The Design Of A Forward Scatter Wireless Visibility Meter

With the global atmospheric pollution is becoming increasingly serious, and as a direct characterization of air quality and visibility attracts more attention, many countries and regions have put it as indicator of air pollution. The visibility is one of the important parameters of the meteorological observation, because it is one of the important parameters of the near surface air pollution。 Visibility observation, can provide the basis for weather forecast, transportation and so on. Therefore, it is particularly necessary to research and design of a high precision, small size, real-time and easy operation of the visibility meter.In this paper, we design a forward scattering wireless visibility meter. We put forward a design scheme of the scattering visibility measuring device and structure based on the analysis of visibility measurement principle. The hardware part consists of transmitting module, receiving module, data processing module, wireless data transmission modules. The transmitting module transmits the infrared light emitting diode by the fixed frequency modulation constant current circuit. Faint light scattering produces infrared spread in the air, through the receiving module filter to reduce solar radiation, enhanced by photodiode receive focus. Through the signal amplifying and filtering circuit, so as to achieve the visibility and reflect the related communication signal and transmit signal frequency, reduces the interference of light and electricity. After the rectification of the signal through the A/D conversion module, the digital signal, and send data processing module for analysis and processing, in order to achieve the visibility of the results. Wireless data transmission module, using CC2530 wireless sensor network to transmit measurement data, to achieve the visibility measurement of wireless and networking. In software part, the use of C language programming to control the transmission of light signals, data acquisition and processing, and converted to the value of visibility. Using C# to develop the host computer software, so that the user remote operation and data monitoring. Finally, the method of improving the accuracy of visibility measurement is put forward through the analysis of error sources.Experimental results show that the system has high precision and real time performance, and it is convenient to use and maintain, and it can meet the requirements of meteorological stations.