GPR Subsurface Detection
Ground Penetrating Radar for underground interference detection.
Technology Overview
GPR Sensor
| Specification | Typical Value |
|---|---|
| Frequency | 250-500 MHz (utility detection) |
| Depth Penetration | 2-5 meters (soil dependent) |
| Resolution | 10-30 cm vertical |
| Swath Width | 1-2 meters |
Detection Principle
GPR sends electromagnetic pulses into the ground and measures reflections:
- Antenna emits radar pulse
- Pulse penetrates ground
- Reflections from buried objects
- Time delay indicates depth
- Amplitude indicates material contrast
Use Case: Underground Interference (#17)
Detecting buried infrastructure before excavation:
Detectable Objects:
- Metallic pipes
- Concrete structures
- Fiber optic conduits
- Underground storage tanks
- Utility cables
Detection Limitations:
- Highly conductive soils reduce penetration
- Water table obscures deeper targets
- Small non-metallic objects challenging
Implementation Approach
Phase 4+ Capability
GPR is technically complex and deferred to later phases:
| Phase | GPR Capability |
|---|---|
| Phase 1-3 | Data collection and visualization |
| Phase 4 | Assisted interpretation |
| Phase 5+ | AI-enhanced detection |
Assisted Interpretation
Initial approach focuses on operator assistance:
- Data visualization: Present GPR data clearly
- Anomaly highlighting: Flag potential objects
- Expert review: Qualified interpretation
- Training data: Build labeled dataset
Future AI Enhancement
Long-term vision for autonomous detection:
- Pattern recognition for common utilities
- Depth estimation from signatures
- Integration with utility maps
- Automated flagging for excavation planning
Operational Considerations
Flight Requirements
| Parameter | Requirement |
|---|---|
| Altitude | Very low (ground contact or <5m) |
| Speed | Slow for data density |
| Coverage | Systematic grid pattern |
| Terrain | Relatively flat required |
Data Volume
GPR generates large datasets:
| Factor | Consideration |
|---|---|
| File size | 10-100 MB per survey |
| Processing | GPU-intensive interpretation |
| Storage | Long-term retention needed |
| Bandwidth | Pre-process before upload |
Multi-Sensor Correlation
| Correlation | Benefit |
|---|---|
| GPR + GPS | Georeferenced subsurface map |
| GPR + Surface Visual | Context for anomalies |
| GPR + Utility Records | Validate known infrastructure |
| GPR + Historical | Change detection |
Risk Acknowledgment
GPR interpretation is technically challenging:
- False positives: Natural soil variations
- Missed detections: Soil conditions vary
- Interpretation skill: Requires expertise
- Validation: Ground truth difficult
Mitigation: Human-in-loop interpretation with AI assistance, not autonomous detection.