SAR Team Comms in low coverage zones

Hi, I work with a voluntary Civil Defence team in Spain and want to set up a resilient messaging and tracking network for use in deep valleys and canyons. Typical scenario includes small groups of two or three reporting back to an advanced command post. Current Comms on VHF handsets and GSM IM’s mostly WhatsApp. Later I’d like to be able to send photos for situation update but for the present being able to send SMS from a device with no GSM to an internet connected “repeater” would be great. Further down the line, I’d love to integrate Zello and APRS


What is your question?


I’m preparing a Proof of Concept for a resilient SMS, PNT, WX and image comms system in zero or low coverage GSM/3G/LTE areas.

What would be the best way of constructing such a mesh, and what boards or devices would be best?

Also I’m interested in hearing from anybody with previous LoRa projects in this field as I do not want to reinvent the wheel.

I need to provide intercommunication between small teams in a 100m grid and then onwards to 500m, then via GSM etc to base. The teams operate in a 500m deep valley with base in the next valley, separated by a ridge.

Weather is very hot on summer (>=45°C) with maximum lows on peaks during winter approximately -15°C.



If you’re looking for inspiration and don’t mind doing some lateral thinking, I suggest you also try posting a question in the ATAK subreddit.
It’s not directly LoRa or Meshtastic related (although ATAK does have a nice Meshtastic plugin), but many of the people there are current or former military, with some of them involved in SAR, firefighting and off-grid living, so their user requirements are not very different to yours. I’m sure you will find people there who have done similar projects.

How do I get to the ATAK subreddit?