Design of precision measurement circuits for the relative humidity

Yanpeng Wang; Guanwang Gao; Zhanyou Sha

doi:10.1117/12.836661

10 July 2009 Design of precision measurement circuits for the relative humidity

Yanpeng Wang, Guanwang Gao, Zhanyou Sha

Proceedings Volume 7490, PIAGENG 2009: Intelligent Information, Control, and Communication Technology for Agricultural Engineering; 74900F (2009) https://doi.org/10.1117/12.836661
Event: International Conference on Photonics and Image in Agriculture Engineering (PIAGENG 2009), 2009, Zhangjiajie, China

Abstract

The two methods of the relative humidity measurement are introduced in this paper. The one is adopting transistor and operational amplifier to compose a logarithmic amplifier, by which to realize the linearization of exponent mode character curve of moisture-sensitive resistor. And using the positive temperature coefficient of the adjustable current source (+0.33%/°C) compensate the negative temperature coefficient of the thermistor (-0.36%/°C). Zero temperature drift is realized by the methods and the measurement accuracy reached ±2%. The two is adopting intelligent temperature/relative humidity sensor, which combined the multiple parameter sensor and transmitter, to realize the accurately measurement not only of the relative humidity, but also of the temperature and dew point. Through the 2-wires serial port the system can be connected to MCS-51 MCU. The accuracy of the relative humidity measurement is ±1.8%; the nonlinear error can be reduced to ±0.1% after software arithmetic compensation. The temperature range measured is -40~ + 123.8°C. The accuracy of dew point measurement is ‹±1°C

Citation Download Citation

Yanpeng Wang, Guanwang Gao, and Zhanyou Sha "Design of precision measurement circuits for the relative humidity", Proc. SPIE 7490, PIAGENG 2009: Intelligent Information, Control, and Communication Technology for Agricultural Engineering, 74900F (10 July 2009); https://doi.org/10.1117/12.836661

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