[jkoberg]

What frequency band are you using? ISM is the only one that permits store-and-forward / automatic operation, as the gotenna people found.

You say a few miles per node - I am having trouble seeing how that's possible without elevating all the nodes

[punkgeek]

Oh yes, line of sight makes a big difference (also working as mesh helps for forwarding packets). Also we use a very high spreading factor so the bit rate becomes super low (with lots of chirps)

[superkuh]

He's gotta be assuming the nodes have clear line of sight and fresnel zone. The maximum distance for the link budget in a perfect situation. In practice it probably cuts off at the nearest rise in the ground or depression.

But they're still cool and I still want some for non-hiking applications. With the very low power idle and low cost they could be set up with solar panels in the tops of trees or in similar high height above terrain positions.

[generatorguy]

915 MHz goes a lot farther than 2.4 GHz.

At very low bit rates you need very little SNR.

There is probably very low noise out in hiking environments.

Yes, attenuation due to terrain is going to be a killer, but my experience with non line of sight 900 MHz links blasting through trees leads me to believe it would be workable for low bit rate data between a series of hikers along the same trail.

It is sending only location and text messages so intermittent link status or re-tries due to temporarily terrain/foliage obstructions will not cause degradation in service that you would experience trying to watch netflix over this mesh.

[myself248]

I used to get about a mile on 900MHz Ricochet radios, one of which was sitting on a chair in the living room, the other of which was sitting on the passenger seat of my car. Around a mile, the usable data rate would fall below 4800bps, and my NMEA packets would stop going through.

I find it entirely believable that a lower data-rate modulation could get better range than that, even on less power and worse antennas.

And you can do a LOT with antennas on 900MHz.

[hackcasual]

Their site says using 915mhz, and the radios they recommend are all LoRa devices, so that's probably the best way of evaluating distance performance.

[zensavona]

I actually fly FPV drones and it’s amazing how far I can go and what obstacles I can penetrate with my 915mhz 2W control link with very usable latency (good antennas makes a huge difference as mentioned by others). 2-5km through thick city buildings etc at times.

[arrty88]

Can you use MURS for this? Or potentially GMRS if the operators are licensed?

[gh02t]

Hmm... I'm pretty sure MURS allows for this type of traffic as of the last rules revision and would be ideal for this use with the higher power allowance, but MURS is a USA only thing so that kinda limits you if the goal is something that works all around the world.

OP is also talking about using off the shelf LoRa boards and their project is more about the software, so they are stuck with the bands available on the commercial LoRa transceivers those boards use.