Patent ID: 7015807

Claim:
A method for detecting whether an audible alarm generated by a smoke detector is active, the audible alarm having an alarm period comprising a plurality of on periods and a plurality of off periods arranged in a predetermined temporal pattern, each of the on periods being a period during which an audible alarm sound is generated by the smoke detector, each of the off periods being a period during which no audible sound is generated by the smoke detector, the method comprising: detecting a peak amplitude in each of a plurality of sample periods, each of the sample periods corresponding to one of the expected on or off periods in a single alarm period; selecting a maximum peak amplitude from among the peak amplitudes; setting an amplitude threshold, the amplitude threshold being a function of the maximum peak amplitude; comparing each of the peak amplitudes to the amplitude threshold for each of the sample periods to determine which sample periods have a peak amplitude that exceeds the amplitude threshold; determining whether the audible alarm is active based at least in part on whether the temporal pattern of sample periods in which the peak amplitude exceeds the amplitude threshold matches the predetermined temporal pattern.