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Process and apparatus for detecting the presence of a physical phenomenon

  • US 4,270,041 A
  • Filed: 09/22/1978
  • Issued: 05/26/1981
  • Est. Priority Date: 10/03/1977
  • Status: Expired due to Term
First Claim
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1. An apparatus for the detection of the presence of a physical phenomenon comprising:

  • a sensor sensitive to a characteristic magnitude of the phenomenon to be detected and able to supply a signal representative of said phenomenon;

    at least one amplifier connected to the sensor output;

    means for indicating passing beyond a predetermined threshold significant for the phenomenon to be detected, said means being connected to the amplifier output;

    wherein the means for indicating exceeding the significant threshold comprises;

    a differentiating circuit connected to the amplifier output and supplying a signal which is the derivative relative to time of the signal representing the phenomenon;

    a comparator whose one input is connected to the output of the differentiating circuit and whose other input is raised to a prealert reference potential, said comparator being able to supply a signal for initiating the prealert as soon as the amplitude of the differentiating circuit signal exceeds the amplitude of the reference potential;

    a first time sampling circuit for fixing the elementary prealert periods of duration τ

    as soon as the comparator supplies a first signal for initiating the prealert;

    a second time sampling circuit connected to said first sampling circuit for fixing alert periods of duration T>

    τ and

    a prealert counter having an input connected to an output of the first time sampling circuit and able to count during the alert periods of duration T the number Np of prealert sampling periods during which the reference potential is exceeded;

    alert display means connected to the prealert counter output for indicating the presence of an alert during time T as soon as the number Np of prealerts exceeds a predetermined number Nal, the numbers Np and Nal being whole numbers and the number Nal being selected in such a way that 1<

    Nal <

    T/τ

    .

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