Results 191 - 200 of 229

• A Short-Range Locator System for Detecting Trapped Miners
  1/1/1984 - Reports of Investigations
  A short-range locator system capable of locating trapped miners has been devised. The system consists of a light-weight, low-power radio transmitter incorporated into a miners cap lamp battery and a directional receiver carried by rescuers.
• Field Test of a Post-Disaster Communication System
  12/1/1983 - Contract reports, Open File Reports
  A new postdisaster communication and location system using through-the-earth electromagnetic wave propagation was tested at the Bureau of Mines Lake Lynn Experimental Mine. This describes the testing process and findings.
• Above-the-Earth Field Contours for a Dipole Buried in a Homogeneous Half-Space
  1/1/1983 - Reports of Investigations
  An essential element of the USBM electromagnetic location and communication system for trapped miners is knowledge of the surface and above-surface electromagnetic fields created by an underground transmitter.
• A Medium Frequency Wireless Communication System For Underground Mines
  1/1/1983 - Contract reports
  An underground medium frequency radio communications system has been developed and demonstrated in both coal and metal/non metal mines. The principal advantage of the system are its low cost, ease of installation and the ability to provide radio communi...
• Theoretical Noise and Propagation Models for Through-the-earth Communication
  9/1/1982 - Contract reports
  A survey of the literature on extremely low-frequency and very low- frequency atmospheric noise was made.
• A Multiplexed Phone System for Small Mines
  7/1/1982 - Conference papers
  A new phone system was developed that provides eight full duplex communications channels over a single twisted shielded phone line, with no central switching station or line amplifiers. This system greatly simplifies installation and maintenance over th...
• Evaluation of the Black River Mine Telecommunication System
  2/1/1982 - Contract reports
  An evaluation was made of one of several improved underground communication systems sponsored by the U.S. Bureau of Mines. The system was installed in a typical metal-nonmetal, room-and-pillar mine and utilized ultrahigh frequency repeaters connected to...
• The Implementation of UHF Radio Communications and CCTV Monitoring Systems in a Room and Pillar Metal/Non-metal Mine
  3/1/1981 - Contract reports
  This report describes the design and implementation of UHF radio and closed-circuit television systems in the Black River room and pillar limestone mine near Butler, Pendleton County, Kentucky.
• Data Security for In-Mine Transmission: Final Report - Part I
  2/1/1981 - Contract reports, Open File Reports
  A survey of electromagnetic noise reports was performed and a summary of the results are given.
• Propagation of EM Signals in Underground Metal/Non-Metal Mines
  1/1/1981 - Contract reports
  This report describes the results of a measurement and analysis program to characterize wireless radio transmission in metal-nonmetal mines over a wide frequency range from 0.2 to 1,000 mhz and over a variety of mine environments.