US 5,434,560 AGranted

System for detecting random events

AssigneeDetector Electronics Corporation

InventorsJohn D. King, Richard A. Kevitt

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Abstract

A system for detecting randomly occurring signals, particularly signals representative of a fire condition, having a radiation detector for receiving the signals, peak detector circuits for identifying the peak values of the received signals, peak duration signals for determining the time between adjacent peak signals, and a collection buffer for accumulating values representative of successive peak durations. The peak duration times are compared and evaluated to determine whether regularly occurring patterns of the received signals exist, or whether the received signals are randomly occurring, and an output signal is generated whenever the comparison indicates that the received signals are random in nature.

Claims9

Dependent claims

An apparatus for detecting random signals from a sequence of signals including both random and nonrandom signals, each of said signals having a signal peak occurring at a measurable time of occurrence, comprising:

a) means for identifying the time of occurrence of signal peaks for each signal in said sequence of signals;
b) means for measuring the time between successive identified times of occurrence of said signals;
and means for converting the measured times between signals to logarithmic values, thereby creating successive logarithmic measured times;
c) means for storing the logarithmic measured times in chronological order to form a sequence of logarithmic measured times T.sub.1, T.sub.2, T.sub.3, . . . T.sub.1+n, T.sub.1+2n, . . . T.sub.1+nn, where n is an integer;
d) means, connected to said means for storing, for comparing the respective logarithmic measured times T.sub.1, T.sub.2, T.sub.3, . . . and for generating a 1's output signal when all said compared times are unequal;
e) means, connected to said means for storing, for comparing the respective logarithmic measured times T.sub.1, T.sub.3, T.sub.5, . . . and for generating a 2's output signal when all said compared times are unequal;
f) means, connected to said means for storing, for comparing the respective logarithmic measured times T.sub.1, T.sub.4, T.sub.7, . . . and for generating a 3's output signal when all said compared times are unequal;
g) means, connected to said means for storing, for comparing the respective logarithmic measured times T.sub.1, T.sub.1+n, T.sub.1+2n, T.sub.1+3n, . . . and for generating an n's output signal when all said compared times are unequal;
and
h) means for generating an alarm signal when said 1's output signal and said 2's output signal and said 3's output signal and said n's output signal are all present.

7 more elements

A radiation detection apparatus for detecting randomly occurring successive radiation signals having respective peak values, in a defined field of view, comprising:

a) a radiation detector positioned to monitor said field of view, said detector having means for generating successive electrical signals having peak values responsive to said successive radiation signals' peak values;
b) means for measuring the time between successive ones of said electrical signals' peak values;
thereby creating successive measured times;
c) means for converting said successive measured times to logarithmic values L, and means for chronologically storing respective ones of said logarithmic values in the form L.sub.1, L.sub.2, L.sub.3, . . . ;
where n is an integer;
d) means for selectively subtracting said logarithmic values in groups, wherein adjacent logarithmic values L.sub.1 -L.sub.2, L.sub.2 -L.sub.3, . . . are subtracted to form a first group, second-spaced logarithmic values L.sub.1 -L.sub.3, L.sub.2 -L.sub.4, . . . are subtracted to form a second group, third-spaced logarithmic values L.sub.1 -L.sub.4, L.sub.2 -L.sub.5, . . . are subtracted to form a third group;
e) means for summing the results of said first group of subtractions to form a first sum, and means for summing the results of said second group of subtractions to form a second sum, and means for summing the results of said third group of subtractions to form a third sum;
f) means for comparing each of said respective first, second, third, sums against a predetermined threshold value, and generating an output signal whenever one of said sums exceeds said threshold value;
and
g) means for ANDing said output signals together and generating an alarm signal when all output signals are present.

7 more elements

Dependencies are inferred from the claim text.