Detecting fires

The detection signals regarding the temperature or smoke concentration generated due to the fire are sampled. The sampled data is processed by being averaged. An occurrence of a fire is determined on the basis of the processed data, i.e. - the averaged data, after completion of the averaging processes. The detection signals which are used for the fire determined are obtained by performing a moving mean calculation of a plurality of sampled data as one group and/or by executing a simple mean calculation of a plurality of moving mean data as one group.