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Due to planned maintenance, the electric power in my neighbourhood was disconnected for hours today. That offered the opportunity to study the effect of background noise emitted from electric appliances.
(c) Anders Fongen, Oct 2024
When listening to the radio on the HF band, one can hear a lot of background noise which reduces the clarity of the reception. The emitters of the noise can be near or far away, which is interesting to distinguish, since the sources near you can be eliminated, most easily by packing your radio gear and drive somewhere else, to your cabin or into the mountains.
The neighbourhood which I live in had a power outage today, due to planned and announced maintenance. The affected area was small and included only 32 households (see map below). This disconnection gave me an opportunity to study the effect of radio spectrum noise (particularly in the HF region) from this area. The Xiegu G90 was powered by a battery and conncted to the outdoor antenna, then tuned to the 20 meter band in USB mode.
I enjoyed the clarity of the reception and had a few QSOs before the electric power was expected to return. The radio display was filmed that moment when these 32 households again was able to power their cable modems, dimmers, plasma TVs, routers etc., and the difference in the receiver conditions was remarkable, which can be seen in the 20 seconds clip below.
Please observe the waterfall display as the power returns, and how excellent signals become completely drowned in the elevated noise floor, totally invisible in the waterfall.
After the power had returned I also switched off the main circuit breaker in the house to informally identify how much of the noise was coming from my own home. Hmm, quite a lot, since I have two wireless routers, ethernet switches, and dozens of wifi-connected house appliances. They are, like appliances in my neighbours’ house, essential for the daily life of our home, and cannot be switched off anytime.
From this experiment, I now realize how much the reception quality can be improved by taking the radio gear somewhere else (my home town is surrounded by mountain areas easily accesible by car) and operate a mobile/portable configuration.