Influence of simulated atmospheric effect combined with modulation formats on FSO systems

Abstract

This article describes the possibility of using the Software Defined Radio (SDR) for modulation of the optical laser beam by advanced m-PSK and m-QAM modulations with regard to influence of simulated atmospheric effect, in our case rain in simulation acrylate box. There were tested the laser sources emitting the wavelengths 650 and 850 nm for comparison their behaviour in simulated atmospheric effect: rain (heavy, light, drizzle). By the help of the equipment NI USRP 2920 we could flexibly and sophisticated change the modulation formats without a necessity of creating complex electronic circuits ensuring modulation and demodulation of communication wireless signal. To make conclusions regarding the use of SDR for OWC, we performed a variety of tests in order to determine the resistance of the modulation formats to the simulated atmospheric effect with the aid of the Error Vector Magnitude (EVM) and Modulation Error Ratio (MER) parameters.