Abstract: A system and method for noise suppression using signal strength ratio metric modulated light are disclosed. The system may include a light source, a light sensor, and a control circuit. The control circuit may be to generate a signal strength ratio metric modulated signal at a modulation depth. The control circuit may also be to send the signal strength ratio metric modulated signal to the light source to cause the light source to emit a signal strength ratio metric modulated light beam. The control circuit may additionally be to receive a reflected light signal from the light sensor. The reflected light signal may include a signal indicative of a reflection of the signal strength ratio metric modulated light beam and a signal indicative of a noise light.

Abstract: A system and method for the use of digital analysis to filter out extraneous light are disclosed. The system may include a light source to emit a light beam in a smoke detector. The system may include a first light sensor in the smoke detector to receive a reflected light beam corresponding to the light beam reflecting off a smoke particle. The system may include a second light sensor in the smoke detector to receive a noise light corresponding to ambient light in the smoke detector. The system may include a control circuit. The control circuit may be to receive the reflected light signal from a first light sensor indicative of the reflected light beam and to receive a noise signal from the second light sensor indicative of the noise light. The control circuit may be to reduce noise from the reflected light signal based on the noise signal.