Fire sensor cross-correlator circuit and method
Patent 4639598 Issued on January 27, 1987. Estimated Expiration Date: 
May 17, 2005. Estimated Expiration Date is calculated based on simple USPTO term provisions. It does not account for terminal disclaimers, term adjustments, failure to pay maintenance fees, or other factors which might affect the term of a patent.
May 17, 2005. Estimated Expiration Date is calculated based on simple USPTO term provisions. It does not account for terminal disclaimers, term adjustments, failure to pay maintenance fees, or other factors which might affect the term of a patent.Patent ReferencesOptical discriminating fire sensor Patent #: 4469944 InventorsAssigneeApplicationNo. 06/735039 filed on 05/17/1985US Classes:250/339.15, Sensing flame or explosion250/340, Methods340/578By radiant energyExaminersPrimary: Fields, Carolyn E.Attorney, Agent or FirmInternational ClassesF23N 5/08 (20060101)G08B 17/12 (20060101) G08B 29/18 (20060101) G08B 29/00 (20060101) AbstractA 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.Field of SearchMethods | |
