In this paper, we show the performance using varies data rate in free space optical communication system for a specific visual range and comparison between conventional technique and Dual Diffuser Modulation (DDM) technique to measuring bit-error-rates for free space optical communication system. The data rates used in this analysis are 155Mbps, 622Mbps, 2.5Gbps and 10Gbps. The effect of bit error rate in this varies data rate is depend on the range of FSO system. It shown that 155Mbps data rate is suitable used in FSO system for a long visual range. The comparison between technique shows that DDM technique can enhance the system performance in bit error rate and also improve the sensitivity of power received in the system.
