I had two intermittent noise sources that the NB was marginally effective on.
One was the dishwasher, the other a flat screen TV. Not plasma, but an older
LCD fluorescent backlit model.
Al
AB2ZY
-----Original Message-----
From: TowerTalk [mailto:towertalk-bounces@contesting.com] On Behalf Of K9MA
Sent: Saturday, January 02, 2021 10:36 PM
To: towertalk@contesting.com
Subject: Re: [TowerTalk] Weird RFI at remote location
On 1/2/2021 8:32 PM, Ignacy Misztal wrote:
> 1. The noise is originating from one location because otherwise NB
> would not be able to blanket it.
I don't think so, unless you are using some sort of noise cancellation
with two antennas etc. Noise blankers can be very effective against
impulse noise, typical of line noise. However, they don't work well if
there are strong signals within a few kHz. While it's a good diagnostic
sometimes, a noise blanker that works on a quiet band probably won't be
useful during a contest.
Besides its impulse nature, line noise is usually quite broadband. While
it may affect one band more than another, there generally isn't much
variation in strength within a band. This is very unlike noise from
switching supplies, motor drives, etc, which usually show peaks at
harmonics of the switching frequency, often 10-100 kHz. As others have
suggested, the difference is most readily apparent with a spectrum
display. It's a lot harder to discern by tuning around looking at the
S-meter, though it can be done.
Because I live in the city surrounded by overhead power lines, I have
way more experience with line noise than I'd like. Hopefully that will
be of some use to others.
73,
Scott K9MA
--
Scott K9MA
k9ma@sdellington.us
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