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Fire detection system using modulation ratiometrics

  • US 5,838,242 A
  • Filed: 10/10/1997
  • Issued: 11/17/1998
  • Est. Priority Date: 10/10/1997
  • Status: Expired due to Term
First Claim
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1. A method of establishing a detected fire condition from a source of incident radiation, said method comprising the steps of:

  • generating a sensor signal from a sensor responsive to incident radiation;

    generating an absolute signal from said sensor signal;

    determining an absolute signal average from said absolute signal;

    generating a flicker signal from said absolute signal;

    determining a flicker value from said flicker signal;

    calculating a modulation ratio from said flicker value and said absolute signal average; and

    providing an indication of a detected fire condition when said absolute signal average exceeds a predetermined threshold value and said modulation ratio is within a selected range of values.

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