US 5,438,321 AGranted

Location system

OwnerHermanus A. Bernard, Francois D. Joubert +1inventors

InventorsHermanus A. Bernard, Francois D. Joubert, Robert D. Crook

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Abstract

A location system for tracking miners underground includes a number of identification stations connected to a central control station. Miners are issued with portable identification modules which are fitted to their caplamps and which are powered by their battery packs. The identification modules transmit unique identification signals at intervals, which are picked up by the identification stations. The identification modules change the intervals between successive transmissions continually, and the identification stations can read overlapping transmissions, so that the reliability of detection is good. Miners who are issued with a caplamp first pass an identification card through a reader, which reads a unique personal identification code from the card. This code is correlated with the identification code of the identification module in the caplamp at the central control station. The invention includes a portable location device for tracking lost miners, which is a direction finding receiver adapted to receive and display the identification code transmitted by the identification module of a lost miner. The identification codes of members of a search party are stored in the device, so that they are ignored in use.

Claims16

Dependent claims

A location system comprising a plurality of portable identification modules, a plurality of identification stations, and a control station, each identification module comprising:

a transmitter;
and
first processor means arranged to store an identification code and to enable the transmitter periodically to transmit an output signal including the identification code, with an interval between the transmission of successive output signals which varies from one transmission to the next;
each identification station comprising:
a receiver for receiving the transmitted identification code from each of the identification modules;
at least one second processor means adapted to identify valid identification codes received by the receiver and to output the identified codes;
and
a communications interface arranged to transmit the identified codes to the control station together with an identification station code corresponding to the respective identification station;
the control station comprising:
third processor means for receiving codes from identification stations and generating a display signal according to the identification modules detected by respective identification stations;
and
display means for providing a display indicating the positions of the identification modules,
wherein at least one of said plurality of identification stations serves as a reporting point and includes a battery charging circuit for charging an identification module and token reading means for reading data from a token identifying a person;
and means for correlating a personal identification code read from the token to the identification code of an identification module being charged with issuing to said person, so that said person's identity can be determined from the identification code of the identification module.

11 more elements

Dependencies are inferred from the claim text.