基于数字滤波平方率的符号定时恢复算法。输入参数：RtfSig过采样的待恢复信号，信号中的N符号总数，dS升采样率，N_T升余弦滚降滤波器系数-A timing recovery algorithm based on the sign of the digital filtering of the square. Input parameters: RtfSig be over-sampled signal recovery, the total number of N-symbol signal, the sampling rate dS l, N_T raised cosine filter coefficients