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Article removal alarm system for use with portable electronic device

  • US 5,614,886 A
  • Filed: 10/13/1995
  • Issued: 03/25/1997
  • Est. Priority Date: 10/13/1995
  • Status: Expired due to Term
First Claim
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1. An alarm system for generating an alarm signal upon removal of an article from the vicinity of a base unit, said alarm system comprising:

  • a base unit for generating an ultrasonic signal for transmission into said vicinity of said base unit; and

    a remote unit accompanying said article, said remote unit including;

    a receiver for receiving said ultrasonic signal,a threshold detector for providing a threshold signal upon failure of said receiver to receive said ultrasonic signal at predetermined strength, andmeans for generating an alarm signal in response to said threshold signal.

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