Signal recognition and classification for identifying a fire

• US 5,237,512 A
• Filed: 11/20/1991
• Issued: 08/17/1993
• Est. Priority Date: 12/02/1988
• Status: Expired due to Term

• Current Assignee: Detector Electronics Corporation (Carrier Global Corporation)
• Original Assignee: Detector Electronics Corporation (Carrier Global Corporation)
• Inventors: Davidson, Ian
• Primary Examiner(s): Black, Thomas G.
• Assistant Examiner(s): ZANELLI, MICHAEL J
• Application Number:
  US07/798,040
• Time in Patent Office: 636 Days
• Field of Search: 364/487, 364/550, 364/505, 364/570, 382/22, 382/1, 340/577, 340/578
• US Class Current: 702/73
• CPC Class Codes: G06V 10/40 Extraction of image or video features
• CPC Class Codes: G08B 17/12 Actuation by presence of radiation or particles, e.g. of infrared radiation or of ions

Abstract

An apparatus and method for sensing electro-magnetic radiation and analysing the resultant electrical signal waveform, in order to determine whether the radiation originates from a fire condition, monitors variations in the signal waveform over a predetermined period of time. The amplitudes of the successive transitions in the waveform and the elapsed time between the transitions are measured. Two two-dimensional matrices are produced. The first of these is made up of a plurality of co-ordinate points each corresponding to a respective pair of successively occurring signal transitions. The position of each such point in the matrix is dependent on the respective amplitudes of the two transitions making up each pair. The second matrix is also made up of a plurality of co-ordinate points each corresponding to a respective pair of the signal transitions. In the second matrix, however, the position of each point within the matrix depends on the amplitude excursion and the elapsed time between the two transitions of each pair. The matrices thus produced are compared with predetermined matrices corresponding, for example, to predetermined fire conditions or false alarm conditions, whereby to determine whether the sensed radiation has a pattern corresponding to a fire or a false alarm situation.

Claims

1. Apparatus for the recognition and classification of electromagnetic radiation from a source, for detecting whether the source is a fire comprising sensor means responsive to the electromagnetic radiation for producing an electrical signal waveform in dependence on the electromagnetic radiation, means for detecting and measuring values relating to any successive amplitude transitions of the electrical signal waveform during a predetermined period of time, means responsive to the means for detecting and measuring, for generating a two-dimensional signal amplitude matrix made up of a plurality of co-ordinate points each dependent on the measured values relating to a respective pair of successively occurring said amplitude transitions and each of whose positions within the matrix is dependent on those measured values, means for prestoring at least one predetermined signal amplitude matrix representative of electromagnetic radiation from a known source, means for comparing such generated matrix with said at least one predetermined signal amplitude matrix for classifying the electromagnetic radiation producing the electrical signal waveform from which the matrix has been generated, and alarm means responsive to said means for comparing, for generating an alarm when said means for comparing classifies the electromagnetic radiation as electromagnetic radiation from a source of fire.

2. Apparatus for the recognition and classification of electromagnetic radiation from a source, for detecting whether the source is a fire, comprising sensor means responsive to the electromagnetic radiation for producing an electrical signal waveform in dependence on the electromagnetic radiation, means operative to detect any successive amplitude transitions of the electrical signal waveform during a predetermined period of time and to measure the amplitude change of the electrical signal waveform between successive amplitude transitions and the time separation between successive amplitude transitions, means responsive to the measured amplitude changes and the measured time separations for generating a two-dimensional signal amplitude matrix made up of a plurality of co-ordinate points each corresponding to a respective pair of successively occurring said amplitude transitions and each of whose positions within the matrix is dependent on the respective measured amplitude change and measured time separation between the two amplitude transitions in the pair, means for prestoring at least one predetermined two-dimensional signal amplitude matrix, means for comparing such generated matrix with said at least one predetermined two-dimensional signal amplitude matrix for classifying the electromagnetic radiation producing the electrical signal waveform from which the generated matrix has been generated, and means responsive to said means for comparing, for signaling an alarm when said means for comparing classifies the electromagnetic radiation as electromagnetic radiation from a fire source.

