Image Number 3 for United States Patent #8117894.
A sensor system issues measurement commands at a predetermined regular rate. If a measurement indicates that a gas of interest is present, then the sensor system is signaled to wake-up thereby pulsing a heater for the sensor element that improves the accuracy of measurements. Measurements of humidity, temperature and gas concentration are made. If the gas of interest is detected then the data is used to indicate a compensated gas measurement. The gas level is classified as to its hazard and an adaptive detection algorithm is used to set an activity mode. If the gas of interest is not detected, the adaptive detection algorithm is used to set a sleep mode that saves power. Measurement rates are kept constant while heater power is controlled to reduce power consumption. Measurement rates are changed to increase concentration sensitivity.