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System for the suppression of noise and its variations for the detection of a pure signal in a measured noisy discrete signal

  • US 4,837,720 A
  • Filed: 03/31/1986
  • Issued: 06/06/1989
  • Est. Priority Date: 04/02/1985
  • Status: Expired due to Fees
First Claim
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1. A system for the suppression of noise and its variations for the detection of a pure signal in a measured discrete noisy signal, comprising:

  • a detector for converting radiation received into electrical pulses;

    a shaping means coupled to the detector for shaping signals produced at an output of the detector;

    an analog-digital converter coupled to said shaping means for converting analog output signals from said shaping means to digital signals;

    a processor means coupled to the analog-digital converter for processing said digital signals; and

    a signaling means for signaling results of processing performed by said processing means;

    said processing means comprising a processor, at least one memory and an input-output circuit;

    wherein the processor sequences the selection of two identical time durations Δ

    t in a selected range of frequential and spatial spectrums of corpuscular radiation, one range where radiating signal is present constituting a signal channel, the other range where there is only noise constituting a reference channel;

    wherein the detector receives the radiation signal from the signal channel having a mean noise level M2 and delivers a first pulse at each detection of radiation signal, each said pulse being transformed and converted by the analog-digital converter and counted by the processor, to produce a sum which constitutes a counting rate N2, wherein N2 gives an estimation of the mean noise level M2, N2 being stored in the memory;

    wherein the detector receives radiation in the reference channel having a mean noise level M3 and delivers a second pulse at each such detection, each said second pulse being transformed and converted by the analog-digital converter and counted by the processor to produce a sum which constitutes a counting rate N3, wherein N3 gives an estimation of the mean noise level M3, N3 being stored in the memory;

    wherein the processor performs the following steps;

    computation of the ratio λ

    E =N3 /N2 which represents an estimation of λ

    defined as the ratio of M3 /M2,computation of the false detection rate TF, according to the following relationships, ##EQU6## computation of a threshold Im where
    
    
    space="preserve" listing-type="equation">I.sub.m =-log (TF/(1-TF));

    computation of the probability of false detection PF according to the following relationships, ##EQU7## computation of a threshold I, where
    
    
    space="preserve" listing-type="equation">I=-log (PF/(1-PF)), andcomparison of I and Im,control of the signaling means as a function of the result of said comparison of I and Im.

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