In our dissertation work, an approach has been made to analyze the effect of free space transfer function by considering various parameters like path loss factor, atmospheric turbulence, pointing errors on the performance of free space optical (FSO) communication system. The performance of the proposed free space optical communication system is studied by developing a MATLAB simulator. In our research work two cases are considered for two different probabilities when binary codes are generated by Bernoulli generator with 0.5 and 0.4. Finally, we evaluated the Bit Error Rate (BER) and signal to noise ratio (SNR) performance of the proposed system varying with different system parameters. The BER is highly degraded on severe atmospheric turbulence condition ever for a short distance of free space channel. The effect of path loss factor due to dense fog is also severe on the BER even though the turbulence effect and free space distance is short. After Bernoulli generator spectrum analyser used to see result in frequency domain and later on both signal are convoluted with Hadmard code to achieve orthogonality criterion and the passed through AWGN channel and 10db SNR also added the both signal are processed with FSO circuit with different parameters condition and finally BER is received on display. FSO communication is latest trend technology and during this lot of problem have to face and one important parameter is that range. Signal cannot be transmitted to long distance if we transmit then BER also increased and due to which communication is not reliable so we required to work on distance and power utilized and atmospheric condition so that data can be transmitted successfully for a long distance