Design On Evaporation Channel Calibration Of AWS Data-Acquisition Unit

With the development of meteorological service, its meteorological data calibration work is more and more important. Accurate measurement of evaporation elements have affected all areas, in order to ensure the normal operation of automatic weather station evaporation channel of data-acquisition unit and improve the accuracy of meteorological observation,the evaporation channel of data-acquisition unit need to be regular calibration.So, it is necessary to design a reasonable and high precision calibration system to achieve evaporation channel calibration of data-acquisition unit to ensure that the evaporation capacity of output is accurate and reliable data.In order to guarantee the observational data quality of Automatic Weather Station,According to the meteorological industry standards and technical specifications of AWS,in this paper, the evaporation characteristics of the sensor output signal and the data collector channel performance index are analyzed and the research, the design goal of the calibration system is determined, the realization of current loop circuit simulation method, the output current by using this method the overall scheme of this system is designed.Calibration system with MSP430processor, hardware part design, high precision constant current module AD/DA conversion module, keys module, liquid crystal display module calibration system hardware platform, and put forward to reduce interference in the process of PCB production, the method of improving the precision of the system.System software design is divided into two parts of the software and PC software. The overall scheme of the software of singlechip processor system are presented, and data preprocessing are introduced respectively, ADC and DAC module functions and implementation process. Upper machine part put forward the whole scheme and introduces a serial port processing module functions and implementation process.In order to reasonable characterization of credibility and dispersion of the evaporation data, for its uncertainty evaluation is introduced. Analysis of the uncertainty sources, according to the evaluation and class B class A assessment method to evaluate the sources of uncertainty components, calculation and uncertain.In practical applications,calibrate data-acquisition unit evaporation channel regularly utilizing the calibration method designed in this paper.The experimental results show that the system is stable and reliable, high precision and can be used for accurate calibration of the evaporation channel of data-acquisition unit.