Audio signals from the intercom speakers are applied to the channel inputs. The input circuitry automatically adjusts the dynamic range based on real-time ambient noise levels, which allows for the detection of five programmable audio patterns.
Instantaneous sound levels are sampled and stored in memory. Signal analysis incorporates both the instantaneous sample and a window-weighted average of the stored samples.
The alarms are generated based on the digital signal analysis and the set of pre-programmed parameters.