On 1/31/2023 9:21 PM, K9MA wrote:
My QTH is in an older residential area, surrounded by overhead power
lines. Line noise is a constant problem. We recently had a major power
outage, so I measured the noise levels to get a baseline with little
line noise.
Hi Scott,
How do you know that it's line noise, not electronic noise? 25 years
ago, line noise was a good assumption for anything we heard on the
bands, but in almost any developed area, the average home has a couple
of dozen electronic sources, everything from switch-mode power supplies
for everything that plugs into the wall, variable speed controllers for
motors, computers and lots of other stuff with microprocessors in them,
and on, and on. When the power goes out, so do all of those electronic
noise sources (except for those that UPSs keep running).
The slides for talks I've done at Pacificon, Visalia, and to some clubs,
show how to use a well-adjusted waterfall to differentiate between
impulse noise (which is what line noise is) and electronic noise.
http://k9yc.com/KillingReceiveNoise.pdf
Yes, those with ear experience can nearly always tell the difference.
NK7Z has wonderful advice and resources on his site about using 24 hour
very wide waterfalls to yield clues about operating hours of both
impulse and electronic sources, and also recognizing multiple electronic
sources.
73, Jim K9YC
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