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Child locating and monitoring device

  • US 5,812,056 A
  • Filed: 05/09/1997
  • Issued: 09/22/1998
  • Est. Priority Date: 05/09/1997
  • Status: Expired due to Term
First Claim
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1. A device for providing direct wireless communication between a child and a guardian in an environment while avoiding interference present from other wireless devices operating in the environment, comprising:

  • a guardian monitor for transmitting and receiving wireless signals having frequencies above 900 MHz, said guardian monitor having an address generator for generating a random address and a memory for storing the generated random address, means for setting a first time marker and for communicating a signal comprising said generated random address from said guardian monitor and for detecting every occurrence of said first time marker;

    a child monitor for transmitting and receiving wireless signals having frequencies above 900 MHz for communication with said guardian monitor, said child monitor having means for receiving a signal comprising said random address generated by said guardian monitor and a memory for storing said generated random address, means for detecting every occurrence of said first time marker, means for communicating a signal comprising the received random address back to said guardian monitor upon every occurrence of said first time marker;

    means in said guardian monitor for confirming that the address part of the signal communicated back from said child monitor corresponds to the address part of the signal communicated to said child monitor by said guardian monitor;

    means in said guardian monitor for setting a second time marker that is shifted from said first time marker by a predetermined time period, means for communicating said second time marker from said guardian monitor and for detecting every occurrence of said second time marker;

    means in said child monitor for receiving said second time marker generated by said guardian monitor, means for detecting every occurrence of said second time marker, means for communicating a signal comprising said received random address back to the guardian monitor upon every occurrence of said second time marker;

    each of said child monitor and said guardian monitor further comprising means for storing said generated random address and said first and said second time markers in the memories of said respective monitors upon confirmation by said guardian monitor confirming means that the address communicated back from said child monitor corresponds to the address communicated to said child monitor by said guardian monitor; and

    each of said guardian monitor and said child monitor further comprising means for transmitting wireless signals to and for receiving from the other of said guardian monitor and said child monitor wireless signals incorporating a reference to the stored address so that the one of said guardian monitor and child monitor receiving said wireless signals is operable to compare the incorporated reference and the address stored in said memory of the one of said guardian monitor and child monitor to confirm that the received wireless signal is intended for receipt by said one of the guardian monitor and child monitor.

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