Patent ID: 8395501

Claim:
A hazardous condition detection system, comprising, a housing containing a sensor package, the sensor package containing a hazardous condition sensor, the hazardous condition sensor being exposed to the ambient environment and taking periodic readings of the ambient environment; an alarm circuit coupled to the sensor package and disposed in the housing; a microprocessor coupled to the alarm circuit, the microprocessor having a memory storage device containing a clean air reading and a plurality of alarm thresholds differential values, each of the plurality of alarm thresholds differential values being associated with a predetermined set of sensor readings indicative of a hazardous condition in the ambient environment, where said microprocessor periodically receives a raw sensor reading from the sensor package and preprocesses said received raw sensor reading using at least three distinctive filtering constants to generate a set of at least three conditioned sensor readings from each raw sensor reading received and where said microprocessor accumulates a plurality of sets of conditioned sensor readings, and selects an alarm threshold differential value from a plurality of stored alarm thresholds differential values based on the rate of change of the conditioned sensor readings in a first subset of accumulated conditioned sensor readings generated from a common filtering constant, and generates an alarm threshold from the selected alarm threshold differential value.