SYS//ACTIVE 00:00:00Z
REC UNCLASSIFIED
48.8566N 2.3522E
NAVIGATION SYSTEM

SoOPNav Signals of Opportunity Navigation

GPS-denied positioning using non-navigation RF signals.
When satellites go dark, the spectrum stays lit.

0 Signal Types
<15m Accuracy
0 GPS Required
SIGNAL ACQUISITION

Signal Sources

Cellular

LTE / 5G NR

Timing advance and RSRP measurements from cell towers provide coarse but reliable distance estimates across urban and rural terrain.

Range: 35km Acc: ~200m

WiFi

2.4 / 5 GHz

RSSI fingerprinting against known access point positions. Dense urban environments yield sub-15m positioning with sufficient AP coverage.

Range: 100m Acc: ~15m

Bluetooth LE

2.402-2.48 GHz

Short-range beacon triangulation for indoor and near-field positioning. TX power normalization enables consistent distance estimation.

Range: 50m Acc: ~5m

Meshtastic

868 / 915 MHz LoRa

Mesh radio nodes with known GPS positions relay coordinates. SNR and hop count provide distance bounds for position estimation.

Range: 20km Acc: ~500m

APRS

144.39 / 144.80 MHz

Automatic Packet Reporting System stations broadcast GPS-tagged beacons over VHF. Received signal strength from digipeaters with known positions provides long-range distance estimates.

Range: 100km+ Acc: ~2km

ADS-B (SDR)

1090 MHz

Aircraft transponder broadcasts received via a dedicated SDR tab. Known aircraft positions from ADS-B squitters provide coarse positioning reference points at extended range.

Range: 300km+ Acc: ~5km

FM RDS

87.5-108 MHz

Commercial FM broadcasts carry RDS metadata identifying each station. Known transmitter coordinates combined with received signal strength provide regional positioning bounds across wide rural coverage. CA / UK / US transmitter databases supported currently.

Range: 80km Acc: ~3km

Orbcomm

137-138 MHz VHF

LEO satellite messaging constellation. Public ephemeris from TLE catalogs plus Doppler shift on the downlink carrier yields ranging at orbital scale — useful when terrestrial infrastructure is unavailable. Sub-kilometer precision achievable across multiple passes.

Range: 1500km+ Acc: ~10km

Method

01

Scan

Sweep all available RF bands. Collect RSSI, timing, and metadata from every signal source in range.

02

Correlate

Match observed signals against a reference database of known transmitter positions sourced from 3rd-party and local surveys.

03

Locate

Weighted centroid algorithm fuses all distance estimates into a single position fix, rejecting outliers automatically.

System Specifications

Platform Android 8.0+ (API 26-34)
Language Kotlin / Jetpack Compose
UI Framework Material 3, Dark Tactical Theme
Position Algorithm RSSI-weighted centroid with outlier rejection
Path Loss Model Log-distance with per-signal-type calibration
Reference Data 3rd-party APIs + local survey database
License Proprietary

Download

Android APK available for sideloading. Requires Android 8.0 or later.

Get SoOPNav

About

SoOPNav is a research project exploring GPS-denied positioning through signals of opportunity. By fusing measurements from cellular, WiFi, Bluetooth LE, Meshtastic mesh radios, APRS digipeaters, and ADS-B aircraft transponders (via a dedicated SDR tab), the system provides usable position fixes in environments where satellite navigation is unavailable, jammed, or degraded.

Part of DomainsProject.org — an initiative dedicated to building open datasets and tools for understanding the internet.

Contact