FIELD: physics.
SUBSTANCE: method includes evaluating scattered light signals in an optical alarm system and outputting both a weighted smoke density signal and a weighted dust/steam density signal. The particles which are to be detected are irradiated with light a first and a second wavelength range. The light scattered by the particles is converted into a first and a second non-standardised scattered light signal (IR', BL'). Both scattered light signals (IR', BL') are standardised with respect to one another in such a way that their amplitude profile for large particles such as dust and steam approximately corresponds. Furthermore, both standardised scattered light signals (IR, BL) are transformed into a corresponding polar angle and a corresponding distance as a polar coordinate of a polar coordinate system. Further, a corresponding a smoke density signal (R) and a corresponding dust/steam density signal (SD) are formed from the current distance value (L), wherein for this purpose the respective current distance value (L) is weighted as a function of a current polar angle value (α), in opposite directions to one another. Finally, the weighted smoke density signal (R) and the weighted dust/steam density signal (SD) are output for further evaluation of fire characteristics.
EFFECT: wider field of application of optical methods and devices for determining and evaluating scattered light signals.
11 cl, 5 dwg
