A method of relative humidity (RH) measurement with on line temperature correction and data logging feature is described here. The RH sensor is a thermoset polymer capacitive type with on chip conditioning. Output voltage of RH to voltage converter is digitised using a 12-bit A/D converter and it is interfaced with an 8-bit microcontroller. Temperature correction of RH in real time is done using a temperature to digital converter interfaced with the microcontroller. The corrected data is displayed in a liquid crystal display and transmitted for on line monitoring and logging via RS232C. Calibration of the system is performed using standard saturated binary salt solutions. Accuracy and precision are found out. Hysteresis and ageing effect is discussed. The system performance is also compared with a dry/wet bulb psychrometer at different ambient conditions. The performance of the system in an industrial environment is presented.
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