用fdatool设计一个50Hz陷波器，导出系数，编程，对原始信号signal.txt进行滤波。本程序为C程序。-50Hz with fdatool design a notch filter, export coefficient, programming, filtering the original signal signal.txt. This program is C program.

通带截止频率 =2 4k rad/s，阻带截止频率 =2 8k rad/s，通带波纹系数 =0.3dB, 阻带波纹系数 =50dB,采样频率fs=20000Hz。-The digital filter are the digital signal processing important content, the digital filter may divide into IIR and the FIR two main kinds. As for the IIR digital filter