Until recent times, communication systems in underground coalmines have involved networks of cable or fiber optics. Installation of these systems is usually cumbersome and time consuming, and maintenance is often constant. In emergency situations, the systems have to be shut down; severing all means of communication underground.
In order to alleviate these issues, companies have been introducing new technologies to achieve wireless underground communications; coupled with location tracking. These systems piggy-back on a hard-wire back-bone to transmit data to the surface.
In 2010, Strata Safety Products took underground wireless communications to the next level when it introduced Strata CommTrac. Strata CommTrac is a truly, completely wireless system that does not require any back bone, pre-existing communications system or external power supply. It is the only system of its kind, MSHA approved for underground installation mine-wide.
Operating on a node to node mesh architecture, Strata CommTrac enables communications between miners underground and between miners and surface operators. Two-way text messages are sent and received using a light-weight handheld device carried by each miner. Fixed Communication Nodes installed underground receive and transmit these messages. At the mine entrance a surface transponder interfaces between the networks underground the networks above ground.
“At the surface, the mine can choose to use Wi-Fi, Satellite or hard cabling to transmit data to the server interface,” states company general manager Mike Berube. “But from the entrance, going underground and throughout the mine, Strata CommTrac is one hundred percent wireless.”
The fixed Communication Nodes installed underground are individual, untethered units with no external antennas. They are designed for simple “pick-n-place” installation. This node to node architecture offers excellent redundancy and self-healing capabilities so if there is damage to a node underground, data is automatically and seamlessly re-route to the next nearest receiver.
To achieve tracking, the Miner Communicators emit identification data every 30 seconds. This is received by all Communication Nodes in range. A calculation of the miner’s location is made and plotted on a digital mine map at the surface. Surface operators can track each miner’s location to within 200 ft throughout the mine.
The Communicators are powered by NiMH rechargeable batteries and will operate for over 24 hours. Nodes underground are powered by D-cell alkaline batteries and provide a life span of one year. Battery strength and charge is monitored and reported on the surface user interface.
Since receiving final MSHA approval in November of 2010, Strata Safety has installed twelve complete systems and has 25 additional systems on the schedule for installation before June 15th, 2011.
“We are very excited to see the live success of these systems. One installation in Pennsylvania was fully completed and operational in the span of five hours,” Berube continued.
Strata Products Worldwide, LLC is a global leader in the development and distribution of quality mining and mine safety products and services. With a core competency in roof support, Strata has now become a worldwide leader in emergency refuge chambers, wireless communications and tracking, proximity detection and collision avoidance, mine ventilation and contract services. Headquartered in Atlanta, Georgia, Strata has local support offices in the US, Europe, Australia, South Africa and China.
For more information, please contact Chris Adkins at 304 546-5946 or visit www.strata-safety.com.
Coal News, page 37