3. A method for the recognition and classification of electromagnetic radiation from a source, for detecting whether the source is a fire, comprising the steps of sensing the electromagnetic radiation to produce an electrical signal waveform in dependence on the electromagnetic radiation, detecting any successive amplitude transitions of the electrical signal waveform during a predetermined period of time and measuring the amplitude values of the electrical signal waveform at each of the transitions, generating a two-dimensional signal amplitude matrix made up of a plurality of co-ordinate points each corresponding to a respective pair of successively occurring amplitude transitions and each of whose positions within the matrix is dependent on the respective measured amplitude values of the two transitions in the pair, constructing at least one predetermined two-dimensional signal amplitude matrix representative of a signal waveform from a known condition of fire, comparing such generated matrix with said at least one predetermined matrix for classifying the electromagnetic radiation producing the electrical signal waveform from which the generated matrix has been generated, and indicating an alarm when the classified electromagnetic radiation is indicative of a fire.

4. A method for the recognition and classification of electromagnetic radiation from a source, for detecting whether the source is a fire, comprising the steps of sensing the electromagnetic radiation to produce an electrical signal waveform in dependence on the electromagnetic radiation, detecting any successive amplitude transitions of the electrical signal waveform during a predetermined period of time and measuring the amplitude change of the electrical signal waveform between successive amplitude transitions and measuring the time separation between successive amplitude transitions, generating a two-dimensional signal amplitude matrix made up of a plurality of co-ordinate points each corresponding to a respective pair of successively occurring amplitude transitions and each of whose positions within the matrix is dependent on the respective measured amplitude change and measured time separation between the two amplitude transitions in the pair, constructing at least one predetermined two-dimensional signal amplitude matrix representative of a signal waveform from a known condition of fire, comparing such generated matrix with said at least one predetermined matrix for classifying the electromagnetic radiation producing the electrical signal waveform from which the matrix has been generated, and generating an alarm when the classified electromagnetic radiation is indicative of a fire.

5. Apparatus for detecting whether a source of electromagnetic radiation is a fire, comprising sensor means responsive to the electromagnetic radiation from the source to produce an electrical signal waveform varying in amplitude in dependence on the variation of the detected electromagnetic radiation, waveform transition detecting means connected to receive the electrical signal waveform and operative to detect any successive transitions of the electrical signal waveform and to measure the amplitude value of the electrical signal waveform at each such transition, first recording means operative to record the change in amplitude value between each transition and the next succeeding transition for storing a first set of amplitude changes corresponding to a predetermined time portion of the electrical signal waveform, second recording means operative to store at least one predetermined, second, set of amplitude changes between the successive transitions of an electrical signal waveform corresponding to the variations of electromagnetic radiation derived from a predetermined source of electromagnetic radiation, comparing means operative to compare the first stored set of amplitude changes with the said at least one second stored set of amplitude changes, and output means responsive to the comparison carried out by the comparing means to determine whether the source sensed by the sensing means is a fire and to produce an output indication accordingly.

6. Apparatus according to claim 5, in which the first recording means comprises means recording, for each pair of succeeding transitions in the electrical signal waveform produced by the sensor means, the value of the signal amplitude at the first of each pair of transitions and the value of the signal amplitude at the second transition of the pair.

7. Apparatus for detecting whether a source of electromagnetic radiation is a fire, comprising sensor means responsive to the electromagnetic radiation from the source to produce an electrical signal waveform varying in amplitude in dependence on the variation of the detected electromagnetic radiation, waveform transition detecting means connected to receive the electrical signal waveform and operative to detect any successive transitions of the electrical signal waveform and to measure the amplitude value of the electrical signal waveform at each such transition and the time separation of the transitions, first recording means operative to record the changes in amplitude value between each transition and the next succeeding transition for a predetermined time portion of the electrical signal waveform for storing to store a first set of amplitude changes and the corresponding time separations, second recording means operative to store at least one predetermined, second set, of amplitude changes, and the corresponding time separations, of an electrical signal waveform corresponding to the variations of electromagnetic radiation derived from a predetermined source of electromagnetic radiation, comparing means operative to compare the first stored set of amplitude changes and corresponding time separations with the said at least one second stored set of amplitude changes and corresponding time separations, and output means responsive to the comparison carried out by the comparing means to determine whether the source sensed by the sensing means is a fire and to produce an output indication accordingly.