Underground Radio


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:


Underground-to-Surface Communications

        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.


Underground-to-Underground Communications

        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 can help design and build underground sensors for a variety of data collection needs. Examples include:


• Temperature

• Humidity

• Atmospheric Pressure

• Light

• 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:


  • General caving techniques
  • Rope work, vertical ascent/descent methods
  • Underground mapping and surveying
  • Underground lighting techniques and equipment
  • Underground photography/documentation
  • Underground navigation
  • Underground radio communications & telemetry
  • Cave diving
  • Finding hidden or unknown entrances from surface features & geology
  • Development of unattended sensors
  • Development of ruggedized equipment that can survive harsh underground environments
  • Underground rescue and recovery