Research And Implementation Of Trellis Coded Modulation Technology For Ultrashort Wave Transceiver

With the continuous development of communication technology, frequency band resources become increasingly scarce, how to carry out high-quality communications while saving power and bandwidth resources has become a hot research. Based on the Link-11 tactical data link terminal technology, this thesis studies the TCM-8PSK and TCM-CPM trellis coded modulation schemes based on the RS concatenated code under the ultrashort wave in the actual project.Compared with the uncoded QPSK, TCM-8PSK has 3-6dB power gain without any change of the transmission rate and bandwidth conditions. Continuous phase modulation (CPM) has a constant envelope and continuous phase characteristics,with high power and bandwidth utilization. The TCM-CPM system, which combines trellis coding and CPM, has both advantages. In this thesis, TCM based on different concatenated codes schemes are compared, and the result implied that CPM modulation has better band utilization and BER performance compared with MPSK modulation.In this thesis, the technology involved in the whole system is briefly analyzed, including the error control coding technology, the receiver synchronization technology, and the principles of TCM technology are expounded. At the same time, the principle of TCM-8PSK modulation and demodulation, the method to applying optimal subset partition are expounded,and the influence of convolutional code number of states on the performance of coding gain is studied, and the basis of using parameter is presented.Then the phase trajectory and power spectral density characteristics of CPM signal are studied in detail, and the CPE + MM decomposition mode of CPM signal is given. Based on this model, the modulation and demodulation of CPM signal is studied and optimized. According to the actual design requirement, the parameters are simulated by MATLAB, the influence of parameters on CPM signal is studied, and the parameters used in TCM-CPM system are determined.At last, we compare the two schemes based on RS forward error correction code and choose TCM-CPM scheme with better band utilization. Considering the complexity of hardware, the complexity of realization and the requirement of real-time, the complexity of demodulation algorithm in TCM-CPM system is realized. In terms of DSP TMS320C6657 dual-core system platform, some performance is sacrificed to realize the feasibility, the test shows that the indicators of the system to meet the specified requirements.