Lightning Analysis With Your SDR
Maybe this is just one of the things that adults dream of entertaining their children, but have you ever been told to count the time slowly between seeing lightning and hearing thunder? The idea was that the number would tell you how far away the storm was, but from an adult’s point of view, the accuracy of calibrating a child saying “one … two … three …” in miles seems highly suspicious. This is a valid technique and can be used to monitor thunderstorms from radio emissions generated by electric shock. This is an area where the SAGE and they have published some details, including a fascinating exhaustion of software techniques, on how lightning can be detected with an RTL-SDR.
Lightning strikes produce a characteristic broadband explosion that appears in the time domain as a maximum point that can be easily detected, but can also be confused with radio interference from another source. Thus, after identifying the maxima, they magnify and perform a Fourier transform to detect the broadband explosion. Everything is done in Python and the pleasant surprise is how easy it is to understand everything.
SAGE is working on a distributed sensor network, so hopefully this work will one day give us real-time open lightning data. The FFT approach must ensure that it is not misled by false positives traditional detector can be.