Abstract: A method for calibrating a test light to simulate a fire includes measuring a baseline resistance induced in a sensor cell of a two-color detector in response to a controlled fire. The method includes monitoring a test resistance induced in the sensor cell in response to exposure to emissions from a test light and adjusting the emissions of the test light until the test resistance of the sensor cell equals the baseline resistance of the sensor cell to achieve a calibration setting for the test light. A test light for a detector includes a housing and a first LED within the housing having a first emission wavelength. A second LED is within the housing. The second LED has a second emission wavelength. The second emission wavelength is different than the first emission wavelength.

Abstract: A method for calibrating a test light to simulate a fire includes measuring a baseline resistance induced in a sensor cell of a two-color detector in response to a controlled fire. The method includes monitoring a test resistance induced in the sensor cell in response to exposure to emissions from a test light and adjusting the emissions of the test light until the test resistance of the sensor cell equals the baseline resistance of the sensor cell to achieve a calibration setting for the test light. A test light for a detector includes a housing and a first LED within the housing having a first emission wavelength. A second LED is within the housing. The second LED has a second emission wavelength. The second emission wavelength is different than the first emission wavelength.

Abstract: An overheat sensor system is provided. A controller may create an aircraft temperature profile and may compare temperature sensor data to the profile. The system may provide an output indicating temperatures or fires.

Abstract: An overheat sensor system is provided. A controller may create an aircraft temperature profile and may compare temperature sensor data to the profile. The system may provide an output indicating temperatures or fires.

Abstract: A thermopile radiation detector (10) has an optical filter layer (16) that supports a thermopile detector (22) and, in addition, filters undesired wavelengths. The filtering is accomplished by selectively absorbing electromagnetic radiation at predetermined wavelengths. The use of the thermopile radiation detector simplifies the overall construction of a system that incorporates the detector by eliminating one focal point in the optical system. By altering the filter material, the number of layers of filter material, etc., a plurality of detectors can be constructed, each responsive to a different wavelength. In forming the detector, the filter can be deposited on a thin backing material such as aluminum. Examples of suitable filter materials include alternating layers of zinc selenide/magnesium fluoride or germanium/magnesium fluoride. After the filter is deposited, the backing is etched away and suitable thermocouples, such as bismuth/antimony, are deposited on one side of the filter.

Abstract: A fiber optic fire and overheat sensor system 10 includes a fiber optic cable 12 having a lens 14 at a distal to direct radiation from a fire 16 into the cable 12 and to a radiation detector 18 disposed at a proximal end of the cable 12. Detector 18 is coupled to a fire sensor 19. The detector 18 is sensitive to two wavelength bands including a short wavelength band of approximately 0.8 to approximately 1.1 microns and a long-wavelength band of approximately 1.8 to approximately 2.1 microns. A controller 21, such as a microprocessor, analyzes the fire sensor 19 output signals which correspond to the two spectral bands to determine if a fire is present. The system 10 further includes a body of fluorescent material 20 disposed at the distal end of the cable 12. The material 20 can be interposed between a reflecting surface, such as a mirror 22, and a lens, such as a collimating lens 24. A fiber optic coupler 26 and 26a launches radiation from a source 28, such as a laser diode, into the fiber optic cable 12.

Abstract: A fiber optic fire detection and temperature measurement system 10 includes a fiber optic cable 12 having a lens 14 at a distal to direct radiation from a fire 16 into the cable 12 and to radiation detector 18 disposed at a proximal end of the cable 12. Detector 18 is coupled to a fire sensor 20. Detector 18 is sensitive to three wavelength bands including a short wavelength band of approximately 0.8 to 1.1 microns, a mid-wavelength band of approximately 1.3 to 1.5 microns and a long-wavelength band of approximately 1.8 to 2.1 microns. A controller 22, analyzes the fire sensor 20 output signals which correspond to the two spectral bands to determine if a fire is present. The fiber optic conductor is doped with a material selected for its temperature dependent fluorescent emission characteristics. Radiation from a fire passes via cable 12 to the detector 18. A pulse of radiation from source 28 passes from a coupler 26 and 26a to the cable 12.

Abstract: A fiber optic fire detection and temperature measurement system 10 includes a fiber optic cable 12 having a lens 14 at a distal to direct radiation from a fire 16 into the cable 12 and to a radiation detector 18 disposed at a proximal end of the cable 12. Detector 18 is coupled to a fire sensor 20. The detector 18 is sensitive to three wavelength bands including a short wavelength band of approximately 0.8 to 1.1 microns and a long-wavelength band of approximately 1.8 to 2.1 microns. A controller 22, analyzes the fire sensor 20 output signals which correspond to the two spectral bands to determine if a fire is present. The fiber optic conductor of cable 12 includes an optical filter 32 having a temperature dependent radiation transmission characteristic. Radiation from a fire passes via cable 12 to the detector 18.

Abstract: An apparatus for the discharge of powder by a fluidic propellant is suitable for use as a fire extinguisher, the apparatus including a container wherein powder and propellant is pressurized prior to use of the apparatus. Discharge of the powder and the propellant from the container is accomplished by means of a diaphragm in a wall of the container, there being a gas generator contained within a well of the container for providing an overpressure which, in combination with the pressure to which the propellant has been charged, fractures the diaphragm. Thereupon, the propellant and the powder exits the container in a homogeneous stream. The overpressure is less than approximately 30 percent, preferably 20 percent of the pressure to which the propellant and the powder are subjected during a charging of the container with the powder and the propellant. The charge pressure is in the range of 400-600 p.s.i. so as to be many times greater than the pressure of an environment external to the container.

