Technology Open Source

Architecture for
Adversarial Conditions

SafeGround is designed on the assumption that everything will fail. No cellular network. No power grid. No internet. The system must function in the absence of every dependency it would normally rely on.

System Architecture

Three-Tier Mesh Network

The SafeGround architecture distributes intelligence, coverage, and redundancy across three node tiers. Each tier is designed to function independently — and to enhance every other tier when connectivity is available.

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Tier 1 · User Node

Receive & Relay

DeviceLILYGO T-Beam v1.1
RadioSX1276 868 MHz
RangeUp to 5 km LOS
Power18650 battery
Display0.96″ OLED
FunctionReceive, acknowledge, relay alerts
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Tier 2 · Contributor Node

Bridge & Extend

DeviceLILYGO T-Beam Supreme
RadioSX1262 EU868
GPSu-blox M10
RangeUp to 15 km
PowerSolar + battery
FunctionMesh relay, sensor aggregation
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Tier 3 · Admin Hub

Intelligence & Broadcast

ComputeRaspberry Pi 4
GatewayRAK2287 LoRaWAN
AI LayerClaude API (threat assessment)
Data sourcesUSGS, EMSC, Copernicus, Met
UplinkSatellite / ethernet failover
FunctionGenerate, sign, broadcast CAP alerts

ADMIN HUB (T3) ←→ CONTRIBUTOR NODES (T2) ←→ USER NODES (T1) · SELF-HEALING · TDMA SCHEDULED

Admin Hub
⟵ up to 15km ⟶
Contributor Node
⟵ up to 5km ⟶
User Node

Hardware

Purpose-built for field conditions

Every hardware choice in SafeGround is made with one assumption: it will be deployed in a disaster-prone area, by people without specialist technical training, and must continue operating when no support is available.

SENTINEL Core
MCUESP32-S3
LoRaSX1262
GPSu-blox M10
Displaye-ink
Hub Compute
SBCRaspberry Pi 4
GatewayRAK2287
SeismicADXL345
MCUSpark Core

The SENTINEL device is designed to be a grab-and-go unit. In GO mode, it operates entirely on battery, provides GPS beaconing, mesh communication, and displays the last known threat assessment on an e-ink screen readable in full sunlight.

LoRa and embedded electronics hardware components — the building blocks of SafeGround nodes
Embedded hardware: designed for deployment in the world's most demanding environments

Software Stack

Intelligence at the Edge

The SafeGround software architecture runs from bare-metal firmware on field nodes to an AI-driven threat intelligence layer on the Admin Hub — all operating independently of cloud infrastructure.

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AI Threat Intelligence

The Admin Hub runs a Python-based Claude AI agent on the Raspberry Pi 4. Every 15 minutes, it polls USGS, EMSC, Copernicus EFFIS, and local meteorological services, then generates a structured GREEN / AMBER / RED threat assessment using tool_use-based source verification. The assessment is encoded and broadcast to the mesh.

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ATAK Integration

Full integration with Android Team Awareness Kit (ATAK) — the tactical situational awareness platform used by emergency responders and civil defence teams. SafeGround nodes appear as data sources on ATAK maps, providing real-time mesh topology and alert status overlays for responding teams.

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What3Words Integration

Every alert and node registration includes a What3Words location reference. A 3-word address encodes a 3m² square anywhere on Earth — making precise location communication possible for anyone, regardless of technical literacy, in any language, without coordinates.

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CAP v1.2 Alert Format

All SafeGround alerts conform to the Common Alerting Protocol v1.2 — the international standard for emergency alerts. A hexadecimal encoding layer compresses CAP messages for LoRa's low-bandwidth radio link while preserving the full structured alert payload on the receiving end.

Communications Protocols

Designed for duty cycle. Built for encryption.

LoRa networks in Europe operate under EU868 spectrum regulations, imposing strict duty cycle limits that make naive broadcast protocols impractical at scale. SafeGround solves this with a custom TDMA scheduling layer and a hexadecimal alert encoding scheme that reduces message payloads to the minimum necessary for CAP-compliant alerts.

Every message on the SafeGround mesh is end-to-end encrypted using XChaCha20-Poly1305 — a modern, authenticated stream cipher with 192-bit nonces that provides forward secrecy and resistance to nonce-reuse attacks.

Protocol Specification
Radio bandEU868 MHz
MAC protocolCustom TDMA
Duty cycle<1% (EU868 compliant)
EncryptionXChaCha20-Poly1305
Alert formatCAP v1.2 + hex encoding
RoutingGossip + directed mesh
PositioningGPS + What3Words
Tactical layerATAK-compatible CoT
Post-event commsSitRep + Resource Request

Post-Event Communications

SitRep & Resource Coordination

SafeGround is not only a pre-event warning system. The same mesh infrastructure that broadcasts alerts before a disaster provides the communications backbone for structured Situation Report (SitRep) and Resource Request messaging in the immediate aftermath.

Standardised message types enable affected communities to report casualty status, infrastructure damage, and resource needs to Admin Hubs — and for responders to coordinate without relying on cellular or internet connectivity.

Why Not Meshtastic?

Custom TDMA vs Off-the-Shelf Mesh

Meshtastic and similar consumer mesh solutions are effective at small scale. SafeGround targets 30–200 nodes per deployment area. At this scale, Meshtastic's flooding protocol creates unacceptable duty cycle violations under EU868 regulations. SafeGround's custom TDMA layer assigns scheduled transmission windows to each node, enabling reliable EU868-compliant mesh operation at community scale.

Candidate Pilot Site

Pissouri, Cyprus — Visualised Mesh Network

Interactive 3D visualisation of a proposed SafeGround mesh deployment across the Pissouri area — situated on the African-Eurasian plate boundary, with documented landslide risk, growing wildfire exposure, and no existing LoRa infrastructure.

Admin Hub (Tier 3)
Contributor Node (Tier 2)
User Node (Tier 1)
Drag to rotate · Scroll to zoom

PISSOURI BAY, CYPRUS · 34.6627°N 32.7012°E · PROPOSED 30-NODE PILOT DEPLOYMENT · CANDIDATE SITE — NOT YET CONFIRMED

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Landslide Risk

The 2012 Pissouri ground movement displaced 24 families. Over 150 homes remain at ongoing risk. Cyprus Geological Survey monitors the slope continuously. No community warning system exists.

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Wildfire Exposure

The 2021 Arakapas fire destroyed 55,000 hectares and killed four people. Pissouri sits in the expanding wildfire risk corridor of the eastern Mediterranean, with annual fire seasons growing in intensity.

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Seismic Activity

Located on the African-Eurasian plate boundary, Cyprus experiences routine seismic activity. Pissouri's coastal cliffs amplify the landslide risk following seismic events — an ideal multi-hazard PoC environment.