Lightening distance detector. - Page 1
Forum section: electronics / beginners

author: paulca
author_rank: Super Contributor
timestamp: September 14, 2025, 10:35:05 am
content: When I was a kid I wrote a BASIC program on my AmstradCPC464 which would tell you how far away a lightening strike was if you pressed the space bar when you see the flash and again on the first peel of thunder. Not exactly complicated.Today, if I put a chromatic sensor and/or a photo diode set to trigger on "high intensity pulses" and a microphone amp and filter setup to detect "sub sonics". I could do this automatically.That was very easy to say though. I see many fit falls.Testing it, the photo part would need to be tricked by a camera flash. The audio part, best I can do is about 18Hz from a headphone. Unless I make a device for the purpose.I know there are other ways and more than can be done with a device like this. You can with some rudimentary RF gear triangulate the lightening bearing and range from the RF spike. However that includes "RF" and thats my nemesis. Trying to time the arrival of two RF spikes from two antenna to the nano second ... no thanks. Not unless they sell the on AliExpress.However... with a MEMs microphone array and an FPGA multi-delay capture, a bit of (probably off github) code and I could make a "phased sonar" to give a ball park bearing and maybe? An approximate range? It's an awfully small triangle if the array is only 6 inches across right.Testing it for real would be a challenge. I live on the NE end of Ireland, the prevailing wind is SW, so you can sit and watch lines and packs of thunder cells move up the middle of Ireland and pass straight by my area hardly ever coming with in 10 miles. The only time we see thunder here is when there is northerly cold front, following a warm and that mostly happens in winter when there isn't enough energy for thunder unless it's snow static.

author: jpanhalt
author_rank: Super Contributor
timestamp: September 14, 2025, 11:14:20 am
content: The Ryan Stormscope from decades ago* used a proprietary method to calculate distance. AMS made the Franklin Lightning Detector chip AS3935 that also calculated distance from a single point. (It appears to be made by another manufacturer today with the same chip number.) AMS did not divulge its algorithm, but intensity seems to have been a factor.More on topic, lightning storms in my experience have many more flashes than distinguishable thunder. Much of that is probably cloud to cloud. How will your sound based system determine which flashes are associated with a particular boom?*Went through a series of acquisitions and according to Google is now made by Astronics.

author: Andy Watson
author_rank: Super Contributor
timestamp: September 14, 2025, 11:57:18 am
content: The RF detection is not that demanding. If I remember correctly it requires a sub-300kHz reciever - it could easily be achieved with op-amps or a re-purposed AM radio. These sites operate a network of "stations" for reporting lightning world-wide. There used to be plans available for the local receiver stations but I can't find them nowhttps://www.lightningmaps.orghttps://www.blitzortung.org

author: jpanhalt
author_rank: Super Contributor
timestamp: September 14, 2025, 12:32:49 pm
content: Here's one I made awhile back copied from somewhere on the Internet. There are lots of variations. Real fun to watch on a scope. I also made a simulator based on the AMS design, if interested in using a LF approach.

author: ledtester
author_rank: Super Contributor
timestamp: September 14, 2025, 02:24:53 pm
content: Concerning the blitzotrung project, here is a design document from 2010 which I've also attached below:https://www.blitzortung.org/Compendium/Documentations/Documentation_2010-12-25_Green_PCB_6.5_PCB_5.5.pdfThey used an AVR mcu running at 20 MHz and the input was sampled at 320ksps by external ADCs.

author: radiolistener
author_rank: Super Contributor
timestamp: September 14, 2025, 02:42:43 pm
content: That’s a really interesting line of thought, and you’re right about the pitfalls with timing and sensor sensitivity. One more factor that often gets overlooked: if you live in or near a built-up area like large city, reflections can completely confuse the acoustic side of such a system. For example, we often have bomb blasts in the city, and the first impression sometimes misleading — the sound may bounce off buildings and arrives from different directions with small delays. You can actually hear it "move" from one side to another, and sometimes it becomes very hard to tell where the source really was. With thunder, especially in a city, you would face the same issue: echoes from large structures could distort both timing and bearing, so the array might show inconsistent or even opposite directions.

author: Marco
author_rank: Super Contributor
timestamp: September 14, 2025, 06:30:15 pm
content: Quote from: radiolistener on September 14, 2025, 02:42:43 pmThere's probably a right way to do this ... but naively I'd use three mics, take the average, then correlate the signals with the average. As long as there is line of sight, you'll be able to fish out the first peak for the direct signal. With 3 mics you can differentiate front and back, assuming it's mounted up high somewhere.

author: Analog Kid
author_rank: Super Contributor
timestamp: September 14, 2025, 08:23:32 pm
content: Very small note: it's "lightning", not lightening.Lightening is what Michael Jackson did.

author: jpanhalt
author_rank: Super Contributor
timestamp: September 14, 2025, 08:31:55 pm
content: Thank you Miriam the librarian (Music Man).Edit: Marian

author: Analog Kid
author_rank: Super Contributor
timestamp: September 14, 2025, 08:37:41 pm
content: Quote from: jpanhalt on September 14, 2025, 08:31:55 pmThat's me. (Ackshooly it's "Marian the librarian". I played that musical in high school.)

author: mikerj
author_rank: Super Contributor
timestamp: September 14, 2025, 09:35:21 pm
content: The very long wavelengths of thunder (~3m to 86m assuming most of the energy is in the 4-125Hz window) would make a small phased array useless for direction finding IMO.

author: 5U4GB
author_rank: Super Contributor
timestamp: September 15, 2025, 03:22:36 am
content: Blitzortung is still going strong, if you don't mind spending a bit of money and doing it properly I'd recommend going with them. Otherwise there's theAS3935which isn't bad for what you can do with a single-chip device but nothing like what the Blitzortung setup will get you.

author: jpanhalt
author_rank: Super Contributor
timestamp: September 15, 2025, 09:05:47 am
content: Blitzortung apparently looks at VLF (<~50kHz), the AS3935 and I believe Stormscope are tuned to around 500 kHz.If you want a quick start, Thunder Click by Mikroe (https://www.mikroe.com/thunder-emu-click) is <$20 USD. You'll need to write a little code to read the results, but that's relatively simple to do. I used a measley PIC16F1xxx.

author: 5U4GB
author_rank: Super Contributor
timestamp: September 15, 2025, 11:48:04 am
content: By a timely coincidence, a Blitzortung user has just posted adetailed writeup on getting a station up and runningfor anyone interesting in finding out more about the Blitzortung hardware and config.