Infrared occupancy sensor

An occupancy sensor, comprising:

• an infrared sensor;
• a variable bandpass filter operably coupled to the infrared sensor comprising:
• a digital potentiometer adapted to control a gain of the bandpass filter;
• a digital potentiometer adapted to control a tuning of the bandpass filter;
• and
• a digital potentiometer adapted to control a ratio of a center frequency of the bandpass filter to a bandwidth of the bandpass filter;
• and
• a controller operably coupled to the infrared sensor and the variable bandpass filter comprising:
• a bandpass filter engine adapted to control the variable bandpass filter;
• a doppler shift engine adapted to characterize the signals filtered by the variable bandpass filter;
• and
• an occupancy sensing engine adapted to characterizations of the Doppler shift engine to determine the presence of absence of the occupant within the defined region;
• wherein the controller is adapted to:
• filter the signals generated by the infrared sensor using the variable bandpass filter, and
• process the filtered signals to determine the presence or absence of an occupant within a defined region.

A method of operating an occupancy sensor, comprising:

• monitoring thermal energy within a defined region to generate signals representative of the thermal energy within the defined region;
• filtering the signals using a variable bandpass filter;
• and
• processing the filtered signals to determine a presence or absence of an occupant within a defined region.

A method of operating an occupancy sensor, comprising:

• monitoring thermal energy within a defined region and generating signals representative of the thermal energy;
• filtering the signals using a variable bandpass filter;
• controlling a ratio of a center frequency to a bandwidth of the variable bandpass filter;
• sweeping the variable bandpass filter upwardly along a range of frequencies;
• then sweeping the variable bandpass filter downwardly along a range of frequencies;
• time averaging an amplitude of the filtered signals;
• comparing the time averaged amplitudes of the filtered signals;
• determining if a filtered signal indicates a source of thermal noise within the defined region;
• and
• determining if a filtered signal indicates a presence of an occupant within the defined region.

A system for operating an occupancy sensor, comprising:

• means for monitoring thermal energy within a defined region and generating signals representative of the thermal energy;
• means for filtering the signals using a variable bandpass filter;
• and
• means for processing the filtered signals to determine a presence or absence of an occupant within a defined region.

A system for operating an occupancy sensor, comprising:

• means for monitoring thermal energy within a defined region and generating signals representative of the thermal energy;
• means for filtering the signals using a variable bandpass filter;
• means for controlling a ratio of a center frequency to a bandwidth of the variable bandpass filter;
• means for sweeping the variable bandpass filter upwardly along a range of frequencies;
• means for then sweeping the variable bandpass filter downwardly along a range of frequencies;
• means for time averaging an amplitude of the filtered signals;
• means for comparing the time averaged amplitudes of the filtered signals;
• means for determining if a filtered signal indicates a source of thermal noise within the defined region;
• and
• means for determining if a filtered signal indicates a presence of an occupant within the defined region.

A computer program for operating an occupancy sensor, comprising program instructions for:

• monitoring thermal energy within a defined region to generate signals representative of the thermal energy within the defined region;
• filtering the signals using a variable bandpass filter;
• and
• processing the filtered signals to determine a presence or absence of an occupant within a defined region.

A computer program for operating an occupancy sensor, comprising program instructions for:

• monitoring thermal energy within a defined region to generate signals representative of the thermal energy within the defined region;
• filtering the signals using a variable bandpass filter;
• controlling a ratio of a center frequency to a bandwidth of the variable bandpass filter;
• sweeping the variable bandpass filter upwardly along a range of frequencies;
• then sweeping the variable bandpass filter downwardly along a range of frequencies;
• time averaging an amplitude of the filtered signals;
• comparing the time averaged amplitudes of the filtered signals;
• determining if a filtered signal indicates a source of thermal noise within the defined region;
• and
• determining if a filtered signal indicates a presence of an occupant within the defined region.