Effects of modulation types on the performance of FSO communication systems

In this thesis, the Bit Error Rate (BER) performance of Binary Phase Shift Keying (BPSK) modulation used in Free Space Optics (FSO) communication systems under marine atmospheric conditions is investigated. Marine atmospheres have a more complex structure than land atmospheres with effects such as high humidity, temperature differences and aerosol particles. These atmospheric factors cause turbulence in the propagation of optical signals, which directly affects the system performance. In this study, the BER performance of BPSK modulation is analyzed by MATLAB simulations considering weak and strong turbulence conditions. Within the scope of the study, parameters such as wavelengths, source field sizes, internal scale and atmospheric structural constant are varied and their effects on BER are evaluated. The results show that low BER values are obtained at short distances, but the effect of turbulence becomes dominant as the distance increases. It is also found that physical parameters such as higher photodetector sensitivity, favorable load resistance and low noise factor improve the system performance. This thesis presents a detailed analysis of the performance of BPSK modulation in marine atmospheres, which is limited in the literature, and aims to develop optimization recommendations for future FSO system designs