一种QAM同步方案的研究与实现

正交幅度调制（QAM）是一种频谱利用率高、实现较为方便的载波传输方式。针对高阶QAM系统对于载波恢复、符号定时的严格要求,提出并实现了一种全数字同步方案。在发送端插入导频,接收端先利用LMS自适应陷波算法分离导频和信号,接着使用NVS算法自适应地完成载波跟踪,然后将解调后的信号送往符号定时模块,通过基于能量检测原则的最大平均功率内插定时算法实现码元同步。基TI的TMS320C542芯片的实现,表明上述方案是完全可行的。利用QAM技术对传统的电力线载波机进行改造,可大大提高其容量和性能。

Investigation and implementation of an QAM synchronization scheme

Quadrature amplitude modulation(QAM)is a way of carrier transmission that has high spectrum efficiency and is easily implemented. To satisfy the stringent requirements of carrier phase recovery and symbol timing for a QAM system with a large constellaiton, this paper presents and implements an all digital synchromization scheme. The transmitter inserts a guiding carrier; the receiver separates the QAM signal and the guiding carrier with LMS adaptive algorithm, then using NVS algorithm to track the carrier adaptively. The demodulated data is sent to the symbol timing block to carry out symbol synchronization with a maximum mean power estimate interpolating algorithm. The implementation of the scheme on TMS230C542 indicates that the scheme is feasible. Using QAM techniques to rebuild the traditional power line carrier transmission system will greatly enhance its capacity and performance.