Model-Free Ber Measurement in Free Space Laser Communication Link

Wireless Digital Laser Communication Link (WDLCL) is an emerging technology and alternate to the conventional RF / Fiber link with numerous advantages / applications. The data link quality can be best estimated by measuring the Bit Error Rate (BER) in WDLCL. Since the characteristics of WDLCL severely affected by the atmosphere, an experimental based study about the turbulence medium becomes significant. In this paper, the complete theoretical concepts related to the challenges of WDLCL are listed. The Opto-electronic architecture (Tx and Rx) developed in this research is detailed with the necessary photographs. The core design of the low-cost BER Tester (BERT) is developed in the reconfigurable Field Programmable Gate Array (FPGA) is explained. The BER is measured in various atmospheric conditions for different beam radius and link distance and the observations are reported. Over a long period of time, real-time experimental data was continuously collected and the results were analyzed. Beam scintillation, spreading and wandering were accounted as the atmospheric turbulent effects on the laser beam with beam steering system. The experimental results reveal that atmospheric turbulence has a significant impact on the BER.