No description available.

The aim of the master’s thesis is to acquaint the reader with Discrete Fourier Transform DFT and its introduction to spectral analysis descrete time signals. Furthermore it describes efficient computation of the DFT using the algorithm Fast Fourier Transform FFT and effects that appear in the DFT spectral analysis, the effect of the length of the DFT, the effect of the length of the segment of the analysed signal and the leakage. Next is explained the issue of the complex representation of real bandpass signals in the baseband, called the complex envelope of signals. This represenation uses the Hilbert Transform and the analytic signal. The thesis also describes the application library Real Time Toolbox of the software Matlab/Simulink, that uses the data acquition card AD622 allows to connect and process real signals in real time. In Matlab/Simulink with use this facilities is create the laboratory lesson, that simulating the complex represenation of real bandpass signals in real time.

The dissertation thesis deals with a study of an influence of a simultaneous incidence of an additive thermal noise and a multiplicative phase noise on the useful signal transmission in narrowband satellite communication systems. While the additive thermal noise affects the useful signal only on the receiver side of the communication system, the multiplicative phase noise is produced in all system oscillators. One investigates how the receiver filter bandwidth reduction takes effect on the influence of individual noise types. The thesis is divided into four units. The first one (chapters 4 and 5) solves the ways of modeling of both noise types. In the second part (chapter 6), on the simple example, the primary analysis of the phase noise influence is made. Basic modulation schemes used in the satellite communication are also discussed (chapter 7). Third part (chapter 8) is devoted to the modeling of a general digital system with a M PSK modulation made directly on the main carrier wave. The last part (chapter 9) describes the modeling of a digital system with a BPSK modulation on the auxiliary subcarrier wave followed by an SSB modulation on the main carrier wave. General conclusions are deduced from obtained simulation results.