Studium vlivu atmosférických jevů na optický bezvláknový spoj

Abstract

This bachelor thesis focuses on the analysis of atmospheric phenomena and their impact on the reliability and quality of Free-Space Optical links. The primary objective was the full deployment of an FSO communication link utilizing professional MRV TS5000/G terminals and covering a distance of 1,466 meters between the Rectorate building of VŠB-TUO and the Ostrava Planetarium pylon. Subsequently, the link was used for long-term monitoring of the effects of weather conditions on laser beam propagation. A network of IoT weather stations was installed to collect local meteorological data, including temperature, relative humidity, and atmospheric pressure.

The gathered meteorological data were software-synchronised with the Received Signal Strength Indicator (RSSI) values. Analysis of the data from a 30-day measurement period demonstrated a strong correlation between the quality of the optical link and the state of the atmosphere. The measurements confirmed that fog causes the most significant signal attenuation (due to Mie scattering), and its presence can be reliably predicted using dew point depression calculations. Furthermore, the thesis analyses the impact of atmospheric turbulence on signal fluctuation using mathematical models to estimate the refractive index structure parameter ($C_n^2$). The results revealed a distinct daily cycle of turbulence driven by solar radiation, which causes significant scintillation of the received optical signal during daylight hours.