Published today

New technology in mine communications Pt. 2

By PATSY STODDARD
Editor

Oneof the sessions for the Utah Coal Mine Safety Conference held recentlyconcerned new technology for underground communication with thesurface. Marshall Radio Telemetry is a company based in Salt Lake City.They are dedicated to the design and production of premium telemetryequipment for tracking and communication.

Kevin Harcourt spoke to the audience at the conference. Hesaid their radio tracking system was used to locate a hunting dogwearing a radio tracking collar, that went into a cave and never cameout. Using a hand held telemetry receiver, the dog's owner was able toexactly pinpoint the dog's location from above ground. After three daysof digging and the help of a drilling rig, rescuers punched through therock and rescued the dog. Their tracking systems have also been used tokeep track of wandering boy scouts on wilderness camps.

Recently a research team from Marshall has been in Carbon,Emery and Sevier counties testing their equipment. They have visitedConsol, Dugout, Westridge, Bear Canyon and Skyline mines.

In the aftermath of the Crandall Canyon mine disaster,MSHA has mandated mining companies to install equipment for trackingand communicating through the earth with coal miners. The problem hasbeen the technology hasn't been there to do what MSHA has requested.

David Marshall said they had a great time visiting thecoal mines in the area. He couldn't believe the darkness of the minesand he commented, "You must feel like you are leaving all communicationbehind when you enter the coal mine. With our technology, we hope tobring that communication back. He said it is a myth that radio waveswill not travel through rock. They travel shorter distances undergroundthan they would through the air, but they always can penetrate somedistance. Marshall said they have met with success in their testing andhave achieved two-way voice communications through thousands of feet ofrock in Utah mines. "This is a breakthrough. We have spent 10 yearsworking on equipment small in size but powerful enough to send radiowaves long distances," Marshall said. "Our very small (10 grams) radiotransmitters are capable of sending a signal 360 miles and yet are ableto transmit a signal for up to two weeks. But, it's not an ordinaryradio system. Marshall mentioned that above ground the system has beenused with tracking falcons. NASA has even called Marshall RadioTelemetry to ask if their system could be used to track equipment onthe moon or Mars.

Currently the military is buying their tracking devices totrack their unmanned aerial vehicles. Marshall Radio has its trackingequipment currently in use worldwide, including Afghanistan and Iraq.

Marshall said he has been interested in radiocommunication since he was a child. He became a HAM radio operator atage 14. He said radio waves can go through almost anything, but metaland salt water. "With a lower frequency it's easier to go through solidmaterial. We go down in frequency until the radio signal gets through.There were experiments in 1922 and they said it's not possible forsignal to pass through solid rock. I have done extensive research ontheir findings and other reports. While searching the internet I foundmore than 300 papers written on the subject which I have reviewed.Currently there are more than 80 companies interested in thistechnology and working on it," said Marshall.

Marshall explained frequencies and said a normal radiocommunications frequency would be a million or more vibrations persecond. A cell phone operates between 800-1,900 million vibrations persecond. In the mining world, the vibrations need to be reduced frommillions to thousands of vibrations per second or less, which is reallyslow, but in this manner the sound of a human voice can be transmitteddown into the earth, as well as from inside the earth to the surface."As a result of these tests we've conducted, we know we can go down tothe depths required by coal mines," said Marshall.

Marshall said the human ear will be able to pick up thesesounds. He said there is no limit on how low in frequency you can goand how far you can penetrate the earth with these kinds of radiowaves. He said there are several problems with such low frequencies.One is that there is a lot of noise underground, it is difficult to getthe signal through with all the interference. Nature itself is noisyand there are atmospheric disturbances when broadcasting on such a lowfrequency. At low frequencies, disturbances from lightning dischargeseven become a problem. "You can hear lightning strikes from thousandsof miles away," said Marshall.

"There are some difficult challenges as you go to lowerand lower frequencies. The challenge is to be able to put informationon the radio signal. To transmit a human voice you need a band widthbetween 400-3,000 cycles per second. The voice is still understandableat 2,000 cycles per second. Any lower than that and the words becomeindistinguishable. So the question is how do you convey a voice on asignal that is lower in frequency than the voices own frequency? Youcan take a single radio wave and put in a certain amount of modulationand you can convey information. Like, Morse code, there is a limit tohow much information you can pack into one signal. You can try tocommunicate non-vocal information. Like, having a coded signal thatmeans 'I'm alive.' But, As you go deeper and decrease the cycles persecond, then the ability to send many such coded messages or text orvoice information continues to go down. And, the abilitiy to decipherthe information also diminishes," said Marshall.

