So, I’m scratching my head, and hoping someone here can help, or have had a similar experience?
I live at 500msl in a small rural town of about 300 people. Started experimenting about a month ago and have a few T1000-E’s and a station g2. The waterproof enclosure I ordered for the g2 finally arrived a few days ago and it’s now up on a modest pole attached to my house (about 4m high), signal is much better and we only have 3 regular members of our mesh at this stage (still testing before advertising to locals).
Even before raising the g2, we’d had a few times when a couple of nodes would appear for a few hours in the early hours of the morning. We are in an area popular with hiking and 4wders so this isn’t particularly unlikely especially as these are given as ideal use cases for Meshtastic, and sometimes people do get up early for this kind of thing!
But last night, we had an absolute explosion of nodes in the early hours. All had gps locations of around a very specific area on the coast, approximately 180km away as the crow flies. I think one or two of them had been seen before but I’d wiped my nodeDB a few times since then so not completely sure.
The similarity to previous times when we saw a few nodes in early hours, but many more (with g2 higher, makes sense regardless of how), makes me wonder now if something atmospheric is happening.
Could this be tropospheric ducting? If so has anyone managed to actually communicate with this kind of connection over MT?
Yes, it’s a heat inversion, similar to how a highway will shimmer during the summer heat. Because the air is warmer at higher altitude than it is at lower altitude.
The technical name for it is a tropospheric duct, as you mentioned above. And no, I have not been able to communicate with nodes reliably over it. I think I did manage it once, but I never got a response back, so I’m not certain if it went through or not.
Thanks! That’s super exciting. Will try and send out some DMs next time it happens - just to get the more reliable ack. I doubt many people are awake at the times it is probably strongest signal though.
No idea. Might also have been someone in a plane right above. We have had nodes appear that were all across the state, then disappear after about 30 mins because someone in a plane had a mesh device.
Fairly unlikely it was a plane due to the time frame in which the nodes were refreshing - was over at least 4 hours from when the first distant node was seen, to no longer seen / refreshing. And all the nodes were apparently from this one distant area, which is about 4-5 hours drive away, because it’s on the other side of a big bay. And didn’t see any other familiar nodes that were closer, of which there are quite a few.
Try meshmap and have it running for a while. If it’s consistent, you will get more info either way.
Good point! I didn’t think to do that to check positions, that would have confirmed if the gps was accurate. But one new comment had confirmed that it could indeed have been a tropospheric duct, which is quite exciting, as I didn’t realise that was possible with LoRa, and don’t think I had seen mentioned before, even though I had read about AR events where DX occur, TV signals etc. So cool!
I agree with the plane theory, one time my nodes were hopping to a plane and reaching nodes in Canada with the farthest node reached being 115mi/185km
As far as I know the frequencies Meshtastic plays with doesn’t really do anything crazy when it comes to propogation. That’s why good line of sight is so vital
So what you’re saying is, we all need to bring our nodes in the air? lol
Hmm. When you’ve hopped a plane, have they tended to be a cluster of nodes? I guess if it was a node on a flight from a particular airport it’s maybe possible… I need to go look at flight info, we’re not in an area with much air traffic at all, and the time frames don’t make sense, how could they keep refreshing for hours? 🤔 And the time of day, there’s just not usually flights occurring in the middle of the night here either.
You can look at ADSB history to see if a plane was in the area then
For me the initial signal from the plane was at 30k ft and about 40 miles away.
This is just a hypothetical, but have you compared the SNR of your local nodes throughout the day? It could be that your local noise floor gets lower at certain times and allows you pick up further signals.
I’ve seen similar results where I get nodes from a town about 100 km away, but only around 8 PM. My local nodes SNR around that time is ~4 dBi higher than normal.
That is an excellent question! I have noticed it can change, and have been paying more attention to those numbers since raising the station g2, but this is a really oddly specific collection of nodes, all from one place. Maybe I should post a pic…
Is it possible that one of the devices has been connected to the Internet and those new nodes you see come from MQTT? You can disable that option if that’s the case.
I’m not sure, there’s lots of nodes closer, I would have thought if there was an MQTT connection that would see them first not a specific location further away? 🤔
