Drone Geofencing Systems

Introduction

Geofencing creates virtual boundaries restricting drone operations. Critical for airspace safety.

GPS Geofencing

Operation

Compares GPS position against boundaries. Triggers warnings or auto-responses.

Boundary Types

• Circular: center + radius
• Polygonal: multiple vertices
• Altitude ceilings
• Dynamic: time-based

Implementation

Firmware (manufacturer), flight controller (open-source), or external monitoring.

Dynamic Geofencing

TFRs

Temporary Flight Restrictions for events/emergencies. Updates via cellular/satellite.

Real-Time

Subscribes to NOTAM feeds. Updates within minutes.

LAANC

Low Altitude Authorization integrates for compliant ops.

Technical

Position Sources

• GNSS: GPS/GLONASS/Galileo/BeiDou
• RTK: cm-level accuracy
• Visual odometry: backup
• Cellular: urban supplement

Algorithms

Point-in-polygon tests. Ray casting, winding number.

Responses

• Warning: alerts
• Hover: stop at boundary
• RTH: return home
• Forced landing
• Flight prevention

Bypass Methods

GPS Spoofing

False GPS shifts perceived position by km.

Firmware Mod

Modified firmware removes geofencing. DJI jailbroken.

Coordinate Manipulation

Offset calibration shifts readings.

GNSS Jamming

Causes loss of position. May hover/land/continue.

Countermeasures

Multi-Constellation

Multiple GNSS makes spoofing harder.

Anti-Spoofing

Receivers with authentication detect spoofing.

Firmware Signing

Signed firmware prevents mods. Secure boot.

Remote Attestation

Prove firmware integrity before flight.

Regulatory

FAA

Remote ID mandated. Geofencing increasingly required.

EASA

Geo-awareness for certain categories. U-space integration.

Conclusion

Geofencing essential but faces security challenges. Multi-layered protection best.