Patent ID: 6218950
Filing Date: 2001-04-17
Classification: G06K,G08B

Abstract:
Method for evaluating scattering signals of a fire detector, comprising:measuring the scattering signals at two scattering angles;determining an alarm threshold; andcomparing an alarm value with the alarm threshold, wherein the alarm value is determined as a function of the ratio of the scattering signals, the ratio of the scattering signals defining a factor F, F' withF=((S.sub.R /S.sub.V)-0.2)/0.6for (S.sub.R /S.sub.V) between 0.2 and 0.8, andF'=2-((S.sub.R /S.sub.V)-0.2)/0.2for (S.sub.R /S.sub.V) greater than 0.8,wherein the factor F, F' defines a brightness of an aerosol, with S.sub.R corresponding to a backscatter signal and S.sub.V corresponding to a forward scattering signal.