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← Advanced builds · Mission 5 of 30

Text people with no phone signal: build your own LoRa mesh

£25 radios that send encrypted text messages kilometres across hills, festivals and power cuts, with no SIM, no Wi-Fi and no internet. Flash Meshtastic, set up a private channel for your group, and build a solar repeater that runs all winter on a roof. Then bridge the mesh into your own server, so messages from the hills land on your home computer.

210 minAdvancedTools: Two pocket nodes around £50 to £80, solar repeater around £80, software freeStep 1 free
A working mesh of at least two nodes on Meshtastic 2.7.26, paired with your phones, set up for the UK 868MHz band
A private channel with a 256-bit key that only your group can read, shared by QR code
A solar-powered repeater on a roof or mast that extends everyone's range
  • An MQTT bridge into your own broker, plus mesh_bridge.py that logs every message, position and battery report
  • A kit: parts list with UK prices, setup cheatsheet, Mosquitto config and the bridge script with practice data
Before you start
  • Two Meshtastic nodes to start (step 1 picks them). One should be an ESP32 board such as the Heltec V4 for the Wi-Fi bridge in step 6
  • A smartphone with Bluetooth for each person, and Chrome or Edge on a computer for flashing
  • For the bridge: a Raspberry Pi or any always-on Linux box at home. Python 3.9+ for the scripts
  • Basic soldering is optional; everything here can be built with plugs and screws
01/07How the mesh works, and which boards to buy0 done
STEP 01 of 07~20 min

How the mesh works, and which boards to buy

Understand LoRa and mesh relaying, and buy the right three boards for the job.

  1. LoRa is a radio technique that trades speed for range: it sends data very slowly (around a kilobit per second) but can be decoded far below the noise floor, so a 25mW signal can cover kilometres. Meshtastic is open-source firmware that turns cheap LoRa boards into a text-messaging mesh. Each message is encrypted and broadcast; any node that hears it rebroadcasts it (up to 3 hops by default), so a message can leapfrog from your pocket to a roof node to a friend in the next valley.

  2. In the UK it runs licence-free on 868MHzSet every node's region to EU_868 and leave Override Duty Cycle Limit off: the firmware then keeps your power and airtime inside the band's limits on its own.

  3. What to buyMeshtastic supports dozens of boards (device list ↗). Three cover everything in this mission (prices in the parts list):

    • Pocket node: Seeed SenseCAP Card Tracker T1000-E (about £38 at The Pi Hut). Credit-card sized, waterproof to IP65, with GPS and battery built in, and it arrives with Meshtastic already on it. The easiest thing to hand to a family member.
    • Cheap node and home gateway: Heltec WiFi LoRa 32 V4 (about £20 to £30). ESP32-S3 with Wi-Fi and a small screen. Buy the 863-928MHz version. Wi-Fi is what lets it bridge to your home network in step 6.
    • Solar repeater: RAK WisBlock Meshtastic Starter Kit, RAK19007 base + RAK4631 core (29.99 US dollars from RAK, around £30 from UK sellers; choose the 868MHz version). Its nRF52840 chip sips power, and the base board has solar and battery connectors.

  4. Rule of thumbnRF52 boards (RAK, T1000-E, T-Echo) last days on a battery and suit solar; ESP32 boards (Heltec, T-Beam) use more power but have Wi-Fi. Both talk to each other perfectly.

    CarefulNever power a LoRa board without its antenna attached. Transmitting into nothing can damage the radio chip. Screw the antenna on before the USB cable goes in, every time.

  5. Download the kit: parts list, setup cheatsheet, Mosquitto config, and mesh_bridge.py with practice data.

✓
CheckpointYou've ordered at least two nodes (868MHz versions) and know which one will be your home gateway.
If it breaksCan I use a 433MHz or 915MHz board? + 1 more
Can I use a 433MHz or 915MHz board?
In the UK, buy 868MHz versions. 915MHz is the American band and isn't for UK use. 433MHz boards exist but almost every UK mesh is on 868MHz, so you'd be talking to nobody.
Is MeshCore the same thing?
MeshCore is a separate firmware for the same hardware, with a different routing design. The two don't talk to each other. Pick the one your local area uses; Meshtastic has the larger UK community and app ecosystem.
Still stuck? Ask the community
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