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- Hazard prevention and control:
- Communications
- Document types:
- Contract reports
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Results 11 - 20 of 21
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6/1/1980 - Contract reportsThe objective of this project was to develop technical data and evaluate performance and utility of leaky feeder communications systems currently used in U.S. underground mines.
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1/1/1978 - Contract reportsThis report covers magnetic field strength measurements versus range and frequency in low to medium coal mines. Both quasi-conductor-free and conductor-proximity areas were investigated.
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9/1/1977 - Contract reportsAn investigation was made of the feasibility of developing compact transmit antennas and/or other means to efficiently couple VLF to MF band radio energy between portable wireless communication units in coal mines. The completely wireless communication ...
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7/1/1975 - Contract reportsThe applicability of voice bandwidth compression techniques to mine wireless communication systems is examined. Promise has been attached to such techniques because the lessened bandwidth gave hope for lessened received noise and hence increased operati...
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4/1/1975 - Contract reportsThe pager phones used in many underground coal mines are battery-operated, party-line telephones with provisions for loudspeaker paging. The system is two-wire, non-polarized, and is operated by self-contained batteries. A description of the many teleph...
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1/1/1975 - Contract reportsWires leading to or from underground facilities can develop hazardous voltages because of lightning exposure. The locations of many mine portals are particularly susceptible to lightning effects. The application of protective devices to limit this poten...
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11/1/1974 - Contract reportsEight coal mines were visited to determine their communications usage and requirements. Volume 2 details the eight mine visits, along with the conclusions reached following each visit and the final conclusions reached.
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11/1/1974 - Contract reportsEight coal mines were visited to determine their communications usage and requirements. Volume 1 summarizes the entire report and includes both a dissertation on the strengths and weaknesses of various available communication techniques and a set of re...
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11/1/1974 - Contract reportsEight coal mines were visited to determine their communications usage and requirements. Available equipment was surveyed and evaluated to determine its applicability to the needs of the mines. Volume 3 contains all information used in predicting the per...
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11/1/1974 - Contract reportsEight coal mines were visited to determine their communications usage and requirements. Volume 4 describes the propagation measurements made in selected mines during the project, along with findings resulting from these measurements.
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Content source: National Institute for Occupational Safety and Health, Mining Program