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0 pointsCOGlory5y ago0 comments

I think that the mesh aspect of this would be a substantial improvement over VHF/HF radios. I'm sure I'm wrong, but I don't know of anyone that is running a mesh VHF or HF system in the mountains. I always carry my HAM when I'm out, just in case anyone else is, but obviously that's truly local communication and has the downsides that you mention.

With a strategically placed mesh network and some solar panels, you could potentially overcome a lot of the downsides of radio because you could target high areas, such as mountain peaks, to help bridge those obstructions.

I definitely don't disagree that the #1 safety device is a GPS/sat phone, but those are prohibitively expensive and most people don't have them. If we could get some solar powered radios along ridges, and a decent percentage of people carrying them, I think there could be a very comprehensive mesh network that would work for most needs. Bearspray is already pretty ubiquitous, I don't think it'd be that hard to get people to bring a $30 mesh radio with them as a routine thing.

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5 comments · 2 top-level

vvanders5y ago· 3 in thread

Take a look at the Ars article, it's really hard to get coverage in moderately flat areas over a reasonable distance(1m+). You also quickly start running into the Hidden Node[1] problem or the N^2 aspect of channel congestion(which is why LoRA has such low throughput).

Cell companies spend billions on this and even then you'll still have gaps outside of the metro areas, and they're using much more advanced modulations like CDMA and FDM/TDM with a central coordinator.

I've talked with a fair number of people who maintain commercial repeaters in mountain areas and those can be incredibly difficult(combination of hard access in winter, large temperature swings and theft of solar panels/batteries) so which it might be possible, my guess is the level of investment just doesn't pencil out for the usage.

[1] https://en.wikipedia.org/wiki/Hidden_node_problem

bronco210165y ago

From some quick Googling it looks like LoRa accounts for the hidden node problem by using varying timing? Sure, it increases the amount of time required to send a message but as long as the device continues to attempt until it gets an ACK it seems like this could work? Of course, it also eats up the available airtime for the mesh but that's the trade off right?

I'm not a radio hardware expert and I'm not fully up on LoRa or the code of this project at all so I likely have no idea what I'm talking about. Was just wondering if someone else does?

COGloryOP5y ago

Thanks for the detailed response!

vvanders5y ago

No problem, it's a really neat domain and there's a fascinating intersection of physics + math(you can reconstruct freq mixers/modulation with a basic trig foundation) and practical application that makes radio a really cool space.

I also think that there's still untapped potential for secondary services and the like so it wasn't my intention to dissuade anyone form picking one up and giving it a try.

vegardx5y ago

I would be surprised if it was cheaper than something like a Spot or Garmin inReach when you factor in the cost of building out and maintaining such a network.

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