Radio communication systems for underground mines

  • US 4,777,652 A
  • Filed: 07/27/1982
  • Issued: 10/11/1988
  • Est. Priority Date: 07/27/1982
  • Status: Expired due to Fees
First Claim
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1. A radio communication system for underground communication, comprising in combination:

  • a transceiver base station including means to transmit intelligence radio signals modulated responsive to audio signals at a first carrier frequency F1 and at a second carrier frequency F2 and to receive intelligence radio signals at the frequency F1, said frequencies F1 and F2 being within the medium frequency range and separated from each other by approximately sixty kHz;

    a base station radio frequency inductive line coupler connected to the base station transceiver, said coupler including an inductive coil for placing about a conductive line extending within a mine and a capacitive member connected to said inductive coil to form a tuned circuit whereby said intelligence signals originating from the base station transceiver may be inductively transferred to said conductive line and carried thereby to remote points within the mine, and signals from within the mine may be carried to the transceiver;

    a first radio frequency cellular repeater located within the mine and coupled to the base station, the repeater including a vertically oriented first tuned loop antenna for transmitting intelligence signals from the base station by radio propagation and a second vertically oriented tuned loop antenna for receiving radio signals from within the mine, said tuned loop antennas being adapted to excite a coal seam propagation mode; and

    at least one mobile transceiver located within the mine and adapted for tuning to said frequency F1, the mobile transceiver including a vertically oriented tuned loop antenna adapted for exciting a coal seam propagation mode, the mobile transceiver being adapted to receive radio propagation signals transmitted by the first radio frequency cellular repeater and by the conductive line and to further transmit radio propagation signals to the repeater and to the conductive line.

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