Results 291 - 300 of 329

• 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...
• Performance Evaluation of Electromagnetic Techniques for the Location of Trapped Miners
  1/1/1982 - Reports of Investigations
  The Bureau of Mines (NIOSH Mining) has conducted field studies in coal mines throughout the United States to determine the effectiveness of electromagnetic techniques in locating miners trapped underground following a mine accident.
• A Communication and Monitoring System for an Underground Coal Mine, Iron Ore Mine, and Deep Underground Silver Mine
  11/1/1981 - Contract reports, Open File Reports
  Advanced communication and monitoring systems were developed and demonstrated in three underground mines representing different mining techniques, geographical areas, and material mined.
• 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.
• Development of a Visual Display and Control System
  10/1/1980 - Contract reports
  The object of this program was to extend the capabilities of visual paging systems both in size and functions in mines. The system developed uses the mine pager phone line for communication, monitoring, and remote control. The system was designed to be ...
• Detection of Trapped Miner Electromagnetic Signals Above Coal Mines
  7/1/1980 - Contract reports
  This report assesses the expected detectability, on the surface above mines, of electromagnetic signals produced in the 630- to 3,030-hz frequency band by a rescue transmitter activated by miners trapped underground. The implications of the results and ...