Photoelectric smoke detector with drift compensation

A smoke detector is disclosed that comprises a smoke detection chamber comprising: a light source operable to provide radiation to an interior space of the smoke detection chamber, and a light detector operable to receive radiation scattered by one or more radiation scatting particles in the interior of the smoke detection chamber; an alarm control module, in communication with the smoke detection chamber and a processor, operable to produce an alarm indicating a presence of a predetermined threshold of the one or more radiation scattering particles; a computer readable medium comprising instructions that when executed by the processor, cause the detector to perform an alarm compensation threshold method comprising: comparing a calibrated clear air voltage measurement with an average clear air voltage measurement; adjusting an alarm threshold sensitivity, based at least in part, on the comparison of the calibrated clear air voltage measurement and the average clear air voltage measurement.