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Guys,
Thanks for the responses. I was thinking only in terms of the the most basic first principles of radio propagation, and now I see that that's probably not a reasonable approach. Making reasonable assumptions about the relative signal power in different frequency segments of a lightning strike, and then knowing something about the attenuative properties of moist air to those frequency segments, could clearly work, and I don't doubt that's what airborne lightning detection does. Of course, now you're in a situation that requires one to know something about lightning and something about air, but I guess that's life! Now I'm really curious to see a spectrogram of several lightning strikes to see what's predictable about them! thanks again, -- dave j, PP-ASEL, no lightning detection on board ![]() David Rind wrote in message ... You can find a number of websites that can provide a better description than I can, but the basic concept is that: 1) The intensity of most EM bursts from lightning over a range of frequencies is such that the strength at a given frequency is proportional to the strength at other frequencies. 2) Some frequencies suffer very little atmospheric absorption and so give an unabsorbed measure of the strength of the lightning. 3) Some frequencies are significantly absorbed by the atmosphere. 4) By comparing the unabsorbed frequencies and the absorbed frequencies, you can make a reasonable guess as to how much atmosphere the EM burst traversed getting to the receiver, and so can predict how far away the lightning was. |
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