Method of determining the operating period of a danger warning system and danger warning system

摘要

The method involves determining a filtered signal (2) of measurement- or operation value (1) of a danger warning system i.e. fire alarm, by exponentially filtering first and second orders with filter parameters, and weighted summing of results from filtering the first and second orders. A momentary increase of the filtered signal is determined from the filter parameters and another filter parameter. Information about time period until exceeding or falling below a predetermined reference value through the filtered signal is determined by increasing the filtered signal. An independent claim is also included for a danger warning system including a signal processing device.