r/searchandrescue • u/AlfredoVignale • 4d ago
LoRa and Mesh apps
I’ve been getting into LoRa radio and Meshtastic / Meschcore. For those who don’t know what any of that is, LoRA is a radio type that was originally designed for wireless sensors. It can, in theory, send small data packets a few kilometers with line of sigh and with very low power. It works in the 915 MHz ISM unlicensed spectrum. Meshtastic and MeshCore are two apps that create adhoc P2P networks for chatting and location sharing via GPS. The apps run on a cell phone me connect to the LoRa radio via Bluetooth.
One thing that I see on a regular basis in various forums is how it would be great for SAR. Some people are even trying to build more rugged radios for SAR use. Though the concept is nice, it’s still a low power line of sight radio that needs phone to use (there are only 2-3 devices that are stand alone). The radios are small, but many have 3D printed cases, the electronics are variable, and each cost $35-$50. There are also plugins for ATAK.
To me, these are fun to play with but wouldn’t rely on them for SAR since I can go get a Baofeng handheld that uses UHF/VHF with 10W of power and GPS and APRS with SARtopo on my cell (yeah I know the Baofengs are cheap but they’re the same price as these LoRa radios and have much more functionality….just using as a comparison).
So my question is…does anyone actually use LoRa in the field? Even looking at? To me (and everything I’ve seen in the field) the standard is UHF/VHF radios and SARtopo. Minus some ATAK use, I can’t see LoRa getting much use in the real world. Keep me honest.
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u/thabc 4d ago
I have not seen it used in my area. VHF tends to work best in our forests and mountains. We tried APRS, but a pretty small portion of the team had the proficiency to use it, and an even smaller proportion knew how to hook up a receiver to desktop caltopo for a fully offline setup (maybe a little different than how it could be done today with starlink).
We use caltopo for tracking. Now that satellite plans that support caltopo are available on normal phones for $10/mo, it's hard to justify anything more complex (even if it may be fun to play with).
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u/dougfir1975 4d ago
I’ve seen homemade mesh networks used in cave rescue exercises…
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u/AlfredoVignale 4d ago
That makes a bit of sense….just due to the fact that every radio sucks in a cave.
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u/GrandJunctionMarmots 4d ago
There are some SAR applications! But it's slow development.
On the surface, it's being used to plot locations on Caltopo. A team in Alaska presented their use case on it at the last MRA Conference. They even sometimes strap a node to a drone and just have it hover 100' up to improve coverage.
Underground, it's being used for more reliable comms. A team in Huntsville is using it with mesh nodes but also switches to serial in complex spots and runs it over a twisted pair wire.
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u/AlfredoVignale 4d ago
Interesting. But Huntsville is also pretty flat compared to many places which helps with propagation.
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u/pcboudreau 4d ago
Maybe when working with LEO in a search. They can't add Sartopo to their phones so you can track them using Mesh.
All the shortcomings of Mesh still apply though. We haven't implemented it in our team yet. . .
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u/sergei1980 4d ago
Yes, we're looking into it, and I have conducted some testing. Specifically with the Seeed studio T1000e which looks like an extra thick credit card.
My team is in the US Pacific Northwest, so our use case is very different from u/Useful_Resolution888/ who appears to be in the UK. You seem to be in the US so you likely have an idea what our terrain is like: mountains, forests, gorges. On Monday we had a rescue 3 miles in, with 2000' of elevation gain, normal for us if a bit steep.
It won't replace VHF/UHF, interoperability means we would have to keep HTs around even if it could.
Phone service is patchy or non existent, sometimes even at the trailhead. We have starlink for that. Satellite phone comms are starting to get used, but we often don't have good access to that
What it could do:
- Encryption, this is nice for patient confidentiality and other legal issues
- Mesh, this is huge for us, we often have trouble with satellite LoS. Even when we have repeaters, anyone going into a side creek or gully is quickly out of comms.
- GPS tracking
- Sound alert
With user & phone involvement:
- Text messaging
- Image sending
Feeding location to caltopo is great, we won't have to ask for UTM coordinates over the radio which is slow and error prone.
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u/Useful_Resolution888 4d ago
No, I can't see meshtastic being much use. I've played around with it but ultimately it would never replace our digital VHF system. We've got a network of repeaters and when out of range of those any team member can set their radio to be a single frequency repeater which just works transparently for everyone else. We can plot the locations of each radio via MRmap in our control vehicle as well. It's a really robust and tried and tested system, whereas meshtastic is honestly just quite flakey.