PLANNING STAGE · v0.1 · NOV 2026

LTAK

A church-run, off-grid disaster communication network. Members scan a QR code on a pocket radio and check in from any phone with no app. Solar repeater nodes relay messages, hold mail, send email out when internet is available, hear voice check-ins over ham radio, and give leaders a live map of who needs help.

The big picture

About 100 pocket nodes and 6–10 repeaters covering about 20 sq mi, with room to grow.

☁ Internet (when available): email + VPN sync Repeater · Zone 1 Raspberry Pi + XIAO (USB) SDR · Solar · LiFePO4 Mailbox · Dashboard · Library Repeater · Main Leader Raspberry Pi + XIAO (USB) SDR · Solar · LiFePO4 Root of trust · Full control LoRa delta sync Pocket Node V1 XIAO S3 + SX1262 · AA Pocket Node V2 Screen + keyboard LoRa 915 Any phoneno app Wi-Fi · QR · captive portal Leaderphone / laptop Handheld radio"KJ7ABC, status green" 2 m voice → SDR → STT + morerepeaters…

What the member sees

Scan the QR code, the page pops up, tap a color. It works the same on iPhone and Android.

LTAK-A7K3🔋 72%

Welcome

Password ••••••••
Sign in
Continue as Guest

Guests type their name. Their check-ins are marked "unverified".

📚 First-Aid Quick Guide

Jane D.📶 Zone 2

How are you?

🟢 GREEN · All OK
🟡 YELLOW · Non-urgent help
🔴 RED · Urgent help NOW
⚫ BLACK · Death occurred
+ choose G / Y / R for survivors
Note (optional, 120 chars)…

📍 ☑ Share location (recommended for non-green)

Jane D.✉ 2 new

Member menu

✉ Mailbox (2)
💬 Message a friend
📧 Send an email
📣 Message leadership

Last check-in: 🟢 14:02 ✓✓ stored at Zone 2 repeater

Hardware

FOR EVERYONE

Pocket Node V1 · about $25–35

  • Seeed XIAO ESP32S3 + Wio-SX1262 (8 MB flash / 8 MB PSRAM)
  • AA lithium batteries, stored separately (rated for about 20 years)
  • Top rocker switch · 3D-printed case
  • QR label plus the printed member login
  • Hosts its own Wi-Fi + web page
OPTIONAL UPGRADE

Pocket Node V2 · Plus

  • Recommended: LilyGo T-Deck Plus
  • Built-in screen, QWERTY keyboard, GPS
  • Type and read without a phone
  • Same chip family, same firmware app layer
  • Rechargeable battery, so it needs a charging plan
CHURCH-PROVIDED

Repeater / Leader Node

  • Raspberry Pi 4/5 on an SSD
  • XIAO kit over USB, driven by a Python bridge
  • RTL-SDR for 2 m (and/or GMRS) voice
  • 100 W solar · 100 Ah LiFePO4 (about 7 days without sun)
  • 3 antennas: LoRa · 2 m · Wi-Fi

Three member kits

Every kit includes four colored window sheets (green, yellow, red, black), a quick-start card and the device. Estimated cost per kit; verify prices before buying.

KIT 1 · BASIC

about $35–51

  • Pocket Node V1 (AA powered)
  • 3 spare lithium AA
  • 4 colored window sheets
  • Instructions + QR/Wi-Fi label
  • No flashlight
KIT 2 · SCREEN

about $97–138

  • LilyGo T-Deck Plus (screen, keyboard, GPS)
  • Flashlight + batteries
  • Spare power for the T-Deck
  • 4 window sheets + instructions
KIT 3 · SCREEN + RADIO

about $129–189

  • Everything in Kit 2
  • Baofeng UV-5R + cable + better antenna
  • Radio check-in card
  • Transmit requires an amateur license

Repeaters (church-provided): Standard (Pi + SDR + 100 W solar) about $610–1,050 · Lite (no SDR) about $420–700 · Relay-only (no Pi) about $150–270. Example system of 100 members and 8 repeaters: about $10,100–16,300. See PLAN.md §14 and FEASIBILITY.md.

Smart routing: not everything goes everywhere

Built on MeshCore's approach: the first message floods to find a route, and later messages reuse the learned path. Repeaters exchange only what the other one is missing.

Message typeGoes toCopied to all leader repeaters?
Check-in (color, GPS, note)Nearest repeater → all leadersYes
Message to leadershipAll leader repeatersYes
Direct message to a friendFriend's node or home mailboxNo (mailbox + 1 backup only)
Outgoing emailAny repeater with internetNo (only until sent)
Admin command (revoke, role change)Everyone, signed by an authorized leaderYes

Routing tiers, cheapest first: internet/VPN → direct LoRa → learned path → flood (last resort).

Receipts: ⏳ Queued✓ Sent✓✓ Stored at mailbox✓✓✓ Delivered👁 Read📧 Emailed✕ Failed (reason)

Chain of care

Status rolls up the tree, and messages can go back down it. Every leader can log in to their repeater's dashboard.

Main Team Leader
root of trust · can revoke nodes
Zone Leader 1
Zone Leader 2
Zone 3
Zone 4
Zone 5
Captain
Captain
Captain
Captain
Captain
× 5 per zone
Member
Member
Member
Member
Member
× 5 per captain

📋 Dashboard

Check-in board sorted Red → Black → Yellow → Green → not checked in. Offline map. Assignments. Supplies. Charts. ICS-211/213/214 exports.

👥 Directory

MRN → name, photo, household, address, callsign, captain. Org chart built automatically.

🛡 Security

Signed, append-only data. A rogue node can't delete anything. The main leader can revoke or quarantine any node.

📚 Library

Kiwix (WikiMed etc.), FEMA, the Army survival manual and first-aid PDFs on the Pi. Pocket nodes hold a small quick guide.

Known risks to test first

⚠ Phone GPS needs HTTPS. Browsers block location on plain http:// pages. The plan is to fall back to the registered home address, offer an HTTPS page with a self-signed certificate (user taps "proceed"), allow pasted coordinates, and offer a GPS module as an add-on. This must be tested on real iPhones and Android phones in Phase 0.

🔋 AA battery life

Wi-Fi uses a lot of power, so Wi-Fi shuts off after 15 minutes and a button press wakes it again.

📡 Range

Do a coverage survey with the existing ping bot (it reports SNR, RSSI and hops).

🎙 Voice accuracy

Vosk with a restricted phonetic-alphabet grammar. Low-confidence results go to a human review queue.

Roadmap

PHASE 0Feasibility tests: portal, GPS, power, range
PHASE 1Pocket node check-in MVP
PHASE 2Repeater + basic dashboard
PHASE 3Messages, mailbox, receipts
PHASE 4Multi-repeater sync + security
PHASE 5Leader tools: map, tasks, supplies
PHASE 6Email gateway
PHASE 7Voice check-in (SDR)
PHASE 8Offline library
PHASE 9V2 Plus handheld
PHASE 10Pilot drill → rollout