Compensator in a detector device

1. A detector device comprising:

a light source disposed within a chamber;

a sensor disposed within the chamber;

a compensator circuit electrically coupled with the sensor; and

a controller operable to:

receive a sensor signal generated by the sensor;

determine a compensation factor to adjust the sensor signal;

generate a compensation offset signal based on the compensation factor;

output the compensation offset signal to the compensator circuit to produce a compensated sensor signal as an adjustment to the sensor signal;

energize the light source;

monitor the compensated sensor signal with respect to an alarm limit;

trigger an alarm event based on the compensated sensor signal exceeding the alarm limit;

de-energize the light source;

determine one or more error sources included in a clean air value of the sensor signal with the light source de-energized; and

determine the compensation factor as the adjustment needed to reach a target baseline clean air value representing a starting value for comparison to the alarm limit based on the one or more error sources.

2. The detector device of claim 1 , wherein the compensator circuit comprises:

an amplification circuit operable to amplify the sensor signal of the sensor as an amplified sensor signal; and

a summing circuit operable to sum the amplified sensor signal with the compensation offset signal to produce the compensated sensor signal.

3. The detector device of claim 2 , wherein the summing circuit is an analog circuit and the sensor is a photo detector sensor.

4. The detector device of claim 3 , further comprising:

an analog-to-digital converter operable to sample and quantize the compensated sensor signal as a digital value; and

a digital-to-analog converter operable to convert the compensation offset signal from a digital signal to an analog signal prior to summing at the summing circuit.

5. The detector device of claim 4 , wherein the sensor signal received at the controller is the amplified sensor signal as sampled and quantized through the analog-to-digital converter when the compensation offset signal has a zero offset value.

6. The detector device of claim 1 , wherein the controller is further operable to:

determine whether the compensated sensor signal has increased above a baseline value; and

increase the compensation offset signal until the compensated sensor signal is at or below the baseline value.

7. The detector device of claim 1 , wherein the controller is further operable to:

detect a hush request;

increase the compensation offset signal until the compensated sensor signal is below the alarm limit responsive to the hush request; and

reset the compensation offset signal after a predetermined period of time elapses from detection of the hush request.

8. The detector device of claim 1 , wherein the controller is further operable to:

monitor a temperature sensor to determine a current temperature value; and

determine the compensation factor based on the current temperature value and a temperature to compensation offset mapping.

9. The detector device of claim 1 , wherein the controller is further operable to:

track an average value of the compensated sensor signal over an extended time period; and

decrease the compensation offset signal based on the average value until the compensated sensor signal is at or below a long-term target value.

10. A method of operating a detector device, the method comprising:

receiving, at a controller of the detector device, a sensor signal generated by a sensor of the detector device;

determining, by the controller, a compensation factor to adjust the sensor signal;

generating, by the controller, a compensation offset signal based on the compensation factor;

outputting, by the controller, the compensation offset signal to a compensator circuit to produce a compensated sensor signal as an adjustment to the sensor signal;

determining, by the controller, whether the compensated sensor signal has increased above a baseline value;

increasing, by the controller, the compensation offset signal until the compensated sensor signal is at or below the baseline value;

monitoring, by the controller, the compensated sensor signal with respect to an alarm limit; and

triggering, by the controller, an alarm event based on the compensated sensor signal exceeding the alarm limit.

11. The method of claim 10 , further comprising:

amplifying the sensor signal of the sensor as an amplified sensor signal by an amplification circuit of the compensator circuit; and summing the amplified sensor signal with the compensation offset signal to produce the compensated sensor signal by a summing circuit of the compensator circuit.

12. The method of claim 11 , wherein the summing circuit is an analog circuit, the sensor is a photo detector, and the compensator circuit is external to the controller.

13. The method of claim 12 , further comprising: sampling and quantizing, by an analog-to-digital converter, the compensated sensor signal as a digital value; and converting, by a digital-to-analog converter, the compensation offset signal from a digital signal to an analog signal prior to summing at the summing circuit.

14. The method of claim 13 , wherein the sensor signal received at the controller is the amplified sensor signal as sampled and quantized through the analog-to-digital converter when the compensation offset signal has a zero offset value.

15. The method of claim 10 , further comprising:

de-energizing a light source in a chamber of the detector device, wherein the sensor is disposed in the chamber;

determining one or more error sources included in a clean air value of the sensor signal with the light source de-energized; and

determining the compensation factor as the adjustment needed to reach a target baseline clean air value representing a starting value for comparison to the alarm limit based on the one or more error sources.

16. The method of claim 10 , further comprising:

detecting a hush request;

increasing the compensation offset signal until the compensated sensor signal is below the alarm limit responsive to the hush request; and

resetting the compensation offset signal after a predetermined period of time elapses from detection of the hush request.

17. The method of claim 10 , further comprising:

monitoring a temperature sensor to determine a current temperature value; and

determining the compensation factor based on the current temperature value and a temperature to compensation offset mapping.

18. A method of operating a detector device, the method comprising:

receiving, at a controller of the detector device, a sensor signal generated by a sensor of the detector device;

determining, by the controller, a compensation factor to adjust the sensor signal;

generating, by the controller, a compensation offset signal based on the compensation factor;

outputting, by the controller, the compensation offset signal to a compensator circuit to produce a compensated sensor signal as an adjustment to the sensor signal;

tracking, by the controller, an average value of the compensated sensor signal over an extended time period;

decreasing, by the controller, the compensation offset signal based on the average value until the compensated sensor signal is at or below a long-term target value;

monitoring, by the controller, the compensated sensor signal with respect to an alarm limit; and

triggering, by the controller, an alarm event based on the compensated sensor signal exceeding the alarm limit.

19. The method of claim 18 , wherein a light source is disposed within a chamber of the detector device along with the sensor, the method further comprising:

determining, by the controller, one or more error sources of the sensor signal with the light source de-energized; and

determining, by the controller, the compensation factor as an adjustment needed to reach a target baseline value based on the one or more error sources.

20. The method of claim 18 , further comprising:

detecting, by the controller, a hush request;

increasing, by the controller, the compensation offset signal until the compensated sensor signal is below the alarm limit responsive to the hush request; and

resetting, by the controller, the compensation offset signal after a predetermined period of time elapses from detection of the hush request.