Background noise in the radio spectrum

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Due to planned maintenance, the electric power in the 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.

The map showing the extent of the affected households

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.

Video recording of the moment when the power returned to the neighbourhood

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.

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