A ray of light

Nov 1, 2007 12:00 PM, By Mary Rose Roberts

HAMMONDS' COAL-MINING days are over, but he stays involved by working with the Kentucky Community Technical College System on mine-safety issues, including wireless two-way voice and data communications. His team has developed a man-portable interoperable tactical operations center, or MITOC. The project was funded by a three-year, $1 million grant from the Department of Homeland Security through the state's National Institute of Hometown Security.

MITOC is a system of off-the-shelf, remote-communication devices housed in a suitcase-sized ruggedized case. An embedded BGAN satellite transceiver supports cellular, landline and Internet connectivity for 30 laptops and 36 voice-over-IP (VoIP) telephones. In addition, a radio module supports interoperability by linking disparate radio systems, and a vehicle-mounted VSAT meets higher-bandwidth needs, Hammonds said.

The case can be loaded on a plane, a boat, or a helicopter, or can be shipped commercially. “It can be sent anywhere and then with the flipping of a few switches can be up and operational in less than 15 to 20 minutes,” he said.

Hammonds also uses Rajant Corp.'s BreadCrumbs to set up a wireless-mesh network at an incident. The portable, battery-powered, self-healing 802.11b and 802.11b/g access points are placed at the entrance of the mine to create a wireless LAN. Then, rescue teams responding to an incident transport additional units as they progress into the depths, Hammonds said.

“GPS and GIS won't work underground,” he said. “Everything has to come back through a chain of communications inside to the outside of the mine.”

In addition, as additional access points are dropped, rescuers gain access to streaming data generated by myriad devices. “They will be able to wear sensors on their uniforms that take carbon dioxide [measurements] and will be able to carry a camera that will be able to show live, streaming video from the actual rescue team as they progress forward,” Hammonds said.

The access points pass standard IP traffic that can be carried over several backhaul technologies, said Glenn Booth, vice president of marketing for Rajant. In addition, coal miners can be armed with a mobile unit that attaches to their gear and automatically extends the wireless mesh network, provided it remains within the range of at least one access point, Booth said.

The system was approved in August by the West Virginia Office of Miner's Health, Safety and Training. West Virginia was the first state to implement new mandates after the Sago Mine incident and ordered all of its 202 underground mines to submit wireless-communication safety plans to ensure trapped miners can be located should an accident occur. Booth said Rajant's technology meets the state's mandate that operators must know the location of all miners immediately prior to an event via the use of tracking devices.

Active Control Technology also meets this mandate by providing mine operators with wireless two-way voice communications and a tracking system, said Steve Barrett, president and CEO. The company deploys a Wi-Fi network in a mesh-network configuration that operates on two frequencies. Each mesh node has four radios — two 5.8 GHz radios that provide backhaul connectivity and two 2.4 GHz devices that provide client connectivity. The nodes have a four-day, battery-powered backup system.

“It took 41 hours to find the miners in the Sago mine disaster, so we chose 96 hours as a standard battery backup,” Barrett said.

The signal is propagated through line-of-sight and uses a patented process and methodology to configure the directional antenna and nodes.

“The important thing when you build a mesh network is the range between nodes,” Barrett said. “It's critical that you maximize the range between nodes so you can really control capital costs.”