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Alarm sensor multiplexing

  • US 5,783,989 A
  • Filed: 02/28/1995
  • Issued: 07/21/1998
  • Est. Priority Date: 05/22/1992
  • Status: Expired due to Term
First Claim
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1. A security system for monitoring a protected area and sounding an alarm comprising:

  • at least one sensor arranged about a protected area for sensing incoming threat;

    at least one pulse generator for generating at least one pulse for said sensor activated by said incoming threat to said area;

    an alarm controller for receipt of said pulses and sounding of an alert;

    a single wire connecting output of said pulse generator to said controller for transmission of said pulses to said controller;

    a counter for measuring said pulsewidth of each said pulse;

    said pulse generator generating a first pulse in response to a low level of threat and a second pulse in response to a high level of threat, each said pulse having a different assigned pulsewidth, wherein only said first pulse is generated for communication of said low level of threat received by said sensor, and said first and second pulses are generated for communication of said high level of threat received by said sensor.

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