The communication uses magnetic field underground communication source technology, and is the world’s first successful attempt at it. Instead of relying on conventional radio waves, which get absorbed almost instantly by rock and soil, ETRI’s system uses low-frequency magnetic fields.
The setup includes a 1-meter-diameter transmitting antenna on the surface and a small, handheld-sized receiving sensor underground operating at around 15 kHz. That’s enough bandwidth to support a data rate of 2 to 4 kbps, which is sufficient for clear, two-way voice communication.
The team successfully tested bidirectional communication between the ground level and the fifth underground layer of a limestone mine, an environment where existing wireless technology cannot reach.
Previous research had only managed a few tens of meters. ETRI pushed that to 100 meters, and the technology is designed to go further.
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