A Research Of QPSK Carrier Synchronization And Modulation Implementation In DSP

It is difficult to get synchronous carrier in digital communication, especially inhigh dynamic environment, great Doppler frequency shift causes the existing carriersynchronization technique hard to apply. Currently, QPSK is widely used in satellitecommunication which is high dynamic environment. This paper studied QPSK carriersynchronization in the high dynamic environment and realized QPSK communicationsystem on DSP.Based on systematic study of the existing carrier synchronization scheme, Isimulated digital phase-locked loop. A QPSK communication system was built withMatlab, simulation for QPSK communication performance under the circumstance oflarge Doppler frequency shift was also finished. The author studied the carriersynchronization scheme of high dynamic environment, gives a frequency wavesynchronization scheme that was a FLL combined with a PLL, which can be used inhigh dynamic environment. The original algorithm was also improved, throughsimulation and analysis, the capacity to resist Doppler frequency shift can reach to100KHz level.In addition, the author carried out some research on the QPSK digital modulationimplementation, a QPSK digital modulation algorithm was finished in theTMS320VC5509A digital signal processor. Various related peripherals includingmemory and other resources used in hardware system were carefully configured. Finallya complete QPSK digital modulator was achieved.