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Comment by COGlory | Hacker News Reader

This is absolutely brilliant. If this works as advertised, it'd be trivial to add mesh network capabilities to lots of the mountainous areas I'm frequently in while hunting or hiking or what not. That would be huge for safety, and substantially cheaper than a sat phone.

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> safety, and substantially cheaper than a sat phone

I agree that it's a really cool project but I personally would not use it as a primary safety mechanism.

I've got a ham radio license and I see the same mistake with people who think a 5W VHF handheld or 10W HF radio will help them in dire straights. HF isn't reliable enough and all it takes is a little terrain to block VHF. You're also not guaranteed that there's even anyone on the other side of the radio if you really need help.

I would recommend a SPOT or inReach as a your primary safety device with this as a (neat) backup. All they need is a line of sight to the sky which is much easier to do than either LoRA, VHF or HF.

[edit]

If you want a good idea of the limits of LoRA Ars did a pretty good write-up a few years ago: https://arstechnica.com/gadgets/2019/10/lostik-usb-lora-radi... . You'll see that even in a few mile radius there's plenty of places where even a high-end LoRA device drops out because very few radios can go directly through terrain(if you're curious https://en.wikipedia.org/wiki/Through-the-earth_mine_communi... covers some aspects).

It is a really cool modulation for low power but it's still subject to the physics of radio propagation.

I'm in mountain rescue and I'll second all of this. It's why we will set up repeaters, or station people as repeaters if we have enough people, but more often than not, we are out of radio communication for hours on end, despite all parties having the necessary equipment. More often than not, we'll use inReach texting to maintain comms.

But projects like this excite me for future directions. Sometimes when we've been in areas with cell phone coverage (some wilderness in SoCal has coverage), we will be able to see tracks in SARTopo update live from teams in the field. It's really cool when it works!

Yes!

I'm totally 100% on board with this as a secondary data/telemetry mechanism.

For all the open source software out there it's a tragedy that there's less of that culture in ham radio(which is one of the primary charters of the spectrum-carve out we have). Stuff like this and the M17 project give me hope that we might some day have something more than just the dumb AX25 packet radios(which are stuck in the 80s at 1200bps and zero FEC).

Not able to reply to the sibling comment from bsder, but yes, encryption is forbidden in the ham bands.

What vvanders is talking about, and it's a massive point of frustration for me too, is that all of the layer 2 open standards that have actual use are ancient. Like, we're supposed to feel lucky that we whave ARQ. Ridiculous.

It's not really anything to do with encryption or indecipherability, but all about spectral efficiency, and most of that really comes down to coding. I can pop open fldigi and generate a 64QAM signal really easily, but actually coding the data to ship over that pipe starts getting into some pretty arcane territory.

Think about just how good a modern cellphone is - 100+ megabit connection in the palm of your hand, competing for spectrum with hundreds or thousands of other devices, with a handset power of less than 1 watt (usually). There's nothing inherently magical about it, it's just not something that there's a lot of FOSS work around.

I've been working on deep diving on this a lot lately, I really think there should be more open source libraries around coding, but I have a funny feeling anyone who gets good at this gets snatched up by someone in the 3GPP consortium.

> Stuff like this and the M17 project give me hope that we might some day have something more than just the dumb AX25 packet radios(which are stuck in the 80s at 1200bps and zero FEC).

Isn't there some weird regulation about "non-decipherable" communication holding back usage of Ham bands?

Not really, as long as you publish a spec and it isn't encrypted(except for some really rare satellite control use cases) it's fair game.

The really annoying one is they put symbol rate into law instead of bandwidth so we'll never see above 9.6kpbs in the VHF bands(there was a petition a while back to repeal it but from what I recall a bunch of HF folks though it was going to cause chaos across the bands and I don't think it went anywhere).

Wasn't able to reply when I first saw this, I think because it was too new a comment - posted a long-winded reply as a sibling though, but generally it's not a matter of regulation, just a matter of interested and skilled parties willing to donate their time.

> I would recommend a SPOT or inReach as a your primary safety device with this as a (neat) backup. All they need is a line of sight to the sky which is much easier to do than either LoRA, VHF or HF.

I have quite a bit of experience with both, and wouldn't recommend either as a primary safety device. PLBs are far better.

SPOT is based on Globalstar, which leaves one without coverage in many areas. I also found it to be incredibly flaky even in areas of allegedly great coverage with a totally open sky.

inReach is vastly more reliable, and with global coverage, so if I was buying one for a (secondary) safety that would be the easy winner of the two. It also has the added benefit of bringing a convenience that PLBs don't, as one can grab weather updates and easily text others for information.

That said, it's not difficult to get into a situation where terrain makes quick satellite acquisition very difficult, and one could wait hours for a message to get out. PLBs are much more reliable in adverse situations (N-S slot canyons), have higher power output than satellite messengers, and are generally built to higher standards. They also don't require a monthly fee.

