提出了一种采用非线性变换的MPSK/MQAM类信号符号速率盲估计方法,充分利用了MPSK/MQAM数字信号相邻符号的相位变化信息,通过对零中频信号进行非线性处理,构造一个非线性变换的复数函数,生成含有符号速率的离散谱线。利用四阶累积量的方法实现在强背景噪声下提取符号速率的基频分量。该方法运算简单,适应性好,对MQAM和MPSK调制的不同阶数、不同成形滤波器系数的信号均适用,低信噪比下仍具有很好的测量性能。
A blind method for symbol rate estimation of MPSK/MQAM signals by using the nonlinear process is presented.Utilizing the phase changing between inter-symbols and through the nonlinear transforming of zero IF signals,the spectral lines corresponding to the symbol rate can be extracted.The fourth-order cumulant is used for suppressing the strong background noise of symbol rate spectral lines in this paper.This method is robust to Gaussian noise and can achieve good estimation results with lower SNR.At the same time,it has lower computational complexity and is applicable to different shaping filters and different modulation orders of MPSK/MQAM signals.