Research On Technology Of Synchronization And Demodulation In Satellite Communication System

In recent years, satellite broadband communication has become a research focus.And modulation/demodulation and synchronization of satellite communications systemare two key technologies.Firstly this dissertation describes the model of APSK modulation signal andanalyses two modulation signal models of16APSK and32APSK and severaldemodulation methods of APSK modulation signal. An improved demodulation methodfit for16APSK/32APSK modulation signals is proposed and simulated based on Matlabsoftware, and the advantages and disadvantages of these demodulation methods areanalyzed and compared.Then this dissertation introduces the carrier frequency offset, and researchesseveral estimation methods of carrier frequency offset. According to the projectrequirements, two improved carrier synchronization methods are proposed andsimulated, and a conclusion is drawn that these two methods have achieved betterperformance.Last, this dissertation introduces the timing synchronization loop, and analyzes thestructure of the timing synchronization loop. The function and structure of the modulesin the timing synchronization loop are analyzed in detail, and the calculation and impactof individual parameters in the loop are also analyzed. The performance of timingsynchronization loop is simulated under the conditions of the different sizes of thetiming deviation by using QPSK and8PSK modulation, and the results indicate that thedesign of timing synchronization loop can complete the timing error correction.