Real-time measurement of meteorological parameters for estimating low-altitude atmospheric turbulence strength (Cn2)

The major factor that limits the performance of Free Space Optical Communication is atmospheric turbulence which fluctuates over time in accordance with the variations in local meteorological parameters. Estimating the atmospheric turbulence strength C_n² with the measurement data becomes significant to find the data rate the system is capable of operating under different outdoor local environmental conditions. Hence, a low cost customised system for continuously measuring the local meteorological data is developed and presented in this study. A field test scintillometer setup is established for a link range of 0.5 km at an altitude of 15.25 m. Specialised 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. An experimental model to estimate C_n² using measured meteorological data is developed and the atmospheric turbulence strength is estimated. The validations of the estimated results with the scintillometer measurement are also analysed. The weather profile and corresponding C_n² variations at our test field for different seasons in 1 year period are presented and the results are analysed.