| Recently years, the aerospace science has improved a lot in our country. Different satellites for different tasks have to transport more and more data, resulting that spectrum resource is more and more nervous. One direction of satellite data transporting is high-order modulation. Traditional QAM modulation fits not well with satellite channel of non-linearity. The modulated signal range is smaller due to rounded constellation of APSK, which adapts to satellite channel and takes good advantage of spectrum resource. So APSK is the development trend of modulation in satellite data transport.This thesis is directed by related standard about DVB-S2 recommended by ETSI, the modulation and demodulation of 16 APSK is studied deeply. The main content is as followed:Scheme of 16 APSK modulation. The scheme of optimized constellation of 16 APSK is promoted, the producing process and shaping process of modulation signal is studied. The method of producing modulation signal is raised in the perspective of actual engineering practice combined with EVM.Scheme of 16 APSK demodulation. The method of variable sample/resample is raised to solve the problem of sample rate being divided by sample rate with remainder. The carrier synchronization is accomplished by three order loop. The bit synchronization is accomplished with Gardner algorithm after study deeply about the interpolation. The AGC control process is designed from the perspective of average amplitude and average power. A channel equalization algorithm based on CMA is proposed, and the hard decision algorithm is chosen by considering the resource use ratio. |
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