Abstract: A method and improved apparatus for generating and transmitting the distinguishing radiation characteristics of a fire, an ignition and fire, or an ignition without a fire, to a fire sensing system under test are disclosed. Varying radiant energy attributes of a fire, and in particular a hydrocarbon fire such as might be encountered in a vehicle fuel or engine compartment are safely generated by a blackbody transmitter 100, an ultraviolet transmitter 200 and an ignition flash transmitter 300, having appropriate radiation sources. The radiation sources may be conveniently assembled into a palm-sized radiation "head" 101. The transmitters may be selected sequentially to test installed fire sensing systems in aircraft or vehicles or during manufacture where the environment does not permit the use of an actual fire.

Abstract: Apparatus for sensing the ex(i)stence of a fire and providing a warning, if desired, with improved discrimination against the possibility of false alarms. Dual channel detectors are used, one detector being set to respond to incident radiation having a wavelength in the range of 0.8 to 1.1 microns while the other wavelength range is significantly displaced therefrom, being selected for wavelengths in the range from 14 to 25 microns. Reliability of true signal detection is further improved by the provision of separate flame flicker bandpass filters in the respective channels, these bandpass filters being set for different passbands. Circuits providing ratio discrimination, threshold detectors and delay circuitry are combined with the dual spectrum detectors and disparate flicker frequency filters to achieve improved performance.

Abstract: A fire sensor can perform a sophisticated analysis of the outputs of radiant energy detectors, while minimizing size, weight, and cost, by employing a microprocessor to analyze the detector outputs. In a preferred embodiment, an Intel 2920 Signal Processor is utilized as the microprocessor.

Abstract: A fire sensing system utilizing fiber optics to extend the physical range of radiation sensing elements into areas and environments which are physically inaccessible to, and/or destructive of, such sensors and their associated electronic circuitry. The fiber optics are combined with signal processing circuitry to achieve reliable fire sensing systems which present particular advantages in special applications.

Abstract: Apparatus for sensing the existence of a fire and providing a warning, if desired, with improved discrimination against the possibility of false alarms. Dual channel detectors are used, one detector being set to respond to incident radiation having a wavelength in the range of 0.8 to 1.1 microns while the other wavelength range is significantly displaced therefrom, being selected for wavelengths in the range from 14 to 25 microns. Reliability of true signal detection is further improved by the provision of separate flame flicker bandpass filters in the respective channels, these bandpass filters being set for different passbands. Circuits providing ratio discrimination, threshold detectors and delay circuitry are combined with the dual spectrum detectors and disparate flicker frequency filters to achieve improved performance.

Abstract: A fire sensor that can perform a sophisticated analysis of the outputs of radiant energy detectors, while minimizing size, weight, and cost, by employing a microprocessor to analyze the detector outputs. In one embodiment, an Intel 2920 Signal Processor is utilized as the microprocessor. An alternative embodiment incorporates an RCA 1802 microprocessor to achieve fire sensing while discriminating against false signal radiation.

Abstract: Circuitry for using the statistical properties of detected radiation in the time domain to discriminate between stimuli from fire and non-fire sources. Statistical discriminators for fire sensing may be combined with other types of sensors operating in the frequency domain for developing improved sensitivity with better security against false alarms. Such other types of sensors may include peak detectors, zero crossing detectors, second derivative-equal-to-zero detectors, for example. The invention determines the mean or average, the variance or standard deviation, the mean deviation, and the Kurtosis of sampled data in statistical analysis to discriminate between fires and non-fires.

Abstract: A hot air leak sensor for sensing jet engine bleed air leaks in an aircraft. Infrared detectors are combined with thermal re-radiating elements which are installed in air passages adjacent to the bleed air ducts and downstream of the region where a bleed air leak may occur. The elements are approximately 50% transmissive and 50% absorptive to infrared radiation with wavelengths within the range of approximately 4 to 20 micrometers. Incident radiation within the field of view of the detector is both transmitted and absorbed for re-radiation to the detector. If no incident radiation within the sensor field of view is available, the re-radiating element still responds to the increased airstream temperature resulting from the bleed air leak and supplies radiation to the detector to provide detection of the leak.

Abstract: A fire sensor apparatus of the type having a discriminating fire sensor portion for detecting radiation in at least two different spectral bands associated with a fire and for providing an output signal in response to predetermined amounts of radiation in those spectral bands associated with a particular size and type of fire to be detected. A novel heat sensor channel is provided, which provides a further output signal in response to an amount of detected heat radiation greater than that associated with the fire of the type and size to be detected. A heat override function is thereby provided to permit the generation of an output signal even when contaminants block the action of the discriminating fire sensor portion.

Abstract: A cross-correlation fire sensor circuit includes detectors responsive to heat and light radiation, respectively. Electrical signals from the detectors are processed in two distinct channels through low pass filters and samplers. The sampled signals from the two channels are multipled together and the products are summed over a selected interval to provide a correlation function. This function is compared with an adjustable threshold to provide an indication of fire sensing. The circuit is also included as an adjunct to an existing system to provide improved sensitivity for fire sensing in the presence of noise and enhanced discrimination against false alarms. A ratio window detector circuit is disclosed as an alternative cross-correlator for detected radiation.

Abstract: Described herein is a method and system for sensing explosive fires by the parallel processing of signals derived from both electromagnetic radiation and mechanical wave energy simultaneously emanating from or near the source of these fires. This diverse-stimuli sensing capability enhances the false alarm immunity of the system.