HOW DO WIRELESS NETWORKS WORK? Wireless networks use radio waves to transmit information. In walkie-talkies, sound waves are converted into an electrical current, and the encoded sound data hitches a ride on a radio wave. It does this by changing either the wave's height or its frequency, which is the number of times the wave curves up-and-down per second. Think of the unmodulated radio wave as a blank sheet of white paper, and the encoded sound wave as the ink that forms the printed words. The ink causes variations against the background of the paper, and this is what the eye sees when it "reads." Radio uses noise instead of paper and ink. Unmodulated radio waves will have the same height or frequency. Mixing in a data stream of electrons causes slight changes in either of those two properties. These changes are detected by a receiver, which then decodes the information.
HOW INSET WORKS: Different location tracking technology rely on many different components, including geographic information systems, global positioning systems (GPS), wireless local area networks, and the infrastructure that has evolved around cellular phones and personal data assistants (PDAs). The mining system features transmitters with GPS capability and inertial motion sensors which send signals out. The transceivers bolted to the roof of the mine detect the signal, and relay positions to a central computer outside of the mine, which tracks and plots the position of each miner. The system also uses an algorithm to help correct for a problem called drift which occurs when small inaccuracies in the motion sensor add up over time.
The American Industrial Hygiene Association and the American Society of Civil Engineers contributed to the information contained in the TV portion of this report.