighbor
to replace their cheap solar converters with better ones, and I doubt
many people are going to convince the owners of the adjacent condo to
replace their cheap wall warts ... especially since lots of neighbors
aren't all that happy to have hams next door in the first place.
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