Devices, methods, and systems for a self-calibrating fire sensing device are described herein. One device includes a first transmitter light-emitting diode (LED) configured to emit a first light, a second transmitter LED configured to emit a second light, a first photodiode on-axis with the first transmitter LED, wherein the first photodiode is configured to select a first gain or a second gain of a first variable gain amplifier and detect an LED emission level of the first light responsive to selecting the first gain and detect a scatter level of the second light responsive to selecting the second gain, a second photodiode on-axis with the second transmitter LED, wherein the second photodiode is configured to select a third gain or a fourth gain of a second variable gain amplifier and detect an LED emission level of the second light responsive to selecting the third gain and detect a scatter level of the first light responsive to selecting the fourth gain, and a controller configured to recalibrate the fourth gain responsive to the detected LED emission level of the first light and recalibrate the second gain responsive to the detected LED emission level of the second light.

Devices, methods, and systems for a self-calibrating fire sensing device are described herein. One device includes a first transmitter light-emitting diode (LED) configured to emit a first light, a second transmitter LED configured to emit a second light, a first photodiode on-axis with the first transmitter LED, wherein the first photodiode is configured to select a first gain or a second gain of a first variable gain amplifier and detect an LED emission level of the first light responsive to selecting the first gain and detect a scatter level of the second light responsive to selecting the second gain, a second photodiode on-axis with the second transmitter LED, wherein the second photodiode is configured to select a third gain or a fourth gain of a second variable gain amplifier and detect an LED emission level of the second light responsive to selecting the third gain and detect a scatter level of the first light responsive to selecting the fourth gain, and a controller configured to recalibrate the fourth gain responsive to the detected LED emission level of the first light and recalibrate the second gain responsive to the detected LED emission level of the second light.

A motion detector includes a microwave-based module to detect movement. Intermediate processing circuitry is coupled to an output from the module. The processing circuitry is activated intermittently to produce first and second pulsed output signals. Cross-correlation circuitry processes the two signals to produce a motion indicating output signal.

Devices, methods, and systems for a self-calibrating fire sensing device are described herein. One device includes an adjustable particle generator and a variable airflow generator configured to generate aerosol having a particular particle size and optical scatter properties at a controllable density level, a first transmitter light-emitting diode (LED) configured to emit a first light that passes through the aerosol, a second transmitter LED configured to emit a second light that passes through the aerosol, a photodiode configured to detect a scatter level of the first light that passes through the aerosol and detect a scatter level of the second light that passes through the aerosol, and a controller configured to calibrate a gain of the photodiode based on the detected scatter level of the first light, the detected scatter level of the second light, and the controllable aerosol density level.

Devices, methods, and systems for a self-calibrating fire sensing device are described herein. One device includes an adjustable particle generator and a variable airflow generator configured to generate aerosol having a particular particle size and optical scatter properties at a controllable density level, a first transmitter light-emitting diode (LED) configured to emit a first light that passes through the aerosol, a second transmitter LED configured to emit a second light that passes through the aerosol, a photodiode configured to detect a scatter level of the first light that passes through the aerosol and detect a scatter level of the second light that passes through the aerosol, and a controller configured to calibrate a gain of the photodiode based on the detected scatter level of the first light, the detected scatter level of the second light, and the controllable aerosol density level.

Devices, methods, and systems for a self-calibrating fire sensing device are described herein. One device includes an adjustable particle generator and a variable airflow generator configured to generate aerosol having a particular particle size and optical scatter properties at a controllable density level, a first transmitter light-emitting diode (LED) configured to emit a first light that passes through the aerosol, a second transmitter LED configured to emit a second light that passes through the aerosol, a photodiode configured to detect a scatter level of the first light that passes through the aerosol and detect a scatter level of the second light that passes through the aerosol, and a controller configured to calibrate a gain of the photodiode based on the detected scatter level of the first light, the detected scatter level of the second light, and the controllable aerosol density level.

Devices, methods, and systems for a self-calibrating fire sensing device are described herein. One device includes an adjustable particle generator and a variable airflow generator configured to generate aerosol having a particular particle size and optical scatter properties at a controllable density level, a first transmitter light-emitting diode (LED) configured to emit a first light that passes through the aerosol, a second transmitter LED configured to emit a second light that passes through the aerosol, a photodiode configured to detect a scatter level of the first light that passes through the aerosol and detect a scatter level of the second light that passes through the aerosol, and a controller configured to calibrate a gain of the photodiode based on the detected scatter level of the first light, the detected scatter level of the second light, and the controllable aerosol density level.

There is provided a method of operating a device to generate a target sound that is audible to a user of the device, the method comprising measuring background noise in an environment in which the device is located; using a perceptual loudness model to predict an audibility of the target sound to the user of the device based on the measured background noise; using the output of the perceptual loudness model to determine a gain value that is to be applied to a source signal used to generate the target sound in order to provide at least a desired level of audibility of the target sound to the user; applying the determined gain value to the source signal to produce a modified source signal; and generating the target sound using the modified source signal.

There is provided a method of operating a device to generate a target sound that is audible to a user of the device, the method comprising measuring background noise in an environment in which the device is located; using a perceptual loudness model to predict an audibility of the target sound to the user of the device based on the measured background noise; using the output of the perceptual loudness model to determine a gain value that is to be applied to a source signal used to generate the target sound in order to provide at least a desired level of audibility of the target sound to the user; applying the determined gain value to the source signal to produce a modified source signal; and generating the target sound using the modified source signal.

Devices, methods, and systems for a self-calibrating fire sensing device are described herein. One device includes a first transmitter light-emitting diode (LED) configured to emit a first light, a second transmitter LED configured to emit a second light, a first photodiode on-axis with the first transmitter LED, wherein the first photodiode is configured to select a first gain or a second gain of a first variable gain amplifier and detect an LED emission level of the first light responsive to selecting the first gain and detect a scatter level of the second light responsive to selecting the second gain, a second photodiode on-axis with the second transmitter LED, wherein the second photodiode is configured to select a third gain or a fourth gain of a second variable gain amplifier and detect an LED emission level of the second light responsive to selecting the third gain and detect a scatter level of the first light responsive to selecting the fourth gain, and a controller configured to recalibrate the fourth gain responsive to the detected LED emission level of the first light and recalibrate the second gain responsive to the detected LED emission level of the second light.