Free Space Optical Communication (System Design, Modeling, Characterization and Dealing with Turbulence) || 2. Real-time measurement of meteorological parameters for estimating low altitude atmospheric turbulence strength (C2 n)

摘要： The major factor that limits the performance of Free Space Optical Communication (FSOC) is atmospheric turbulence which fluctuates over time in accordance with the variations in local meteorological parameters. Estimating the atmospheric turbulence strength (C2n) from measurement data is significant for finding the data rate the system is capable of operating at under different outdoor local environmental conditions. Hence, a low cost customized system for continuously measuring local meteorological data is developed and presented in this chapter. A field test scintillometer setup is established for a link range of 0.5 km at an altitude of 15.25 m. Specialized sensors are interfaced to the digital architectures to acquire the real-time data corresponding to atmospheric changes. The accuracy and performance of the measurement system are tested against standard instruments and the maximum correlation coefficients of 99.92 %, 99.63 %, 99.73 %, and 99.88 % are achieved for wind speed, temperature, relative humidity and pressure respectively. Atmospheric turbulence strength is estimated for the diurnal period using measured meteorological data. The validations of the estimated results with the scintillometer measurement are also analyzed. The weather profile and corresponding C2n variations at our test field for different seasons over a one year period are presented and the results are analyzed.