SafeTag · Off-grid rescue beacon

A rescue beacon for where the network ends

SafeTag sends an SOS with your coordinates over LoRa radio to towers and drone relays. No cellular coverage needed, no satellite subscription.

Request a pilot How it works
5–15 km
ground range to a gateway
up to 30 km
to an airborne gateway
97%
of packets delivered through a drone relay
1–3 years
on standby from 500 mAh, phone-assisted

Figures from our research and field tests

Why

When coverage ends, time works against you

In a dead zone a phone cannot call for help, and rescuers have no position to start from. Every hour of delay widens the search area by square kilometres.

65% of Carpathian ridges
are dead zones with no mobile coverage.
300+ rescue operations
are run in the Carpathians every year.
$300–600 per device
plus a subscription, is what satellite messengers cost.
How it works

From one button to a dispatched team

Hiker with SafeTag
One press sends an SOS with coordinates taken from the phone over Bluetooth or from built-in GPS.
Tower and drone gateways
Towers on the ridges can run on solar power; drone relays cover the blind spots between them.
Shared ledger
The SOS, its position and time are hashed and replicated between rescue centres.
Rescue coordination
A smart contract alerts the nearest unit; every service sees the same verified position.
The tag

Clips to a backpack, waits for years

The beacon sleeps until it is needed. Where its position comes from decides how long the battery lasts, so SafeTag supports both ways.

Longest battery
Phone-assisted
Coordinates arrive from the phone over Bluetooth Low Energy; the tag saves its charge for the SOS.
Active current
5–7.5 mA
Sleep current
under 1 µA
Standby, 500 mAh
1–3 years
Cost to the phone
1–3% a day
No phone needed
Built-in GPS
The tag finds its own position and works with no other device nearby.
Active current
23–40 mA
Power-save current
about 5 mA
Runtime, 500 mAh
12–20 hours
Under dense canopy
fix can be lost
3D illustration · move the pointer to turn it
Radio

LoRa carries on where 2.4 GHz stops

Wi-Fi and Bluetooth fade in the first stand of trees. LoRa's chirp modulation is decoded below the noise floor, so the signal survives terrain, foliage and mountain echoes.

In dense forest at ground level we measured 250 m at SF7 and 500–800 m at SF12. That is why the network pairs towers with drones.

Bands
433 / 868 / 915 MHz
Licence-free ISM spectrum
Range
5–15 km, up to 30 km airborne
Large areas from few gateways
Sensitivity
down to −148 dBm at SF12
A link even without line of sight
Adaptive rate
SF7 to SF12
Speed traded for reach when the valley demands it
Error correction
works at −20 dB signal-to-noise
Forward error correction built in
Topology
Star of stars
No mesh routing on the tag
Field results

A drone overhead changes the link

One beacon, 1.3 km away behind hills and forest, received two ways: by a gateway on the ground and by a drone at 100 m.

Packets delivered
Ground gateway27%
Drone at 100 m97%

On the ground only every fourth packet got through. With line of sight from the air, almost all of them did.

MetricGroundDroneChange
Signal strength (RSSI) −113 dBm −93 dBm +20 dB
Signal to noise (SNR) −16 dB −2 dB +14 dB
Packets lost 73% 3% −70 points
Packets delivered (PDR) 27% 97% +70 points

The network holds as it fills

Long-range settings occupy the air longer, so adaptive data rate keeps each tag on the fastest setting that still reaches a gateway and saves SF12 for emergencies.

Relay drones need a ground station: see AirCruise GCS

Devices on airDelivered, SF7Delivered, SF12
50 99.1% 96.5%
200 94.2% 82.3%
500 88.5% 71.0%
Ledger

A record nobody can rewrite

Rescue brings state services, volunteers and private teams together. A permissioned ledger on Hyperledger Fabric gives all of them one verified account of what happened, where and when.

No single point of failure
Every tower and drone gateway holds the record, so an SOS survives a lost server or a power cut.
Fixed place and time
Coordinates and timestamps are hashed into the chain the moment they arrive and cannot be altered later.
Dispatch by smart contract
When independent gateways confirm the same SOS, the contract alerts the nearest unit and reserves a relay drone.
Shared, not exposed
Police, medics and rangers read the same data; cryptographic keys decide who sees what about the person.
  • 1.2–2.5 s from gateway to ledger in tests
  • Photos stored on IPFS
  • 30% of nodes down: access only 15% slower
Beyond rescue
The same network, other jobs
  • Forest fire monitoring
  • Sensors across farmland
  • Coordination in disaster zones
Roadmap
What we are working towards
  • A bridge to low-orbit satellites for worldwide reach
  • On-board AI that steers the search drone
  • Pulse and oxygen sensors to set the priority of a call
  • Post-quantum cryptography for the ledger
Pilot

Run a SafeTag pilot in your region

For rescue services, national parks and trail operators. Tell us about the terrain and we will plan the gateways with you.