短波16QAM信号数字解调算法的仿真

该文利用MATLAB平台仿真了短波16QAM信号数字解调中的三个关键模块——定时同步、载波恢复及自适应均衡。短波QAM信号经定时同步提取定时信息，为传输中的码元提供了判决基准并为均衡器提供了时间基准，通过载波恢复可调整信号中存在的频偏和相偏，最后经自适应均衡达到抑制甚至消除码间干扰的目的，恢复出QAM的星座图。该文根据16QAM信号星座图的特点，提出了一种基于COSTAS环简化的载波恢复算法，将该算法与常用的载波恢复算法进行仿真比较，实验结果验证了该算法的有效性及优越性。通过对解调中三个关键模块的仿真，为实现整个解调系统奠定了基础。

Simulation of HF 16QAM Signal's Digital Demodulation

In HF channel, the key modules of QAM signal's digital demodulation, symbol synchronization, carrier recovery and adaptive equalization are simulated by MATLAB in this paper. Symbol synchronization can provide the judicative benchmark for transmitting codes and the timing benchmark for equalizer. Carrier recovery can adjust the frequency and phase offset. Adaptive equalization can restrain or even remove the intersymbol interference,and finally resume the constellation of QAM signal. According to the structure of 16QAM constellation ,a new algorithm for carrier recovery is presented and compared with the common algorithms. The results of the simulation validate the advantages of the new algorithm. The simulation of the three key modules establishes the foundation for realizing the whole demodulation system.