Experimental Study of Sand-Storm Effect on Digital FSO Communication Link

Over the last two decades, Free Space Optical (FSO) communication has become more and more interesting topic of research, as an alternative to radio frequency communication. In this paper we have presented the analysis of digital FSO system performance, under the sand-storm environment. We designed an indoor chamber, to simulate the effect of sandstorm, where the speed of the wind, blowing sands, and turbulence was created, varied and maintained over a long period of time using appropriate ambiance set-up. We created straight laser link through laser diode and signal detected by photo detector. Even we varied the sand storm speed in both directions along with the optical link (horizontal) and perpendicular to the optical link (vertical). After that we had an experimental study about how the Q-factor and bit error rate (BER) is changing. Most of the earlier studies of FSO had been accomplished in the environmental continents of Europe, East Asia, and North America; where the main atmospheric effects are due to fog, rain, snow, smoke and turbulence. It has been seen in the preceding studies that, the effects of sand and dust have been ignored, because they do not exist in the terrestrial atmosphere. Based on the visibility range, according to the World Meteorological Organization, we categorized the types of sand, like severe dust storm, dust storm, blowing dust and dust haze. We observed the signal scattering, absorption and fluctuation in each condition. We obtained the FSO communicative quantitative analysis of the parameters, like atmospheric transmittance and attenuation coefficient, Quality factor (Q-factor) and Bit Error Rate (BER) in each condition. The results which we obtained from the simulation, show that as the speed of the sand wind increases the Q-factor reduces and BER increases. The maximum wind speed achieved by this chamber is 4.8 ms which is nearly efficient to the sand storm scenario. This is the novelty of this research.