Siemens Aktiengesellschaft

Giuseppe Marbach

August Kaelin

Dani Lippuner

A scattered light smoke detector containing an optoelectronical assembly for measuring scatter signals detected below at least one forward scatter angle and at least one backscatter angle and evaluation electronics for determining an alarm value in accordance with the difference between the scatter signals. Smoke signals are produced from the scatter signals by means of a pre-processing step and a measured value is obtained from the smoke signals. The measured value is formed by a linear linking of the sum of the smoke signals to the difference between the smoke signals BW, FW or by establishing the value for the difference between the smoke signals. The linear linking is calculated according to the formula k(BW+FW)+k(BW&#x2212;FW), in which BW and FW are smoke signals and kand krepresent two constants that are influenced among others by an application factor that is dependent on the environmental conditions in the installation location of the detector.

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Hombrechtikon, Switzerland

Giuseppe Marbach