[Elecraft] Noise Nuller

[David Gilbert]

Hi, Mike.

I tried it with FT8 a couple of times but I the local solar panel noise 
I hear is pretty narrow band ... just a few KHz wide.  It moves around a 
bit but so far I haven't been able to find it overlapping the FT8 
frequencies.  My noise otherwise is pretty low.

We're in the middle of our monsoon season now so I have all my antennas 
disconnected, which means I can't even do a proper simulation.  Sorry ...

The app is pretty easy to set up, though ... but of course it needs two 
antennas (almost ANY two antennas) and two phase locked receivers to 
work.  If you have that you should be able to decide for yourself 
whether the app helps or not.  Keep in mind that anything that's from 
the same direction as the noise is going to be discriminated against 
almost as well as the noise.

73,
Dave AB7E



On 7/19/2026 5:01 PM, Mike Fatchett W0MU via Elecraft wrote:
> Have you test the app with FT8 or FT4.  I have found that line noise 
> or hash will impact receiving.  They say that FT modes can handle the 
> noise but I have found that a WNB or NB is required when a particular 
> noise is present.
>
> Mike W0MU
>
> On 7/17/2026 5:02 PM, David Gilbert via Elecraft wrote:
>>
>> 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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