Lightwave Transmission Characteristics Testing Multi-channel Data Acquisition Technology Research

The effect of atmospheric attenuation and turbulence will lead to energy attenuation, angle of arrival fluctuations, light intensity scintillation, beam drift and beam spreading phenomena in the process of laser light transmission in the atmosphere. All of this will seriously affect the reliability and stability of optical communication. In order to improve the quality of optical communication and the level of optical communication equipments, we will need to learn more about light atmospheric transmission characteristics to make sure the important module design parameters of optical communication equipment development (such as the antenna aperture size, optical transmit power size, etc).This subject from a light wave propagation properties testing project of one ministry. The project requirements for design testing equipment of atmospheric parameters measurement and laser propagation in the atmosphere measurement. Test equipment should be have the characteristics of complete test environment parameters and easy to use,carry and install.The multi-channel data acquisition system development of the test apparatus is required. The system design objectives: achieve automatic testing for the key parameters of optical communication atmosphere channel, reduce testing time , improve the efficiency of testing and making the testing process automation, simplification.Firstly, the background and origin of the topic, research status, development trend and the main research contents of this paper are introduced. Secondly, the research of atmospheric turbulence theory and its impact on light transmission are discussed. And the necessity of testing light wave transmission characteristics is analyzed in the behind. Then the needs analysis of collection system and the select reason of acquisition parameters are introduced. The system includes signal acquisition module, data processing module and data transmission module. Then, each module divided again. The signal acquisition module includes temperature, humidity, air pressure, rainfall, wind direction and wind speed of six meteorological data collection section and GPS section. The FPGA chip of data processing section adopts the EP3C25F324 of ALTERA companies. Its application in this paper reflected the SOPC system integration, high flexibility. Data transmission part adopts GPRS wireless and RS-485 cable two ways to transmit data. After the hardware design description is a description of the software. It divided by the application modules and described each module of the software design and debugging. In the last section, the Nios II system module structure, content and hardware configuration are detailed design. Finally, the experiment to receive data and experimental results of weather data receiver, GPS data reception, GPRS Communication and end-user software are presented.The test results show that the module design is achieved the original design goals.