As a result of a Department of Homeland Security (DHS) SBIR, SRC has developed a bi-directional radio system for voice and data. The technology was developed in response to the needs of Customs and Border Patrol (CBP) agents when entering cross-border and investigating cross-border tunnels. Testing has shown that underground-to-surface and surface-to-underground links can be established with excellent voice communications at extended ranges. Recent testing has shown:
Radio #1 - Located in a 60-foot deep cave
Radio #2 - Located on the surface in mountainous region
Power Level - 5 Watts
Results: More than 4+ km bi-directional communications range.
Radio #1 - Located in a 100-foot deep cave (#1)
Radio #2 - Located in a separate cave (#2) 1,534 feet from Cave #1
Power Level - 5 Watts
Results: SNR of approximately 60 dB.
- Estimated underground-to-underground range > 1 km for deep sites
- > 4 km for shallow tunnels
Survey and Positioning
SRC has several methods to survey underground tunnels, caves and other underground structures. Point positioning uses a stationary beacon underground to create a benchmark or survey point. By locating this point at the surface, it can be geo-located to WGS-84 or other real-world coordinates. We’ve found our horizontal accuracy is better than 0.5% of the depth. For fairly linear tunnels we can map horizontal location and depth of the tunnel within inches in all three coordinate directions.
SRC has demonstrated the ability to track underground personnel from the surface. Our technique used low frequency quasi-static fields as described in Electromagnetic Geophysics. Current status of this technology is manual tracking using rotated surface antennas (Min. 2 measurement points). Future implementations will be completely automated. Tracker range is approximately 500 feet using our proprietary signal processing scheme.
SRC can help design and build underground sensors for a variety of data collection needs. Examples include:
• Atmospheric Pressure
• Movement (infrared)
• Air Flow (speed)
• Sound (audible and ultrasound)
• Pressure Switch (occupation floor mat – mechanical, capacitive, fluid pressure)
• Mechanical Switch (gate open)
• Water Level (mechanical, capacitive, fluid pressure)
• Gas (O2, CO2, CO, flammables)
• Position (tilt sensor)
• Magnetic Heading and Field Strength
• Ground Movement (earthquake or footsteps)
• Strain Gauge (earth movement)
Sandia Research can develop custom underground training courses that specialize in instruction, methodologies and equipment; including: