Patent ID: 8242899

Claim:
A retrofitted detector/alert system, comprising: a detector/alert device capable of generating an audible alert signal in response to detecting at least one of smoke, heat, and carbon monoxide, the detector/alert device mounted to a ceiling and connected to an AC power source; and a battery-powered supplemental alert generation device mounted to the ceiling within four feet of the detector/alert device, said supplemental alert generation device configured to monitor a detected sound level while operating in a relatively low power mode, and configured to transition into a higher power analysis mode when the detected sound level exceeds a threshold sound level, said higher power analysis mode being a mode in which the supplemental alert generation device analyzes at least a pattern of a received audio signal to determine whether an audible alert signal having a temporal-three pulse pattern or a temporal-four pulse pattern is heard, said supplemental alert generation device responsive to detection of a temporal-three audible alert signal by generating and outputting a relatively low frequency supplemental alert signal having a temporal-three pulse pattern that is synchronized in time with the temporal-three pulse pattern of the detected temporal-three audible alert signal, said supplemental alert generation device responsive to detection of a temporal-four audible alert signal by generating and outputting a relatively low frequency supplemental alert signal having a temporal-four pulse pattern that is synchronized in time with the temporal-four pulse pattern of the detected temporal-four audible alert signal.