摘要： 为提高高阶正交幅度调制(QAM)解调中载波恢复的收敛速度及跟踪稳定性,基于软件无线电设计思路和传统科斯塔斯(Costas)环基本原理,提出一种改进型Costas环的研究方法。该方法采用符号鉴相器代替传统的乘法器鉴相器,设计的环路滤波器运用多系数调整取代传统的一组系数调整。以1024QAM信号解调为例,通过使用Matlab/Simulink下的System Generator工具箱对解调系统建模仿真,以验证其载波恢复性能。仿真结果表明,改进的Costas环能准确地对接收的高阶QAM信号进行载波恢复,且与传统算法相比,改进后的环路跟踪平稳、收敛速度更快速、误码率更低,较好地改善了通信质量。
关键词:
载波同步,
科斯塔斯环,
高阶正交幅度调制,
System Generator仿真,
环路滤波器
Abstract: In order to improve convergence speed and tracking stability for high-order Quadrature Amplitude Modulation(QAM) demodulation carrier recovery,a new kind of Costas loop is designed based on software radio thought and the basic principle of traditional Costas loop. It is designed with sign phase detector instead of the traditional multiplier,and multi-factor adjustment replaces a set of coefficients in loop filter. Carrier recovery performance is verified by modeling and simulation using System Generator toolbox under Matlab/Simulink software for 1024QAM demodulation.Simulation result shows that the improved Costas loop can recover the carrier from received signal accurately for high-order QAM,with stable tracking,faster convergence,and lower bit error rate compared with traditional one,which improves the communication quality.
Key words:
carrier synchronization,
Costas loop,
high-order Quadrature Amplitude Modulation(QAM),
System Generator simulation,
loop filter
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