disaster-radio VS ExpressLRS

Also, the messages will be extremely slow. On the low end, 300 baud (if you are close enough, 37kbps, but there are laws preventing full usage in some countries.). Not enough to send pictures in a reasonable amount of time. See also https://disaster.radio/

CollapseOS and disaster.radio?

(btw. no affiliation here, just a happy customer)

Think about using fiber optics at least for longer fixed paths: a couple routers with SFP can provide a gigabit connection over several kilometers, and the fiber cable can be easily buried so that it's not easy to notice and doesn't hint the enemy that a transmitter is operating nearby like WiFi would certainly do.

For very slow and long distance communication, namely text messages, LoRa can be an option to which encryption can be added externally. All other considerations about radio transmission remain valid for LoRa too, however. You may find these links interesting:

https://disaster.radio/

This is extremely cool. Reminds me of https://disaster.radio/

Is anyone currently playing with, or is interested in creating a wireless network in the area to facilitate communication in the event of a disaster? There are these cheap, low power devices (about $20 or less) that can be programmed to communicate with others over very long distances, sending small messages, akin to SMS text message size. I was able to connect to people up to 23 miles away at my last house with this technology (via a Helium miner). The two most popular programs are Disaster.radio (https://disaster.radio/) and Meshtastic (https://meshtastic.org/). You basically put the device in an area where it has decent line-of-sight to someone else's device, and can chat to others via an Android/iPhone app that connects to the radio via bluetooth. This could be useful in general outdoor situations as well, where there is no cell phone service.

Check out https://disaster.radio/. I'd consider a lot of the parts they include in their system:

Just put the firmware builds under https://github.com/ExpressLRS/ExpressLRS/releases

I didn't really find any reference material for setup, you can see it mentioned at #2060 here.

For receiver Zlyden3D said flashing 2.0 then 3 through Betaflight passthrough worked for them.

I think the controller is only going to have PPM output at best. There's a feature request for ppm input marked "not going to happen", so I think you are out of luck. https://github.com/ExpressLRS/ExpressLRS/issues/421

All you need to do is start sending Channels packets out a UART at 115200 baud and the TX will fire up and start sending them at whatever packet rate it is already configured for. You'll need to disable UART inversion on the TX though because external modules are half-duplex inverted (stupid legacy stuff!) The protocol I've documented here: https://github.com/ExpressLRS/ExpressLRS/wiki/CRSF-Protocol