Research On Key Techniques Of Wideband Satellite Communication System

The past decade, due to the unprecedented prosperity of the Internet and satellite communication technologies, the rapid development of its own, the rise of broadband satellite communications, and will gradually been widely used, there has been remarkable rapid development. At present, two types of broadband satellite communication system are under development:high-power high-frequency high-capacity satellites deployed at traditional geostationary (GEO) orbits, and large constellations of satellites deployed at much lower (LEO) orbits.In this dissertation, we research stressly three key techniques of broadband satellite communication at geostationary (GEO) orbits, accordingly obtain following practical results:1. Lower Signal-to-Noise demodulation technology, we. first present a communication system scheme based on parallel pilot frequency-assisted and LDPC channel coding; This as a basis, successfully developed a modem equipment; Theoretical analysis, simulation and equipment test results show that the proposed algorithms and equipment scheme is good to meet project needs, Technical specifications of the system in China is a leading.2. High-rate16APSK modulation and demodulation arithmetic:, in the absence of pilot cases:With the blind estimation method to complete the symbol timing, large frequency offset estimation, carrier phase synchronization tasks; through the use of MMSE algorithm, made12re-correcting phase ambiguity to four heavy phase ambiguity; the design of the AGC algorithm for the two models, we can quickly and accurately quantify the control of the input signal amplitude; A set of complete and practical scheme is presented in order to FPGA core16APSK modulation, channel simulation, and demodulation, the simulation results show that the algorithm and design is excellent performance and innovative.3. TDM/FDMA sharing frequency spectrum transmission technology, we first propose a new communication system of TDM/FDMA sharing frequency spectrum transmission; based on the results of interference analysis and design of the TDM/FDMA system, a total of spectrum interference with treatment programs; gives a total of TDM/FDMA system sharing frequency spectrum transmission performance analysis, simulation and evaluation methods; The results show that TDM/FDMA sharing spectrum transmission technology can effectively improve the system frequency spectrum efficiency, has a good application prospects.4. In the system simulation research, the paper proposes a time-varying group delay filter based on the signal sampling rate conversion method. The method was passed amended at any time after the quadrature down-converter low-pass filter or matched filter group delay values, achieve signal re-sampling and sampling rate conversion. Compared with existing methods, this algorithm can not only lower implementation complexity, but also to ensure that at a very low SNR does not decrease the output signal to noise ratio.