A New York-based company with strong Utah ties said Wednesday that it has developed technology that allows wireless communication throughout a mine, a breakthrough that may help make mining safer.
Global Security and Engineering Solutions, a division of L-3 Communications, said Wednesday that in recent testing for the L-3 Wireless Mesh Mine Communications system, a frequency of 900 megahertz provided a high level of reliable, clear and audible communication throughout all areas of a mine, even around corners deep in a mine. L-3's Communications Systems-West division is based in Salt Lake City and employs 2,300 people in Utah.
The tests were conducted at the International Coal Group's Sentinel Mine in Philippi, W.V., as part of a research and development contract for the National Institute for Occupational Safety and Health.
The testing focused on the system's wireless mesh nodes and found that the 900 megahertz frequency was "the sweet spot on the frequency spectrum," said Dan Erndle, L-3's program manager for the wireless mesh communications system.
The frequency "provides the best propagation distance for communication around corners and around crosscuts," he said.
Miners carry radios that provide them with voice and data communications and give data on the miners' location. The radio signals are transmitted through "fixed mesh nodes" that send the signal to "gateway nodes" that are outside the mine, above ground. A mine operations center, also located above ground, monitors the network and tracks the position of all personnel within the mine.
The signal will always be relayed by the shortest route possible, Erndle said, and automatically adjusts its path.
The system is scalable to any size mine, according to Erndle, with the range on the fixed mesh nodes set to greater than 2,000 feet of radio coverage. He added that in the event of a collapse, the system would automatically detect the communications failure and reconfigure itself to find a working signal to the outside of the mine.
The system must have multiple access points from outside the mine in order to function optimally.
"Typically, our design will include two or more access points to the mine through a bore hole or other opening," Erndle said.
Costs will vary depending on mine size, but Erndle said expenses for L-3's mesh systems should come in at just under $2,000 per node.
Initial development of the system began in May 2007. Final testing is scheduled for this April, with a full-scale demonstration in August. L-3 said the system could be available for use in underground coal mines by spring 2009.
The system is one of two federally funded advanced research and development programs that L-3 has designed to enhance coal mine safety. The second is an ultra wideband-based, real-time location tracking system that would help rescuers more precisely locate miners inside a mine. Both programs are designed to meet requirements outlined in the 2006 federal law known as the MINER Act, which increased safety standards for mines.
This past October, a House committee passed the Supplemental Mine Improvement and New Emergency Response Act, which builds on the initial MINER Act. The measure calls for the government to study better technology for mine communication and tracking systems for miners trapped underground.
L-3's system will be able to integrate with existing wired mine communications systems, Erndle said. Communications systems now used by mines often consist of a cable that emits and receives radio waves. Those systems have a limited range, due to the high frequency signal they require. Higher frequency transmissions cannot pass through solid rock, which limits the systems to a line of sight application similar to an FM radio signal.
L-3's wireless system is not the only mesh technology currently available, but L-3 is unique in its use of transmission nodes. A Canadian firm, Active Control Technology Inc., has also developed wireless technology aimed at improving underground mine safety.
Active Control's system provides two-way wireless voice communications, tracking and data for mines through a wi-fi network. The system has the ability to transport streaming data such as voice and video over multiple wireless feeds.In recent years, coal mine safety has come under intense scrutiny in the wake of numerous fatal incidents. Federal statistics show last year was the second deadliest since 2002 for U.S. coal miners. The Mine Safety and Health Administration (MSHA) reported 32 miners died on the job in 2007, including six miners who were trapped after a collapse at the Crandall Canyon Mine in Utah. Three rescuers died a few days later in an attempt to reach them.