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Comment by Catbert59 | Hacker News Reader

There's also Blitzortung.org which is a very interesting project.

They are receiving Sferics on the lower HF frequencies and tag them with GPS timestamps (with the PPS signal they are in the Nanoseconds precision range). A central server will then do the triangulation.

All with off-the-shelf hardware (STM32, etc.).

Their service is stable for many many years now.

(Offtopic: The STM32H7 ADC is great for many many things)

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Whenever it thundered I used to love to take out my shortwave radio, tune into some empty frequency and be able to hear each individual lightning strike in realtime (even more realtime than the speed of sound would allow!)

You can look at lightning in an SDR receiver, they look like horizontally oriented stretched droplets. Somewhere around 7kHz iirc.

I tried to detect lightning with a Bosch Sensortec COTS magnetometer - but failed.

Was a fun experiment: https://www.dm5tt.de/2025/07/26/thunderstorm-detector-with-m...

I’d like to ask to repeat this experiment but with a ferrite core next to the sensor (touching it). On the low spectrum (below a few MHz?) the magnetic component in the electromagnetic wave becomes dominant. Which is why receivers in shortwave radio and in e.g. DCF77 use a ferrite antenna. The ferrite’s length should be perpendicular to the line formed by the sensor and the location of the storm.

Edit: you’re reading at 400 Hz so you’ll read phenomena below 200 Hz

Will do. The experiment isn't yet dismantled.

Going to write the ferrite core on my next shopping list.

Blitzortung is a little long in the tooth. Great tech, but the mapping doesn't let you get any detail. Lightningmaps.org scrapes the feed but will sometimes just completely stop functioning and never come back.

> The STM32H7 ADC is great for many many things

Is it any different from the ADC on other MCUs?

Not really. Just very good ones.

I also work a lot with ESP32s. Their ADCs (non-linearity, and with the integrated calibration you loose resolution) don't make too much fun.

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