The technical development in automatic fire detection is mainly governed by the rapidly increasing development of electronic components including microprocessors that opens a variety of new signal processing tools. Most applications used in automatic fire detection systems are aimed a t the improvement for system handling in the alarm or in the fault signal situation or at the improvement of automatic system monitoring. Only rather few attempts have been made to use modern electronic tools including software solutions to improve the detection capability. This article deals with a method to develop signal detection algorithms which can be used in automatic fire detection systems and which, in addition, can very well be realized as software controlled electronic circuits , e.g. as software program operated microcomputers or as special VLSI circuits . The method is based on a simple and fairly general model for the physically measurable signal in the vicinity of a developing fire and is therefore not restricted to a special kind of fire detector