Results 241 - 250 of 256

• 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...
• Waveform Generator-Package and Receiver: Mancarried and Helicopter Receiver Portion
  11/1/1974 - Contract reports
  The report describes the design and building of 15 mancarried and 5 helicopter receivers that are used for trapped miner location during a mine disaster. Helicopters are equipped with six-channel receivers and used to detect transmitters carried by mine...
• Research and Development Contract for Coal Mine Communication System: Volume 2 - Mine Visits
  11/1/1974 - Contract reports
  Eight 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.
• Research and Development Contract for Coal Mine Communication System: Volume 1 - Summary and Results of System Study
  11/1/1974 - Contract reports
  Eight 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...
• Research and Development Contract for Coal Mine Communication System: Volume 3 - Theoretical Data Base
  11/1/1974 - Contract reports
  Eight 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...
• Research and Development Contract for Coal Mine Communication System: Volume 4 - Environmental Measurements
  11/1/1974 - Contract reports
  Eight 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.
• Time and Amplitude Statistics for Electromagnetic Noise in Mines
  9/1/1974 - Contract reports
  The time and amplitude statistics necessary to adequately describe electromagnetic (EM) noise in mines are illustrated through computer soft- ware techniques. They are 1) Allan Variance Analyses (AVA), 2) Interpulse Spacing Distributions (ISD), 3) Pulse...
• 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...