The Research Of 600Mbps QPSK High Data-rate Demodulator

The data transmission system is a significant component of the satellite load, while the modem is one of the key technologies of the data transmission of satellite system as well as an important restriction factor in the study of high data-rate transmission system.The research on modem technology with high data-rate transmission makes a big difference in improving data transmittability of a satellite system. Soon after, it will also be widely applied in satellite data transmission system and communicaton transmission system in our country. So it makes profound significance to choose the development of high-speed demodulator as my subject of academic dissertation.In this paper, plenty of research on demodulation technology has been done based on the development of the 600Mbps demodulator. The demodulation becomes not only a critical but also a difficult factor in modem technology even in whole data transmission system because it involves carrier recovery and time synchronization.In the paper, firstly, a lot of theories on digital demodulation are deeply studied. Because of the rate limitation of digital components, it is very difficult to realize a thoroughly serial digital modulation whose transmission speed is as high as 600Mbps. So a parallel demodulation algorithm is put forward.Then the carrier recovery scheme combining frequency error detector with carrier track loop, is designed and through the scheme, carrier capture and track under a large frequency offset can be implemented. At last, some algorithms discussed in the paper are simulated, and the stimulation results are analyzed.