A legitimate PLB would give one more paths to a swift rescue, especially if SAR aircraft are already up and looking for you.

More info: https://www.backcountrychronicles.com/delorme-satellite-gps-...

Are there PLBs that let you actually text now? I’ve been told that many have been abused and are not treated as urgent any more, so a device like an in reach where you can actually communicate your situation is preferred. It also means rescue could arrive with the supplies needed for a particular injury, which makes a huge difference in some evacs.

> I’ve been told that many have been abused and are not treated as urgent any more

There is an old type of PLB and a new type. That was a problem for the old type, in principle. In practice, the search coordination centres got pretty good at triage. Going down Route 66 at 70 mph, unlikely to be a real emergency; halfway up Mt McKinley, scramble the chopper. Accidental activations are far more common than abusive ones.

The new type broadcasts its serial number, and everyone is required to register an emergency contact person when they buy their PLB. If the beacon is activated, the contact person gets a call from search and rescue, asking what the beacon user is up to.

What PLB do you recommend? I got an inReach because I was so overwhelmed trying to sort out the various PLB options

The ACR ResQLink View is usually a good default choice. I've read good things about McMurdo, but everyone I know who has need for a PLB carries an ACR, either the older 400 or the newer View, which I would recommend over the 400.

But just as an inReach isn't a replacement for a PLB, neither is a PLB a replacement for an inReach. It's great to be able to communicate in emergency (and in many non-emergency) situations.

Thank you. I'll be buying an ACR ResQLink View as soon as my budget allows. I appreciate the reply!

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.

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

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?

Thanks for the detailed response!

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.

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.

Do you know if there's an open source PLB like the inReach?

Just a side note that InReach/Spot are not PLBs, nor are they sufficient for situations that call for PLBs:

https://www.backcountrychronicles.com/delorme-satellite-gps-...

I've carried SPOT/inReach/[Iridum/Globalstar phones] extensively in remote areas, and while they are nice to have for convenient communication, I experienced enough issues with each that I would never rely on them in a life-threatening situation.

Not to my knowledge, given that a false activation of a PLB still calls the calvary I'd be hesitant to use something that wasn't extensively tested.

Careful you don’t expect too much here. At long range the bandwidth is very very low and latencies are very very high. Meshtastic will never be a replacement for a sat phone. Think of it as more like a two directional pager. Short text messages with latencies possibly as high as 40 or 50 seconds.

Lots of people disappear from the forums when they realise they won’t be able to something like use this to stream YouTube to their off grid cabin...

Right, I was more thinking a mesh network solar operated to let people report their location and status across rough terrain. I may try making a few of these over the year for next hunting season, and place them in a mile or so radius from basecamp for the duration of my trip, anyways. That way we could split up but still maintain contact, get help if we shoot an elk, etc. We're definitely outside direct walkie-talkie range, and I'm in the only one in the group with a HAM, so this could be pretty useful.

A few points you might be interested in...

The project (mostly) assumes one device per person. Each user carries a tBeam (or one of the other available boards) and Bluetooth connects it to an android phone. The devices mesh with each other, and the phone is used as the interface, with a map view and a messaging view.

Meshtastic automatically sends each nodes location (at a fairly low default update rate, but you can configure that).

There’s a “repeater node” functionality, so a node at base camp or on the highest local terrain can improve the connect ability of the mesh. There’s also a group of people on the forum experimenting with solar power solutions for these nodes, so there’s a fair bit of reported experimental data on solar panel size vs battery capacity vs device runtime (which is all trickier that almost everybody assumes before they’ve tried to do that in real life. “Specs” for solar panels, battery charging controllers, batteries, and even Meshtastic device power consumptions all have way way bigger error bars that most people expects...)

A repeater would have to handle all possible LoRa channels someone might use, right?

Most likely it would have more complex hardware (e.g. something like this: https://www.adafruit.com/product/4284)

I haven't looks deeply into Meshtastic's repeater mode, but it runs on the same hardware as regular nodes. (None of my current personal experimental use cases call for repeaters.)

What I do recall is it can "repeat" encrypted "channels" by just replaying the encrypted packets without having any keys to read them (I think there's some very minor metadata in the unencrypted part of the packets, perhaps just a hop count?)

Also note that "channels" in Meshtastic are not frequencies like in typical UHF terminology - but pre shared encryption keys. I _vaguely_ recall maybe they get used to seed freq hopping algorithms (but I might be misremembering that).

I think the big difference between "repeater nodes" and regular nodes is that the repeater settings shut down the GPS because its unnecessary power draw (on the assumption you know where you installed a repeater node), and participate in the mesh in a "hidden" way, so they don't show up as members you could communicate with.

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