ETRI Achieves World-First Demonstration in Limestone Ground… Expected to Enhance Disaster Rescue and Military Operations
A domestic research team has achieved the world’s first successful demonstration of wireless voice communication underground. They accomplished two-way voice communication over a 100-meter distance in limestone ground where conventional radio waves nearly fail to reach. This breakthrough could vastly improve communication in high-risk scenarios like mine collapses or underground military operations, where the danger of “communication disruption” is substantial.
The Electronics and Telecommunications Research Institute (ETRI) announced on the 13th that they have successfully tested a “subsurface communication core technology” using low-frequency magnetic fields. The research team established a straight-line, approximately 100m-long connection between two points, above and below ground, to send and receive voice signals. This achievement significantly surpasses prior international research findings, which were limited to several tens of meters.
In underground environments, radio waves weaken significantly, making it almost impossible to use conventional wireless communication devices. Limestone rock, in particular, is known for severe signal attenuation, rendering communication virtually impossible. In response, ETRI developed a method utilizing “magnetic fields” instead of radio waves. Magnetic fields transmit stably through underground media, allowing for voice communication at speeds of 2-4 kbps using ultra-low frequencies (around 15 kHz).
The research team built a system combining a 1m diameter transmitting antenna with small receiving sensors just a few centimeters in size. They successfully demonstrated the system’s functionality by transmitting voice signals in an underground mine environment.
This technology holds significant potential for application in various fields, such as search and rescue during mine collapses, safety management of buried infrastructure like underground utility vaults, gas pipelines, and oil pipelines, and secure communication in military underground operations.
ETRI is also working on expanding this technology to integrate with personal devices like smartphones, aiming to broaden the communication range by developing a system that serves as a relay between ground and subsurface. The research was published in the IEEE IoT Journal and has secured numerous patents globally for core technologies like transmitters, antennas, and low-frequency modems.
As of now, ETRI has accumulated expertise through 12 SCI papers and 8 international patents. Jo In-gwi, an ETRI principal researcher, stated, “We have proven the possibility of voice communication in extreme underground environments where traditional radios fail, potentially revolutionizing the safety and efficiency of mine rescue operations.” In addition, Park Seung-geun, head of the Radio Research Division, emphasized that “this technology will greatly benefit various industries such as underground facilities, tunnels, and marine drilling, providing a highly reliable communication means for extreme environments.”
This technology development was supported by the Ministry of Science and ICT and the IITP under the “Micro-Magnetic Field Based Mid to Long Range Magnetic Field Communication Technology” research project, with private companies Admotec Co., Ltd. and DoIT participating in the testing process.