Underground Radio Broadcasts New Possibilities
System peers through the earth to allow rescuers to contact personnel in deep mines, buildings and subways
Developed by the Los Alamos National Laboratory and marketed by Vital Alert Technologies Incorporated, the Through-The-Earth communications system allows miners, first responders and other personnel to transmit voice and data through hundreds of feet of rock, concrete, metal and debris.
First responders have historically had great difficulty communicating with each other and with survivors during operations in mines and very large buildings. A radio technology developed by a
The underground radio (UGR) system originated to meet the needs of the
A common feature of these events is the inability of rescuers to coordinate operations properly because of limited communications and an inability to alert workers or other personnel during the event itself. In mine accidents, many workers often do not receive an alert in time to evacuate. In very large mines, personnel are often unable to observe problems early enough to take corrective action. “The same drivers were present 10, 20 and 30 years ago. These accidents are greatly magnified by lack of communication,” Reagor maintains.
Reagor began developing UGR technology in 1996. He shares that in the early days, he worked with a very small budget until the U.S. Energy Department began providing funding in the late 1990s. The technology is built around the small, powerful processors used in cell phones. Modern handheld communications devices use digital signal processors to convert voice communications into bits. “We are using similar technologies developed in the cell phone world—concepts such as digital audio, data compression and radio-on-a-chip,” he says.
These radios on chips are included in small handheld UGR devices. Reagor adds that the opportunity to develop these systems emerged from the revolution in digital processors in the 1980s and 1990s. “We just came in on the end of that [revolution] and applied the results to a product,” he says.
A major difficulty in sending radio signals through earth and rock is that very low frequencies are required. Reagor explains that a typical AM radio station produces signals at one megahertz, or 1 million cycles per second. But the frequencies necessary to pass through dirt and rock must travel at least 30 kilohertz, or 30,000 cycles per second, or less.
The Through-The-Earth Communication system sends very low frequency (VLF) voice signals from the surface to depths of more than 300 feet vertically and through 550 horizontal feet of soil and rock. The radio transmits the signals in the 3- to 30-kilohertz range and uses digital audio compression technology to send wireless voice and data messages.
The VLF system developed by
Reagor says that a typical 900-megahertz radio will send its signals down a tunnel very efficiently, but these high frequency transmissions will not travel through the earth. This is where the Through-The-Earth radio works to connect the surface to the underground world.
Digital compression techniques allowed
The tests demonstrated that radio communications can pass down tunnels and through rock and soil with cell phone type equipment. The UGR equipment transmitted signals from the tunnel, through the surrounding rock to the surface. Reagor explains that once the signal reaches the surface, it can be converted into any other type of radio coverage. The UGR radios also can be deployed in an emergency.
The handsets and radio system are being marketed through a Los Alamos-based commercial firm called Vital Alert Technologies Incorporated. Reagor explains that
Vital Alert is developing and preparing to market several systems based on the Through-The-Earth technology, the Canary 1 and 2 Mine Messenger systems and an emergency broadcast network capability for urban areas. The Canary 2 Mine Messenger System is designed as a pre- and post-emergency warning, evacuation and rescue system for miners that transmits and receives text and two-way digital voice communications. According to Joe Miller, Vital Alert’s president and chief executive officer, the device’s VLF signal cannot be blocked by high density ore, concrete metal, rock, earth, debris or dust.
Miller notes that he had developed an underground emergency notification system for miners in the 1980s, prior to working with
The Canary 1 is a basic pager version of the technology that sends miners text message alerts. The Through-The-Earth pager sends emergency evacuation and operational work-related messages that are displayed on the device’s 32-character liquid crystal display. The entire system consists of one or more transmitters, a wire loop antenna and a computer with proprietary operating software. Miners are alerted to incoming messages via a loud buzzer in the integrated receiver/battery unit and by flashing cap lamps powered by the unit.
The more sophisticated Canary 2 system uses the
Vital Alert is developing an emergency broadcast network capability for use in urban applications such as subway systems, skyscrapers, airports, refineries, power plants, tunnels and large commercial and industrial structures as well as for use by marine and port security.
An emergency broadcasting capability would be especially useful to support operations in large underground mass transit systems, Reagor says. During the terrorist attacks in the
But the UGR technology also is useful for coordinating rescue operations in large structures such as the