Dew-point Meter Design Based On MEMS And Digital Signal Processor

This article proposed a design of dew point hygrometer based on an MEMS capacitive sensor and digital signal processor technology to detect the dew point temperature of the atmospheric environment.This article first introduced the advantages and disadvantages of several dew point hygrometers and proposed a new dew point hygrometer to overcome the shortcomings of the traditional technology. This paper also described the proportional integral differential algorithm, which is applied to the automatic control system. Then, the article analyzed the hardware and software designs of the dew point hygrometer. The choice and application of the micro-controller, analog-to-digital converter, cooler and corresponding radiator were introduced. This design needed to achieve large amounts of data processing, high-precision data gathering and precise temperature controlling. Therefore, TMS320F2812, a digital signal processor, was used as the controller. Two high-precision analog-to-digital converters and a thermoelectric cooler were used in the hardware design. In order to achieve the control of the dew point hygrometer and visualization in the software, the pulse width modulation wave and visualization LabVIEW graphics window were used. Finally, this dew point hygrometer went through a comparison testing with an optical dew point hygrometer, which could be used as a reference standard. After a certain amount of data were measured by the dew point hygrometer, errors were calculated and analyzed. The results showed that the error was less than0.4℃.The dew point hygrometer, which is small size, low power consumption, fast response and low cost, is able to achieve the measurement of transient changes in atmospheric water vapor content requirements. The sensor is expected to be applied in the field of meteorological observation.