The Department of Broadband Infocommunications and Electromagnetic Theory at the Budapest University of Technology and Economics joined the Alphasat TDP#5 propagation experiment on 01.02.2014. The main goal of this experiment is to study the Space-Earth propagation channel on special frequency bands that might have significance in future high speed and broadband communication.
During the design of Earth-space microwave links for communication systems, several phenomena that affect propagation have to be taken into consideration. There are numerous effects which can cause the attenuation of the signal: absorption by atmospheric gases, scattering and depolarization, loss of signal due to beam divergence, rain attenuation and tropospheric scintillation caused by atmospheric turbulence.
Tropospheric scintillation is a result of dynamic changes in the refraction index, which occurs during line-of-sight propagation when a signal meets atmospheric turbulence that causes fast fluctuations in the amplitude – and phase of the signal.
After an overview on related work and theoretical foundations, I present a study on scintillation using the parameter space of related ITU recommendations, where I study the impact of numerous parameters on frequency. Furthermore, a comparison is presented between measurement results and scintillation values calculated based on ITU recommendations.
The final part of the thesis work describes two different methods of modelling tropospheric scintillation. I reproduce a signal sequence reminiscent of scintillation by using Gaussian White Noise, and also via a method based on Markov chains.