Weather Variations Influence on NRZ and RZ Modulation in Free Space Optical Systems

Free Space Optic (FSO) is used to overcome the shortcomings of ordinary optical fiber by using free space as the transmission medium. FSO has advantages such as large bandwidth, short installation time, high data transmission speed, and immunity to Electro Magnetic Interface (EMI). This research analyzes the effect of using NRZ and RZ modulation techniques for varying weather conditions on FSO systems. The FSO system with NRZ and RZ modulation is tested against 4 different weather conditions: very light mist, very light fog, drizzle, and strong rain. The simulation results show that the RZ modulation technique provides better test results than the NRZ modulation technique; the highest Q-Factor value for RZ modulation in very light mist weather is 38.4317 at a distance of 11 km. The Q Factor value of very light fog weather is 38.4473 at a distance of 3 km. The Q-Factor value of drizzling weather is 38.374 at a distance of 40 km. The Q-Factor value of heavy rain weather is 38.3156 at a distance of 6 km.