Patent ID: 8374055

Claim:
A system for locating and communicating with miners in an underground mine, comprising: a battery-powered miner signal unit operable by a miner within the mine and comprising: an impact actuator operative when engaged by the miner with a wall, floor, or ceiling surface of the mine to transmit acoustic signals through the ground, and a user interface having at least one miner-actuatable control to initiate communication via the impact actuator, and an encoder operative to generate an encoded message based at least partially on the at least one miner-actuatable control using seismic modulation and to provide a corresponding modulated signal to the impact actuator; at least three ground-coupled acoustic receivers proximate a ground surface and operative to receive acoustic signals from the ground; and a base station operatively coupled to receive signals sensed by the acoustic receivers, the base station comprising: a decoder operative to decode the signals received by the receivers to determine a message sent by the miner signal unit, a channel equalizer using active time-reversal to process down-link communication to the miner and passive time-reversal to process up-link communication from the acoustic receivers, and a location component operative to determine a location of the miner signal unit based on the signals received by the receivers.