Results 61 - 70 of 74

• Electromagnetic Noise in McElroy Mine
  9/1/1974 - Contract reports
  Two different techniques were used to make measurements of the absolute value of electromagnetic noise in and above an operating coal mine, McElroy Mine, located near Moundsville, West Virginia. The electromagnetic environment created by 300-volt dc and...
• Electromagnetic Noise in Grace Mine
  9/1/1974 - Contract reports
  Two different techniques were used to make measurements of the absolute value of electromagnetic noise in an operating hardrock mine, Grace Mine, located near Morgantown, Pennsylvania.
• Surface Magnetic Field Noise Measurements at Geneva Mine
  9/1/1974 - Contract reports
  Measurements of surface magnetic field noise were made at various locations over the Geneva Coal Mine near Price, Utah, on June 12, 1973. Results of measurements of distant sferics indicate rather sharp cutoff frequencies below which broadband, impulsiv...
• Survey of Electromagnetic and Seismic Noise Related to Mine Rescue Communications: Volume I - Emergency and Operational Mine Communications
  9/1/1974 - Contract reports
  Volume I of this report deals with theoretical, experimental, and practical implementation aspects of the federal Bureau of Mines programs related to present and planned, emergency and operational, mine communications and miner location systems for unde...
• Electromagnetic Noise in Robena No. 4 Coal Mine
  9/1/1974 - Contract reports
  Two different techniques were used to make measurements of the absolute value of electromagnetic noise in an operating coal mine, Robena No. 4, located near Waynesburg, Pennsylvania. One technique measures noise over the entire electromagnetic spectrum ...
• Waveform Generator for (EM) Location of Trapped Miners
  7/14/1974 - Contract reports
  This report describes a circuit for driving a low-frequency loop antenna from a miners cap lamp battery. The circuit is a miniature waveform generator and is part of the electromagnetic (em) trapped miner location system. Two engineering models were des...
• Survey of Electromagnetic and Seismic Noise Related To Mine Rescue Communications: Volume II - Seismic Detection and Location of Isolated Miners
  7/1/1974 - Contract reports
  Volume II of this report (Contract No. H0122026) presents the findings of a short intensive assessment performed during the fall of 1972. This assessment provided the federal Bureau of Mines with independent technical judgments regarding the potentials ...
• Research on the Transmission of Electromagnetic Signals Between Mine Workings and the Surface
  1/10/1974 - Contract reports
  Field studies of ambient electromagnetic noise and electrical transmission properties of coal mine overburdens in Colorado, Illinois, Pennsylvania, and West Virginia were conducted. Field tests of the transmission of low-frequency (20 hz to 20,000 hz) s...
• Proceedings of Thru-The-Earth Electromagnetics Workshop
  12/1/1973 - Conference proceedings, Contract reports
  A need arose to assemble individuals who have been active in current research on the topic of electromagnetic communications systems so that the problem of how information may be conveyed by electromagnetic waves propagating through rock media without t...
• Evaluation and Determination of Sensitivity and Electromagnetic Interactions of Commercial Blasting Caps
  9/1/1973 - Contract reports
  Six different types of blasting caps, mainly of the type used in coal mines, were evaluated to determine both their radio frequency and direct current characteristics.