全数字接收机中高阶QAM信号的符号同步

将Gardner时间误差检测算法和分段抛物线拉格朗日多项式插值算法应用于高阶QAM信号全数字解调时的符号同步,分析了环路带宽、插值点位置、取样率对接收机性能的影响.数值仿真结果表明,对于采用256QAM调制的标准DVB-C信号,当环路带宽小于9E-2fs时插值误差是影响接收机性能的主要因素,对于给定的插值多项式,要降低插值误差,只能提高取样率.当取样速率为8样点/符号时,接收机的误符号率性能已接近理论值

Symbol Synchronization in High Order QAM Digital Receiver

Gardner Algoithm for symbol timing error detection and polynomial based Lagrange piece-wise parabolic interpolator were used as symbol synchronization method in digital receiver for high order QAM signals. Extensive simulation were conducted to evaluate such factors as loop width, fraction time interval and sample rate which affect the performance of receiver. Numeric results shown for standard DVB-C signal with 256QAM constellation, when the loop width not exceed 9e-2 fs, interpolation error is the key contributor for the SER performance of the receiver. Given interpolation polynomial, the only method to reduce the interpolating error is increase the sampling rate. When the sampling rate is 8 samples/symbol, the receivers SER performance very close to the theoretical bounds.