Results 311 - 320 of 334

• Transmit Antennas for Portable VLF to MF Wireless Mine Communications
  9/1/1977 - Contract reports
  An 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 ...
• Propagation of EM Signals in Underground Mines
  1/1/1977 - Conference papers
  This report is a comprehensive summary of the results of the propagation measurements program conducted for the Bureau of Mines.
• Underground Mine Communications (in Four Parts): 4. Section-to-Place Communications
  1/1/1977 - Information Circulars
  This Bureau of Mines report on underground mine communications addresses methods and equipment to meet the communication requirements of working sections and places of coal and metal-nonmetal mines. A review of the status of trapped miner detection is a...
• Underground Mine Communications (in Four Parts): 2. Paging Systems
  1/1/1977 - Information Circulars
  This Bureau of Mines report summarizes the research, development, and evaluation demonstrations conducted by the Bureau of Mines under the Coal Mine Health and Safety Act of 1969 to improve the means of notifying miners underground, who are away from th...
• U.S. Bureau of Mines New Developments in Mine Communications
  8/1/1976 - Conference papers
  A brief description is given of various Bureau of Mines research activities that have begun since July 1974 and are not being reported on by others at the Third West Virginia University (WW) Conference on Coal Mine Electrotechnology.
• Experience with an Integrated, Computer-Controlled Communications and Monitoring System at the Robena Mine
  8/1/1976 - Conference papers
  A whole mine, computer-controlled communication and monitoring system for both normal and emergency use is installed and operating in the U.S. Steel Robena Mine complex near Uniontown, Pa. Experience with the system is reviewed.
• An Electromagnetic System for Detecting and Locating Trapped Miners
  1/1/1976 - Reports of Investigations
  The theory of electromagnetic fields indicates such fields could be used to detect and locate trapped miners. To be useful, the hardware of the system must meet a number of requirements, including small size, intrinsic safety, and rugged construction. S...
• Technical Services for Mine Communications Research: Task A, Task Order No. 1 - Applicability of State-Of-The-Art Voice Bandwidth Compression Techniques for Wireless Mine Communication
  7/1/1975 - Contract reports
  The 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...
• Technical Bulletin Pager Phones: Installation
  4/1/1975 - Contract reports
  The 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...
• Technical Bulletin Pager Phones: Circuit Protection
  1/1/1975 - Contract reports
  Wires 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...