With this in mind, Coal USA has embarked on a survey to simply set out some of the communication products that are available to underground coal operators, including their features, technology, approvals and popularity.
Earlier this year mines were required to have an Emergency Response Plan (ERP) approved that provided for post-accident communications and electronic tracking systems.
The ERP must provide for communication between underground and surface personnel via a wireless two-way medium. The ERP must also include tracking to show the location of any persons trapped underground.
Referenced in the Public Policy Letter were leaky feeders, medium frequency, wireless mesh and wi-fi technologies. Leaky feeder systems function as a power line, communications link and a distributed antenna, while medium frequency radio communications doesn’t require a special cable but a radio signal couples to other existing conductors to increase range.
A mesh system has built-in redundancy where if an access point (node) fails, the system will reconfigure itself and take a new route. Each node requires a power supply and/or back-up battery.
When considering a technology there are some basic areas to address: coverage area, permissibility, standby power capacity, surface facilities, survivability and maintenance.
MSHA has approved the use of page and trolley phones, leaky feeder systems, portable hand-held radios, one-way text messaging system (PED), RFID tracking, and wired and wireless mesh communications and tracking systems.
At time of writing, there were 56 new and modified approval applications currently under MSHA investigation, including 20 RFID components or systems, seven leaky feeder systems, seven peripherals (portable radios, VOIP phones, PDAs, text messaging devices), 13 mesh systems, two medium frequency systems, one through-the-earth system, one inertial navigation tracking system, and five others (page phones, longwall face phones etc). MSHA put through 12 approvals in 2006, 23 in 2007, and 33 in 2008. This year it has approved 44 as of September 18, 2009.
Please click on the pdf document to the right of screen under related links and downloads to view the survey.