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Personnel monitoring and locating system

  • US 4,495,496 A
  • Filed: 12/15/1981
  • Issued: 01/22/1985
  • Est. Priority Date: 12/15/1981
  • Status: Expired due to Fees
First Claim
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1. A system for monitoring a plurality of movable objects within a preselected area, said system comprising:

  • a plurality of transmitting means at said preselected area;

    control means connected with said plurality of transmitting means to cause each of said plurality of transmitting means to provide an interrogation pulse output at predetermined times;

    a plurality of transponder means each of which is associated with and constrained to movement with a different one of said movable objects, with said plurality of transponder means being capable of simultaneously receiving said interrogation pulse output from said plurality of transmitting means, and with each of said transponder means, responsive to receipt of said interrogation pulse output from said transmitting means, providing a reply output with said reply output from each of said transponder means being delayed by different predetermined time intervals so that all reply outputs from said transponder means occur at different time intervals with respect to one another; and

    signal processing means for providing an output indicative of the particular transponder means from which a reply output was received to thereby enable monitoring of the objects associated with said transponder means.

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