▍1. Fractional_Delay_FIR
功能描述： 小数延迟FIR滤波器，对参考阵元信号signal_ref进行 length(tau) M次延迟，分别得到M个阵元的采样信号 关键问题： 若τ 1.2Ts,则Delay(i) 2,tau_valid(i) 0.2Ts 若τ 0.6Ts,则Delay(i) 1，tau_valid(i) -0.4Ts 当tau_valid(i)>0或<0时，从卷积后的数据y_FIR_delay中取值启示位置不同 函数能够实现输入任意延时tau，输出信号波形与理想波形之间误差很小。( Description: fractional delay FIR filter array element of a reference signal signal_ref performed length (tau) M delay times, respectively, to obtain a sample signal array element M key question: if τ 1.2Ts, then Delay (i ) 2, tau_valid (i) 0.2Ts if τ 0.6Ts, then Delay (i) 1, tau_valid (i) - 0.4Ts when tau_valid (i)> 0 or < 0, the volume data y_FIR_delay product after the Enlightenment values at different positions function can be realized enter any delay error between tau, the output signal waveform and the ideal waveform is small.)