Marshall explained an existing magnetic wave system thatgoes through the earth, but the information is so slow and it takesminutes to transport a simple message. These are the problems that theindustry has faced. "But, to the extent that you can separate thesignal from all the noise you can pick up signals further underground.

"We use powerful microchips with a special kind of newsignal processing software to achieve this goal. To separate the noisefrom the signal underground, and then reconstruct the voice, requiresbillions of calculations per second. This is what enables ourtechnology to transmit fast information including voice or digitalsignals and still be able to dig them out of the horrendous noise deepwithin the earth," said Marshall.

"Life is without price. We got into the business to see ifthere was anything we could do to help. We have tested our product incaves and we went into the silver mine tunnels in Park City.

"At the first coal mine test at Consol mine near Emery, wehad two way communication from the surface to the coal seam at a depthof 400 feet. In the Dugout mine we had communication to a depth of5,800 feet from outside the mine into the mine along the coal seam.Transportation of signal has to do with the nature of the materialsalso, the dryer the material the easier it is to transmit the signal.We tested at West Ridge, Skyline and Bear Canyon. In one of ourexperiments, at the Bear Canyon Mine, at a depth of 1,400 feet wepicked up a signal, from the surface to the coal seam. The radio signalwas strong and at that depth we could have sent a voice.

"We have been researching and now we are ready to move tothe next step. Our belief is that we can build a practical two-waycommunication system today which will work at depths not more than2,000 feet. It already does work. We would set up base stations in themine. A small amount of equipment would be contained within a box. Weplan later to have a mobile system that can be moved as workers movewithin the mine or with mine vehicles. A hand-held system, similar to awalkie-talkie is also being considered," said Marshall.

Marshall questioned the mine companies present and askedif they developed such a system would the companies be interested init.

The question was asked as to where the undergroundequipment has to be in relation to the equipment above ground. Marshallsaid for a depth of 1,000 feet then the radio on the surface area wouldneed to be in the 5,000 foot range. Marshall said some companies haveasked if the system could be used for day to day communication.Marshall said it is less practical as a day to day system. For day today use, they believe they can create a horizontal system, that wouldtransmit along a coal seam for miles as well as vertically. Whentransmitting horizontally, the radio signals go straight through thecoal pillars and solid rock and coal rather than going through the airdown tunnel as some other short range systems do.

The question was asked about tracking devices for miners.Marshall said with a tracking device worn by a miner they can get apretty good idea of where the miner is in the mine, but it won't give apinpoint location. But it is possible to tie in with other systemsalready on the market today which read computer chips as a miner walksby a certain location and you can tell when a miner has passed into acertain area of the mine. Such information can be relayed to thesurface with the Marshall system.

Currently none of the technology available for mines istruly through the earth (wireless). MSHA has mandated wireless systemsfor the mines, but these products aren't on the market yet, or if theyare they do not provide two way voice communication after an emergencyas required by the requlations. Marshall was asked about the cost oftheir system. He said the cost hasn't been determined yet, but heexpects it will be cheaper than some of the systems out there today.Marshall said he doesn't know yet, when their product will beavailable, but expect a system for use in coal mines to be ready withinthe next two years.

The mining companies said they are very interested in theproduct. Their problem is they are being mandated to have thisequipment in their mines, but this two way communication isn'tavailable yet. When new regulations came out on June 15 the mines wereinstructed to have this type of equipment. If the new system could bedeveloped within a year, the mines could put it to use if not they arebeing required to have something in place.

One mining official said, "MSHA is putting the heat on mines to get a system."

Itwas mentioned that Congressman Matheson helped pass legislation torequire better communications at mines. It was wondered whether hecould be contacted to slow this down, until the wireless equipment isavailable. MSHA is being instructed by Congress to move ahead withcommunication systems for mines.

Garth Nielsen, is the director of the Office of Coal MineSafety and he closed the conference by asking miners and companies touse the technology as it becomes available. "Use your minds and try tocome up with new things to help keep our miners safer," said Nielsen.


Source: http://www.ecprogress.com/index.php?tier=1&article_id=8325