| Synchronization is the key of frequency-hopping (FH) communication, which can receive FH signals correctly only after the realization of fast and accurate synchronization. The performance of synchronization impacts the capability of FH system. Meanwhile, synchronization is the difficult technology of the development FH system, especially to be designed exactly in the high-speed FH system.Firstly, it is analyzed the requirement of frequency-hopping communication on digital transmission in this paper, and particularly introduced an algorithm for GMSK modulation based on DDS and DSP, as well as a two-bit differential detection of GMSK using decision feedback algorithm based on DSP. Based on these, it is proposed a GMSK demodulation scheme based on DDC (Digital Down Converter) with low computational load. This method greatly reduces the computational complexity when it operates at the best sampling moment. The simulation results demonstrate that the scheme has good performance in the condition of guaranteeing DDC crystal stability. Secondly, it is proposed in the paper a synchronization scheme with TOD plus Sync-Head according to the practical development requirement, and analyzed the performance of synchronization. Subsequently, it is used Matlab/Simulink to set a simulation model of frequency-hopping communication system to simulate the GMSK modulation, demodulation algorithm and improved synchronization scheme. At last, it is given the processing flow of receiver terminal and testing results on the TMS320C6X Software Radio Platform. |
