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A Reader Responds
In the Analog Dialogue Volume 41, Number 2 Editors' Notes, [Scott] wrote:
“The second problem is that the GPS loses its signal when I travel through Boston's Big Dig tunnels, making it unable to maintain its bearings or to provide instructions for lane splits and exits. Too bad it doesn't include an ADI accelerometer, whose inertial navigation capabilities could provide positional information during these temporary signal losses.”
Now, extend that problem to coal mines, where GPS is useless *ALL* of the time. How do you tell a miner’s location *after* an anomalous event like an earthquake, when the mine is literally a different place? Way points might be damaged, so they can’t be relied on. Coal absorbs most radio frequencies, so like GPS, RF is nearly useless.
The physical environment also presents several challenges: dust so thick that you can not see through it; irreplaceable batteries that must be capable of lasting through a 12-hour work shift; intrinsic safety, which requires that the total available energy must not be capable of igniting a methane gas atmosphere; and the need for a small, lightweight device that can be carried for 12 hours.
Some possible areas for research include underground and underwater radio antennas, RFID-Radar, Black Hole antennas, and NIST WWVB radio broadcasts. More information can be found at the Location Challenge and a Technology Review of Smart Sensors with Wireless Networks for Applications in Hazardous Work Environments.
Do any of your readers have an idea that no one has yet thought of?
Bob Paddock [bpaddock@designer-iii.com]
Dan Chimes In
A productive place to start may be with locating tunnels used by escaping convicts, terrorists, and smugglers of dope, other contraband, and people. As a medium for R&D, there are many more of them to be found, and if we can solve that problem, it may be a big step toward locating the (less frequently) lost miners. A solution to this problem could perhaps even allow us to follow miners (and terrorists) around in real time.
The answer is (im?)possibly through gravitational waves, but I don't know of any likely technologies for exploiting them.
Dan Sheingold [dan.sheingold@analog.com]
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